[" The
Cyanide
Process
of
Gold
[Published
by
CimiLKa
Griffin
"
Co.,
Ltd.,
London
.]
THE
CYANIDE
PROCESS OF
GOLD A
EXTRACTION:
TEXTBOOK
FOR
USE
THE
CYANIDE
AND
METALLURGISTS,
MINING
OF
STUDENTS, OPERATORS.
BY
JAMES PROFESSOR
OP OF
FELLOW
MINING THE
AND
DIRECTOR
GEOLOGICAL
INSTITUTE
OP
MINING
MKTALLURGY,
[The
First
ENGLISH
English
published
itl) JTronttgpieee,
(Authorized
Text-book.
GRIFFIN EXETER
MINES;
OF
SUPERINTENDENT, WORKS,
AND
REVI8ED
in
and
New
ENLARGED.
enlarged from
the
Third
Australian
anb
Schools
Illtxgt ration*.
of Mines.)
:
"
STREET,
Edition
Zealand.]
opiate*
LONDON CHARLES
OF AMERICAN
GOLDFIKLD.
revised
was
THE
INSTITUTE
THE
METALLURGICAL
EDITION.
Edition
OF
; LATE
GOVERNMENT
SCHOOL OF
MEMBER
;
MEMBER
LONDON
THAMES
THIRD
LONDON
OF
ENGINEERS;
ZEALAND
UNIVERSITY
OTAGO
OP
SOCIETY
MINING
AND NEW
PARK,
COMPANY, STRAND.
1904.
[All Rights Reserved.]
LIMITED,
Complete
A
Catalogue
of
Works
Engineering, on
post
Metallurgy
and
Mining,
free
application on
be
will
to
the
forwarded
publishers.
'
"o**'bOA
78161 APR
14
1904
MKWL •Pa.
i
PREFACE
TO
favourable
The
much
revise
old
the
gold-slimes,the
of
In
filter-press practice. pressing
of the
character
density
for
formed
the
value.
In
slimes
the
are
The
treatment.
Africa,
South
has
in all
for
gold
milling the
where
been a
cases
so
the
saline The
purposes.
the
of
slow, laborious, and
of
attention
secondary product
imperative
should
mills, and
question
engaging
and
ores
settlement
slimes,it
of the
filter-
the
water, and
almost filter-presses
of
primary product
or
decantation
versus
fresh
of the
and
peculiar
of
the
use
lead-
to
adoption of
process
effective
first
the
combination
a
rendered
waters
add
sulpho-tellurideores,
tendency
available
couraged en-
time
same
decantation
make
to
and
quick
the
in
imperfect as
by
has
part, relates
Australia,
natural
water
brackish
material
finer
only
the
of
of
editions
the
at
most
slimes, the scarcityof
form
to
and
the
Western
earlier
to
treatment
local conditions, namely, the matrix
for
determined
mainly
was
EDITION.
matter,
material, which,
new
smelting
accorded
reception
to
me
THIRD
be
noted,
of
were
high
filter-pressing
for and
time,
some
of
low-grade
value. been
Filter-pressinghas Waihi
Company,
slimes, but,
on
in New
the
other
neighbouring companies for
the
treatment
relative
merits
by
Zealand, hand, are
of similar of the
exhaustive
two
trials
for
the
it should
be
satisfied
with
material.
processes
over
of
mentioned
that
is in a
by
success
treatment
the
It
must,
extending
much
with
adopted
ordinary
decantation
several process
quite
clear
that
every
case,
be
period of,
the
say,
the
mined deterfour
to
^PREFACE.
VI
mouths,
six
so
of
favour
in
costs
be
to
that The
introduction
notable
the
in
the
in
short
a
New
obviously
of
Zealand of
one
cost.
subordinate
is
cost
several
to
The
process.
this
and
is
American
chemists.
awaited
with
interest.
have
much
to
acknowledge and
M.I.M.M., contributions
Waihi
on
the
B.
Allen, and
slime
goorlie sulpho-telluride practice the
of Australian articles
In
these
and
are
made
in
Mining
Journal,
Mining
Standard
which all the
other
appeared cases,
their
and the
to
columns
at
acknowledgment
make
1903.
N.Z.,
prietors pro-
extracts
different and
Kal-
Journal,
times.
reference
text.
Dunedin,
September
special
for
to
be
Banks,
Engineering
permission
is
will
G.
E.
and
JAMES
University,
solutions
B.Sc,
M.A.,
cyanide
work
Mr
respectively;
for
due
the
have
investigation by
their
to
in
number
Africa of
of
of
and
plants.
a
filter-press practice
Mining
in
of
cyanide
subject
indebtedness
treatment
investigation
literature
results
prehensive com-
cyanide
South
foul
Mr.
of
more
acid-
researches
of
a
lead-smelting
—
and
in
the
to
my
by
chemical
chemists
The
Frank
Mr
verified
the
respect
claims
probable
special
present
several
the
smelting
regeneration at
if
larger permanent
material
successful
still unsolved,
the
metallurgical
valuable
much
old
the
for
in
and
most
seems
marks
gold-slimes
are
process,
room
and
directions,
accomplished
the
all
in
rate
any
of
practice,
displace
is still much
There
from
of
question
indeed
as
time
at
processes,
and
is
chance
estimate
and
African
lead-smelting
of
—
I
reliable
a
problem
cyanide
author
trials
added
the
of
of
advance
Tavenor,
of
South
fortuitous
of
enable
thereby
solution
Australia,
element
expediency.
of
will
the
With
prepared.
Western
In
and
either,
the
conditions,
eliminate
to
as
PARK.
TO
PREFACE.
ENGLISH
FIRST
THE
EDITION.
The
favourable
work,
and
available
this
on
the
of
retained
in
England,
and
as
of
the
the
and
and
perplexing
most
Gold
of
this
due,
problems,
in
of
than
often
in
presents
the
to
ores
chemical
obvious
cases,
in
application
on
which
many
been
treatment
more
Extraction,
has
the
the
of
use
introduced
dependent
more
is
department
the
been
years
to
general
published
first
have
late
methods
and
The
operators,
changes Of
more
no
Process
Cyanide
the
in
such
information
for
the
is
his
before
placing
intended
which
again
to
latest
cyanide
needful.
metallurgy
knowledge,
and
only
investigations
rendered
has
which
into
of
this
of
author
metallurgy.
was
edition,
present
considered
scientific
which
work,
the
the
of
metallurgists,
the
author
branch
Edition
Third
view
a
anticipated,
progressive
students,
mining
with
was
original
"
enabled
has
text,
than
earlier
readers,
plan
the
enlarge
the
to
Zealand,
New
in
published
revise
accorded
reception
simplest
causes.
In
the
been
the
greatly and
while
added,
slimes,
closer
although Since
treatment
edition
present
information
of
solutions,
;
setting, the
the
text
revision
have
while, the
has
the
by
been
of
largely
relating and
considerably these
cyanide of
adoption
number
actual
pages,
superseded
and
illustrations
new
the
analyses
extended
several
of
pages
the
to
tables
has
of
treatment
poisoning, slightly
have
has
smaller
been
been
type, reduced,
enlarged. wet-crushing dry-crushing
and
and
cyanide direct
PREFACE.
Vlll
cyaniding attended
been
with
chalcedonic
associated
varying
The
complex by
the
in
author
of
world-wide
a
mines.
The
both
The
varying
and
January
in
occurs
strengths
unremitting
of
care
large mostly
are
ores
fine
separate
the
of
treatment
interest,
and
these
have
solution
part
1900.
comparatively been
gold
constantly
the
on
embodied
appendix.
JAMES Auckland,
the
coarse
silver
has
charge. in
in
installation
notwithstanding
contain
and
obtained
are
the
sulphide.
extractions,
results
ores
and
requiring
proportions,
metallurgist
the
of
their
case
every
success,
some
silver
with
adequate
obtain
at
character,
in
in
complete
slimes
of
proportion
and
Zealand,
New
in
PARK.
to
of
OF
TABLE
CONTENTS.
I.
CHAPTER
PAGE
The
1
Process,
Forrest-
McArthur
CHAPTER
Chemistry
op
IT.
Process,
the
4
III.
CHAPTER
17
Experiments,
Laboratory
IV.
CHAPTER
Control,
Testing,
and
Analysis
of
Appliances
Extraction
Actual
48
by
Treatment
of
of
by
VII.
80
VIII.
98
Concentrates,
CHAPTER
Leaching
69
Slimes,
CHAPTER
Treatment
VI.
Cyanide,
CHAPTER
The
V.
Plant,
and
CHAPTER
The
22 ....
CHAPTER
The
Solutions,
Agitation,
IX.
96" •
•
b
ILLUSTRATIONS.
OP
LIST
X
CHAPTER
X. page
Zinc
Precipitation
Treatment
and
Application
of
121
XII. 171
Process
Sibmens-Halske
XIII.
CHAPTER Other
Cyanide
177
Processeb, XIV.
CHAPTER Antidotes
.
.
Process,
the
CHAPTER The
.100
XI.
CHAPTER The
Slimes,
Gold
op
184
Poisoning,
Cyanide
for
188
Index,
LIST
ILLUSTRATIONS.
OF
PLATES. PAGE
Cyanide
Mammoth
Leaching
I. Wooden II. II
Steel
IV.
Zinc
IVa.
Zinc
VII.
Extractor
Slime
IX.
.
Discharge
Door,
58 .
.
,,
62
Box,
.
.
New
Box,
and
.
Plan
.
.
.
.
.
.
,,
.
.
,,
74 ,,
,,96
Room,
Agitators
,,
74
Furnace, Elevation,
and
.
64
Pattern, Roasting
.
Plant
Roche's
52
to/ace
....
,,60
Distributor,
Precipitation
IX.
Bottom-
Distributor,
Tailings
VIII.
.
.
Door,
Extractor
Butters'
VI.
Supports,
54
Improved
Butters'
V.
and
Frontispiece
„
Side-Discharge
III.
Vat
Africa,
Vat,
Park's
a.
S.
Plant,
at
Waihi,
,,136
Waikino,
Bottom-Discharge
138 .
.
Door,.
.
,,
138 .
.
.
,,
WOODCUTS. Fig.
1.
Showing
Turn-Buckle
Fig.
2.
Butters'
Bottom-Discharge
Fig.
3.
Irvine's
Fig.
4.
Side-Discharge
53
Bottom-Discharge
Door,
57
Door,
58
Door, .59 .
.
.
.
.
THE
PROCESS
CYANIDE
FOR
EXTRACTION
THE
OF
GOLD
AND
CHAPTER
THE
It
has
been
of
alkaline
solutions years to
that
the
this
is
solvent
a
remarkable
the
and
;
mark
the
for
natural
the
in
epoch
an
the
The
cyanide of
or
of
free-milling
tailings
copper-plate It
refractory a
process
and
in
ores
which
also
ores,
finely-divided
be
used
especially form
or
for those
that
with
even
the
most
metallurgical
in
of for
in
occurs
the
all
fact time.
the
amalgamation
fine
the
ment treat-
particles, and
wet-crushing
from
treatment which
to
success
dry-crushing
in
potassium
among
extraction
gold
the
the
of
application
resulting
concentrates
amalgamation,
can
applied
be
can
ores.
century
gold
scale
PROCESS.
THE
OP
ranks
few
past
commercial
a
solution
successful of
the
their
dilute
present and
on
from
in
soluble
are
within
only
gold,
history
SCOPE
silver
applied
the
that
widespread
is
metals
preoious
of
it
been
fact
discoveries
science
but
has
the
and
gold
cyanides,
of of
PROCESS.
that
knowledge
discovery
cyanide
must
known
extraction
The
I.
M°AKTHUBrFOEREST
long
SILVER.
and of
gold
tion. pan-amalgamamany
so-called in
occurs
in
such
fails
pans
1
to
2
PROCESS.
CYANIDE
THE
in of ores of the values; or satisfactory percentage the gold is coated with of metallic which oxide or sulphide, a film and the gold is assoin it which ciated ores rendering non-amalgamable, matrix. a with, or entangled in, highly pyritic
recover
a
All
the
solutions
(AgCl)
common
and
the
abundant
most
is much
slower
the
rate
than
that
of
cyanide of
treatment
condition.
less soluble
or
ores
When
dissolution
of
gold,
and
is
of
in
chloride
the
are
dilute
fortunately
silver
and
accompanied by
its a
the
ores
higher
cyanide.
LIMITATIONS
The
more
most
; but
of
consumption
are
readilysoluble sub-sulphide(Ag2S), and these are Those
cyanide.
of
of silver
ores
OF
cannot process the in which an
ore
be
gold
contains
PROCESS.
THE
applied occurs a
with
even
success
in
proportion
a
to
the
fairlycoarse
of both
fine
and
fine be extract to cyanide process may will have be used to to supplementary treatment a gold, but the slowness of the the dissolution gold, since recover coarse take would too long for a commercial basis of working. With of the latter class the of the free-milling ores recovery coarse gold is generally effected by copper-plate amalgamation ; the of in case and, wet-crushing, this treatment precedes the of dry-crushing, it follows it. cyanide leaching, while, in the case has of the cyanide process The experience gained during the use when that of potassium cyanide, even shown solutions very dilute, all the and carbonate act most ores sulphide, oxide, energeticallyon of and also the and bismuth of on sulphides antimony ; copper, these of is in small hence, when present, even proportion, any becomes of the ore sometimes the treatment difficult,and sible, imposthe of account on great consumption of cyanide. In practice that an unduly large consumption of cyanide is generally it is found of the accompanied by a low rate of extraction gold and silver in the ore contained or tailings. the foregoing it is obvious that From the process will be most the which the in of ores in in a successful treatment gold occurs and in which the base fine of minerals state, or quantity very to cyanide, is small. metallic salts,destructive coarse
gold
Further,
the
the
the
used
author
ascertained
as
the
result
of
many
taneous simul-
Government working trials in the N.Z. Metallurgical which amenable that argentiferous gold ores Works to treatment were Washoe in the most cases pan-amalgamation by process, results when better tained cyanide by treatment, even they conyielded small percentage of zinc and lead. a
M°ARTHUR-FORREST
THE
An
intelligent
widen
the
point of
ores
of
the
scope is
the
America
progressive
of
and
of
the
original
trend
of
cyanide
has
the
affords
important
rich
to
to
many
greatly
notable
case
sulpho-telluride
satisfactory branch
experience
led been A
process. of
which
this
which
of
by
has
requirements
treatment
Kalgoorlie,
backed
principles
tendency
successful and
first
working the
adaptations,
ingenious
in
details
working
of
knowledge
3
PROCESS.
of
evidence
metallurgy.
CHAPTER
THE
When
gold
cyanide,
CHEMISTRY
acted
is
a
by
(AuKCy2),
PROCESS.
solution
aqueous when
which,
the
having
THE
an
obtained
is
crystals
cyanide
OF
on
solution
octahedral
II.
is
which
takes
double
a
potassium
evaporated, of
composition
which
of
the
yields
auro-potassic
cyanide
and
gold
of
potassium. The
reaction
exact
equation
:
required
the
rate
reaches
a
of that
the
dissolution
of
maximum
character determined A
weak
rate
On
of
most
now
the
by
ing follow-
a
a
is
*
Skey,
f Jour.
the
of
laboratory
always N.Z. Chem,
Soc.,
of
correct
shown
0*25
the
conditions,
it per
was
cent,
varies ore,
that
concentrated
maximum
and
can
tions solu-
proved solution with
easily
the be
experiments. active
more
Mines
to
a
of
constituents
port sup-
those
have
experiment, with
scale
working
series
solution
reached
was
from
theoretical
dilute
actual
for
subject
Maclaurin
under
from
the
substantial
experimentally
the
on
and
is
oxygen
employed
and
1891,
proved
gold,
By
of
received
in
Skey
passing
mineral
the
by
gold.
one
ounce
cyanide
paper
pure
cyanide.
maximum
cyanide.
of
maintain
4KHO.
+
an
has
been
of of
in
potassium
view
classical
his
AuKCy2
potassium
since
researches
valuable
The the
4
=
experiments has
t in
Maclaurin
by
the
is
represented
equation,
This
gold.
and
1892,
2H20
+
of
author's
the
in
the
on
1842
is
others
acts
subject
a
authorities,
some
while
;
in It
above
pound
every of
02
+
the
to
from
Skey*
8KCy
+
According
dissolution
Eisner
chemists.
by
to
then
still
by
—
4Au
for
and
dissolved
is
being
According dissolved
is
by
gold
understood,
oxidized
suggested
accepted
generally
it
first
is
reaction
The
well
yet
before
cyanide
the
that
not
uncertainty.
oxidized
is
gold
the
and
doubt
much
of
is
cyanide
potassium
when
place
Report, May
than
a
1894.
1893,
p.
724.
strong
one,
and
THE
that
considers
Maclaurin
OF
CHEMISTRY
fact
remarkable
this
5
PROCESS.
THE
accounted
be
may
the of dissolution of gold is partly rate by supposing of cyanide molecules in a unit volume dependent on the number ; the the molecules in number of and same partly on oxygen volume. One of the most important results of his exhaustive the of the fact that the demonstration experiments was solubility with in solutions of the of oxygen decreases concentration cyanide that
for
solution. Weak action
gold
on
of
ores
solutions
aqueous and
silver
and
copper
cyanide
when
This
a
marked
very associated
are
with
becomes
circumstance
of
treatment
exert
metals
these
antimony. the
during
prominent
of
cupriferous
ores
on
very
large
a
scale. The those
cyanides of of the
alkaline
heavy metals,
insoluble.
are
the
The
metals
with
insoluble
the
soluble
are
exception
salts
are,
of
in
gold
and
mercury,
soluble
however,
while
water, in
excess
of
potassium cyanide. of an use oxidizing agent that will in a cyanide solution portion of its oxygen The
feature
several
of of such
gold
agent
an
contained
solutions
in
artificial
supply atmospheric
to
of
aeration
oxygen
with
a
essential
ment employof
the
cyanide with
the
object.
same
of
Consumption about in
The
ore.
is undertaken
the
The processes. accelerate the dissolution
to
serves
the
forms
cyanide
patent
new
readily part
lbs. of
4*5
Cyanide.
cyanide
dissolve
to
100
Eisner's of
ounces
equation, gold, but
that nearly forty times The which causes quantity. operate in the practice of the process of cyanide, over to effect so large a consumption that required by Eisner's simple equation, are at present not fully investigated. To dissolve 100 of silver would oz. require 7*5 lbs. of cyanide, the to : according equation it
practice
found
According
—
should
is
that
takes
it
—
4Ag For
the
+
8KCy
+
dissolution
02 of
7*01
sulphide (Ag2S), following equation':
lbs.
2H20
+
100
oz.
of
4(AgKCy2)
=
of
cyanide
silver would
+
4KHO.
existing as the be required by
subthe
—
Ag2S The
+
4KCy
=
2(AgKCy2)
+
K2S.
of silver potassium sulphide resulting from the dissolution further loss of cyanide by precipisulphide also tends to cause a tating which will of gold free to excess require an cyanide redissolve it. It is the need this for of excess cyanide which necessitates the of solutions in the use ^comparatively strong of argentiferous gold ores. treatment
6
THE
CYANIDE
PROCESS.
Potassium
cyanide is, chemically, a most possessing the property of forming complicated and unexpected combinations acids
mineral
and
different
with
be
only
base
classes
of
unravelled
that
metals,
large
so
in
pound, com-
number
a
of
the
of presence and behaviour
reactions
under
and
ore,
its
organic
active
varying conditions,
much
can
tory labora-
by patient research, conditions. working of ores During the treatment by the cyanide process, the most with, requiring the constant puzzling difficulties are continually met and attention of the metallurgist in charge. care of the Causes of LOSS Some of Cyanide. principal and loss obvious the of of takes more enormous causes cyanide which place in the working of the process are as follows : 1. Loss tanks. vats or by absorption in wooden 2. Loss by decomposition by atmospheric carbon dioxide. 3. Mechanical loss in residues, and dilution of solutions by during washing. 4. Loss by decomposition due of mineral acids to the presence both
the
in
under
and
—
—
~
-
-
and
salts.
5.
Loss
due
6.
Loss
when
7. Loss
exists
ores
soluble
of charcoal in kiln-dried ore. presence is in This Vats. Absorption especially noticeable
by
—
the
At
Witwatersrand
Goldfields,
is said
cause
of
amount
the
"
below
cent,
per
rises
With
Loss Dioxide.
the
theoretical, but
within
to
determined
by iron
or
due
assay. steel vats
to
the
liberation
prussic
acid
there
six
is
per
of
acid
the
first
a
few
cent,
of
from
of pound " clean monthly to
is often
loss
a
twenty months the
more
or
it
ally gener-
extraction
as
appreciable loss by absorption.
no
by Atmospheric
of gas formation
Carbon
the
atmosphere decomposes potassium carbonate, hydrocyanic (prussic)acid, thus :
with
2KCy The
to
after
Decomposition carbonic
The
—
three
potassium cyanide and
cyanide.
amalgam.
as
to by Mr. C. Butters treated. At tailings cyanide per ton in a new plant, the actual extraction up
this
in
the
to
plants.
new
of
presence
gold
due
Loss in
to
thus
the
of
—
+
C02
+
H20
liberated
=
K2C03
would
be
+
2HCy. neutralized
by
any
cyanide solution. in Residues, and Mechanical Loss during by Dilution the there is to extract an During washing inability 'Washing. the of residual dilution whole of the cyanide from tailings. The also occasions loss of cyanide in washing. the cyanide solutions a is formed, A large quantity of dilute a cyanide solution portion utilized make be to can only of which up fresh solutions. caustic
alkali
—
present
in the
8
THE
CYANIDE
PROCESS.
sulphate, insoluble other
basic
react
upon
basic sulphates, and probably also traces of complex and variable composition, all of which of potassium cyanide, thereby causing a loss solutions
salts of
cyanide.
of
which reactions most are likelyto take place in acid of cyanide are tailingsin the presence : of hydrocyanic acid. (a.) The liberation of ferro- and (b.) The formation ferri-cyanides. The free acids in the ore shown the cyanide as react on by equation :
The
or
ores
—
the
—
2KCy Feldtmann
liberated
diffuse
itself
K2S04.
+
the
it
considers to
2HCy
H2S04=
+
possible for through the
ore
hydrocyanic and
dissolve
acid
thus
appreciable
he the strongly condemns quantities of gold.* For this reason the these of in acid must washing tailings leaching vats, as practice which residual always contain a portion of cyanide from prussic acid would be liberated. Any gold dissolved by this gas would
carried
be
in
away
the
water
alkaline
or
which
of
he
loss, possible source mysterious discrepancy sometimes the
actual
found
recommends
he
; and
wash
thinks
avoid
to
for
account
may
between
the
the
assay
this the
and
of
washing in one system and On in another. the other cussing disvat hand, leaching Skey, when this subject with the author, stated that hydrocyanic acid solvent It is obvious, however, for gold. that this not a was liberated of any alkali residual in the HCy in the presence vat, alkaline form would an cyanide capable of dissolving and removing and this combination Feldtmann in his mind gold, probably had of writing. time at the Of the iron salts, the one of most in pyritic common occurrence the is ferrous soluble ores or tailings sulphate (FeS04), which with form reacts potassium cyanide to potassium ferro-cyanide and sulphate, thus : extraction,
.
.
—
FeS04
6KCy
+
K4FeCy6
=
+
K2S04.
is, in potassium ferro-cyanide thus formed still ferrous of sulphate excess by any present blue of Prussian according to the equation :
its turn,
The on
I
with
the
reacted
tion produc-
—
3K4FeCy6
+
6FeS04
+
30
Fe203
=
+
6K2S04
+
surface
of
Fe4(FeCy6)3. i
A
blue
in the
seams
colour
in the
of the *
solution,
staves
Feldtmann,
of the Notes
on
on
the
vats, indicates Gold
a
Extraction, p.
the
tailings,or large consump5.
CHEMISTRY
THE
9
PROCESS.
THE
OF
V
tion
and
loss of
tion cyanide due to imperfect washing and neutralizaof the acidity in the preliminary treatment. A white the surface of seen soum or on precipitateis sometimes the This solutions when precipitate they are coming off acid. into Prussian turns blue by exposure to the air and light. ferric in The normal water, sulphate Fe2(S04), is insoluble It and be removed oannot reacts by ordinary water-washing. with loss due the to of potassium cyanide, causing a cyanogen of prussic acid and liberation the formation ferric hydrate, of the shown as by the two following equations : —
Fe2(S04)8+ 6KCy
Fe2Cy6
«
3K2S04
+
and
Fe2Cy6
6H20
+
Fe2(HO)6
=
6HCy.
+
It is
and probable that in most partially oxidized pyritic ores tailings the ferrous and ferrio sulphates exist together, the former in large excess. the In this case decomposition of the cyanide result in the production of ferrous would cyanide and potassium thus sulphate, : —
12KCy In
the
the
3FeS04
+
Fe2(S04)3 Fe8(FeCy6)2 + 6K2S04.
+
=
the
of
earthy pyritic ores, result sulphides would
case
metallic
weathering or the production
in
of
the
hydrated
which
as
The careful to
All
reactions
preliminary
avoid
undue
the
iron
metals
insoluble
an
above
the
of
loss
alkaline
cyanide, and ensure earthy sulphates can application of an alkali before of
basic
ones
important and the
not
with
cyanide
solution.
cyanide Loss The
to
the as
due
be
to
the
Presence
sulphide, oxide, of antimony
and
and
salts
these
precipitated hydrate ; while
ferric
of
Ores
carbonate
bismuth,
ores are
iron
is
applied before, will
destroy
nearly neutral only, alkali and
acid
in
copper,
acted
It
a
Soluble of
alkali.
salts
in
as
the
are
of the presence alkali should be
a
cipitated pre-
ous innocuwith
treatment
to
strongly alkaline the free tailings contain applied together. in
rendered
be
the
cyanide solutions, as
much
When should
that
remember
in
iron
oxidizes
rapidly
oxidize
soon
soluble
be
solution
salts and
all the
the
of
would
pipes. necessity of a most pyritic material, in order satisfactoryresults.
of
treatment
formation
the
clearly emphasize
by the oyanide. By this means ferrous as hydrate, which the
in the
incrustation
these
on
question,
in
of
sulphates sulphates is cyanide with the
action The magnesia, lime, or alumina. not clear, but they most likely react very liberation of prussic acid, accompanied by
oxide
of
of
oxidation
on
Cyanide.— and
the
phides sul-
by potassium
10
CYANIDE
THE
PROCESS.
and cyanide both in weak a strong solutions, and thereby cause In in the ore. loss of cyanide in proportion to their abundance the treatment of an ore containing as little as 0*25 per cent, of the consumption of cyanide will be doubled. copper It is during the treatment the selective of cupriferous ores that An action of weak most ore cyanide solutions becomes apparent. solution contain 1 sufficient to cent, a decompose may copper per 0*35 of cyanide and give a low extraction of gold, whereas a per solution dissolve would cent, proportionately less copper, and give But the results of the gold. same a fairlysatisfactoryextraction would
obtained
be
shown
been
in
that
the
passing
from
solution, a
weaker
the
maximum
of that
metal
notice
The
ore
free
from
bright
chemist in
an
on
the
on
and
even
An
the
at
by
Crown
source,
from
or
and
any Mr.
plant, of in charge, was small infinitesimally zinc turnings after
at
which
proved
gold.
pure
of zinc»precipitation in
in which
ores
the
of
this
mines
at
of almost
could not copper of the mechanical
be
trace
no
under
came
Karangahake. white
pure a
the
chemical
rigid
most
impurities ; nevertheless, coated often was precipitation boxes The
cent,
per
been
has
metallic
copper.
1
a
0*35
a
strength
which
instance
consisted
there
and
of copper
detected,
author,
cyanide
or
per of ores,
large samples.
metallic
outside
cent,
than
the
nearer
occurs,
existence
be
treated
all the
0*25
a
the
the
being
in
zinc
of
being
treatment
on
the
be
to
gold
more
mum maxi-
a
Hence
solutions.
strong
extract
solution
could
examination
to
of dissolution
rate
experimentally The cyanide gold, have shown
dilute
should
solution
cent,
per
of copper, for it has dissolution of gold reaches
of
rate
already
absence
in the
even
quartz,
portion with
of film
a
derived
from the
fittingsin
the of an
mill
Napier, the metallurgist and in the the ore opinion that it existed manifest and became only quantity, James
the
treatment
of
hundreds
of
tons
of
ore.
peratures, sulphate at low temCopper pyrites is oxidized to the soluble and this salt requires a greater heat to decompose it that It than iron is, therefore, probable a portion, at pyrites. in kilns, preleast, of this mineral present in an ore, being dried paratory be direct would to dry-crushing and cyanide treatment, an appreciable loss of cyanide in sulphatized, and thereby cause that caused similar to manner by the decomposition products of a
iron
pyrites.
Malachite
and
azurite, the
and
blue
in solutions readily soluble production of copper-potassic cyanide and
are
both
green dilute
carbonates of
of copper, cyanide, with the
liberation
of
prussic
also
readily
acid.
Antimonite,
the
grey
sesqui-sulphide of antimony,' is
THE
acted in
on
the
The
of
presence
to
have
small
a
of
THE
all the
to
at
It
attempts
is
Beef
Creek, them
large consumption
of
goldnelds. the large
ton
antimonite
treat
with
frequently met
and
Boatman's to
11
PROCESS.
of
percentage
tailings
caused
chiefly owing rate
OF
by weak cyanide solutions. of the Thames gold-bearing oars
accumulation said
CHEMISTRY
in
is
Reefton,
near
end
to
cyanide
failure,
in
and
the
low
of extraction.
Loss is well
of
Cyanide
known
most
Gold
when millmen
that
Exists
—It
Amalgam.
as
the portion gold in tailings,resulting from copper-plate amalgamation or panform When such of amalgamation, exists in the amalgam. treated be the the to dissolve to tailings have cyanide has well the thus as gold, as causing a larger consumption mercury of the solvent be would than if the gold existed in a necessary free
to
a
of
considerable
state.
According
Gmelin, cyanide; but
potassium process
has
to
shown
is
mercury the
that
his
not
dissolved
is
the
of
practical working conclusion
acted
or
contrary
by cyanide on
actual
to
experience. At the cyanide works Gold of the Cassel Extracting Company, at Waihi, where from residues stack of and a large tailings panof in 75 collected lbs. amalgamation were were treated, mercury the condenser attached for roasting the zinc slimes. to the furnace The thus recovered was only a small prpportion of the mercury dissolved precipitated in by the cyanide, and afterwards mercury the
zinc-extractor
roasting of
the
volatilized
was
with
zinc that
On
bullion.
slimes
pervaded
vapours
on
every silver worn
cool
surface, the
when
occasion
every
being conducted,
was
the
buildings, condensing all objects of gold and
so
every and
much
part
the
mercury of the
amalgamating
workman.
by during the roasting of zinc slimes, the of tailings, was noted treatment resulting from by the author several the Government occasions at on Experimental at the cyanide plants Cyanide Works, and is of frequent occurrence The Kuaotunu. at circumstance noted same was by Dr. Scheidel at the Sylvia Cyanide Works at the Thames, where was mercury found in the zinc-bullion in considerable quantities. The in the of generally occurs tailings in the form mercury amalgam in a very fine state of subdivision, and is dissolved by the cyanide, together with It is the associated gold and silver. with the bullion in the zinc precipitated precipitation boxes. Whenthe zinc oxidized the slimes are greater portion of the The
•
the
volatilization
mercury
Loss the
Ore.
of mercury
is volatilized.
of —
Cyanide It
has
due
long
to
been
the known
Presence to
chemists
of
Charcoal that
in
charcoal
14
CYANIDE
THE
PROCESS.
with these tion sulphides, in addinecessarily occur ; but will there be of to loss of cyanide, loss gold, and a still a in the of loss to silver, proportion quantities present. greater that This loss is brought about the is, the alkaline sulphur by sulphide sulphurizing these metals to form sulphides with them,* the sulphide film so formed the metal preventing, or greatly upon
cyanide
will
—
—
action of the proper does combine, and very
retarding,the That
gold the
both
already
alkaline shown,
It is to
cyanide
sulphide
and
of
cyanide solution. readily,with the sulphur of hydrogen sulphide, Skey has
t
precipitate the sulphur that
process
Mr.
that has
McArthur
into
gets
the
proposed
salt dissolved
cyanide
in the
or
does
to
use,
(as per patent),a soluble lead cyanide. for the at the is chemist works find a to cyanide problem and practicalmethod, whereby all the sulphur of antimonial rous cupwith be made the cyanogen, rather to combine sulphides can than the potassium of the cyanide. with The how following results obtained by Skey show extremely when alkaline the in objectionable sulphides are, present cyanide
use
in the
The
.
solution. solution
the
cyanide, containing a small placed over a strip of gold coupled with proportion of sulphur, was a piece of copper-glance (sulphide of copper), but no solution of gold was perceived ; however, on substituting chalcopyrites for the rapidly removed. copper-glance, the gold was that the This gold was sulphurized at the experiment shows outset sulphide present in the cyanide, and that by the alkaline it required connecting with substance of a strongly negative a A
rather
kind
order
in so
Further
1 per
strong
to
effect
the
of
decomposition
of
the
auriferous
phide sul-
formed.
experiments
of
a
solution
kind
different dissolved
showed
that
while
pure
given weight of gold in of the salt of the same ten taining strength, but conminutes, a solution of sulphur (as a ^sulphide),% required two ^ 0 0 part T0 the same to dissolve hours weight of gold. The speeds were as of the 1 in favour 12 to cyanide. pure what extent phurizing to The even a gentle sulfollowing results show its solution with : flouring of the gold, interferes or 60 in seconds in dissolved Gold sulphurized cyanide in K2S, cent,
cyanide
a
—
minutes.
62
Trans.
N.Z.
t Trans.
N.Z.
*
% Trans. Chromes."
N.Z.
Inst., vol. iii p. 216. Inst., vol. xxi., 1888. Inst., vol. xxi, 1888,
"On
the
Preparation
of Artificial
CHEMISTRY
THE
seconds
sulphurized 54
Gold
in
15
THE
PROCESS.
K2S,
dissolved
OF
in
cyanide
in
50
in
cyanide
in
36
minutes.
second
1
sulphurized
Gold
in
dissolved
K2S
minutes.
clean, dissolved
Gold,
washed
well gold was before being placed in the approximate times The
minutes.
12
potassic sulphide gold the unit,
adherent
clean
Making
dissolution
of
Sulpho-cyanides.
of
Action
from
cyanide.
the
in
cyanide
in
1:3:4:5.
are
It
—
held
been
has
by
some
of solutions of these in working metallurgists that the presence As the cyanide is injurious,retarding the dissolution of the gold. Bird of of much result Camp research, Godfrey Doveton, formerly tion soluthat that he has found informs a me Mills, Ouray, Colorado, containing potassium sulpho-cyanide up to a certain point than
active
more
was
solution
a
in
corresponding strength
of
2-50
with sulpho-cyanide present, and that even KCy, grams, the extraction of influence in solution 100 c.c. did not of KCyS in in salt The solution water, is a slow alone, unfavourably. solvent for gold. the same much result, and Experiments on mill solutions show he
has
quantities
of
of the
Waitekauri,
near
the
in
of
presence
able consider-
even
should
solutions
working Oxides
Manganese
the treatment
During
salt
sulpho of
Action
The
that
not
uneasiness.
any
cause
conclusion
the
to
come
parcel of
a
author
there
was
gold-mine,
Komata
the
from
ore
fouud
Cyanide.—
on
unusual
an
tion consump-
ore mullqcky, friable cyanide. quartz, coloured quite black by a large percentage of pyrolusite^ and cobalt. of nickel and wad, and containing a trace the made of determine afterwards to A series experiments were
the
cyanide
with
a
more
to
Further
cobalt
cyanide. was
It is
The
Action in
ores
solution
of
is well
the
of
dissolved
copper,
that
that
the
of heat
loss
alone,
silver
the
due
was
on
found
to
ing consum-
in
zinc
cobalt the
with
interfere
the
to
dissolved
the
but
substance.
readily,thus that
note
author
a
easily oxidizable
somewhat
tractor ex-
the
gold.
Oxygen-bearing
or containing copper the potassium cyanide,
in the
the
portion of pyrolusite parts
oxidized
influence
an
was
led
first
at
known the
interesting to the gold and like
and,
precipitationof that
which
precipitatedwith box,
It
soft
oxides
manganese
showed, however,
ore,
of
these
of
under of its oxygen in the presence of
research in the
the
cyanate*
portion readily so
results
the
that
conclusion
the
to
loss, and
of the
cause
consisted
The
of
ore,
Agents.— other base
base metal
necessarilyutilize
the
It
probable
seems
metal
would,
soluble from
greater
in
a
its preponderance
amount
of
16
the
available
the
gold
that
of
the chemists
of
the
That
special and
author in
South
use
seems
cases,
the
of well
an
that
established
by Western
reliable
would
ores
agent the
the
supply
containing
by*
of
conclude
to
would
oxygen-bearing
and
dissolution
reasonable
gold
reported America
is
agent
complex
results
Africa,
it
oxidizing
an
the
render
to
Hence
such
in
oxygen
beneficial. in
imperfect.
employment
deficiency be
and
tending
thereby
oxygen, slow
the
PROCESS.
CYANIDE
THE
is
fied justi-
experience metallurgical
Australia.
of
18
cyanide and the cyanide On
the
actual
gold,
coarse
extraction
—
an
containing
ore
results
The
from
ore
an
the
in
give
lower
cyanide works.
on
of
case
laboratory
extracted
—
those
author
made
Marlborough,
N.Z.
was
40
in
number
of
a
The
average while
the
battery the ore and dry-crushed through a 60-mesh investigation was screen, that fine enough showed reduced gold was a large portion of the amenable to pass to cyanide through the screen, and thus became
cyanide plant
60
over
At
sample
obtained
cent.,
per
tively compara-
the
where
than
under
successful
are
confidence.
with
laboratory experiments
will
the
practice in experiments
the
trials
working
adopted
be may in the
hand,
is hand-crushed
If the
extraction.
treatment
other
PROCESS.
CYANIDE
THE
cent.
per
the
treatment.
ACTUAL
THE
1. Procure When
bell-
about four and inches in diameter. bell-jars, a half clear jars are not procurable, lamp glasses or glass pint six
bottles, with well.
In
EXPERIMENT.
the neck
the
the off, will answer jar fit a cork, perforated
bottoms
cut
of each
quite
purpose with
one
hole.
short
length of glass tube, on the end of rubber few of pliableblack tubing. On the end the rate of the rubber of which tubing place a screw-clip,by means be regulated to a nicety. of percolation of the cyanide solutions can fix them the jars,and in a wooden 2. Now invert frame, so as to stand upright. In each jar place a thin layer of small rounded beans the size of French about the pebbles, pebbles place ; above
Through the which place a
an
inch
of
hole
a
pass inches
sand, and
coarse
above
this, half-an-inch
of
fine
sand.
of place a piece of loose scrim, the diameter the jar. This completes the filter-bed. of cyanide experiments are When a large number being made, a into three compartments, the three divided box to hold grades of be material for the filter-bed, should kept well replenished and
Above
hand.
at
near
fine sand
the
sample of the pulverized ore to be tested, Mix thoroughly, and carefully weighing, say, six or eight pounds. the original value. to accurately determine assay should if there is a serious Check always be made, and assays the assay and its check, amounting to over discrepancy between 3.
3
Next
cent,
per
form
the
of the
basis
When be
placed
value,
of the
hence
and the in
ore a
fair
a
procure
jar
in
be
greatest tested the
should
assays and
calculations
the to
fresh
final
condition
the that
The
made.
results
should
accuracy
is from
be
be
of aimed
the
assays
ments, experi-
at.
battery, or mill, it should the it comes from mill,
LABORATORY
when
except, of course, fineness, which
would
washed
twice
19
EXPERIMENTS.
the
tests
degree
the
determine
to
are
of
extraction. give the best economic be When the ore is hand-pulverized, a separate portion should reduced to through, say, a 30-mesh, 40-mesh, and 60-mesh pass of each sieve grade, respectively. Separate tests should be made affected determine what the extraction is extent to to by the as so varying fineness of the ore. and of the powdered into each 4. Introduce jar 10 or 12 ounces has been obtained by careful sampled ore, the value of which 6. Mark the jars 1, 2, 3, 4, 5, and assay. In the of 5. case tailings or ores containing iron pyrites, or metallic be base other sulphides, the samples in the jars should or
once
With
solutions
cyanide
used
solution
on
0*6 per
exceeds
antimony the
All
cent.
series
of
clean
would
phates. sul-
alkaline
dilute
very
soluble
any
wash
:
scale
for of
ores
of
class
any
try
both
seldom
ore
arsenic, and copper, when either of these
and will
the
have
latter
tried than
be
to
series
useful
a
of
—
tailings,or compounds, the most
the
of
silver,
solutions
With
or
ores
of all
event to
its
cyanide,
0-15%, 0-20%
advisable
Chapter IV.) the to as strength of the will depend this the much as on gold value ; but the strength of
0-1%, 0-15%, 0-2%, 0-25%, 0-3%
arsenic
the
as
the
ores.
contain
pyritic or
used,
stronger
case
With
be
can
be
consume
005%,
those
of
cyanide.
containing
instructive
mony, anti-
copper,
series would
be
:
—
0-25%, 0-3%, 0-35%, 0-4%. tests
being unsatisfactory,it and
stronger
already employed, according
as
weaker
solutions
the character
of the
ore
would
than
be
those
material
or
suggest.
may
It is necessary
experiments to
a
remove
laid down
sample as on a working
on
a
solutions
In
to
tailings
and
act
present
in
to
of the
character
is
rule
general
No
6.
acid
very
water
applied. (Test for acidity,see
be
may
clean
with
extract
7.
weight
used will
each
of to make ore new a number every ascertain the strength of cyanide solution of the
adequate proportion jar, already charged
of solution
as
of
ore.
The
gold
with
the of
excess
and
laboratory
silver
ore,
required contents.
add
solution
the is
same
required
the into filterlarge portion immediately finds its way and numbers the the the of Record jars strength of cyanide the that in each. the Regulate screw-clips so percolation A longer time take tried if the be at least thirty hours. may
because
bed.
an
To
to
with
a
first trials
are
not
successful.
With
testing highly pyritic material,
very
it may
dilute solutions, or be
necessary
to
when
continue
20
PROCESS.
CYANIDE
THE
longer before satisfactoryresults solution If the obtained. comes through too quickly, return are this time to percolate more allow it it again and slowly. wash with the 8. When is two complete, washings of leaching clean to drain a" rapidly as possible. water, allowing the wash- water wash-water when The is the no longer gives an complete washing the
leaching
alkaline
for six
days
or
even
reaction.
the strength of the spent solution to ascertain centage perThe and washings are solution collected of cyanide used. and measured together, then tested for cyanide. The by determining consumption of cyanide can be calculated solution and the strength of the combined making washings, and the
Test
9.
allowance
an
the
for
in bulk
increase
due
to dilution.
of cyanide is generally consumption shown less than that much by the laboratory experiments. different the cyanide and Sometimes washings are kept separate with and the addition of litharge (in the manner evaporated down described The under Assay of Cyanide Solutions),and the gold results by each, calculated separately. The actually extracted lesson the value instructive of successive afford an on washings. and washed the jars,dry, the leached from 10. Remove residues As the will probably residues mix thoroughly and again assay. 1200 1000 be excessively low-grade, it will be necessary to take or determination. calculate the Then grains for the assay age percenteach from of extraction jar by difference, recording the results On
and
scale
working
a
values
assay
the
follow
as
:
—
Value.
Original ozs.
Gold, .10
Value,
.£9
example
take
the
is
ozs.
4
4
0
3
6
83'9
18
4
89*8
simply
recovery
grs.
0
£0
0
of
a
proportion.
dwts.
4
12
.0
4
12
Extracted,
.200
would
the
extraction
ton.
per „
„
.
what
an
grs.
.2
ounces
As
gold.
Original gold, After leaching,
if two
89'9
12
of
matter
ozs.
Then
Percentage of Recovery.
Leaching. dwts.
12
0
calculation
After
grs.
4
2
Silver,
The
dwts.
extracted
were
be
from
100
from 1
2
ozs.
4
dwt.
12
grs.,
2
4 dwts.
ozs.
12
:
grs.
2
x
21
EXPERIMENTS.
LABORATORY
2
ozs.
:
100
:
89*9
:
cent.
per
100 =
89*9
cent.
per
2-225 of calculating the percentages expeditious method the in the weights of the of extraction laboratory-test is to use putation bullion, gold, and silver (in grains or grams) as the basis of comAn
and
easy
instead
of
the
extended
same,
dwts., and
ounces,
as
grains. Example
:
—
After
Original Assay.
^Z*
Extracted.
Leaching.
per
cent.
900
'0020
'0002
-0018
Gold,
•0018
•0001
0017
94-4
Silver,
•0002
•0001
0001
50*0
Bullion,.
.
£9
Value, The
calculation
2
0
£0
10
£8
3
•0018
x
For
'
For
x
94*4.
=
943.
100
50 9-1
•0002
and adopt Compare the results obtained extraction. the highest gives series of experiments it With Remarks. a 11.
—
percentage
=
Value.
8-587
100 =
the
100
•0018
Silver. x
x
90
•002
•0001
Gold.
•0017
100 =
For
94-3
9
:-
Bullion.
For
11
of
extraction,
or
rate
of
solution
the
will
dissolution
strength be
found of
which
that
the
gold, strength,
cyanide a this the of extraction rate strength The which solves disrapidly diminishes. strength of cyanide solution the of gold will depend on the character maximum percentage of cyanide is not The action of the ore. so-called selective in practice. the it is laboratory experiments as so apparent in in the On becomes evident of treatment working scale it soon a of cyanide of potassium that base sulphide ores a strong solution and small dissolves a a large proportion of the base metals tion proporsolution dissolves of the gold, while weak a large proportion a metals. small proportion of the base of the gold and a reaches and
a
that
maximum above
with
and
a
below
of
certain
CHAPTER
CONTEOL,
To
the of
operation and of
the
by
personal
of
supervision
:
standard
solution
of
silver
By
standard
solution
of
mercuric
3.
By
standard
solution
of
iodine.
Standard
the
of
The
depends
added
is
unites
with
forming This
a
is
of
by
any
cyanide
shown
AgN08
KCy
+
that
a
as
cyanide
mination, deter-
cyanide,
white
of
potassium equations AgCy
-
+
of
the
and :
still
may
silver
cyanogen
precipitate, which
KCy,
is
cyanogen.
solution
a
It
plants.
of
when
free
the
by
in
potassium
appearing
double
reaction
up
works.
the
for
estimation
fact
solution
silver,
a
the
on
dissolved
immediately
charge
made the
Solution.
adopted
volumetric
Liebig's
to
the
be of
chloride.
Nitrate
generally
modification
nitrate
accuracy
nitrate.
Silver
method
reaction
an
method
alwavs
used
be
is
—
By
is
with
volumetric
a
in
may
1.
This
chemist
methods
2.
By
by should
the
This
performed
foreman
solutions
volumetric
namely
a
standard
The
Solutions.— be
can
intelligent
any
different
Three
and
SOLUTIONS.
OF
Cyanide
simplicity,
great
estimation.
ANALYSIS
of
Strength
expedition
under
AND
TESTING,
Test
IV.
which be
is
sent, pre-
silver.
—
KN08
;
and
AgCy A
standard
molecular
solution
of the
of
weights
+
KCy=AgKCy2.
silver
nitrate
constituents
AgN08
silver to
-013
use
grams,
grm.
are
of
a
KCy.
the
—
130 13
=
decinormal
dissolved
:
from
=
17
nitrate
follows
up
2KCy.
saturates
170
With
as
made
be
can
in
solution 1000
c.o.
of
;
then
water,
if 1
c.c.
17 will
grams be
of
equal
CONTROL,
To
Make
dissolve
works, 34
Standard silver
of
grams
To
where in
Test
Nitrate
23
SOLUTIONS.
OF
Solution.
17
Take
—
nitrate
KCy
of
burette
a
2. Measure another
Silver
Solutions
Fill
1.
ANALYSIS
(triple crystallized if procurable),and litre In one (1000 c.c.) of distilled water. large, much dissolve to testing is going on, it is advisable then mark. litres in and two stoppered-bottle place ;
in
grams
AND
TESTING,
with
13
silver of
c.c.
and
burette
:
—
nitrate
solution
cyanide
transfer
to
solution.
tested
beaker.
smaller
a
be
to
from obtain
To
.
results
accurate
the
and
beaker Bun
3.
add
few
a
till the
white
beaker
is shaken
by KCy. Suppose
that
;
reaction off
divide
is
solution
The
For
to
of
result
of
burette the
when
opalescence
permanent
complete.
:
standard
of
c.c.
will
example
c.c.
re-dissolve
to
ceases
faint
a
the
cautiously from
just
when
is,
number
10.
13
iodide
potassium
solution
AgN08
precipitate formed
the
of
shake.
in standard
appears 4. Read
drops
the
represent
used,
solution
able avail-
of
percentage
and
—
KCy
sol. took
14*5
then
AgN08l
of
c.c.
—
1^-1-46%KCy. of
If
a
measure
and
titrate
of silver 10
is
strong solution off,say, 3 c.c.
or
standard.
silver
with
nitrate,
13
being tested, in order 4 c.c. of cyanide solution
would
c.c.
if 4
Thus,
require
19*5
to
AgN03
save
instead
of
required
c.c.
; and
6
13, c.c.
divided
19*5
by
1-95% KCy.
=
Even
obtained tions, be in testing strong soluaccuracy may those in the dissolving tank, together with a saving
greater such
of silver
as
nitrate, by measuring
and
diluting
this
diluted
above.
with
water
solution
Note
the
the
130
to
and
off
of
reaction, and
c.c.
with
the
of
c.c.
Then
c.c.
titrate
number
13
off
measure
silver
nitrate
of standard
solution
strong as
solution
13
of
c.c.
described
required
to
complete represent percentage of KCy in the strong solution, for since the 13 c.c. of dilute solution contained only a tenth of the original 13 c.c. of strong solution, there is hence need to divide the quantity of silver nitrate by ten. no To test the strength of very dilute cyanide solutions, measure off 130 the
c.c.
of the
number
will
give
130
c.c.
of the
of
c.c.
this
solution, of
cyanide
5+
100, and
100=0-05%
thus
KCy,
required
nitrate, and
silver
required by
of available
solution
the
with
titrate
standard
percentage
will
5
c.c.
KCy.
of
:
the
divide
result
—
standard, then
—
24
and
calculation
avoid
To
PROCESS.
CYANIDE
THE
the
reduce
of silver
nitrate
solution reading the burette, a standard 13 '07 .made grams* of silver nitrate by dissolving up with of water. To test a cyanide solution this, measure in
and
titrate
standard
required will
result
silver
with
If 10
be
the
of
c.c.
cyanide
10=0-5%
the
Two
—
should
floats
always
addition
The
reaction
In
due
to
Solutions," and
t Mr.
Silver in the
present
reduces
the
H.
the
the
solution,
The
a
cyanide
chemical
the
Erdmann
exact
reading.
per tested
cent,
solution
renders of
of
the
end
over-estimating
and
of
to
the
indicator
fulfils
the
silver
about
is
Cyanide Mexican copper
where
the
to
is the
nitrate
attack
the
thereby preventing an example,
copper,
As
cyanide.
free
Use
where
that
iodide
with
of the
measure
standard.
the
shows
an
combination
over-estimation
gram.
Chemist
Chief
of indicating the point purpose titrated all the free cyanide, and in
1-1 0th
danger
further has
to
nitrate
Titration
of
use
nitrate,
solution.
Virgoe, Company,
Recovery
the
—
; one
2
be
to
on
Walter
to
of
drops
"
and
:
silver
obtain
to
as
alkalinity of
the
the
solution
and
interesting paper
an
Gold
the
defined,
more
KCy
or
to
so
three
used
be
always
graduated
used,
of
c.c.
KCy.
for
one
be
be
of two
iodide
potassium the
should
burette
gram
should
and
solution,
cyanide
The
burettes
c.c.
by ten,
of silver
c.c.
c.c.
off 10 of
thus
KCy,
required 5
solution
divide
reaction,
be
can
1000
in
number
the
of available
percentage
5hRemarks.
the
complete
to
Note
nitrate.
mistakes
make
liabilityto
of cent, and containing per copper alone, may titrating0*52 per cent, of cyanide with silver nitrate of KCy titrate only 0*13 correctly if KI be used. per cent, finds that in Virgoe titratingpure solutions of potassium cyanide,
he
says
that
the
amount
when with
is
solutions
To
1. nitrate
present,
using
containing
grain
burettes
2.
Measure
off,from
be
tested.
Add
t
dissimilar
reason
addition
Solutions
by dissolving170
*
proportion,
very
but
whatever, lie shows
that
percentages
he
points
of
KI
out
before
the
of
bility advisa-
titration
of
copper.
Cyanide
When
this
difference
no
small
in
minimum
a
makes
indicator
For
obtained.
Test
used
even
of
amounts
are
of
0*3
of indicator
copper different
cyanide
to
a
solution
a
a
few
Thus:—
17:
Trans.
Inst.
are
with
used,
grains
in
burette,
drops 13 '08
Min.
:
and
Grain
make
Standard
up
a
solution
10,000 grains 130
grains
of
of pure
cyanide
of KI.
:
13:10.
Met., London,
Solution.
1901-1902.
of
silver
water.
solution
26
Remarks. but
With
—
with
the
with
simultaneous
iodine
is added
colour
so
long
(2.) To :
as
silver
obtained
results
Solution.
fact
that
when
a
solution
of
loses
its
Iodine
Solution.
the
Use
—
action re-
—
21 +
KCy
254
saturates
254
Therefore, to iodine, place
6*5
=
make in
When
in
water, and
place
a
(b.)From
bottle.
c.c.
solution c.c.
in
until
(d.) Read
a
off the
by 10, and required. Remarks.
—
of presence discoloured.
Make of
This
the
making
to
water
up
6*5
add
will
do)
carbonic to
when
yellow
not
be
the
all
in
cyanide
common
—
and is
slowly,
produced.
employed,
results is
solution
There use
are
in
two
divide
KCy
of
percentage
reliable
give
Solutions. in
colour
of standard
will
the
solutions
the
convert
bi-carbonates.
c.c.
does
acid
contained
iodine, cautiously of
cyanide
of
c.c.
this
alkalis,
into
result
Cyanide
pure
:
off
permanent
method
sulphides, or up
soda
standard
number
with
c.c.
iodine.
measure
tested, and
slight but
with
—
cyanide,
run
iodine
KCy.
mono-carbonate
commercial
1000
Then
grm.
burrette
and
the
grams cient suffi-
add
and
water,
to
up
25*4
out
dissolve
standard
the
ordinary
of
caustic
(c.)Now
'0065
=
with
be
to
of
c.c.
stoppered
another
(20
200
completely
to
burette
a
with
Determination
Actual
(a.) Fill
solution, weigh
make
1
(3.) The
solution.
dissolved,
is
in
decinormal
a
standard
a
a
ICy.
+
65.
beaker
iodine
the
KI
=
potassium iodine frequent shaking.
methods
the
on
Standard
up
of
the
potassium cyanide, the iodine undecomposed cyanide remains.
any
not
number
a
of
one
Make
the
so
do
alkalis
made
and
Iodine
depends
to
has
methods,
Standard
method
it is not
impurity,
Caustic
author
delicate,
is very
throughout.
same
By
reaction
much
working cyanide solutions, by
chloride
mercuric
This
The
reaction.
practicallythe
To
this
method.
nitrate
tests, with
and
nitrate
(1.)
substances
pure
silver
the
as
interfere
were
PROCESS.
cyanide solutions, containing
reliable
of
CYANIDE
THE
in
muddy
the or
different
cyanide plants.
CONTROL,
OF
ANALYSIS
AND
TESTING,
27
SOLUTIONS.
of solid cyanide salt is added requisiteamount the in others, sump-solution ; working strength is made up solution the tank the from to dissolving by adding strong sump In
some
to
the
the
cases
solution. The
exercises
following
render
will
methods
these
clear
:
—
1 lb. of pure KCy dissolved in 100 lbs. of water gives a 1 per cent, solution have a vat containing 100 cubic feet of ; therefore, if you make
to
water
up
lbs. of pure
to, say,
0*6
100
62£
KCy.* Thus
and
if 100
require
require 37*35
would
cent., you
per
lbs.
of
x
water
6225
=
lbs. of
0*6
require
water, 6225
KCy,
lbs.
lbs.
would
—
100
6225
:
:
0'6
:
:
x
6225x0-6 o7.q*iv0 35 37
-
lbs-
ioo
Commercial to
use
cyanide is seldom greater quantity to make
a
Suppose
the
crude
78 100
78
:
100
of
cent,
per
34*35
:
:
have
required strength.
the
up
contains
KCy
would, therefore,
; you
pure
then
KCy,
:
—
7
:
37-35
x
=
lbs. crude
KCy.
will do for
making
48
78
The
quantity solution
would
of were
Then
cyanide solution. required.
if 100 4
of calculation
form
same
of water
ozs.
Suppose require
:
^-^-5 =
to, say, solution
proceed
have
0'5
a
per
from to
ozs.
ozs.
of
of
a
any 0*5
required per
cyanide, how
cent,
much
require ?
ozs.
100
If you
0*5
4
up
make
0*2
per
cent.,
0*5
cent,
subtract
:
:
0*5
480
as
directed
x
:
=
9-6
solution
and
x
the
0*2
cent., leaving 0*3
per up
002
4
in the
grains.
you
per per
wish
cent,
cent,
to
make
already required.
it up in the Then
preceding paragraph.
Exercises.
(1.) I
have
4000
lbs. of sump *
See
Constanta
solution
at
end
of
containing Chapter.
0*2
per
cent.
28
THE
of available
solution,
I
which
KCy,
how
wish
additional
much
PROCESS.
CYANIDE
100 4000
:
0*5
a
required
be
0-3
:
to
up
will
KCy
4000
:
make
to
cent,
per
?
x
:
-3
x
lbs. pure
12
=
KCy.
100 If then
:
KCy
crude
your
salt
contains
only
82
of
cent,
per
KCy,
—
12xl00aaU.6
crude
lbs
KCy
required
82
(2.) How should
be
lbs. of solid
many used to
solution?
Ans.
make
10
up lbs.
119*46
—
of 75 per cent, 0*4 cent, per
cyanide salt of
tons
a
lbs. of solid cyanide salt of 82 per many make 5 tons of a 0*45 be used should to per up solution solution, using a sump containing 0*15 per 40*97 lbs. Ans. for making up?
(3.)How
strength working strength working of KCy
cent, cent, cent,
—
(4.) How should
be
many
used
Solution. mixer's
—
rule
make
to
solution, using
14
per
cent,
10
tons
of
a
up
0*18
per is easiest
a
This of
of
lbs.
cent,
:
00
\S
"40
working
/\
'18
sump
+
*2 2
—
'40
13*60 Proportion of weak Neglecting decimals, =
then:
1360
of strong
22
lbs. of the how
1382
have
we
strong
1360
of
be
give 1382 required for
22400
of
strong.
required mixture,
solution; lbs. of
10
:
taining con-
if 22
mixture?
of the
22
:
therefore,
required mixture,
the
tons
(10x2240)
1382:
proportion
=
the
weak
solution
will
lbs.
many
and
solution
1382.
=
lbs. of
or
solution
—
22
+
parts
cent,
for
"
by
per
thus
Strong solution 14 Working solution
Here
working making up? Alligation," the tea-
solution
sump
solution
cyanide
0*4
a
determined
proportion,
stock
: x
22
"x
356,58
=
1382 The
answer
(5.) How used
to
make
0*12
sump (6.) How
used
to
make
is,therefore, 356*58 many
lbs.
up
of
lbs.
22
per
cent,
9 tons
of 0*5
per
cent,
solution
for
making
up
many
lbs. of
up
10
tons
a
a
twelve
of
a
0*6
?
stock
solution
working
Ans.
per
cent,
per
cent,
—
solution, using
351*27 stock
should
be a
lbs.
solution
should
be
working solution,using
CONTROL,
0*15
the
vat.
of
solution
6.
—
solution, thus:
—
'80
20
the
tons, thus
0*8 solution
a
much
4 tons
of
of 0*8
already
the
working cyanide
cent,
per
45
+
\
*60
of the 4
65
=
working
'15
sump
of
'45
+ :
(0*8 already in
solution
solution
proportion
=
of strong.
—
mixture.
required
strong
tons
'60
/ "";' /\
=
mixture,
how
out
the
'20 Proportion of weak Neglecting decimals, then
if 45
drawing
—
Strong solution solution Working
Then,
of
tons
Before
up?
lbs.
find
from
up
4
29
SOLUTIONS.
OP
making
359*74
First
made
be
can
Ans.
No.
for
first utilize
solution
solution
Solution
solution
sump
stock
the
from in
cent,
per
ANALYSIS
AND
TESTING,
cent.)give
per the
65
of the
tank
solution
will
required give 5*77
:
—
45
4
:
:
65
:
: x
4x65
577.
=
45 And stock
10
5*77
—
solution,
4*23
=
thus
:
tons
made
be
to
from
up
the
12
cent,
per
—
Strong solution Working solution
12*00
\/
'60
/\
*1 5 sump
working
solution .
*60
1 1 '40 Proportion of weak : Neglecting decimals
-45
+
=
=
solution
proportion
of
strong.
—
1 140 if 45
Now, lbs.
of the
lbs.
+
the
of
45
1 185
=
stock how
required mixture, 1185:
of mixture.
solution
(4-23x2240)
4*23
x
2240
x
(12 will
much :
:
45
per 4*23
cent.) give tons
1185
require ?
: x
45
359.741bg
=
1185 ,
TO
(7.) How 6 tons
of
dilution? Solution
DILUTE
CYANIDE
of a 0*45 tons many 0'8 per cent, solution
a
Ans. :
—
10*66
SOLUTIONS.
would working solution for cyanide make, using water cent,
per of
tons.
—
•45
:
*80
:
:
6
: x
8_0|_6 10.66. =
45
30
THE
(8.) How cyanide would cent,
per
:
of
tons
many 8 tons
of
solution
cent,
per
Ans.
make, 13*71
—
of
solution
working
cent,
per
using
0*12
a
tons.
—
Strong solution Working solution
of the
if 28
8 tons
"60
will
\
=
/
"40
working solution
"12
sump
""-:
"40
of weak
Proportion
Now,
0*4
a
0*6
a
PROCESS.
for dilution?
solution
sump
Solution
CYANIDE
/\
*20
+
*28
20
+
28
solution
strong
give 13*71 28
8
:
^i?
:
:
of mixture.
48
=
48
required
the
of
ture, mix-
—
48
x
:
13*71
=
of strong
proportion
=
give
tons, thus:
solution
tons.
28
(9.) How of
tons
To
for
Test
formed of
0*7 per
a
solution
tons
many
cent,
dilution
?
of
0*6
a
solution Ans.
10
—
Strength
the
make,
of Crude
KCy.
is very is lixiviated in a impure, and metallic iron, yielding the yellow finely-divided
product
which
is
as
KCy is hoofs, clippings This
carbonate. vessel
containing prussiate of potassium all of starting-point cyanogen
the
compounds. Crude cyanide of potassium the yellow prussiate,thus :
sump
Commercial
—
any nitrogenous organic bodies, such wool, and blood are fused with potassium
(K4Fe6Cy6),
cent,
per
8
tons.
when
hides,
would
solution
cyanide using a 0*2
cent,
per
is formed
the
by
of
action
heat
on
—
K4FeC6£T6 The
chief
impurities
iron, alkaline
sulphides in
4KCN
=
in commercial and
carbonates,
FeC2
+
N2.
+
cyanide
black
are
alkaline
sometimes
carbide
of and
chlorides
small
quantities. the strength of the solid cyanide salt, for the it contains, proceed as follows : free or available KCy which cake of Break KCy in two, and select a piece,say, a pound a (1.) the whole thickness the cake in weight, showing in of To
accurately
test
—
section. this
(2.) Reduce
pound pulverize to
f urthur
(3.) Weigh (4.) Dissolve
out
(5.) Measure nitrate
standard
described.
Note
a
of
1 gram
in pure off 13
to
powder, sample well, moderately fine powder. powdered and sampled KCy.
water c.c.
a
and
of this solution number
coarse
make solution from of
c.c.
to
up
and
100
c.c.
titrate
burette
a
of
and
standard
as
with
silver
previously required to
CONTROL, form
permanent
a
the For
example
:
13
of
c.c.
and
10
by of the
this
crude
will
give
salt.
solution
KCy
31
SOLUTIONS.
OF
; divide
1 gram
in
KCy Suppose
then
ANALYSIS
p.p.
of
amount
of standard,
AND
TESTING,
7*5
required
c.c.
:
—
7*5 —
which
is
equal
75
to
Yi'orks where be
effected
by
It
has
used
for
a
with
the
the
in
of
contents
cyanide
Method
I.
methods
II.
care. over
of both of
salt.
gold
and
and
silver
must
Several
reliable
give
very
III.
large
daily
which
of
in
accurate.
is in
and
solutions
made
are
expeditious given below, all
are
crude
SOLUTIONS.
both
determination
is necessary and III. are
in the
KCy
determinations
many
ordinary advantage
the
1 gram,
CYANIDE
gold
method
methods
alternative
results
great
a
of
OF
of the
estimation
in
KCy
cent,
per
ASSAY
THE
The
*75
=
—
common
that
use.
it
be
can
which
contents,
Methods II. gold ores. devised F. Crosse, by Andrew processes well known South African the chemist. Method metallurgical IV. is a copper H. Virgoe for sulphate process used by Walter for the is It some rapid assaying of cyanide solutions. years Like recommended method be I. it can used for by Crosse. silver contents. valuation of gold and silver
case
argentiferous
nitrate
I.
Method
—
(1.) Measure
half
small
bulk
flame,
or
the
rub
in
sides
furnace
lid.
so
the
solution
the
iron
down at
solution
of
round
a
the
on
salts
(2.) To
pint
a
to
as
and
evaporate
slowly
to
a
drying-dish, over a As the evaporation proceeds, Bunsen
collect
the
whole
of
solved dis-
the
bottom.
add
600
grains of litharge. Mix well; to cautiously dryness. evaporate transfer to a clay-crucibleand with mix 200 (3.) Then grains of 100 48 grains of soda, and glass-powder, grains of argol of Cover with little a potash). borax, and (bi-tartrate When
fuse.
If the
bullion.
When
weight
of
the
end
of
the
ton
of solution.
and and
contains
ore
the
per the
pour
lead-button
the
(4.) Cupel
fused,
and
gold chapter
resultinggold
is
allow
weigh
the
resulting
silver, part
of silver to
cool.
to
; then
ascertain
weighed
with
so
as
refer the
gram
to
to
bead
of
determine
the
quantity weights,
table of
at
each
refer
to
32
CYANIDE
THE
the
Gram
end
of
Table
when
and,
;
in
PROCESS.
grains
Grain
the
to
Table.
(See
chapter.)
of determinations have be to large number form efficient evaporatmade, ordinary enamelled plates and mugs ing be dishes ; in this case also the stirred into the litharge can solution before the evaporation begins. At many the cyanide works cyanide solutions are assayed by evaporating a measured portion of the solution in a boat of sheetlead and then the scorifying the residue, and cupelling. When solutions are cyanides the results are charged with base metallic the solution reliable when is evaporated with not as generally so fused in a clay crucible. litharge and afterwards Remarks.
When
—
Method
II.
(Crosse). —
(1.) Measure nitrate
solution
should
be
after
a
half
a
until
a
added
little at
a
addition.
each
pint of cyanide solution, to form. precipitate ceases the
All the
time,
gold
and
in
the
The
solution
the
add
and
solution
silver
well is
silver salt
shaken
precipitated
argentic-auric-cyanide. clear tion; soluoff the (2.) Allow the precipitate to settle ; decant and filter with 200 dry the precipitate and mix grains 100 and 48 100 soda, litharge, grains glass-powder, grains grains of argol. Fuse, pour, and cupel the lead-button. bead the of bullion the from (3.) Extract cupel, flatten, and weighing. part without the results. (4.) Weigh the resulting gold and calculate
as
Method
(1.) Put
III. (Crosse).*— Pour
it in
cyanide cupboard with
500
c.c.
stink
a
(2.) Add
nitric
of
acid
till the
(3.) Boil 15 minutes. add £ gram (4.) Then (5.) Filter ; fuse the usual
a
into
shows
dissolved
filter-paperand flux;
evaporating
an
dish.
good draught.
solution
of silver
litharge, and
with
solution
then
acid
an
in silver contained
cupel
and
reaction.
nitrate.
precipitate as weigh resulting
bead.
Method
IV.
(1.) To
a
(Virgoe).—
litre of solution
add
excess
of weak
sulphate
of copper
solution.
hydrochloric, nitric,or sulphuric acid. and The is white flocculent, precipitate, which The bluish of all the gold and silver. contains or greenish colour of copper the filtrate indicates that excess sulphate has been added.
(2.) Acidify (3.) Filter.
*
1902.
The
Journal
with
of
the
Chemical
and
Metallurgical Society of S.A.,
May,
34
attention.
much
object
the
devoid
of
in most
THB
CYANIDE
Many
useful
The
"
"
method
This
been
used
much
is
tion every-day applica-
of
laboratories
the
in
Cyanide.—
of
Consumption rapid and cyanide with
affords
and
Cyanide Company,
for
methods,
reliable
devise
to
formulated,
been
have
yet capable
refinement,
cyanide works. Test Shaking
in
schemes
having
cases
much
too
PROCESS.
Cassel
the
of
fairly approximate
a
classes of different consumption of and It is useful for comparative purposes, as a preliminary ore. the suitable most of strengths of cyanide determining means for laboratory experiments. solutions and of the ore place in a stoppered bottle (1.) Take 200 grams with, for example, 100 c.c. of a 0'5 per cent, cyanide solution, and shake
the
of
estimate
for
with
Ores
Test
(1.) Weigh in
water
(2.) Fill
and
burette
a
grams
with
standard
a
the
jar
(litmus) paper. (3.) Every c.c.
of the
soda
of caustic
be
wash
a
to
the
added
cyanide
Standard
Make
until
0*2
posed. decom-
acidity by
—
shake
up
solution
of
the
with
250
of
c.c.
to
every
used
will
of
ton
soda, and is neutral
reaction
solution
titrate test
to
represent
0*1
(or tailings)in
ore
a
Solution.
soda
in
1000
c.c.
10
Dissolve
—
of
pure
(or
grams
water,
and
paper
should
place
bottle.
secure
Remarks.
the
During
—
dipped in clean, pure adhering particlesof ore Tests
Alkaline
for
titration, from
water so
that
the
Sulphides
litmus
the
time
in
time
to
reaction
to
be
may
Cyanide.
—
be the
remove
clearly seen. phides sul-
Alkaline
injuriously in cyanide solutions during leaching, and all soluble important to detect their presence. They are act
is
lb.
treatment. Soda
grains)of caustic
154*3 in
in
soda
before
To
or
for
ore
Acidity.
and
ore
consumed
the
test
portion of the
a
If it contains
KCy. been
up,
for
off
glass-jaror cylinder.
ore-solution
the
has
cent,
of
; draw
for
test
Tailings
224
out
tall
a
0*3 per
settle
cyanide is used given below.
method
Feldtmann's
To
then
much
(3.) When
to
pipette and
a
KCy,
of
cent,
per
of bottle
contents
solution
clear
minutes.
twenty
(2.) Allow
it in
water. First
Test
To
the
clear
cyanide solution alkaline be sulphide present, sulphur will to the solution. a cloudy appearance
an
Second coin. This
:
Test It
and
will the
—
:
—
In
become
the
clear
black
preceding
test
solution
place
and
tarnished
will
not
detect
if
add be
a
a
a
little acid.
If
liberated, imparting clean, bright
silver
sulphide be present.
minute
quantities.
CONTROL,
Third
Test
solution
The
—
solution.
If the
quantity, Fourth
the
of
solution
a
will
When
—
by
assume
acetate, is added
to
present,
solution solution
a
of
a
nitro-
acid
nitric
the
to
a
cyanide minute
in
even
colour.
purple
brilliant
a
dilute
a
is
the
of
means
nitro-prussideto
of
sulphide
alkaline
:
is
test
35
SOLUTIONS.
formed
solution
Test
as
or
an
OF
by adding a little ferri-cyanideof potassium.
drops
few
a
ANALYSIS
delicate
most
are
of ferro-
Add
such
:
These
prussides.
AND
TESTING,
lead
soluble
containing an lead sulphide soon
salt,
alkaline
forms. precipitateof of free When alkaline in the the sulphide exists presence will and carbonate white lead of cyanide, a cyanide precipitate of lead acetate, thus tending to immediately form on the addition render the lead sulphide precipitateyellowish or nut brown.
sulphide, a
blackish
brown
ANALYSIS
THE
OF
(Feldtmann From
5
dissolved The lead
10
to
in
or
and
water,
solution
of
—
Bbttel.)
and
of
grams
the
insoluble
the
agitated
is
carbonate
more
SOLUTIONS.*
CYANIDE
with
a
slightly
course
in
filtered
if any,
matter,
small
cyanide
commercial
quantity and
excess,
are
off.
precipitated
of
filtered.
The
and ferred sulphide, is transprecipitate,consisting of lead carbonate of with few c.c.'s of a solution to a a flask, and covered sulphides, sulphocyanides, or potassic or sodic cyanide free from be prepared from potassic ferrocyanides. This solution may pure distilled sodic hydrocyanic acid. or hydrate and a solution of pure add beaker the To the mixture in hydrogen peroxide in slight excess
i.e.,three
—
times
four
or
as
much
is needed
as
to
whiten
should precipitate. (The hydrogen peroxide for this purpose and ether be purifiedby agitation with evaporation of the ether in a water-bath.) of manganese A small peroxide is then quantity say \ gram two the mixture minutes, after agitated for about added, and with solution is filtered off, acidified the which sulphuric acid, the
—
—
N
and
titrated
potassic permanganate.
with —
—
N 1
c.c.
of
potassicpermanganate 0*000182
or
grm.
The
potassic permanganate potassic sulphocyanide. 1 *
Paper
read
c.c.
before
=
may
0*000053
potassic sulphide. be standardized by
-0001618 the
equals
Chemical
grm. and
grm.
means
KCyS. Met
Society
of S. A.
sulphur
of pure
36
CYANIDE
THE
Estimation solution
of
add
carbonate, Deduct
the
equals
of
this
of
amount
Estimation soda
then
titrate
above
; the
The
HCy
AgN03
of
c.c.
with
KCy
0-0414
=
and
solution,
free
from
KCy.
for
as
The
the
difference
HCy.
here
Add
and
KCy KCy*,
as
of
KI
pure
solution,
HCy,
found
as
less 7 '9 per
calculated
is
of
excess
drops
few
a
Deduct
K2Zn(Cy)4
found
as
Titrate found.
Cyanides.—
AgN03. is
soda,
or
of
c.c.
present.
double
difference
KCy
under
cent.
K2Zn(Cy4),
to
as
:
—
KCy
x
0-9493
organic
parts of
Estimation
is
matter
Add
K2Zn(Cy)4.
=
92 -1
for every
or
50
to
amount
c.c.
of
acid. of
50
-To
potash
of
carbonic
the
1
caustic
of bicarbonate
excess
or
from
Acid.—
Hydrocyanic
solution
a
PROCESS.
add
7 '9 per
to this
total,
of
cent,
7*9 parts.
and
Ferro-
Sulpho-Cyanides.—
shake
present,
with
powdered
When
quicklime
and
filter. A
is filled
burette 10
into
run
with
until
H2S04 50
of the
c.c.
half
about
c.c.
the
then
x x
=
(x) 1 (z) 1
be y
-
c.c. c.c.
with
the
Vioo normal Vioo normal
In
Mr.
blue
is
required
KjM^Og K^Mo^O^
ANALYSIS
scheme
(5.) (6.) Extracts
H2S04 shaking for the separated from The
oxidize
0'003684
filtrate
is
ferro-cyanide,
M.
the
The
ferrocyanides
The
zinc
from
Paper
KCyS.
grm.
*
SOLUTIONS
Green,
following
K4Fe(Cy)6.
grm.
0*0001618
depend essentiallyon
used
Green's
=
A.R.S.M.) alkalimetric
constituents
(1.) The total cyanide (2.) The protective alkali (3.) The alkaline or alkaline-earth mono-carbonates (4.) Alkaline
*
with
After
washed.
to
CYANIDE
OF
(by Leonard tests
poured
in.
z.
THE
The
is acidified
K2Mn208.
permanganate
c.c.
chloride
precipitate
normal 1/100
analysis, and strongly acidified
K2Mn208
Prussian
the
for
just discharged.
sulphate or cyanide solution
minute
a
titrated
Let
is
solution
cyanide
1/100Normal
colour
liquid by filtration,and next
the
of ferric
solution
A and
20
or
with
determinations. are
estimated: =T.
hydrates
=p. h.
=
=N. =S. =
read
before
the
Inst.
Min.
and
Z.
Met., London.
—
TESTING,
CONTROL,
The
methods
depend
(I.) Potassium (2.)
That
ANALYSIS
the
on
facts
ferrocyanide
I
c.c.
solution
of
zinc
a
when
—
phenolphthalein. potassium ferrocyanide precipitates to
zinc
from
dilute
neutral
a
salt.
dilute
a
:
is neutral
decinormal
c.c.
37
SOLUTIONS.
OF
that
decinormal
of
0*75
(3.) That
AND
neutral
solution
of
salt
zinc
a
is
carbonate of sodium excess precipitated by adding an alkali of carefully solution, the excess being afterwards neutralized the addition of to phenolphthalein, by decinormal of acid, a precipitate of basic zinc carbonate The almost constant tate precipicomposition is obtained. obtained
in this way
is the
normal
carbonate.
basic
with treated an hydrate or carbonate, when cyanide ferroforms zinc excess potassium ferrocyanide, the and carbonate, potassium hydrate or alkalinityproduced being proportional to the precipitate acted This reaction does not on. immediately proceed to the end, as at first only a portion of the alkalinity is
(4.) That
zinc
of
formed
The the to
total the
; but
if this
amount
of alkali
reaction
taking
Actual
Analysis. This
cyanide.
solution
to
be
is
be
neutralized
formed,
little time
a
is
tested
and
so
the
of
excess
finish, the
is that
first estimation
—
an
to
on
further
a
the
completion.
for
(1.) The performed in
acid
with
usual
potassium iodide, and titrating with silver yellowish cloudiness appears. permanent until there the end-point is not reached
nitrate It
and
till
a
distinct
a
a
little
distinct,
noted
be
must
is
by adding
way
soda
caustic
of
that
yellowish
cloudiness. much
Where
zinc
cloudiness, probably is sometimes
and due
produced
be
ferrocyanidesare to
the
precipitation of the
before
present,
true
"
a
faint, white
zinc-ferrocyanide,
end-point."
This
must
"
end point the yellowish disregarded, the true occurring when This is the cloudiness,due to silver iodide, is permanently formed. solution, and a only definite end-point in titrating such a large of sodium excess hydrate does not appreciably alter it. In the second the alkaline and alkaline-earth test (2.) hydrates half the the plus mono-carbonates, viz., "protective alkali," is determined. This of Clennel's. is a simple alteration test Excess the of potassium to solution, and ferrocyanide is added then
"
twice
the
of silver
amount
total
cyanide, viz., sufficient does cyanide. A slight excess chloride,
some
cyanide
or
or,
if
ferrocyanide.
no
The
nitrate to not
precipitate matter,
chlorides zinc
all
to
necessary
are occurs
the
indicate whole
the
precipitates sulphopresent, some in the precipitate as as
it
merely
of
the
38
ferrocyanide, and
the
PROCESS.
CYANIDE
THE
hydrates and
alkaline
carbonates
left in
are
solution.
decinormal
greenish The
than
and
identical
an
the
cyanide, towards
of its
acted
the
titrated
with
the
faint
acquires of ferrocyanide.
excess
alkali."
by only adding
nitrate
indicate
to
necessary
little
a
the
leaves
potassium silver-cyanidein solution, there titration is a slight chance on by the acid forming AgCy, and setting free the acid required, and obscure slightlyincrease
close
would HCy, which the end-point.
(3.) In
silver
of
this
the
being
third
acid
of the
alkaline
the
test
hydrates
is first added
chloride
of barium
excess
the
is obtained
result
amount
but
till it
or
indicates
Usually total
colourless,
till
solution
the
tinge produced by the "protective
yellow
result
more
acid
nitric
and
added,
is then
Phenolphthalein
and
precipitate the
An
estimated.
are
solution
the
to
carbonates),and
(sufficient ure proced-
then
the
sulphates The result obtained is repeated. indicates only the alkaline hydrate. In the event of no hydrates being present, bicarbonates probably exist be in solution. estimated They may by adding a known of standard sodium ing, amount hydrate, and repeating the test, allowin calculating the results, for the amount of hydrate added. is that of the total cyanide + chlorides (4.) The next estimation + sulphocyanides + ferrocyanides + any other salt precipitated This by silver nitrate before the precipitationof chromate. test, for the in is not though itself, necessary subsequent important to
the
in
last
determination The
test
of
drop
the
solution
to
neutralize
is titrated
reddish Towards
goes is due to
silver
till there
nitrate
end
of the
again slowly the
fact
reddish
titration,the
shaking
on
that
the
and
up
with
silver
ferrocyanide
when
the
(5.) acid
reddish
The
Sufl"cient for
zinc
is formed.
fifth estimation
faint
a
the
manent per-
necessary
zinc
in the to
silver
a
chromate,
appears,
few
seconds.
nitrate
consequently
end-point
The
is decided
to
in
Then
solution. the
and
of the
is added
precipitate
indicate
standing
the
on
silver
some
when
however,
ferrocyanide,is decomposed,
is that
carbonate
basic
enough already nitrate
the
colouration
sodium the
is
colouration
of the
action
precipitated zinc ferrocyanide is slow, chromate is temporarily formed; this shaken
to
the
and
well
is first added
protective alkali). Then is added, and potassium chromate
of
with
test
colouration.
the
only
This
in the
strong solution
a
second
used
sufficient (viz.,
one
and
zinc.
of acid
amount
solution
the
of
total
therefore
only
and
occurs
permanent.
zinc
the
ferrocyanide. supply enough carbonic
case
twice
-
there the
cyanide
should amount
is added
not
of and
be
silver the
CONTROL, whole
is
TESTING,
well
shaken.
silver
cyanide, precipitate some The
the
slight
any chloride.
will
zinc
All
and
ANALYSIS
AND
OB1
cyanide
is
now
of silver
excess
3d
SOLUTIONS;
precipitated as will merely nitrate
been
have
partially precipitated as ferrocyanide der by ferrocyanide originallypresent in solution, but the remainwill have been basic there precipitated as a oarbonate, and will be alkali of in solution. This the an excess alkalinity is neutralized of decinormal acid. by the addition During this neutralization the basic zinc carbonate gradually acquires its normal 3Zn the neutralization composition (HO)2.2ZnC03, and the
be
not
must
The
hurried.
colour
show
of the of
trace
a
pink,
neutralization of
acid,
at
a
above
the
precipitate must
standing a minute frequently shaken. apparently complete, it is best to
is
shake
solution
even
on
flask should
of the
contents
clear
well
up
and
add
then
from
In add
burette,
a
aud
two,
or
be
not the when
fact, another
c.c.
drop
a
or
so
N
time,
venient
solution
a
strength),till
.
sodium
of
the
carbonate
(roughly
con-
a
-
shows
again just
clear solution
is —
pink
a
colour. All
the
zinc
which
the
precipitateas phenolphthalein.
added,
the
forming
basic
If
now
zinc
of basic
an
carbonate
and
end
of
in
now
to
be
ferrocyanide
ferrocyanide,
the
to
the
present.
the
again slightly,so
returns
reacts
with
alkalinity proportional
alkalinityis then titrated zinc less what representing the ferrocyanide originally present. the
potassium
is
is neutral
solution
the
of
excess
carbonate
This
Towards
and
carbonate,
ferrocyanide
zinc
amount
basic
ferrocyanide
precipitated as
is not
that
a
been
has
titration
acid,
decinormal
with
the
little
result
precipitated by
colour time
the
discharged
is
for
is necessary
the
and the
determination. last
(6.)The added
in,
as
in the
well
same
shaken.
cyanides whole an
in the
will
of the
excess
determination
previous amount
The then zinc
of alkali
is of the
test as
was
; then
used
zinc.
silver in
Sodium
solution
nitrate
test
No.
4,
is
carbonate
and
the
is
run
flask
ferrocyanides, chlorides, sulphocyanides and have been precipitated as silver salts, and the will have been precipitated as a basic carbonate,
remaining
in the
solution.
This
is naturalized
of ferrocyanide added, and precisely as in the last test, an excess acid. decinormal the alkalinityproduced titrated with This result consequently represents alkalinity proportional to metals the whole the It includes of zinc. acting similarly to and if present in small quantity. zinc, such as cadmium, copper
40
CYANIDE
THE
Summary.
the
with
described,
(1.) Take and
50 little
a
till there
nitrate
of
c.c.
a
distinct
50
(2.) Take
c.c.
of the Kun
thalein
with
and
titrate
then
50
c.c.
of
ferro-
potassium Add
nitrate.
phenolph-
till colourless.
c.c.
p
=
Add
of solution.
BaCl2 solution, and
of
excess
potassium ferrocyanide.
of
excess
drate hysilver
with
—
Result
(3.) Take
acid
nitric —
sodium
Titrate
excess
of silver
c.c.
—
c.c.
Add
solution.
in 2T
cyanide solution.
T
=
tests
yellowish cloudiness.
permanent
Kesult
:
of
excess
solution.
iodide
potassium is
Add
solution.
the
the
of
following is a short summary solution of etc. taken, quantities
The
—
PROCESS.
Run
2T
in
c.c.
silver
of
N add
nitrate,
and
phenolphthalein
with
titrate
nitric
till
acid
—
colourless. Result
(4.) Take
50
c.c.
h
=
c.c.
Add
solution.
of the
2T
of silver
c.c.
nitrate,
N then
of
of
c.c.
p.
-
is
faint
a
Result
(5.) Take
50
solution of
silver
added)
nitrate,
well.
shake
with
silver
nitrate
Nc.c.
=
10
about
Add
Run
(roughly decinormal). and
strong solution
a
colouration.
(Total AgNo8
of solution.
c.c.
titrating
reddish
permanent
of
drop
one
continue
and
potassium chromate,
till there
Add
acid.
nitric
—
in
of sodium
c.c.
2T
bonate car-
(see Test
c.c.
Add
phenolphthalein,
clear
solution
1) and
N neutralize
with well
Shake
-
during
intervals
at
till the
acid
nitric —
the
neutralization.
up,
and
is colourless.
Add
about
N 1
c.c.
nitric
more
-—
acid,
shake
then
add
a
solution
of
N
sodium
drop, Add
(roughly
carbonate
till the
clear
excess
of
strongly
solution
is --
is
-
convenient
a
just faintly pink.
potassium ferrocyanide. to phenolphthalein.
alkaline N
Titrate
with
nitric —
-
acid
strength),drop by
till colourless.
Result
=
S
c.c.
The
solution
becomes
42
and
potassium,
of
nitrate
PROCESS.
CYANIDB
THE
3
(1-1).
sulphuric acid
dilute
of
c.c.
shaking up and allowing to stand for 15 minutes, titrate in solution an atmosphere of coal gas with a hyposulphite of sodium is equal to 0*25 of which containing 7*75 grams per litre,1 c.c. liberated. for the iodine m'grams of oxygen is apparently The iodine is that no peculiarityof the reaction iodine But colourless. liberated,and the cyanide solution remains After
has
liberated
been
to
same
form
compound,
unstable
very
a
proportion to the plus the quantity to be subsequently allowed for, and oxygen estimated be by the hyposulphite solution, using a starch
iodide free can
in
any
about
0*3
liberated
iodine
c.c.
ferrous
pure shake
under
solution
of the
sulphate
lime,
coal gas
all the
free
in the
oxygen
add
examination,
and
the
filter into up well and is passing, the precipitated ferrous
caustic
the
estimate
to
and
—
400
grams
the
it is necessary
course
by the reagents, nitrates were present in the cyanide solution. in the following manner made is easily :
correction
Take
is in exact
amount
Of
for
required
case
This
the
indicator.
an
as
correction also
and
of cyanogen,
solution
it
all the
weight of through which
same
flask
a
to
will
hydrate
sorbed ab-
have
solution.
cyanide
method test the above good many experiments were and the following will be a good example : A Winchester partly filled with a sample of an quart bottle was well shaken for some ordinary working solution, the bottle was made
A
to
—
in order
time The
to
determination 292
c.c.
required
to
unite
Then
400
c.c.
and
the So
iodine
made
He under bottle
—
liberated
m'grams In
13*4
that
solution,
with
oxygen
the
as
13*4
with
oxygen.
described, using a pipette of hyposulphite of soda c.c.
the
determination
oxygen
interestingexperiments on the by sands and spitzluten concentrates. 200 I take, say, from to 500 says :
some
of
amount
and
examination a
and
oxygen litre,and so
treatment, but
cyanide
solution
then
determine
calculate
kilogramme though oxygen
or
such more
shake
ton
out
of
the
for it up of known the amount
sands.
absorbed
I
some
material
in
a
or
lost
required by
however,
large
saturated
and
absorbed
of oxygen
would,
hours
quantity
amount
sorbed ab-
oxygen
of the
grams
has
Crosse
Mr.
"
with
was
liberated.
iodine
the
with
connection
full of
taining con-
freed from was cyanide solution oxygen 6*0 c.c. of hyposulphite required was 7*4 c.c. of hyposulphite required for the 6*0 leaves 1*85 in 288 of solution or c.c. by the free oxygen in 288 6*4 m'grams or c.c, oxygen per litre. of
amount
made
was
of
solution
the
saturate
remark
per each that
during by solved, also is as sulphides, etc., gold being disif no slowly and to a lesser degree than oxygen
is
being
ferrous
certain
substances
absorbing
matters
present, then
would
gold gold allowing some is being absorbed. that no gold would through the sands." no
almost
dissolved,
to
be
ZINC
OF
the
not
were
the
till several
AND
BASE
IN
oxygen
often
solutions
METALS
slowly,
that
it would
case
oxygen,
act
time
same
hydrate
the
up substances
certain at
dissolved
be
DETERMINATION
but
dissolved
If this
take
immediately
be
ferrous
have
we
43
SOLUTIONS.
OF
If
present.
were
would
which
ANALYSIS
AND
TESTING,
CONTROL,
happen passed
had
CYANIDE
A
SOLUTION.* Andrew
(By The
following zinc
iron,
Take
and
from
is
nickle
in solutions
500
1000
to
sulphuric acid, of sulphate potassium, and dish
and
The
metals
then
heat
obtained
are
estimated
in the
usual
the
solutions
than anything more is ingredient necessarily often
be
300
Take
of
grams in
dryness
to
order
in
and
sulphates
be
slight acid
pure
platinum
a
melt
to
can
a
the
mass.
separated
and
ZINC.
OF
Rand,
with
would
copper,
way.
the
on
six
or
redness
ESTIMATION
In
with
solution, acidify
five
evaporate
as
determining
—
add
dull
to
for
:
of
c.c.
of
excess
method
accurate
an
Crosse.)
F.
where
trace
a
and
zinc
copper,
the
usually
not
are
we
of
the
chief of
estimation
troubled metallic
this
metal
useful.
solution,
of
c.c.
add
about
a
gram caustic
of
cyanide of potash or soda, of slight excess be quickly precipitated
potassium and the same quantity of pure add then heat nearly to boiling point and a sodium will The of in zinc solution. sulphide be collected filter paper a a on as sulphide, and should with Then and washed hot water. place the filter paper in a wide and mouthed 300 bottle 250 of known c.c. capacity between This bottle be must provided with a well fitting india-rubber which is inserted about tube 8 a bung through moderately wide to 10 inches long. Then
fill up
the
sulphate containing bottle
or
flask
in
to
boiling point.
as
it allows
a
for the *Jour.
bottle 5
to
bowl The
a
7 per cent, of cold water
reason
expansion Chem.
with
and
for
the
of the Met.
weak of
solution
of
pure
ferric
sulphuric acid, place and
raise
glass tube
the will
liquid.
Soc., S.A., May
1902.
the
temperature be
apparent
44
CYANIDE
THB
PROCESS.
a decomposed and reduced portionate proof ferric sulphate to ferrous amount sulphate. When nearly cold, filter off the solution through a dry filter paper, and with bottle take half titrate and the in the quantity contained of potassium. decinormal permanganate
The
1
zinc
c.c.
"00325
=
weak
soluble
various
experiments,
per as
in
a
it
c.c.
the
to
Sulphide
zinc.
zinc
is, however,
having made that one milligram of zinc be the add to right amount
found
was
of
but
solutions,
cyanide
taken, would
of solution
correction
have
of
grams
slightly 100
will
sulphide
obtained.
results
quantities of prepared containing known the double cyanide of zinc and potassium with ferro-cyanide and were sulpho-cyanide of potassium, and the results obtained very satisfactory. Various
solutions
NOTES
ON
were
(By
cyanide
brought acid.
into
Most
small
of
with
becomes
air, owing
African
ALKALI
Crosse.)
F.
Andrew
potassium
contact
South
PROTECTIVE
SOLUTIONS.*
CYANIDE
IN
Pure
OF
ESTIMATION
THE
if
rapidly decomposed the
of presence slimes contain
to
tailings and
carbonic certain
a
sulphuric acid, or basic ferric salts, which We must decompose cyanide of potassium. protect or prevent this decomposition as far as possible. Cyanide of potassium is an therefore should endeavour to expensive material; we prevent its unnecessary of some decomposition, by the use inexpensive alkali
—
accurate
other
such
lime
as
method
for
protective
Protective
acid
of free
percentage
it
becomes the
determining
alkali
alkali
and
—
of
caustic
will
unite
amount
is the
alkali
pure the
or
which
present
with
any
before
alkali, but the results can caustic soda, if so desired. If
an
lime
in solution.
decomposition of the cyanide begins. It is very to be able to cases important in many alkali this of exactly. percentage In my lime experiments (calcium oxide) is taken
or
have
to
necessary
an
exact
cyanide following
calculated
sulphuric acid be potassium containing the
amount
of
be
reaction
of
+
added latter
the
tive protec-
for caustic
potash
to
solution
in excess,
or
98
pure
parts
we
of have
Chem.
and
Met.
Soc,
H2S04
liberate
bi-sulphate of potassium,
—
Trans.
a
—
=
*
as
:
K2S04 + 2HCN H2S04 54 parts of hydrocyanic acid. Now, if instead of H2S04 we take takes the following reaction place : 2KCN
out
the
determine
S.A.,
1899.
CONTROL,
KHS04 27
or
from
of
an
be
acid
grams
solution and
neutralized,
proportion
of
cyanide
potassium
alkali
such
to
less
that
protective alkali, I know of one KHS04 gram
no
KCN
of
excess
of
is
"1985 of
excess
an
direct
in
liberate
cyanide
sulphuric
liberated,
is
If there
present.
the
that
liberate
parts KHS04
will
containing
alkali, the
acid
hydrocyanic
136
or
45
SOLUTIONS.
OF
KHS04
gram
however,
free
a
one
HCN
+
solution
a
potassium. Supposing, contains
K2S04
=
HCN
parts
HCN
KCN
+
ANALYSIS
AND
TESTING,
in presence '1985 liberates
HCN.
grams If
less
retained
HCN
by
is liberated
the
alkali, so
2HCN 54
The
500
parts
for
now
nitrate
Let
A
Let
B
A-B
:
—
add
HCN
the
of KHS04, gram flask containing
one
in
through ordinary way
a
Liebig's Condenser. potash solution
a
vapour
in the
—
in the
of silver.
of
excess
=
amount
=
C
liberated
HCN
of
amount
=
of
presence
collect
the
HCN
the
follows
being
Oxide.
parts Calcium
as
its
to
H20.
+
cyanide solution,
a
potash, passing
I estimate with
Ca(CN2)
=
minutes, and
45
caustic
of
c.c.
practically amounts the equation
if I take
of HCN=56
proposition is
Take boil
CaO
+
it
that
without
cyanide found
C
x
1*037
or
one
alkali.
with
of
amount
«
in
KHS04
gram
alkali.
any
experiment
in
|£
by
calcium
oxide
present. I made
a
series
of
c.c.
various
proportions
cyanide solutions, and prepared results for instance, the following. I accurate as distilled of pure water cyanide containing two grams lime
very
with
experiments and
water
—
and
which
added
200
contains as
I had
0*260
described taken
c.c.
the
I obtained
liberated
by
HCN
liberated
in
2 grams
treating
results
KHS04
experiment
Cx
02461
=
oxide
Calcium
of
the
300
sium, potas-
Cent.) tion solu-
:
—
=
0*3970
=
0*1509
1-037
=
grams. „
•2461
C
took
KHS04.
2 grams
case
HCN
following
On
fully care-
obtained
18°
(at
water
oxide.
calcium
grams
in this
lime
saturated
of
of
0-2552
found
0-255
taken
0-260
grams.
grams. „
or
in
percentages
per cent, lime taken. a
from Of
„
„
„
0*051 the course
and
correct the
0-052
amount,
respectively or
within
operation requires
or
only 10100 of
2 per cent, of the and care practice.
46
THE
CYANIDE
GRAM Fob
the
Assay
TABLE. op
GRAIN Fob
the
Assay
PROCESS.
Cyanide
Solutions.
TABLE. op
Cyanide
Solutions.
CONTROL,
AND
TESTING,
TABLE
FOR
OZS.
8
Some
The
cubic
cubic of
ton
1
gallon
1
lb.
avd.
To
converts
lbs.
To
converts
lbs.
of
10
equals equals
into
avoirdupois
in
vat
feet =
feet. 62
=
contains
water
troy
circular
a
in
water
SOLUTION.
Constants.
depth
x
foot
1
of
content
*7854
x
1
Useful
OF
LB.
J
=
47
SOLUTIONS.
OF
ANALYSIS
J
lbs.
about
nearly. 36
cubic
feet.
lbs. 7000
grains.
lbs.
avoirdupois into
lbs.
troy
x
x
-82286. 1-2153.
Dia2
in
feet
CHAPTER
THE
APPLIANCES
V.
AND
PLANT
CYANIDE
FOE
EXTEACTION.
The
in
appliances
plants,
but
endless
the
of
the
zinc
by
affected
be
In
advantages
vat,
leaching and
gravitation,
as
as
all
his
at
disposal
should
be of
permit
to
shown
cases
the
individual
the
designer where
and,
;
the
in
should
possible, tanks,
three
on
circulation
following
taste
storage
placed
the
separate tions solu-
the
of
diagram
to
the
conditions,
vacuum-cylinder,
vats,
sumps
so
and
cyanide
subject
are
local
by
all
at
arrangement
treated,
metallurgist.
platforms,
or
chiefly to
nature
same
and
material
extractors,
tiers
the
shape,
being
natural
solution
much
of
are
size,
the
of
fancy
utilize the
their
variations,
character or
use
:
—
B
LEVEL.
FLOOR
Dissolving
A
Tank.
Solution
B
C
When it
below The
a
to
bottom
receive the
the
the
solution
sumps,
tank is either
Sump.
E
Extraotob.
—
is
storage
arrangement from
D
Vat.
Leaching
vacuum-cylinder
of
Whatever
pumped
—
Tank.
—
—
—
used,
a
when
adopted, to 48
the be
must
the
tank
storage
cylinder above
the
solution
the
placed
becomes
full.
extractor.
solution tank
be
must
has
B,
or
to
be
directly
50
THE
12.
and
of weak
Lines
with
vats
CYANIDE
PROCESS.
strong solution
pipes connecting leaching
extractors.
washing and drying gold precipitates. 1 4. Melting and roasting furnace. 15. Assay office and laboratory. In the intermediate of double ditional or case treatment, filling,advats are required. They are generally placed over, or at the leaching vats. than higher elevation Filter
13.
a
for
vat
Tank.
Dissolving and
made
When
steel. when
of iron
2|
from
of
varies
4 ft. in
ft. to
the
wood,
size of the
size
is constructed
steel, the
or
the
according to hoops. The
This
—
staves
from
3
of
are
J
stiffened ft.
6
to
wood,
2 in.
from
plates are
vat, and
of
iron,
or
2| pine ; in. thick, £ in.
or
in. to
with
angle-iron
and
ft. in
diameter,
and
depth. works
a perforated tray, to hold the solid large cyanide the tank steel-wire cyanide salt, is suspended over by a chain or The end overhead. a pulley fixed to a beam running over rope, chain of the second the a over or pulley on same rope passes distance to permit a balance-weight on beam, fixed at a sufficient
In
to clear the side rope practice the solid salt is taken
end
the In
of the
of the
tank. of
out
the
original packing
cleaned, by removing adhering particlesof sawdust with other It is then husk-broom. broken a or packing material small is into placed in the perforated tray, which pieces and into the solution. The allowed to subside rapid dissolution of the be effected salt the to cyanide can by imparting motion tray by end the the of at weighted pulling rope. should the The from always be discharge-hole dissolving tank the above a bottom, so as to allow placed three or four inches in the cyanide. settlingspace for the impurities contained contained commercial in The cyanide consist pally princiimpurities and
case
all
carbide
of black
filter of
webs,
and
in the
its presence a
portion
the
solutions
to
from
ft.
14
depth.
dowelled
placed
to
They
sides The
the
are
would
are
made
used
are
ft.
in
diameter,
3
ft.
for
They and
cause
of a
constructed
of 5 in.
6 in.
or
of
apart,
and
making are
open
from
generally
gold ; hence loss by tating precipi-
of
4
the
cyanide
circular
tanks
up
ft. to
14
ft.
well-seasoned
are
in
pine.
3 in. thick.
planks, 2J in. or planks 12 in. by 3 in., bolted
together independently about
to
the up this,carbide
gold. These
is constructed
bottom
tend
choke
Besides
solution
cyanide
potassium
which
matters,
pipes,
delays.
working strength. 20
insoluble
solution
the
solutions
—
other
vexatious
cause
of the
Vats.
Solution
The
thus
decomposes
iron
iron, and
permitted, obstruct
if
would,
of
of made
the
sides. of
£
in.
bolts
The or
and
1
in.
are
round
THE
The
iron. and
APPLIANCES
AND
and
washer
PLANT
nut
CYANIDE
FOR
well
are
51
EXTRACTION.
countersunk
the
into
plank,
being tightened, the whole is plugged up with a block the bolt. The dowels consist to prevent leakage around of and round 6 8 in. in. in. are iron, or long. They are placed | about 12 in. apart where the planks come the circumference. near The bottom is rebated into the side planks, which are kept tight iron hoops, f in. to 1^ in. in diameter, having three by round or each cast-iron turn-buckles sometimes on One, and more hoop. india-rubber of round round in. the are two, rings placed J bottom before the rubber The staves are rings are put on. with steel in which made tool. are a placed grooves side The kept in their places by the planks, or staves, are of the hoops alone, which 15 are generally placed from pressure The extra in. to 18 in. apart, with an hoop at the bottom. hoops six inches or seven are placed, on very large deep tanks, only after
of wood
apart
the
at
bottom,
the
where
apart gradually increasing is
hoop
extra
buckles
will
One
or
size of the
square these
close
as
solution
more
vats
the
to
20
or
in.
bottom
the
the
at
hoop
distance The
top. the
as
turn-
may
be
required according
to
the
plant.
tanks
tight
wood
of led
Vats.
Percolating
or
shapes, sizes, and to
the
were
the
Africa
Zealand,
New
of
used,
but
favourite steel
of
These
—
kinds
adoption
stronger. In Australia, and
in.
greatest,
permit.
Leaching different
placed
18
to
is
pressure
material. the
circular
material
is
made
are
At
of
difficultyof
keeping
vats, which
wood,
many
first, small
but
are
in
also
South
preferred to wooden all the in recently erected cyanide plants. In ones, America, both steel and iron vats are preferred to wooden ones. In Victoria and New South made of Wales, leaching vats wooden with bottoms have been iron used ordinary corrugated Mr. used with who them W. Eddowes, satisfactoryresults. very author that in Victoria, informed the they were light, strong, of large capacity, corrugated iron For vats cheap and durable. of No. that The is said to be half is employed. 16 gauge cost of "When value steel vats the of of the same corrugated capacity. iron becomes better will be doubtless it known, more largely where in port transoutlying mining camps especially employed, more costs are heavy. wooden The of the circular construction leaching vats is in solution the that of vats as same already respect the every with in described, differingonly discharge-doors. being provided The
first
and
Silver
vats
in
use
at
Mining Company
the
vats
cyanide 22 J were
are
at
present
works
of
ft. in
diameter,
the
Waihi and
Gold 4 .ft.
52
THte
bound
f
sides
The
deep. in
in.
each
Five
ten
are
inches
4 ft.
the
by
for
consisted
Thames, the
off
in two
three
in.
3
planks,
iron,
thick,
of which
were
turu-buckles
three
on
false
depth by the new Company's tank each being
the
At
cloth.
the
rows,
of wooden
supports
or
author
kauri
in., having taken
tanks
7 ft. staves, to hold
with
in.
5
mill, 50
ft.
deep.
foundations
The
is
PROCESS.
of round
1
two
concrete
ft. and
40
by
and
of
hoops
filter-frame, and
bottom, there
five
diameter,
hoop.
built
were
with
together
CYANIDE
the
of
of 70
charge
a
vats, 20
15
mudsills,
in.
6
by
diameter,
tailings,designed Mining Company,
of
tons
Gold
Moanataiari
ft. in
in., laid
which
flat, on
or pieces, 10 in. by 8 in., supporting the props laid the bearers of the same uprights, 8 in. by 8 in.,on which are the sole pieces. There five rows of dimensions two as are props of three, three rows of five rows altogether, twenty-one in number with ft. The the 4 bottom of centres vat rests both spaced ways.
rest
sole
—
—
the
on
which
bearers, their
between detect
and
of the
vat.
ends
and
solid rock
the
dispensed with.
be
The
advisable
place
to
evenly
more
rests
the
on
At
the
tanks
diameter,
and
At
ft. inside
26
iron
see
steel
or
planks across weight of the vat,
the
mudsills
can
I.) it is
vats, but
bearers,
the
sides
the
Plate
to
bottom
so
of
to
as
which
constructed
are
14
Cyanide
Jack
ft.
deep
;
of
bound
Johannesburg, the 42 ft. in pine. They are fifteen together with hoops Works,
The staves piers of solid masonry. made of 9 in. by 3 in. material. are Main Reef Works there six leaching vats, each are and with 8 ft. diameter, staves, holding 135 tons of
They
rest
on
"
"
the
drawings, for
the
upon,
wide
in.
is left
space round
place
3 in.
by the
and
iron.
bottoms
used
4
space
planks.
leaching
and
9 in.
take
to build
a
This
planks. may
detailed be
can
distribute
Simmer
of round
that
exposed
is
(For
support
same
side
allow
to
as
so
the
leaks
repair any
Where
cut
are
tailings. The
staves
wide
in.
by machines, and edges. They are checked
level
the
6 in. below
chime The
by
4£
are
on
grooves.
apart
by
3
from
These
the
afterwards
f
in. to
3
in. thick, and hand-dressed
fit
the
on
on
planed the
bottom,
to
ting abutwith
a
check. is made
of 9 in.
3
in.
deals, planed grooved f in. by \ in. by a saw, and is also handthe edges. Clear-pine tongues, 1 in. by f in., fill the The the the tunnel, below joistsacross vat, consist of and in. deals, bolted in laid 2 ft. 3 in. together pairs, vat
by
and
machine
9 in.
of
bottom
dressed
the
and
centre
joistsare
to
centre.
first laid
in
position,then
the
bottom
of the
vat
I I
I
PLATE
I
1
NN
'
».
is laid is
cramped
down,
now
for the Six
places ; the lowest Each
1 in.
top pair
connected
circle
when
three
in
The
out.
all
round
bottom is
ready
to
with
ends.
screwed
sections,
rolled
required
the
to
turn-buckles.
cast-iron
by
struck
bevelled
up as used
diameter,
in
53
EXTRACTION.
tightly as possible. in their are keep the staves in diameter, the middle pair 1^ in.,and
iron
pair If in. hoop is made
and
curve,
round
of
hoops
the
driven
are
CYANIDE
FOR
and
up,
which
staves,
PLANT
circle, and
the
to
sawn
the
AND
APPLIANCES
THE
Q Fig.
1.
Showing
—
Construction Scale
The each
screwed is
hoop
Two for
ends
being
drawn
carpenters, practised it in about
erect
four
while turn-buckles, and with hammered a sledgeheavy hammer.
it is
up
the
work,
the
at
and
ft.
=1
through
pass
vat, 28 ft. in diameter
a
£ in.
:
Turn-buckle.
of
8
in
deep,
ft.
dress
can
material
the
about
a
and
week,
days.
and of brick vation excacement, in an large vats, constructed the what age leakthere of in is no means ground, ascertaining is going on; in which and, in a process gold solutions are of the leak, in the course being dealt with, an exceedingly small With
would
year,
represent
construction for
the
tanks
Langlaagte round
are
Reef
10
deep.
ft.
constructed
7
At
the
jV
in.
At
deep.
Works,
Colorado,
in
where
material
and
ft. in diameter also
16
steel, being the
Cripple the
vats
steel
of
10
ft.
brick,
Works, vats
20
are
Gold
made
are
is
procurable S.A.,
the
with
40
N.Z.,
hydraulic deep. At the
ft. square the tanks and
ft. in diameter
Creek
their
reason
Works,
Cyanide
brick, faced
of
are
this
vats.
Waihi-Silverton
mine, the
For
Company's
tanks
the
Moanataiari
the ft.
of
is 40
loss.
steel
or
constructed
size
Works
Crown
Estate
and
Their
cement.
At
of wooden
construction
the
At
recommended
be
cannot
considerable
a
4 ft.
ft. in diameter
and are
deep. and
Exploration Company's iron, being 20 ft. in
of
diameter. For are
seldom with
free
direct
the
from
of
deep, on greater depth of ore
over a
treatment
slimes
4 ft.
the
depth
dry-crushed account ;
varies
of the
the
leaching vats difficultyof percolation tailingscomparatively
ore,
but,
with
from
8 ft. to
14
ft.
54
CYANIDE
THE
The
leaching vats, built
be
must
and
the
they
built
often
are
Australia,
where
Whatever
the
the
bottom
firm
be
sure
of
stone
the
to
; and
tanks,
so
In
able
South
New
in
be
and
wood.
of
free
detect
to
Africa
Zealand
frames
always
be
to
as
to
as
massive
should
foundations, there
so
weight they hold, prevent settling,
follow.
piers is plentiful,on
on
timber
of
enormous
foundations,
would
which
leakage
of the
account
on
strong
on
PROCESS.
to
access
and
repair
leaks.
provided with a separate drain-pipe,1 J in. or 2 in. each in diameter, with two the stop-cocks near other, one over the weak solution or pipe, the other over strong solution launder tion filtraWhen launder, leading to their respective zinc extractors. is assisted by a vacuum, a third stop-cock is provided for the air-pipe. with The sizes of the pipes for charging the the solutions vats tank
Each
are
as
is
follows
:
—
Vats, 20
ft. in diameter,
24
—
24—32
ft. „
„
32
40
—
for
one
medium
lines
of
with
pipe
and
in.
3
in.
4
in.
...
„
three
or
2£
...
ft.
„
Two
.
.
mains,
two
three
with
the
for
one
the
strong;
for
the
and
running parallelwith strong respectively)
the
mains,
one
economical, and leaching vats, afford the simplest, most solutions of collectingthe method as they percolate from This
enables
system and
the
readily,and
solutions
by
this
each
from
means
vat
to
mishaps
any
and
weak
weak, line
of
effective the
be
tested
can
at
vats.
separately be once
detected.
having stop-cocks on the end of the drain-pipe,from each is sometimes the fixed on vat, a short length of rubber-hose be drained into the end ; and by moving the hose the solution can launder weak required. as strong or iron Steel and vats are now They coming into general use. wooden ones. advantages over They are generally possess many of coal-tar, coated with a composition consisting of a mixture (See Plate II.) pitch, and kauri gum. is supported on The in steel filter-frame vats a ring of iron Instead
riveted
of
to
the
side
about
3
in.
from
the
bottom.
The
filter
and kept in its place by means of a webbing is laid on the frame in four, six or eight pieces, ring of angle-iron,which is constructed The of lengths, so as to be easily handled. ordinary method or the ring of iron and the side of the grouting the cloth between with
vat
In is
a
large
small
rope
steel
vats, the
omitted, and
in this
is the
case
best.
ring the
for
the
reception
filter-frame
of
the
is constructed
filter-cloth so
as
to
m
I V V
THE
APPLIANCES
leave
AND
FOR
PLANT
CYANIDE
annular
an
the
permit
wide inch an space filter-cloth be grouted to
round
all
55
EXTRACTION.
the
between
the
vat
so
as
and
frame
to
the
vat.
Filter-Frames.
The
—
old
filter-beds
of
gravel and
sand
been
have
frames, over entirely superseded by light wooden are filter-cloths of either extra placed webs, consisting or strong For the tion filtraHessian, loose canvas, cocoa-matting, or burlap. of slimes, or dry-crushed ores, which a always contain large fine sands, a webbing of strong Hessian or percentage of very is and for tailings or of concentrates used; canvas a webbing cocoa-matting or burlap. In some filter is laid over plants a duck-cloth cocoa-matting. The about duck-cloth for a 100 ton vat costs £2, 10s. ready made. At the Waihi the filter-frames,designed by the Cyanide Works of narrow Mr. H. P. Barry, consist laths placed general manager, which
and parallel,
about
inch
an
On
apart.
these
transversely, narrow
moulding-like laths,
An
or
an
frame-
open inch square. At the Main
ends
their
wood,
a
less
inch
for
support
in
annular
passing
finds
author that
than
has
the
of
top
the
the used
in
the
its
the
slats
1
apart.
in.
apart
place by
about
an
leaves
permits of
means
an
the
small
a
vat.
for
advantages
sections.
frame
vat, which
filter-frames
many
in
This
vat.
of the
circumference such
possess
and
frame
the
of
that
firmly grouted
round
they
on
cocoa-matting. constructed for large vats are circular fitted together, form a
between
The
an
obtained, having openings
is thus
the
diameter
space filter-cloth to be
rope
nailed
are
sections, when
The
inch
3 in.
filter-frames
The
nailed,
are
Reef
of
1 in. square,
form
to
grating
about
also
the filter Cyanide Works, Johannesburg, 6 1 in. in. slats,placed on edge, by apart, the from of the 1 in. sides vat. being kept Strips of
is made
frame
work
laths
over
over
five
years,
old
the
and
gravel-
filters. At vats
plants where provided are
automatic
Vacuum-Cylinder assisted
fillingis adopted,
intermediate with
and
the
intermediate
distributors.
Air-Pump.
artificial
—
Filtration below
is the
generally filter-bed.
by creating and Australia Zealand to promostly adopted in New duce with is an a vacuum air-tightboiler, or cylinder, connected and In air-pumps an large cyanide plants two air-pump. cylinders and storage tanks should be provided. of The £ in. boiler-plate, generally constructed cylinders are of different made with sizes, according to They are f in. ends. and 3 ft. 6 in. from requirements, from 6 ft. to 13 ft. in length, to 6 ft. in diameter. They are provided with a solution-gauge, The
means
an
vacuum
56
air-cock, and
vacuum-gauge,
PROCESS.
CYANIDE
THE
man-hole,
well
as
the
as
necessary
connections.
pipe
single or double-acting, 7 in. in diameter, with 80 to 120 strokes 8 in. stroke, making from an per minute, and the in of in. of 26 capable of producing a vacuum mercury be it should rounded surcylinder. To prevent heating of the valves with of cold current a water-jacket, through which a The the is running. water continually circulate when can pump cyanide plant is 14 in. in diameter, and air-pump at the Waihi The
has
a
air-pump
in. stroke.
22 the
All
is
and
stop-cocks, valves, pipes
and cylinder, air, and solution pumps, be of black cyanide solutions, should When the vacuum-cylinder becomes
about
connections
tanks,
which
the
subject
are
to
iron.
charged full, the solution is diswhich it slowly drains into a storage vat, from through the In when order the zinc to extractor. give timely warning full, the following simple electrical contrivance cylinder became Gold used Cassel at the Wilson, the manager, was by Mr. Arthur Extracting Company's tailingsplant at Waihi. Erdmann A small float,with a platinum wire fused into the top and coiled into a flat helix, was placed in the solution gauge-tube. the wires also into fused end of the Two were platinum upper tube, opposite to each other, but gauge- tube, projecting into the The small with connected in contact. not platinum wires were a the float rose in the Leclanche battery, and when solution-gauge metallic contact to the platinum wires, was established, and an bell
electric
in the
of
Discharge method
sounded
water,
an
alarm.
Residues.—
Leached
of
plentiful supply
with
a
good
Where
head,
there
is
easiest
the
a
and
the discharging the residues from leaching side-door. At the is to sluice out cyanide plant by a the residues Gold Waihi sluiced out Mining Company are head 150 of 2 in. hose-pipes under a ft.,giving a pressure
cheapest
of
them
tanks of the
by
circuit
two
of 65
lbs. to
the
square
inch.
there is a scarcity of Goldfields,where of fall for the bottom charge dissludge, the water, and often a want the residues shovelled is largely practised, being through the truck hole in the of into bottom vat a a immediately below. the tailings are At the Barret shovelled into a Company's Works At
the
Witwatersrand
"
"
launder At New the
below
the
vat, and
Woodstock Crown, the ore Zealand, where
stream
a
and
the
residues
contains
sluiced
of water Talisman a
carries
them
Cyanide
percentage
of
away.
Works
coarse
in
gold,
over slowly amalgamated copper below the discharge holes. plates placed immediately At the Langlaagte Company's Cyanide Works, near Johannesare
extensive
PLANT
AND
APPLIANCES
THE
FOR
57
EXTRACTION.
CYANIDE
the discharged from large brick leaching lower the bodies of steam tanks travellingcranes, which by means trucks into the tanks, where of the empty they are filled by Kaffir trucks and filled raised the labour. When are placed on their to the dump. carriages,to be wheeled away When Doors. side-dischargeby sluicing is used, Discharge outlets are two or generally provided for each vat ; but in the one charge of bottom-discharge there are two, four, six, or eight discase openings to each vat, according to its size.
burg,
residues
the
are
—
Fig.
At
2.
Butters'
—
the
Bottom-Discharge
Witwatersrand
Scale
Door
Goldfields
J in.
:
=1
ft.
bottom-discharge is When wooden employed leaching vats. discharging the round fillinga deep tank with tailings,a length of wrought-iron pipe or each cylinder, three or four feet long, is placed over dischargeThe in. hole, and then the tailings are dumped pipe raises the the
for
outlet
within
a
few
feet
of
the
surface,
and
facilitates
thus
the
discharge. On
these
used.
Fig.
The
side
of
fields, Butters' 2 shows
arrangement the tank,
their
simple and cast-iron ring, A,
is very a
bottom-discharge
doors
are
largely
construction.
effective. is bolted
On to
the the
bottom
cast-iron
58
CYANIDE
THE
cylinder, B, inside
lug, C,
upon
screw,
E.
fastened whole and
The
3
Fig. of
out
made
would
but
The
be
a
the
the
ring
good
a
designed
door, and
construction
Mr.
by
likely
not
shallow
in
convenient
more
is
firmly of
make
to
the
luting of clay.
-discharge
in
this
as
of
position,
in
faces
so
even,
projecting
a
part
placed
by screwing
tight by
bottom
is
forms
which
watertight.
It is simple
order,
G, and
planed perfectly
another
cylinder
when
F,
cover,
is also
joint
shows
Irvine.
F.
hanger,
D,
becomes be
should
joint.
the
butterfly-nut,
arrangement The
the
rests
cast-iron
the
by
cover
W.
which
Inside
tank.
the
PROCESS.
to
than
get
deep
vats.
Plate
II*.
handle.
to
in
It
Fig.
3.
A
Irvine's
—
construction,
originally designed
was
Recesa
for
R.
G.
Walker,
Door.
S"ale
Packing.
efficient, and
Mr.
by
improved
an
very
Bottom-Discharge
—
of
drawing
working
door, simple
bottom-discharge easy
the
represents
in.
J
:
=
4 in.
'
improved
Mr.
by
by the
form The
the
above
applied by The
in
patent
a
door
is
at
an
the
the
iron
both and
button
door,
is then
left
is
inserted
in
serves
tightening.
The to
the
the
side
instead
loose
keep
the
the
discharge hand
right lugs
and
iron-button
the
door
and
the turns
in
so
as
in
door
position
with
and
a
then
door
is
position.
wide the
ring door
turning weight
the
carry
loose
The
of
dog with
screwed on
differs
the
swinging
hole,
easily
works.
centre.
faced
to
present
market
close
to
the
its
cyanide the
in
by lifting, or
approximately
now
placed of at
in
used
other
pressure
hinge,
the
over
with
which
hands.
that
It is closed
hand
and
recently
in
a
and
perfected
Moanataiari door
on
swung
of rubber-insertion. with
the
tank
only
screw
and
Price,
author
Koppel
from
A.
a
tightly up small stud-bolt,
preparatory
to
the
final
?5.'
60
CYANIDE
THE
The
lug the
on
the
on
side is
right
left with
notch
the
PROCESS.
placed with
in the
the
notch
that
upwards,
position.
reverse
The
is kept in door, which opening is closed by a cast-iron the of a position by screw acting through a loose iron pressure the of which fit into the dog, the ends lugs so as to obtain leverage. necessary The of the door is suspended in front opening, preparatory to round of bent is supported on iron, which fixing up, by a hook the projecting bar on It the frame. is rendered watertight by a of fixed rubber with insertion, facing on tar, or by a luting of clay. These doors seldom give any trouble. They are easily opened closed by a few of the The different turns or screw. parts are shown
scale
to
Steel
III.
Plate
on
for
Sumps.
There
—
bottom-discharge, designed by Plate Cyanide Plant, are shown on
Moanataiari
the
the
with
leaching tanks
author
least
at
are
these
of
two
in
II.
cyanide
every
plant, cyanide passing through the for the weak. zinc-extractor,one for the strong solution and one In acid is often ores an plants dealing with or tailings there washadditional tank these for besides storing the alkaline the
receive
to
solutions
after
solutions. The In
constructed wood.
In lower
plants decked
they cleaning. are
of
The
leaching
bricks
faced
material.
The
of the
depth
solution
the
of
with
cement,
construction vats.
or
level
the
such
in
the
of
for
cases
repairs by the
indicated
is
plant. They
vats.
tanks
storage below
are
of the
size
placed cyanide building, and planks, having a man-hole
with
over
or
as
sumps of the
floor
that
the
on
the
as
favourite
same
the
size
steel,concrete,
is the
is the
extractor
or
are
latter
sumps
many
sumps the same
either
The
of wooden
depends
storage
plants they
most
are or
size of the
tell-tale. In
strong solution
in
up
storage be
with
so
as
such
pulp
dry
requiring advantage for
it is necessary
below, the
from
ore
Zinc
to as
for
one
works
treating
consist
formation
occur
the
were
of
could
a
not
in dry-crushed ores slowly from strong solution in channels of lumps and of
treatment
the
method
This
sump.
construction
turned
solution
the
sands
—
There
strong and
at
are
solutions slimes the
least and
of
two
the
to
on
one
it is usual
for to
these
the
in weak.
provide
medium
for namely strong, of constructed are respectively. They number into a oblong boxes, each divided
extractors,
of
the
prevent
Extractors.
solutions
the
apply
to
would
extra
an
is made
solution
above.
plant, three
working cyanide thus saving the
sumps,
vat, but
used
which
the
tailingsplants
some
a
and
wood,
every In of
set
weak
and
of compart-
loose
N
Dog
I
tr,
o o
1
Q id V
Q •I
D "
CO
!o
o
i
^
1 o
O
]! o
o
o
V|
I
MMu\A
YtlW
«!--
,j"iiyi"
^i
in
i
i
i
,
*
v?r
i
'
./
r
:.} i^"
^ ^
5 i
»• i
I
\*i n
§ ro
"•?"
V "i
I
Mi
! .-
U
V..-, .••
.' S
i»^*.
**,,*»
*
*
**
*fn*-'
"
*•*«**
t**"
-vrt**
»
*?*
1
i
'I
'
1.
T#E
APPLIANCES
AND
PLANT
generally eight, ten,
ments,
baffle-boards
upwards The
fixed
in such the
through
as
The shallow round
The
enable
the
permits and
gold
zinc
of the
bottom Instead
are
with
be
slimes,
they
as
tow
to
the
in
matter
removable
often
when
up
screen
of
of the
solutions,
and
form,
to
circulation
free
wire
a
way
of slimes.
handles,
easily lifted
bottom,
its
or
provided with
convenient
to
the
at
escape
sometimes
sand
clayey
any the
finds
compartment.
filled with
remove
partitions and
of
solution
each
61
EXTRACTION.
means
the
are
prevent
them
trays support,
which
to
wood,
of
trays iron, to
to
one
divisions
remaining
that
way
compartments
filters,the upper solutions, the lower one
act
a
twelve, by
zinc-turnings in
last
first and
or
CYANIDE
FOR
fall
of
bent
necessary.
£
mesh,
in.
enables into
through
the the
compartment.
projecting handles, the trays are often provided with iron plate on sides with holes in it to take two the two an end 8 of hooks their contained for liftingthe trays and zinc. The extractors are cleaned-up from plug-holes on the side, one the bottoms To facilitate the to each clean-up compartment. of the compartments sideslope to the side, and also to the lower where the discharge-hole is situated. corner, launder of wood the A iron is fixed or on discharge-side, under the receive the slimes when to immediately plug-holes,so as boxes. The out of the they are washed top of the extractor, as well as lid or the side launder, is protected with a close-fitting tents grating of wood or iron, provided with locks, to prevent the conof the extractor being tampered with. wooden To facilitate the of the the withdrawal plugs from fixed in the holes. are discharge-holes,short lengths of rubber-hose The rubber is yielding, and, while rendering the holes water-tight, the enables without which the force is plugs to be withdrawn when generally necessary they are driven into the bar-holes. The should constructed be of well-seasoned extractor pine, with of
"
"
sides of 1 J in. well
dressed. and
plant,
3 ft. in
depth,
It is
place
now
in the
to
of
six
extractor
into
or
late
are
shown
of
reduce
simply
compartments, "
or
volumes
eight, and is
that
to
without
periodical clean-up
"
each
bulk
box
1
in. boards,
of
their or
side
The
the
precipitation takes in cyanide plants handling daily, the tendency has
divisions
trough plugs or
divided
side
the
in
dimensions.
compartment
extractors
IYa. of
solution
number
increase
long
a
in. in width. and
boxes, and
cyanide the
of
the capacity of the upon 20 ft. in length, from 2 ft. to
IV.
the
three
divisions
depend
Plates
on
known
first two
to
will
size
the
from ft. to 12 vary 15 in. to 45 and from
well
large been
The
will
used
mostly
in. boards, and
2
or
this
by
baffle-boards
launder.
is cleaned
extractor
In
case
At
the
the
separately ;
or
62
CYANIDE
THE
sometimes
two
or
communicate so
the
thus
set
or
that
run
often
all the
each
other
by plugs
the
slimes
construction
of the
design according bearing in mind
to
solutions
upward
to
the
pass
Plate
the
at
IVa.) permits fancy of
extractor
the
object through
the
zinc
a
variety of engineer, always is to compel the
the
at
tub
endless
an
attained
be
to
of
one
into
out
to
baffle-
of
lower
the
baled
be
made
are
bottom
into
thence
and
individual
that
compartments,
washed
be
can
communicating, a bucket. (See
into
The
more,
with
boards
PROCESS.
and
uniform
a
slow
rate. the
At
Waihi
Company's large mill at Waikino, the solutions collected in a rectangular tank divided into three compartments are each coir-filter forming a or clarifying box, for the strong, and weak medium solutions respectively. Each is provided with false-bottom, 9 ins. a compartment with is kept in place by a cocoanut deep, covered matting which frame. light wooden From the clarifyingboxes the solutions or run compartments, into the different made 23 extractor ft. long by boxes, which are wide 3 ft. have flat bottoms by 2 ft. 6 ins. deep. The extractors into nine and are divided for precipinamely seven tation compartments, and for settling,one filled with which two each is at end, tow.
The The
trays
slimes
holes
to
as
so
The
leading
a
into
the
end
each the
over
other
a
is
with
drainage
The
from
small
this
—
the
extractors
to
In
Australia
and
of A
a
is constructed
floor
shallow
a
to
well.
small
Zealand
New
cast-iron
funnel-shaped
furnace
with
pipe connecting
cement
consists
over
in.
The
furnace. the
3
a
or
pan
hood
off* the
carry
is
suspended by
upper
and or
a
chain
is balanced end
narrow
the
the
steel-wire
or
of zinc
to
rope the
light oxide
passing
end weight on of the hood telescopes for condensing flue, and by means
by
a
pipe leading lowered the balance be weight the hood can roasting pan or plate as required. The first part of the condensing flue is of cold stream a length of iron-pipe,on which the mercury allowed to play, so as to condense into
screens.
through plugged
compartment
by
Furnace.
placed
pulley overhead,
feet
mesh
in.
£
fumes.
hood
chain.
box
sumps.
cyanide plants
wrought-iron The
to
all
convey
plate, built and
covered
leave
Roasting
in small
and
boards.
baffle
solutions
main
deep
washed
are
in the
The the
6 in.
are
raised
or
a
nearly water
over
the
of
few
a
of the
over
horizontal
is sometimes
vapours
and
zinc
fumes. In
large cyanide works,
a
built-in
muffle-like
roasting
furnace
Plate
IV
64
CYANIDE
THE
Kalgoorlie, and seems and sand-pumps tailingswheels So
air-lift
the
far
seem
erection,
not
continuous
a
several
it possesses
recommend
to
both
Australia.
in Western shown
supersede
to
high efficiency for the specialadvantages which it to mine namely : cheapness of owners, and operation, and little wear tear, having
; but
employed
power
has
time
likely in
in
favour
PKOCESS.
The Associated Mine complicated parts to get out of order. has in operation ; Kalgoorlie, six ; Boulder two No. 1, four Westralia View Mount Consols, one ; besides Morgans, two ; Lake
no
others.
many
deserving append the
which of
I
indebted
am
attended
has
the
the
to
lifts air-
form
of
elevator
for
that
reason
construction,
Max
Mr.
of
courtesy
of
use
for
Bernewitz
von
Kalgoorlie. He
a
which
success
Australia, it is certain that this of more general application, and following lucid description of their
in Western
I
the
from
Judging is
;
height the
on
:
the
the
has
pulp
be
be
start
the
up,
The
always in it a column lifted,whereby the to
of lifts to
put
sunk.
lifted.
be
to
number
size and
6 in. lift is to should
erecting an air-lift the same depth, or better
In
"
says well-hole
a
why
reason
of
be
erected
with
air meets
hole
is that
is sunk
lift has
the
height
to
be
to
required
resistance
necessary
the
3 ft. in diameter
pulp, equal
the
than
depends example, if one
for
:
sinking
of
more
the
of
less than
hole
and
water
size
not a
ft.
still,2
The
well-hole
is that
first work
in motion.
column
large pipe, say 2 ft. 6 in. in diameter, with a tapered into the of the same depth as. the well-hole, is lowered The fitted latter. delivery pipe or lift is then together for the into the large pipe. correct Finally, the airlength, and lowered down side of the the at lift-pipe. pipe is fitted together and run the At the bottom looks into of the air-pipe is a bend which up all the lift about 2 ins. It is desirable to have flanged joints on order in that be pipes, they may quickly and easily disconnected "
Next,
bottom
in
case "
At
a
and
of
accident.
an
the
top of the
practice now of the pipe.
a lift-pipe,
is to bolt this
By
launder
a
bend
directly on the
means
air,
as
fitted
be
may
to
a
on,
flange at
it reaches
the
but
the
the
top
top,
can
once."
at escape It has also
the
better
duplicate If
loss
in
the
pressure, a lift,and a
is
that
efficiencyattained case
air a
found
been
is
of
;
larger
also,
that
and
air-
the
lift-pipes,
should
air-lifts
be
in
mishap.
taken
from
several
pressure
expanded
of power.
the
But
before if the
a
receiver
times
greater than doing its work, it air is taken
direct
five
atmospheres actually required by
at, say,
is found from
the
that
there
compressor
is
1
-18
—18—
« .
i
I
I
APPLIANCES
THE
AND
PLANT
65
EXTRACTION.
CYANIDE
FOR
to the
is obtained, as the rising and air-lift, a far greater efficiency of the level of the pulp acts the to falling as a perfect governor The of is air most the take to mines practice on compressor. from it to a receiver At, say, five atmospheres pressure, and conduct this is unsatisfactory,and a lift through a reducing valve a ; but separate compressor giving large quantities of air at a low pressure is the
economical
more
Again, when working of the mill
the
method.
supplies air for compressor lift is greatly interfered with. a
purposes
many
the
example, running at a
Take,
for
the
Here a Kalgoorlie Mine. compressor air to actuate solution two high speed supplies ; also air to pumps agitate slimes ; to force the agitated slimes into filter-presses ; to three lifts pulp of which air-lifts, one dry the presses and work 20 sands 30 clear feet, one feet, and one water, 15 feet high. at
the
All
with
above
the
air
require
working
the
of
for the
at
different
air-lifts. would
lifts alone
It
and
pressures, is
that
certain
interfere a
small
be
more satisfactory. costs are fuel, water, and wage goldfields,where high, the working of air-lifts is fairly expensive, but in countries where be driven can by water-power with little or compressors attendance, the cost should not be high. no Tn the Kalgoorlie Mill a little trouble was experienced with a 20 with elevates red hot roasted ft. lift,which ore previously mixed diem lift elevates salt water. This of dense 700 tons pulp per with The raised air of 0*7 an atmosphere. pulp when pressure hard is almost at boiling point, and a deposit quickly sets around the This them the bottom. at pipes, and gradually chokes up the is due the of lime from to and magnesia ore. deposition In this mill a proportion of six parts of water to one part of ore meter, 8 found The above in. in diawas lift-pipewas necessary. and air-pipe 1£ in.
compressor On the
In
W.
the
Hainault
months
with
hung
for
up the
At in
At
A.
no
Mill,
stoppages, whereas
latter mill
stamps, crushing
Height Depth Total
of
for
over
sand-pump
was
twelve
always
Morgan's mills, lifts are settlers the to slimes from agitators. of 30 head raises pulp from lift which
there
120
Mount
Westralia
and
is
tons
a
diem.
per
Its
dimensions
above lift-pipe
well, about
20
below
top of well
22
„
„
length
Diameter
the
worked
repairs.
Associated
operation elevating thick the
ft. lift has
25
a
of
are
:
—
feet. „
42
lift-pipe
„
6 inches.
of ,,
air-pipe Air-pressure „
....
.
.
0*8
atmosphere. 5
66
CYANIDE
THE
/At
Kalgoorlie, the
bottom
from
sumps.
lifting
mercury
from solutions for
are
the
having
air-lifts
are
the
to
At in
following
PROCESS.
employed to circulate cyanide and of to leaching vats, top Boulder
the
No.
connection
dimensions
:
the
and of
capable
condition
air-lifts
two
Reicken
raise
process,
—
intended
the
capacity per material treated. A be to plant of freely-percolatingtailings per
of the
2000
treating
would
Mill,
the
with
Air-pressure, 3 to 5 atmospheres. size of the plant will depend on The month
1
tion solu-
tons
able half that than to treat more probably quantity of dry-crushed ore or slimy tailings. With exceeds dry-crushed ores the depth of the charge seldom 4 ft.,while with reaches 10 ft. sharp tailingsthe depth sometimes 12 ft. of dry-crushed ore or are Cyanide plants for the treatment therefore with of shallow those vats a provided large number ; and for tailingswith number smaller of vats. a deep number of The the following gives leaching vats required for the of different and treatment quantities of dry-crushed ore tailings. month
For
Dry
4 ft.
deep
For
Orb ;
be
not
or
charge
Slimy
30
Tailings.
charge
of vat
:
22J
ft. diameter,
tons.
Freely-Percolating 100
Size
—
Tailings.
—
Depth
of
vat,
10
ft. ;
tons.
1200
2 vats .
.
.
tons
.
.
per
month.
2400
4 »
3600
6 j"
.
""
.
4800
8
In case
small of
a
plants
temporary
it is advisable
breakdown
to
in
have one
a
of the
spare vats
leaching in
use.
vat
in
THE
APPLIANCES
PLANT
AND
OF
COST
The
67
EXTRACTION.
CYANIDE
FOR
PLANT.
cyanide plant depends largely on the locality, the material used in the construction, and, to a certain extent, on For the condition material of the be treated. to example, a month will cost 2000 of tons plant to treat dry-crushed ore per than more a plant to treat 2000 tons of tailings. The approximate cost of plants of different capacitiesin Australia and
of the
cost
New
Zealand, of the
For
when
above
Ore
the all
and
The
of steel
cost
The
steel
and
4
of
cost
the
ft.
At
about the
Johannesburg
:
—
laboratory,assay,
the
£10 cost
the
is about
vats
leaching vats at deep, with central
foundations
wood
iron
or
struction con-
below
buildings,is given
for
appliances melting furnaces, the of a cost include but does not cyanide plant, wheel or sand-pump for elevating sands, etc. and
the
in
—
include
estimates
used
material
vats, foundations, and
Dry-crushed
The
is the
wood
same
discharge,
that
as
16
£56
cost
successful
bucket
Waihi-Silverton,
the
a
tailings of
wood.
ft. diameter
each, and
the
each. of
a
cyanide plant month.
treated
Thus
is about
25s.
per
plant to treat per about would 3000 of tailingsper month cluding cost tons £4000, not inand the of tailings wheel cost or smelting offices. assay smaller in the is cost For Hand proportion. The larger plants be roofed should not it noted, are over as they cyanide plants, of
ton
are
tailingsto
in many In
America
be
other
steel
a
countries.
leaching
vats
cost
about
3£
cents
per
lb.
free
68
THE
board
on
£67.
about
cost
Thus
oars.
100
CYANIDE
100
a
the
vats
9400
weighing
vat
ton
wood
red
For
PROCESS.
is
cost
200
:
—
F.O.B.
£42
tons
follows
as
would
lbs.
80 „
.
.
.
.
„
.
500
120 „
„ ?
The
American
They which
(that bottom.
40 is
red
are
gals., the
inside
wood
vats
coated
generally costing
only),
£8, two
is
stated
are
with sufficient coats
to
P. to
on
the
and
give B.
coat
sides
every Paraffin
a
500
and
tion. satisfac-
paint, ton
three
of
twice
vat
on
the
70
THE
In
the the
to
flow
the
of
case
in
a
dry-crushed
from
mass
the
over
below, surface,
solution
strong
but
from
two
to
for
contact
to
meate perallowed it is tailings
of
case
downwards.
soak
iu
is allowed
solution
iu the
takes
stand
to
the
ore
and
generally
tailingsit is allowed
PROCESS.
CYANIDE
The four
fillingof With
hours.
twelve
after
hours,
which
With slow artificial percolation is begun. dry-crushed ores at once. percolation is commenced The takes from leaching with the strong solution twenty-four of the to forty-eight or more hours, according to the character bullion in the of ores case containing a proportion of fairly ; but the make it is the strong solution to coarse gold, customary to up working strength and pass it through the charge till an adequate extraction The
is obtained.
cyanide solution, often called the first wash, is then and the from generally applied. It is pumped strong sump, varies in strength from of 0 1 per cent, 0*25 to potassium per cent, It is allowed tration to percolate as rapidly as cyanide. possible, the filof an artificial being facilitated,when by means necessary, which be aircreated exhaust, or an by a steam vacuum, may connected with a vacuum-cylinder. pump The first weak three is succeeded or by two cyanide wash washes of solution from the weak 0*02 containing from per sump, of KCy. cent, to 0*1 per cent, A final washing of clean is then water applied, which serves the to displacethe preceding weak cyanide wash. By this means remains in circulation much about quantity of cyanide solution the
weak
same.
it is sometimes advantageous pyritic ores solution the before solution. to apply a weak cyanide strong By this means and a a larger extraction saving of cyanide is effected. is about one-third The used of quantity of the strong solution the and of the The water-washes each weight ore. cyauide are about one-sixth of the weight of the ore. of slimy tailingsit is found During the treatment advantageous the material to sometimes and turn hand-labour, over by thereby effect a more from complete washing out of the cyanide solutions the slimes, which and retain always have a tendency to entangle them another and transfer it from to to vat or even one subject to second a leaching. In
the
treatment
of
Discrepancies between are
often
a
but
source
in most
of much cases
imperfect sampling or weighs considerably over At
the
the
Witwatersrand
theoretical
annoyance they will
incorrect 2240
and
and be
actual
extractions
perplexity
found
tonnage.
to
At
be
to
the
due
most
lurgist, metal-
either
mines
a
to ton
lbs.
Goldfields,
in
South
Africa,
the
tailings
ACTUAL
THE
subjected
sometimes
are
cyanide
treatment
the
again
treated
vats, and
white
labour
with
of
difference
would
first
the
other
leaching will
extraction the
cover
of
cost
this
extra
Rand
the
on
amounts
where about
to
is raised
to 85
72
said
high-priced
cent., and per With tailings
cent.
per
is,however,
recovery
only
leave
to
a
margin
profit. The
be
the
i.e.,after
—
cyanide.
treatment
of fair value
treatment
charged into cyanide. A higher
available,
was
double
71
CYANIDE.
are
if the
extraction
average
BY
double
a
with
and
handling
extra
The
to
residues
it is doubtful
result, but the
EXTRACTION
tabulated
follows
as
1.
Filling the
2.
The
3.
Leaching
different
the
which
in
sequence
operations
applied
are
may
:
—
leaching
vats.
with
preliminary treatment
water
alkaline
or
washes
if
necessary.
cent,
4.
to
First
5.
per
Second
6. Third 7.
Fourth
8.
Fifth
The
solutions
same
in the
carried
through
the
most generally carry the through strong
weak
from
sump,
containing
from
KCy.
cent.
dissolved
ore
are
out
by
allowed
the
the
the
by and
first
tion, strong solu-
second
washes.
flow
to
box.
the
ors, through the zinc extractthe weak strong box, and
The
first
dissolved
washes,
two
bullion,
which
conducted
are
extractor.
FIRST
of
containing
water.
weak of
sump,
KCy.
cent.
from
through
solutions
per
last.
clean
are
strong
per
as
same
0*3
second.
as
with
or
from
per
0'1
from
containing
KCy.
cyanide to
solutions
strong
0'26
to
with
silver
removed
cyanide the
wash, wash,
of
cyanide
cent,
wash,
gold and
cent,
per
and
per
solution
strong cent,
with
wash,
0*02
The
0*6
wash,
0*1
the
with
STAGE.
with Dry-Crushed Filling the Vats the charging of the vats dry-crushed ores, clouds
Ore. is
a
—
In
the
case
simple operation,
to be dust, seem only disadvantage being At Waihi inseparable from the handling of dry-pulverized ores. generally charged by trucks 90-8tamp mill the vats were running to a traveller,provided with hand-traversing gear so as to enable on In order the sand to to be tipped in different parts of the vat. the from trucks the sand to discharged on was prevent packing, below the fixed main traveller the platform of a small traveller. the pulverized material was dispersed in a gentle By this means
the
the
shower
over
the
whole
vat.
of
which
72 At
by
vats
dry pulp is conveyed from the mill or by belt-conveyors, both very
the
plants
some
screw-conveyors
methods
of
PROCESS.
CYANIDE
THE
to
the
efficient
transport.
N.Z., the Cyanide Works, Kuaotunu, Kapai- Vermont the situated filled directly from dust-bin, which vats was were of a chute, provided in an elevated overhead position. By means with was evenly spread over canvas joint,the material a universal At
the
the
vats.
When
the
smooth
method
the
workmen,
Filling the disadvantages
All
One
—
of
the
stamp-mill
the
even
ores,
rake
or
advantages
the
it.
over
hand-
over
healthier
serious
most
is the
tion produc-
silicious,form
most
; and
wet-stamped
when
slimes
made
was
dust.
with
wet-crushing
of fine slimes.
ore
expeditious,and
Tailings.
with
Vats
the
hoe
many
less
it raises
of
wooden
wide, shallow
a
as
of
surface
fillingpossesses It is cheaper, more
of
trucks.
fillingby
the
charged
was
by passing
This
for
vat
when
clayey
a
portion pro-
earthy oxides are associated with country-rock, iron or manganese excessive. the ore, the proportion of slimes is often slimes In many valuable, sometimes are even places the very In than the sands. they prove more so leaching processes very with interfere the percolation and refractory, as they seriously both to be costly and washing, thereby causing the extraction the slimes are irregularly distributed through imperfect. When channels the sands form the cyanide solutions through them, and result. the natural imperfect leaching is At the Witwatersrand Goldfields, where wet-crushing, followed by copper-plate amalgamation, is at present universal, there are the tailings before in use for dealing with methods treatment two with the pulp from cyanide. The copper-platesis lifted by a bucket wheel, run through a launder, and then classified by vpitzkasten or products, namely: spitzluteninto two and 80 Sands slimes, (a.) per cent. sands, 20 per cent. containing some (b.) Concentrates The collected in a storage tank, and kept under concentrates are of
or
matter,
—
to
water
cyanide vats Filling
the "
the
extensive the
Company, and
then
now means
off
The the
by from
of two
process works
by
or
sands
and
by
what
either
treatment,
into three
tons.
free
the
"
the
slimes
pass
is known
Intermediate
as
Filling
Estate
to
on
the
"
process.
Gold
Langlaagte Mining the are concentrated, leaving plates, ing large settlingdams, each capable of holdof
the
tailings,after
run
7000 carried
for
"
Direct At
while
prevent oxidation,
sands
overflow, slimes,
endless
are
settle and
in the
allowed
hauled
steel-wire
ropes,
dam, to run
from
and
while
the
away.
the
dams
run
up
slimes
The in to
an
are
tailings, by
trucks
overhead
ACTUAL
THE
tram-line,
ready
for
from
which
mines
32
73
CYANIDE.
the
into
leaching
vats
are
and
shape, the
of
there
feet
square these From
11
mill. are
ft. in
per
Princess, and
Robinson,
many
tailings,after being subjected settling-tanks,which for the sufficientlylarge and numerous the At Robinson plant, treating 330 intermediate
into
run
the
the
Johannesburg,
in
requirements tons per day, diameter, and
At
—
at
circular
are
dumped
are
Filling1.
concentration,
to
they
BY
treatment.
Intermediate other
EXTRACTION
wooden
circular
six
This
depth.
24
vats, each
gives
ft. in of
settling surface
a
stamp.
intermediate
the
buted distritailings are When the slope of the ground the leaching vats, placed above
settling vats
the
leaching vats. permits it,the settling vats are the tailingsbeing discharged from when holes in the bottom ; but level the the of below the they are leaching vats, tailings are actuated hauled trucks wire endless in by up ropes. the To ensure of in and distribution sand slimes a fairly even the leaching vats, a simple and distributor, ingenious automatic in use " Mein, is now in all parts of invented by Messrs. Butters the world. It consists of a central casting, with a vertical spindle conical the in and a foot-step, carrying a hopper at revolving top, from radiate twelve iron with bent which sixteen ends. or pipes To These in. in size from to 1£ 2£ in. in diameter. pipes vary their attached flattened in nozzles assist to discharge ends are wide A coarse is placed a area. screen spreading the tailingsover the to central hopper, or bowl, so as over or pieces prevent stones the The of wood, or other from distributor debris, choking pipes. to
is fixed
on
reaction
an
the
of
iron
column
insure
before
water
with
settle the the
success,
similar
machine vat
is
to
the
V.,
the
carry
sand
off the
and
the
until
running,
the
there fine takes
be
must
be
of
filled
place
the water
continual
a
The
slimes.
the
VI.)
overflow must
of
vat, and
it to pipes causes an ordinary garden
otherwise
pulp,
the
bent
that
to
Plate
the
of
centre
collectingvat
admitting
the
the
from
pulp escaping
slowly revolve in a manner sprinkler. (Fig. 4, Plate To
in
with
slimes
would
began.
While
overflow
discharge, or
all
clean
of
from
overflow,
the
ference, circumpoints annular into an ring, surrounding the top it to the of the of slime-pit. The overflow vat, which conveys the until is full of sand, therebe continuous vat fore, slimes must should the when battery stops, a regular quantity of water from
still be The water
six
settling vat being received
supplied to the vat. vats are provided with is allowed
hours
before
to
drain
at
filters,and
off for
fifteen
discharging, holes
are
when
full of
tailingsthe or twenty-four hours, while the to dug down discharge
74
doors
let
to
discharged into doors, or
the
"
where
house, At
the
in
a
the
through the whole The advantages (a.) By means collected
claimed
for
leaching vats. (quicklime ground
that
way
it
intermediate
(The
quantity and
tanks, slimes
of of
size
bulk
the
condition
the
the
are
slimes of
nature
on
sands
during
thus
being
in
that
little
the
the
for treatment,
pyrites
extraction
fine
contents
(e.)The
sands
is very
slight, so
cyanide
consumed.
be
(d.) A higher of
—
battery-box. )
the
of
:
of
depends
best
will
gets distributed
intermediate
discharging through the bottom, operation get thoroughly mixed,
(c.)Oxidation
be
can
which
sands, from be
can
obtained
cost
extracted
owing
85
the
to
of
cent,
per
presence
the
gold
by cyanide, small.
is very principal disadvantage is the
The
the
of lime
a
tank
the
into
run
into
fillingare distributor, nearly all the
the
of
in the
size of screen,
(6.) When
emptied amount
such
in
then
are
mass.
escaping. ore,
vat
are
required
ball-mill)is added
drained, the tailingsare charge below, through "bottom-dis-
which
trucks,
contents
time
When
out.
leaching
into
their
same
flow
water
more
PROCESS.
CYANIDE
THE
of treatment
tendency of the distributor to form deposits of slime, through irregular distribution, at places the bottom of the tank, thereby causing some trouble on, or near, in draining off the water. Direct
City
Filling. —
This
and
Suburban, and Witwatersrand,
method
Crown
is
Reef,
in and
the
at
use
other
works
companies pulp, as it
of
the
at
the
leaves conducting the the copper-plates,into a classifier or spitzlute. In this the pulp is and the overflow, carrying slimes divided into two streams : oue, fine sands other, carrying the coarse sands, together with ; the sand and fine which slimes, some are conveyed by an india-rubber hose to the leaching vat, where they are distributed by moving the
hose
carried
over
off
the
area
of
and
the
fitted
The
vat.
inside
of
excess
the
water
vat, taking with
is it
slimes.
for direct fillingare advantages claimed exposed to pyritic tailings are
The 1.
whole
in
by adjustable gates
fine sand
some
consists
That
:
—
the
minimum
of
oxidation. 2.
A
3.
A
second
handling of rough preliminary the
The 1.
the
tailingsis
classification
avoided. is
effected,thus
ing separat-
fine slimes.
principal disadvantages of this method The packing of the tailings, which water. draining of the contained
are
:
—
prevents
a
complete
M
X
o
3
'
76
THE
The
generally used at the Thames,
author
Works
soda, zinc,
be
must
attended
it is not
as
which
fouls
the
when
extraction
lime
sulphides
not
are
it
On
extractor.
addition
the
that
mental Experi-
preferable to caustic production of ferrocyanide of
found
the
in the
Government
the
at
and
with
zinc
remembered
PROCESS.
CYANIDE
in
present
hand,
other
it
only improves the the material being
lime
of
the
treated. When
the
is certain to cyanide contains sulphide, the extraction the slow and unsatisfactory. The on sprinkling of lead acetate the tank of will the the sulphide as precipitate sulphur of top lead sulphide, thus the from free sulphide. leaving cyanide In the case of very acid tailings,Feldtmann strongly condemns ing the practice of conducting the preliminary washing in the leachof the account vat, on possibilityof the acid acting on the residual cyanide in the vat, and thereby liberating sufficient an hydrocyanic acid to dissolve appreciable quantity of gold, which would he says be lost, as it is not precipitated by zinc. He be effected in one vat, and suggests that the washing should the that the of costs extra leaching in another; and considers made than handling would be more up by the higher extraction. if hydrocyanic acid has any It is doubtful action on gold ; but it is probable that the ascending acid by uniting with any alkali alkaline form would at once react an cyanide which present would on gold to which it had access. any be
STAGE.
THIRD
Solution
Strong
solution,
strong
Leaching.
about
one-third
generally containing from potassium cyanide, is When the
stop-cock is
then
In
After
the
shut,
off, and
drawn
generally through.
stands
solution
the
takes
case
from
of
the
0*2
per allowed
and
the
nitration
tailings,the
to
drawn
off to
assist
lying
diffusion
below
The
solution
allow
hours, standing of lumps slimy material, the passed through the zinc extractor. to
solution
the
of
and
to
to
the
ore
filter
the
is
solution
percolate
added
is
on
top.
permeate
drained
slowly off, are sionally occaquantities solution through the is
Small
of
strong
solution
the
charge,
surface
thirty-sixhours
strong
all the and
the
commenced.
the
ore,
able of availcent, per the vat from below.
into
pass above
solution
twenty-four
twelve
to
0 5
to
the
of
weight
cent,
inches
two
dry-crushed
With
—
mass.
It is sump
a
very
common
practice to apply
containing,say, 0*05 the intention being
to to
0*10
before
allow
the
a
weak
solution
applying acids
and
the
from
the
strong
tion, solu-
foreign
matters
THE
destructive
ACTUAL
EXTRACTION
BY
77
CYANIDE.
the weak solution, cyanide to expend themselves on before applying the strong solution. the ore When contains from a large proportion of silver say, five to eight parts to every found it will be sary necespart of gold to adopt one obtain of two in order to courses a satisfactory to
—
—
extraction.
Either
a
used
to
be that
greater bulk
much leach
of the
the
taken
ore
ore
say, else a
solution
potassium cyanide a quantity equal
—
or
—
of
in
weight
to
must
be
stronger solution
much
must
used. The the
these
former, only, of contained
two
would
courses
be
applicable
if
small
oxide, carbonate, proportion of copper the bility soluof of since or sulphide sulphide, or antimony, of cyanide, but of these in all solutions especially in the render fair extraction a strong, would impossible, besides causing a
ore
heavy The
than more
loss of cyanogen.
sulphide gold, and expensive On
ores.
a
even
the
of silver
ores
this
for than
other
of
hand,
the
silver)is more readily acted 80 exceeding per cent. In the practical treatment of the the
first anomalies
fact
that
speak, yet and
the
does
second
to
carry
cyanide
It is found
on
of
attract
treatment
ores
and
the
notice
strong solution, not
soluble
in
cyanide always ordinary tailings or gold-bearing of silver chloride (kerate or horn than gold, the extraction generally the
reason
that
slowly
more
are
while this
it away,
of
such
is
tailingsby cyanide, one of the metallurgist is the it loosens gold, so to being effected by the first '
*
washes.
portions of the strong solution,draining from the charge, contain only from 0*02 per cent, to 0*1 per cent, of the off stronger and cyanide ; but remaining portions come the stronger after a lapse of eight or twelve hours, until, towards end of the the maximum is reached, strength strong leaching, after which the strength declines before the little a application of the first cyanide wash. solution The first portions of the during the strong cyanide in cyanide and low in gold, are, leaching, being weak therefore, the the weak while later portions, zinc passed through extractor, with the first and second conducted cyanide washes, are together the
to
strong
It will in
that
be
first
extractor.
found
dissolving gold
the
the
in than
used
become
zinc-extractors
fresh
practice that
solutions
charged
with
solutions which
the
in inert
are
more
active
passing through zinccompound
potassic-cyanide.
Strong has
Sump-Solution
completely
drained
Wash.—
off, the
strong
After
the
strong
sump-solution
is
solution
applied
78
CYANIDE
THE
from
above, being
in
run
strength varies from the quantity applied of the
0*1
PROCESS.
the
on
top,
one-third
from
0*25
to
cent,
per
to
the
of
surface,
or
of
cent,
per
of
one-quarter
Its
ore.
KCy, and the weight
ore.
weak
This
solution
is sometimes
through the charge, but as possible, for the more
allowed
it is drawn
often
more
to
slowly percolate off as rapidly
solutions rapidly the wash off the effective is the The nitration more washing. the the bottom of stop-cock connecting by opening with the vacuum-cylinder. vat The percolation of the weak solution generally takes to twenty hours, the time depending on the condition forming the charge.
Weak
Water
and
Cyanide
Washes.
will
of these
is assisted the
leaching
of
and
sump,
wash
cyanide
and
from
one
quantity of each strong cyanide solution. effect
of
the
by assaying
other
; in
of
the
wash
in
is
most
washes
residues
and ore,
necessary the from whole
followed
by
the
from
a
weak
washes.
water
different
pulp
the
the
cases
strong
final
The
The
wash
water
cyanide leaching a cyanide wash strong sump,
the two
or
final
a
of the
consists
treatment
sump,
then
the
number
character
depend entirely on strength In some it is found cases or tailings,being operated on. three four weak to apply as many or as cyanide washes, weak
twelve
from
The
—
the
drawn
are
one-half
cases
should
that
of
be
mined carefully deterafter each washing, and also the from the the vat. By this means
they drain number of washings will soon be ascertained. necessary The of the charge sample should represent a fair average assay in the is easily and reliably obtained vat, and by taking a large number the full depth of the charge, by means of cores, of a tube like cheese be should a shaped something sampler. The scores down dried for and then sampled assay. aim the of the different solutions which Briefly summarized, have in the been applied to the material leaching vat is as solutions
wash
follows
as
:
—
(a.)
Alkaline of
waste
wash,
with
different
The and
the
direct
method
and
to
Dry
2.
Cyanide
acidity
solution
effect
prevent
so
to
as
prevent
water
of
washes,
cyanide
from
gold, to displace cyanide being thrown away
residues.
operations
to
of treatment
crushing.
1.
to
and
solutions
solution
neutralize
cyanide.
(6.) Strong solution, (c.) Weak
to
treatment.
be
undertaken may
be
in
summarized
the
dry-crushing as
follows
:
—
THE
ACTUAL
3.
Copper-plate
4.
Concentration
5.
Treatment
With
EXTRACTION
of
amalgamation tailings
of of
79
CYANIDE.
tailings.
from
plates.
concentrates.
the
wet-crushing
different
1.
Wet-crushing.
2.
Copper-plate
3.
Concentration.
4.
Treatment
of
concentrates,
5.
Treatment
of
tailings
6.
Treatment
of
slimes
operations
are
:
—
amalgamation.
When
Remark.
BY
by by
by
leaching
cyanide
other
or
means.
cyanide. cyanide. sands
slimy
the
successive
solutions
—
and
should
washes
samples
assay
to
subsequent
so
as
of
sand,
its
easy
a
said
replacement
partially
drained,
If
fine
taken.
very
drained, Hence
solutions.
leave the
be
thoroughly
be
slimes,
to
to
be
only
cushion
or
jacket
jacket
preventing by
the
solution
is
of
sands, become
they it
sufficient
just
to
and
allow
ing contain-
impervious partially
round
solution
following.
sands
almost
important
packing
or
to
thereby
each
drain
particle permitting
CHAPTER
TBEATMENT
THE
With of
all
methods
certain
a
ore
a
of
valuable
the
on
of
attention
been
has
much is
the
thought
and
and
the
at
a
is
certain
generally
has
engaged
wet-crushing,
of
number
a
the
slimy the
years. culty diffi-
the
in
consisting
one,
author
the
which
to
for
permit
attempts
many
from
one
from to
the
are
process,
experiment
as
slimes
resulting
subject
cost
matter,
years.
cyanide
solutions
such
the
a
treatment
many
when
containing the
gold,
mechanical
a
earthy
ores
slimes
and
separating
effectively,
for the
the
principally
or
successful
of
scale,
problem
low
their
leach
to
economic
of
of
and
metallurgists
made
devoted
The
or
other
formation
and
inevitable,
In '
float
*
introduction
the
an
fine
very
clay,
the
pulverizing
seems
large.
very
product,
Since have
often
is
proportion
oxides,
SLIMES.
and
slimes
of
metallic
production
OF
wet-crushing
of
proportion
contains
VII.
rapidly,
mass,
slimes
of
treatment
value.
Up
the
to
tried,
with
present
force
filtration,
by
an
is
battery
that
be
leached
can
by
ores
slimes
have
these
presses and
;
be
may ;
been tioned men-
and
agitation
with
agitation
vacuum.
attended
always of
proportion material
of
other
decantation
artificial
dry-crushing
The
and
and
agitation
;
aided
devices
Among
success.
hydraulic
by
compression
different
many
of
degrees
varying
centrifugal
great
a
the
with
only
Californian
production
shallow
a
in
the
of
means
depth direct
the
of of
stamp
large
so
the
a
pulverized
method
cyanide
of
treatment. The stands a
battery
stamp
unrivalled
the no
In
New
mill,
all
dust better
Zealand the
best
all
for
unscientific
most
invented
was
classes
machine, when
reduced
has and known
yet
for
been
of
For
ore.
of
account
on
to
the
which
for
dry-crushing its
requisite
inability
to
fineness.
it is
it
charge dis-
theless, Never-
invented.
Australia roll
wet-crushing,
every
machines, 80
variety and
of
pan
pulverizers
and of
ballmany
!
j
TREATMENT
THE
different
designs have
soft and
friable,and
discarded which
the ore tried,but, except where was is to produce slime, all have
very been
object
for the
known at present stamp, which is the only machine with the hard to cope successfully quartzose ores. depth of dry pulverized material placed in the leaching
is able
The
seldom
vats
silicious
exceeds This
ores.
small for
ton
been the
81
SLIMES.
OF
feet,
the
favourable
most
a large plant correspondingly greater
to
a
and
of ore,
output
with
even
a
treat
tively comparacost
per
treatment.
Author's
Experiments
of
parcel The
three
necessitates
from
ore
consisted
ore
:
of
Early
—
hard
mine,
bluish
treated
the author
in 1893
Monowai
the
and
in
a
large
district.
Thames
the
grey-coloured splintery
quartz, containing a considerable proportion of sulphides of iron, copper, lead, and zinc. The dried, dry-crushed, sampled and ore was assayed, showing in a stamp value of £5, 5s. per ton. The effected a crushing was
battery, which These
slimes
produced rendered
percolation,even water, I
the
forming The
a
it
with
the
aid
when
slimes,
only impervious bed,
an
to
draw
pulp
was
off the
of bullion
of
a
the
it
slimes.
leaching by mixed
the
on
which
through
finest
When
vacuum.
thick, settled
4 in.
with
filter-cloth, found
was
possible im-
solution.
subjected
then
the
large quantity of impossible to effect
effected
which
agitation,by
to
in six
the
tion dissolu-
The
hours.
separation a long and tedious pulp, however, was over operation, and extended eight days. It was effected,but not satisfactorily, by agitating the ore, allowing the slimes to very The settle,and then drawing the clear solution off by a syphon. of the
was
solution
weak
solution
from
and
In
order
wash-
waters
reduced
was
with
and
a
it
With A.
C. With A. "'
L».
D.
when
crushed,
a
found
that
60-Mesh
18%
the
o/0
of
an
fineness
to
on
were,
in each
case,
...
a
on
»
»
„
„
100% passed through
...
....
....
a
which
the
ore
of
—
remained
the
made experiments were ordinary battery-punched screen,
number
results
100% passed through
22% ™/o
succession, and
—
remained
40-Mesh
in
each.
degree
60-mesh, 40-mesh, and was
added
were
after
the
ascertain
to
seven
the
operation performed
same
or
.
as
follows
:
—
82
With
THE
CYANIDE
Punohed-Sorebn,
equal
the
Taking that
found
values
the
received
also
dust,
in all
finest
confirmation
The
From
The
nearly
9,
1893
patent be
gold
the
for
a
described
in the
material
.
.
.
.
silver
in
the
from
ton.
per 13
6 „
pulp from platform 1
the to
dust-bin thus
12,
was
showing
contents.
author
obtained,
with
agitation and
follows
during
bin.
—
.
dust
fine
:
.
silver
to
combined as
dry
follows
platform
6
in the
and
of the
increase In
of
1 to
as
elevated
an
the
was
This the
that
.£550
platform,
ratio
than
were
dust-bin,
„
an
values
relative
on
values.
highest
gave the circumstance
from
crushing, assayed higher
products separately,it the
cases
collected
had
which
30-Mesh-
to
different
the
of
PROCESS.
his
of
two
leaching
assistants, which
process,
a
may
:
—
the in shallow of a operation consist appliances used The and is circular vat an vat, a vacuum-cylinder, air-pump. soft rubber which to brushes provided with four revolving arms, The is provided with false bottom of the attached. vat a are with bottom, consisting of a wooden wool-packing grating covered The The follows : other webbing. as or operation is conducted is the first leaching solution, made required strength, ducted conup to The then in into the vat. set are motion, revolving arms and introduced. The the dry pulp or fine slimes tinued agitation is conA is complete. for six hours, or until the extraction cock, stopthe of the false-bottom and in a pipe connecting the vat The vacuum-cylinder, is then opened, and the air-pump started. clear solution is The immediate. effect at once begins to drain the the into the brushes over vacuum-cylinder, on revolving arms the and slimes from choking up the filter-cloth. preventing settling
The
—
When
the
first wash as
slimes
been
down
to
a
thick
again started, and the added, the pump The are subsequent washes applied in the the washing is completed, a plug or door
and,
when
the
leached and
slimes
are
sluiced
washing takes was adopted process
leaching
drained
is
before.
This
have
from
by
out.
The
eighteen the
author
to
paste,
slimes
the
drained
same
is
manner, opened, and
whole
operation twenty-four hours.
of
for
of
the
treatment
84
CYANIDE
THE
Acting
on
obtained
author
thrown
suggestion
a
Mr.
from
Mining Company, the showing the relative values These the pulverized ore.
Wichmann,
of
number
a
of
the
experiments,
different
degrees
are
instructive.
fineness
of
relative values degree of fineness and reduced ore was by stamping through
to
of
results
very
of
Value
0-36% 2-16% 9*29%
B. C.
remained
on
74-28% passed
„
(1600 holes)
60-mesh
(3600 holes) (6400 holes)
„
Similar
Experiments
0*3% remained 7-8% 14-7% 85'3% passed
C.
40-mesh
80-mesh
25-72%
D.
(900 holes)
„
„
E.
B.
30-mesh
„
„
D.
A.
Waihi
30-
Screens.
mesh
A.
the
showing "Martha"
which
the
C.
metallurgistto
Banks,
results
Mr.
by
out
G.
E.
Gold
Experiments
PROCESS.
on
„
„
„
„
40-mesh
£4
6
2 3
18
3
11
10 2
4
9
0
5
7
1
Screens.
40-mesh
(1600 holes)
60-mesh
(3600 holes) (6400 holes)
80-mesh
7
3
12
3
7
3
11
4
3
19
2
11
.
„
„
showing
Experiments
with
Ton.
per
value
Dust
of
rising from
stamp
—
Dry -crushing. Value
obtained
Dust
A.
floor
from
B. ""
"»
j"
»"
""
""
C.
Average
different
The be
classified
processes follows :
as
Decantatiotl,
1.
high
10
ft. to
20
ft.
20
ft. to
30
ft.
30
ft. to
40
ft.
40
ft. to
60
ft.
which
from
ore
10
ft.
high
Ton.
per
£6
16
4
7
2
4
7
3
1
7
19
8
13
11
""
E. of
to
)"
D.
value
of mill
of slime
this
dust
4
came
treatment
at
present
in
8
1
use
4
may
—
practised
as
in
Africa, America
and
New
Zealand.
New
and 3. 4.
Sun-drying.
Rand the
features
as
practised
in
Western
Australia
Zealand.
Electro-chemical
Central Robinson of the
precipitation. In
Decantation.—
at
method,
Filter-press
2.
Ore
1896
Reduction
mine, treatment
at
Mr.
C. Butters, then
Company,
erected
the
cost
of
are
the
classification
nearly
"£ 6
a
manager
large
0,000. of
the
of
slime The
the
plant salient
slimes
into
TREATMENT
THE
three fine fine
85
SLIMES.
OF
consist of products, which while the treated in sands, are vats; by ordinary leaching slimes with leached in vats revolvi are agitators, by a proug cess The author 1893. Zealand the in patented in New early by
products.
agitators
The
about
are
second
first and
10
ft. in
provided
and
diameter,
nnd
filter-frame
with
a
is drawn
solution
webbing. During agitation the with an a vacuum-cylinder. by means air-pump connected A fuller description of this process is given further on. On the Rand, the treatment of slimes has naturally been a very and serious much time problem, to the solution of which money have been The of devoted. treating slimes, following method off
of
known
the
as
Crown
the
Reef
the
by
Robinson
slimes
from
being is regulated by the
ft.
slimes
a
automatic
an
it
with
carrying
of
the
milk
lime
the
slimes
supply
much
too
the
lime,
The
It
adopted
water,
form.
feeder, as
interferes
into
first two
The
vats
conical
slimes a
two
of
lime
as
bad
is
precipitation of
efficient
are
More
by allowing jet of cyanide 0*1
About
filled with
percent, 80
32
per
been
and
solution,
drawn
slimes
are
then
90
the
and
ft.
pumped of the
cent,
per
10
deep, having a the separated from
10
are
transferred
and
40 ft. and
x
bottom
been
ft.
sluiced to
strength
into
of which
pump
series
second
a
a
is
of
brought
KCy. of
the
gold is dissolved agitation is continued
but through the pumps, hours by withdrawing the solution at the it in oblique jets at the top and through The
the
and
settle,they
to
ft.
of them
two
separated.
having
water
40
vats, about
ft. in diameter
solution
of
off at
treatment
having
them
cent,
third
the
drawn
are
in them
large pointed boxes,
and
deep,
eight
each
bottom.
vats to
in three
slimes
of
contained
water
10 ft.
settled
The
the
settled
are
ft. and
20
x
deep.
up
flocculent
at
use
gold.
The 20
precipitated in
afterwards
and the
To
in
satisfactory results.
separator plant, is added
little,since
too
as
Works.*
been
has
process,
1896, with R. Williams,
J.
Slime
the
thus
Mr.
by
"
settlement
August
since
first devised
was
by
natural
"
allowed
to
in from
bottom the
settle, and
and
the one
passage to
two
discharging
sides. the
clear
off
solution
is
through side-cocks (which have been replaced by syphon pipes at the Robinson Works) and passed to the precipitationboxes. The residual slimes then are pumped successively into the and fourth third series of two further vats, where they are with dilute solutions to of agitated cyanide and allowed very These solutions do settle. the not to precipitation boxes, pass but transferred to the preceding series of vats. are *
Chem.
and
Met.
Soc.
of S. Africa, July 1897.
86
PROCESS.
CYANIDE
THE
is run the series of vats second "strong" solution from and into two 5 ft. deep, where settling tanks, 15 ft. in diameter From it is allowed to clarify. Electrical precipitation is used. of '5 6643 tons actual extraction cent, 60 was treated, an per of at 3s. cost 9d. ton. a obtained, per concentration of the solution The as regards its gold contents when first successfully introduced decanted, was by Mr. J. R. Williams the amount Reef at the Crown plant, in order to reduce of solution boxes. Naturally, passing through the precipitating the when solution from in obtained of is amount a gold given be slimes of gold can centrated conper twenty-four hours, if this amount volume into small of solution, a small a precipitating Williams introduced Mr. capacity is required. For these reasons the system of double washing ; that is to say, the first solution clarified and that the is not is applied to slimes after decantation what is into passed through the precipitation boxes, but is run called intermediate tank," and then pumped an again up for use fresh second it slimes. this After of decantation, a charge upon is run through the clarifyingapparatus to the boxes for precipitation. The settled slimes then re-pulped with an equal volume are which of solution from the is, solution precipitated sump ; that has passed through the Theoretically, the precipitation boxes. of the unprecipitated solution enrichment could be carried on until it was equal to the value of the slimes, but in practice it has
The
"
been
found
and
the
that
the
second
wash
make altogether),
South
the
African
wash
Practice.
1. 2.
Spitzkasten
3.
Collection
Rand
the
1901, is based the
from the A
slimes
of
the
some
of the
Company best
:
—
slimes
in
collecting
vats
vided pro-
solution. of
for
solution
tation. precipi-
agitation is generally effected by cases revolving stirrers are used.
the in
follows
as
slimes.
decantation
Practice. Waihi
on
separation
the
but
are
tion decanta-
of the
features
of slimes.
and
slimes
Zealand
adopted by
and
sands
settlement
mines,
centrifugal pump, New
Africa
decanting syphon. with cyanide
of
5. Settlement
the
main
of slimes
Agitation
At
South
not
perfect system.
most
The
been
precipitated, precipitated (two washes
been
and
—
concentration and
with 4.
has
simplest
practised in Spitzluteseparation of
has
which
which
as
process
at
first
South
—
The at
method their
African
of mill
new
at
treatment in
Waikino
practice,differingonly
gold-containingsolutions
instead by filter-presses
slimes
of
which
repeated
a
are
in
separated
decantation
as
Rand.
detailed
description of
the
methods
of slime
treatment
at
the
THE
Company's
Waihi
E.
Filter-Press
that The
application. the
oxidized
past
scarcity
of
found
be
in
process
has
years,
but
few
received
has
it
will This
—
the
during
by the company's Chapter XII.
stamps, furnished
Banks,
Practice.
Zealand
Australia
G.
87
SLIMES.
OF
of 320
mills
metallurgist, Mr. New
TREATMENT
widest
its
and
water
successful
most
clayey
in
Western
it is in
and
the
revived
been
character
of
tropical country presented a difficult the with problem to the metallurgist and chemist. Compared decantation extraction is being obtained, a higher average process, with lower the value of the of but water a consumption ; assay residues is higher than in South it has been Africa, where duced reA consideration low as 9 J grains of gold per ton. of the as the higher extractions that at Kalgoorlie are due practice shows the slimes treated. to the higher grade of of the The Details as of Process. following details process Australia instructive in Western from extracted are an practised of the Donald Mr. Director Clark, recently published by paper in Victoria.* Bavinsdale Mining School The at ore Kalgoorlie, as a rule, is dry crushed, Krupp's ball mills being mainly used ; after crushing, it is wholly roasted. the Several field, including the shaft are on types of furnaces Mount at furnace (similar to those Morgan), Brown's, Ropp, It is notemechanical furnace. worthy Holthoff-Wethey, and Edwards' that
of
ores
—
that and
the
last
valued,
is most
perfection in roasting. analysis of typical ore from the appended : cost
its
of
account
on
lowness
in
its
Lake
The
View
Consols
mine
is
—
S
These
usual
of the
pyrites. greatest roasted
flowing
that
the
and
gangue
is not
the
over
sulphides, and slimes *
are
Clark,
a
of this
is favour finding most a hydraulic separator,
into
ore
top,
the led The
while
coarse
into
the
sands
coarse are
to
ore.
Mining
the
pass
the
drawn
the
Standard,
gold partly at
away 50
whole and
fine
gold,
spitzkasten,where
Australian
'11
complex one, since it consists small a comparatively percentage of the of rise telluride to gold gave ore
of presence difficulties in the treatment The
method
The
The
show
results
(undecomposed)
per
Dec.
the cent,
5, 1901.
of
the
slimes
roasted bottom. of
the
88
CYANIDE
THE
flows
water
dried
cent,
of
with
cyanide
sands
from
then
which
sand
The
treated
concentrates
from
table
the
slimes
; the
sent
plates,
copper
is
are
into
run
vat,
a
The
solutions.
slimes
in
mating amalga-
an
agitators,thence
the
to
coarse
concentrates
cyanide to
per
agitated
it is
over
these
ground
are
are
run
with
way
50
containing
coarser
from
escapes
usual
in the
are
the
where
tables,
mud,
filter-pressed. The
afterwards
hydraulic separator
there
pan
the
agitators,where
into
run
and
solutions
percussion
extracted.
is
slimes,
the
over
and
top clear, and
the
off at
PROCESS.
the
to
filter-presses. The
Dehne
given great in the
market
The
slimes
and
Martin
is worked
press
follows
as
has in use and press has lately been placed
favourite
the
The
:—
in
forced
and through the slime valve passage, their way through the ports or side openings of which they fill up, the liquor escaping by the
are
frames
open
drain
and
find
thence
the
is filter-press
satisfaction.
cock.
When
the
these
plates
full
of
fairly cyaniding then forced in through the be, are or washing, as the case may find their These into the solution channels. solution plate, way the the and are forced from corrugated plate through perforated slime the the the then cake, through through filter-cloth, one, the of corrugated surface perforated plate, and down air-plate the zinc whence should led It be to boxes. stated they are away first air rid that is of the air imprisoned by opening got any escape the air the the and solution. When displacing cocks, by liquid starts to run through the air-cock, the solution plate is closed. When is clear cyaniding in presses, the escaping water enough the led back the be to to separators ; cyanide solutions are forced 90 lb. of inch until the gold is at a through pressure per square caked
is
on
ready
cocks
It takes
gold, and 90 displace any to
for
minutes
are
the
solution
to
passage The cakes
50-cake
tons.
closed.
press Messrs.
for
3-inch
the
for
few
Martin
as agitators, as many through in twenty-four hours, or, in tons day. According to Mr. per without grinding power pressing any 1 -95 dwt. per residues being average
of
Co.
other J.
ton.
are
80
are
words,
Moss, is
slime
the
air
is
press
usually
cubic
feet,
now
50-cake
12
to
and
to
making press holding in conjunction with be charges may put
the
used
are
order
compressed
contains
"
cakes,
In
minutes,
slabs
2 ins. thick
presses from 10
of
the
extract
to
presses.
current
or
for
minutes
such
a
are
Solutions
fill,90
empty three solution, a or
opening. a
run,
then
minutes
to
water
in. square presses When nearly six tons. the
90
wash
and 3 ft. square, three about or 42
to
ceases
The
slime
extracted.
turned
water
10s. The
the 10'2d.
as
much
cost
per
total cost
as
for
60
filter
ton, the of treat-
THE
the
from
ment
put down The
mine
and
in labour
35s.
at
9'4d.
material
tailings dump,
suitable
allowing repairs and
in
cost
if necessary, the channels
all
withstanding
for
first cost
for
is
renewals,
ton.
constructed
be
can,
with
89
SLIMES.
OF
second
per
machines
wood,
or
the
to
supplies and
Dehne
metal
TREATMENT
and
the
corrosive
of gun-
lined
valves
with
of
effects
any
particular material. Details
of the
Diehl
and
Riecken
of which
slime
both processes, found in Chapter
XIII. operation at Kalgoorlie, will be With to Cyaniding. trates previous Roasting pyritic concenand even high grade pyritic ores, a higher percentage of the gold contents always be obtained can by roasting previous to and the Colorado in of cyaniding, and Cripple Creek camp this Australia is largely adopted Kalgoorlie in Western process for the treatment of sulpho-tellurideores. soluble the By roasting, cyanide solutions are kept freer from salts than of gold can when ore treating raw ; a higher percentage in
are
—
be
extracted
and
at
smaller
a
is found
it
that
; the
cost
in
the
The
Only
found
author 30
In
90
per
order
should
to
values
cent., with ensure
them
in
it is
success
roasting
ores,
and
;
causes
filtration
making which
yielded raw state, yielded, when consumption of cyanide. essential the that sulphides concentrates,
smaller
a
is shorter
treatment
clayey porous,
Moanataiari
their
of
cent,
per
roasted,
that
of
case
dehydration, thereby rendering comparatively easy.
of
time
the
be
roast. subjected to a "dead" and if the is dead quick ore satisfactorytest to determine amenable is described to roasted, and cyanide treatment, by * Wallace follows : Macgregor as Take of the roasted at ore samples discharge end of furnace, 200 cool,take from 100 to 250 grams, place in a beaker with c.c. of water then filter into a minute, ; stir this by shaking for about
A
—
"
a
beaker
flask, and
or
the
to
cyanide used in the regular work cyanide solution slowly and quantity
of
cloudiness
solution
all
at
fitted for treatment
cyanide "
salts
If
will
a
brown
of iron
consumption of
*
be
made
up
the
in
the
to
is dead
is best
by cyanide solution,
and
as
that
add
the If
least
at
or
the
to
result.
the
roasted,
small
a
strength
same
the
ore
add
beaker
plant. It carefully,noting
of
the
appears
filtrate
consumption
no
well of
normal. coloration
left in
the
ore,
cyanide, and ferro-cyanide in of
Engineering
and
Mining
takes which
place will
there cause
may
lead
to
the
zinc
boxes.
Jowrnal,
and
a
are
still
soluble
some
somewhat
higher pounds precipitation of com-
Mineral
a
If,
on
Industry
addition
1898. ,
of
90
CYANIDE
THE
cyanide greenish
the
to
blue
roasted, and As
from
economy individual mills
stamp
cyanide.
for
will
made
be
There a
pay
of
foul." that
ores, are
fair
a becoming badly very oyanide, and
is
ore
high consumption
roasting
case.
which
a
soon
profitby
determined
be
must
oxidized
and
ores
direct
tailings with
treatment
be so low-grade that ing roasttailingsmay be out of the question, although if used would it would increase the extraction of the with gold on subsequent treatment cyanide There phuretted of heavy sulare cases by probably 10 per cent, or more. and where concentrates ores roasting interferes with the extraction of the a gold, and causes heavy consumption of very cyanide. The advisabilityof roasting ores previous to cyaniding should determined both in each be carefully by laboratory experiments case, and small where 1 10 roasted of dead to tons plant tests, ore
These
look
of
the
to
each
for
coloration, the formed, then
precipitate,is
may circulating solution
the
blue
filtrate, a
one
PROCESS.
could The
and
ores
worked.
be
features
main
of the
cyanide
for the
treatment
drying the ore ; dry-crushing mills ; roasting the in stamps, Griffin or other pulverized ore in furnaces; amalgamation in pans; cyaniding sands, if any, in and slimes in vats agitators ; filter-press by percolation separation final of slimes. and of solutions from slimes, washing of used A detailed at some description of the plant and process the leading Kalgoorlie mines will be found in Chapter IX. Goldfields In the Ohinemuri of New Zealand, the gold occurs and fine hitherto in dry-crushing and an state, extremely cyaniding have been used, the objection to wet-crushing being the were always difficultyexperienced in treating the slimes which high grade. mines with The Crown successful at the experiments conducted this last of the and wet-crushing subsequent adoption year, of
the
process
sulpho-tellurideores
used
process
at
the
Company's
The has
a
without
on
with
mill,
simultaneous
the
manipulation, carried
consist
have
shown
that,
with
is delivered
to
The the
ore ore
there
is
fed
solution
stock
careful be
can
cost.
following description of wet-crushing
special interest.* drying. With
with
slimes
the
of
treatment
little extra
very
in
cyanide the
into
of
about
solution
rock-breaker
the
mortars
'1
a
cyanide per The of the boxes. rate near strength, regulated by stop-cocks and 35 cwt. 2 tons flow is kept between hour, being gauged per As the stamps, which lbs. with at the supply-tanks. weigh 1000 constant
stream
*
of
a
Thorpe,
Auct.
Min.
Standard,
Jan.
19, 1899.
cent,
92
THE
in
the
is
reduced
a
third
20
the
slimes, to
to
half.
a
slimes
of
tons
original
of
amount
so
In
four
reduces
this
it
to
from
or
the
15
vat
quarter,
a
about
instance
particular
washes,
in
solution
gold
wash
on.
given
are
PROCESS.
second
A
and
eighth,
an
CYANIDE
20
to
tons
The of of water. extraction each, and cyanide solution one 90 few to exceptions being gold usually amounts cent., a per the the the due from of slimes to probably imperfect decanting which sand material of the some might easily vat, from coarser of
descend
method
The this
in
three
days
of a
four
the
of
lime,
(1)
are:
four
crushing
of
be
to
the
stamp
of
duty
The 15
labour
expense in
economy
off,
tons
per
boxes
is
slimes
vat,
each
and
five
gives
decant
with
the
day.
The
far
very
so
dry-crushing (2) ore;
over
drying
of
the
one
This
For
vat.
allows into
20
to
each
in
put
washes
from
the
(3)
;
"
days.
six
employed
There days. being during Sunday, up
This
vats.
the
in
Elimination
in
increase
three
in
-head
ten
"
are
rate
—
gold precipitating chief advantages of this method
The
good.
at
of
extraction
The
:
being hung sand the treating
for
half's
the
sand
with
being filled in washing, etc.
for
follows
as
stamps
there a
vats
days
half
aid
and
day
a
the
slimes
is
vat
one
available
are
the
treating
vat.
working
of
fills process sand vats, and
seven
from
slime
the
into
the
cyanide
of
consumption
;
mill In the of dust. filling; (5) absence and the review increased under from a one stamp duty has been half of tons to two tons day per stamp ; the consumption per formed decreased about The in half. cyanide "cyanides" by used the strength of the roasted in solution are absent, while ore is too weak the boxes loss by agitation. Crude to suffer much as of the appliances used the results in this some justify are process, be the expectation that dry-crushing with cyanidation will soon entirely displaced by wet-crushing with cyanide. mine At the Slime Process. at Sun-drying Try Fluke
(4) saving
of
Kuaotunu
in
broken
and
in
—
up,
slimes
of
part
New
the
Zealand, mixed
then to
two
but
only
can
in
the
This
sand.
of
dried
were
sands
with
parts
satisfactory results,
slimes
the
sun, of
proportion method gives
carried
be
in
in
on
a
one
very
dry
very
climate. This at
the
dry
running
plant,
is
mixed
solution
of
in
adequate
is in
process
Dexter
slime
0*20% an
slime
at
the
with
extraction
India, in
part
one
cyanide as
in
Tuscarora
at
top
use
fast has
as
been
it
the
in
sand to
runs
obtained.
five out
United
where
Nevada,
of
three
for
and
and
leached
days, at
one
the
the bottom
States
part
of
with solution until
a
CHAPTER
TREATMENT
With
low-grade
close
all
In
OF
and
of concentrates
treatment
is
'rather
the
oases
proportion of five to one. Pyritic concentrates may or simply by percolation,as give satisfactory results. Leaching
by agitation
with
cyanide,
ordinary tailings.
Both
methods
At
Watersrand
the
by cyanide
has
been
Goldfields
the
largely adopted
in
chlorination.
preference to the
From
with
—
of concentrates
treatment
leached
be
Percolation.
by
CONCENTRATES.
generally more advantageous to omit to ment. classifyprior to cyanide treatthe from best results obtained are cyanide the pyrites and exist sand in the when
it
ores,
concentration
VIII.
concentrated
the
storage leaching tanks, and
vats
solution, containing
from
subjected 0'4
to
per
cent,
twelve
is taken
material action
the
0*6
to
of per
the
cyanide cyanide,
strong of
cent,
to
In eighteen days. practice, solution is allowed to the slowly percolate through the concentrates, it is then and passed through the zinc precipitation boxes. the It is again made to allowed to original strength, and up This is until continued factory satisoperation percolate as before. a the Crown is obtained. Reef At extraction Cyanide
periods varying
for
Works
the
2000
of
per ton Mr. C. M.
method
of this
cost
17s.
from
P.
of treatment
is
said
not
to
exceed
lbs.
gives the following by percolation at
Wright
of concentrates
cyaniding
to
useful the
details
of
Choukpazat
the
gold
mines.* "
60 iron
The to
consist
concentrates
70
cent,
per
5
pyrites,
copyrite, and *
a
coarse
per very
Wright,
cent,
of
30
sands
:
Min.
40
of
the
of
consists
little altaite. Inst.
to
and
Of
cent,
franklinite, galena,
these
Met., London, 93
sulphides and than sulphurets, other
per
minerals
Nov.
the
20, 1902.
chal-
franklin-
94
CYANIDE
THE
PROCESS.
by far the richest, assaying from 7 oz. the galena holds practically no gold, and 18 about dwt. iron pyrites vary from per the value of the ore. general depending on After of treatment is simple. mode Our ite is
ton
ton
to
"
0*10 0*3
follows
wash,
water
per and
over,
0*3
the
days
comes
solution
strong
wash, "
vat
the
passes check careful
The
and
check
that
and
the
ment treat-
strength by
followed
by
final
a
water
percolation
the
same
is
taken
from
to
tailings
thrown
on
kept
constant
solution
and
exchanged
is
A
box.
zinc
solutions
of
solution
tonnage
zinc be
in
days;
24
zinc
cyanide and charged monthly, of
box
at
for
a
made
and
found
to
box
is
carefully packed at the left absolutely untouched
not
necessary
1,000-ton
eight compartment
is
complete
17
to
20
84
tons
wasteful
of
per
; this
This
zinc.
till the
and
ment treat-
it is
clean-up:
box,
zinc
the
of
commencement
each
;
cent.
mid-monthly
up
month
per
zinc
extraction,
was
was
and
the
are
through
passes
strong
consumption
treatment,
the
now
per
special sump
loaded
Usual
of
Formerly
cent.,
washes,
of strong
of the
upon
automatic.
duration
two
solution.
weak
cleaner "
and
somewhat
the
time
same
0*25
sump
of
kept
is
sump, the level
that
so
successive
solutions, catch
through cyanide used,
same
solution
weak
wash
and
solution
Every
per
for
of
turned
carefully
cent., when
per
more
cent,
washes
nine
are
until
0'26
to
or plain strength
required.
if
two
or
into
vat
0*07
solution
weak
two
vat
follow
complete. Two usually sump,
is considered of
down
then
;
ton,
per
oz.
(catch-sump
and of
contents
solutions
2
alkaline
an
wash
KCN)
cent.
the
:
cent,
per
effluent
solution
per
strength
cent,
per
a
0*12
to
cent,
weak
and
upwards chalcopyrite and
per the
an
ment compart-
is filled." Mr.
Wright
all the
concentrates, after
treated
12s.
wooden
the vats
shaft
derives and
The
became
into
10d., and
The
the
provided which
in the of copper presence immediately with that metal
cost
extraction —
are
with
the
to
coated
use.
concentrates
its motion
suitable
owing
by Agitation.
Leaching
steel
zinc
being put
was
Zealand,
that
states
At
84
the
in New
mine
fixed
is actuated from
by bevel-gearing, which, shaft intermediate by means
an
vertical
a
on
small
in
agitation
stirrers
in of
turn, a
belt
pulleys.
concentrates of the
have value
a
value
of
in silver
£30
for
£40
large sulphide (argentite). They
being with a thirty-sixhours agitated are of lime added Two pounds are cyanide. The The charge weighs 1£ tons. proportion
by
concentrates
cent.
per
Woodstock
treated
mechanical
of
ton
per
to
4 for
per
per
ton,
cent,
every actual
ton
a
solution of
recovery
of
trates. concen-
is said
to
and
labour The in where
and
90
from
vary
of
Zealand the
treatment
94
cent,
per
at
of
cost
a
18s.
for
ton
per
material.
leaching
New
to
95
CONCENTRATES.
OF
TREATMENT
at
results will
by
concentrates
were
be
the
Sylvia
mine
satisfactory.
very
found
agitation
in
the
next
by
Dr.
Scheidel
Details
chapter.
introduced
first
was
in of
the
1891,
plant
CHAPTER
IX.
LEACHING
The
first
scale,
for
by
Zealand
Gold
under
plant,
the
leaching
by
method
of
The
and
At
zinc
of
a
small
other
pyrites.
was
classified
in
pyramidal
cyanide slimes
said
is
94*59
classes
by
treatment
have
to
cent,
of
concentrates
for iron
A.
used,
and
in
Scheidel, 6
necessary
1891,
ft.
solution
cyanide
deep; tanks,
treatment.
occasionally
and
pyrites,
and
galena, Calif
10-stamp
a
Gold-
Thames
and
argentiferous
copper
battery,
ornian
concentrated
subsequently
in
buddies.
grades
were
The
agitation. amounted
the
of
per
the
with
in
four
of
concentrates
barrels,
or
seldom
diameter
in
appliances
boxes, and
contained
tubs,
mine,
Dr.
by
with
wet-crushed
slime-tables,
pany, Com-
Mines
were
Sylvia
ft.
zinc-blende,
of
It
The
years
favourite
tanks,
wooden
the
6
charged
heavily
was
proportion
jiggers,
and
Crown
the
agitators
erected
was
agitators,
and
sixteen
at
-filters, together
vacuum
ore
first
percolation.
to
plant
of
twenty-four
The
plant
three
extractors, The
given
agitation
consisting three
the
later
in
general
more
of
of
paddles.
concentration
an
operations In
McConnell.
works
plant
consisting
revolving being
the
the
cyanide
percolation
plant
with
preference
became
New
the
at
The
but
made
was
Glasgow,
feature,
prominent
a
extensive a
agitation
field,
formed
J.
ores,
1889.
in
Mr.
of
their
of
working
a
on
treatment.
new
fitted
from
Karangahake,
percolation
besides an
silver
process
Company,
supervision
agitation
cyanide
and
gold
mines,
AGITATION.
the
Extracting
Crown
were
of
recovery
Cassel
the
introduce
to
attempt the
BY
96
to
The
silver. amounted
to
afterwards
subjected
extraction '45
of
cent,
per
the
the
extraction
average
82*67
from
per
best
gold, from
of
cent,
the
to
and
all assay
value.* The to
1
of
strength per
cent., *
and
The
the the
Cyanide
solutions
cyanide time
of
Process,
agitation by 06
Dr.
A.
varied
from
from
six
Scheidel,
p.
0*5 to
79.
per
cent,
twenty-four
1
98
the
On the
the
of
nature a
causes
excessive
an
few
loss
There
tons.
acid
belief
and
from cases
that
prevalent agitation cyanide by decomposition by
a
of
; but
gas
exaggerated,
much
is
consumption
carbonic
atmospheric
PROCESS.
hand, agitation requires motive-power, and the be small, in no charges must process
other
exceeding
of
CYANIDE
THE
the
author
less than
certainly much
is
this
thinks
source
it
was
when early attempts at cyanide treatment agitation was from hours to prolonged thirty-six forty-eight continuously. author has that six to eight from The found, by many trials, of the gold in hours' agitation is sufficient to effect the dissolution the when reduced to sufficient degree of most refractory ores a in
the
fineness.
that
shown
The
the
of
rate
the
treatment
will
be
found
From
the
of
the
Director
the
in
:
it will
gold
was
of
mineralized Western
of the
different
sulphide
hour-periods,during is
ore,
given below,
be
that
seen
This
copper,
the
was
portion by Mr. Australia
School
extraction
complex
a
zinc, iron,
maximum
and
lead.
sulphide ore, An analysis
F. B. Allen, M.A., of
Mines,
the
gave
:
—
Insoluble
gangue,
.90*15 .
.
.
Copper pyrites, Iron pyrites,
4-40
Galena,
0-25
Zinc-blende,
0-26
Alumina,
0-13
Water
and
.
loss,
and
—
hours.
four
sulphides
the
at
Monowai
the
above
more
results
extraction
instructive
obtained
containing of
agitation have dissolved during
of
progress
first hour.
the
was
the
experiments during the greater portion of
Numerous
3-78
1-03
100-00
B.Sc, ing follow-
LEACHING
The
bullion
silver
14
for
oz.
leaching
by with
cent.,
per of
extraction
The
following with
"
was
Martha
metallurgist
per
amount
cent,
ore
and,
for
the
"
on
were
of
and
extracted
KCy
consumed.
per
supplied
ore,
by
a
0'45
to amount
the
on
zinc,
bullion.
the
of
showing 0*25
experiments
'per
cyanide
cent,
Mr.
by
Mining
"
used
was
large
very
deposited
instructive
0*33
Gold
cyanide
The
cent.
per
and
Martha
A
and
dwts.,
5
oz.
amounted
cent.
per
becoming
70
Waihi
of
precipitation
kindly
were
solution
1
consumption
92
the
interesting
0'25
Experiments metals
of
below
"
the
gold
were,
cent,
and
dissolved, in
ore
per
extraction
trouble
much
actual
0*6
agitation, an
was
copper
caused
A
ton.
per
this
of
contents
99
AGITATION.
BY
Company
rate
cent,
at
at
which
solution
tion agita-
solutions
G.
E.
by
on
Banks, Waihi
the
of
the
:
—
precious KCy,
and
CHAPTER
ZINC
X.
PRECIPITATION
AND
GOLD
The
this
as
bullion
for
zinc
form be
should
gives
free
advantage,
an
voltaic
gold
Zinc
on
zinc
in
from
the
In
and
it
is
of
zinc
a
by
turnings
in
has
It
lead
is
forming
therefore
a
tate precipi-
hours.
precipitated
advisable
and
is
the
the
moving
adding
more
replace
to
by
compartments,
will
twenty-four
been
compartments
upper
lower
the
85 the
per
The than
95
to
three
first
fresh
zinc
zinc
to
in
Zinc,
per
of
grains
form
the
that
afford
they and
dust
the
separate in
once
good
gold,
fact as
shown
be
"
that
should
but
flow
found
is that
precipitated
the
possess
applied
in
in
in
more
for
use
in
zinc
to
advantage
solutions
whereas collected
extractor-boxes, little
cipitation, pre-
likely
seems
precipitation,
charges
very
is
important
of
the
fequire
contain
not
neither
method
order,
working
principle
the
generally
will
zinc-fume,
former,
Furthermore,
vats.
periodical The
of
rate
drain
ton.
and
which
be
to
the
to
continuous
a
have
fume
gold
boxes,
zinc-dust
of
turnings,
zinc
the
leaving
particularly supersede
bullion
the
of
is
slowly
to
The
It
experience.
cent,
after
eight
or
precipitating
actual
allowed
is
boxes.
boxes.
solution, six
the
by
cent,
solution
cyanide
in
zinc
determined
soon
on
foot
bullion
of
the
the
practice,
through
the
weight. little
latter.
the
in
turnings,
least
precipitation
solution
of
tons
zinc,
pure
dissolved
forward
cubic
one
film
a
thread-like the
although
rapid
more
two
which
than
active
from
for
zinc.
rule,
general
a
the
in
antimony,
or
causes
the
with
pair
As
it
as
used
is
surface
most
arsenic
from
OF
SLIMES.
precipitation the
TREATMENT
attention
when at
except
clean-up." of
cyanide by
of
precipitation
the
2AuKCy2
has
a
stronger
following +
Zn
gold
equation ZnK2Cy4
=
100
by
metallic
affinity :
—
+
2 Au.
zinc for
zinc
is than
based for
ZINC
PRECIPITATION
By the above precipitate 6 oz.
AND
TREATMENT
it will
reaction
be
OF
GOLD
that
seen
1
101
SLIMES.
of
oz.
zinc
should
4 gold, but in practice it is found that from to 12 oz. of zinc are oz. required to precipitate 1 oz. of gold. The reactions which take at are place in the zinc precipitating boxes times varied and ment most perplexing, especially during the treatof pyritic tailingsor acid mineralised ores. Part doubt due of the zinc excessive of is no to consumption be ascertaineddecomposition by free cyanide, as may by testing the solution ing leavfor available after cyanide before entering and the zinc precipitating boxes the consumption and quent conse; but loss of cyanide by this cause is much less than generally and all insufficient in the for to account supposed, cases great of
of zinc.
waste
Zinc
soluble
in
solution
of
cyanide without In evolution of hydrogen. the extractors, the cyanide in contact that with extensive surface of zinc a comes a so large that metal but of into must solution, quantity curiously pass the of does free the in extractor not enough cyanide consumption correspond with the consumption of zinc, and we only concan clude that takes the in of extractor. a regeneration place process It is quite certain that the fouling of cyanide solutions with that troublesome alkaline takes inert substance, zinc-potassium-cyanide, the the solutions iii of place through the extractors. passage It might naturally be expected that would accumulate zinc in the cyanide solutions in to a detrimental extent, but this is found The zinc accumulate does not to practice not to be the case. all result in of the probability due to the action extent, a any the and in which contained its sulphides ore cyanide cause precipitationas a sulphide of zinc. The from electro-chemical precipitation of the gold, doubtless is always more rapid and complete from moderately strong causes, than from weak all circumstances cyanide solutions, but under very the solutions be alkaline must factory satisto ensure distinctly a precipitation. It has been chemists that this is due to suggested by some the nascent hydrogen, liberated by the action of the free KCy on zinc, taking the place of the gold, according to the following equations : is
an
aqueous
potassium
—
4
KCy
+
Zn
+
2H20
=
ZnK2Cy4
+
2KHO
H2
+
and 2
The any
free
liberated alkali
AuKCy2
+
H2
hydrocyanic present, and
=
2KCy acid
thus
2HCy
+
is
capable
there
would
+
Au2. of be
with
combining no
loss
of
the
102
CYANIDE
THE
combined
cyanogen
with
following equation
:
surface
in
the
NaHO
+
is
=
of
boxes,
NaCy
evolved
always
action
zinc
is shown
reaction
by
the
the is
+
H20.
when
gold
bubbles,
gas
indication
an
is
precipitated,
they rise to the satisfactory precipitation.
as
of
the satisfactory unpyritio tailings at Kuaotunu, of time the for a source some precipitation gold was trouble of much in charge of the to the chemists works, cyanide this difficulty but was overcome by making up the strength of the before solution to something like the entering the extractor original working strength. In trouble effected without extra by practice, this was any barrel solution of at a a cyanide simply placing containing strong the of the head allowing a steady drip into the extractor, and filled with which a cyanide solution, in the top compartment, was and filter of sand solution few a gravel. By testing the cyanide the of the it rate to times, required strength was drip bring up to determined. easily
During
The
the
This
gold.
—
HCy Hydrogen gas and the gentle
the
PROCESS.
author
cupriferous
of
treatment
used
this
the
from
ores
method
with
Monowai
in
success
mine
in
the
the
of
treatment
Gold-
Hauraki
fields,in 1895. It more
one.
the
was
found
rapidly In
order
that
from to
a
the weak
overcome
dissolved
solution
copper of
this, the
was
cyanide solutions
precipitatedmuch than were
from made
a
strong up
to
been has now original working strength. This method seded superby the lead acetate pickling process. In the of slimes and in filter-press treatment by decantation but formed large especially in the former, there are processes, volumes of excessively weak solutions cyanide containing gold. It was zinc precipitation matter of early cyanide experience that a such weak solutions from was imperfect, in fact far inferior very electrical to precipitation. The made for the that the lead-couple used soon discovery was precipitationof gold from solutions containing copper was also very the effective for extremely dilute precipitation of gold from and elsewhere Africa cyanide solutions, and the practice in South in slimes in a plants is to pickle the zinc, before trough use, until all 10 the solution lead of cent, containing a acetate, per black zinc is covered with a precipitation effected coating. The a by this lead-couple is almost perfect, only a trace of gold, as rule, finding its way into the sump. Bird At the Camp in the following page, a mines, as described
PRECIPITATION
ZINC
AND
zinc-mercury couple
is used
solutions
copper,
than
containing
TREATMENT
with
GOLD
OF
103
SLIMES.
for satisfactory results very is stated results to give better
and
the
lead-couple. It is the practice at some plants to allow a dilute solution of lead acetate into the head to of the zinc drip slowly extractors, the but is be to the of not account commended, practice on difficultyof regulating the rate of flow. Besides, by this method excessive
an
lead
of
amount
is certain
find
to
its way
the
into
bullion. It is
the
now
lead
sprinkle
practice when
the
the
cyanide
of
sulphides
contains
this
tank.
the
on By top the sulphide is decomposed, and cyanide sulphide by the precipitationof lead sulphide.
acetate
alkaline
When with
and
metallic
bright gradually a
coated
with
in the
is present
copper
coating,
encroaches
the
on
it
solution, which
soon
ones.
upper
from
the
covers
lower
When
the
in
begins
means
freed
the
to
the
zinc
boxes, zinc
is
the
precipitationof the gold is very slow and the imperfect. By increasing the strength of the solution to near the be boxes, the copper working strength, before it enters may in solution. largely kept the ore the When or supplies of fresh tailings contain copper, the zinc should when is passing only be added strong solution of the through the extractor. By attending to this much copper be kept in solution, with a can correspondingly satisfactory precipitation of the gold. It should, however, be forgotten that when there is much not the imperative to allow present in the ore, it becomes copper the gold with with the precipitationof the copper object of keeping the
the
keep becoming
10
turnings be placed in strength, they will per cent, lead.
of
effect
energy, the copper,
the
perfect
weak,
very
method of
in
mercury.
soon
useless
a
obtained
a
case
their
in for
gold
mills, Ouray value, and
weak The
this
acetate, of,
with
a
porous
electro-chemical
gold, and leave solutions, unprecipitated. means is, however, always
solution mercury
of
contain
which
mercuric
coated
Colorado,
in
much
tried without
mercury-couple
a
zinc, by
its
precipitationof by
lead
the
lead.
of poor was
of
covered
become
weakest
the
from
even
resulting bullion highly charged with Bird At the Camp
zinc
such
result
thus
solution
a
lead-coated
This
The
favour
and
copper
In
constant.
would
purposes.
will
acetate
with
zinc
coating
are
solutions
solutions
the
overcharged
extraction If the
in
copper
the
of
contents
copper
to
say,
copper,
zinc
some success
is obtained
cyanide is stated
the
solutions
waste
The copper. and abandoned
by immersing until to
it is coated
give
a
very
lead in the with fair
104
precipitation,while into
CYANIDE
THE
bullion
the
as
the
PROCESS.
is the
case
does
and
is recovered
mercury
not
pass
lead.
with
not are ores containing much Experience copper undue of the firstly,on account adapted for cyanide treatment, of the consumption of the cyanide ; and, secondly, on account difficultyof precipitating the gold in the presence of the base solutions the stock and metal by continued use, sump ; moreover, all useless for become charged with copper, and thus rendered of such as washing, or forming the basis practical purposes, working solutions. precipitate Occasionally an inert gritty, greyish-white, porous The the zinc in the precipitating boxes. of zinc cyanide forms on
shown
has
lead
which
reactions
that
its
to
have
formation
not
factorily satis-
been
yet
is be, its presence explained, but, whatever they may always accompanied by loss of cyanide and imperfect precipitation ment of the gold. This excepting in the treatprecipitateis seldom seen and of pyritic ores generally be prevented tailings. It can lime instead with by a careful preliminary washing, and treatment
soda.
of caustic
On
the
reduce thus
hand,
other
acidity,an prevent
when
free
too
a
of
incrustation
lime
will
satisfactory precipitation. there be, in the may
of
use
form
lime
is the
on
made zinc
to
and
pounds, organic comand excessive of hydrogen. an During injurious evolution Great the of the treatment pyritic tailings at decomposing the evolution of hydrogen gas Mercury Cyanide Works, Kuaotunu, was so vigorous that it lifted the zinc out of the precipitation On this occasion the boxes, forming a thick froth. precipitation the bullion of was imperfect and unsatisfactory, and suggested very polarization.
In
cases
some
When
a
forms
scum
the
on
presence
the
of
surface
of
solution
in
the
its cause should removed it and be precipitation boxes, both without delay. In the case of accumulated tailingsit will generally caused be of decomposing organic found to be by the presence the application of an a matter, and oxidizing agent often exerts
beneficial In
practice
solution thence
effect. the
box, and to
the
zinc
shavings
afterwards
strong.
In
are
first
transferred the
weak
placed to
and
the
in
the
medium,
medium
weak and
solution
precipitating boxes, the gold becomes plated on the zinc, and less than in the is destroyed The zinc solution the from strong. of extractor traces returned the to boxes, containing only gold, is if found its solution is made tanks, where, strength necessary, up addition of the cyanide. by weak The precipitationof the gold from solutions, especivery
106
CYANIDE
THE
PROCESS.
60
Borax, in
lure,
.
.
J. «/
.
r
„
i
.
.
•
solutions
same
solutions
would
actual
, ,
.
,
.
•
precipitation of gold by zinc, results cyanide of zinc and. potassium, and
double
the
.
.
.
oocia,
a
•
11*5
Sand,
The
•
cent.
per
would
lead
time
become
in it is
practice
found
the
to
this
the
in
that
belief
with
is not
the
of
formation
continual
the
charged
that
,,
use
of
the. working to
case
In
salts.
zinc
great
any
extent.
Feldtmann
potassic cyanide He
ores.
on
the
considers
that
the
where
be
may To
formed
prevent
suggested metallic alkaline contains avoid
the
salt
to
the
considerable
its
sulphides cyanide
of alkaline
quantities formed
zinc-
from
dissolving gold
of
action
by precipitatea portion
or
the
conditions,
of
zinc
of the
of
proportions
as
metallic
in
cyanide solution, sufficient alkaline sulphide the dissolved gold. precipitatea portion of
loss any addition of
in
this
of
excess
the
possible complications be determined required can
direction, Mr.
to
of form
practiceis
this
In
sulphides.
this
solution
a
is known
which
solutions, and
an
to
contain
ores
sulphides, soluble
capable
cyanide,
sulphides, serve insoluble sulphide. cases
favourable
small
metallic
In
to
itself
is of
in commercial
present
under
that,
states
in the
case,
lead,
or
insoluble when
general
however,
extractor.
in the
an
now
lead
soluble
some
other
it
would
salt, The
so
exact
Mc Arthur
S.
J.
other
sulphide in the cyanide advisable
be as
or
to
amount
prevent of salt
laboratory. The The or periodical clean-up takes place once Clean-up. twice The first operation is to pass of clean month. current a a the the water zinc to boxes, so as cyanide through remove is injurious to the often solution, which workmen, causing their covered with to become arms painful red boils. and The moved down then in trays holding the zinc are up the fine gold precipitates,and to allow their compartments as so fall the and settle in the sieve fine particlesof zinc, to through The of the box. of the trays are then contents bottom placed in false bottom easily removable a large trough, provided with an The zinc is gently teased and out of finely perforated iron. is partly tilled with clean in this trough, which rubbed water, much this in and as manner as possible of the adhering gold After all the has removed. is settled, as a slimy mass, gold The in the is syphoned off, the water remaining gold slimes sluiced extractor are through plugholes into the side launder, or and collected The in a trough. fine into the bottom compartment —
ZINC
slimes
PRECIPITATION
powdered alura to the solution. In the large cyanide works or filter-press
of
dried
discoloured
The
107
SLIMES.
addition
the
precipitates are
vacuum-filter.
returned
GOLD
OF
rapidly settled by
precipitatesare
or
TREATMENT
AND
zinc
in
the
shavings are being put in
the
to
small
a
precipitation boxes, fresh zinc The gold still remaining on the compartments. recovered at the next clean-up. The gold slimes are treated in one of three ways, namely
now
lower
By smelting with suitable By sulphuric acid method. By lead smelting method.
1. 2. 3
little
a
zinc
:
is
—
fluxes.
adherents. and still has many is the oldest smelting method loss of bullion. with attended is,however, laborious, slow, and It is gradually being superseded by the sulphuric acid method, lead which in its turn seems likely to be superseded by the smelting process. 1. Smelting Process:— Roasting the Precipitates. The dry The of air. precipitatesare roasted at a low heat, with free access object of the roasting is to oxidize the zinc in the slimes, and thus it to combine with the fluxes in the smelting, cause subsequent The
It
—
and
thereby
leave
the
Australia
In furnace
and
often
edges. light sheet-iron zinc The must
as
Zealand
of
over
is
possible. the roasting cyanide works plate, with raised large flat cast-iron fine
as
New
consists
It is built
the
bullion
a
small
a
placed
grate
the
over
and
furnace,
or
roasting place, so
as
a
to
hood
of
carry
off
fumes.
roasting
should
rise
above
never
be
conducted dull
a
red,
at
and
a
the
heat, i.e.,it
moderate
be
must
precipitates
action the surfaces fresh to continuously so as to expose of the the early part of the atmospheric During oxygen. white zinc oxide of are given off, but roasting, dense vapours and diminish the observed to as operation advances they are is complete. reaction the Time, finally to cease entirely when
stirred
from
to
one
Mr.
facilitated to
hours.
two
Feldtmann
10
per
slimes
by
the
found
addition He
cent. a
as
has
strong
of
that a
solution
little that
suggests
oxidation
the
the
zinc
drying,
so
as
is
cent,
per to
the
to
get
applied
be
it should
the 3
from
nitre, say
before
of
with the whole only mass. thoroughly mixed the oxidize assist the also said to subsequent zinc, but is helps to of ziucate the and with zinc a oxide, forming fluxing by uniting is not readily reduced so potash, which by the plumbago of the The
crucible dried
as
slimes
the in
oxide. a
At
powdered
many form
works ;
of
the course
nitre less
nitre
is added nitre
not
to must
the be
108
CYANIDEf
THE
used
than
any
free
oxidize is necessary to nitre remaining would
crucible
during
bullion
fine,
hastens
the
When
the
and
fusing
base
metal
present,
as
the
rapidly destroy
the
the
removing avoid
to
loss
plumbago rendering the slag and greatly
Besides cleaner
a
on
mixtures
precipitates, care
in the
have
—
—
Clean
Much
Precipitates
Little
Zinc.
Zinc
Very Sandy.
100
100
20
50
50
30
15
—
.
.
Soda,
of
and
Little Sand.
100
Precipitates,
of dust.
form
roasted Precipitates. The precipitates with iron mixed the a large, shallow tray, fused in plumbago The crucibles. following alway given satisfactoryresults :
fluxes, and
Bicarbonate
roasted
of bullion
Oxidized
placed
necessary
the
smelting process. roasting gives a
nitre
exercised
now
all
fusion.
Smelting are
the
stirring be
must
PROCESS.
6 50
Borax, Sand,
3
Fluor-spar, The
essentials
chief
corrosion. last
by
The
is conferred
that
the
avoid
necessarily so
dioxide
slag. that
in
loss due
of
is
now
Messrs.
basic
a
H.
E.
state
a
to
the
nitre
of
used
"
and
bulk, "
fused
of
non-
and
borax
—
it is
acid
an
the
W.
even
a
flux
used
the
charge.
slimes
are
be
must
metals
active
more
less available
The
the
slag. Manganese
Caldecott
A.
moisture,
flux
base
carrying
and
much
from
steam
hence
for
although following is the basis of proportions being varied, within required : it contains
free
non-corrosive
or
Johnson
be
through Acid-treated gold
character,
fusion
should
escape
Slimes.
produce a neutral generally added
to
as
the
by
fluxes
Acid-Treated
Smelting used
small fluidity,
are
sand.
the
to
as
slag
a
first
It is desirable so
in
into
have
the
shown
oxidizer
than
oxygen.* by
limits,
as
these
authors,
varying
the
conditions
—
Slimes, Fused
100
borax,
Manganese
20 .
soda
unnecessary. is found to assist should
be
made *
.
.
40 „
„
15 of
to Jour.
to
When
.
the
.
already
and
the Met.
:
a
few
best Soc.
40 „
„
sulphates fusion
ascertain Chem.
an
35 „
20
.
.
addition
to
.
.
dioxide,
Sand, The
parts.
....
are
basic
material
present,
a
was
preliminary trial proportions of the
S.A., July
1902.
sidered con-
little
spar fluor-
fusions
fluxes.
ZINC
The
PRECIPITATION
quoted
authors
bullion
AND
indicates
above little
too
dioxide
manganese much silver. in fusion
commercial
as
a
values
the
for
for in
this
or
silver,it
must
much
too
containing
one
dioxide
manganese
reason
fusion
in
smelting
be
used
slimes
with
clay-liners are Crosse
of these
charges. clay-lined crucibles
of silica aud
source
removable
with
crucibles
Plumbago used
silver,and
slag that
known
been
whilst
care,
all.
at
not
yields long
base-looking
or
dioxide,
109
SLIMES.
matte
a
manganese infusible an
has off
carries
containing or
It
that
state
GOLD
OF
TREATMENT
generally
silicate
uses
instead
of
soda
of
removable
clay -liners. In
works
where
have
slimes
large quantities of plumbago crucibles
be
to
smelted,
required. Fusion. crucible, previously annealed, is brick A flat placed on a resting on the bars of the furnace. this a placed in the crucible, and over priming of borax is then of precipitates are made charge of precipitates; fresh additions When the crucible is two-thirds subsides. 'as the charge fuses and fresh off and full, the slag is skimmed portions of precipitates Nos.
50, 60,
70
or
Actual
The
added
until
The
—
is
removed
now
be
bullion.
full of molten
it is three-fourths
crucible
will
The
from
furnace) and
the
the
contents
have which been poured into ingot moulds previously well and oil. All best olive the excess carefully oiled with should before be wiped out of the mould pouring the metal. hold constructed The be to two or melting furnace may crucibles
the
at
same
It
should
built
be
of
of
oil
three
the
best
is higher required to melt the slime mixture than that for ordinary smelting. Works At the Langlaagte Cyanide with the slimes, mixed the and 50 in melted fluxes, are charged into No. plumbago crucibles, which 22 crucibles furnace holds the hearth at a reverberatory The and time. time one required for melting varies from same of the half to three materials hours, according to the character a
materials,
and
the The
a
in
as
heat
of the
temperature
furnace.
slag resulting from the smelting of slimes always contains proportion of gold. It is,therefore, generally pulverized afterwards mill, and mated amalgasingle stamper, or in a small In is the it with sent to cases some smelting mercury.
small a
works
for
The
alloy
treatment.
ingots
re-melted
a
the
time.
heated
with
with
zinc, this
temperature
uniform
The
from bullion, obtained borax gold forms ; and, since of
bar
as
second
melting possible so as
should to
the
first
but be
obtain
a
smelting, are very imperfect
conducted an
at
as
low
approximately
of bullion.
zinc slimes
generallycontain
from
30
per
cent,
to
65
per
110
CYANIDE
THE
varies
fineness
bullion, the
of
cent,
600
from
to
PROCESS.
melting, generally
after
of which,
900.
clipsfor assaying should be taken from different parts of to obtain a so as sample for valuation, but representative reliable. the dip sample is always the most McBride gives the cost of smeltinggold slimes at 2d. per ounce of bullion, 817 of fine gold. At a clean-up giving 718 ounces follows : fine in gold,the costs were as The
the bar
—
£5
19
Refining by Sulphuric Acid.—
2. used
in
yet
been
The
acid treatment
in America
cyanide works
adopted
to
any
extent
8
2d. per
=
method
This
and
South
in
Australia
fine
oz.
is
commonly has
Africa,but
not
Zealand.
New
or
gold.
of the
is a simple enough operaprecipitates tion, and was u sed occasionally by the author for the refiningof parcels. The necessary apparatus consists of shallow wooden
small
tubs,
vats.
or
operationis conducted as follows : Clean water is passed all traces of time, to remove through the zinc extractor, for some The then from the boxes and removed are cyanide. precipitates placed in the first vat, with a sufficient quantity of dilute sulphuricacid. The acid should not be too strong, nor yet too weak ; a mixture consistingof ten parts of water and one part of The
—
strong acid The zinc six
well.
answers
dilute
quantity of
present
in the
of the
parts
required; and
acid
will
depend
precipitates.With
acid with
mixture
to
zincy
very
one
the
on
50
per of the
cent,
proportion of of
zinc,about
will precipitates
from precipitates,
ten
to
be
twelve
parts. The
allowed
to
hydrogen When the
clear
tub,
and
this means
L
in
mass
the
settle.
should
tub Heat
is
be
stirred occasionally, and then generated, and large quantities of
gas liberated by the action of the acid on the zinc. the undissolved have been allowed to settle, precipitates
liquidshould thence
any
be
removed
after finally,
fine
an
of particles
by
decantation
interval,into bullion which
a
have
into
third
a
second
tub.
escaped in
By the
ZINC
decantation
first which as
PRECIPITATION
has
will
a
bullion
water,
to
Then
vacuum-filter.
the
with
mix
of
amount
crucible
As
the
until
added,
be To
permit
time
to
the
protect described
The
crucible
in
the
the
is used from
over
slag
preceding generally be
in the
any
free
acid
melted
of
metal.
skimmed
be
can
flux
it will
by
off from
can
be
to
necessary
using a clay-liner the heading devoted
under
pages
as
to
Slimes."
from
850
900
to
fine, but
with
a
little
worked
bullion, and, properly conducted,
method
hot
and
up to 950. suitable appliances, this process possesses It occupies less the smelting process.
With
When
clean
and
full
parts
corrosion
of acid-treated is
trouble
finer
with
glass, according to fuse in a plumbago has already been placed. should portions of bullion
is three
done
being
crucible
bullion
extra
tubs
found
be
the dry on an oxidizing roasting on a oxidize base sulphates any
priming of borax and subsides, fresh
dioxide
Smelting
"
to
so,
will
that
time.
If manganese
the
to
and
;
of borax cent, per still present, and
oxide
the
the
Ill
SLIMES.
tub
slimes
a
this
of
10
second
sulphates bullion
or
GOLD
decantation
in
soluble
hour
or
zinc
fuses
charge
washed
the
an
5
which
in
be
dry, subject
for
pan,
the
second tub.
remove
When
iron
present. Next,
the
base
OF
in
third
now
all
remove
remaining. shallow
in the
should
TREATMENT
secured
be
escaped during
fine sediment
The
AND
quantities of
large of settlingthe
time, produces
less.
costs
precipitateshave and
slimes
tages advan-
many
be
to
is too
dealt slow
with, the and
decanting sive. expenof the slimes from the acid separation case, be effected in a solution, as well as the subsequent washings, must and South vacuum-filter, or a filter-press, as practised in America In
the
this
Africa. The feet
filter used
for
the
is
purpose It is provided with
wooden
a
box,
two
or
three
filter
webbing, or cloth, of fine twill duck, resting on and fixed with canvas or a grating of wood, for washing. slipsof wood, so as to be easily detached false bottom, below The the webbing, must be 15 20 in. in. or and with solution the limb of which a deep, provided gauge, upper should the be air-exhaust 2 in. below connected with the pipe square.
vacuum
Care
a
boiler. must
be
taken
to
draw
off
they rise by a plug-hole before which is placed immediately pipe, When
the
acid
solution
webbing lasts does the washing filter-press filtering,the
the to
acid
the
before
is diluted for well
to
several
and
solution
level the half
of
and
the
washings air-exhaust
filter -frame. its
strength before operations. A Johnston
expeditiously.
112
Acid
Treatment
abstract
an
CYANIDE
THE
of
South
in
a
Africa.
read
paper
PROCESS.
by
E.
The
—
H.
following descriptionis
Johnson
the
before
and
Chemical
describes
It
the Africa. Metallurgical Society of South the slimes Works, where are employed at the Princess process will be submitted before and to acid treatment especially smelting, results and for its of costs : metallurgical interesting figures —
At
the
separated
Princess
Works
the
from
A
vacuum-filter.
the
solution
slimes
drawn
from
off
the
zinc
by
the
until
the
them
with
boxes
are
aid
of
slimes
passed through are cyanide. weight of the slimes, including gross slime of moist moisture, is then taken, by weighing the buckets to a large sheet-iron during transference tray placed alongside the acid tank, to determine to the amount of sulphuric acid necessary destroy the zinc. the approximate weight of slimes treated, to be Having found sufficient acid vat addition is run the the to water into form, on of the acid, a 10 per cent, One solution. pound of acid for every This would be equivalent pound of moist slime gives good results. acid is 1 J lb. of acid to the to about pound of slimes, dry. The then the closed down vat added, and tightly. The is stirring apparatus kept continually moving during the fed time of feeding in the in gradually in the slimes, which are taken It is in which from the filter-vat. condition same they were beneficial to keep up a continual stirringfor at least half an hour has apparently ceased. after the action into After all the slimes in the acid, a jet of water is turned are down wash the hopper adherent to slimes, and everything any that has used the been in the of boxes, etc., is well cleaning-up filled washed in the The is then vat same jet during removal. a
free
with
water
The
and
litmus
allowed
with within
vat
acid,
more
is done
middle
paper
and
vat, and
heating, a perfect settlement heating with a steam jet,
difficult.
repeatedly with —
not
When
by syphoning
usually at each refillingby means being given to the water. to
settle.
hour.
an
much
was
to
dilute
washing
fillingthe
is
The
Working takes place settlement
wash
water
from
water,
four of
or a
long
This
reduces
five
until
the the
clear
liquor, and
solution
is neutral
washings. It is well paddle, a rotary
wooden
causes
the
off
risk
the
slimes
to
stirred motion
collect in the
of loss
during syphoning A sample of the washings at the side. syphon being let down taken continually during syphoning off showed, on careful assay of solution. of a large sample, 13 gr. of gold per ton The on drying of the resultant gold slime is conducted an open enamelled hearth cast-iron dishes. The in cakes are large drying and broken transferred small sheet-iron to subsequently trays up the
of the
—
114
allowed
settling is
for houi*s
twelve
to
PROCESS.
CYANIDE
THE
hour.
one
first
the
remove
washes,
two
from
it takes
Usually
the
as
eight do
slimes
to
not
readily in the heavy acid liquid. is All the washings are stored in a large settling-tank,which The cleaned at settling-tank, after a year's long intervals. up £20. yielded bullion worth run, settle
so
"
The
"
first two
10
from
20
to
wash
three
or
cents
found
are assay washes subsequent
but
ton,
per
waters
on
yield
to
from
contain
only apparent on assay of large evaporations. then and The are gold slimes are partiallydried by filter-press, The and calcined. hearth transferred to a calcining furnace 5 cents
to
trace,
a
—
"
and
safe
a
"From
into mixed
parts:
the
and
The
feet.
square
furnace
purpose
required, and graphite crucibles, and smelted, having been viously preof the following of a flux composed 50 per cent, with slimes
the
furnace
removed
are
as
—
2
Soda,
parts.
....
Sand,
1*5
Borax
4
„
powder, Sulphur,
.
.
„
required.
as
....
Thus
require frequent skimming
with
lbs. of
100
slimes
lbs. of
200
smelted
in from
flux.
ten
The
sixteen
to
charge hours
is
for
crucible.
each
slimes
The
"
contain
considerable
a
little zinc, we
double
the
serves
furnace-doors
calciner.
the
charged
of 36
area
an
securely padlocked,
are
of
has
of furnace
hearth
instead
use
consequently certain quantity
a
the
readily converts bullion
comparatively
usually
from
found
to
15
to
contain,
on
25
assay
.
Copper,
.
Zinc,
...
Gold,
contains
Copper, Zinc,
flowers
oz.
.
.
of
per
ton.
»»
.
.
.
60% 3%
.
the
from
bullion
melting
is
ruby
red
—
oz.
)
Assayed
J
shots
.
265
Silver,
sulphur, which matte or regulus, leaving the is by the way regulus, which the weight of the bullion, was of
—
15 .
no
or
but comof copper, paratively is used ; but nitre
408*0
slag resulting and
of
little
23*4 .
Silver,
colour,
a
The
cent,
per
Gold,
"The
to
copper fine.
quantity
.
„
6 to .
.
.
.
12 „
8% 16%
without or
removing prillsof bullion.
in
800 about to averages with zinc. little a entirely copper
almost A
sent
shipment
to
the
made
first
Mines,
netted
850
of
use
Mr.
by
it has
been
P.
fine,
regulus
Method.
S. Tavener
the
impurity
mixed
lately
was
This
—
process 1899.
in
August operation at the and already the process The at Johannesburg.
in continuous
Limited, Johannesburg,
115
SLIMES.
£120."
us
Lead-Smelting
1901
August
slag and
lbs. of
and
smelter
Tavener
3.
3000
of
GOLD
OF
bullion
"The
"
TREATMENT
AND
PRECIPITATION
ZINC
was
Since
Bonanza been
has
adopted by many leading mines adoption notable in of the marks advance lead-smelting of gold slimes a old is laborious, and smelting process cyanide practice*. The losses where entail serious of gold large quantities always likely to have the of slimes is to be handled, while sulphuric acid method slow, and costly. cumbersome, The obvious with the advantages of lead-smelting compared be brieflysummarized follows as sulphuric acid process may : —
Saving of cost per oz. of fine gold produced. b. No by-products. Less liabilityto loss in handling slimes. c. d. More gold actually produced from a given weight a.
of slimes.
metallurgical process is its cost, and judged marked a advantage. In by this principle,lead-smelting possesses where the acid method South has, perhaps, its Africa, sulphuric the to cost, according Tavener, is not greatest application, average less than The leadshilling per oz. of fine gold produced. one smelting process costs threepence per oz. of fine gold, including all a means charges, which saving of ninepence per oz. compared with sulphuric acid method. Thus the lead method at threepence per oz., in a mine producing month fine from 2500 would effect a works, cyanide oz. gold per saving of costs amounting to £93, 15s. per month, equal to about The
£1000
a
The
of every
essence
year.
lead-smelting process
Tavener
and
other
with
is
cheap, rapid, and
with
some compared processes, be is to universally adopted. likely practice The following working details of lead-smelting
the
Bonanza
before
the
mine
are
Chemical
extracted and
from
a
efficient
modifications
read
paper
Metallurgical Society
in
as
practised
by
Mr.
of South
at
Tavener
Africa
last
October.* Mr.
comparing for
the
he that says it to a scorification
Tavener
that
reason
*
Jour.
the Chem.
zinc and
best
can
assay
slimes Met.
Soc.
describe
lead-smelting by
conducted are
on
melted
S.A., Oct.
1902.
a
large scale, the gold
and
116
THE
recovered to
use
in lead better
a
"The way,
with
from
the
side for
the
cakes
'
the
sufficient
fine
into
the
the
is then
'
zinc
half
to
'
tub
in
trays
into
allowed
to
get
the
holes
the "
to
to
zinc the
on
all
When
also to have
of
the
the
with
been the
slime
and
out
keep
one
ready the
there
both
oven,
and
minutes the
for
fine
zinc
should
account
they
in the
slime
in
is first dealt
with.
After
rubbed
through a sieve, roughly weighed for fluxing, previously mixed. fluxes and passed through a sieve at
once
then
It is then mixing. the filter-press slime
with
is dealt
top
having
is mixed
thorough
furnace.
inch, and
linear
fluxes
necessary slime The
ensure
fine
the
on
up is then
and
fifteen
to
which
mixed.
furnace, the charging warming in the drying oven, it is four
pumped zinc
drying
a
no
ordinary
once
fine
cleaned
through,
warm
the
furnace, and
to the
Care is taken tray being sufficient. slime, and on separate from the filter-press
"In
cupelled, or
heaped
hour,
an
each
be
is
is filter-press
put
are
in
precipitateis at
clean-up
condition
moist
conducted
filter-press.The
for about
is allowed
time
bullion
"is
all the
The
room.
in their
and
lead
that
of
drain
to
smelting
taken
slimes
bottom
allowed
and
The
up,'"he continues,
exception clean-up tub
at
PROCESS.
refined.
the
i
remains
bullion.
term,
clean
*
CYANIDE
same
order
way, to
shovelled
direct
is fluxed and
put
and into
loss
prevent
into
charged, the
the the
furnace
by dusting, and
litharge present on the top commercial residue assay slag and are unless used for in this manner nothing,
greater portion
of
of
charge. The fluxes used costs litharge. The former be thrown it would away." 1 have the found that question of fluxes,he says : Discussing the following, with little variation, will give satisfactory fusion and clean slag : Slag, 25 to 30 per cent., made up of 10 per cent, old slag and scalings slag ; the balance, equal quantities of assay In the event the pots of previous smelt. of the lead-smelting from like here the advantage method to point out being adopted, I should from crucible of storing the slag now being obtained smelting, converted its gold contents into bullion since in the lead process are have If it were not free of cost. to be treated, clean slag would I have last been able the with deal several to used. During year material fine per ton, left this of tons fiftyounces assaying over after the Boer the mine behind applies occupation. The same on and else termed liners to gold, now anything carrying product byclay the word With a lead-smelting furnace by-product is the
"
—
—
forgotten,
since
none
is obtained."
quantity of litharge to be used will depend on (a) value slimes, (b) weight of charge in furnace, and (c)the percentage gold required in the resultant lead bullion. The
of of
ZINC
Mr.
Tavener
slimes
:
gives the
OF
TREATMENT
AND
PRECIPITATION
following proportions
gold
for
of fluxes
—
slimes, Litharge, Assay slag, Slag previously used, .
.
parts by weight.
100
Gold
.
60 „
...
.
Sand
(Si02),
fine
zinc
Fine
10
to
15
5 to
10
„
„
.
1%
.
following proportions
.
of
weight
of
:
litharge.
—
parts by weight.
100
zine,
Litharge, Slag,
15 „
.
the
uses
to
.
.
.
he
10
.
.
Sawdust, For
117
SLIMES.
GOLD
.
150 .
.
.
„
20 ....
„
the and will necessarilyvary, products of different mines mined easily be deterslag can proportions to give a clean, well-oxidized crucible tests. scale with by experiment on a small assay that Mr. Tavener, considerably less assay, or however, mentions than other will effect fusion in a a good slag, reverberating furnace The
in
a
crucible, and
cent,
less
slag
The
should
cent,
the
at
quantity reduce
success.
is added
litharge
on
has
with
be
to
30
use
than
per found
was
8
of
cent,
per
gold, make
preferable in gold contents. to
10
or a
lead per
larger
rich
it too the
the
proportioned that
so
found
was
have
to
is used
safe
reverberatory
than
more
It
maximum.
sufficient
ensure
carry
than
be
trial.
litharge should
not
reducer
No
in the
smelting
of
of lead
it would
that
states
crucible
quantity
bullion
of
when
in the
necessary
he
fine
is relied
which
zinc,
to
on
litharge in the slag to With the gold slimes dust charge, 1 per cent, of sawthe weight of litharge,but if a larger proportion lead, leaving
been
used,
an
then
of
excess
1£
from
2
to
per
cent,
of sawdust
is necessary. The
furnace
"When is banked
the
up possibilityof
work entire from
is described
charge the
follows
as
of zinc
sides
to
and
the
:
—
slime centre
is in the so
as
to
furnace, avoid
it
the
slag level as charge litharge is covering the surface, and this again a light covering of easily spread over on fusible furnace is charged the slag is spread. The day previous to of the fire smelting, and one lights a slow night-shift men about 3 At which 5 to serves a.m. dry the charge. a.m., the half hour in damper is opened and the fire urged, and an the furnace is at a smelting heat. the 9 10 a.m. or By charge is reduced, then sweepings from cyanide works, smelting room, or the
particles remaining reduces
and
settles
on
the
down.
sides A
above
the of
118
CYANIDE
THE
PROCESS.
slag requiring re-smelting,is added
any the
molten
the
slag become
is thrown is
bath.
When
fluid,it is well
in to reduce
repeated
all this
until
the
has
and been
stirred
excess
of
with
is
quickly absorbed
fed in and a
in
melted, and
rabble, and
litharge in slag.
This
sawdust tion opera-
the
remains the rabble when slag, which on withdrawn from the to be furnace, is judged by its appearance olean. The is off into the slag now run pots through slag-door, the
level
bath
of
of
which
12,000
is 4 in.
of lead
above
bullion
the almost
centre
of the
lead
this
bath
—
a
occupies space. about slag-door is built up 12 in. cast-iron in fireclay, plates,£ in. thick, bedded of and in front of bank these of one on another, top plates a In the order to fire-clayis also made. run slag off,all that is is to break this bank, plate by plate, and allow so necessary away the into the the slag to flow over pot. When pot is full it is and wheeled is put in its place. The another filled pot is away after and minute is run outside, standing a or two, tapped, and the molten the ground to cool ; that out slag allowed to run on which remains the sides and the bottom of pot is brought back on for further When no use. more slag will flow from the furnaces the bath down level of the to the owing to being slag-door,it is off by rabbling. At first sight it would waved difficult to appear draw this remaining slag off without lead, but dragging out some little practice enables it to be done a very closely that there is so little but a thin In the of a event skimming of slag remaining. little lead being pulled out into the pot, it is recovered from slag It is for this that the about in. 2 reason pots. tapped pots are the bottom. from By opening the fire door this last skim on the lead bath A shovelful of lime is thrown in to quickly thickens. This assist. skim is easilypulled off,and of course is held over until next clean smelt. surface of lead is exposed, a By this means and zinc would rid be of, for at this stage quickly got present any the lead is at a bright red of air due the free access to heat, and the open fire door quickly oxidizes it. So far, lead recovered by this method has always been and clean soft, a proof that no zinc could be present, since of zinc cent, one gives lead a distinct per makes be rolled. The and it that it hard cannot silvery colour, so lead bullion is tapped by driving a \ in. steel bar, tapered to a is closed with a point, into the tap-hole,which fire-clayplug. The into it to the lead is run iron moulds an trough, which conveys the floor." placed together on the Before the is well lead-bath furnace stirred,and a tapping sample is taken out with a ladle and granulated. The described, cupelling or refining of the lead bullion is next with the making of the useful hints on particular details and some "Before
oz.
fillingthe by placing flat
furnace,
the
ZINC
PRECIPITATION
bone-ash
details
minor be
not
and
test
The
AND
regulation
from
the
specializedin costs
smelting
the
at
for
TREATMENT
this
of
operation
Bonanza,
Limited,
for
loss
12% 1832
£20,
estimated
output
in
It is claimed
1
lbs.,say
were
need
cupelling
as
follows
10
7
=
lbs.
=
ton
at 0
0
=
373d.
10
7
=
2-837d.
20
period, 12,810
the
than
for
.
that
in
and
:
—
2-463d.
at
£151 Gold
only
and lead-refining,
(June-Sept. 1902)
15,269
on
differs
process
stores
£131 Lead
119
SLIMES.
work.
months
four
The
of blast.
usual
GOLD
OF
oz.,
lead-smelting acid method,
fine. recovers
and
this
followed
the
a
of
gold justified identical gold
larger amount
claim
be
sulphuric seems large experiments on equal weights of slimes In six trials the lead 10*5 by both processes. gave process results than the acid treatment. These higher recovery per cent, much could than be in continuous obtained are probably higher evident but that it is if only one two more working ; or per cent, be the recovered, the lead-process has fully established gold can by
to
several
claims In
of
Mr.
Tavener.
reading of Mr. Tavener's suggested that the probable loss of gold paper, Mr. D. J. Williams of such by volatilization in the cupellation,caused by the presence volatile metal zinc, might be avoided a as by first dissolving the jecting zinc-gold slimes in sulphuric acid, washing, drying, and then subwith Tavener this proposed Mr. to lead-smelting. agreed rather stated that he receive the furnace would at and modification, and easier the acid-treated would render work precipitate,which the
discussion
less troublesome.
which
He
further
stated
that
with
zinc
present,
a
120
PROCESS.
CYANIDE
THE
required, while with experience and skill was material needed.* acid-treated little or no experience was That lead-smelting recovers a higher percentage of gold than certain
the
of
amount
acid-treatment
it is not
evidence, but
recovered;
thus
quite
that
is, to
established
be
to
seems
to
easy
so
show
pretty conclusive
on
point
the
to
the
loss
method
of
where
of
source
takes
gold
place
in
acid-treatment.
Zinc
Precipitation.
Dust
agitate cyanide
certain
a
decant
the
of
in
allow
During the adopted
be
mentioned
the
Montana
past year at
of
or
method
this
two
of American
number
a
Homestake
the
Company,
vats,
application is to the with dust gold-containing the precipitate to settle, and
solution.
clear
been
the
quantity
solution
The
—
Company,
Nevada
; and
the
precipitation has which
mills, among
Mining
Mining
of
Company,
Montana
De
; the
Consolidated
may Dakota ;
South
La
Mercur
Mar
Mining Company, of
Utah. At
the
carried
Company's
Homestake
cyanide
works
u
Precipitation is
dust of zinc in five tanks 25 ft. in diameter by means and 20 ft. deep, built of California The red-wood. bottoms are inclined is provided in order to to one side, where a small sump No drain the tanks gold storage solution tanks are used, perfectly. the solutions from the leaching vats directly into the draining The out precipitating vats. are pumped precipitation vats by the solution to filter made duplex Prescott going pumps, presses in the Homestake shops. The pulp treated by the mill is of a highly siliceous nature, often however hornblende, carrying some the sulphides being mainly pyrite and The extraction pyrrhotite made is in the of 90 cost neighbourhood cent., the being per between and 45 50 of material cents ton treated, probably per the latter figure."! nearer In America the 25s. to 29s. per price of zinc dust varies from the of dust used amount for precipitation varies from cwt., and 6
on
9
to
oz.
Charcoal
Precipitation.—
charcoal
solutions.
packed The
use
process in
handled
*
is
being
The
with
charcoal
The
of solution.
ton
per
toria cyanide plants in Victhe to precipitate gold from cyanide is passed through series barrels of a the gold is deposited. charcoal, on which
solution
finely broken is afterwards is too
burnt
and
slow
where
Jour.
Chem.
and
Fulton,
The
Met.
many
to
cumbersome
large plants in the twenty-four hours.
t C. H.
At
used
hundreds
an
ash, to
of tons
and
the
recommend of solution
S.A., Jan. 1903. Engineering and Mining Journal,
ash
fluxed.
itself have
to
Soc.
June
4, 1902.
for be
122
THE
CYANIDE
PROCESS.
Hours.
Filling vats, wash, if necessary, Preliminary alkali or water Strong solution, 0'2% to 0'4% solution, £ to J ore
12 12 .
of
—
In
with
contact
12
tailings,
.
.
.
Percolating, Dry or air- leaching,
12 4
solution, 0-15%
Weak
of ore,
to
0*2% solution,
\ 12
........
air-leaching, weak cyanide washes, 0*05%
Dry
about
4
or
Two
Two
\
about
each
clean
to
0*1% washes, 12
of ore, each
washes,
water
£
about
12
of ore,
.
8
Discharging vat,
100
Total,
...
quantity of solution used, including the water washes, is about The equal to the weight of the ore. quantity of strong varies used solution according as a preliminary washing with a it is dilute solution has been In the former case employed or not. about 25 per cent, of the weight of the ore, and in the latter case The
about
total
40
The
cent.
per
percolation vats top, and
of the
inches
solution covered.
allowed
then
is
The
the
penetrate
of the
vat
settle
shrinkage depending on the depth of moisture in the tailings. value of the The tailingsvaries from
of of
the
actual
varying
extraction
from
4s.
amounts
10s.
to
70
to
The
inches,
some
the
and
vat
12s.
20s.
to
75
or
they
the
the
are
amount
ton, and
per
the
to
few
percentage
at
cent.,
per
a
cyanide
strong
tailings until
ton, according
per
within
tailingsto
is levelled.
surface to
contents
with
charged
are
their
size
cost
a
of
the
plant. The the
Deep
Jumpers
newest
the
on
Hand,
up-to-date practice. their
African in the
next
described
*
The
works
Mr.
John
the
works
of the
modelled
are
be
Yates
and
as
unnecessary
practice, in
slime
represent
cyanide
and
and
the
experience ;
it will
African
and
Waikino
and
pages,
by engineering on The
at
practice
South
of
mill
new
cyanide plant
his
recent
works
Waihi
they all
give of
South
latest
further
which on
details
lucidly metallurgical are
Rand.*
Yates, " Present Day Metallurgical Engineering Mining Journal, London.
John
at
fully described
are
work
and
Company
the
on
among
advanced
most
to
are
on
the
Rand/'
1898,
OF
APPLICATION
New of
gives 2
and
"direct
the slime
or
deep.
Of
6
The
9
and
each
from
battery the
is
it is
is saved
filled cent,
per
resulting The
the
when
the as
the
are
of per
the
of
fine cent,
per
which
pulp
are
viously pre-
another
vat,
the
that
so
race,
the 200
but
small
a
days,
of
275
and
of
tons
the
ores.
alkaline,
the
top,
of
of
course
used
cyanide
soon
solution
The
solution.
in
treatment
of its
during
water, acid
As
strengths
cyanide
amount
of free
pyritic
receiving
vat
the
neutralize
Various
each
drained
being
slightly
is
away
the
of
foot
1
vat.
decomposition
vat, to
within
to
after to
is commenced.
length is
6
lbs.
tailings.
following
table
works
the
*
vat,
solution
the
by
is six
treatment
The in
Each
draining
into
of
from
remaining
contain
vat
another
into
alkaline
formed
from
ton
is diverted
solution
treatment
the
15
filling the slimes
the
tailings (sand)
with
an
solution
pumped
in
the
the
launder,
a
quantity
vats, of
into
—
with
by cyanide
treatment
treated
be
to
and
solutions
slimes
About
away.
worked
into The
a
race.
leaving
after
a
is
solution,
of
pumps
wheel
whereby
and
slimes
strong
or
ft.
6
vat
tons
tailings,
course
overflows
Treatment.
of
tailings
the
636
separators.
flow
the
In
each
the
9
spitz-
capacity,
of
into
and
and
top
tons
top
of
separators,
into
water.
stream
is treated
the
ordinary
200
of
consists
says,
the
at
tailings
second,
tailings
the
medium,
a
would
of
centrifugal
slime
the
in
slimes
is filled
Method
of
he
of
the
or
Pengilly
slimes.
of
vat
pulp
the
launders
tailings
proportion
The
otherwise
with of
weak,
into
eliminated
are
the
well
boxes,
of
are
Card
extraction
square
three
means
to
pass
that
through
run
10
conveyed
separator
slimes
by
4
Institution
the
treatment
capacity
the
vats.
is lifted
plates,
first
sand of
treatment
which
a
pumps
F.
overflow
total
with
that
Mr.
are
13
the
away
have
before
Around
each.
connected
motor
ft.
vats,
carries
tanks
is
the
to
style,
capacity
solution
vats,
6
read
plant,
separators
treatment
which
a
by
19
tons
launder,
on
the
slime box
pointed
130
of
The
123
COUNTRIES.
successful
the
of
treatment
The
tanks.
kasten
London,*
details
19
DIFFERENT
paper
a
filling process."
separators,
solution
In —
Metallurgy,
interesting
some
IN
PROCESS
Mine.
Kleinfontein
Mining
by
THE
Trans.
in
Inst.
shows
the
treatment
Min.
and
method
exact
of
Met.
a
vat
London,
of
of
procedure
tailings vol.
vi.
p.
:
—
113,
1898.
adopted
124
Vat
I.
Amount
PROCESS.
CYANIDE
THE
Charge
of
KCy
I.
Capacity
used,
5*9
207
lbs. per
Tons.
ton.
OF
APPLICATION
PROCESS
THE
125
COUNTRIES.
DIFFERENT
IN
The in the Extractor Boxes. tion precipitaPrecipitation of Gold is the of gold from treatment vats the solution coming from A certain of zinc shavings. effected,he says, by the means portion of the ore the mine is of rebellious from a nature, containing coming sufficient metals if not to retard, foreign prevent, the precipitation of gold by zinc. To counteract the effects of these foreign metals, it has been proved efficient in practice on these fields to set up a lead couple, and this is effected by dipping the zinc at these works weak solution of of lead, preparatory to being acetate shavings in a the in boxes. extractor placed In all cases that zinc containing from 1 to 2 per cent, it is found of lead gives the most satisfactoryprecipitation. By the use of of lead acetate a only perfect precipitation is brought about; after passing through the of gold remaining in the solution traces —
boxes.
extractor
The
actual
working costs amount general charges and maintenance. has
It with
been
shown
classes
certain
of
advantageous
more
treatment.
crushing White
the
at
has
country
nevertheless
favour,
certain
the
Western
local
Australia
conditions,
never
made
Wei
Estate
be
it may
to
preparatory
Dry-
with Mr.
by
mine
that
universal.
viewed
been
experiments
Luipaards
ton, including
per
wet-crush dry-crush than Africa wet-crushing is
to
that
in
and
ore
South
In
and
America
in
Is. lid.
to
much
Franklin
interesting and
are
instructive.*
8
few
days
double
the
in the
placed and
away,
steel,
close
the
to
and
bottom
Mr.
and
The
ore
in
mine
the
lower,
does
in
a
treated
was
to
White
and
discharge
mill
transferred
then
obtained.
thus
and
bottoms
diameter
ft. in
25
little below.
a
tanks
upper
being
treatment
of
filter
usual were
distance
some
made
were
tanks
Three
doors.
a
with
deep,
ft.
row
used
tanks
The
not
a
sider con-
advantage dealing drymixed the in first instance, material, as properly ore of air entangled in the is He is abundance and there dry sand. is transferred the damp rather of the opinion that when to the ore is a tendency to pack closer and of tanks, there second to row double
treatment
added
was
to
varying thoroughly mixed broken
the
in the
at
ore
2£
the
rock-breaker
lbs. per
different
floor,in this
By
ton.
machines,
and
any
tions proporit
means
lumps
was were
up.
actual
procedure, K.
with
is
1 lb. to
from
W.
of
filtration.
Lime
The
to
the
crushed
retard
be
differed
cyanide treatment followed
and
lines
first
a
little from
suggested
to
the
the author
ordinary by Mr.
Feldtmann. *
Trans.
Inst.
Min.
and
Met.
London,
vol. vii. p. 124, 1899.
126
CYANIDE
THE
As
soon
as
solution,
0'25
0*15
being this
the
tank
per
cent.
cent.,
per
would
treatment
allowed
not
were was
obtain
to
access
about
27
The
having short
The the the
to
tons was
lost
about
time.
tank
then
ore
67
followed
but
filled,a
was
by
this
of
sand.
transferred
that
its
the
last
given
to
solutions
The when
tank
the
fresh
air
to
would
solution
be
tons).
170
second
the
to
of
cent,
per
It is
Each
to
time
allow
to
was
(165
ore
off
strong the
others,
two
drained
were
object of of damp
mass
row
The it. to on pumped sixty-sixto seventy hours.
stand,
to
filled.
once
KCy,
was
first
the
in
be
PROCESS.
original
value
assay
abundance
tanks,
of
row
this
in
probable entangled in what with would held be in tank of dry sand, as compared a sand settled with water, materially assisted the solution of the gold. Also the finer grains of the free gold would be quickly taken up. A solution of 20 to 25 tons, not exceeding 0*20 per cent. KCy, then sands and drained was pumped on to the transferred off,the allowed remain for about to mass damp being ninety-six hours, solutions when weaker 0*10 to cent, (0*15 per cent.) were per used in continuous washes, making up a total of 75 tons per tank wash of 20 30 tons (second treatment). A water or completed of air
the
this
of the
part
careful
A
the
total
per
tank.
per
cent.,
be and
loss
of
The or,
would
of moisture
the
during
sumps
which
process,
series
liquid in
the
moisture
in the
20
say,
and
tests
of four
treatment
tons
275
some
the
in
form
of
96
was
solutions
dwt.
4 dwt.
to
moisture
from
when
the
0*8
Summary Trial
Tanks Clean
and up
extractor
and
the
tons,
of
fresh of
ton
from
dwt.
to
that
24
or
tons
house
and
sumps
3 tons
of
from
of
the
2£
tanks
second
the 21
carried
per mill tons
row
from
3 dwt.
dwt.
Costs.
.
per
,
ton
smelting, etc.,
Discharging residues, Sundries, FT*
Total
Actual
water
liquid equals
(Coarse).
work,
tanks
ore.
row
of Cyanide Crushing
of
delivered
first
; those
per ton final wash
showed
discharged residues averaged 12*3 tank; the remaining 4 tons would
per
dwt.
32
; and
running
solution
of
(680 tons)
treatment
storage bin, the actual consumption (25 gallons)per per tank, or £ ton The
hours.
measurements
tanks
surfaces represented by evaporation from As the ore contained about by leakages.
tank,
13
last
extraction
68*91
2
3*30
0
5-15
0
8-36
0
1-05
3
5-86
per
cwt.
to
APPLICATION
OF
PROCESS
THE
ZEALAND.*
NEW
principalgold-bearing
The
and
lavas, tuffs, breccias,
everywhere prolonged leaching and accompanied by steam stages of decomposition or hard
andesite
blue
gradations rock,
altered
be
can
into
acid
the
and
by
found
are
in
sible insenblue
or
been
propylite has
name
all the
of almost
fairly hard, greyish-yellow
distinctive
in
mines
many
series
a
doubtless
waters,
They
vapours.
pass
tertiary age. subjected
been
having
thermal
of
to
seen
lower
of
of
alteration;
soft, or
a
which
to
evidence action
the
to
of andesitic
great accumulation
a
agglomerates bear
rocks
These
Goldfields
Hauraki
of the
formation
origin, consisting of
is of volcanic
127
COUNTRIES.
DIFFERENT
IN
applied. It
The
occur.
but
altered
is in this
veins
The
distance.
yet,
adjoining
vary
extension
in linear
is the
andesite
vein
same
from
they
ore or
that
values
lode
few
a
can
the
inches
seldom are
also
worked
veins
be
yielding payable ore 40 ft. in to width,
traced
irregular,and
with
able consider-
for any
payable
in
no
results
case,
in
as
two
mines.
sula, peninportion of the Hauraki of whitish-grey chalcedonic consist the or cryptopay-ores banded of structure crystallinequartz, often possessing a wavy, and blue paratively comThey are flintyquartz. alternating layers of grey base free from sulphides. *645 with The is about silver fine, and usually associated gold tremely sub-sulphide (Ag2S) in varying proportions. It is generally exvisible to the finely divided, being seldom eye, and in the it is impossible to raise even colour ore a great bulk of the Waihi by panning. of the cyanide process, these Prior to the introduction ores were and hot with treated chemicals, pan-amalgamation by dry-crushing 65 of effected. which cent, a was by recovery per When was adopted, dry-crushingwas naturally cyanide treatment different mills,the dry pulverized material at the continued being and treated directlyby cyanide. From charged into shallow vats the 65 bound at to rose a recovery per cent, by pan-amalgamation, Ores,
Cyaniding
In* the
—
southern
.
85 were
per cent., and considered
a
few
possessed *
cases
to
Excerpt
so
years, many
principalbeing American
some
satisfactorythat possible.
considered In
in
from
Institute
however,
90 no
per
cent., and
further
it became
apparent with disadvantages compared
the paper of
cost
of
drying
by author read at Mining Engineers.
the
ore,
California
the
the
results
improvement
was
that
dry-crushing wet-crushing, the low
duty
of
the
Meeting, September 1899,
128
CYANIDE
THE
and
stamps, 1897
mine
and
the
large number began to
owners
PROCESS.
of
their
turn
attention
the
to
different 1898, beginning been have adopting wet-crushing, until at the present time two crushing is the exception and not the rule, as it was
by
one
since
leaching. In wet-crushing,
for
required
vats
one,
of
mills
the
dryyears
ago.
Practice.
Wet-crushing "float
or
gold
"
and
with
(a.) Crushing
containing
ores
able
free, easilyamalgam
of of fine
For
A.
—
with
gold, sulphide, the
silver
large proportion proportion practice is : a
small
a
mill
—
water.
(b.)Plate
amalgamation, (c.)Spitzlute separation of of (d.) Cyanide treatment A
typicalexample of an Estates at Opitonui,
Gold
started. "
The "
double
has
pay made
been
worth
it, they
for
the
for the will
ore,
containing large proportion
small
a
but
a
method
but
of
of treatment
almost
of
the
order
ore
so
the
So
fine
far
slimes.
with
proportion amalgamable fine cyanide gold, with little or no the
at
Crown
of
Mines
could
be
is
:
just the
provision If they are decanting. above,
gold, and slimes,
a
the
—
solution. of mixed
free
exceptionally
of treatment
Kauri
no
described
that
colation. per-
additional
if the
by agitation and
identical
the
of
of free
percolation, Plate amalgamation (c.) an
involved.
treated
(a.) Crushing with cyanide (b.) Direct cyanide treatment
With
is that
40-stamp mill has are subjected to
new
labour
be
class
by ordinary
it is doubtful
treatment
probably
clean
For
B.
a
slimes
slimes
heavy
extra
slimes.
and
this
where
cyanide treatment,
will
saving
and
sands
of
ore
and
sands sands
sands
and
slimes
by
gold^
free
from
reversed
slimes,
it
seems
that
with
advantage, both as regards stamp duty efficiencyof amalgamation on the plates. The Crown Mines the first to adopt wet-crushing was Company for these occurred gold and silver-bearing chalcedonic ores, which and
in
1897,
and
much
credit
is due
to
Mr.
F. R. W.
Daw,
the
tendent, superininauguration of the method. and The is hard splintery,clear and pure from all impurities, ore the unlike of from the neighbouring mines, contains most and, ores silver little or is alloyed with the no gold. It is except what in the Company's crushed in 60-stamp mill with cyanide solution the mortars, about 2£ tons of solution being used to 1 ton of ore. A 2 5 -mesh is 2 tons used, and the duty per stamp is about screen in crushing are formed The slimes said to amount to per day. for the
less than
5 per
successful
cent.
i36
which copper-plates,
amalgamated the
87
all
actual
from recovery cent., but the costs
per
For
G.
of
proportion
certain
a
associated
used
is
is said
sources
to
84
from
vary
to
obtainable.
not
are
containing some with pyrites
ores
gold
and
sulphides,the
silver
fine
gold, and
easily amalgamable
treatment
:
—
(a.) Crushing
with
water.
(b.) Plate amalgamation. (c.) Spitzluteseparation
(d.) Vanner (e.)Cyanide (f.)Cyanide
of fine
concentration
of
treatment
of
treatment
of
practice at
the
if necessary.
slimes,
sulphurets. by percolation. slimes by agitation and decanting. concentrates by agitation.
of sands
treatment
(g.)Cyanide The
catch
gold.
free The
PROCESS.
CYANIDE
THE
mill
Woodstock
is
this
of
typicalexample
a
treatment. The a
and
and the
1100
the
for
The
ore
the
per
is about
June
tons
a
•
mill
the
month, value
equal
is
the
of
2
1000
1901,
which
£1362,
The
a
the
of rich
concentrates.
tank,
passed
vanner
led
are
end
spitzlute. slime
are
over
of which
The
the
slimes
while
the
bullion
tons
of
of
ore
to
a
varies
2240 were
value
of
from
8s.
from
over
amalgamated
by a wheel the spitzlute are ducted conheavy carrying some
pulp
sands
is raised
about
collect
which
vanners,
1
per
cent,
tailings,composed principally of sands and heavy the to leaching vats, which are provided with
distributors.
automatic
through
being principallycomposed ounce, is crushed and with water passed
slimes
slimes,
output
colour
of silver.
to to
The
monthly duty being slightlyunder
ton.
from copper-plates, elevator
It is
pyrites.
presence
of
return
a
j£l, 7s. 6'68d. 12s. per
stamp For
day.
little
a
the
Company's 40-stamp
tons,
lbs. per crushed
and
oxides.
manganese
ing contain-
finelycrystalline quartz,
proportion of clayey matter greyish and blackish-brown
a
of iron
to
chalcedonic
a
small
stained
At
is
ore
The
of the
construction
is of
distributors
those to simplest character, being similar formerly used at of a central Waihi. wooden a They consist box, pivoted on which the in and from" wooden fixed of the centre pillar vat, extend and wooden launders of light make seven narrow or arms different of the distribution lengths, so as to effect an even pulp. At of each zinc to there the end is fixed a piece of sheet arm
the
divert The stream
the
stream
whole and
to
of the
diverted
one
pulp into
side. from
the
one
vat
ends
vanner
at
a
time
is collected until
the
in
one
charge
is
AMPLICATION
filled.
During
the
slime
vats.
the
into
OF
THE
PROCESS
IN
DIFFERENT
overflow
fillingthe
131
COUNTRIES.
the
carries
lighter
slimes
with treated are cyanide by heavy slimes ordinary percolation. those from the sand vats, are The slimes the spitzlute,and from slowly revolving provided with agitated with cyanide in vats the lime is added, and slimes the gold is dissolved When arms.
The
and
sands
allowed
are
The
off.
slimes
and
of water The
which
settle,after
to
washed
are
with
by agitating
is decanted
solution
clear
the
successive
portions
decanting. have
concentrates
value
a
of £30
,£40
to
ton,
per
large
a
silver
sulphide. They are being proportion of cyanide for treated by agitation with a 4 per cent, solution to Two of thirty-sixhours. pounds of lime are added every ton Mr. F. Eich, The concentrates. 1J tons. charge weighs about the the superintendent,who adopted present treatment, informed of
the
of 18s. per
cost
The
able
very
gold, usual
varied
recovery for
from
vary
For
D.
the
to
ton
in
and
silver
82
and
labour
86
to
per
sulphides,the
of sands
(c.) Treatment (d.) Treatment method
94
to
cent.,
per
at
a
material. sources
cent.,
at
a
of
per
ton
cost
of 4s. 9d.
ore
milled
containing very little easily amalgamslimy ores a large proportion of extremely fine gold besides is
treatment
(a.) Crushing with cyanide (b.)Spitzlute separation of
This
90
from
all
from
by cyanide
recovery
is said
the
that
author
value
the
as
:
—
solution.
sands
and
slimes.
by percolation. by agitation and
of slimes
follows
decanting.
modifications subject to various as of application, but regards mechanical appliances and methods the general principles are the everywhere same. the The Waitekauri at 40-starap mill is as follows : procedure contains which The a good deal of oxidized products, is ore, is
of treatment
—
crushed the
with
cyanide
is conducted
pulp
in the
solution direct
to
sand
the
distributed from
a
of revolving wooden by means The slimes, of secondary shaft.
cent.,
per
through movable in the
are
allowed fixed
a pipe joint,and
to
in
drain
the
is raised
into
inside
by
a
screw
of
box
a
as
launders there
screens
which
vats, into
which
the
the
From
mortars.
are
it is
actuated about
33
collecting vat, flowing This vat. pipe has a the pulp accumulates
vat.
which collectingvat is provided with revolving arms keep this the fine slimy pulp from From the slimes vat are settling. with into which the slime are a leaching vats, provided pumped rakes double the lower set of slowly revolving arms, ones having The
132
CYANIDE
THE
and
them
on
the
the
pulp. decanting,
through and
loose
ones
upper In
these
lime
PROCESS.
the
vats
being
which
pieces of sacking slimes
added
treated
are
each
with
wash
drag
by agitation facilitate
to
settlement. The
sands
solution
cent,
per
treated
are
of
by ordinary percolation with the then weak cyanide, and
first
a
and
water
0*5
washes. There
each
vats
2 2 '5
value per The
ft. in
slime
diameter
and
output
is about
cent., at
per cost
a
ounce.
of 5s.
vats, and 4
of
tons
than
valued
2
deep.
ft.
2200
larger
was
of bullion
ozs.
1 8s. 9d.
of
14
vats,
40-stamps
monthly
yielding 7220 90
sand
of the
output June
12
are
slime
collecting monthly
The 2240
lbs.
The
usual, being 2543 tons, 0s. 6d., £6773, equal to a
at
The
actual
6d. per
ton.
recovery
is said
to
be
exceptionallylarge proportion of slimes in this ore rendered the adoption of wet-crushing a knotty and difficult problem. The increased lower costs are output, higher extraction, and proofs of the change from dry-crushing which enough of the success was under the G. effected supervision of Mr. Davey, the superintendent, without in the hitch, or decrease monthly output, a in these of of no little moment matter days heavily capitalized public companies. the points most Among Concluding Remarks. likely to attract low the the notice of cyaniders are stamp duty and the heavy consumption of cyanide. mills has often Zealand The low stamp been duty of the New a but been of has discussion, no subject satisfactoryexplanation yet In the opinion of the author, it is due the to stance circumadvanced. that the mills having been designed and erected in the first and restricted too are narrow place for dry-crushing, the mortars until results these and to give good are replaced by wet-crushing, for it wet-crushing, seems mortars, speciallydesigned by new less hopeThe for better of results. to look advantages a stamp duty of of 2 tons obvious 4 or 5 tons too to are require per day instead —
enumeration. With known effect
reference that
to
silver
its dissolution
the
in all than
large consumption its forms requires a
gold ;
and
large consumption of cyanide is sulphide (principally Ag2S), which to
the
third
circumstance its
that of silver.
the
free
to
stronger
the
is
well to
Goldfields
presence worth
generally gold is alloyed
weight According to Eisner's equation for potassium cyanide, 4 lbs. of cyanide that gold, but in practice it is found
it is
solution
cyanide,
Hauraki
in the
due
of
with
of
the silver
saving, about
aud one-
^ the
dissolution
should it takes
dissolve
of 100
gold by ozs.
of
nearly forty times
OF
APPLICATION
PROCESS
THE
that
quantity. To dissolve lbs. of cyanide, according to 4Ag For
the
+
8KCy
+
dissolution
sulphide (Ag2S), 7*01 following equation :
IN
100 the
+
of
100
—
silver
of
ozs.
would
cyanide
lbs. of
:
4(AgKCy2)
=
require 7*5
would
silver
equation
2H20
02
of
ozs.
133
COUNTRIES.
DIFFERENT
4KHO.
+
existing as the subbe required by the
—
Ag2S
+
4KCy
2(AgKCy2)
=
+
K2S.
of silver potassium sulphide resulting from the dissolution shown loss of cyanide. It has been a sulphide also tends to cause of alkaline by Crosse and others that a trace sulphide in cyanide but the solutions does not act injuriously, large quantity of K2S of the silver-bearingores of the Hauraki liberated in the treatment the precipitationof a portion of the dissolved Goldfields must cause of this Much precipitated gold is doubtless gold in the vats. redissolved of free cyanide present in the solutions, by the excess obtain but it always requires this excess to adequate extractions, the thus of comparatively strong solutions. use necessitating with the One connected ment treatof the most perplexing features is the constantly varying proportion of silver, of these ores solutions which the of varying strength to. necessitates of use of anxiety obtain source adequate extractions, thus adding another the the which the use of cyanide entails on worries to even many successful cyanider. of the Hauraki At many was mines, cyanide treatment adopted but the author's recommendation, by the owners only after he on careful of the had made a investigation of the constituents ore, lurgical MetalGovernment and repeated trials on a working scale, at the The
Works
experimental In
mine.
no
the
at
trials case
made
were was
In
Thames.
the
the
by
process
The
a
ores
of
Te
Aroha
and
Monowai
cases,
author's until
adopted
doubtless precaution which promoting the popularity of cyanide
assured,
other
has
been
treatment are
the
necessary
assistants had
success a
in
potent this
generally
the
at
been
factor
in
country. very
tory, refrac-
fine, associated containing free milling gold, mostly very with lead, zinc, and often cury. mersulphides of silver, iron, copper, them to treat Many attempts have been made by cyanide, it but without and, so far as our present knowledge success, goes, doubtful treated the if in is be raw they can ever successfully that state by process. from For the of cupriferous ores and treatment concentrates be could Monowai the not Jubilee, Sylvia, and mines, which obtained treated successfully by ordinary cyaniding, the author good results by first subjectingthe ore to a chloridizing roast, and
134
then
leaching
alkaline
and
the
out
PROCESS.
CYANIDE
THE
chlorides
copper
with
After
water.
an
were tracted exgold and silver contents by cyanide by ordinary percolation. Daring the roasting the silver chloridized, the chloride sulphides present were being dissolved easily by cyanide. From Monowai of the cent, a large parcel of gold ore, 92 per and 85 per cent, of the silver extracted, the composition of were the ore being (F. B. Allen, M.A., B.Sc.) :—
wash,
water
Insoluble
the
90-15
gangue,
Copper pyrites, Iron pyrites,
3-78
Galena,
0-25
4*40
.
Zinc-blende,
0-26
Alumina,
013 .
and
Water
103
loss,
10000
bullion
The
silver, 14 The
of
Co.'s
construction,
equipment,
consists
of
and
in
a
were
:
Gold,
—
situated at Works, of point completeness
the
finest
1
dwt.
5
oz.
;
in
Thames, and
Zealand.
New
are
modernThe
plant matic rock-breakers, grizzlies,autobattery, Berdan 21 a complete cyanide vanners, pans, among
60-head 24
feeders,
ore
ton.
Moanataiari
of recent ness
per
oz.,
this
of
contents
two
9 Cornish buddies for concentrates, plant for treating vanner all up-to-date and the vanners, concentrating the tailings from The and for consist retorting. cyanide works appliances assaying steel vats, 20 ft. in diameter and 7 ft. deep, each of three provided with each with of 200 two doors, a bottom-discharge capacity of
tons
concentrates
length ; and Wet-crushing,
three
works,
supervision. in
New
concrete
were
The
interesting
designed by cyaniding of
each
extractors, sumps,
concentration, the
are
which
zinc
; two
and
the
features the
50
x
1 1
15 x
6
ft.
6
ft.
over
cyanidation of the practice
of
author
and is
concentrates
erected
in.
the at
under
comparatively
in all.
centrates con-
these his new
Zealand.
Mine.
Talisman
In
the
Ohinemuri
Goldfields,the practice has been of dry-crushing cyanide treatment superseded and of sands, treatment cyanide by wet-crushing, concentration, and
slimes, and mill, the ore
being dumped Blake
Marsden
in was
some
—
direct
cases
the
concentrates.
At
the
Talisman
the mine conveyed from by an aerial tramway stuff to a grizzly,which to on a passed the coarse the ore crusher, whence passed to a revolving ,
APPLICATION
The
drying furnace.
provided
were
PROCESS
THE
OF
and
pulverized ore was the carried to cyanide conveyors.
drying
12
about
This
by
vats
tons
of
to a
was
for
ore
every dry-crushing mill
place sands
and
ore-bin, from line a
ton
has
the
mortars
which
it
of
very
was
revolving screw^ machine,
efficient
of firewood
consumed.
dismantled, to give wet-crushing plant. Wire gamation, plate-amalconcentration, separation of slimes, cyaniding of vanner slimes, the latter by agitation and decantation, has been
company's a new 50-stamp
to
an
long
drier
mechanical
The
135
COUNTRIES.
front
elevated
The
DIFFERENT
weighed 1000 lbs., and discharge.
stamps
back
with
IN
been
introduced.
Waihi
lode
Martha this
Mine. at
the It
district.
The
—
Waihi
in the
ore
mine
is
upper
levels
typical of
celebrated
the
of
of
most
the
in
ores
principally of hard, splintery, whitishchalcedonic and crypto-crystalline quartz, often possessing grey It is all base free from and wavy structure. perfectly a banded of iron metallic oxides sulphides, and the amount present is so small
that
when
consists
roasted
and
pulverizedthe
colour
of
the
dust
is
pinkish-grey. value
"£4
£"
precious metals to oz. oz. gold. The proportion 35 about free of cent, silver, being gold is alloyed with per The about 53s. valued at oz. greater proportion of the per silver exists in the form of the bluish-grey sub-sulphide known as In thin the surface levels, argentite. leafy plates of gold were the not surface of large cuboidal to infrequently seen adhering lower levels of quartz, but in the is rarely seen, colour masses a the gold existing in an Such extremely fine state of subdivision. is theoreticallyperfect for cyanide treatment, and actual an ore has it be old to the proved so. By experience stamp battery, and amounted to only some copper-plate amalgamation, the recovery 4 dwts. per 15 cent, of the value. ton, equal to about By per raised to was dry-crushing and pan-amalgamation the extraction actual 60 per cent., but the extraction at present by the cyanide The
varies
from
existing in the
process The
amounts
to
of about
to
over
90
per
per
3
cent,
ton, the
silver
of the
1
assay
value.
of treatment following particulars of the dry method the Waihi mills were at formerly in use supplied by Mr. H. P. for the annual Barry, the general manager, report of the New Mines for 1894 Zealand : Department The is Ore. trucked the to the ore drying kilns which Drying —
—
consist
of
open
circular
holes
excavated
in
the
solid
rock,
their
the at being 37 ft. in depth and 20 ft. in diameter the kiln is capable Each at bottom. top, and tapering somewhat of ore at lower of holding 100 The tons a charge. part is lined with bricks, and finished off with a brick arch, having a door
dimensions
136
CYANIDE
THE
and
iron
an
which
chute
have
dried
discharging the the kiln by means
for to
access
PROCESS.
of
a
into
ore
tunnel
trucks, in
cut
the
rock.
Charging the Kilns. and layers of wood ore, When is all
and
necessary
wood,
of
withdrawn
ore
are ore
The
are
alternate charged with being about 5 ft. apart. is lighted, and, after it
layers of wood the kiln is fully charged, the wood half the charge, that burned up, about
withdrawn
raw
kilns
The
—
and method
the
another are
wood of
50
the
placed on
third
every is added.
drying
of
tons
the
ore
ore,
raw
top.
day,
is about
After while
a
50
together this
about
similar
is very expensive, as of ore. The cost tons
tons, is the
with 50
tons
quantity one
ton
of
of
of firewood only dry about three of the and mill ton is 2s. total cost at dried, ore big per of drying, including labour, is 2s. 6cL per ton. From the is kilns, the dried ore Pulverizing. Crushing and it passes trucked to the rock-breakers, whence by gravitation to of a The self ore-feeders. the pulverizing machinery consists Otis an ball-mill,having a capacity of 90-stamp battery and about The is passed through a 40-mesh 10 stamps. screen. ore the Vats. From the the Leaching dry Filling Cyanide screens, dust falls into trough running parallel with the a long, narrow the dust-bin it is conveyed to at one stamp-motors, along which From end of an Archimedean the of the mill screw. by means elevator and the pulverizedore is lifted by a bucket-belt dust-bin provided with rope edges, discharged on to an 8 in. rubber-belt and the is dust-hopper, which by this conveyed to, and across, 110 ft. long, running the entire length of the cyanide-plant house. The dust-hopper has twenty doors for discharging the dust into the the trucks, which are straight out over leaching vats on run travellers The to travellers are provided with running on rails. hand be to tipped at traversing gearing, thus enabling a truck This is an important feature, as the finely part of the vat. any about has a tendency to pack if moved or pulverized material the touched into after vat. in any being tipped way is a small As a further preventative against packing, there traveller fixed below the main traveller, provided with a platform All the trucks has to be filled up to. at the height the ore are the breaks fall of the this platform, which dust, and tipped over all in it around. throws a light shower The The Treatment. Cyanide following particulars of the cyanide treatment were kindly supplied to me by Mr. E. G. Banks, of the cyanide operations. the chemist The plant consisted of thirty-eight circular leaching vats, each 22 J ft. in diameter and the necessary 4 ft. deep, together with
wood
will
the Waihi
—
—
—
OF
APPLICATION
dissolving and and
solution
PROCESS
THE
solution
vats,
air-pumps,
etc.
IN
extractors, vacuum-cylinders,
sumps,
:
137
COUNTRIES,
DIFFERENT
—
Hours.
Filling vat, 30 tons, two men, Strong solution, 10 tons, 0*35% KCy leaching, Weak solution, 7 tons, 0*1% KCy, with vacuum, First
6 tons, with
wash,
water
2£ 30 .
15 24
vacuum,
.
.
36
Second „
„
.
„
2
Discharging vat, one man sluicing, Taking up and cleaning filter-bottom,
...
4£
.
.
.
.114
Total,
.
.
•
A
of 20
vacuum
The
results. the
actual
extraction
and
been
at
a
abandoned
of the
value
average
original value, at Dry-crushing
in. is maintained
23
in. to
to 92 cent, per per cent, 7s. 6d. per ton, not including
of
direct all
the
slimes.
and
The
South
of the
treatment
African
subsequent
and
Western
Mr.
G.
slimes
is
of
the
some
of
treatment
effected essential
the
royalty.
pulverized ore cyaniding Waihi Company's mills in favour
combining tilter-pressing,
both
of
the
of
wet-crushing, concentration, and and
above
ton, and
90
from cost
the
obtain
«£4 per
about
was
ore
to
has of
sands
by agitation features
of
Australian
practice. Banks, company's metallurgist, for am Waihi notes the following clear and succinct on cyanide practice The is pulverized by mills. different Victoria mill. at the ore and wire steel screens, 200 wove stamps to pass through 40-mesh launders of plunger sand is then to elevated by means pumps the where of which nests the spitzluten pulp to tion separaconvey slimes and takes place. of the sands I
indebted
to
the
—
Treatment
of
Sands.
—
sands
The
flow
to
the
intermediate
sand
meter five built of steel, 38 ft. in diathere are collectingvats, of which the outside launder on by 8 ft. deep, fitted with an annular the overflow times containing a little water, at top edge to convey The sands are charged to the slime slime, away thickening boxes. tributor, automatic into the percolating vats of an revolving disby means which as
is moved
on
an
overhead
traveller
from
vat
to
vat
required.
The bottom-discharge doors. filter-bed is arranged by a wooden grating covered with wool-pack. After 250 of sands. holds from vat Each to 300 tons draining to is given with get rid of surplus water, a preliminary treatment weak cyanide solution, followed by a strong (0*35 per cent, to and usual washes, Q*45 per cent.) solution The
vats
are
fitted
with
Roche's
138
THE
The on
side.
Slime
Each
4 lbs. of lime
mixed
are
which
off in
The
slimes
thickened
The
14
by clear
ft.
In
deep.
from
the
nest
bottom the
to
collected
slimes
it is stored
2
to
V-shaped then
are
the
of
boxes.
stamps.
in six steel vats
the
these
overflows,
water
(about of 36
a conveyed quickly settle, and
is returned
are
lime-water to
state
a
with
sliinea
the
fairly thick overflowing clear water
drawn
rectangular concrete vats, five 40 ft. and ft. 4 by deep. from the spitzluten and the overflow
slime) and
of
in
ft.
slimes
vats
ton
per boxes
thickening
The
—
sand
the
ten
is 50
vat
Treatment.
from
the
contains
old vat-house
each
PROCESS.
CYANIDE
meter ft. in dia-
32
rapidly settle, and
for
the
in
re-use
as
and
mill
spitzluten. the
When the
top,
settle is 1
for
is filled with
vat
inflowing slimes
the
about
hours.
24
syphoned off,and of water) is ready The
the for
slime-pulp
off and
Whatever
clear
treatment
of
the
2
3
or
may 1
ft. from
allowed
charge
water
pulp (now about in the agitators.
thickened
built
within
to
cut
are
be of
to
top
on
slime
to
ft. in diameter
by 6 ft. deep, and 25 tons of slime hold about (dry weight),together with about 40 tons of cyanide solution. The strength of the solution is about The is O'l per cent. pulp agitated by paddles, secured to a vertical The shaft, actuated by overhead worm-gearing. speed is 8 agitators are
revolutions After and
24
per minute. hours' agitation the the
where filter-presses,
The
work,
method
zinc
on
even
Vanners
of
dilute
very
to
can
of 85
extraction be
recovered
recovery In the
crushed bullion
Waihi of
The
ore.
or
by
costs
are
month
of
12,968 valued
Union
40-stamps
for
steel vats
cent,
to
90
but
process,
per no
through
pass
of
cent,
heavily
more
will
vanners
be
the
mixed course
the
ore
value
of
the
actual
particulars
yet available.
January of
tons at
per
this
the
concentrate
the tailings from and with the lightly mineralized ore-pulp, of treatment just described. An
to
run
solutions.
erected
being
are
mineralized
tank, a pressure 6-ton by compressed air into Johnson gold bearing cyanide solution is extracted. precipitation is used and does very good is
pulp
is forced
thence
from
steel,20
of
which
ore,
this
year,
the
Waihi
yielded by cyanide
Company treatment
£29,055. and
This mill consists Cyanide Plant. and wet-crushing plate-amalgamation ; sixteen
Mill
sand
—
(each vat having a capacity of sand) ; three of 22 tons slime-collectingvats, 32 ft. in diameter 14 two ft. by 6 ft. deep; deep; agitators, 20 ft. in diameter by of 6 of slimewith tons Johnson and one a capacity filter-press, dry weight, per charge. In addition there are the usual ore^
circular
for
treatment
i1
/ I.
z\
I
.
ELEVATWH
SECTIONAL
\TATOR J
ARMS
10
—
7
—
Scale
II
.2
T"
by
of Feet
111"1"""1
f»
APPLICATION
OF
breakers, used
spitzluten, 40-mesh
are
25
ft. and Sand
by
Treatment of
means
automatic
an
run
The
on, and total time
0*07
of treatment
through away The Treatment.
Slime
(about
3 lbs. of lime
vats
and
part
of slime
with
there
are
to
one
The
automatically. to
boxes. that
This even
£ grain
from water
6d.
the
used
are
8d.
or
allowed
were
From
drawn
equal with
to
mills.
to
run
to
25
Mill.
—
the
off
provided
syphon
a
one
clear
top the
water
settling vats
in
the
mortar-
ton
of ore,
of
tons
loss would
the
shillingsper
several
as
be
from
if the
water
waste.
at
slime, and
dry
thickened
the
settling vats,
for
ore
about
to
a
are
lower
some
years
Washoe
was
; and
slimes in
level,
agitated
cyanide solution to 1 ton per cent, This Waihi of the oldest is the
the
lime-water
large collecting
the
ton, and
per
it is evident
of ore, three
of
tons
of 0'1
Here
gold
agitators, situated
the
1 J tons
Waihi
or
to
appears of
collecting or
to
20
two
to
the off
ton
per to
up
water
2£ grains
to
strong.
owing to the fact necessary be perfectly clear it contains
be
to
0*6
of
the
to
overflowing from for re-use pumped up
is found
course
when
cyanide,
to
addition
water
be
to
sump-
of
The
vats,
drains
weak
cent,
settlement
these
In
joint
clear
reservoir
a
natural
by
water.
ball-and-socket
a
is sent
of
A
days. tailings discharge-door.
the
after
distributed
six
ore), flow
of
per ton thickened
are
per solution 0*4
a
central
slimes,
by and
O'l
to
five to
bottom
a
—
vats
screens
passing the a height of spitzluten.
to
four
distributor.
cent,
by
slimes
the
to
is from
sluiced
are
and
flow
per is followed
this
a
revolving
about
wash, containing is
sands
after
pulp
wheel-elevator
sands
into
The
—
by
the
The
etc.
compressors,
steel, and
139
COUNTRIES.
DIFFERENT
air
is elevated
classified
is here
IN
pumps,
wire-wove
tables
amalgamated
PROCESS
THE
for
are
charges
24
hours
dry slime. Company's dry-crushed and panafterwards dry-crushed, of
amalgamated by process and the dry pulp cyanided by the direct in the manner process Of the described Mr. in the Barry preceding pages. by present Mr. Banks in April of 1903 treatment follows writes : as old At the stopped at the 90-stamp mill dry-crushing was end and of 1902 for wet- crushing rapidly alterations necessary the of middle 1 restarted. 903, the mill was completed. By January The ore (about 220 tons per day) is stamped through 40-mesh wire- wove steel screens amalgamated tables, of which ; passed over there fifteen,each 12 ft. by 6 ft. ; and then over are thirty union —
"
vanners
After to
a
which
passing
series of sand
f"
the
vanners,
to
pulp boxes.
separating being taken
separated, care slime as possible. Treatment of the are
2£
about
extract
the
Sand.
—
This
to
of concentrates. 4 per cent, is elevated elevators by wheel Here
keep
the the
and
sands
sand
as
is effected in circular
free
vats
slimes from
4J
ft
140
deep
and
40
tons
of sand
the
sand
is then
dealing with
of
capable
PROCESS.
CYANIDE
THE
is first filled with
and
charge.
per
The
in
through overflow The water revolving distributor. (carrying annular into and slime) runs launder and is an a little fine sand wheels and joins the pulp flowing conveyed back to the elevating When sufficient sand has been boxes. the into to run separating the vat a 2 in. draw -off pipe, passing through the side of the vat, vat
water
run
automatic
an
is lowered
and and
little slime "
wash
After
the
by
charge
washed
then
sluiced
"
Treatment
water
0*08
per solution the
five
KCy)
cent.
testing by
solution
weak
hours, is
0*5
of the
bottom
days the strong
with
also
water
for several
circulated
solution
contains
a
on,
weak
sump
and
this
is
KCy charge, percolation
means
water.
; when
cent.
per
solution
and
run
a
of
an
is drawn
The
air-lift off
is
inside
and
the
tailings are
away.
of
pulp (about and
drained
has
This
off.
elevating wheels.
the
reached
the
After
vat.
slime
to
strong has
stopped and the
flows
charge
a
solution
drawn
water
(testing about
followed this
the
the Slime. 20
—
of water
conducted
over
After to
a
nest
1
separation from the sand, the of slime) is mixed with limeof spitzkasten, thickening the of the water slime, the balance
slime-pulp per cent, of in the mortars. in a clear state to be re-used passing over of two The collected in one slime-pulp is now collecting vats, ft. in diameter, and which fitted with 14 ft. deep by 32 are an the The of the centre overflow and launder. to vat pulp is run chute several vertical box below feet extending discharged through a little the top of the vat, so as to cause disturbance as as possible. the show clear until the the The in slimes at water runs pulp top, The collectingvats thicken overflowing to a reservoir for re-use. the pulp to about to 1 of slime. 2 J of water still further thickened is The slime pulp now separated from of of which the contained water two filter-presses, by means 40 are required for drying the slimes, each dealing with about tons (dry weight) of slime per day. " The slime-cakes, now containing only 25 per cent, to 35 per the from to cent, of moisture, drop on a presses screen-conveyor This into which a disintegrator. disintegrator is 7 ft. discharges in diameter by 14 ft. deep and fitted with three sets of revolving driven shaft bolted to a centre by overhead arms gearing at the revolutions of 20 minute. rate (0*12 per Cyanide solution per the such flows in the of in bottom at disintegrator proportion cent.) that the overflowing pulp contains 1 of slime of solution. to 1£ 14 ft. deep This pulp flows through a series of four agitators each by 20 ft. in diameter, fitted with stirring gear making three to about
10
"
"
*
revolutions
per
minute.
'
142
wis
of thd
cost
"The
work
probably
to
out
CTAHIM
MtOCftSS.
siime
treatment
is
about
6s. 6d. per
ton
Waihi
of the
Company
given, but
not
of slimes
it will
treated.
is about
18,000 long tons of four weeks twenty-four working days, for a return every The to is pulverized in £50,000 £52,000. ore varying from 320 the company's mills, comprising stamps, and then subjected the various above. described to by cyanide treatment processes 1000 The tons a capacity of about cyanide plants have per day." the From the foregoing description it will be that slime seen Waihi Waihi and Union mills in use is practically at the process Western in the same that in at On Australia. use Kalgoorlie as the other mills hand, the process at the Waihi Company's Waikino "
The
output
with
identical
almost
is
that
in
Johannesburg, differingonly in the of filter-presses to separate solutions decantation
is almost
which
Waihi
Tailings.
—
final
stages the
from
universal
The
Glencairn
at
use
of
a
60-mesh
and
screen,
discharged
were
The cyanide process. pan-amalgamated
of the
allowed
from
the
settlers
into
the
adoption instead
Waihi
ore
was
of
Company's
residues
crushed
charges. large dams,
ing result-
before
ore
in
consisted
settle.
the
Reef,
Africa.
The the tailingsare tailingsis very instructive. the pan-amalgamation of the dry -crushed from
introduction
in
slimes
in South
treatment
Main
the
through
The
residues
where
they
They mostly a contained base metallic no They good impurities, and the gold existed principallyin the form of amalgam. Some 25,000 tons of these tailingswere successfully treated by Gold whose works the Cassel have Extracting Company, recently Waihi Gold and the Silver been acquired by Mining Company, of the the remainder who their treated account. tailings on own The plant consists of eight leaching vats, each 22£ ft. in diameter all the 4 ft. deep, together with and appliances. necessary The details of the cyanide treatment adopted for the treatment in tabulated below of these form : tailingsare given were
deal
to
of fine
sands
and
of slimes.
—
Treatment
Cyanide
Waihi
op
Tailings. Hours.
Fillingleaching vat, Preliminary lime or Leaching
.
Strong Weak
30
tons, three
water-
wash,
6
men,
tons,
8 ...
with
6
vacuum,
—
solution, solution,
8 tons,
4 tons,
0*6% KCy, 0*2% KCy
.30 .
.
.
(from strong sump),
12
APPLICATION
Washing, First
OF
Vacuum
using
weak
PROCESS
THB
IK
DIFFERENT
143
COUNTRIES.
—
(from weak
wash
cyanide
sump),
4 tons,
Second ,,
,,
„
Third
Fourth,
wash,
water
Discharging
vat,
4 tons,
sluicing,
man
one
Total, Remarks.
The
—
lime solution four
hours
value
stand
to
the
before
Fluke
75
Mine.
commenced.
percolation was
tailings
about
extraction
generally very clean, and the preliminary not was always applied. The strong in contact with the tailings about
wash
water
allowed
the
of
.
.
tailingswere
or
was
.108 .
per At
about
was
24s. the
cent., at works
the
The
ton, per of 8s. per
cost
of this
Company,
and
average
the
actual
ton.
Kuaotunu, and through a 40-mesh passed screen, over amalgamated copper-plates. The tailings were run directly from the plates into the full, the settling-pits. When pits were from slimes were removed the lower end, and out to dry in spread the sun. broken and When then filled were dry, they were up, into] the leaching vats together with sand, in the proportion of Try
the
ore
one
truck
of slimes and
solution
author
at
wet-crushed
was
sand
The the
—
that
slimes
put
was
the
trucks
two
to
The
mixed
in
the
before
vat
Company's metallurgist informs of treatment
time
average
sand.
thoroughly
were
on.
of
was
follows
as
:
the
—
Hours.
Filling vats, 20
tons,
Strong solution, in contact
with
Percolating, Weak
5
solution,
tons, 0*6%
tailings, .
containing
a
.
.
.
.
.
.
.
.
five
Totals, consisted
8 to
12
standing
0*2% KCy,
cyanide washes, 0-1% of KCy,
ore
8
24 .
5 tons,
Weak
The
KCy,
6 to
of grey
considerable
of
.
to
5 to .
5
6
.
each,
tons
.
30
.
25
to
30
68
to
86
.
and
yellowish-brown quartz, sometimes proportion of iron and manganese
generally predominating. The greater part of float gold." known the gold was excessively fine,being locally as about 20s. value of the tailingswas ton ; and The per average 75 per cent., at a cost of extraction the actual by cyanide about When the of higher value than 7s. 6d. per ton. tailings were in the vat after the last washing and turned over usual, they were
oxides,
the
latter
"
144
PROCESS.
CYANIDE
THE
found that it was the extra extraction again. In this case labour. than paid for the extra more At the Kapai- Vermont mine, which adjoins the Try Fluke, the same ore was dry-crushed in a ball-mill, and then subjected to direct cyanide treatment with the most satisfactory results, the actual 85 extraction of the generally exceeding per cent, assay value. In this mine, shoots have been of very rich ore frequently met with, containing a considerable proportion of comparatively the such coarse gold. With ores was strong cyanide solution circulated through the leaching vats until an adequate extraction washed
obtained.
was
Waitekauri
Mine. Gold
Waitekauri
Golden
the
At
—
Cross
section
of
the
Waihi, Company's Special Claim, near the ore, before the introduction of wet-crushing at the new mill, dry-crushed with stamps to pass through a 40-mesh was screen, and treated directly with cyanide. As a small proportion of the the gold was tailings were amalgamated passed over coarse, and with fall 30 ft. ft. 3 of 1 in 12. set wide, a copper-plates, long of this ore The details of the cyanide treatment may prove statement useful, and are given in the following tabulated :
Mining
—
Hours.
Filling vats, three
22
men,
tons,
3^
....
45% KCy, Strong solution, Weak 9 solution, tons, 0'2% First weak cyanide wash, 5*5 tons, 0*05 9 tons, 0
Fourth,
„
.18 „
„
3*0
wash,
.18 „
sluicing,
man
one
Total, value
average ton; and at
the a
of the
actual
cost
Kalgoorlie, in
occurs
unoxidized In
all
cases
chief
oxidized
the ores
in
it exists
during
1894
from
91
per
15s.
£4,
was
cent,
to
93
ton.
mining
surface
ores
combination in
J
.
Sulpho-Telluride
of
the
.
AUSTRALIA.
WESTERN
Treatment
.
.
varied
extraction
of 8s. 6d. per
.
.156 treated
ore
.
14
.
.
The
18
.18
„
water
Discharging vat,
At
0*15%,
5'5 „
cent.,
.
to
„
„
Third
per
.18 .
5*5 „
per
...
"
„
Second
48
an
in
centre
in with
extremely
Ores.
a
the
free
state,
tellurides fine
State, and
condition
the
and
in
gold the
sulphides. in
talcose
APPLICATION
OF
calcareous
that
ores
successful
The
difficult
possesses
The
climate
and
the
But
these
the
to
tropicaland
was
distance
difficulties
have
supply, provides an abundance distance exceeding 300 telluride
ores
of the
slimes.
and
proportion The mines
Diehl
and
with,
it is
will
of them In
of the
some
be
the
difficulties
ore
slimy
many
often
kind
the
plains.
State
in
in
railway
consequently into
the
of
a
the
ore
mills
larger sands.
led to
the
of
the
treatment filter-press
the
State
a
the
world, pipe-line for a
a
than
ore.
brackish,
arid
over
capital,and
the
slime
as
high
installed
at
several
is to
a
possible.
as
have
processes
been
in
Chapter
mills the
slimes
detailed
A
said, satisfactoryresults.
found
rebellious
and
A
character
and of
the
overcome.
water, carried
process
Riecken
of the
early
brittle,and very into the slimes goes
cyanide object at
The
respects
the
are
of the
adoption
some
great, and
been
now
of pure miles.
gold
circumstance
in
scarce
with mining centres greatest .undertaking of
the
water
that
of
distant
the
proportion
dry, seaboard
the
from
water
presented a repeated failures
after
treatment
mere
slimes.
form
to
first
at
ores
and
metallurgists, was developed process And peculiar features.
confined
not
This
these
of
145
COUNTRIES.
great propensity
a
possess
DIFFERENT
lines, a
were
The
IN
to
some
connects
PROCESS
treatment
problem
old
along
THE
description
XIII.
drained
are
partiallydried in cyanide solution, and or
disintegrated and agitated with In in presses. other mills, the pressed and washed of the dissolution gold is effected directlyin the presses. F. B. Allen, M.A., B.Sc, Director of the I am indebted to Mr. Kalgoorlie School of Mines, for the following interestingdetails of the of treatment adopted at that mining general methods
presses, afterwards
centre
:
—
General.
—
essential
The
of
features
the
treatment
dry-
are
fine
circumstances, according sliming, crushing, roasting or with and filter-pressing. cyanide, leaching Brown The or roasting is generally effected in Edwards The former from 14 16 roast to tons straight-linefurnaces. per and 6d. 30 of 4s. 4s. to ton at cost tons Brown, a day, ; per per for 7s. 0*1 to 9s. ton. to cent, as sulphur sulphide day per per is dried before of moisture 3 per cent, Ore drycontaining over ball-mills. No 5 Krupp, running at 25 revolutions crushing in crushes with 15 25 minute tons H.P., through a 40-mesh per not
to
.
for
screen
pass
a
mesh, a
Is. 2d.
100-mesh will form
100-mesh
Great
of this from 65 per ton, and The sieve. Griffin mill, when
a
of
which
product an approximate
sieve, at Boulder
Proprietary.—
75
per
cost
The
cent,
to
75
crushing will
of 2s. per
will
cent,
per
to
a
15-
through
pass ton.
sulphide
ore
is
10
partly
146
CYANIDE
THE
crushed
with
wet
Griffin
partly dry-crushed in
in Wheeler
amalgamated
and
stamps
PROCESS.
fed
mills, roasted,
and
pans,
which
mixers
into
the with is further ground and pulp, which supply Wheeler pans without with of copper-plates. the use amalgamated mercury the continuous of the The pulp from overflow Cyanide Process. of sulphide ore, is led into settlers, first passing, in the case pans —
tables
canvas
over
the
gold
they
roast
and
2*0
the
per
of
recovered
are
Edwards
are
one-third
About
concentrates.
* The furnaces by amalgamation. (16 tons per day), fed with producer gas, and down 0*11 to cent, sulphur as sulphide, per used are sulphur as sulphate. Push conveyors taken is samples are automatically as the ore
contents
used
eliminate
to
ore
cent,
throughout, and discharged from the elevators. The
slimes
fine
settler
the
from
to
go
a
and lifted up passed through they are the The to slimes, 1 particles being returned pans. and to montejus or pressure-tanks, and agitated passed filter-presses. The
Dehne
four
hold
presses
3
3J tons, forming hydraulic pressure.
presses
solutions
The
three
boxes, and
in.
by
tons
cakes.
each;
the
They
are
Excelsior
presses, with treated
the
gold-slimes tiltingfurnaces. residues dumped by a Ledger wood are
zinc
melted
and
clarified
are
4
The
whence
settling tank, spitzluten, the
heavier
1,
to
are
then
to
Martin
five
worked
by
passed through sulphuric acid
in
hoist
to
on
60
a
ft.
heap. Mine.
KalgOOrlie
Part
—
of the
is dried
ore
in
White-Howell
a
passing direct to large 200-ton storage bins. The is automatically fed into 5 Krupp six No. ball-mills, ore half will pass about crushed that through a 35-mesh so screen, and then whence led into a 400-ton bin, by through a 120-mesh, into feeders it is fed nine roll Edwards each treating roasters,
drier, the
15
tons
The
drier
ore
24 hours. per falls roasted ore
bucket-elevator,
separated by on through water
a
several
removed
;
copper-plates 100-ton
steel
vats
weeks, and *
The
mixer.
into
spitzkasten pyramidal spitzkasten
while
the
sands
and
and
of
pans. water, and
Ordinary
cyanide cyanide solutions as they
Three-hearth
Merton
to
pulp
slimes, have
from
The
are
are
now
off
being
are
used.
is
surplus over
the
centrates con-
sent
bottom-discharged occupies
come
a
pass
run
which
treatment
furnaces
which
the
sands
to
this
from
concentrates
Halley tables,
Wheeler
vats, drained the
a
is carried
and
push-conveyor
lifts it to
long ground in
below.
a
of conical
ft.
10
are
three
which
series
to
on
to
into three
returned
to
APPLICATION
OF
the
PROCESS
THE
IN
DIFFERENT
sands
which by an air-lift, constantly circulating. the spitzkasten thickened slimes from The the
a
of
top
tanks five pressure compressed air and
5|
of
set
with
13
x
cyanide
147
COUNTRIES.
keeps to
up
J ft.,where
they
solution
four
for
the
solutions
1 in
1 flow
to
agitated
are
hours.
One
is being emptied and the others being filled while another the The other. to one agitated working, the air passing from used for filter-pressed.Cyclone settling cones are pulp is then well air-lift for the pulp. an as settlingthe dust, as The oxidized Golden Horseshoe. is screened ore through the 2 in. grizzlies, 3 Gates No. coarser lumps passed through
tank
is
—
crushers, trucked
and
Challenge
to
1000-lb.
broken
the
wire-screen
woven
the
feeders
ore
The
stamps.
stored
ore
is
ore
the
at
200-ton
a
supplying
a
wet-crushed of
rate
passing
in
4
5
or
100-mesh
whence
it
is
50-stamp battery through a 24-mesh
of
bin,
tons
24
per
hours,
Free
gold is on amalgamated both inside the boxes and outside copper-plates, followed which of the are by concentrators Wilfley type. The sands in a series of are ground and amalgamated coarse pans and fine sands thus followed by settlers spitzkasten. The obtained 42 ft. lifted with fitted are by a tailings-wheel to vats distributors.
Butters
tables
of
The
fine
The
slimes nine
washed Excelsior then
are
slimes
elimination
concentrates,
etc.,
pumped
are
screen.
30 ft. over pass of fire concentrates.
sands, occupying
the
nine
or
collected
direct,
and
ten
days,
sent
to
of
is the
canvas
Double
practised. smelter.
without
agitators or montejus, carrying fifty 3 in. cakes, pressed, presses, and with and cyanide solution discharged. water, for clarifyingthe used which are solutions, gold presses are
each
Dehne
passed
to
acid
Sulphuric treatment
a
The
further
the
for
treatment
to
part
greater
of
four
treatment
zinc
the
zinc
slimes,
boxes.
extractor
with which
filter- pressing are
is
finallymelted
adopted for in a tilting
furnace.
battery is of 50 stamps, each 1250 lbs. The crusher, is brought by a Robins passing the Gates ore, after and crushed belt feeders wet to Challenge through a 30-mesh and lifted by a tailings-wheelto passed over copper-plates, screen, of grading boxes slimes series The supplying Wilfley tables. a overflow from the which the graders, together with that from the slimes Wilfleys, are lifted again to three hydraulic classifiers, tanks and the five sands to flint-mills which passing to settling then and the them elevated to crush to 220-mesh, are again The thickened graders and finallypassed to the settling vats. into steel agitators,agitated slime produced in these vats is run Stdphide
with
Ore.
cyanide
—
for
The
24
new
hours, pressed
in
six
5-ton
presses,
and
the
148
THE
Rich
Great
feeder
the
The
ore
with
lower
floors.
a
it is crushed
is
No.
a
30
floors,and
eleven
Sulphide
3 Gates
Robins to
is roasted
ore
for
conveyors
The
—
removal.
belt,
-mesh,
a
is treated
ore
crusher, deliveringit
and
then
Krupp large portion,especially to
two
100-mesh.
schistose, passing
crushed
high,
on
to
belt
smelters.
Reef. in
drying by breaking
ball-mills,where when
Main
Boulder
Challenge
a
the
to
PROCESS.
Robins
to
on
is sent
sulphide ore
without
by
dropped
material
waste
CYANIDE
in
Richards
a
shaft-furnace
65
ft.
rabbled
by hand, especiallyon the In furnace 35 tons treated. There per day are also each three Edwards of of 12 15 are furnaces, a or capacity bricked tons, which are angle. up to a constant The falls into a launder hot roasted ore carrying dilute cyanide solution, and is raised by a tailings-wheelto a spitzkasten. The sands but are ground fine in Wheeler containing mercury, no pans overflow another and continuous into with a plates, spitzkasten, the the slimes from while which the sands to again pass join pans, into These the first slimes, which vats vats. are agitation pumped 21 ft. in diameter and The 6 ft. deep. allowed vats to fill are are in 7 hours, the solution gaining in cyanide during the last foot of fillingfrom cake cyanide then added. 10 hours' agitation the pulp is discharged or run off into After in 3 in. cakes (Dehne). montejus and filter-pressed The clarified solutions are by passing through a small press, and led into zinc boxes. The washed, pressed, treated are gold slimes with in sulphuric acid, dried in a large iron muffle, and smelted Cornish
this
furnaces. Hours.
Dehne
fillingin, Leaching and washing Discharging, .
Four
the
ore
tous
per
ft.
x
10
Sulphides, 400-ton
There
bin.
65
day, by
is led
Ore
to
passes
ball-mill
—
.
.
.
.
.
.
\ 2|
in,
tons
View.
Lake
£ 1£
:
per
are
cent,
conveyors
ft., roasting
30
roasted.
ore-bin, four
to tons
and
four
per
thence mills
Krupp
of which
Gates
From
—
will Brown
day
pass
No.
by
with a
aerial
5
crusher tram
capacity
a
150-
mesh
of
to
0'2
per
130
screen.
straight-linefurnaces down
to
cent,
180 of
roasted is elevated into 50- ton ore sulphur as sulphides. The and is running, the 0 15 cent. KCy agitators into which per transferred the while into ten leaching vats, resulting sands are slimes to three on agitators for further agitation,before being pass Then follows zinc passed through montejus and Dehne presses. precipitationand sulphuric acid treatment.
150
PROCESS.
CYANIDE
THE
roasting, analysis shows cent. ; sulphur as sulphide, 0*32 sulphur, 3*60 per cent.
sulphur as sulphates, 2*82 per Total sulphur volatilised,0'46.
After
In
recent
a
Mr.
mine,
report
R.
the
on
Hamilton
;
Riecken
gives
at
process
the
costs
the
South
follows
as
:
d.
8,
2 crushing and transport to mill, 2. Fine pulverising,including proportion of .53 general charges and power, 3. Roasting and conveying ore, including proportion 7 of general charges and power, 4. Agitation with cyanide, and ejectrical precipitation
1.
Kalgoorlie
—
Coarse
7
per
.
J"
.
.
treatment, 5.
Filter-pressingand
was
average £3, 17s.
of
gold, equal
extraction
of
6d. to
ton, and
per
value
a
88 '4
.
JE1
value
lOJd.
for
10,318
of
ozs.
Diehl
at
an
11-81
per
ton.
£43,800.
Mine. s.
d.
9
5-6
.
17 .
.
.
.
.
.
development, Additions to plant, 46s. per
ton
.
.
11
3
6*3
30
10*9
working
1 3*9
approx.
Mine
Kalgoorlie Mine,
dwt.
....
process,
General,
2*125
1903.
gold, valued
View
Lake
Stoping,
March
ton, representing
per
38 tons
and
residues
of
„
cent.
per
Costs, February
11-098
7J
.
the
8s.
of
9
.
January, February,
for
ore
5|
""
.63
charges,
of the
value
Of
8 .
.
.
washing,
Total The
.
ton.
.
4*9 .
.
(higher
.
than
„
usual).
costs.
application
of
New
process
the
Wales
South
different
in
Filter-Press
The
following interesting details recently written by Mr. I. W. Rock.* details refer is one capable of dealing per
1. are
A
day.
of the
summary dry slimes
The
ground
up,
into
discharged cyanide solution
are
while
storage tank,
a
of
whence
The
200
into
a
paper these
dry
slimes
which
to
of
tons
follows
as
from
plant
with is
process
Practice.
extracted
are
151
countries.
:
—
mixer, in which added, the mixture
they
a
is
it is elevated 2.
flowing out-
into
agitator agitated for a
Mixture
centrifugal pump. by means mechanical period ascertained by experiment, by some means, thus between the metallic and chemical contact ensuring intimate iuto montejus, which consist of cylinrun particles. 3. Contents drical with inlet and and vessels also outlet valves, provided air compressor. 4. Forcing the connections of an to the receiver the montejus into filtermixture of compressed air from by means the gold-bearing solution escaping through the filter-cloths presses, vats
of
the
a
solid
the
while
presses,
material
remains
in
the
frames,
these further 5. cakes. forming large cakes by "washing" or forcing, at a high pressure, a weaker of solution cyanide through them, and, if found a necessary, second washing with water only. 6. Getting rid of the exhausted and slimes discharging the cakes into by opening the presses them 7. Clarifying the to dump. a tracted extrucks, which convey the from them solutions flowing by running gold presses, thence them sand into into and tanks, pumping through traps obtain and elevated to tanks, in order regular pressure, passing in order them retain to through a finer class of filter-presses, any which would foul the zinc extractor boxes. impalpable solid matter the the into boxes 8. Passing the outflow from extractor presses the outflow usual and treating therein in the being of manner, for strengthening and returned to sumps re-use. course article These made standard Mixers. are a by the as meter engineering trade, and consist of a steel cylinder 6 feet in diainserted has which an by 5 feet deep, lined with cone, outside the and the in it of the at shell, near openings top vertical mitre four-bladed bottom a shaft, with a propeller on The wheels and driving gear. propeller not only cuts up the thin
A
extraction
from
—
slimes
and
upwards
the
through
overflows
into
Agitators. diameter, open —
the
*
Rock,
at
solution,
tank,
consist
the
connect The
the
openings
storage
These
which
openings
with
them
mixes
on
of steel
top, and with
Australian
and
with
both Mining
up
it drives
but to
its way
the to
the
the
mixture
outlet, whence
it
agitators.
high and 8 feet the lower portions tapered to outlet and circulating pipes.
vats
16
Standard,
feet
Dec.
12, 1901.
152 To
THE
sole
whose
With
or
arms
it into
and
the
them
bringing
efficient
the
draw
to
redeliver
particlesand highly
is
duty
and
bottom
is connected
agitators there
of these
each
PROCESS.
CYANIDE
in
paddles adopted
mixing
time
the
found
been
has
contact
compared agitators previously
regard
to
horizontal
in
of
the
from
vat
mode
This
intimate*
economical
the
of
contents
top.
into
centrifugalpump,
a
as
adopted. Centrifugal Pumps.
These
—
the into elevating the mixture with material for dealing gritty usual as
chambers
water-pressure would
water
dilute
the
and
cyanide solution under tank, supplied by a small pump.
the
have
glands, but proportion, they from
pressure
used
ones
the
the
upset
for
one
They
process. with in connection
mixture
the
only
the
in
with
fed
are
and
circulatingpumps, agitators, are the
elevated
an
large enough to receive the contents of an after the style of a compressed-air receiver, agitator,made Inlet and buried outlet valves, of vertically in the ground. chemical and grit-proofmake, are fitted on them ; compressed-air fitted on are supply and exhaust, test cock and pressure gauge, In each. addition, there is a small air-agitationconnection, so and that any mixture for time in one is kept alive a remaining the deposition of solid matter prevented. These after the Filter-Presses. are generally made by or the German size having engineer, the usual pattern of Dehne, frames, the total contents fifty 40-inch x 40-inch x 2-inch being 75 cubic Jn the addition feet. to fittingssupplied by makers, Montejus.
—
These
each
are
—
there
such
the
drip trays,
as
minor
others
several
are
Of
trucks
Solution
drive
the
course
have
discharge
of the
here
washthat
contents, out
any
for
This
—
with
cast-iron
the
montejus
water
100
at
both
added, other
several
and
launders,
be
to
for
snoots
delivering into in
the the
them.
Pump.
pressure pump the presses from
the
leak
and
spent slimes, as they fall out of the frames beneath, form part of the setting of the presses
Wash
noted
necessary
of
building prepared
that
are
and
slimes
accessories.
cakes
which
be
may
be
air
The
at
up
and
presses
to
inch.
square
admitted
for
pressure
reckoned
lbs. to the
is
descriptionof high-
of any
fittings.
fillingthe
after
compressed
may
for
a
filling 80
lbs.,
It may
washing
after short
be
period
to
moisture.
These also but of are a Clarifying Presses. filter-presses, much the frames of wood. lighter description, being usually made flow of the They are supposed to be self-cleansing,by reversal with materials, but other slimes through them, and are so some it is of that found to have set are so gluey a spare necessary —
filter-cloth frames,, which
can
be
substituted
for
the
foul
ones
in
APPLICATION
a
PROCESS
THE
OF
DIFFERENT
IN
153
COUNTRIES.
and scrubbed. minutes, the latter being taken away the delicate, and are pulsation of a pump very
few
presses their
efficiency.
solution
into
through
the
The
It
tank
a
of
specified,and
18 thence
hardly be compressed
power,
whence
high, the
to
destroys the gold pump it flows quietly
to
necessary
feet
boxes.
extractor
etc., need
storage vats, sumps,
it need
steam
therefore
and
presses,
items
is about
added
These
be
not
particularly cient suffi-
the
adjuncts of supply of water
that
air, and
are
necessary.
Practical
Work. the
ordinary work, tipping trucks
If
—
plant
a
would
routine
are
delivered
of the
agitators
described
above
as
be
further
as
doing
is
described.
its
Side.
regular intervals alongside the mixer, and the contents dipped bodily out, the fall being broken to by a shoot, sufficientlyflat to require the attendant use a shovel and in some the feed. He also, through degree regulate knows much how in from solution to run practice, a cyanide that flow of mixture into constant cock, so supply a fairly escapes the
at
storage tank. When
and
one
the
elevated
storage tank,
is
empty,
centrifugaldoes
this
is
signal
a
in
minutes
few
a
the
given
all
refill,
to
the
from
time. circulating pump running the the in of man agitation, charge machinery room the inlet valve and the air of the fills one montejus, opens escape the cock being open. When in he closes the charge is all run inlet valve and the little agitation cock until he receives a opens be that is When he that he filled. to closes a press signal gets the above, opens the the outlet and then valve, compressed air After
the
sufficient
cock
; the
of the
contents room one
pressure
In
the
water
time
into
thereafter then
at
once
Notice
matter.
open wash
been
the
room
the
start
outlet the
stopped,
a
wash
main
the
on
until
to
a
gold sump
in the press given when any reclosed, ready for
press valves
taps
are
directed
re-use.
and
open,
the
solution
for
the
the
are
close the
to
pump; flow therefrom
as
leading
little air blown
and
the
the
was
half
minutes to
frames
them
given
the
launder
fill
emptied
water
few
a
transferred
from
is then
opened,
same
into
flows
in
signal to
had presses the cocks outlet
filling. gold solution and
this
has
been
All
solid
montejus
above. of
rises, and
gauge
ran
the
is full
of
previously closed, for
a
the
little
into,
Pumping
and is
through to complete the process, and the press unscrewed, the drip trays being previously removed. One after another the dummies, the as are slimes-bearing frames the cakes either fall or are called, are pulled forward, pushed out into the trucks each frame is clean with below, a scalpel, scraped and the press tightened for fresh a charge. up again The of the gold solution treatment is pretty well automatic ; its a
154
CYANIDE
THE
through
flow
PROCESS.
the
clarifying presses has been already described, of the extractor-house. delivery into the zinc boxes It will be understood in no that the diagram indicates way any of the plant. Accessibility and ample space arrangement are and details of the particularly necessary, some plant which are from the makers purchased as articles ready for use require con-, and
its final
siderable
alteration
Other and
in
States
the
Queensland, for
the
except purposes of the m
charcoal
the
cyanide of
has
Victoria, instead
them
suit
Australia.
treatment
tailings. Nowhere in
make
to
any
where
This
process sands
is
above
requirements.
Victoria, is
and
distinctive
precipitationprocess
chlorination
In
—
charcoal
of zinc.
the
South
employed old feature
Australia,
almost
accumulations
ively exclusof
been
developed used is much for precipitation survival and really a adaptation Victoria in formerly employed
process.
UNITED
STATES.
The
in the states cyanide process has been successfullyintroduced of California, Colorado, Idaho, Montana, New Utah, Nevada, and and Black Hills Dakota. Mexico, district, South Washington, the the of in the has States Generally speaking, adoption process been for this the due to slow, the primary cause being doubtless The of the ores. of the ever, howcomplex character process, progress during the past year or two has been very marked. The is one difficulties, presenting many especiallywith process base and the time to ores sulphides, containing present up American have been feel their safe content to metallurgists on way ground. The the same lines as where, elsecyaniding of tailingsis conducted on while the slimes problem seems have been to successfully solved by the adoption of agitation followed by decantation. of the The treatment of sulpho-telluride ores Cripple Creek districts by cyanide after roasting has much been with attended silccess. precipitation of Up to the present time, the electrical has had little or gold from cyanide solutions application on a no For the treatment of high-grade slimes, there working scale. may be for the filter-press practised in Western possibly scope process
Australia. The
day,
and
largest in in the
read
Homestake
new
the the
States
with
much
tons a plant, with capacity of 1200 per the of 600 tons Smuggler-Union are day, among per States. Actual working details of cyanide treatment seldom will be available, and the following notes are
interest.
APPLICATION
OF
Colorado.
Godfrey cyanide small
for of
treatment
155
COUNTRIES.
DIFFERENT
I am indebted to Mills, Ouray, of the instructive particulars following this The mill. at a tailings contain tailings Bird
Camp
—
Doveton
IN
PROCESS
THE
—
the
led to
of copper, has which of the usual interestingmodifications
percentage
the
adoption
of
some
Doveton
practice. Mr,
says
feature, but as much tailingspresents no new the of the gold is partiallyenclosed in coarser particlesof sand, a rather is required. lengthy treatment The tanks are charged with Butters distributors, and the slimes three slime from overflow gates placed at the sides of the vats, the
of the
treatment
and
conducted
are
preferred to is
to
the
circular
a
effected, a
A
sizing test following results
dam
slime
launder,
better of
a
as
somewhat
a
of
ore
wire-wove
On
to
bullion
are
the
showed
—
99-05
in
batteries
stamper
through
a
35-mesh
screen.
the
assay,
found
tion classifica-
:
crushed
was
gates
better
samples
vat
Total The
Slime
result.
is the
leaching large number
settled.
and
and
found
material
button of the
was
very
much
the
than
considerablyhigher
run
finer
40
the
on
that
than
and
finer
60
meshes
was
material, and resulting from
the
the
finer
product. sampled at the distributor nozzles as a check upon filled the charge is also the vanner tailingsat the stamp mill. When 40 to 50 bores sampled with a borer, some being taken from a 500acid is made An ton on vat. acidity test for free and combined and lime is of the head the found, and sample, requisitequantity the added of the on top charge, and well mixed by shovelling over top layer of material. tank The Details of Treatment being partially Charge. of 100-ton
assay
The
vats
are
—
drained
and
lime
added, 0*05
containing
about
contains
considerable
a
per
20
cent.
a
KCy.
percentage also, owing
cyanicides, and of the cyanide, dissolves much in material the thereby leaving for the
of
tons
This
solution
are
better
on, also
run
solution, which
of copper cyanide,acts of much to the presence
copper a
weak
contained condition
in for
as
the the
a
food
cupro-
charge, actual
156
weak
It should
saved
gold of gold
the
as
and
off
on
is amenable
rare
by the first immediately
available down
run
liminary pre-
cyanide sluice
the
etc.
occasions,
when
from
10
treatment,
to
the
by
rule
a
of the
sluicing purposes, that
is removed
as
whole
drain
to
for
mentioned
be
contents
value
and
is allowed
destroyed, it launders, to be
is dissolved
gold
solution,
is
of the
No
solution.
working
PKOCESS.
CYANIDE
THE
portion
a
25
to
cents
solution.
of by a succession until 10-ton the outgoing charges of solution of 0 25 per cent, free KCy, solution rises to about 225 0*20-0 cent. KCy. Usually per and 60 of solution, the time the tons run are by outgoing on, standard solution 65 is up 70 of to to cent, near strength, per the The allowed macerate to gold is dissolved. charge is now from 8 to 16 hours, and is subsequently rapidly drained, sampled, and below shovelled for the second treatment. to the tank During the the and has been the assayed, gold shovelling charge sample almost all the of ascertained. extraction Usually yet capable soluble compound has been carried out by the charges of AuKCy2 Should much the show that of the solution. previously assay insoluble solution the is standard in gold still remains ore, added Should in the lower the be vat. unusually gold contents the 0*4 solution for is used saturation cent, high, 0*3, 0*35, or per of the shovelled has charge. If, however, a fairlygood extraction The
weak
solution
is
followed
'
in the
obtained
been and
when
we
are
immediately Mr.
from
6
to
washes
the
surface,
all
ensures
The
added
the
solution,
boxes, and at
the
40
time
cents
waste
about
usually
thence of
the 12
of
weak
dissolved drained
now
values
of
applied
the from
and
is
mill. weak
much
of
to
and
waste
zinc
waste
this
is
This
washes
water
The
the
the
out.
passed through The gold value to
below
hours.
two
cent.
per
tank
cent.).
per
disappeared
macerate
0*04
couple of partially
a
(O'08-O'l25
gold being carried dry on surface,
gold cyanide,
of
out
apply
to
macerate
to
each, drain
tons
has
to
allow
and
solution
fall to
in
10
washes
weak
low
ton,
rapidly,
allowed
is
transfer
per
zinc
"At
tons
the
from
drain
weak
the
used,
practice is, however, and
solution,
solution
the
usual
Our
—
cent,
then
charge of
"
:
cent,
of
charge is till cyanide
transferred and
last
is
saturation.
per
hours,
per give 25
the
Before
"
0*3
of 0'3 and
with
continues
with 4
dry,
after
Doveton
saturate
the
solution cent, per washes are tailings weak
vat, 0*25
upper crowded
liquor is now gold tank, the
waste
of the boxes
precipitated
zinc
solution is about in
the
boxes. time
per contains
of
sluicing,the
cent,
about
of
charge
moisture, and
0*02
per
cent,
is
fairlydry, containing outgoing solution free KCy, but only a
the of
158
CYANIDE
THE
PROCESS.
the bullion, along with promote the precipitation of the copper solution the with thus becoming overcharged preventing copper. last fresh the of after zinc in Occasionally, placing compartments with in about the boxes, it will be eight perfectly coated copper
or
the
because
hours,
two, is very
gold
the
will
Should
"
the
of
into
gray
in colour the
bullion
of
of
is allowed
which the
the
deposited
will
mercury continued, is dis-
solution
black
become
to
becomes
zinc
mercuric
zinc
Winchester
few
a
When
of
the
Cu,
the
of
partiallyout
usual
boxes
the
boxes
was
from
solution
0*045
as
dollars
per
lift the
to
as
tions solu-
occasions,
5
or
bullion
good
the
much
as
4
great
so a
should
several
on
contents,
however,
;
and carried
bullion
hydrogen
of
increased,
usual,
the
entering
and
is much
than
copper
more
evolution
the
hydrogen
of
solution
the
ton,
hours
few
a
precipitating bullion,
of
signs
addition
the
zinc,
evolution
cent.
per
the
use by cyanide solution,
mercuric
coppery and in
contain when
of 24
course
precipitate.
The
"
compartmetit
entering the boxes, precipitate being a
is
the
affected. compartment the from amalgamation
the
drip with
last in the
However,
no
aided
readily
strong
show
zinc
coppery
precipitation is quarts
value.
the
black.
lustrous
very
it reaches
perhaps a higher bullion value be the plated over copper,
when
hours,
when
solution, in bullion
low
zinc
precipitation only 5 grains recently, when
worth leaving the boxes of noticed this ton. of gold per was example solution the of showed a working a complete analysis presence of about small 0*00778 of cent., quantity a manganese, per the evaporation of 2 litres of solution estimated on by Volhardt's lime No method. found, but was sulphates or magnesia were
obtained, the
was
An
the
present
to
found
little
a
large
lead, of
amount There
cent.
could
be
not
here,
agent
little
The
valuable,
seem
alkaline
no
"
yet
that
when
sulphide from
is
frequently
of Threshis*
iodimetric
oxygen
as
latter
the
but
present,
has
sulphide
it enables
sufficientlyaerated presence
iron
of
ferrocyanide,
no
0*1078
about what
in
was
but
a
per
combination
determined.
precipitatedas sulphide "
alumina,
There
Ca.
of
cent,
per
considerable
a
it would
and
0*01387
sulphocyanide,
was
alkaline
"No
of
extent
of from
or
2 to and
Experiments of employing merit
to
us
7*36
of
the
as
the
solutions
the
zinc
precipitating being readily
ZnK2Cy4.
estimated
in the
method. ascertain
mgrms.
numerous
jets
exist,
of
solution
The
our
tests
oxygen
oxygen
estimations
compressed
per were
air
by
in
the
fication modi-
solutions showed
litre of made
a
is
estimation
whether
Numerous
not.
in
is used
zinc
can
the
detected
been
to
very are
the
solution. test
sumps
the
and
APPLICATION
OF
should
storages,
THE
to
the
during leaching vats.
of
the
the
little
more
weak
per
solution
noticeable
Here
the cent,
of
the
that
total
KCy
weak
0 4
only
Bird
Gamp
gives the treated, including 2*4 of gold slimes. Doveton
last
erected
year. precipitation is used. Pneumatic
Dorcas
charges
cents
per
It
has
and
120
interest,
as
compressed
solutions
and
pulp
is extracted The and
rolls
coarse
and
*
20
the
through The
a
air
mgrm."
of
Mill,
tons
Florence.
The used
is
600
treatment to
and
aerate
dollars
in
sampling
Engineering
sets
and
of
room,
Journal,
has
plant is of
a
some
agitate
the
crushers
through through
finishing rolls
Mining
was
Zinc
tion following descrip-
value,
passes thence
mine
day.
per
here
ore
treatment
this
This
—
of
ton
acid
at
The leaching vats. by Dr. Wells.* paper
two
dissolved
of
per
sulphuric
the
in
from
to
for
capacity
day.
per
averaging
ore,
dryer
tons
0*11
Mills,
3s.
cyanide plant
The a
about
as
ton
Cyanide
of
capacity
being boxes.
71-57
total
—
a
Tailings monthly.
tons
Mine.
Union
time.
zinc
KCy litre
per
contained
at
the
very that
of
increase
cent.
per
a
contain
Total,
Smuggler-
majority
to
the
leaves
mgrm.
Treatment
of Cyanide 5000
boxes
zinc
the
in
average,
strong,
0'08
0*64
solution
strong
on
solution
containing
contained
the
the
than
the
solution
Cost
found
we
found,
oxygen
when
the
end
of
was
weak
while
oxygen,
passage
cient insuffi-
received
solutions
the
from
dissolving but capable were the aeration, and greater portion again on standing for any length of
on
dissolved
more
most
the
that
However,
diffused
was
"The little
their
159
COUNTRIES.
DIFFERENT
solutions
oxygen
dissolved
IN
found
it be
oxygen
cases
PROCESS
Jan.
which
4, 1902.
a
ing revolv-
crush
it to
160
CYANIDE
THE
2 4 -mesh
The
size.
PROCESS.
finelycrushed the
hoff-Wethey furnace,
is then
ore
roasted
roasted
in
to
the
4*5
ft.
product passing
Holt-
a
leaching
tanks. There
fitted
are
with
six of these air
tanks, the
in
pipes leaching.
30
diameter,
ft. in
bottom
the
for
and
deep,
introduction
of
air
The air is supplied at during the a pressure 1 cubic air about of 5 foot minute to each lbs., exceeding per of ore being sufficient for agitation and oxygenation. The treatment generally lasts five days, and leaves a value about
1
treatment
the
40
filled
by
is run ton KCy per flow in to continuing turned on gradually, and least
90
through
the
of
at
iron
rods.
then
shut
and
conveyor,
pulp a gradually,
in
until is
the
kept the
charge
ore
sluiced
is then
soon
as
the
until
this
bottom 10
air
then
is
tion extrac-
an
comes
stirred
be
air
shows
lbs. time
same
The
pulp the
to
the
at
full.
the
has
the
as
containing
pulp is
Whenever
cent.
per
of
tailings after
solution
tank on
The
ton
ton.
per
with
is covered
tank
tables.
cents
a
residue
The
ore.
Wilfley
on
about
average tanks are
The
ton
per
the
in
concentrated
and
out
of
dollar
not
evenly un-
up
by
with
men
This
The air is 30 hours. generally requires about the allowed settle for hour. to one pulp off as Percolation is then run begun and the strong solution of 5 lbs. KCy one quickly as possible,followed by a weaker per of the solution This until the tests ton. operation is continued is then of added show to gold. Water displace only traces less than solution. The loss in the is be stated to KCy cyanide dust the The 1 lb. per ton. dry-crushing is resulting from and treated with collected cyanide, without previous roasting. From dust assaying 51 '20 dollars per ton the tailingsonly contained It is added in the leaching 80 cents roasted to the ore per ton. each of the charge. tanks, 3 tons to tank, spread evenly on top and
off
Cripple
Greek
district
is andesite
On
surface
the
gold
occurs
associated
the
oxide
more
or
the
in
of
calaverite
less with surface
gold amalgamation, being coated easily extracted by cyanide. dead The
roast
reduction
instead pass
telluride
unoxidized
The
of the
through
a
ores
used
40-mesh
and
carry Below
iron
this
of
granite. peroxide,
water-level,
sylvanite,and
is
the
always
pyrites. is
free, but
not
with
metallic
oxides.
ores
have
be
to
amenable It
to
is,however,
subjected
cyanide is generally effected ore at Kalgoorlie, the ore
before
of the
mills
iron
decomposed
and
tellurium.
rock
country
and
oxidized
are
ores
in the. minerals
The
The
—
breccia, phonolite,
oxide, and
manganese
Practice.
Telluride
to
a
liminary pre-
treatment.
screen.
The
roasted
with
Krom
being ore
rolls,
crushed
is leached
to
by
APPLICATION
THE
OF
PROCESS
percolation in vats with 0*5 to containing from allowed to percolate for is added.
The
The is
effected of the
treatment
obviously a
0*75
hours,
varies
with
the
stronger,
weak
70 to
from
is
solution
100
hours.
zinc*
sulpho-tellurideores problem than
difficult
more
The
potassium cyanide,
of
which
after
161
COUNTRIES.
cyanide!
of
cent,
per
of treatment
time
Precipitationis
solutions
two
50
DIFFERENT
IN
Australia
of Western that
of
Cripple
Creek
At
Kalgoorlie, the ore is talcose and is highly calcareous, and forms so large a proportion of slime that ordinary percolation is impossible,and deoantation slow and too ful successcostly. The found in the use of filter-presses, solution of the difficulty was in which the dissolution and of the gold is effected under pressure, of which the slimes are the by means goldeasilyseparated from containing solutions and washes. ores.
As
at
Cripple Creek, the oxidized the undecomposed ores
state, while before
cyanide soon recognized
was
better, and
to attain
into
come
has to
20-mesh
1000
of
size and
in diameter Zinc
that
and
tons
adoption
Mines.
in
The
—
The
day.
per
treated
then
5 ft.
raw
dead
a
roast
of
use.
California King
—
capacity
a
that
general
California.
to
the
in
it filter-presses, the the greater the proportion of slimes object, pulverizingmills,instead of rolls,
treatment.
have
subjected
are
the
With
treated
are
ores
ten
deep, provided
with
ore
plant
this
at
is crushed
mine rolls
by
cyanide vats, each 40 ft. bottom-discharge doors.
precipitationis used.
There
are
many
State, including Golden
Cross
the
Mines
the throughout cyanide plants scattered the of large 140 -stamp cyanide mill these at no Hedges, but particulars of
available.
are
Montana.
in this
progress of them The
of
State.
that
says
Many
In
cases
the
ores,
the
Nevada.
—
carried
as
process
amalgamation slimy
Wells
cyaniding
plants
new
have
made
has
been
great
erected,
some
large size.
elsewhere.
other
Dr.
—
of
many
on
the
this
in
mills,
plates, followed
on
is crushed
ore
State the
in rolls
sun-drying
method
by cyaniding and
practice is to agitate and The
is much
slime
is of
cyanided
the
same
as
wet-crushing, tailings. In direct.
With
decant. treatment
adopted
Dexter
at
the
referred has to in the plant at Tuscarora already been the other Of slime treatment. chapter dealing with plants in in this while others State some are operation are treating tailings, dealing directly with dry-crushed ore. has a successful of Bland New The Mexico. Cochiti Company —
*
Prof. Furraan.
Mines
and
Minerals, January 1897. 11
162
method 98
CYANIDE
THE
of treatment
used
of the
cent,
per
steam
steam
bottom
Steam
is used
100-mesh
a
pass
heat
to
cooled
air and
of the
escape
total
values
in
are
The
much.
solution, using
lbs. per ton, but only 80 per cent, solution going to waste in the slimes.
in
and
ore
wire
a
is
Utah.
—
the
of
There
ore.
recovered,
To
neutralize
the
under
per cent, of
cyanide due
the
to
acidity suspended
is The
of the
of
cost
has
ore
to silicious
in
the
much
sinter, or cellular
as
serite,
gey this
in
is considered in
capacity
a
described
been
abundant
district,cinnabar
realgar occur
cyanide process
plants having
is most
as
the
the
tank.
centres
Mercur
similar
is about
in
94 of
that
and
in the
hours
24
-lb.
ton.
incrustations
and
in. holes
by
of air
pipes
solution
a
different
Cinnabar
in the
Orpiment
gold.
of the
greatest
form
ore.
found
Wherever
per
of the
day. a
beautiful
forms
dollar
The
mixture
is
of
part
States, the
process
slimes, lime
upper
one
per Silica in
"
:
settlingof the
1
as
is
tons
characterizes and
the
given
2000
t
in
United
in the
follows
the
Mercur
—
over
aid
basket
treatment
of
to
The
iron
In
steam.
3
of the
Here
agitation being effected latter 60 being under found charge, as it was
the
it too
features.*
screen.
expanding is admitted through 1 in. horizontal of the tank. The pipes have 0*0625 on
side for the of the
will
dust
novel
some
possesses
agitating and settling,the and air, the compressed
is
pressure. the air
which
PROCESS.
rock,
varieties. a
sign
sure
in
some large quantities is usually found as
iron
in
and impure limestone clay. Barite and gypsum more or occur also mineralized found of limestone crystallized: masses are in rings, the outside from the 6 dollars 8 to dollars, and assaying No in gold. trace free gold is visible centre in the a even ore, with feature absence of remarkable is the a microscope. One The of the ore silver. milled is kept close to 1 2 dollars average less
per
ton."
At
40
ore-bin a
Mercur
the
Dodge
ft.
crushed
is
20
ft.
and
wide,
bottoms. four
15
The to
or
They
filter cloth
six weeks.
ft. to
the
to
less.
tons.
20
it passes
finally trammed
hold
from
is delivered
ore
which
from
1 in. mesh
to
and
lasts
the
long,
crusher,
rolls, and
mill
vats
are
made the
From
set
a
are
of
false
the
tanks
railroad
vats, 12
ft. 8
in.
Hunter,
t
Mining
Engineering and
and
Mining
Press, May Scientific
meter, dia-
wood red-
burlap,
and
iron,
bottom
is
Journal, Jan. 23, 1896.
in
with
solution
a
*
in
corrugated being
it is pumped which collecting tank, from by The the zinc to single-acting pumps precipitating room. from 24 12 about to 36 in. wide, 10 to in. deep, and are long. to
an
after
tank
the
to
is crushed
of Walls
cyanide
The
on
by the deep. It
19, 1901.
is
veyed con-
Blake boxes 20
ft.
APPLICATION
Fine
is found
crushing and
porous,
PROCESS
THE
OF
be
to
163
COUNTRIES.
the
as
unnecessary, mud
disintegratesinto
of it
much
DIFFERENT
IN
is very
ore
when
solutions
are
applied. in Mercur It is interesting to note one change made practice. solution the ously, continuwas run ore Formerly the strong through Now surface series of the a being kept always covered. washes is run time below being down through, the solution each extraction been the has increased The surface. thereby, and much
at
was
At
the
has
the
of his
strength At
the
within
notice
by its alkaline feel. practised. Still an operator determining
an
wholly by their odour. formerly practice was
solutions the
end by adding cyanide to the lower judgment of the operator determining the
solutions "
the The
slimes
zinc
mill.
amalgamating 160°
about
taken
C. the
This
table.
present dollars, giving as
80
c.
dollars
\
Mining, cyaniding the
;
:
50
lb. per
Golden
TJie
best
constructed order
hoisted 420
in to
on
ft.
in
length
from
which
2
are
stone
behind
85
per
of
The
ton.
ore
for
cost
refining. about
and
cost
is at
cyanide
top
ft. wide
50,000
over
*
1*75
ore average itemized is
hauling total
complex finally
sheet-iron
a
on
of treatment
c. per ; railroad 1 dollar 35 c. ore,
of
are
assay The
cent.
ton
a
milling, 2
ton,
per
present about
and
800
ft. and
up
the
top
long. down
bottom
to
a
is
top, and
States.*
hillside
of
said
are
United
on
the
to
ore
at
built
are
These
—
the
with
it
is 294
ft.
The
mill
slope.
145
ft.
The
a
batter
have
has
Excerpt
were
levels. to
wide,
be and
difference
The
in
retaining walls, of
cb.
from
the
be
They eight
works
the
to
1
ft. in
The yards of rubble masonry. constructed were by blasting out the side hill. The for the used thus obtained was retaining walls and The mill is driven them. transmitted by power
required floors
dollar
consumption
the
incline
elevation
12
Cyanide Works. equipped in the
1898,
get
an
of
slimes
at
ore.
Gate
and
largest In
of
ton
a
—
The
cents.
from
per
35
fumes The
the
to
luted, and
not
burning completed shipped to a smelter
extraction
an
6 dollars
is about
follows
a
boxes,
amount."
belonging
but
headache.
zinc
and
time
retort
is closed
standardize
to
the
of
the
residues
the
value
and
is then
product
At
old
an
product ignites,producing
retort, and
the
from
in
door
The
salivation
causing
nature,
dried
were
strength. strength of the
the
are
of
in
per cent,
and
boxes, methods
our
mill
Mercur
0*3
to
estimate
to
zinc
acute
more
come
cent,
per
practice
in the
time
present
instance
the
its action
by
vat.
O'l
is from
time
one
solution
each
on
used
solution
The It
saved
time
Bosqui's Cyanide Process,p. 174.
12,
various broken
filling electri-
164
THE
cally
distance
a
of
miles
35
at
of energy in transmission At the works the 40,000 220
of
volts
price contains
the
third
the four
which
furnaces,
150
One
attends
furnaces which
connects
hill
the
on
department,
by a
floors,the
talcose
the
main
The
level
of
building. 7, is 60 by
the
section
constitutes
top
ft. high,
this
stack
The 294
the
chamber, 85
of
rated
from
dust and
in
have
minute.
carried
are
into
four
are
each
lift
ing roast-
to
ores
once
gases
buildings.
the
lowest
which
are
In of
a
the
estimated
rabbles
The
ft. flues
8
with
contain
steel stack, 8 ft. in diameter
above
the
ft. above
275
6
with
elevators,
for
the
by
furnaces.
two
to
through
located
is stirred
ore
ores
mill
Berthelet
straight-linedesign, those
tract con-
consists
36 -in.
sections
for arsenical
tons, while
75
of
The
tons.
man
are
sixth
Brown's
of
six
are
a
dryers.
which
of
sets
There
sizing.
intended
Those
daily capacity
at
for
three
to
the
of
the
are
crushing machinery,
fourth, fifth,and
The
ft.
fine
at
first section second
The
5 per cent. is transformed
delivered
is
The
in the
rolls, and
-in.
used
are
number. a
is the
26
of
sets
60
crushers, and
coarse
only
current
H.P.
per
be
to
volts.
40,000
3-phase current
The
2-phase.
dollars
section
apparatus of
of
60
of
volt
of
tension
a
is said
loss
one
PROCESS.
CYANIDE
is
leaching It has
ft.
25 by 50 ft. and supporting ten tanks and tanks three solution 5 ft. deep (presumably rectangular), 20 ft. and The tanks 12 ft. deep. in diameter are supported by masonry from hand cars run charged by on bridges over piers. They are the which The section of 50 the tanks. is mill, eighth by 70 ft. and stories in height, is the It two precipitation department. 14 contains three and ft. in diameter precipitation tanks, each the tanks The from 8 ft. deep. are leaching tailings discharged the The which waste to into run dump. are building is concars structed two
floor
main
of steel.
Dakota.
South
extracted
practice are
M.E.,
Fulton,
from
the
to
following details
The
—
cyanide plants contributed by Mr. Chas.
paper
a
and
Engineering
of
and H.
Mining
Journal,
January
Tailing
Plant
Lead,
4, 1902. The
plant Highland plant in a 10 and
classifier
eight large
no
upward
at
the
carried
stamp where
to cones
The
slimes the
and
sands
On
of the
but
settle
overflow
as
to
is
Golden
conveyed
the
are
ore
pulp
bottom
the
periphery. cyanide plant, where they are treated
at
as
above
described.
—
Star, Eighty, to
the
These
classifiers.
the
at
cyanide it passes through the separated by means
its way
slimes
cone-shaped
rising current,
or
pulp
pipe.
some
sheet-iron
centre, the the
mills.
the
from
tailings pulp
in. cast-iron
house,
of
while
the
takes
This
1200-ftm
Company's
Homestake
is
and
The fed The
cones
have
charged by pipe are discharged, sands to
are
seven
slimes
then tional addi-
overflow-
166
THE
between
spaces Gates
the
to
go
into
bars.
7
screen
long,
ft. the
through
elevated
by
finishing This 2
The
ore
leaching deep, tank
and
of
is
used
has
half
hours,
are
run
then
is
it
drained,
After
it. short
this
time
The About
solution
50 of
tons
wash
from
by
85
results
90
to
per the
of
cent,
amounts
in
presses,
by
the
the was
difficulty in
\
about
to
treated
values,
usual
tanks, tried the
lb.
and
the
at
the
clean-up.
acid
the
having made
is
ore.
method.
discarded
The
6
and
give before
mixture on
is
accomplished
and
good
very
value
of 80
from
from to
dust
are
tion precipita-
through account
90
cyanide
the
precipitates
Zinc
9
to
cyaniding
is
a
a
ton.
per
added of
of
consumption
resultant
mill, but
cost
replace
leaching.
ore
are
barrels,
solution
of
ton
per
the
6
stand
from
by
precipitation
extraction
sulphuric pumping
The
is
hours,
cyanide
ton
per
is
solution
to
the
a
tank
to
top
of
of
and
four
to
lbs.
veyor con-
two
strong
followed
constructed
tailings
of
ft.
capacity
the
allowed
acidity
7
solution
at
is
3
to
bins.
The
The
ton.
lime
of
ton.
the
the
to
balance
used,
are
first
specially
in
cents
lbs.
the
per
obtained,
are
10
to
6
into
cents
thread
zinc
per
dumped
is
ore
alkalinity,
J
two
three
it
the 2
neutralize
To
water.
protective
the
solution
weak
of
tons
from
contains
the
added
being
for
mill
strong
stand
four
100-ton
large
after
lbs.
15
replacement
circulated
then
which
in. belt
A
the
the
About
solution
complete
and
weak
weak
a
the
of
the
into
16
a
added
of
to
all
ft. diameter,
16
from
in
being
allowed
usually
and
long
from
bin
minute.
charged
solution.
ing shakrolls.
ft.
Nearly
purpose
gives
strength
coarse
oversize
is
this
solution The
of
ton
tank
which
are
the 16
product
ft. per
added,
cyanide
and
finished
For
to
rolls.
finishing
600
Tanks
per
on,
of
the
product the
mill
screen,
stationary. screen,
the
the
with
J-mesh
fir; each
been
filled.
one-half
cyanide
to
from
speed
a
the
lbs.
4
at
the
capacity.
tons
above.
about
a
55
being
Oregon
of
2
6-mesh
a
level
a
passes tions revolu-
100
at
combined
the in
2-mesh
which
in., operated
elevator
revolutions
80
from
undersize,
feeders
inclined
stationary
a
oversize
on
Tulloch
in.,
the
from
ore
by
24
by
24
shaking
passes
recently
mentioned
the
half
charged
tanks
by
situated
lower
14 to
one-bucket
by gravity is
14
meets
it is fed
the
wide,
inclined
product
is returned
rolls
crushed
the
which
from
rolls
the
an
the
wide,
finished
ft.
screens,
is
screen
ft
1
and
and
discharge
fiuishing
minute,
per
being
rolls
PROCESS.
undersize
Gates
coarse
The
minute.
per
The
storage bin,
of
set
one
CYANIDE
filterof
the
APPLICATION
OF
THE
PROCESS
BRITISH
Athabasca of
meeting Mr.
1901,
the
In
—
American
Nelson
E.
167
COUNTRIES.
COLUMBIA.
Nelson.
Mine,
DIFFERENT
IN
a
read
paper
Institute
before
the
can Mexi-
Mining Engineers interesting information on
Fell
of
in
gives some The consists of a tailingsat this mine. ore, he says, containing a little lime and variable quartz gangue, quantities of the sulphides of iron, lead, and zinc. The following figures,giving the analyses of the before of the tailings after ore milling, and the material constituted based to be milling, which cyanided, are the daily samples taken on during February 1901. the
of
treatment
Ore
Analyses of
and
Tailings.
Zn,
Fe, Pb, CaO, S,.
A1203, SiO 2"
Au,
Ag, analysis shows
The
this
be
to
well
ore
an
adapted
for
cyanide
treatment.
The
plant
mill,
in two
height.
The
rim, and
are
while
the
A
tanks
filled with
overflow
10
in.
positionby eight iron raised entirely above edge is about upper nature
of
the
ore
using
this contrivance
sands
as
possible.
each
in
each
the
brackets
vat, about
level
with
being is to
as
the
tailings;
of the The
much
or
iron
of the
is thus
is held
ring
lowered
obvious
of
the staves,
the
staves,
sheet
a
vat, and
that
tank,
top
treated.
of sheet
ring
arranged
the
retain
of the
1 in. from
of the
the
ft. in
around
vat, consisting of
diameter so
10
launders.
This
level of
launders
the
from
and
admission
the
round.
way than
the
annular
before
is fixed
all the
diameter
off in annular
wide, fitted inside
extending
ft. in
14 with
water
is carried
2 in. less in diameter
the
fitted
are
tailings direct
the
receive
to
distributing-tanks,
slimes-arrester
iron, and
located
was
can
until
in
be the
according to intention
slimes
with
of
the
168
CYANIDE
THE
that and
attached
the
to
amalgamating New
and
described
slimes-arrester
The
and
staves,
having
which the
a
Mr.
and were
treatment
cyanide place
such
by
Fraser
takes
overflow
The
for
of the
introduction
J. C.
pans,
Zealand
PROCESS.
Fell
is
Price's
exactly
the
same
as
grinding
continuous
extensively used in Australia the of mill tailings before
process. in the space
great length
between of
the
ring
outflow, is
very
and even
the and
quiet. has a capacity of 50 tons plant, which day, consists of per and five leaching-vats, each 4 ft. deep, fitted 18 ft. in diameter with centre two discharge doors, and vats, each collectingvided prowith latter The the ordinary revolving reaction distributors. and the 10 ft. deep, and situated 14 ft. in diameter above are so each be one can discharged by shovelling leaching-vats, that three into of side-doors one adjacent leaching-vats. through any there these is a strong gold tank, a weak Besides gold tank, a waste-water vacuum tank, and two series of zinc extractors, each and each have are a consisting of twelve iron boxes, which square capacity of one cubic foot of zinc-shavings. The boxes are movable, The is independent of the other. and each two gold tanks are 10 meter the and 6 ft. deep, and 12 two ft. in diameter ft. in diasumps The
and
the
depth.
same
supplies the following working details : the actual This details of treatment, and the description shows the from which of Lot treatment results obtained 59, gives a fair of the treatment. example turned June 26th, at noon, on strong solution (0*24 per cent.) 6 in. deep on sands the stand stood 4 to until same ; allowed and At 4 p.m. allowed hours. solution to run opened outlet-cock the the last of solution into gold-tanks ; at 4.30 p.m., as was ing passtook which in off, sample, assayed "nothing" cyanide and dollars Closed in gold. fresh charge of 9*30 outlet-cock, admitted Fell
Mr,
—
"
"
solution, and
strong
June
allowed
to
stand
27th, opened outlet-cock,
8 and
At
hours. 1
night), (mid-
12.30 took
sample, dollars in gold. before, which assayed 0*06 cyanide and 28*94 as turned weak solution 1 At a.m. (0*08 cyanide), allowing same on without to drain through interruption till 4 a.m. Sample at 4 dollars in gold. Shut off cyanide and 8*08 a.m. assayed 0*10 allowed until and solution to stand outlet-cock 1.30 p.m. Opened admitted
and
outlet-cock to
12.30
(midnight),June
run
cyanide
allowed allowed
to
and
stand
fresh
solution
5
a.m.
(0*06cyanide) and solution
admitting at Sample taken dollar in gold. Closed a.m. Opened outlet-cock to run through until
28th.
0*62 until
solution fresh
through,
same
0'07
fresh
at
allowed
required till p.m. assayed
as
10
outlet-cock at
11
a.m.
5
a.m.
and and
Sample
APPLICATION
taken
OF
6
at
a.m.
sample
taken
At
a.m.
11
12.30
this to
of the
assay
and
cyanide 0*06
0*42
till
water-wash
dollar
and 2
and
0*21
p.m.
dollar
0*21
cyanide
tailingsbefore
0*21
occupied, 2 days
actual
is
recovery
difference, the
satisfactory, and
treatment
dollars
2*07
Time
If the
and
cyanide
0*6
ran
in
ran
treatment
84-1.
cyanide
in
equal
the
to
obtained
results
with
gold.
wash
drained
was
dollars, and
13*02
of
Percentage
recovery,
"
obtained
extraction be
must
by
considered doubtless
could
leaching
prolonged
gold; and dollar in gold. in
at Sample taken in gold; and sample dollar in gold. At
gave
2 '5 hours.
169
COUNTRIES.
declared finished ; the was process the tailingswere discharged.
; and
"Assay after
p.m.
the
point
waste
a.m.
006
ran
2
at
11
at
turned
p.m.
taken
0*06
ran
DIFFERENT
IN
PROCESS
THE
the
very be
increased.
Laurence
PROCESS
CYANIDE
THE
states*
Pitblado
that
IN
in the
INDIA.
Kolar
field there
are
at
cyanide works in operation. The ores of the field are simple, consisting mainly of pure quartz, with only a small very treated of iron pyrites. The is tailings from material percentage mills. first worked in the Mysore plant averaged the stamp Those 4*5 dwt. gold, and 65 an yielded average tion consumpper cent., with with 40-mesh month's In 1897 of 1 lb. cyanide test ton. a per the batteries in the screens following result : 90*65 per gave of the and on plates ; 74 per cent, in batteries cent, amalgamated value in the tailings recovered by cyanide lixiviation, making a six
present
—
total extraction The
of
cost
cyaniding
is
Company
£2,
but
alongside is
the
believed
Champion
of 97
that
Reefs
of the
cent,
5d. new
ton, per 4000-ton
mill,
cost
as
will
where
exclusive
delivered
to
mill.
the
plant of the Mysore preciatio deof royalty and
is being erected plant which tailingsthat is to be worked, it At the 2s. not greatly exceed
of accumulated the
ore
present small
the
at
10s.
in the
heap
per
20-mesh
are
screens
used
in
the
56 cent, tailings is about per with a consumption of 1 lb. of cyanide per ton. In refining the precipitate in this district it is first passed drained, dried, roasted with or without through a 30-mesh screen, small of fused nitre, and a directly in plumbago percentage before At the Mysore works the precipitateis retorted crucibles. month. The 100 lbs. of mercury roasting, yielding about per of mercury in the zinc boxes generally leads to the production presence of much-floured In fluxing and and brittle zinc. smelting
batteries, the
*
Journal
extraction
from
of the Societyof
the
Chemical
Industry,
Feb.
28, 1898.
170
directly, gold, 18
3
good
shots
many above
4*6 and
at
dried
a
acid washed
product
cent,
soda,
metal
and
silver, zinc,
heat.
(1
a
2*71 0*12
10
per
bullion cent,
per
per
fluxed
cent,
at
per
cold
sand, 81
assaying lead,
the
6*78
*3
per
cent,
per cent,
gold,
2*10
zinc, the
free
gold, copper,
roasted phuric suland
dried
The
slag
retorted
dilute
with
cent,
per a
cent,
and
nitre
copper.
35
giving
The
boiled
are
a
than
freer
unsatisfactory,
of
cent,
about
per
works.
Mysore
they
'5
copper,
being
per
dissolves
cent,
nickel.
the 10
with
cent,
results
with
which
assayed
38*21
These
When
2),
:
is
and
lead,
mixed
are
red
a
slag
a
49
copper,
contained
slag
nitre
cent,
per
cent,
per
The with
bullion
56*4
19*6
nickel.
roasting
adopted
was
slimes
bright
and
nickel.
lead,
cent,
per
assayed
bullion
cent,
per
In
4*29
cent,
practice
the
metal.
silver,
per
following
0*1
produced,
cent,
0*22
and
of
was
per
2*4
and
zinc,
cent,
slimes
silver,
cent,
per
per
the
retorted
the
PROCESS.
CYANIDE
THE
borax,
15
from
shots
6
'9
0*4
per per
per of cent,
cent,
CHAPTER
XII.
PROCESS.
SIEMENS-HALSKE
THE
of extremely the use of this process are distinguishing features dilute of cyanide and the electrical precipitationof the gold. solutions the the of the cyanide process, introduction Since precipitation weak has been zinc of the gold by metallic a regarded as always in the endeavour time much point ; and metallurgists have devoted The
discover
to
efficient
an
substitute
for
it.
of many precipitation naturally engaged the attention investigators. In 1893, the author, assisted by Mr. F. B. Allen, electrical of number M.A., B.Sc., conducted a experiments with method of the precipitation to be precipitation to determine different of Mines adopted at the School cyanide plant. Many modifications With the tried. precipitation from were some, solutions of ordinary working strength was satisfactory; but, very with dilute solutions, such all, the precipitation of the gold from those always very as corresponding to weak cyanide washes, was imperfect and accompanied by decomposition of the water. this Siemens-Halske In the by difficultyis overcome process in the the of solutions slow artificial circulation cyanide causing a
Electrical
extractor.
The
gold the
the
are
only
marked
has
difference
Goldfields, has
little
the
process A. Mr.
and
and
its
I
been am
Von
Society of Mining Journal.
to
written
indebted
Zealand
New about
Gernefc, read South
gold has been cyanide plants Up extending.
is
to
the
it.
the
papers
before
Africa, and
For
the
the
at to
Witwaters-
the
the of
following Mr.
Chemical
published
in
the
Charles
and South
it
present
Australia, and
or
with
introduced
of
of
use
introduced
been
very
number
in
the
extractor-house.
being in the precipitation a
leaching of the preceding chapters,
with
connected described
those
as
at
success
not
operations
same
electrical
The
rand
and
plant
so
far
details
of
Butters
gical MetallurAfrican
172
CYANIDE
THE
Discovery electrical has
the
Dr.
found
Siemens his
at
works
in
the
cyanide solution,
the
bath.
This,
soluble
was
the
try
in
extracted
Asia the
that
Berlin
lost
without
Von
Mr.
—
from far
as
by
ores
back
gold anodes weight when
he
built
small
the
cyanide
1888.
as
used
electric current any with the well-known
connection
said
Gernet
in
In
plating electro-
standing idle in passing through fact that gold
in aqueous solutions of cyanide, first induced solvent of that for the extraction of gold from
use
the
In
Process.
precipitation of gold in use in Europe and
been
1887,
of
PROCESS,
him
to
ores.
make
plant experiments The on produced Siebenburgen. gold was cipitated preboth and zinc It found, electrolysis by was filings. results from however, that the zinc method good paratively comonly gave the electrical strong solutions, while precipitationwas both effected with dilute and and its efficiency strong solutions, affected the of caustic soda. not was by presence Dr. Siemens therefore decided to use electrolysisonly, and early in 1888 he commenced operations on a large scale. Engineers different sent to to were countries, two going to Hungary, one and America, one (Mr. Von Gernet) to Siberia. The generally successful, and in May 1894, a operations were of tailings per tons plant, capable of treating 3000 month, was erected at the Worcester mine, near Johannesburg. During 1895 the process was adopted by some panies, eight or ten large mining comConsolidated, Croesus including the Metropolitan, May same
year
in
concentrates
G.M.
Co., No.
4 Central
of Gold.
tion
rival
Electric
of the The
and
Works,
already it is a formidable precipitationprocess. Action
a
to
electric
Robinson the
of
Current
Slime
Works
Mc Arthur-Forrest
on
the
Cyanide
; and
zinc-
Solu^
decomposes the auro-potassic solution, depositing the gold on negative pole and liberating the the In metalloid fixed at time a positive pole. a given electric will deposit a certain current of which metal, quantity will different for metals direct in quantity proportion to vary their electro-chemical equivalents. This law holds good only for —
current
the
solutions
strong
in
metal
;
but
with
very
dilute
solutions, as
in
does current sufficient not of cyanide process, the and at electrodes, compound present consequently takes also of this for water to make decomposition place ; reason, the diffusion of the precipitationas efficient as possible,constant use
in the
the
metallic
solution
The and
is
the
find
required.
artificial
circulation obtained
of
the
solution
is most
economically but steady flow highest importance
slow
conveniently by allowing a It is of the boxes. the through precipitation to give a very large surface to the electrodes, since
a
more
efficient
174
CYANIDE
THE
PROCESS.
advantages gained by using such
The
1. The
gold
is
deposited hard
current
are
:
—
lead- foil.
the
on
weak
a
preserved for a long time, as their In current is in proportion to their waste strength. 1080 lbs. of iron tons a plant treating 3000 per month, are destroyed in that period. Watts is required. 746 Little equal 1-horse power A 3000- ton plant requires 2400 Watts, equal, power. and actually requiring theoretically,to 3|-horse power,
The
2.
3.
anodes
iron
are
5-horse
about
power.
claimed
advantages
Electric
of
Advantages
The
this
for
Precipitation.— are
process
The
follows
as
:
cipal prin-
—
the
precipitation operates independently of the caustic of cyanide or tion. soda amount present in the soludilute of tailings, Therefore, in the treatment very be used, the solutions can only limit being a sufficient quantity of cyanide to dissolve the gold satisfactorily. of cyanide will A solution dissolve cent, containing 0*03 per gold as effectivelyas a solution containing 0*3 per cent., provided is allowed In the for treatment. the first case, a longer time less than ing in the second, resultdecomposition of cyanide is much in a corresponding economy. That
1.
acid
2. However
the it does
as
solution
the
takes
precipitation
when
the
when
be
may
solution
the
entering
place equally
is neutral
tractor, ex-
well
as
alkaline.
or
of lime, alumina, complications arise from the formation sometimes in the trouble or hydrate of iron, which cause zinc process of precipitation. 4. With of ores or tailings containing copper, the extraction the will the be but the of gold decomposition same, cyanide less than when using stronger solutions. No
3.
5. The
The
successful
Actual
place
at
of
this works
cyanide Johannesburg,
the
near
of
Working
demonstration
of slimes.
treatment
the on
process of the under
Process. a
Worcester the
—
The
first
commercial Gold
supervision
cal practi-
scale
took
Mining
pany, Com-
of
Mr.
A.
Von
Gernet. The stone
of five leaching vats plant consists beneath. a single tunnel piers, with with
in
diameter,
of
tailings. Between
two
tanks,
intermediate
the 16
10
vats
ft. in
ft. staves, and
and
the
electric
diameter,
reservoirs, which
with enable
has
a
placed Each
on
a
is
vat
capacity there
row
of
100
20
of ft. tons
placed 6 ft. staves, forming two the flow through the pre-
extractors
are
SIEMENS-HALSKE
THE
cipitation boxes of
matter
A
method
into
to
secure
be
kept
and
constant
tank
an
flow
even
is
steady, a
and
all the pump overflow into
to
tank, provided with
raised
small
a
intermediate
the
to
great importance.
better
solution
extractors
or
175
PROCESS.
an
the
delivery pipe precipitation full to always kept overflowing, so that it delivers under a constant hydraulic head. 20 ft. in Beyond the precipitation boxes there are two sumps, which diameter 6 ft. deep, from and the are cyanide solutions returned to the leaching vats. Two 8 ft. deep, receive and collectingvats, 20 ft. in diameter the tailingsfrom the 25-stamp battery. boxes.
The
The
small
tank
Electric
a
is
Precipitation
boxes, constructed and
4 ft.
iron
wires
to
of
Boxes. each
wood,
There
—
18
ft.
are
four
cipitation pre-
long., 7 ft. wide,
box contains 89 deep. Each iron-plate anodes, 7 ft. by 3 ft. by £ in., cased the small in canvas retain to quantity of blue and Prussian 88 stretched of lead-foil cathodes produced ; on
strips,3
fixed
ft.
2
by
there
lead-sheet,
a
on
wooden
ft.,so
Each
frame.
that, counting
the
frame
double
three
contains surface
of
each
feet of cathode 3000 altogether about square foot. surface, the current density being 0*05 ampere per square Copper wires are fixed along the top of the sides of the boxes, and the current the dynamo from to the electrodes. convey The boxes of 3 in. material made ing are throughout, with stiffenthe sides and bottom. The divisions are of wood, pieces across formed of the iron inch or are by raising some plates about an the above level of the solution, while others rest on right down the bottom, the joints being made of wooden water-tight by means fillets caulked with series of hemp packing. By this means a is similar in a zinc to those obtained, compartments precipitation the difference that the solution box, being alternately up passes and down successive The of flow is rate through compartments. about
foot
one
The
are
minute.
per
Clean-up. month
—
The
boxes
are
kept locked, being
opened
the
replaced by
fresh
follows: "clean-up," which is conducted as and lead-foil the removed and out is singly, lead-foil,the whole operation taking but a few
minutes
each
frame.
once
The
a
for
—
frames
are
for
taken
The
lead,
which
contains
from
2 to
12
and into bars gold, is then smelted cupelled. The gold is deposited on the lead sheets as a thin bright yellow adheres The film, which firmly to the lead. consumption of lead the Worcester 750 Works is at lbs. per month, equal to 1 £d. per of tailings. ton The working expenses for treating3000 tons per month were as per
of
cent,
follows
:
—
176
THE
The
cost
The
tailings assayed
residues,
of treatment
after
weak
the
strong
of 2s. 8d.
amounted use
per to
of the
amounted
to
of 2*240
lbs. would
dwts.
8 dwts.
to
1 dwt.
to
74
per
1 dwt.
be
of
dwts.
2
3s. 4*32d.
gold, and per
cent.
precipitation boxes, still showing by assay 4 dwts. 8 of
the
The
ton.
the
ton grs. per carried from
solutions
solution.
4 dwts.
grs., age, aver-
the
dwts., and
5
to
the
On
tained con-
gold per ton of solution. pany 1895, the Metropolitan ComMay for 4845 of at of tons 26,900 ozs. a cost gold, tailings the working expenses At the May Consolidated ton. about 2s. 4d. per ton, excluding the royalty for the to
grs.
1894
over
of
of
to
which
amounts
80
cent,
process,
Details and
solution 10
PROCESS.
about
was
leaving
November treated
from
after
solution
10
from
From
6
strong
solutions,
the
weak
ton
extraction
gold, the and
per from
treatment,
actual
average The
CYANIDE
the
per
Treatment.
washing, together with following tabulated
in the
the
3
to
per
The
cent.
of the
extraction
value.
original assay time occupied in leaching quantity of the solutions, are given The
—
statement
: —
HOURS.
Alkaline
wash,
10
3
tons,
Strong cyanide solution, 70 tons,
0*05
to
0*08
per
cent.
65 applied in 14 separate portions of 5 tons each, Weak cent. cyanide solution, 21 tons, 0*01 KCy, per 18 applied in 3 portions of 7 tons each, charging, disWater washes, total 1 1 tons, pumping dry and
KCy,
22 ........
Total, The number
working of
of
valuable
lead, litharge,and
this
process
commercial
paint.
108
gives
rise
to
the
production
bye-products, including
of
copper,
a
CHAPTER
OTHER
The
Diehl
Teed
process. 1. 2.
XIII.
CYANIDE
Process.
This
—
It embraces
Crushing Treating
and
is
adaptation following essential
the
in
Sulman-
stages *:
—
ore.
agitators
cyanide Filter-pressingthe sludge. 4. Precipitating the gold from the character of to According and concentration amalgamation can in
the
of
an
the
sliming slimes
the
PROCESSES.
with
solution
a
with
combination
of
sium potas-
bromide.
cyanogen
3.
The treated At
in
30-mesh and
"
a
raw
dry-crushed
and
added
be
to
its the
is,
process
and
associates,
process.
that
is
ore
10
elevated,
the
is
ore
15
introduced,
per
provided
mixed
sands
The
to
first
ball-mills
Krupp
slimes.
from
was
process
5
crushed
which
on
the
No.
two
sands
into
copper-plates
in The
screens.
classified
the
of zinc.
means
condition.
mill, where
Star
by gold
this
of
advantage "
Haunan is
ore
direct
most
solution
with
with
water,
conducted
are
of
cent
the
to
gold
the
is
by gravitation to the plates the pulp travels in a large it is ground into slimes fine-millingdepartment, where is an 18 ft. long steel cylinder, 4 Krupp tube or flint mill, which ft. in diameter, charged with 4 tons of flint balls. The is fed sand saved.
From
into
end
one
whole
the
and
product
issues
will
pass
at
the
other
through
a
of
sieve
such with
a
fineness
200
mesh
that
per
the
lineal
inch.
grinding mill the pulp is led to settling vats, from which the surplus water The is returned to the mixing machine. thickened led where into is treated with it pulp is now agitators, and bromide solution of of of a cyanide potassium potassium. When the agitator has its full charge, a strong solution received of potassium cyanide is added. slimes For containing 1 to 3 oz. of gold per ton, we much have it sufficient to add found so cyanide that there will be 4*4 lbs. KCy of dry material. After the per ton From
the
*
Knutsen,
Trans.
Inst.
Mm.
and
London,
Met.
1902.
,
12
178
has
sludge bromide
hours the
case
contain
BrCy, to ensure hand, if the sludge contains quantity of KCy and BrCy can About
before
2 hours
1 lb. to to
the
is added
lime filter-press, 4 lbs. per 4 lbs. is used.
ton
A
good gold
a
less
oz.
than
1
oz.
the
ton,
per
ready to discharge to the sludge in quantity varying from is
In
slimes.
cleaner
per ton, it may agitation,a further quan On the other extraction. 3
considerablyreduced.
be
the
dry
in,
than
more
agitator
to
of
quantity agitator is kept going solution charged into it. was
8 hours'
6 to
of
added
the
The
KCy
and
KCy
tity of
flow
solution
the
1£ hours,
to to
the
after
add,
to
1
material.
time
should
sludge
advisable
be
for
dry
of
the
from
PROCESS.
is allowed
cyanogen lb. per ton
1*1
24
for
agitated
been
of
being In
CYANIDE
THE
the
most
I
cases,
in the
obtained
precipitateis thereby
3
think,
boxes.
zinc
agitation,the
After which
dissolved
the
of slime
cakes The
gold ordinary
the cent, this
the
is
which
doubtless
so
month
of
Hannan's
The is
scarce.
tends
July
dump. precipitated with
1901,
Brown
the
an
available
retard
the
zinc
2210
over
per
small
in
goldfield,where
a
is salt
brackish,
or
concentration. of the
summary of
tons
Kalgoorlie, by
at
93
is very
on
in
turnings
of
extraction
water
close
following
when
Hill,
that
consumption important factor
to
gives
out.
of water
an
All
Feldtmann
Mr.
is
After
the
It is claimed
which
water
on
in filter-presses, the dry washing,
Dehne's
in
pressed
washed
solutions
way.
process,
is
out
obtained.
be
can
thrown
are
in
pulp gold is
were
ore
this
for
the
treated
at
costs
process
:
—
Summary.
Milling,
.
Concentration, Treatment
of
.
concentrates,
Extraction, 0-88
24
The of barium
Schilz
inasmuch
under
after it
the
is based
process
that
the
oxide
normal
the
performs sulphate of
and
oxide
of
dispenses
further iron
iron, with
one-half
with
parts
treatment,
it
the
on
addition
ordinary cyanide solution,
conditions
claimed
decomposes forming sulphate of barium removes sulphocyanides, and as
the
to
certain
It is further is left
This
—
peroxide, Ba02,
it is claimed oxygeu. which
Process.
in
of
the
use
its
barium,
functions
—
solution,
insoluble
both
the
of
which
of lime
; it
and
OTHER
the
answers
addition. time
CYANIDE
minor
of the same, with other purpose other On the hand, the process
effect
satisfactoryextraction than in increase necessitatinga considerable to
thus
well
a
Schilz
Herr
sprinkled with a good mixture
that
solutiou
than
for
is the
be
at
least
is
washed
should
is
extraction, with
remain
three
and
six
the
vat
is
A
rather
allowed
stand
to
the
longer
of
case
being filled,so stronger cyanide
whole The
days.
in the
be
must
the
time
it should
concentrates
running off the gold solution the residue cyanide solutions, the first of which Then, again, a strong solution should
After weak
four
peroxide
the
and
in,
advantages in longer requires much in ordinary cyaniding, vat capacity. the
success
obtained.
run
least
at
ensure
be
may
week.
a
to
tailings whilst
the
usual
undisturbed better
that
states
179
PROCESSES.
hours.
be
applied, followed by weak solutions. quantity of peroxide depends less on the percentage of gold than on the length of time during which the solution remains the in contact with charge; and, further, the more pyrites present The the should the of vat peroxide. consumption greater filled to the brim be the with the tailings, swells up not mass as The
the
by
evolution
liberated in
of gas,
oxygen with
contact
sometimes
should the
much
as
the
charge,
ton
Delivered
treated.
ore
is "£50
peroxide A working according to
per
the
of
report
iu extraction per cent, rise from 76 89 to per
The 1.
BaO
Ba02 and
also
gave
inventor
makes
at
a
manager, small
the
3.
contact
the
the
dissolution
the
cold.
basis,
in
exerts
solutions,
a
thus
peroxide
J
from
lb. to
the
renders
of which
has
lb. per
1
of barium
cost
and
Suburban
showed additional
cost
about
that
—
the
of
treatment
mine, of
gain
a
for his
is, a
pyrites
process
moistened
with
:
—
tailings into
cyanide of potassium with oxygen of gold. This decomposition which the
is
reduced
required for pyrites, and
is
the
thus
enclosed
gold. decomposing supplies BaO, which, being the purifying and clearing influence upon their increasing solving power.
Ba02
4. use
liberating the
Ba02
of
the
treatment.
following claims
Ba02 supplies the oxygen decomposition and dissolution of in
quantity
of
satisfactoryresults.
2.
assists
the
possible
as
action
City
The
cent.
decomposes in 0, and supplies
required for performed in
long
as
Rand,
the
at
process
13
concentrates
Thus
ton.
trial of the the
the
on
foot.
a
solvent
greatest
cyanide being after a few days. The under required varies with the material In actual practice the quantity varies of
as
undisturbed
remain
superfluous the in its train
so
many
use
of
lime, the
now
injurious secondary
a
strong
cyanide existing effects.
180
THE
CYANIDE
Park-Whitaker
The intended
for
which
the
successfully the
of
Process.—
cupriferous
of
treated
account
on
processes,
Cyanide
treatment
be
cannot
PROCESS.
and
ores
the
by
solubility
This
of
concentrates
cyanide
ordinary
cyanide
in
ores
copper
is
process
solutions. this
In
the
process
after
which
with
water.
soluble
the An
with
the
During
which
of
results,
and
gold
cyanide.
of
present
dissolved
by
converted
are
The
cyanide.
solutions
the
passing
leaching
the
solved disiron
through
scrap-iron.
or
Experiments parcel
by
roasting,
by
and
sulphides
readily
is recovered
copper
turnings
is
removed
applied,
solution
silver
chloridizing
a
are
is then
dilute the
roasting
chloride,
into
wash
a
to
chlorides
copper
alkaline
extracted
silver
subjected
is
ore
Monowai
the
from
ore
and
scale
working
a
on
preparations
are
were
made
mine,
N.Z.,
with
made
being
now
the
by
author
on
a
most
successful
more
extensive
for
trials.
The
Pneumatic
dissolution
of
air, which
the
cause
the
partly by
continuous
aeration
air
is conducted
perforated pipe placed This
provisional
letters
Tests
made
rapid
was
separating
argentiferous
an
amalgamation
amalgam, promote
many
gold
and
pulp, of
passage
the
complicated
a
the
of
slimes
found
was
gold
difficulty For to
give
of so
gave
abandoned.
were
1895.
Kuaotunu
at
the
from
of
which
in
mechanical
This
Central
a
pulp
of
the
the factory satis-
operated essentially method
copper
cyanide
doubtful
is
Washoe
alkali,
containing
been It
America.
caustic
reactions
has
process
closely following
to
Zealand author
coil
aeration. —
of
a
for
dissolution
the
percolation
in
ores
addition
mercury
but
artificial
process,
The
and
the
through
New the
The
attempts
Process.
Young
treatment.
compressed
process,
in and
solutions
ordinary
without
on
Park-Horn
slimes.
further
sands,
the
George fine
charge
filter-cloth.
complete,
that
results
Gilmour-
of
the
process
of
the
by
the
Horn
gold-containing
the
the
obtained
were
Mr.
almost
and
of
treatment
patent
by
trouble
much
with
excessively
goldfield on
caused
to
of
top
on
is identical
process
were
gentle agitation
solution
the
this
partly by jets
and
of
In
charge.
compressed
The
Process.—
is accelerated
gold a
the
through
air
Cyanide
and
solution
utility.
of zinc must
182
THE
The from
anodes two
There
are
bars
are
cathodes
PROCESS.
1 in. thick
of iron
curved
girders and twelve
CYANIDE
so
to
as
in the
by 3 in. wide, suspended parallel to the cathodes.
be
vat.
The
twelve is revolutions agitator running about per minute found sufficient to keep the pulp from settling. The salt in the renders local water the conductivity of the pulp excellent, so that low of very current a potential is quite sufficient to effect the current required for gold. The precipitation of the dissolved each of 18 tons is about 250 of a potential of 2-5 vat amperes about to of six-sevenths electrical volts, equal an horse-power, the of which is merely nominal. cost per ton The is first pulverized until all the gold is liberated its from ore If necessary the ore results it is merely necessary fine state able, or in such a
matrix.
is roasted.
that
In
order
the
to
should
obtain
good
be
gold amalgamof dissolution as permit by cyanide solutions. requires a particular ore Necessarily each certain specificpreliminary preparation, determinable by experiment, to
obtain
the
best
will
results.
The
pulp, containing approximately the vat solution, is discharged into which the
is called
the
electric current
vat."
electro
"
from
the
maintained
The
equal weights of ore and previously described, and agitator is set in motion,
dynamo by means
is
pumped
back
of
started,
and
the
flow
of
the
air-jet,as already The of potassium cyanide to the described. solution is made up With of a high-grade ore strength of 0*075 per cent. average is continued for about 2 oz. or over the above-described operation while with slimes, carrying but 3 dwt. hours, low-grade eighteen 4 dwt., it be be six hours. After or a complete in about may time has elapsed the discharge-valve at the bottom of the proper dam is opened and the pulp is allowed to flow vat to the residues ; the operation indefinitely the vat is refilled as before, and repeated. If water the is scarce, liquor, after the pulp has supernatant quicksilver
settled
pulp
is
in the
dam,
be
may
succeeding charges. clean-up is effected by time, and replacing it with is
this
keep The or
the
mill
to
make
for
The the
into
very
process it active Kiecken
decantation
fine, and sodium
contains is
added
withdrawing
plate at The a one. amalgam spare duced proabout of fine gold. In 27 per cent, the to automatically to mercury one
copper
and
bright. dispenses process
for
the
removal
with
percolation, filter-pressing, dissolved the ore, gold from and clean-up, the zinc-precipitation of the
with entirely away its mechanical of the preparation, complete treatment ore, after of vat, in the minimum operation in one being effected in one the recovered as time, gold being amalgam, requiring only retort-
and
does
OTHER
and
ing
with
The
much
Keith
cyanide
is
process
he
practice,
of
claimed,
operates
the
of
cent,
per
This
mercury.
very
of
the
In when
obtained
of
than
of
mercury.
and
cyanide
mixture
faster
much
solution
the
are
potassium
covery re-
improvement
to
results
for
the
second,
cyanide
best
trician. elec-
process
Keith's
adding of
finds
the
and
;
Dr. in
amount
0*05
be
electro-
American
First, ore
solution.
Keith
an
parts.
consists
he
will
process
—The
Keith,
crushed
the
that
cyanide
Dr.
two
the
certain
a
contains
cent,
per
of of
process
states
solvent
the
from
gold
cyanide
potassium
Process.
of
out
this
of
metallurgists.
by
consists
dissolving
the
applications
invention
gold
the
of
the
process
the
dissolving
future
interest
Electro-Cyanide
The
in
The
melting.
watched
183
PROCESSES.
CYANIDE
0*025 it
cyanides,
simple
is
potassium
cyanide. The
electrolytic
scraped usual
with
a
gold
The
be
is
solution
more
and
the
placed of
an
than
in
The
a
salt, electro-motive
volt.
to
so
off
into
dip
and
force
of
the
an
is
deposited
in
mercury the
cyanide
surrounded does
cyanide
the
that
the
is
together
deposited
compartment so
solution
amalgam distilling
by not
the
are
allowed
separate
a
alkaline The
half
is
from
gold mercury
recovered
anode
decomposed.
become not
the
way. but
solution,
gold
the
copper-plates.
and
off
of
recovery
The
one.
amalgamated
upon
the
the
for
process
current
not
need
CHAPTER
XIV.
ANTIDOTES
cyanides
All in
practice
are
acid
prussic
Acids
evolved
with
death
it
air,
them
from
inhaled
faintness,
in
and
causes
diluted
When
frontal
depressing
a
tilated. ven-
which
gas,
state.
pure
a
dizziness,
properly
are
acid
prussic
the
from
danger
no
buildings
the
if
or
used
solutions
aqueous
little
is
liberating
when
causes
the
but
;
there
that
cyanides,
on
instant
poisons
dilute
so
react
almost
deadly
are
POISONING.
CYANIDE
FOR
headache. Even
dilute
very
and,
internally, in the
hands
the
of
they
gloves,
in of
be
must
arms
Kaffir
whatever
workmen the
from
into
the
contact
where
with
the
be
venience incon-
no
with
skin
tion, solu-
provided
suffer
to
their
produce,
cases
should
said of
In
contact
elbows, are
skin,
boils.
red
painful
over
the
with
contact
taken
when
poisonous
are
brought
reaching
workmen.
cyanide
come
eruption
an
and
rubber for
when
persons,
some
solutions
cyanide
solutions.
Considering accidents fatal
have
principal
Up
poisoning
namely
:
From
hydrocyanic
From
poisonous
i ia.) b.)
the
cyanide, to
number
the
present
be
apprehended
fatal
of
only
time
a
few
recorded.
plant,
sources,
of
use
small.
been
cyanide
a
extensive
remarkably
is cases
In
the
may
from
two
—
acid
liberated
in
liberated
gases
vat-house. acid
during
of
treatment
slimes.
In
South
covered the
Africa,
by
action
roofs, of
risk
can
be
from
danger acids
mineral Even
unknown. reduced
and
Australia,
to
or
where a
countries
prussic
minimum
vats
by
are
the
acid, in
enclosed free
vats
are
liberated
vapours, carbonic
atmospherio the
the
where
acid
circulation
a
is
shed, of
not
by tically practhe fresh
air.
The
author
has
observed
that
the
presence
of
HCy
vapours
is
ANTIDOTES
CYANIDE
FOR
185
POISONING.
agitation than in percolation plants, the obvious reason being that agitation is generally adopted for the and while the strength of of pyritic ores treatment concentrates, the solutions used is nearly always high. In cases of hydrofumes of cyanide poisoning by inhaling the cyanic recommends chemist the of acid, a German gen hydrouse with which forms the harmless HCy pound comperoxide, H202, reaction the the oxamide, following being represented by equation :
always
in
noticeable
more
—
2HCN
This
is said
known
the
a
effect
same
foreman
HGy
reliable
most
poisoning
immediate,
was
gS|-
=
and
satisfactory remedy
present time. of
case
gas
The
the
at
In
the
be
to
H202
+
fell into
was a
the
of
one
observed
cyanide
at vat
the
at
Crown
workmen N.Z.
the
without
Deep, the falling as Crown
effect
of
dead.
if
where
mines,
previous warning and
a
died
immediately.
Danger
during
Acid
of
Treatment of
small
Slimes.—
slimes
The
insoluble
a cyanide salts, generally proportion acid when the which acid is poured sulphuric yield hydrocyanic To them. be on guard against this danger, repirators should used have the dissolving tubs, who to stoop over by the workmen In cases subcutaneous of poisoning, said injectionsof H202 are mine Mr. T. L the Crown enable the Carter to of Deep by patient
contain
to
soon
come
to.
of which less soluble are more or containing arsenic, most in cyanide, there is a danger of arsenic being precipitated with the the the acid treatment of such slimes, zinc boxes. gold in During would be the deadly poison arseniuretted liberated hydrogen by the action the zinc. of the sulphuric acid on In
The
while
ores
of the North in the observed case symptoms foreman the mill, where superintendent,and first nausea, others affected, were were many
followed
Pole
pany's Com-
both
died,
then
extreme
of the langour, pains legs, by skin in patches assuming the hue whites of tan ; the of the eyes became yellow as in jaundice ; finally,the passing of blood instead of urine that the fluid coagulated jn a few hours, extent to such an the patients apparently dying from internal mortification. arsenic from the The lungs through the being inhaled, passes whole the tissues of the body, presystem, and rapidly attacks cluding relief of antidotes. means by any the acid Where is used, the zinc for treatment precipitation with
purposes
should
in
be
free
the
from
arsenic
; and
discoloration
in all
cases
the
dissolu-
186
CYANIDE
THE
tion
of the
zinc
should
PROCESS.
conducted
be
in
or special chamber board cupa chimney having a good draught. In cases of internal be induced at poisoning, vomiting should once by emetics or physical means. of iron, obtained Freshly precipitated carbonate by mixing equal of and sodium ferrous carbonate quantities sulphate, is recommended
connected
for internal It
a
a
with
use.
garian lately reported in the press that Johann Antal, a Huntoxicologist,had found that a solution of cobalt nitrate was for prussic acid poisoning. Eecent perfect antidote tions, investigawas
have
however, animals
on
and
for
when this
human
salts
exert
toxic
a
injected subcutaneously, finallyleading nitrate
reason
cobalt
of
be
cannot
action
death
to
recommended
;
for
subjects. Sores.
Cyanide
A
—
the
"clean-up"
sores
in those
parts
cyanide
solutions.
with
afflicted
some
connected
on
in
These
zinc
of
their
hands
Why
workmen
are
affected which
arms
some
clear,
very
in contact
come
should
men
engaged in with painful
be
but
and
exempt
it is
probably
causes.
subject, Mr.
Watt
A.
the
supplies
following
—
arise
may
hands
the
dipping
which
or
is not
way
painfulaffections
first,from
the
extractors
constitutional this
of
percentage
the
this
notes*:
instructive
articles
of
with
Writing "
cobalt
that
shown
or
from
into
arms
them
two
principal causes
cyanide
baths
to
:
recover
dropped a common practice very and the accidental second, from condemned; of the fingers or other contact recent parts of the hand, on which a scratch has been with In the cut inflicted, or cyanide solutions. the constitutional former of which mischief independent case, may the skin from the of the arise absorption by cyanide salts,the caustic liquid acts very freely upon the delicate tissue of the skin, the the parts under but We more especiallyupon finger nails. have known instances in which has formed under purulent matter both this the nails of from hands necessitatingthe use of the cause, when lancet and in cyanide solutions come poulticing. Again, wounds with of contact recent even slight cuts or abrasions very and skin troublesome the is sure to exceedingly painful sore a and
much
to
into
have
—
be
—
—
result, unless it is it
a
a
in rag
or
strip of thin
in
dip
momentary
be
part
good plan,
very
moments
clean
the
after a
of
*
rinsing
weak and
acid
the
in
part
in cold
pickle, then
drop a gutta-percha."
olive oil and
Watt,
of
Electro-Deposition,
p.
611.
; indeed
water
warm
wiping the
towel, apply sheet
soaked
once
after
water,
warm
at
water,
soak
it for
part dry cover
to
up
give
a
few
with
with
a a
ANTIDOTES
Provision
CYANIDE
FOR
Remedies.
of
187
POISONING.
In
order
minimize
to
the
danger
—
attending
cyanide in
provided a
glass
part The
cyanide
every
the
works,
cabinet
marked
Poisoning
printed
to
should
all
have
instructions
the
be
cabinet
with
accessible
easily
Antidotes the
near
for and
top,
remedies
the
apply
to
closed
a
and
words
letters
how
in
should
workmen.
the
clear
in
kept
conspicuous
some
known
antidotes
necessary and
plant,
in
placed
front,
of
the
poisoning,
Cyanide written inside
pasted
or
the
cabinet. The
1.
cabinet
A
solution
of
drawn
to
2.
A
solution
should
sterilized
a
hydrogen fine
the
and
point
flask
glass
hydrogen
sealed
3.
hypodermic
4.
A
stomach
5.
A
small
6.
A
small
triangular
7.
A
small
pair
and
B,
of
medicine
file.
pinchers.
of
filled
with
glass.
glass.
:
with the
with flame.
—
3
a
per
cent,
should
flask
be
flame.
blow-pipe
funnel.
conical-shaped
of
neck
a
sealed made
syringe, tube
in
marked
peroxide,
A
filled
A, The
peroxide.
articles
following
marked
flask
glass
sterilized of
contain
a
30
per
cent,
INDEX.
of
Absorption Acid
cyanide
by washes
preliminary
ores,
slimes,
smelting
tailings,
vats,
of,
6.
for,
69.
Antimony,
influence
Appliances
used
cyanide
of
Assay
108.
tables,
76.
slimes,
of
treatment
110,
111,
acid
Africa,
slimes
of
treatment
in,
crushing
wet
in,
leaching,
Agitation
81,
at, 167.
10.
121.
97.
91,
97,
96,
138, Base
peroxide, metals,
of, 178.
use
estimation
of,
tions, solu-
in
177.
151, Air,
of,
96.
94,
by,
86,
practice
Mine,
Barium
82,
Company,
125.
extraction
Agitators,
Westralia
65.
influence
Banket, actual
48.
31.
46.
at,
Athabasca
Azurite,
113.
111,
leaching,
solutions,
and
Associated air-lift
113.
of, 13.
for
43.
compressed,
of,
use
180.
Bonanza compressors,
ner
lifts, 65,
66.
slimes,
practice
in,
practice
Columbia,
167.
63.
Ealgoorlie,
at
Bromo-cyanogen,
of,
use
178.
64.
wheels,
Bucket-
63.
55.
pumps,
Alkali,
115.
at,
process
British for
Tave-
Johannesburg,
Mine,
83.
65,
doors,
discharging
Butters'
protective,
57.
166.
73,
distributes, of, in
estimation
165.
155,
solutions,
44.
Alkaline
cyanides,
influence
sulphides, wash,
of,
Calculating
14.
181.
Pan-amalgamation. Zn
of
cost
extraction,
percentage
20.
practice
California, 180,
processes,
also
America,
34.
75.
Amalgamation See
for,
tests
Camp
Bird
in,
161.
acid
Mines,
treatment
at,
113.
precipitation
in,
practice
15,
at,
102,
103,
155.
120.
dry crushing sulphuric
in,
acid
in,
110,
Analytical
of
solutions, methods,
41,
Feldtman's, Green's,
Antimonite,
173, for
Cathodes,
43.
soda,
influence
poisoning, of,
11.
185.
in
Channels,
96.
56.
at,
of, 75.
of, 75. 152.
pumps,
Chalcopyrite,
181.
use
use
Centrifugal
33.
the,
173.
lime,
Caustic
36.
cyanide
of
tell-tales
35.
Virgoe's,
Antidotes
of, 7.
Company,
Extraction
practice
22. 33.
Crosse's,
Anodes,
Gold
Cassel 142.
113.
Analysis
influence
oxide,
Carbonic
1 25.
refining
influence
sulphide formation
ores,
of, 12. 93.
of, 83.
11,
INDEX.
190 methods, 84. Filter-presses, practice,N.Z., 87, vats,
electrical
151.
Tavener
gold, 80. Fluxes, for lead smelting, 117. in gold concentrates, Franklinite Free milling ores, 17. sulphur, influence of, 13. Freely percolating tailings,vats
93.
117.
melting slimes, 109, gold slimes, 109. of, 13.
influence
10, 75.
Kauri
Gold
Eeith
electro-chemical
Estates, ores,
Gold
Eomati
sulphide ores, 93. GilmourYoung process, 180. of, with sulphur, Gold, combination in
12, 144.
Works,
Eapai Vermont Earangahake,
Eiln-dried
Galena,
122.
180.
for,
for of
plant at,
new
Kalooorlie, air-lift at, 64. practice in, 87, 89, 144, 146,
66.
Fusion
in, 115.
process
Jumpers Deep,
"Float"
Furnace
73.
practicein,
63.
required, 81, 84.
Fineness
plant at, 67. precipitationat, 174. of
cost
Johannesburg,
ores
from,
128.
process, 183. behaviour of, 7, 12.
Mine,
from,
ores
15.
Eoppel patent tank doors, 58. Euaotunu, practice at, 12, 75, 180. 104,
92.
14.
results
precipitationof, by zinc,
100.
smelting of, 109. Cyanide Works,
plant
Gate
Golden
at, 163. and
Grain
gram
table, 46.
Proprietary, practice
Boulder
Great
at, 145.
Han
Star
nan
Mine,
Diehl
103. 102. couple for zinc precipitation, precipitation,175. smelting, 115.
at,
process
177.
Goldfields,127, 133. consumption of cyanide at,
Hauraki
132, 133.
Company,
Homestake
Dakota,
Co.'s
of, 67. vats for, 48, 51. Lead, influence of, 13. tion, acetate, use of, in zinc precipita-
75.
Mercury Cyanide Works,
from, 87, 148.
ore
vats, 53. Langlaagte 109. 72, 57, practiceat, Leached residues, discharge of, 56. Leaching, 70, 76. by agitation,81, 82, 94, 96. Estate
cost
practiceat, 147.
Horseshoe,
Consols,
View
Lake
precipitation of, by zinc,
—
routine, 17.
Laboratory
of, 106. slimes, 107.
120,
154, 164. of, 35. Hydrocyanic acid, estimation poisoning by, 184. ing, Hydrogen, evolution of, in acid refin-
cost
of, 119. for, 116.
fluxes
cyanide, 6, 133. gold, on cupellation,119. Estate, practice at, Luipaards Wei Loss
of
of
125.
Lydenburg, precipitationpractice at, 105.
111. in in
leaching, 158. zinc precipitation,102,
104.
Forrest process, 1. frames filter Main at, 55. Reef, Malachite, influence of, 10, 13.
McArthur-
dioxide, influence of, 15. in acid refining, 111. Marlborough, N.Z., experiments at,
Manganese India, practicein, 169. sun-drying in, 92. Intermediate Iodine
18.
73. filling,
solution,
standardising,26. 13.
of, 7, of, 93. salts,influence of, 8, 9. Irvine's discharging doors, 58. Iron
pyrites,influence occurrence
Martin
press,
88.
vats, 53.
Masonry Melting gold slimes,
109.
Mercur, practice at, 162. Mercuric
chloride
solution,25.
191
INDEX.
Mercury couple, in
zinc
precipitation,
103. influence
of, 11.
of, 157, 181. in India, 169.
use
sulphides, influence of, 12. of filling vats, 72. Mineral acids,influence of, 7. Moanataiari, discharge doors at, 60. practiceat, 58, 89, 134.
Metallic Methods
vats
used
Monowai,
on
from,
ores
Protective
alkali,166. estimation
-
of, 44. of, 9.
blue, formation of
recovery
—
practiceat, 102, 133, 134, 180. of, at, 98. sulphides, treatment Montana, practiceat, 161. zinc precipitationat, 120. Montejus, 146, 151, 152. Malcolm Mount Proprietary, air-lift
Prussic
acid, liberation
ores,
7.
cyanide by, 75. testing for, 19. of, 70.
treatment
tailings, zinc Natural
precipitation of,
102.
Pyrolusite,influence Rand
Central
of, 15.
Reduction
Company's
plant, 84. Rate
at, 123.
of
extraction,
18.
of solution, 14.
Mexico, practicein, 161. South Wales, practice,151.
Reactions
involved, 4, 8,
Zealand,
Remedies
for
treatment
concentrate
94.
loss of
167.
settlement, 85. Nevada, practicein, 161. sun-drying in, 92. zinc precipitationin, 161. New Eleinfontein, tailings practice
of, 184.
Pumps for solutions, 63. Pyrites,influence of, 13, Pyritic concentrates, 93.
63.
Mysore Works, practiceat,
in,
cyanide from,
173.
81, 83.
at,
process, 180. for, 184.
Precipitation boxes, 175. by charcoal, 12, 120. by zinc, 100, 120. tanks, 61. Preliminary wash, 69, 75. Pressing cakes, 151.
Prussian
at, 52, 53.
experiments
cyanide Poisoning, antidotes Pneumatic
9.
poisoning, 186.
Residues, dischargeof, 56.
94.
practicein, 56,
Riecken
127.
Nickel, influence of, 15. Nitre, use of, in smelting, 107,
170.
process,
Robinson
Ohinemuki,
of
occurrence
gold at,
89, 145, 150, 181.,
Roasting before cyaniding, gold slimes, 107. Roche
Works,
89.
85.
dischargingdoors, 59,
137.
90.
practiceat, Order
Sands,
134.
Schilz
of operations, 71.
Ores, kiln-dried, 7, 12. testingof, 17. Oxidising agents, 69. Oxygen, influence of, 15. in working solutions, 41. Pan
amalgamation,
Park-Horn
Settlement,
from
180.
from
by,
Slime
at Crown
Mines,
96.
Phenolphthalein indicator,37. Plant,
cost
of, 67.
171.
cake
at, 52.
acid
refining,113. lead smelting, 119. smelting slimes, 109. pressing,140.
mixers, 151. Slimes-arrester, 167. refiningby sulphuric acid, 110. smeltingof, 107. sun-drying of, 92. —
vats, 51.
process,
Silver, influence of, 133. nitrate solution, 22. Simmer and Jack, vats used
Slags from
93.
71.
86.
Siemens-Halske
127.
Percentage extraction, 19, 20. Percolation, leaching concentrates plant
process,
179.
Separators, 86, 87. Sequence of operations,
180.
process, Whitaker process,
of, 91.
treatment
192
INDEX.
Slimes,
of, 80, 83, 92, 107,
treatment
Tavener
process,
115.
cost
of, 119.
110, 140. at
Waihi,
by
Tavener
acid
slimes,
gold slimes, Soda, Solution
161.
School
108.
acid
smelting
ol
Telluride
cyanide, acidity,34.
Tests
for
Threshis'
dutyinN.Z.,132. precipitation,
consumption method,
Titration
of slimes, 80.
Treatment of
the
tailings,on
Rand,
leaching, 76.
Strong solution Sulman-Teed
Sulphide —
of, 13. contrasted, 5.
of solutions
ores,
47.
constants,
Utah,
practicein, 162. precipitationin,
for solutions, 50.
Vats
construction
of, 52. iron, 51. wooden, 51, 67. 72, 81. filling,
of, by agitation,
extraction
98.
of, 149. influence of, alkaline, Sulphides, roasting, 148. Sulpho-cyanides,action of, 15. estimation of, 36. treatment
Sulpho-telluride ores, Sulphur, Sulphuric
acid
leaching 14.
of,
Victoria,
13.
filter frames
86, 99, 135. used
vats
Sun-drying, 84, 92,
Waikino,
161.
at, 51, 53, 57. plant at, 59, 62,
new
practiceat, solutions, 46. vats with, 72. filling Tailings, for, 19. test solutions 142. at Waihi, treatment, value of, on the Rand, 122. for assay
vats
Talisman
Ohinemuri,
at, 134.
dissolving, 50.
practice
122.
142.
Waitekauri, practiceat, 15, 131, Washes, 78.
144.
preliminary, 69. 78.
water, weak Washoe
52.
for, Mine,
62.
at, 55.
general practice at, 11, 56, 84,
of, 113.
Sumps, 60. washes, 77.
Tables
percolation,51. precipitation in,
120.
refining,110.
cost
and
charcoal
influence of, 15. Wad, Waihi, extraction practiceat,
144.
free, influence
120.
cylinders,55.
Vacuum
177.
process, 77.
123.
filtration,83.
Upward
125.
Strength
34.
solutions, 23,
zinc
vats, 54, 67. Stibnite, influence
18.
cyanide,
158.
standard
of
of
24.
Useful
zinc
for
30.
solutions, 22. strength of solutions,
124.
of, 22. weak, use of, 70. Sores, from cyanide poisoning, 186. South Dakota, practicein, 164. Spitzkasten, 72, 86, 140, 147. Spitzluten,86, 138, 139. Stamp batteries, 80.
Tank,
of, 144. 160. Creek, Cripple
crude
for
testing,19.
tanks
plant, 97.
treatment
ores,
Testing
63.
of, 4.
titration
Steel
of Mines
practice,at
vats, 50. Solutions, bulk of, 122, dilution of, 29. for
plant
concentration
Tell-tales, 63.
108.
pumps,
rate
79, 97,
at, 96.
107.
of, in
use
slimes,
133, 170. Goldfield,
115.
process,
Slimy sands, leaching, 79, tailings,66, 70. Smelting
Experimental Works,
Thames
140.
Weak
cyanide,
process,
78.
180.
solutions, precipitation from,
105.
Weights
and
measures,
47.
193
INDEX.
Western
Australia, practicein, 144,
Zinc
100.
consumption of, 101.
161.
sulpho-telluride ores,
Mining Company, precipitationat, 174. crushing, 80, 90, 120, 128.
inN.Z.,128. the Rand, 120. on losses on the, Witwatersrand, electrical
influeuce
of, 18. precipitation, 100, 120, 125. 120. cost of, in America, extractor boxes, 125. of influence copper on, 103,
6.
the,
104.
the, 56, 70, 72, 75,
103.
precipitation on
influence
171.
practiceon
acid, 110,
vats, 51. cost
lead
on,
102,
113.
slime
of, 67.
Mining Company, agitationpracticeat, 94, drying ores at, 75. Gold
smelting, 107,
Creek, Kirk, plant at,
PRINTED
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121, 171.
Woodstock
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Gold
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?.M.IN8V.1MCH.*.,
Head Institute, and Polytechnic of the Departments Engineering
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oomplbvb
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:
Use
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tixt-book, and
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of Students
arranged not
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contact
CHARLES
Wh.Sc,
GRIFFIN
on
an
in
the Department Engineering OoTlege, Yorkshire
London.
for
Technical
ixcillbxt
of
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btstbm,
Schools
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ft CO., LIMITED, EXETER
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CoNTBMTt.— tias Engine* Description— History and Develop* :— General for Motive Production German Gas Gas PowerBritish, French, and Engine*— of the Gas Chemical in Gaa of Gai Theory Utilisation of Engine Compoeition Engine*— Heat Combustion. and and Various Oil Explosion MOtOPS Development— :— History and Oil other DerekseHot-Alr TVpea— Pneetman's and Engines. Engines :— History Various Types: Ericsson's, etc., "c. awa*— Stirling's, taeat—
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orkat
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07
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:
CHARLES
Fuel
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fbzskmt
GRIFFIN
"
—
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Stations
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Testing Index. Bibliography
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Land,
—
during
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years,
Practice. Will
that and
Stokers
through Boiler Plates, Pumps, Superheaters, Feed in used Testing Boilers
made
uhiqus.
iron
Mechanical
—
Boiler, and
a
that
of boilers
ruurni
Boilers— Efficiencies
Heat
—
Appendices
performance
of
Types their
Heat
Testing
best Modern
the most "Probably xxhaustivb by a thoroughly practical man."—
LONDON
Types
Heaters,
Choice
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of
with
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On
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Evaporation,
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LOCOMOTIVE).
the
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OF STEAM
DONKIN,
Contents.
General
Combustion
and
BRYAN
Bv
in
Gases
of
monument
Lighting. Engineering.
Numerous
Experiments Value Heating
Suggestions
and
With
lowo
KNOWLEDGE,
»fG+s
—
AND
the
to
as
Analyses
shown
Cloth.
and
Tests
many
Boilers,
y*wn*l
of
advantage
Engintsr.
A
Treatise."
exhaustive
MARINE,
(LAND,
Ths
—
...
EFFICIENCY
HEAT
THE
"
work. —
themselves
SXFEKIMBMTAL
Engineers.
of
DonMn's
of
.
.
make
to
the
has
AND
SCIENTIFIC
requirements
Handsome
Quarto,
.
have
.
comprehensive."
and
ksliablb
.
HIGH
Mr.
.
.
In
425
of the
KBCOMMBND
labour.
.
Wtth
he
Will
Engines. who
Donkin
Mr.
day.
Combined
hxabtily
Air Gsj, Oil, and practioal engineers
on
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of
motor
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A
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"We
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GAS An
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CHARLES
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THE
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are
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AND
FOB
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LOCOMOTIVE A
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Modem
:
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—Index.
Likely
44
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years
Work
Standard
those
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wishing
learn
to
Design.'V~Bfirffefr. u
A
44
Interesting
most
ReHtwav
We
recommend
nAORix
am
"Tee will at
In
the
work
book
as
of
bibliography
the
to
the
Locomotors."—
all
that
oast
from
lrabut
bb
woes
ufox
ncronrAirr
ran
Cloth.
Handsome
Svo.
A its character, and Msarrnre Ifmct. Bngineeriiig."~£«tf«"ejr It smoh book a subjeot. a upon subjhot."— Rmihsaf Magaain*.
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oovtadts
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RAILWAYS
LIGHT HOME
AT By
WILLIAM Late
ABROAD.
AND HENRY
M.Inbt.O.E.,
OOLE, North-
Deputy-Manager,
Western
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India.
Con^to.— Discussion of the Term Railways, Light Railway*. "—English Fanners. in Italy, other France, Light Railways Belgium, Rates, and Road port Transthe Colonies, India, Ireland.— and Countries, America European of The alternatiye.— The Question Light Railways Act, 1896.— ae an Construction and Working. Locomotives and Rolling-Stock. light Gauge. Index. and Railways in England, Scotland, and Wales.— Appendices "(
—
u
Mr.
W.
H.
Oole
has
hitherto
txon .
44
Will
remain,
together
for
time
some
yet
to
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Standard
a
of yaluarlh
axouvt
labor
a
...
inaooessible
reader."—
ordinary Work
everything
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relating
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The
author
well
recommended
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of the
engineers
LONDON
:
is as
practical "—
BR
weloome
CHARLES
mo
experienoe amsin%string.
bxhacstitrlt
and
nmarsHSAHLB
to
necessities
prime
could
will
done.
subject
cordially "Tmsui
extended
has
It is RXCRRDnieLT 44 The whole
one
brought
practically
.
.
BaUwarB.''— 44
—
—
—
of the
BRTTRR
its appearance."
GRIFFIN
of
"
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makes
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whose future."— reference
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considered.
raAonoALLT
those
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LUBRICATION
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ARCHBUTT, Chemist
21
THE
AND
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A
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"
I.
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R
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Contents.—
Gbkkkal fective
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tks
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IUush-cUsd.
lIANAGrBJlCUNT,
of
The
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-
By
De
the
on
VoryfuUy
Edition.
Bnginssr
Methods
Industries
subject."— KVOWN
18
Railway
DXnOTS,
Cats/
the
on
THAT
STEAM THEIR
and
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Testing of Lubricants X. Testing of Lubricants.— of Machinery.— Ihpkx.
Lubrication
Destined
become
The
Systematic
"
F.G.S.,
Derby.
II.
IV.
VII.
The
M.I.M.E., Manager,
Works'
Friction or Liquid Viscosity, of Lubrication,— v. Theory and VI. Properties.— Physical Properties
and
—VIII.
XI.
Solids.—
Tension.—
Lubricants.—
IX.
Bearings.—
of
Friction
Superficial Preparation,
Sources,
Examination
Locomotive
Railway
Coll.
steam
lbs. per
engaged
Table
inch
square
about
of
and
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Bursting
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Boilers, ought
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Fifth
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GURDEN, of
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Instruments Used for Meteorological logical Meteoroat Sea Purposes.— Pressure. Sea Air Atmospheric Temperatures. Temperatures.— Winds. Wind Force Scales.— of Storms.— History of the Law Hurricanes, Seasons, and Tracks.— Storm Solution the Problem.— Ocean Currents.— of Cyclone Icebergs.— -Synchronous Charts.— and Haze.— Clouds.— and Hail.— Dew, Mists, Fogs, Rain, Snow, and Auroras.— Mirage, Bainbows, Coronas, Halos, and Meteors.— Lightning, Corposants, Appendix.— Index. Questions.—
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CHARLE8
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Gcuutte.
of Griffin's
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STRAND.
erer
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Edition,
Second
the
to By
by
and
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Crab
The
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book
of
Spar— Centre Floating Bodies
of .
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exoeedinolt
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of
amount
:
dec.
Ship's Pump,
large
;
the
of
Calculation
of
Effort
the ; a
;
Relative
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and
dons
The
Lever; Ship's Capstan Plane; the Screw— Strength of Rope
Windlass
Inclined
Cargo
Work
Forces—
of
Powsrs:
:
The
Coir—
a
Fir
Stability
Composition
The Man"—
"Old
of
and
Whsel
Hemp,
Strain
Diving-bell
the
Gravity
Manilla,
Gross-breaking
Agents— The
:
Sailor.
the
F.FLA.3.
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MACKENZIE,
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as
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Nature.
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Shipping "No
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from
to
and
frequently Ac., sec. spars,
to
(Letter
—
to
the
Author
With
Diagrams,
is
*#*
Mr.
the
New
would
.
.
reason
sate
all
BUCK,
H.M.S.
'
Worcester.1
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been
specially
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Price
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Corrected.
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a Teacher. opportunity of oonsalting therefore, have, simplest explanations
are
and contents, that to hoped Cadets
works
Algebra. They are been avoided, study, become by careful
little
have
but
Exercises
'—Schoolmaster.
of
Requirements
elementary
All
belt."
the
to meet
will
who
vomica'
billable
Manual
*,* These those
and
pbaotical
nmniTTLT
A
the
and Revised
has
of
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Edition,
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Buck's
.
Mariner).
C.
College,
taken
have
you
obligatory subject.
an
"This
the
RICHARD
Examples,
Second
Master
another
of
care
experience.
Mechanics'
'Practical
Training
Nautical
Thames
Manual
A
to
! from
and
life's
a
by rigging purchases
wasted
BY
WORKS of the
is
.
.
see
labour
the
for
you
It
we
accidents
this."
Mariner).
Mechanics.'
amount
an
much
how
me
Master
a
.
What
without be complete Notwithstanding many my there it to acquire."— more
Mechanics.'
Practical
thanks
my
Practical
'
helpful."—
henceforth
will
bookcase '
years' experience at sea, (Letter to the Publishers "
be
.
.
.
Officers'
Mackenzie's
Captain
in
will
money
World.
readily, further
mathematical
Mercantile
Marine
a
are
taken
from
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will
speoially
books
for
and
ahswbbs
master
be
m
of theii It la
decidedly Papers set fer
found
Examination
Worcester." and
arranged, Clearly Maganint.
well
got
up.
A
first-rate
Elementary
Algebca.
...
Ifautieai
%*For
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NAUTICAL
OMrrars Second
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WORKS.
43
nautical
Thoroughly Handsome
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Revised
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Cloth.
Price
Extended.
In
Crown
8to.
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THE LEGAL DUTIES OF SHIPMASTERS. BY
BENEDICT
WM. the
Of
Inner
GINSBURG, and
Temple
LL.D.
M.A.,
Northern
(Cantab.),
; Barriater-at-Law.
Circuit
The Position The of Shipmaster— tract ConQualification tor the The Master's in respect of the Grew : Engagement : Shipowner— Duty Medioal Gomf and orta ; Payment Apprentices ; Discipline ; Provisions, Aooommodation, The and Master's of wages Master's Discharge—The Duty in respect of the Passengers— Master's Financial The in Master's Sesponsibilities— Duty respect of the Cargo— The Authorities— The Public in Case Casualty— Master's certain The of to Duty Duty The Master's Master's to Pilots, Signals, Flait, and Light Dues— Duty Duty in relation Arrival relative at the Port of Discharge— to oertain : Legal Matters Appendioes upon Line SegulaBoard of Trade of Grain Cargoes, Load Certificates, Dietary Scales, Stowage at Sea, Me., Ac— Copious Index. Appliances, Carriage of Cattle ttons, LnVsaving
General
Contents.—
with
"
No
Master
Intelligent
ef it may "
the
says
Ssstsibia,
lall
in
Soerotarf
and
J.
MILLAR,
Marine
—
Second
and
comprising
A MEDICAL
on
prove
an
and
Plates
and
acquisition
olbajl"—
Numerous
Regulations Respecting Board Price 6s. Ship.
AND
the
SURGICAL
Th$
tions, Illustra-
Carriage
HELP
OFFICERS
AND
NAVY.
MERCHANT
THE
in Scotland.
SEA.
AT
SHIPMASTERS IN
simple
useful,
Coloured
latest
Stores
of Medical
FOR
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With the
but
.
AID
Revised.
Edition,
2a.
Engineer.
handy
FIRST
Shipbuilders cannot
.
.
studying Navigation." " will find it Seamen Young Snfftneer.
ef
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clearly
to those
ftnmd
them.
Inst, of Engineers
tho
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Longitude:
Find
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With
to
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Roviow.
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By
Concimly
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How
"
kok-tkohnigal
British
Latitude
A tew books. list of necessary of Common*. Liverpool Journal
bis
to
woebt."—
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clea*
Edition,
LaU
this
bxdlsss
by the Shipmaster."—
Second
add
to
BieiDae
m,
plainly written,
scBYien
iruon
should
lawykb's
?
BY
WM.
JOHNSON Principal
%* useful
The
attention
aad
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valuable
all interested
of
work.
\* LONDON:
judicious,
For
It
amongst
xzpbrts»cb
Sou**,
SMITH, Officer, Seamen'a
Medical
bjeally
Complete CHARLES
is
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oar
needless
Navy
Merchant to
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at
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form.*'
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clearness
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The
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Marine
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BY
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CHARLES
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AND
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MAN
MARINE By
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M.
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Part Marine Contents. I. Propulsion. Principles of of Details III. Part Principles of Steam Engineering. and Calculations for Marine Pistons, Valves, Cylinders, Engines : Design Boilers. Part V. "c. Part IV. Valves, Propellers. Expansion General
—
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IV.
—
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This
V
"
sad
In
a
Marine
far the "—
Engineer. "The
Manual
best
solving,
of
with
a
Student
GWes .
possible
with
Bureau
Veritae,
how
iearn
to
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the
economy,
Ilhvtr*
Boilers,
of the
Rules
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.
utmost
and
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Edition,
on
has
to
design,
conitruov
rital/'—
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Timu
account complete before the problems a
will find
Engineer
Marine
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of
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Reference
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and
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a
Types
oapaeity of enabling Mr. Steam-Engine,
three-fold
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.methods
leading
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of
work
"By
includes
Edition
tions
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Miscellaneous.
—
USB
AND
TABLES,
07
Naval Architects, Designers, and Others. Superintendents
Draughtsmen.
BY
A.
E.
M.I.O.E.,
SEATON,
M.I.Mech.E.,
M.LN.A.
AND
fl.
M.
ROUNTHWAITE, "Admirably
DOCKS:
its
fulfils
By
B.
purpose."
—
THEIR CONSTRUCTION
:
CHARLES
GRIFFIN
Marine
Engmttr.
OUNNINGH'AM.
(See LONDON
M.LN.A
M.LMech.E.,
A
page
" MAINTENANCE.
27.)
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For
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"
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foi
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The
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in
Al
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will
It
road
tablb
OR
Different
of Engineer*,
us*
collection time
hard
French)
Mutual
Horse
In
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actual
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a
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Showing
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bbbbbbvcb
MEASUREMENT
28
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in rendering serviceable and Athenanm. Engineer."—
complin
tbbt
B.Sa,
Lecturer
College.
Diagrams
will be Student
book
.
4BL1
with
extra,
E. H. Smith's Paof for the non-mathematical
and
UniYareity,
Maaon
"
SMITH.
BT
MUIRHEAD,
F.
INTEGRALS.
OF
H.
ROBERT ASSISTED
R.
ENGINEERS
PHYSICISTS,
Applied
By
Assoc.M.I.C.i, M.Ord.MeiJL
Sch.,
FOR
AND
CLASSIFIED
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Whit
CALOULUS
THE
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OO.'S
6
the
of
chances
the
henceforth
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error
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in
and
prehensive com-
much
use
calculation
Office
will
be
Guardian. even
occasional
chicks
on
conTersions
are
required.
Praf. .
results."—
Electrical
.
.
Review.
"
the but of the Commbbciai. Prof. Smith deeerres hearty thanks, not only of the Eireivnia, of Mbasubbmbbiy for the Syitbm for haying smoothed the way of the Msrmio Wobxd, adoption in factor which is now great hobb assuming a maintaining importance a subject as our upon The tbabb."— Market. Mmehinery fOBUiov
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44
"
IV. VI.
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mamutaoturb,
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USES.
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The
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There
have
who
.
UTILISATION.
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Grease
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Surveyors,
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ITS
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own
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prove
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years,
Samitaby
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to
mm
»
Cost.
and
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WW
Woass
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Scsenoe
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Aim moot
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far
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iimrislsl be
Sootion
Northern
many
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Aether's
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pbacticai.
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feet
Works
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nTU
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V
ntoaenage
Sbwaos
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Tmeii
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County
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CRIMP, AMMtaat-BngVMer,
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"
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ELECTRICAL STATIONS:
Design, Organisation, H.
49
Work
Station
Profession.
a
as
As
—
Investment.
an
lishment Estab-
The
—
Site.— Architecture. Plant. Boilers Supply. Coal Handling, Weighing, and Heat Economy. Storing. Systems of Draught and Waste Generators. The Transmission of Steam. Condensing Appliances. Switching Gear, Distributing Mains. Insulation, Resistance, and Cost. Instruments, and Connections. Mains and Meters Feeders. and Service Testing Mains. Distributing Networks Street ingLightSecondary Batteries. Appliances. Standardising and Testing Laboratory Mains Installation Cost General Organisation Department. Department. Clerical Office The Consumer. Drawing Department Standardising Department. Routine Index. and MainLaying. of
Central Station
a
of
Systems
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
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