INTRODUCTION
BULK CARRIER
A bulk carrier, bulk freighter, or bulker is a merchant ship specially designed to transport unpackaged bulk cargo, such as grains, coal, ore, and cement in its cargo holds.There are various ways to define the term bulk carrier. As of 1999, the International Convention for the afety of !ife at ea defines a bulk carrier as "a ship constructed with a single deck, top side tanks and hopper side tanks in cargo spaces and intended to primarily pri marily carry dry cargo in bulk# an ore carrier# or a combination carrier." $owever, most classification societies use a broader definition where a bulker is any ship that carries dry unpackaged goods. The first speciali speciali%ed %ed bulk bulk carrier carrier was built built in 1&'(, 1&'(, econom economic ic forces forces have have fuelled fuelled the development of these ships, causing them to grow in si%e and sophistication. Today)s bulkers are specially speciall y designed to ma*imi%e capacity, safety, safety, efficiency, and to be able to withstand the rigorous of their work. Today, bulkers make up +- of the world)s merchant fleets and range in si%e from single hold minibulkers to mammoth ore ships able to carry +, metric tons of deadweight /0T2. A number of speciali%ed designs e*ist3 some can unload their own cargo, some depend on port facilities for unloading, and some even package the cargo as it is loaded. 4ver half of all bulkers have 5reek, 6apanese, or Chinese owners and more than a 7uarter are registered in 8anama. orea is the largest single builder of bulkers, and &(- of these ships were built in Asia.
Literature Review
Bulk Carrier Types Types
4re Carriers 4re carriers are specially designed and may only be employed for a specific trade, eg carriage of iron ore in bulk from ma:or Australian or ;ra%ilian ports to specific ports in China or
6apan.hips that are designated as ore carriers have to be strengthened by class standards. In a seaway these ships tend to be stiffer due to the high density of ore cargoes. 4il<;ulk<4re 4;4 hips These ships were designed to alternate between dry bulk and oil cargoes, avoiding a non earning ballast passage by carrying both cargoes in the same cargo spaces at different times. They were designed with large hatches to facilitate loading and discharging. $owever, the hatch covers were designed to be =oil tight) so the same ship could be loaded with oil cargoes with strengthened holds for ore cargoes. >or this dual purpose operation, 4;4s were fitted with with pipeli pipelines, nes, pumps and other oil tanker tanker e7uipm e7uipment ent.. ?a:or ?a:or proble problems ms on these these ships ships included gas freeing to load dry cargo after an oil cargo and the high maintenance costs caused by heavy wear and tear. 4wing to the number of losses, notably the ;erg Istra /19@2, ;erg Banga /19@92 and the 0erbyshire /19&2, combined with the high maintenance costs, there has been a reduction in the number of these ships, with few new 4;4s built. ?ost remaining 4;4s are limited to one cargo type. 4;4 construction construction is similar to that of a bulk carrier e*cept that they have larger wing tanks and their 0; tanks are deeper to improve stability when carrying ore cargoes. ?any 4;4s have void spaces formed by fitting transverse bulkheads between two cargo holds.
4ther features of 4;4s are3 1
4il tigh tightt hatch hatch cover coverss to allow allow the the carriag carriagee of li7ui li7uid d cargo cargoes es
(
0ed 0edicat icated ed slop slop tank tankss
8ump 8ump room room for for load load
+
Inert ga gas sy system
'
Tank
8ipeline 8ipeline system system /ballast, /ballast, bilge and cargo2 cargo2 fitted fitted through through the duct duct keel keel
@
;ilge lines /for use with dry cargoes2
elfEnloader ;ulk Carriers imilar in hull structure to other bulk carriers, these vessels are fitted with one of two systems for discharging cargo3 i2 A gravity fed selfunloader3 the cargo is dropped onto a conveyor belt running in a duct keel under the cargo holds that carries the cargo towards the bow or stern of the vessel where another conveyor lifts it for discharge ashore. The discharging arm is connected to a boom that can be slewed into position for discharge ii2 A hybrid selfunloader3 commonly used, this method does not re7uire any special structural design of the vessel. The cargo is discharged by grabs into hoppers where it feeds onto a conveyor belt. The hoppers can be permanently fitted on the ship or may be placed on the deck of the vessel when discharging. These ships can discharge cargo in ports without any unloading facilities. The discharging rates achieved can be the same or higher than those of similar shore based facilities. An added advantage is that a totally enclosed conveyor system can discharge cargoes such as cement, coal, grain, ores and fertili%ers without causing problems such as dust, cargo wastage, or damage to the ship)s structure by grabs or weather effects. hile the initial cost may be high and the ship)s carrying capacity is reduced by fitting an unloader, this is offset by the 7uick turn around and reduced port stay.
4pen $atch ;ulk Carriers /4$;Cs2
These vessels do not have upper and lower wing tanks. Instead, they have straight sides to carry s7uare shaped bundles of forestry products such as unitised wood pulp, rolled paper or packaged timber cargoes. They can even carry twenty foot containers. They may have fi*ed or travelling gantry cranes for loading
>orest 8roduct Carriers 4pen $atch ;ulk Carriers /4$;Cs2 can also be regarded as a forest product carrier, this collective term generally refers to the following ship types3 •
oodchip Carriers These vessels are designed to carry woodchips /shredded wood2 in bulk. oodchip is described as a =neobulk) cargo that re7uires methods and precautions similar to those for bulk cargoes. They are usually constructed with watertight /in contrast to weathertight2 cargo holds to prevent water ingress. This is particularly important as contact with water causes woodchips to e*pand and could cause severe damage to the structure of the ship. Additional security measures to prevent water penetration through air pipes and ventilation ducts to cargo compartments are also incorporated to protect the cargo.As the cargo holds fill, bulldo%ers are used to press the cargo. ome ships are fitted with cargo
loading< unloading e7uipment including cranes, grab buckets and wings with conveyor belts on deck /to pour the chips into cargo holds2. hen discharging, the ship)s cranes are used together with a grab bucket system running at the bottom of the cargo compartments. The cargo is carried to the forecastle by conveyor, where it is discharged ashore through a single discharging point. $owever, many ships use conventional grabs to discharge the cargo. •
Timber Carriers These vessels are used for carrying timber or logs in the holds and on deck. The machinery space and accommodation are located aft to provide clear deck space for the cargo. 5enerally, they are fitted with cranes that can handle logs that weight up to (' tonnes. This means that the decks, tanktops, hatch covers and other structures are additionally strengthened to withstand these loads.
These ships usually have fi*ed or portable uprights to support logs< timbers lashed on deck. It must be ensured that there is clear access to the mast houses, sounding pipes, etc, during loaded voyages. These vessels carry lashings that include turnbuckles, wire ropes, chain, etc, fitted with a 7uick release mechanism such as a senhouse slip to release the deck cargo in case of emergency. 4n some ships, air powered =speedlashings) automate the lashing and tightening procedure. The ship)s lashing plan should be adhered to as prescribed in the approved cargo loading manual. The Code of afe 8ractice for hips Carrying Timber 0eck Cargoes should be complied with for the carriage of timber on these ships.
•
ood 8ulp Carriers ood pulp from soft trees such as pine, larch, hemlock, fir and spruce is the most common material used to make paper. The ma:or ha%ard of wood pulp cargo is that it swells if it comes into contact with water, e*erting enormous pressure on the structure of the cargo hold and possibly causing a structural failure. Additionally, this cargo depletes o*ygen from the environment and generates carbon dio*ide, making the atmosphere in the hold unsuitable for entry. Considerable attention is re7uired to avoid contamination of the cargo by dirt or by residues of the previous cargo. ood pulp is typically carried in bales that have a protective covering to avoid any contamination to the cargo. To assist in the protection of a wood pulp cargo, holds are fre7uently repainted. Air bags are used to prevent the movement of bales in the hold.
•
$ybrid Configuration /$yCon2 ;ulk Carriers A recent advancement in bulk carrier design is the =hybrid configuration) or =$yCon). In this design, the most forward and most aft holds have a double skin but the other parts of the ship still have a single skin . In this way, the areas that re7uire additional protection are strengthened without greatly increasing the lightship weight.
A double skin enhances safety, security, dependability, reliability, and reduces the possibility of damage from accidental flooding. In addition, structures such as frames and brackets located inside the double skin structure provide a smooth surface for the cargo, reducing problems with inspection or maintenance. The potential for damage caused by cargo gear like grabs or bulldo%ers is reduced, increasing the speed of cargo discharging in port. The double hull makes inspection much easier through the use of passageways, ladders and manholes in the double skin. ;allast capacity is also increased, which is an added advantage in ballast voyages.
Various Bulk Carrier Sizes
Bulk carrier sizes Terminology Size D!T" C#aracteristics ?inisi%e between and It has less than five holds
Ty$ical Cargo ?inor bulk,
$andysi%e
(', between
!akesi%e
and +, between (, to pass through t. !awrence
(', It usually contain five holds
(@,
eaway which calls for a
$andyma*
between
draught limit of @.9(' m It usually contain five holds
8anama*
and , between ,
It usually
and 1, tonnes
holds.
+,
have
ma*.
breadth of about (.( m that can pass through the 8anama
Canal in present
state. 4nce the e*pansion is done,
scheduled
to
be
completed in (1', these locks will have chambers +(@m /1,+)2 long by ''m /1&)2 wide, and 1&.m /)2 deep.
products,5eneral Cargo. ?inor bulk, teel products
?inor
bulk,
teel
5rain, Coal contains seven ;au*ite, Coal,
These
teel
8hosphate
products,
5rain,
4re,
8ost
between
8anama*
Capesi%e
&, It usually contains nine holds. These are wider than and 1(, 8anama*es and with dimensions suitable for transiting the new locks of the e*panded 8anama Canal e*pansion scheduled to be completed in (1'. These locks will have chambers +(@m long by ''m wide, and 1&.m deep. between 1, It usually contains nine holds. and (,
Coal, 4re
uch ships are often described as Capesi%e, since if they are traveling from Asia to Furope but do not intend to use the ue% Canal, they will sail around outh Africa)s Cape of 5ood
$ope.
These large bulk carriers are gearless, that is to say they have no derricks or cranes and depend
entirely
on
shore
appliances for loading and discharging. This is because in most places where such cargoes
are
handled
the
terminals have very advanced machinery designed for the 7uickest possible loading or B!;C /Bery 4ver (,
discharging. It usually contain nine holds.
!arge
These large bulk carriers are
Carriers2
;ulk
gearless, that is to say they have no derricks or cranes and depend
entirely
on
shore
Coal, 4re
appliances for loading and discharging. This is because in most places where such cargoes
are
handled
the
terminals have very advanced machinery designed for the 7uickest possible loading or discharging.
%& C#oosing a Design'
The history of ship design is one of evolution rather than revolution. 0esigners learn from past e*perience and each new ship tends to be a development of a previous successful desi gn. The characteristics desired by the shipping company can usually be achieved with various combinations of dimensions. This choice allows an economic optimum to be obtained whilst meeting company re7uirements. An iterative procedure is needed when determining the main dimensions and ratios. %&% Single #ull vs& Dou(le #ull'
A double hull bulk carrier can be defined as a ship designed for the carriage of oil mainly in bulk where the cargo spaces are protected from the environment by a double hull consisting of double side and double bottom spaces dedicated to the carriage of ballast water.
Ability to prevent or reduce oil spills led 0; $E!! being standardi%ed for other types of ships including ;ulk carriers by the International Convention for the 8revention of 8ollution from hips or ?AG84! Convention.
After the F**on Balde% oil spill disaster, when that ship grounded on ;ligh Geef outside the port of Balde% in Alaska, the E 5overnment re7uired all new oil tankers built for use between E ports to be e7uipped with a full double hull. $owever, the damage to the F**on Balde% penetrated sections of the hull /the slops oil tanks2 which were protected by a partial double hull. The double hull re7uired by the new regulations would not have prevented e*tensive loss of oil from the F**on Balde%, though it might have somewhat limited the losses. >urthermore, a doublehulled ;ulk carrier doesn)t need longitudinal bulkheads for longitudinal strength, as the inner hull already provides this. Fliminating longitudinal bulkheads would result in much wider tanks, significantly increasing the free surface effect. $owever, this problem is easily corrected with the addition of antislosh baffles and partial bulkheads
)& Design Criteria'
o to satisfy the ownerHs re7uirements the dimensions of a ship should be coordinate such that the ship satisfies the design conditions. $owever, the ship should not be larger than necessary. The design should offer smarter shipping by reducing fuel costs with an optimi%ed hull form, and by increasing revenues with greater cargo capacity.
It has been said that the problem for a aval Architect is to design a ship that will carry certain deadweight at a reasonable rate of stowage in a seaworthy vessel at a predetermined speed on a given radius of action as cheaply as possible all in con:unction with a 5eneral Arrangement suited to the shipHs trade. The aval Architect must therefore keep in mind all of the following3
In determining the ?ain 0imensions for a new ship, guidance can be taken from a similar ship for which basic details are known. This is known as a Jbasic vesselH and must be similar in type, si%e, speed and power to the new vessel. It is constantly referred to as the new design is being developed. hen a ship owner makes an initial en7uiry, he usually gives the shipbuilder four items of information3 K Type of vessel K 0eadweight of the new ship K re7uired service speed K Goute on which the new vessel will operate
PLANNING, CONTROL OF CARGO LOADING AND UNLOADING OPERATIONS
Collecting cargo and Port Information
The safe operation of bulk carriers is dependent on not e*ceeding allowable stresses in the cycle of loading, discharging, ballasting and deballasting. To prepare the vessel for cargo stowage and a safe planning, the loading and unloading se7uences and other operational matters should be informed well in advance.
The shore terminal should provide the ship with the following information3
i2 8rior to loading bulk cargo, the shipper should declare characteristics L density of the cargo, stowage factor, angle of repose, amounts and special properties. ii2 Cargo availability and any special re7uirements for the se7uencing of cargo operations. iii2 Characteristics of the loading or unloading e7uipment including number of loaders and unloaders to be used, their ranges of movement, and the terminal)s nominal and ma*imum loading and unloading rates, where applicable. iv2 ?inimum depth of water alongside the berth and in the fairway channels. v2 ater density at the berth. vi2 Air draught restrictions at the berth. vii2 ?a*imum sailing draught and minimum draught for safe manoeuvring permitted by the port authority. viii2 The amount of cargo remaining on the conveyor belt which will be loaded onboard the ship after a cargo stoppage signal has been given by the ship. i*2 Terminal re7uirements
The ship)s ?aster should be aware of the harmful effects of corrosive and high temperature cargoes and any special cargo transportation re7uirements. hip ?asters, deck officers, charterers and stevedores should be familiar with the relevant I?4 Codes /for e*ample, the I?4 Code of afe 8ractice for olid ;ulk Cargoes, the I?4 Code of 8ractice for the afe !oading and Enloading of 0ry ;ulk Carriers and the 4!A Convention2. Deising a Cargo !to"age Plan and Loading#Unloading Plan
F*ceeding the permissible limits specified in the ship)s approved loading manual will lead to overstressing of the ship)s structure and may result in catastrophic failure of the hull structure. The amount and type of cargo to be transported and the intended voyage will
dictate the proposed departure cargo and
12 There are two stages in the development of a safe plan for cargo loading or unloading3
a2 tep 13 5iven the intended voyage, the amount of cargo and
b2 tep (3 5iven the arrival condition of the ship and knowing the departure condition /stowage plan2 to be attained, devise a safe loading or unloading plan that satisfies the imposed structural and operational limits.
(2 In the event that the cargo needs to be distributed differently from that described in the ship)s loading manual, stress and displacement calculations are always to be carried out to ascertain, for any part of the intended voyage, that3
a2 The still water shear forces and bending moments along the ship)s length are within the permissible eagoing limits.
b2 If applicable, the weight of cargo in each hold, and, when block loading is adopted, the weights of cargo in two successive holds are within the allowable eagoing limits for the draught of the ship. These weights include the amount of water ballast carried in the hopper and double bottom tanks in way of the hold/s2.
c2 The load limit on the tanktop and other relevant limits, if applicable, on local loading are not e*ceeded.
2 The consumption of ship)s bunkers during the voyage should be taken into account when carrying out these stress and displacement calculations.
+2 hilst deriving a plan for cargo operations, the officer in charge must consider the ballasting operation to ensure3
a2 Correct synchroni%ation with the cargo operation.
b2 That the deballasting
c2 That ballasting and deballasting of each pair of symmetrical port and starboard tanks is carried out simultaneously.
'2 0uring the planning stage of cargo operations, stress and displacement calculations should be carried out at incremental steps commensurate with the number of pours and loading se7uence of the proposed operation to ensure that3
a2 The > and ;? along the ship)s length are within the permissible $arbour limits.
b2 If applicable, the weight of cargo in each hold, and, when block loading is adopted, the weights of cargo in two ad:acent holds are within the allowable $arbour limits for the draught of the ship. These weights include the amount of water ballast carried in the hopper and double bottom tanks in way of the hold/s2.
c2 The load limit on the tanktop and other relevant limits, if applicable, on local loading are not e*ceeded.
d2 At the final departure condition, the > and ;? along the ship)s length are within the permissible eagoing stress limits.
2 0uring the derivation of the cargo stowage, and the loading or unloading plan, it is recommended that the hull stress levels be kept below the permissible limits by the greatest possible margin. A cargo loading
i2 The 7uantity of cargo and the corresponding hold number/s2 to be loaded
ii2 The amount of water ballast and the corresponding tank
iii2 The ship)s draughts and trim at the completion of each step in the cargo operation.
iv2 The calculated value of the still water shear forces and bending moments at the completion of each step in the cargo operation.
v2 Fstimated time for completion of each step in the cargo operation.
vi2 Assumed rate/s2 of loading and unloading e7uipment.
vii2 Assumed ballasting rate/s2
The loading
The loading or unloading plan should only be changed when a revised plan has been prepared, accepted and signed by both parties. !oading plans should be kept by the ship and terminal for a period of si* months.
A copy of the agreed loading or unloading plan and any subse7uent amendments to it should be lodged with the appropriate authority of the port tate.
The more commonly adopted cargo distributions are3 • • • •
$omogeneous hold loading conditions, Alternate hold loading conditions, ;lock hold loading conditions, 8art hold loading conditions.
%&*omogeneous #ol+ loa+ing con+itions'
)&,lternate #ol+ loa+ing con+itions'
-&Block./art #ol+ loa+ing con+itions'
T0/1S O2 C,R3O
0ry bulk cargo is shipped in large 7uantities and can be easily stowed in a single hold with little risk of cargo damage. 0ry bulk cargo is generally categori%ed as either ma:or bulk or minor bulk. ?a:or ;ulk Cargo
?a:or bulk cargo constitutes the vast ma:ority of dry bulk cargo by weight, and includes, among other things, iron ore, coal and grain & The ma:or bulk cargos and its specific gravity are as follows3
!pecific Type of cargo
!u$ Categories
Density
%raity
(1 12 Iron 4re
+ (+
(.1(.9 .+ (.+
dry Iron sulphate pickling tank
1(
1.(
wet
1(9
1.(9
(2 Coal
Charcoal Coal, Anthracite, solid Coal, Anthracite, broken Coal, ;ituminous, solid Coal, ;ituminous, broken
(& 1' 11' 1+ &
.(& 1.' 1.1' 1.+ .&
25rains
Gice, hulled Gice, rough Gice grits
@' '@@ &9
.@' .'@@ .&9
heat heat, cracked ;uckwheat
@9 @ '@ @&
.@9 .@ .'@
5rain heat >lour, wheat
& '9
.@&.& .'9
ugar, brown ugar, powdered ugar, granulated ugar, raw cane ugar beet pulp, dry ugar beet pulp, wet ugarcane
@(1 &1 &+9 91 (& '1 (@(
.@(1 .&1 .&+9 .91 .(& .'1 .(@(
Corn, on the cob Corn, shelled Corn, grits
@(1 @(1 @
.@(1 .@(1 .@
;arley 5rain ;arley
9
.9 .
4ats 4ats, rolled
+( +
.+( .+
Gye
@'
.@'
@'
@'
+2 coarse 5rains
Iron ore crushed Iron o*ide pigment Iron 8yrites Iron sulphate pickling tank
b
h l
(9
?inor ;ulk cargo3 ?inor bulk cargo includes products such as agricultural products, mineral cargoes /including metal concentrates2, cement, forest products and steel products M%4)4-456& The minor bulk cargos and its specific gravity are as follows3
!pecific Type of cargo
!u$ Categories
12cement
Cement clinker Cement, 8ortland Cement, mortar Cement, slurry
(2>orest 8roducts
ood ood chips dry Afromosia Apple Ash, black Ash, white Aspen ;alsa ;amboo ;irch /;ritish2 Cedar, red Cypress 0ouglas >ir Fbony Flm / Fnglish 2 Flm / ych 2 Flm / Gock 2 Iroko !arch !ignum Bitae ?ahogany / $onduras 2 ?ahogany / African 2 ?aple 4ak 8ine / 4regon 2 8ine / 8arana 2 8ine / Canadian 2 8ine / Ged 2 Gedwood / American 2
Density
%raity
1(91'+ 1' (1( 1++(
1.(91.'+ 1.' (.1( 1.++(
(+ '( @' & '+ @ +( 1@ + @ & '1 ' 9 11( 9 &1' '' '9 1(& 1@ '+' +9' &' @'' '9 9 ' ' ' ' @ +'
.(+.'( .@' ..& .'+ .@ .+( .1@ ..+ .@ .& .'1 .' .91.1( . .9 .&1' .'' .'9 1.(&1.@ .'+' .+9'.&' .@'' .'9.9 .' .' .'.' .@. .+'
2Agricultural 8roducts
+2?ineral Concentrates
Gedwood / Furopean 2 pruce / Canadian 2 pruce / itka 2 ycamore Teak illow Cottonwood Coffee Coffee, fresh beans Coffee, roast beans cotton Cottonseed, dry, delinted Cottonseed, dry, not delinted Cottonseed, cake, lumpy Cottonseed, hulls Cottonseed, meal Cottonseed, meats 4il seeds 4il cake 4il, linseed !inseed, whole !inseed, meal ;au*ite, crushed Alumina copper Copper ore Copper sulphate, ground
'1 +' +' '9 @( +( +1
.'1 .+' .+' .'9 ..@( .+( .+1
'1 +(
.'1 .+(
'1 ( @ 19( '9 +1
.'1 .( .@ .19( .'9 .+1
@&' 9+( @' '1 1(&1 91 &9 19+('9 +
.@&' .9+( .@' .'1 1.(&1 .91 &.9 1.9+(.'9 .+
11+ 11&9 &+ +&'
11.+ 11.&9 .&+ +.&'
%inc %inc o*ide
@1' +
@.1' .+
?agnetite, solid / iron ore 2 ?agnetite, broken
'+ (&+
'.+ .(&+
!imonite, solid !imonite, broken !imestone, solid !imestone, broken !imestone, pulveri%ed
@9 (+@ (11 1''+ 19+
.@9 (.+@ (.11 1.''+ 1.9+
(+ '1'
(.+'.1'
lead !ead, rolled !ead, red !ead, white pigment
8yrite /fool)s gold2
'2Nteel 8roducts
steel rolled steel stainless
2Agricultural upplies
8hosphate 5ypsum, solid 5ypsum, broken 5ypsum, crushed 5ypsum, pulveri%ed
@2Commercial 8roducts
8otash urea wool leather
@&' @+& &
@.&' @.+&&
1@( (@&@ 1(91 1( 11(1
1.@( (.@&@ 1.(91. 1.( 1.1(1
1(&1 @'@&' 11+ 9+'
1.(&1 .@'.@&' 1.1+ .9+'
A5!F 4> GF84F3 The angle o7 re$ose or the critical angle o7 re$ose , of a granular material is the steepest angle of descent or dip of the slope relative to the hori%ontal plane when material on the slope face is on the verge of sliding. This angle is in the range OP9O. Ty$e o7 Cargo
,ngle o7 Re$ose
Iron ore crushed
'
Iron sulphate dry
++
Iron sulphate wet
++
Charcoal
'
Coal, Anthracite, broken
(@
Coal, ;ituminous, broken
'
Gice, hulled
++
Cement clinker
@'&'
Cement, 8ortland
++
Cottonseed, cake, lumpy
++
Cottonseed, meal
'
Cottonseed, meats
++
4il cake
+'
8hosphate
('(9
5ypsum, broken
+
T4A5F >ACT4G3
In shipping, the stowage 7actor indicates how many cubic metres of space one metric tonne /or cubic feet of space one long ton2 of a particular type of cargo occupies in a hold of a cargo ship. It is calculated as the ratio of the stowage space re7uired under normal conditions,
including the stowage losses caused by the means of transportation and packaging, to the weight of the cargo.The stowage factor can be used in ship design and as a reference to evaluate the efficiency of use of the cargo space on a ship.
Ty$ical Bulk Cargoes
Commo+ity
Stow 7actor4 7t-.longton Stow 7actor4 m -.longton S$ec& g4 ton.m-
Iron ore
1(1'
.+ P .+(
(.+(
Coal
+(+&
1.(1.
.&'.@'
5rain heavy
+('
1.(1.+(
.&'.@(
5rain light
''
1.'1.@
.'.
;au*ite
(&'
.@9.99
1.(91.
8hosphate
+
.91.9
1.1(1.
5eneral
(+(9
.9.&(
1.+@1.(+
