Production Drilling in Underground Mining
First edition 2008
www.atlascopco.com
We always take a hard view on costs
Working with Atlas Copco means working with highly productive rock drilling solutions. It also means sharing a common cost-cutting challenge. Like you, we are always looking for new and effective ways to squeeze your production costs – but never at the expense of quality, safety or the environment. Mining and construction is a tough and competitive business. Fortunately, our view on cutting costs is just as hard. Get your free copy of Success Stories at www.atlascopco.com/rock
Committed to your superior productivity.
Atlas Copco Rock Drills AB Fax: +46 8 670 7393
www.atlascopco.com
Contents Foreword 2 Foreword by Mikael Ramström, Product Line L ine Manager, Manager, Underground Drilling Equipment Atlas Copco Rock Drills AB
Talking technically 3 Percussive rock drilling 9 In-The-Hole (ITH) vs tophammer drilling in underground mining long straight holes 13 Drilling long Automated ed long long hole drilling 19 Automat pace 27 Faster Simba rigs set the pace 33 Increased productivity with ITH drilling 37 Tu Tuning ning up your drilling system 39 Computer based training for rock drilling tools 41 The economic case for routine bit grinding
Case studies 45 Exploring the potential of El Aguilar 47 Increasing drilling rates at Ridgeway Ridgeway 49 Sub level caving caving for chromite at Ferbasa 53 Firs Firstt Cabletec cable cable bolting rig in in South America 55 Innovative mining at Garpenberg 61 Automat Automated ed longhole longhole drilling with Simba at LK LKAB AB
Product specifications 65 Modular program with maximum flexibility 67 Tophammer drill rig specifications 78 Hydraulic rock drill specifications specifications 79 Tophammer drilling equipment 100 ITH drill rig specifications specifications 104 ITH rotation units 105 ITH drilling equipment 107 Rod Handl Handling ing System (RHS) 108 Hydraulic feeds 109 Drill rig options 110 Secoroc grinding 118 Rock drill specifications 119 Complementar Complementaryy equipment 124 Lubrication 125 Service workshops 126 Conversion table
Front cover: Simba M7 C production drilling rig at the Garpenberg mine, Sweden.
Produced by Atlas Copco Rock Drills AB, SE-701 91 Örebro, Sweden, tel +46 19 670 70 00, fax 019-670 73 93.Publisher: Ulf Linder,
[email protected] Production Manager: Anna Dahlman Herrgård,
[email protected]: Mike Smith,
[email protected] Senior Adviser: Hans Fernberg,
[email protected] Contributors: Alf Stenqvist, Björn Samuelsson, Bo Persson, Fredrik Öberg, Hans Fernberg, Leif Larsson, Patrik Ericsson, all name.surn
[email protected] [email protected]. o.com. Craig Griffiths, craig.g craig.griffiths@ riffiths@ lkab.com Håkan Schunnesson,
[email protected],
[email protected], Kyran Casteel, k yrancaste
[email protected].
[email protected]. Digital copies of all Atlas Copco reference editi ons can be ordered from the publisher, address above, or online atwww.atlascopco.com/rock. www.atlascopco.com/rock. Reproduction of individual articles only by agreement with the publisher. Edited by Mike Smith, tunnelbuilder ltd, United Kingdom.Designed and typeset by ahrt, Örebro, Sweden. Printed by Prinfo Welins Tryckeri, Sweden. Legal notice © Copyright 2008, Atlas Copco Rock Drills AB, Örebro, Sweden. All product names in this publication are trademarks of Atlas Copco. Any unauthorized use or copying of the contents or any part thereof is prohibited. This applies in particular to trademarks, model denominations, part numbers and drawings. Information in this publication is provided “as is”. Atlas Copco Rock Drills AB disclaims any representation or warranties of any kind including without limitation warranties of merchantability or fitness for a particular purpose, non-infringement or content. In no event will Atlas Copco Rock Drills AB be liable to any part y or any damages for any use of this publication. T he contents, including illus trations and photo s, in this publication may describe or show equipment with op tional extras . It may also contain references to products or services tha t are not available in your country. This publication, as well as specifications and equipment, is subject to change without notice. Consult your Atlas Copco Customer Center for specific information.
PRODUCTION DRILLING IN UNDERGROUND MINING
1
Foreword Welcome to our first reference edition focusing on production drilli ng. This book is derived from our series entitled Underground Undergro und Mining Mini ng Equipment following following the recent dramatic growth in the importance impor tance and sophistication of production drilling. With the rise in demand for most most minerals, mining companies are having to respond with rapid increases i n safe production, both to satisfy their customers and to maximize profits after a prolonged period of price stagnation.
Atlas Copco, as a world leader in the t he manufacture and suppl supply y of mining equipment, is meeting the challenge with the Simba series of highly efficient drill rigs to suit various underground
production situations. situations. These rigs r igs incorporate the latest lat est RCS computerization techniques and their modular design allows customers to specify the drill unit, un it, feed length, rockdrill, and optional equipment to suit suit a variety of drill dri ll patterns. A whole range of compatible tophammer and Secoroc ITH equipment
The trend to faster drilling is accompanied by higher productivity, while improved accuracy with less hole deviation ductivity, means the hole bottom is closer to the preplanned coordinates, leading to better ore recovery and less waste dilution. For room-and-pillar room-and-pillar and similar simi lar lateral mining m ining techniques we produce a range of Boomer rigs, while for smaller operations
where compressed air may be the only available power, we still produce our handheld pusher rock drills.
When designing, manufacturing, selling and servicing Atlas Copco equipment, we rely on our long heritage to produce high-productivity machines that achieve the best return on customer investment. Our worldwide presence through offices in over 130 countries ensures that we are a re close to our customers, sharing their problems and understanding their methods
and applications. Their inputs are crucial to our engineers, whose job is to continuously develop our products and systems in order to maintain our market leadership.
is available, including shanks, drill dril l string stri ng and bits. We even produce the grinding equipment necessary to get the best out of each bit!
The underground drilling environment is made safer t hanks to our Boltec, Cabletec and Scaletec rigs, all of which are helping increase the utilization of our Simba rigs. Continuous Continuous innovation ensures that Simba rigs stay ahead, with drill bit
In this book we describe our underground production production drilling products, their applications, and their specifications. We hope this will stimulate technical interchange between underground miners, managers and consultants, universities, universities, and our own sales and marketing organization, resulting in better communication and collaboration.
changers, laser rig alignment and positioning units adding
Above all, we wish to make it easier for our customers to
utilization, while computerized drill plans, strata logging and
select the right equipment for their par ticular application, for more efficient production and a safer environment, so that we continue to be the supplier of first choice.
onboard communications systems fine tune drilling quality. As a result, Simba rigs can be equipped to drill continuously through meal breaks and a nd shift changes, reporting every move move to the office!
Mikael Ramström Product Line Manager Underground Drilling Equipment Atlas Copco Rock Drills AB
[email protected]
2
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Percussive rock dril drilliling ng A century of drilling and development
s
Over the last 100 years or so there have been rapid and impressive increases in efficiency and productivity in tophammer drilling. Technical development started from hitting a steel manually by a sledgehammer, through pneumatic handheld drills and rig-mounted multiple drills, to today’s highfrequency hydraulic drills with optional automatic control utilizing state-of-the-art technology to achieve top efficiency.
Principles
5200 m/s
+ –
2 x piston length
Figure 1: Stress level in shock wave.
In percussive tophammer dril ling, energy is transmitted from the rock drill via the shank adapter, drill steel and drill bit to the rock, where it is used for crushing.
A pneumatic or hydraulic rock drill generates the energy required to break the rock. A pressure is applied on drive
area a or b (in Figure 2), which drives the impact piston forwards and backwards.
The impact piston of a hydraulic rock drill strikes the shank adapter typically 50-60 times per second, a frequency of 50-60 Hz, although there are examples of rock drills with much higher frequen-
cy like the COP 3038, which operates at 102 Hz. The entire system of rock drill, drill steel, bit, and rock contact must har monize for maximum drilling economy
Stress waves Theoretically, the stress wave has a rectangular shape, and a length of twice that of the piston. The stress amplitude depends on the speed of the piston at the moment of impact, and on t he relation-
ship between the cross-sectional area of the piston and that of the drill steel. It takes about 0.004 second for a stress
Figure 2: Principle of tophammer drilling.
machine housing impact piston
drive area a
shank adapter
damping piston
drive area b
drill rod coupling sleeve
drill bit rock
flushing hole rotation splines
PRODUCTION DRILLING IN UNDERGROUND MINING
3
TALKING TECHNICALL TECHNIC ALLYY
wave amplitude, is obtained with the long slender piston working at high pressure.
Piston 1 – 0,8 MPa
Efficiency and losses Piston 2 – 12 MPa
The wave loses some 5-7% of its energy for every additional coupling, as it travels along the drill string. This loss is partly due to the difference in cross-sectional cross-sectio nal area between the rod and coupling sleeve, and partly due to
Piston 3 – 20 MPa
imperfect contact between the rod faces.
The poorer the contact, the greater the energy loss. When the shock wave reaches the bit, the buttons are forced against the rock, thereby crushing it. The efficiency at the
bit never reaches 100%, because some of the energy is reflected as recoils or 3
reflecting waves (see Figure 4). The recoils can be of tensile or compressivee type. pressiv t ype. With a sharp bit, or when there gen-
2 1
erally is a shock wave with a too high energy content, or when there is poor
Shock-wave amplitude
rock contact, we get tensile wave reflections.
The poorer the contact between the bit and the rock, the less is the bit
Figure 3: Stress levels generated by different pistons of same weight.
wave to reach the rock using a 20 m long drill steel.
The total stresses that the wave contains are indicated in Figure 1. To To calculate the output power obtained s
Reflecting wave
+ –
Primary wave
Figure 4: Nature of drill string ‘recoil’ or reflecting wave.
from a rock drill, the wave energy content is multiplied by the impact frequency of the piston, and is usually stated in kilowatts (kW). Two rock drills having the same nomina l power rating might have quite different properties. Rock drill design engineers
seek to find the best combinations of various parameters, such as the piston geometry, the impact rate and the frequency for the application in mind.
4
The shock waves waves that are a re generated by hydraulic and pneumatic rock drills are significantly different in shape. Drill rods used with hydraulic rock drills will normally show substantially longer service life, compared with pneumatic rock drills, because of the higher peak stress levell obtained leve obtai ned with the t he latter’s piston. The reason is the larger cross-section needed on the impact piston when oper-
ating at the lower pressures (6-8 bar) of pneumatic systems compared to the 150-250 150250 bar of hydraulic systems. The more slender the piston shape, the lower the stress level (see Figure 3). In addition, a higher impact pressure,
efficiency.
With a worn bit, or when we have a shock wave with too low energy content, we get compression wave wave recoils. Both recoil types cause damage to the drill steel and rock drill, but the damage can be reduced with an efficient damper arrangement (see Figure 11, page 7).
Percussion pressure It is only when drilling in sufficiently hard rock that the maximum achievable
energy per blow can be utilized. In soft rock, the percussion pressure, and thus the energy per p er blow, blow, will have to be lowered to reduce the recoils.
a longer stroke length, and less piston weight give a higher impact velocity and a higher drill steel stress. Another
To get the t he longest possible service life from shank adapters and a nd rods, it is important to ensure that the working
consideration is that, for a ny given per-
pressure (and impact energy) is matched
cussion pressure, the stress in the drill
to the rock conditions and the drill
steel will be higher with reduced crosssection of the drill rods.
string at all times (see Figure 5).
Figure 3 compares the stress level generated by three different pistons having the same weight, but different shapes and working at different pressures. The lowest stress, or shock
Feed force Drill feed maintains the drill bit in close close contact with the rock to get benefit from the shock waves. However, the bit must
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Percussion pressure
Soft rock
Hard rock
Figure 5: Percussion pressure is lowered in softer rock to reduce reflected energy.
Feeding
Low percussion pressure
High percussion pressure
Figure 8: Working relationship between bit diameter (x-axis) and sp eed of rotation for a given drill. Figure 6: Feed force must be m atch- ed to percussion pressure.
If the impact pressure (and power) is
• specific gravity gravity and particle particle size –
increased, the required feed force will
the larger or heavier the particles, the higher the flushing speed that is
be increased (see Figure 6).
Rotation
still be able to rotate. The feed force must always always be matched to t o the percussion pressure. To do this, the feed force is increased
until the joints are a re well tightened (but still easy to loosen) at a good penetration rate. Further increase will cause
shaped particles.
drill bit to a suitable new position for the next blow, giving the bit a correct index-
A rule-of-thumb is that the flushing
frequency and reduced bit diameter (see Figures 7 and 8). If the actual rotation is not smooth for a fixed fi xed impact frequency fre quency,, shank adapter life will be reduced.
When using insert bits instead of button bits, the recommended rotation rate is 10-20% higher.
Flushing
deviation and shorter service life of the
Drill cuttings are removed from the hole bottom to the surface sur face by water flushing or air blowing blowing,, or a combination (water (water
drill steel due to problems with uncoupling the rods from a high tightening
mist). As the pow power er output from rock drills increases, giving increased pen-
torque. In the case of poor feed, the penetrapenetr a-
etration rate, efficient flushing f lushing becomes
tion rate will drop, and probably the rotation torque will not be high h igh enough to tighten the couplings, which will run ‘open’. The service life of the drill steel will thus be shortened.
require more speed than flaky fla ky,, leaf
The purpose of rotation is to turn the ation. Using button bits, the periphery is turned about 10 mm between blows. Consequently, Consequentl y, the rotation rate rat e needs to be increased using higher impact
Figure 7: Relationship between impact frequency and drill bit rotation.
required; • particle shape – sp spherical herical particles particles
more important. The flushing f lushing capacity capacity must be increased with larger bits and larger difference between the bit and rod size diameters
The required flushing speed will depend on:
PRODUCTION DRILLING IN UNDERGROUND MINING
speed in the hole should be a minimum
of 0.5 m/s for water flushing and 10 m/s for air f lushing (or (or water mist). The
flushing medium is normally water for underground drilling.
Setting parameters The drilling dril ling parameters for percussion pressure, feed force, and rotation must harmonize, in order to optimize drilling economy.
In practice, the driller sets the percussionn pressure to get an acceptable, cussio but not excessive penetration rate, and then sets the rotational speed with regard to the percussive frequency and bit diameter.
When drilling starts, the feed is adjusted to get even and smooth rotation. If this is not achieved, the percussionn and feed pressure can be percussio progressively reduced. Smooth and even
rotation will result in good penetration and long component service lives. Lost energy, representing low efficiency, will result in excess heat generation.
5
TALKING TECHNICALL TECHNIC ALLYY
Soft/Medium hard rock
Hard rock
10,000 psi 70 MPa
Very hard rock
30,000 psi
50,000 psi
210 MPa
350 MPa
70,000 psi 480 MPa
Figure 9: A range of rock types and hardnesses, which can be tackled by rock drills successfully.
The temperature of the adapter sleeve can be checked to ensure that the drilling parameters are correctly set. Immediately after drilling, the temperature should be approximately 45 degrees C when drilling with water flushing and about 60 degrees C for air flushing. Atlas Copco provides
a temperature gauge: part number P/N 9850 8715 00. Loose couplings will cause drilling problems, but they can be
Additional factors in longhole drilling
tightened during drilling by increasing the friction of the bit against the hole
There are some special parameters that
bottom. This can be done by increasing
the feed, increasing or decreasing the
drilling. Water entry: The entry of water
rotation rate, or by changing the bit.
into a rock drill and the hydraulic
have to be borne in mind for longhole
Figure 10: Comparison of properties for the two stroke lengths in the COP 2550UX rock drill.
Impact Impact Power (kW) Pressure (bar)
26
260
25
250
24
240
23
230
22
220
21
210
20
200
19
190
Impact Energy (J)
Percussion Data COP 2550UX 550
4
3 h t g n e l e k o r t S
6
Stroke 3
y g e r n r e E u s
Feed Force
500
r e w o P
8
Stroke length 2
450
s r e P
5
E
400 18
E =
E
180
P f
1 17
P= Impact power E= Impact energy f = Frequency
170
3 16
160
15
150
14
140
13
130
12
120
11
110
10
100
350
Stroke 2
300
Equal Impact Energy 250
2
38
40
7
45
50
A changed stroke length and impact pressure can maintain the impact energy but increse the frequency and the impact power.
200
54
Frequency (Hz)
The chart shows indata for impact pressure 180 bar with stroke length 3 (intersection 1). The frequency is read to 40 Hz (2), the impact power at this frequency is 16,8 kW (3) and the impact energy is 420 J (4). By changing to stroke length 2 and maintain the impact energy 420J (5) the impact pressure needs to be set to 238 bar (6). The frequency achieved is 53 Hz (7) and the new impact power is 22,2 kW (8).
6
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
two strokes. For soft rock or small bits a lower impact energy and a higher frequency is preferable because each blow
2 1
Constant oil flow
1 8
contains enough impact energy to crush
the rock and, therefore, the penetration rate increases the higher the frequency. Stroke length 2 in Figure 10 is thus more
suitable because, for a certain (low) energy, it gives the highest frequency f requency..
4
3
5 “floating” position
7
6
Figure 11: 11: Hydraulic dou ble damper.
system may, may, especially especial ly when in comc ombination with drill cuttings, lead to premature wear and failure of rock
can be eased, even if the drill string is not stuck. With a hanging drill string, the extractor helps the percussio percussionn in
drill and hydraulic system components. components.
‘rattling loose’ the drill string.
Consequently there will be high running costs and downtime.
This risk can be limited by using a drill collar assembled on the shank adapter when drilling dri lling upwards. Worn out flushing seals must be changed immediately. The new COP 2550UX rock drill has extra seals to cope with high flushing pressure and prevent water ingress, especially in drilling up-
holes. Water Water from the ‘tell-tale’ ‘tell-ta le’ hole at the front of Atlas Copco drills gives a signal to the operator when the seals are worn out. Dirt entry: Dirt in combination
with water will cause heavy wear and reduce the service life of components. All Atlas Copco rock drills sold on
Adapting impact power to rock and bits The concept of impact power can be confusing, since a combination of high energy and low frequency can give equally large power as for low energy and high frequency. Two rock drills having the same nominal power rating might therefore have quite different properties.
A change between stroke lengths but at the same impact pressure does not normally require any change in feed force. It is therefore advisable to choose a rock drill with as much impact energy as needed to crush the rock, but not excessively high, and the frequency
set as high as possible to get the best penetration rate.
Obviously a rock drill cannot be tuned to deliver the ‘ideal’ shock wave energy to crush the rock throughout the drilling operation. The bit gets worn and
Hydraulic dual damper
Atlas Copco’s Copco’s COP 1838HE 1838HE drill dr ill is ing with a bit diameter 76-89 mm. The impact piston has two different stroke
which may lead to problems with uncoupling the threads and high wear on the driver in the rock drill. With an extractor device, uncoupling the tubes
maximum impact energy.
higher penetration rate.
especially developed for long hole drill-
and TDS 87. The high contact pressure at the bit leads to high rot ation torques,
rock combination is much less than the
so the ideal energy amount increases,
mating surfaces, which means that the lubrication air pressure, generally 2-3 bar, is applied to the mating surfaces
string may cause problems, especially when drilling long holes downwards with tube drill strings such as TDS 76
limited. If not, stroke 2 can be used. This means also that a rock drill does not necessarily have to be run at its rated impact power to perform optimally. The impact energy required for the actual bit bit--
Simplified, impact energy requirement derives from rock properties and the hole dimension. Increased frequency,, and the power, then gives a frequency
underground drill rigs have pressurized
and cavities for the tie rods, preventing dirt entry. Heavy drill strings: A heavy drill
For hard rock or large bits high impact energy is required to crush the rock. With the COP 2550UX, both strokes 2 and 3 give high impact energies if the pressure is raised. Stroke length 3 has a lower frequency and is thus most suitable if the input power is
lengths, giving ‘two rock dr ills in one’ one’..
COP 2550UX is a new 25 kW rock drill for T51 drill steel with a bit diameter 76–115 mm. It also has two stroke positions, and is supplied with a powerful hydraulic extractor to save time and drill steel. Figure 10 shows the impact power as
a function of the impact rate for stroke lengths 2 and 3. The corresponding impact pressure at each graph point is shown in black. There is also a compari-
son of the same impact energy for the
PRODUCTION DRILLING IN UNDERGROUND MINING
but it’s possible to set the parameters to a good compromise.
Atlas Copco’s more recently developed hydraulic rock drills like COP 1838-series and COP 4050MUX have a dual-damping system. This is an effective device for giving a good ‘suspension’ of the drill string just as it absorbs compression recoil energy.
Older models like COP 1238ME havee a hydraulic single-stage damping hav system, which is less effective and lacks the energy-absorbing energy-absorbing feature, but still is better than drilling without damper.
The dual-damping system provides good contact between the bit and rock to increase penetration rate, and give a good tightening torque on 7
TALKING TECHNICALL TECHNIC ALLYY
impact piston (on the right) has hit the
12a
shank adapter and started a return stroke
away from it. The extractor piston has been hit by the shank adapter through the collar on the middle of the shank. The extractor piston ‘bounces’ on the hydraulic fluid (red) and hits the shank adapter again, but in the right direction to free a stuck steel, as indicated by the ‘feed force’ arrow.
Feed system In order to obtain controlled rotation torque for good, but not excessive, cou-
pling tightening, Atlas Copco uses its RPCF (Rotation Pressure Controlled
12b
Feed) feature in the drill control system.
If the rotation pressure (and torque) increases, the feed force is reduced, and
vice-versa, vice-v ersa, in a controlled way. If the rotation pressure gets excessively excessively high,
the feed is reversed (anti-jamming) in order not to get stuck. The drilling equipment performs best
when the feed is applied in a controlled and smooth way. A hydraulic cylinder feed gives a smoother operation than a chain driven feed.
Set parameters Figures 12a and 12b: Operation of a hydraulic extractor.
coupling threads. It also increases shank adapter and drill steel service lives.
When drilling upwards, the damper pressure will increase due to the
Referring to Figure 11, the basic reflex damper system consists of a
increased weight weight of the drill dril l string, and the opposite when drilling downwards.
damping piston (1), accumulator (2) and
Atlas Copco longhole drill rigs have a control system feature called DPCI (Damper Pressure Controlled Impact), which senses the damper pressure and
shank adapter (3). The impact piston is (4). When the reflected shock wave knocks the damper piston backwards (to
the right), the pressure rapidly rises in the chamber (5) as the check valve (6) is closed. This forces oil in chamber (5) to
maintains set impact pressures depending on the damper pressure.
Hydraulic extractor
by means of heat. At the same time, the
A major contributor to overall productivity and economy in longhole drilling is Atlas Copco’s device, the hydraulic extractor, which is optional on all Atlas
back to establishing contact again with the shank adapter (3).
A good way of checking that a correct feed force is applied is to monitor the damper pressure. When drilling horizontally it should be kept constant at a certain level depending on the rock drill model, the drill steel and bit.
8
changes can be assessed properly. properly.
Atlas Copco gives thorough general instructions on how to set the initial rock drill parameters at ev every ery start up of a new rig. By using the Atlas Copco-develo Copco-developed ped drilling simulation program Diarot, one
can predict drilling performance and give settings recommenda recommendations tions in order
to optimize drilling for the conditions. Again, all final settings sett ings must take place on site in any case.
be released to the oil reservoir (7) over the edge (8). This absorbs the energy
accumulator (2) is charged, to provide a fast movement of the damper piston
All final settings must take place at the face, where the effect of parameter
Copco hydraulic rock drills for longhole drilling. The extractor is comparable to a sliding hammer and it eliminates jamming in the hole, but can also be used to ease
Hydraulic rock drill suitability See the separate machine specifications in the final section of this reference edi-
tion as regards the suitable conditions for each drill model.
Fredrik Öberg
loosening of joints during longhole drilling drilli ng downwards. downwards. In Figure 12a, the PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALLY
In-The-Hole (ITH) vs tophammer drilling in underground mining Pneumatic and hydraulic Until the late 1960s, pneumatic tophammer drilling, employing around 6 bar pressure, was the logical choice for the full variety of holes needed in an underground mine. Raiseborers employing rotary drilling were introduced to supercede conventional manual stoper drilling using ladders and timber platforms, or the Alimak method. By boosting mine air pressure up from 6-7 6 -7 bar to 10-11 10-11 bar, down the hole (DTH) hammer drilling became feasible, and was used mainly for holes requiring high accuracy, such as for drainage, cables and long hole winzes and raises. For production drilling in open stoping, the down the hole drill became popular, especially in Canada. It could be used for drilling in all directions, including up holes, and the term DTH, as used in surface applications, was dropped in favour of the more descriptive ITH for underground work. Pneumatic tophammer drills were progressively replaced by more-efficient hydraulic rock drills, and the pneumatic pressure was increased in stages up to 25-28 bar for the new generation of ITH hammers.
Figure 1: Simba M6 C production drill rig with IT ITH. H. Figure 2: Influence of bedding and foliation on drilling.
In case α is greater than 15° the hole deflects perpendicula perpendicularly rly to foliation (bedding).
Tophammer drilling The main drawback with tophammer drilling is the in-hole deviation that limits the practical hole length. As the magnitude of deviation is exponential to the hole length, tophammer holes are normally restricted to around 30 m. Penetrating structured struct ured rock with strong foliation and bedding properties can cause deviations of up to 5-10% (see Figure 2).
As a result, many mines avoid drilling holes deeper than 20 m, unless guide
rods are added directly behind the bit, or drill tubes are used. In these cases, the deviation deviation can be expected to decrease PRODUCTION DRILLING IN UNDERGROUND MINING
9
TALKING TECHNICALLY
to 3-5%. 3-5%. Figure 3 illustrates the t he problem
with tophammer tophammer drilling patterns in a typical sub level stoping application. The problem is, in fact, three-dimension three-di mensional, al, and can produce excessive excessive burden and toe spa-
Typical influence of bedding on long hole tophammer drilling in sublevel open stoping, max hole length 30 m
cing, resulting in misfires or poor fragmentation.
ITH drilling The penetration rate of ITH rock drills is almost proportional to t he applied air pressure, so an increase to 28 bar will almost treble the net penetration achieved using 10.5 bar. As water mist drilling is necessary underground for dust suppression, suppression, there is a net penetration loss of some 20% compared compared to dr y drilling on the surface.
Positive Positiv e features of ITH normally the in-hole • Straight holes – normally deviation is maintained within +/-0.5% (max +/-1%). This means that hole lengths up to 75 m are
Ore boundaries Designed hole direction Actual hole direction Critical area for fragmentation
commonly used in large mines, such
Figure 3: Typical influence of bedding on long hole tophammer drilling in sublevel open stoping, maximum hole length 30 m.
2.0
6.50
2.50
15.00 m
15.00 m 50°
1.50
3.70
45° 3.70
1.500
chutes, and better overall economy of materials handling. The usage of ITH drilling challenges the mine planner
Undercut drilling using tophammer at El Soldado, Chile ll l
l
l
ll
l
to a new dimension of stope design and geometry. As actual versus de-
ll
30°
C 3.5
signed hole pattern and location coin-
3.5
E 50 to 75 m
B
A
50 to 75 m
t f a h S
C O R T E
B
45.0°
used for establishing the trough t rough unC´
45.0°
Section
Plan drilling level
Production drilling pattern using ITH at El Soldado, Chile
Figure 4: Tophammer and IT ITH H drilling patterns.
10
cides well, the ore/waste ratio can be better controlled. Figure 4 shows the drill pattern used at El Soldado, where 64 mm tophammer drilling is
A´
E
as El Soldado and Mount Isa, with negligible hole deviation. Such hole accuracy can result in substantial savings in the development of drilling drifts, as the sublevels can be spaced further apart. A prerequisite is that the orebodies have adequate size and regular ore/waste boundaries. Less hole deviation deviation means controlled fragmentation of blasted material, resulting in less drawpoint hang-ups, less secondary breaking, less blockages of ore passes and
dercuts, combined with 165 mm ITH drilling for downhole bench drilling
from the sub level above. In order to get best usage of the larger holes, the layout of this level resembles a surface bench used at quarries and open pits. PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALLY
devell• Longhole raises can be better deve oped, with higher precision. fractured ured • Less risk of getting stuck in fract and faulted rock conditions. Low noise level noise level at the worksite, worksite, as the •
hammer is working inside the hole,
•
close to the bit. Simplicity of operation, service and
maintenance means that high availability of equipment can be expected.
Nevertheless, Nev ertheless, to obtain high utilization, a certain scope of mining is required. A single rig has a capacity of about 60,000-80,000 drilled m/year,
depending on conditions, assuming 2 or 3 shifts/day shifts/day,, so yield per r ig can easily exceed exceed 1 million mi llion m3, provided
that drill sites are available and this
Conventional tophammer T45/51
order of production is required.
As the hammer is always in direct contact with the bit, no percussive energy is lost in joints. Hence, the net penetration rate does not drop as the hole gets deeper. For tophammer drilling, around 5 % of the percussive energy is lost at every additional rod joint.
Drawbacks Drawbac ks with ITH I TH • 6-25 bar compressed air pipes have to be installed on the drilling level, to provide the required pressure boost.
Crown pillar
4.5 m 8-15 m Typical cable cab le bolting ∅ 51 mm drill bit
Production drilling ∅ 74 mm drill bit
Drawpoint level
Figure 6: Influence of drilling methods on d eviation.
• High air volume consumption • ITH drills larger larger holes holes of 90-254 mm.
applications, applicatio ns, due to the large amount
The normal range is i s 110 -1 -178 78 mm, compared with tophammers at 51-102 mm. As more explosives are used per metre of hole, the cracks after detonation propagate further away from the hole. As a rule of thumb, for every additional 25 mm of hole diameter, the cracks migrate one more metre. As a result, drawpoint brows and sidewalls in pillars
the working site. Installed rock reinforcementt might also be subjected to forcemen damage.
Summary There is no simple answer as to which drilling method is preferable. There are advantages and disadvantages with both
methods. One governing issue is how
might be overblasted and cracked. • Irregu Irregular, lar, narrow orebodies cannot
much in-hole in-hole deviation can be accepted ac cepted for successful blasting results.
take advantage of the longer and
Regarding hole deviation related to misalignment and collaring errors, new Atlas Copco drill rigs for both
larger diameter holes. • As tophammer drilling constitutes
the only alternative alter native choice for devedevelopment of drifts, crosscuts, ramps, rock reinforcement and miscellaneous infrastructure, an additional drilling method is being introduced with ITH. Figure 5 shows a topham-
mer Simba used for both cable bolts Figure 5: Tophammer Simba is used for both cable bolts and production drilling at Zinkgruvan, Sweden.
of wet drill cuttings descending to
tophammer and ITH drilling are robus robustly tly
designed and equipped to keep deviation problems to a minimum. Figure 6 shows differences in hole deviation with the different methods.
Hans Fernberg
and production holes. • Uphole dril drilling ling is is avoided avoided as much as possible, except in sublevel caving
PRODUCTION DRILLING IN UNDERGROUND MINING
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Simba L6 C drilling upholes.
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PRODUCTION DRILLING IN UNDERGROUND MINING
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Drilllling Dri ing long straight s traight holes Avoiding hole deviation To achieve good fragmentation dud uring blasting, it is important that the drill holes follow the designed direction along their entire length. Two obvious causes of hole deviation, however however,, are poor hole alignment and imprecise collaring, although in principle these can be avoided by good working practice on the part of the drill rig operator. A third, and less easy factor to overcome is in-hole deviation, usually owing to the geological conditions of the rock mass being drilled. Consider, for example, a hole that is being drilled in rock comprised of a soft and hard layer separated along a plane that is not at right angles to the drilling direction. Depending on the angle of approach to the plane of separation, hole deviation will arise as a result of the bit either sliding along the harder material, or, alternatively, penetrating the softer material faster. Only if the rig operator knows at what depth this plane of separation lies, can he take appropriate action, such as reducing the percussion and feed pressure of the rock drill when passing from soft to hard or hard to soft rock.
Collaring misalignment Collaring offset
Planned hole
In-hole deviation
Incorrect depth
Figure 1: Various causes of hole deviation.
hole deviation are shown in Figure 1.
Drilling according to plan To achieve the required requi red fragmentation as indicated by the pre-calculated blasting results, it is a prerequisite that the
blast holes are drilled according to the drill plan. This means that the holes must be collared in exactly the right position, and then drilled in the correct
direction and to the exact depth indicated in the drill plan. Precision in collaring and hole align-
ment can be achieved with proper surveying veyin g and mark-ups of the drill pattern
grid, coupled with a drill angle indicator mounted on the drill feed, and a hole depth instrument.
It is also essential to have a good view of the collaring procedure from the operator’s cabin. Various causes of
Due to collar error
The most influential factor in achieving accurate drill holes is in-hole deviation during drilling, which is usually a result of the particular geological characteris-
tics of the rock mass, such as the grain size, and the degree of fracturing and foliation. The adverse effect of bedding
to be a tendency for the drill bit to penetrate the rock in a direction di rection that is parallel to the bedding beddi ng plane when the angle
of approach is less than 15 degrees. In contrast, drilling drilli ng through homogenous rock, such as isotropic granite with minor fracturing, results in little or no inhole deviation.
and foliation on in-hole deviation can be clearly seen in Figure 2 where the drill holes have tended to deviate in
Drill string bending
directions at right angles to the jointing
Aside from geological conditions of the
within the rock mass. It is also noticeable that the longer the drill holes, the more accentuated is the deviation. It is often claimed that the amount of deviation is proportional to the depth
rock mass, other perhaps less obvious
squared.
(Figure 3). During the drilling operation, the fric-
Experience shows that the approach angle of the drill dril l bit towards the bedding planes is crucial, and there appears
PRODUCTION DRILLING IN UNDERGROUND MINING
in-hole factors can have a marked inf luin-hole ence on hole deviation, such as hammer specifications and condition, and the bit
and drill string design and condition tion generated between the drill bit and the rock induces a torque in the 13
TALKING TECHNICALL TECHNIC ALLYY
condition, conditio n, particularly part icularly with respect to regrinding. From an accuracy point of view, a flat front bit or a drop centre (concave) front bit (Figure 5) results in a straighter stra ighter hole than a drill bit with a convex front.
It must also be remembered that t o obtain the best hole accuracy with all drill bits, they must be reground so that their faces are restored to their original
shape in terms of both the buttons and the steel, even if this is more time consuming than simply ‘polishing’ ‘polishing’ the but-
tons and not removing any of the steel g n i d d e b / n o i t a i l o f f o n o i t c e r i D
between the buttons. In this regard, dropcentre drill dril l bits are, once again, prefer-
able to their convex counterparts since the concave shape needs only to be reground such that the profile of the central buttons is restored to its original pat-
tern without adversely affecting hole straightness, even when the concave face
eventually eventu ally wears flat through normal operation. If the drill dri ll bit face is plane all the way out to its periphery, the bending moment in the drill string will be proportional to the product of the feed force and the hole diameter, while the lateral displacement of the drill string will be limited by the
diameters of the drill bit and the drill string. Thus, if the drill bit is correctly and frequently reground, the feed force
Figure 2: Hole deviation shown in a wall of varied, jointed rock types.
drill string stri ng above above a certain drill rotation rate. The larger the drill string diameter
it is now supported at two points along the hole. At three times the theoretical
and the greater the rotation rate, the
bending length, the drill string will once again buckle, and so on with increasing hole depth.
higher is the torque necessary, and thus feed force, to keep the drill string joints sufficiently well tightened.
At a particular part icular point along the hole, the drill string will buckle, so that rather than being straight in the hole it is supported by the hole wall close to the midpoint between rock drill and a nd the hole
bottom. For a COP 1838ME rock drill, with a drill string diameter of 38 mm and a feed force of 6,400 N at a percussive pressure of 200 bar, this bending length is approximately 11 m. In practice,
bending occurs at a somewhat shorter interval since the drill string is never perfectly straight at the commencement of drilling.
When the drill string has been extended to twice the theoretical bending length, it will buckle once more, so t hat
14
Assuming the same combination of drill string, impact force and rotation rate, rock drills with ‘floating dampers’, such as the COP 1800-series, COP 2550
and the COP 4050 rock drills require less feed force to keep the drill str ing jointss well joint wel l tight tightened ened tha thann those t hose rock drills incorporating ‘fixed dampers’, such as the COP 1032 and COP 1238 units. Those rock drills with an axial bearing between the drill string and the machine require the greatest feed force to maintain joint tightness.
will be directed to the periphery of the drill bit so that the whole cutting face is in contact with the base of the hole, even if the drill string buckles. With poor and infrequent i nfrequent regrinding, however, the drill bit may ‘wiggle’ on the hole-bottom owing owing to the uneven distribution of the feed force, and will sooner or later result in hole deviation.
Drill string considerations Other things being equal, the larger the diameter of the drill string, the straighter the drill hole that will be achieved, since
the drill string diameter has more of an influence on the bending length than the feed force (Figure 6). In addition, a larger diameter drill string increases the safety
margin against ‘wiggling’ (i.e. the ratio between the maximum bending moment
Drill bits and regrinding
of the drill string and the bending mo-
Also influencing inf luencing hole hole deviation is the geometry of the drill bit face and its
ment at which bending occurs) so that less careful regrinding can be tolerated before
‘wiggling’ sets in. This does not mean,
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
however, that larger string dia-meters should be deployed in preference to less careful grinding. Since drill tubes have larger diameters diameters than drill rods, they result in greater hole straightness.
A complete drill string of tubes is often necessary in downward production drilling underground in order to
Out-of-the-hole factors
Operator-related factors
In-hole fa factors
Set-up errors
Drilling parameters
Rock conditions
• Wrong set up position • Wrong set up angle
• Feed force • Rotation • Flushing
• Grain size • Fractures • Foliation
achieve sufficient flushing f lushing capacity. An attractive alternative is the adop-
tion of a guide tube connected to the drill bit, which, owing to its larger diameter, reduces the possible amplitude of
drill bit ‘wiggle’ compared with rods.
Importance of rotation
into the drill bit should be as long as
If a dril l string is buckled, then the
possible. Unlike a drill string comprised solely
buckled section may rotate, whereby the bit will work over all of the hole bottom. In this case, there should be no hole hole deviation, even even if the bit is only in contact with the rock at one or two points at the periphery.
transmitted via ‘shoulder impact’, stress
waves wav es in a drill string incorporating a guide tube are transmitted down the rods
to the guide tube via ‘bottom impact’. Thus the guide tube does not suffer from premature female thread failure. Even though a guide tube will always result in a marginal decrease in drilling
rate (depending only on the cross sectional area increase relative to the rods in the rest of the drill string, rather than the drill tube length), the improved hole
straightness achieved is normally of greater value to the mining engineer. Another way to minimize minimi ze ‘wiggling’ ‘wiggling’
is to use Retrac bits (Figures 7 and 8). Characterized by a bit skirt with the same outer diameter as the bit head, in in
• Hammer parameters and condition • Bit and drill string design condition • Cradle guides • Drill steel support
Figure 3: The drill rig rig operator can eliminate, in principle, many of the factors factors influencing hole deviation. Less easy to overcome, however, are the geological conditions of the rock mass being drilled and equipment-related influences.
Also, as the possible angle of ‘wiggling’ decreases with increasing length of the guide tube, the guide tube incorporated
of tubes, where the stress waves are
Equipment re related factors
It is more li kely kely,, however, however, that the buckled section will not rotate, which means that the drill string will be sub jected to rotational rotat ional bending. bendi ng. The bending moment moment in the drill dril l string corre-
than the nominal bending stress. For example, the rotational bending stress in a drill string incorporating 38 mm diameter rods with a feed force of 6,400 N and a hole diameter of 89 mm is approximately 15 MPa, equivalent to around 5% of the stress wave amplitude
generated by the piston. In this case, therefore, either the impact velocity of the piston must be reduced so that the stress wave amplitude is 5% smaller, or
the hole may be drilled at a 5% higher impact velocity (corresponding to 5% higher frequency, around 15% higher
sponds to the maximum nominal bend-
impact power and, hence, a 15% higher
ing stress in the drill string, which is measured some distance from the
rate of drilling) provided that the drill
threaded ends of a rod. However, stress-
concentration factors in areas close to the threaded ends result in stresses in
string length is less than the theoretical t heoretical bending length.
In practice, the operator cannot be
these regions that are significantly higher
expected to reduce the percussi percussion on pressure simply because the pre-determined
Figure 4: Button bit with flat front.
Figure 5: Button bit with drop centre front.
effect a very short guide tube with maximum possible diameter, Retrac bits have
been developed primarily to improve retraction of the drill string in difficult rock conditions where the tendency for jamming frequen frequently tly occurs. Debris from
the hole is flushed through slots machined along the bit, and the rear end of the skirt has a cutting edge between every slot.
Since the Retrac bit cannot ‘wiggle’ ‘wiggle’ as much as a standard bit with a skirt that is significantly smaller than the bit
head, hole straightness is, once again, improved.
However, the use of long guide tubes will normally result in straighter holes than those drilled using Retrac bits. PRODUCTION DRILLING IN UNDERGROUND MINING
15
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O D D R E E S P T 3 8
Long hole precision drilling In-hole deviation as function of hole length
R O D E E D P S T 4 5
(Derived from investigations at LKAB, Kiruna)
Deviation 1.50 m
o d d e r u i d G T 4 5
1.00 m
u b e 6 4 t S T D
0.50 m
15
20
25
30
35
40 m Hole depth
Drill Strings relating to Diagram T38 SPEEDROD® T38 SPEEDROD®/ Standard bit T45 SPEEDROD®/T45 GUIDE ROD/ (old design)/Retrac Bit TDS 64 tube/TDS 64 tube/Guide Bit
Figure 6: Larger diameter drill strings result in less In-hole deviation as a function of hole d epth.
bending length of the drill string has been exceeded. On the contrary, the operator requires increased increase d percussion pressure to counteract the decreasing
percussion pressure according to the
exceeds the theoretical bending length,
particular circumstances, so the drill rig
the percussion pressure must be regulated so that the drill string is not sub jecte jec tedd to t o rota r otation tional al bend bending ing at tho those se
drilling rate owing to increasing bit wear. Therefore,, the operator must determine Therefore determ ine
hole depth does not exceed the bending
Figure 7: Bit with Retrac skirt. Drop centre front and ballistic buttons.
Figure 8: Bit with Retrac skirt. Drop centre front and spherical buttons.
may be operated at higher percussion pressures for those holes where the length. Alternatively, if the hole depth
points where it is buckled. Drill string stri ng rotation also gives gives rise to another complicating factor with respect
to hole straightness in terms of the phenomenon of ‘whirling’. Similar to the ‘critical rotation rate’ for rotating machines, ‘whirling’ gives rise to a smaller bending length than for a drill string that is not rotating, rotating, and mathematically can be shown to be approximately
80% of theoretical bending length of a stationary drill string.
Non-vertical holes The bending length referred to thus far relates only to vertical holes. For slanted holes, the weight of the drill string gives
rise to bending, so that the drill dril l string is never straight, and, as with rotational influences, results in a shortening of the
theoretical bending length as the hole becomes more horizontal. In benching and production drilling drill ing underground, the holes are almost vertical however, and the effect of dr ill hole angle is normally negligible negligible in these applications.
16
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Other factors
•
Although relatively uncommon, another an other
phenomenon is worth mentioning with respect to in-hole deviation.
During drilling, dril ling, the piston subjects the drill string to a pulsed axial stress, the periodic load of which may theoretically initiate resonance vibration, resulting in plastic deformation of the drill string close to the joints. This phenomenon is very rare, how ever, owing to the fact that the boundary condition between the bit and the t he rock is never constant. Also, as soon as the drill string length is greater than the theoretical bending length, it will
straighter holes. • For tophammer dril drilling, ling, Atlas Copco
provides TDS tubes that can be added behind the drill d rill bit to improve
the flushing and reduce the risk of the drill string becoming stuck. Even en more accurate than tophammer • Ev
drilling are ITH, COPROD and rotary drilling, all of which result in
less deviation than with tophammer drills. •
inhibiting resonance vibration.
Less deviation deviation can be achieved achieved through a combination of reduced feed force and increased rotational speed.
be supported by the hole wall at one or
more points along its length, thereby
A stiff stiff drill string, string, and small small clearclearance between the hole and the dril l string components, will result in
•
Shorter holes allow the rig operator to better control the extent of hole deviation.
Remedies From a practical point of view, there are
various ways and means to minimize hole deviation owing to the factors outlined above above::
Summary Clearly it is impossib i mpossible le to completely eliminate hole deviation, but with the right
Figure 9: Bit with standard skirt and drop centre front.
this equipment in the optimum ma nner, the drill rig operator can influence hole deviation in a positive way.
choice of equipment and by utilizing
Patrik Ericsson
140 exc exciting iting pages all about: Mining methods in underground mining Get your own copy at www.miningandconstruction.com
PRODUCTION DRILLING IN UNDERGROUND MINING
17
TALKING TECHNICALL TECHNIC ALLYY
Simba M4 C drilling upholes.
18
PRODUCTION DRILLING IN UNDERGROUND MINING
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Automa Au tomated ted longho longhole le drilling drilling Redefining drilling standards Since the 1990s, Atlas Copco has been researching in novative ways of applying the rapid advances in computer technology to the specific needs of the mining and construction industries. The result is a generation of fully computerized drill rigs with much improved productivity, accuracy and serviceability. Designed with precision drilling, high productivity and swift availability in mind, the M and L ranges of Simba production drill rigs are equipped with the Atlas Copco Rig Control System (RCS), which is flexible and easily expandable. Significantly, the technology provides for varying degrees of rig automation and, ulti mately mately,, the possibility of fully automated and remotely monitored drilling. These drill rigs are of modularized design in both hardware and software, so their functionality is upgradeable step by step. Options such as Advanced Boom Control (ABC) Regular, ABC Total, Drill Plan Handling, Full Drill Data Handling (FDDH) and communication products are available to facilitate quality drilling. Atlas Copco has applied the same new automation technology for all drilling equipment such as Boomer drill rigs, Boltec rock bolting rigs, raise borers, the Cabletec cable bolting rig, the Scaletec scaling rig and ROC surface crawler rigs as well as underground loaders and trucks.
Rig Control System
The RCS-based production drilling rigs provide excellent operator's environment and improved drilling performance.
and electric influences. For production drilling rigs, the flexibility of the system
is highly utilized, and can be adapted and configured for all different types of applications. Customers can start at a low level of automation and, as their requirements change, can upgrade the
ogy,, has facilitated a quantum leap forogy
hydraulic valves instead of, or in con junction with, conventional hydraulic valves. The system is common on small and medium size Simba drill rigs.
functions. New functionality can be ad-
The RCS succeeded the Electrical
ded, without major rebuilding of the
Control System (ECS) in 2001 20 01,, when the latter became obsol obsolete. ete. RCS is intended for all kinds of automation in both basic and more advanced rigs. All Atlas Copco
rigs.
The current generation of drill rigs is designed for high productivity productivity,, accurate drilling, and a comfortable working environment for the operator.
RCS, which is a CAN-bus based system
using standard PC-computer technol-
The EDS electrical direct direc t control sysystem is an extension of the DCS control system, utilizing electrically controlled
Evolution of RCS
computerized rigs are equipped with RCS technology, which activates hydra-
ulic valves around the rig by an electrical signal from a PC rather than a switch or a lever on the operator's panel. Not only does this provide for advanced
ward with respect to logging capabili-
The Atlas Copco direct di rect control system
ties, serviceability and drilling accuracy
DCS is designed for basic basic drill rigs. DCS provides the operator with basic manual functionality,, such as manual boom pofunctionality
automation, proportional-type valve control, and incorporation of timers
sitioning, and manual drilling and rod handling. Although common on small Boomer drill rigs, the system is only available for the Simba 157 and Simba
trol, but it also allow al lowss the system to be
of drill rigs. CAN-bus systems systems use a single cable that interconnects a series of electronic components and al lowing
them to communicate with each other. The electronic modules are all a ll developed developed
solely for the rigs, and are ruggedized and protected from external magnetic
1257 production drilling rigs.
PRODUCTION DRILLING IN UNDERGROUND MINING
and parameter-based rock drilling conupgraded by installing new software at the worksite.
The simplicity of the system means that the driller does not have to be an 19
TALKING TECHNICALL TECHNIC ALLYY
Advantages
Disadvantages
DCS - Basic and robust
- Automation not possible - Line-of-sight remote control not possible
EDS - Basic and robust - Remote control panel - line of sight (LOS)
- Automation not possible - Less control functions for the drilling process
RCS - Full automation possible - Designed for built-in optional functionality - Can be upgraded in the field - Easy to maintain and adjust - Simple hydraulic and electrical system - Low maintenance cost - Easy to operate, with good man-machine interface - Less hose metres
- Depending on automation level the RCS may require a more extensive training programme
electrical engineer or an IT technician to operate, maintain mainta in or even upgrade a rig, yet still benefits from electronic and computer technology in increasing productivity and decreasing drilling costs.
Levels of automation With the RCS platform established, Atlas Copco has been able to engineer a wide variety of new automated functions for all of its RCS drill rigs ai med at lowering costs while increasing performance. The Simba M and L ranges of longhole drill rigs can be engineered to three different levels of automation: ABC Basic, ABC Regular and A BC Total. Total.
Included in all Simba RCS systems is a standard leve levell of automation, ABC
Points for and against various control options.
Basic. It consists of computer controlled boom and feed mov movement ement allowing accurate proportional movement. movement. Also included are: system monitoring and fault
Different levels of automation can be achieved for major d rill rig operations.
Ad v a n t a g e s Operation - Drill rig operation Man-machine interface
ABC Basic ABC Re gular ABC Total
length indication; basic logging; manual
Drill rig set up - Angle indication - Manual drill positioning - Automatic drill positioning - Automatic anchoring
n/a n/a
n/a
Rod handling - Manual rod handling system - Automatic rod handling system
n/a
Drill control - Hole length indication - Advanced drill control - Automatic drill control control (one-hole -auto) - Breakthrough automatic stop - Detection of worn out drill bit - Automatic fan drilling Logging functionality - Statistic logging - Maintenance logging - Drill quality logging - Measure While Drilling (MWD) System monitoring - Basic system monitoring - Rock drill surveillance system - Smart oil leakage shutdown access Rig communication and data exchange - Basic communication - Mine text massage system - Rig Remote Access (RRA) PC software - Ore Manager Equipped
20
diagnostics; data loading procedure; diagnostics; angle indication of feed position; hole drill unit positioning; positioning; and manual ma nual rod handling functions. There are two optional levels levels of ABC, namely Regular and Total. ABC Regular provides a medium level of automation, assisting the operator to accurately position, align and drill holes to the required depth, and to gather drilling drilli ng data for office analysis. For a Simba drill rig, ABC
Regular includes the ABC basic functionality plus: automatic rod handling handli ng and one-hole automatic drilling; drilli ng; boom
n/a n/a
n/a
n/a
drilling applications, a single operator can handle several rigs by just starting the autonomous autonomous dri lling of the com-
n/a
plete fan, fan , and then move move over to the next
as standard; Optional; n/a not available option
position feedback on operator’s display; logging of of drilled dri lled hole on PC-card which can be analyzed in the office, using the Ore Manager software. Options to ABC regular cover navigation to mine coordinate system; bit changer for tophammer
drill rigs; drill plan handling without full fan automation, but with automatic
positioning help. ABC Total enables a complete fan to be drilled automatically, converting conve rting the operator’s role to that of supervising the drill dril l rig. For production
drill rig. ABC Total for a Simba drill rig includes the ABC Regular functionality plus: automatic automatic fan drilli ng PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
from pre-selected drill plan; manual sequence and position teach-in to prepare for a fully automatically drilled fan;
automatic automa tic drilling, with manual positioning, automatic collaring and drill ing;
hole to hole move strategy; hole sequence programming; and computer guided positioning of boom and feed according to a pre-selected fan plan.
Drill rig operation Common to all al l automation levels levels is the
man-machine interface (MMI), which provides the operator with a simple si mple and logical graphical display of different functions for drilling control, such as the rig
The RPCF keeps the rod joints tight.
angle, current drilling parameters, r ig monitoring and fault detection.
The interface incorporates an Atlas Copco display and control panel unit mounted either in the cabin/canopy on the drill rig or on a remote trolley linked to the rig by a CAN-bus cable. Logical control makes the system easy to learn and, importantly importa ntly,, on-screen gauge
By simply holding down a button on the control lever lever the feed fee d will be position positioned ed in a fast and accurate way according to
positions defined on the drill plan. Further automation during rig setup can be achieved at the ABC Total level
with the automatic control control of the drill dri ll rig stingers and feed extension during
after the bit change and continue drilling to the required depth in one sequence.
Drill control Drilling to a precise hole-length is preferable to estimating the number of rods necessary to complete a hole. All three automation levels levels offer an indication of
displays eliminate the requirement for
anchoring and de-anchoring.
hydraulic hoses hoses to be linked l inked to the control panel or fed into the cabin.
Rod Handling System
hole length on the operator's graphical display panel, together with penetra-
Drill rig setup
To satisfy current drilling dr illing demands, a
tion rate. This latter information can be
A hole alignment accuracy of within
Rod Handling System (RHS) is included on Simba rigs. Depending on the se-
±0.1 degree is attainable with the Simba
lected drill string, the RHS allows the
particularly helpful in fine tuning the system or when testing different drill bits, and in giving a better bett er understand-
L and M rigs as electronic sensors provide graphical information on the operator's display regarding the drill's rotation angle and tilt angle, or fan inclination. The operator can configure the direction of rotation and locate the
operator to use either Speedrods or TDS tubes. TDS tubes improve hole straightness and flushing speed whilst minimizing the risk of the rods becoming stuck
zero points according to the mine’s drill plan. Collaring angles for each hole can be logged and stored if the drill-quality logging option is installed. Manual drill unit positioning positioning is fitted
in the hole. The RHS, which incorporates pre-programmed interlocks to prevent the rock drill and rod handling arms from hitting each other, can be
ing of what is actually happening in the hole.
Advanced rock drill control is now made possible using RCS, with the RCS platform providing smoother control of the drilling operation, minimizing drill
steel stress and impro i mproving ving the penetration rate. These benefits are a re achieved
operated manually with the position lever and buttons on the operator's panel.
through control algorithms incorporated into the system. To To maintain maximum
By automating the rod handling sequ-
penetration rates in different ground
as standard on all the Simba M and L
ence, which is included in ABC Regular
conditions, as well as in different drill-
drill rigs, whereby the drilling unit and
and ABC Total, Total, more drill dril l metres per
ing directions, the Rotation Pressure
feed extension extension are manually operated from the control panel. Proportionally controlled valves help the operator to quickly establish the required feed direction using the joysticks while pre-
shift can ca n consistently be achieved, most
Controlled Feed (RPCF) algorithm ad-
notablyy as a result of drilling during notabl
justs the drill dril l feed-pressure depending
breaks and shift changeovers. Operators
upon the measured rotation pressure. As
need only to key in the required depth
well as improving the penetration rate, this maximizes the life of the shank
programmed drill unit rotation end stops prevent accidental damage to any hoses. To speed up feed positioning in cases
ling of a hole, including automatic ad-
where the drill plan handling option is
pre-determined depth. To simplify drill bit changes in mid-hole, the system will
used there is an additional a dditional function called Automatic Angle Adjustment (AAA).
to initiate automatic collaring and dril-
dition of rods during the drilling sequence
and removal when drilling reaches the automatically feed rods into the hole
PRODUCTION DRILLING IN UNDERGROUND MINING
adapter, tubes/rods and drill bits by ensuring that the tube/rods joints are tightened with a constant torque throughout the whole length. length. This can also make rod
removal remov al easier as it is unlikely unli kely that the joints will be too tight. The Dampening
21
TALKING TECHNICALL TECHNIC ALLYY
Drill rig monitoring and diagnostics. Abnormal operational events recorded and stored in the Event Log (a, above), coupled with colour coding and descriptions of various cables and modules (b, above right) make fault finding (c, left) easier and faster.
at all automation levels with a basic system of monitoring monitoring vital rig parameters. Added protection to the drill can be provided by the rock drill lubrication
surveillance system, which terminates drilling if the rock drill lubrication air pressure and/or lubrication oil level and
pressure fall due to insufficient levels. Maintenance logging, a tool that draws the operator's attention to any uncharac-
teristic rig performance, is included in all levels of automation. Should key rig or rock drill operating parameters, such
as hydraulic oil temperature and level, percussion pressure or rotation pressure
exceed pre-set thresholds, the control function will identify the t he condition. In Pressure Control Impact (DPCI) algorithm, meanwhile, ensures that the drill
bit has good contact with the rock during high percussion periods by adjusting the percussion pressure according to the measured damping pressure. This
protects the rock drill from striking in open air or with full power in loose rock formations.
Finally, an anti-jamming function reverses the feed of the rock dri ll when excessive rotation pressure alerts the sy-
and, importantly, help help to minimize mi nimize hole deviations.
Several other automated drill functions can be incorporated to the Simba M and L rigs. Breakthrough Automatic Stop (ABC
Total and optional on ABC Regular) terminates drilling when the bit enters
Accidental loss of hydraulic oil can be detrimental, both in terms ter ms of cost for
bits can alert the operator when the drill
laring sequence for the hole. Automated drill control, on the other
need replacing. This is done by measuring the drilling sequence time.
can also be adjusted via the operator's display and control panel to suit varying rock conditions. Together, these features
result in much smoother collaring than can be achieved by manual drill dri ll control
22
lems owing to abuse, poor preven preventative tative maintenance or extreme drilling conditions.
tential costly loss of the drill string. Automatic detection of worn-out drill bits have exceeded preset values and
sequence that includes automatic collaring for the first rod. The collaring length
downloading and evaluating the data, downloading technicians can identify drilling prob-
a lower level, thereby preventing the po-
stem to a jam, and re-initiates the colhand, enables a hole hole to be drilled dri lled to a pre-determined depth in an a n automatic
these instances, rig and rock drill parameters will then be monitored and logged according to pre-set sampling sa mpling times. By
System monitoring and logging functionality As with all the other drilling operations, various levels of automation can be achieved for system monitoring, data
logging and downloading funct ions. The Simba M and L rigs are equipped
the mine and a nd the environment. Protection against such leakages is available through the smart smar t oil leakage shutdown
system, whereby the rig is shut down and the operator alerted with an onscreen message, if the control system detects a hydraulic oil leakage lea kage exceeding preset values. The Simba M and L rigs are also a lso equipped to log basic statistical data such as percussion hours, which can be down-
loaded onto a PC card by the operator. This tool is useful for service scheduling. Percussion hours for each individual
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Direct menus on the display allow required information to be found quic kly, including (bottom right clockwise) drilling parameters, angle indication, settings and drill plan.
rock drill used on the rig can also be logged separately. It is vital to accurately position holes
for the charging and blasting process and the drill quality logging function provides feedback feedback to the t he planning personnel on what was drilled, when and where. The Simba M and L r igs equipped with this tool can log hole angle and depth as well as position data, which can ca n be downloaded and used later to be compared with the actual drill plan.
standard for data exchange between rock excavation equipment and users’ computer systems. This International Rock Excavation Data Exchange Standard, or IREDES, is the common language in data exchange for mining and
tunnelling. Ore Manager, which is IREDES compatible, can also be used to analyze the outcome of a drilling sequence in order to optimize the sub-
Such standardized systems also mean
that end-users' costs can be kept to a minimum, since data transfer does not require more expensiv expensive, e, tailor-made in-
terfaces. Such cost considerations are particularly important for those companies and projects where automation could make the t he development development of smallscale operations more viable.
language for handling data, the mining industry can introduce new technology without being dependent upon one sup-
Original equipment manufacturers will also benefit from the development of standardized systems since valuable resources that would otherwise be tied up with interface customization could be freed up to concentrate on other
In order to facilitate use of different equipment from different producers in the
plier for intelligent mining automation
technology developments.
same organization, Atlas Copco, toge-
Indeed, third-party companies are enabled to provide add-on IREDES-
Rig communication
conformant parts to a range of customers at reasonable prices.
The communication link between the operator and the rig is a basic function
IREDES
ther with other major machine manufacturers, mining and construction companies companies and third party par ty suppliers, has established established a
sequent charge and blast sequences.
By defining one common format or
systems.
PRODUCTION DRILLING IN UNDERGROUND MINING
23
TALKING TECHNICALL TECHNIC ALLYY
and drilled holes; automatic angle ad justment to the closest hole in the drill plan; automatic adjustment of the hole start points, so they fit the working area
of the rig; basic navigation, navigation, manually entering the difference dif ference of the rig’s rig’s ideal position and the actual position, p osition, and/or
drill bit to point out marked reference points in the drift.
Drill Plan Adaptation (DPA) is an option to Drill Plan Handling that allows the operator to adjust the collaring lows point of the holes, keeping the hole bot-
toms in the same position. Using this option, the operator ca n avoid obstacles
and installations, and carry out collaring in cracked zones.
Mine Navigation Navigation (MN) is an option to drill plan handling that gives more possible navigation navigation methods. The drill dril l
that enables the operator to keep track
Another possible possible feature is the Re-
plans can be planned in the overall mine coordinate system. Full Drill Data Handling (FDDH) is alwayss included in A BC Total alway Total and a nd is an option to ABC Regular. FDDH includes
of the drill rig status or drill production
mote Desktop, which enables access to
data for maintenance and production
the drilling menus from a remote loca-
features such as: importing drill plans
monitoring purposes. Such a basic data
tion.
PC-card for transferring of drill plans and log information to and from the drill rig.
exchange function is included in all Simba rig control systems, whereby the
operators can download/upload data/ programmes from/to the rig control system using a PC-card. Very simple to use, the data is stored as .txt files, which can be accessed on any standard PC.
As an option, a mine text message system can be incorporated in the Simba M and L rigs allowing the operator to receive status and alarm a larm messages
transmitted from the drill dri ll rig over the mine's local radio network. These warning messages can be customized to a specific mine site and can include status, warning, error and alarm messages messages.. This function, or the similar data online
function, is essential when operating the drill rig in ABC Regular or ABC
Automation options All Simba drill rigs can be equipped with a series of major automation op-
that contain planned drill d rill holes; export-
ing quality logs that contain the drill result; graphical view of the planned and drilled holes; automatic angle ad justment to the closest hole in the drill plan; automatic adjustment of the hole start points, so they fit the working area
tions, such as: as: Measure While Dr illing,
of the rig; basic navigation, navigation, manually
Drill Plan Handling, Drill Plan Adap-
entering the difference dif ference of the rig’s rig’s ideal position and the actual position, p osition, and/or
tation, Mine Navigation, Navigation, Full Drill Data Handling, Rig Remote Access and Ore Manager. Measure While Drilling (MWD) function logs a number of parameters while drilling to provide quality input for analysiss of the rock properties. Hole depth, lysi penetration rate, damper pressure, feed
pressure, percussion pressure, rotation pressure and air/water pressure are recorded at intervals during drilling and the information, coupled with hole devi-
drill bit to point out marked reference points in the drift. FDDH also includes Measure While Drilling (MWD).
The Rig Remote Access (RRA) (RR A) option integrates the drill rig r ig to the customer’s site computer network. This en-
ables functionality such as work order handling, log data transfer t ransfer,, and remote troubleshooting. Using RRA, drill plans
can be uploaded to the drill rig, or log files downloaded to t he controller’s controller’s PC via a LAN/WLAN connection. Drill rig
Total automation modes as a s it allow al lowss the operator to respond to planned and un-
ation measurements, will indicate ore boundaries and assist in the charging
planned events on the rig, r ig, even when it
and blasting process. By optimizing the rock fragmentation in this way, costs for
status can be observed on-line using a standard web browser on a remote PC. Since machine monitoring is carried
the whole rock excavation process can
out through the mine site data network,
makes it possible for a single operator
be reduced. Drill Plan Handling (DPH) includes
there is no extra requirement for a machine specific data communication sysy-
to oversee the operation of multiple drill
features such as importing drill plans
rigs, while dedicated service request messages can be transmitted directly
stem or network. This reduces the lev level el
that contain planned drill d rill holes; export-
of cost and support necessary as local,
ing quality logs that contain the drill result; graphical view of the planned
on-site IT technicians can undertake rig on-site communication and network support.
is unattended. Used to its full potential, p otential, this system of one-way messaging from the rig to portable por table radios and computers
to the service technician.
24
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Further cost reductions re ductions are possible through: rationalization opportunities, even at smaller mine sites; cost-effective integration into existing network systems owing to standard communication protocols; more efficient production and rig maintenance planning owing to automated in formation exexchange between central office and the rig; and increased rig availability as a result of online expert trouble shooting
assistance from Atlas Copco, provided provided the mine data network has Internet connectivity or modem connection on site.
Ore Manager (OM) can generate a PC-compatible drill PC-compatible dril l plan, which has to be available when you should operate a drilll rig at the A BC Total dril Total level of auto-
mation. Ore Manager is a Windowsbased support software for the drilli ng operation in mining projects. OM runs on a regular office PC. It is primarily used for the creation, organization and a nd administration of drill dril l fans for Simba drill rigs equipped with the optional ABC Regular or ABC A BC Total Total functions. f unctions.
Rig Remote Access offers supervision or control of a drill rig.
and Mine 2-4D systems, and more are to come.
hydraulic, electronic, and software components introduced with the new generation rigs has made this possible possible.. Atlas
Drilling Drilli ng economy econo my
Copco strategy with RCS is to develop
The new generation of computerized drill rigs offers a very precise adapta-
a complete programme of electronically controlled drill rig products for the mi-
ning and construction businesses and to introduce automation options for all applications. applicatio ns. For operators, the learn-
OM also has functionalities for retr ieving and analysing quality logs and MWD data. OM provides a quick and easy way
tion of the drilling parameters to actual rock conditions, conditions, resulting in better drild rilling economy. Correct adjustment to the
to check a drill fan and to compare the
actual rock conditions ensures precise collaring, straight holes without deviation, and extended lifetime of drill string components. The driller’s experience counts, but RCS assists him to
perienced drillers alike a re capable of production drilling aft er a couple of
do a good job. Modern drilling in mines is associated with very precise requirements, in order to get the best fragmenfr agmen-
areas, such as navigation, and under-
tation and not to unnecessarily dilute
Conclusions
drilling result with the planned fan. The result is collected from the quality log.
CAD integration A more elaborate method of handling drill fans and planning of production drilling is to integrate the Simba drill rigs with the CAD/planning system at the mine site. This means that there is no need for manual handling or design of fan plans in the mine. The fan plans are designed in the CAD system according to known or anticipated ore boundaries.
In a CAD system the mine design exists in a 3-D model. The ring design package of the CAD system generates a fan plan for the Simba and exports it in IREDES format. The fan plan is transferred into the Simba via the mine network or by means of a PC card. The operator of the Simba accepts the
fan plan, navigates navigates the drill dri ll rig, drills dril ls the fan, and saves the quality log file back to the CAD system. At the moment, integration exists be-
tween Simba RCS and Surpac, Vulcan
the ore.
To ensure efficiency in the mini mining ng process the Atlas Copco Simba production drill rig can be used to drill just in the ore and avo avoid id drilling, drill ing, charging and blasting areas with pure waste. A well-designed fan plan adapted to the actual ore deposits, correct drill rig
navigation, accurate drilling, precise explosiv expl osives es loading, and correctly timed t imed
blasting all ensure a good production result. The Simba with RCS assists the miner to fulfil these requirements and to control the grade of the ore.
Since introducing the Simba M and L Atlas Copco has delivered a great number of Simba production drill rigs
ing time is short, and a nd beginners and ex-
days of training. To use new technology t echnology like CAD integration requires some training in new standing of the mine design drawings.
Precision drilling, high productivity and swift availability are the criteria for low low
cost and successful longhole production drilling. dril ling. With the RCS technology, technology, Atlas Copco gives the driller the oppor-
tunity to undertake longhole drilling with faster and more reliable control of
the entire operation, while improving drill string str ing life and reducing costs per drill metre.
As all mines are, above all, chasing costs, the range of high precision drill rigs gives the mine planners and stope designers design ers opportunities to better optimize the mining process and thereby savee costs and increase sav i ncrease productivity.
of 7 different configurations of compu-
terized production drilling equipment. The modular concept of mechanical,
PRODUCTION DRILLING IN UNDERGROUND MINING
Patrik Ericsson 25
TALKING TECHNICALL TECHNIC ALLYY
Simba M6 C- IT ITH H drilling downholes.
26
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Faster Fas ter Simba Simba rigs set the the pace Great opportunities The ultimate objective for all miners is to reduce the cost per tonne of ore produced, and this goes hand in hand with the overall effort to introduce more efficient mining methods and equipment. The Simba range of high precision production drill rigs represents a concept that makes the drill rig productive and easy to operate. Fast and exact positioning and collaring, sturdy construc tion and small hole deviation, fast rodhandling, reliable automatic functions, good exploitation of r ock drill power, simple and quick servicing and high transport speed make the Simba M– and L– models Atlas Copco's most efficient generation. But perhaps the real cost saving potential for mine management lies in the new opportunities to better follow the ore boundaries, to reduce the drilling density and to reduce development by spacing the drill drifts and sublevels further apart. Simba production drill rigs incorporate a solution for every drilling application.
Advanced technology Atlas Copco launched the M and L series in September, 2001 to replace the previous generation of Simba drill rigs.
Designed with precision drilling, high productivity and swift availability in mind, the Simba production drill rigs
are engineered around the Rig Control System RCS platform, a flexible and easily expandable control system that has already been used to great effect in
the Boomer range of face drilling drilli ng rigs. Significantly, the technology provides for varying degrees of rig automation and, ultimately ultimat ely,, the possibility of fully automated and remotely monitored drilling.
Thanks to this advanced, and easy to learn, lea rn, computer-based technology, the M and L series Simba rigs can be integrated into the total planning of the mining operation, with a level of
The Simba M and L series production drill rigs inc orporate nine different drill units, units, three feed lengths, six rock drills and an extensive options programme.
monitoring and detailed control that hitherto has not been possib possible. le. Further
Simba range
potential for increased productivity can be achieved through improved precision
Precision drill ing, high productivity and good availability are fundamental
and better control, which allow the
requirements for low cost and successful production drilling. Designed with these
operator to drill long longer er and larger holes, with greater spacing and burden.
PRODUCTION DRILLING IN UNDERGROUND MINING
criteria in mind, m ind, the range of Simba M 27
TALKING TECHNICALL TECHNIC ALLYY
RD = Ring drilling PH = Parallel holes
1500 (PH)
Dimensions in mm
drilling, and can drill parallel holes up to 3 m apart, making the machines
Stingerextension Stinger extension 0 0 5 0 1 9 1
o
5 1 9 4
3 0
R 2 9 7 0 ( R D )
) n 0 o 0 i 9 s ( n 0 e t 0 x 2 e 1 d e e F
3 0 0 o
380o 5 2 8 1
150 7440
Stinger extension Stingerextension 2000
Type M3
3000 (PH)
Dimensionsion mm
Stingerextension Stinger extension 0 0 5 0 1 9 1
0 5 0 1 6 9 4 4
750 1500 R 2 9 7 0 ( R D R 2 7 380o ) 79 0 9 ( P 0 PH ) H )
o
3 0
750
) n 0 o 0 i 9 s ( n 0 e t 0 x 2 e 1 d e e F
3 0 0 o
1 5 0 0 ( P H )
5 2 8 1
150 7440
Stingerextension Stingerextension 2000
Type M4
the machines can also be equipped e quipped with
porate a solution for every drilling
RHS rod handling handli ng system for mecha-
application.
nized drilling.
The complete range features the following models: M3 C, L3 C, M4 C, following M6 C, L6 C and M7 C. The models M3 C, M4 C, M6 C are also available for in-the-hole in-the-hole hammer drilling d rilling (ITH). (I TH). The range is broadened by the availability of an array of options such as rod handling systems, extractor units
For ITH capability, COP 34, 44, 54 and 64 hammers can be supplied for hole diameters of 95-178 95-178 mm.
Breakthrough Automatic Stop, MWD Measure While Drilling and upgrades of the level of automation to ABC
All Simba production drill rigs are based on the sturdy modular designed articulated articu lated M-carrier, and are powered by a Deutz low low-emission -emission diesel engine (Stage III/ Tier III). Rated at 112 kW kW, this particular engine provides for longer life, lower maintenance and operational costs, and, above all, fast tramming speeds of up to 15 km/ h. This makes the Simbas particularly
Regular and ABC A BC Total. Total.
effective when negotiating negotiating steep ramps
The COP 1838 1838 rock drill is fitted f itted as standard across all t he new M series and is suitable for hole diameters of 51-89 mm or 89 COP HEX for 76-89 mm diameter holes. The two L
or inclines. Other features include high ground clearance, four-wheel traction, and articulated steering for easy manoeuvring, while an optional silenced FOPS-approved cabin, with panoramic view, affords an improved
series models, meanwhile, are equipped with the powerful COP 4050 rock drill
working environment for the operator.
for drillhole diameters ra nging from
Five different positioning systems
89-127 89-1 27 mm. m m. Consequently, Consequently, these t hese larger
are available through various combina-
rigs are equipped e quipped with a larger la rger power power
tions of the pendulum, the slide table
pack than the M series (2 x 75 kW rather
and, in the case of the M3 C and M4 C
than 2 x 55 kW) to match the require-
models, an optional turntable. All of the new Simbas offer 360 degree ring
ments of the much larger larger rock drill. dril l. All
purposes: • To practically eliminate jamming and the subsequent loss loss of drill dril l strings stuck in holes; and • to assist in the uncoupling of drill string joints.
reversed percussive effect equal to around 20% of the conventional drilling impact
and L series production drill dri ll rigs incor-
for the rock drills, dril ls, air/water-mist air/water-mist flushing, additional stingers, water reel, BAS
productivity and cost efficiency, particularly in difficult rock conditio conditions, ns, an extractor unit is available as an option for the COP 1838, COP 2250 and COP 4050 rock drills. This unique back hammering device serves two main
The back hammering action is a
Simba type M4 drilling configurations.
28
All tophammer rock drills for the Simba rigs are equipped with a dual damping system, which means that more impact energy can be exploited without increasing wear in the drill steel – in other words, higher produc tion for the same, or a lower, lower, cost. To further fur ther enhance longhole drilling
Simba type M3 drilling configurations
RD = R ing drilling drilling PH = Parallel holes
ideal for longhole drilling applications, such as in sublevel stoping and sublevel caving.
energy. This reduces the rod handling time between holes by eliminating jammed joints, joints, as well well as reducin reducing g wear wear on gripper jaws, the shank and the drill. A jammed drill string can also poten-
tially represent a significant replacement cost for a mining operation or contractor. Once again, the incorporation of the extractor can minimize such
costs through its ability to actively back hammer on the jammed string to remove the obstacle.
The improved drill unit, with up to four stingers on the drill feed, provides a
solid set up. The aluminium feed incorporates two hydraulic stingers mounted directly on the feed beam as standard, and can be equipped with a further two for ‘rock solid’ positioning in particularly difficult conditions. This provides improved stability in the set-up of the feed, which is extremely important in collaring and dri lling straight holes. With the help of the stingers the drilling unit is supported during the drilling dril ling process.
The stingers absorb the side forces during collaring collari ng and remove remove the stress created by the feed force. The combined
drill steel support/guide can also be
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
easily adapted for different combinations of drill steel and drill tube. t ube. The double-bottom feed beam easily
withstands the high stresses involved when drilling, while the double action hydraulic cylinder, with its direct coupling to the cradle, gives smoother and steadier movement of the rock drill. Thanks to the replaceable wear pads and easily adjustable cradle, centring of the rock drill can be maintained witho without ut difficulty.
Extendable intelligence The heart, heart , or perhaps more accurately accurat ely,, the brain, of the new machines is the RCS platform, which not only allows the rig operator to drill faster and with much greater precision, but also simpli-
fies the drilling dril ling functions and trouble shooting.
The RCS allows for extendable intelligence, provides a good operator interface, and has the potential to be linked up
to mine planning software. The system affords three thre e levels of automation automation – Basic, Regular and Total.
At the ABC Basic level of automation, all drilling dril ling operations are manually controlled from the operator’s panel and its large display screen. To enhance
the quality of the drilling, functions for angle of drilling and hole depth measurementt are uremen a re incorporated as standard, along with statistics statist ics logging and event logging to help in preventative mainte-
The advanced hydraulics system has enabled Atlas Copco to reduce the total hose length by around 30%, which dramatically improves the operator’s line-of-sight, line-of-sight, as fewer hydraulic hoses are linked to the control panel or fed into the cabin.
nance.
and to improve i mprove the penetration rate. To
Ultimately, the drill rig can be fully
has enabled Atlas Copco to reduce the total hose length on the Simba production drill rigs by around 30%, which provides for higher machine availability owing to fewer hose failures. Furthermore, the introduction of RCS has simplified cabling significantly,
automated if equipped to the ABC Total
and the system is programmed for self-
level, with the operator using the control and display panels only to set up and initiate automated sequences such as automated multi-hole drilli ng. As a result, only one, or a team of a few
diagnosis, making trouble shooting much easier. e asier. Together ogether,, the combination of the RCS and the proportional propor tional hydrau-
measured rotation pressure, to further increase the penetration rate without risking the life of the drill. If rotation resistance becomes be comes excessive, excessive, an
lics provides greater drill precision and
anti-jamming function is activated, and
smoother positioning, positioning, particularly during
the collaring collari ng sequence for a new hole
operators at most, is required to operate and supervise several several drill dr ill rigs. r igs.
hole collaring. Hydraulic oil leakage is
is initiated. As well as improvin improving g the penetration rate, the RCS maximizes the life of the
Incorporating all the functions of ABC Basic, the ABC Regular level of automation allows the operator to initiate automated single hole drilling. Extended logging logging capability and dril l plan handling are available as options.
Monitored and controlled from the operator’s panel, each drilling function
also kept to a minimum, for example due to hose failure, by automatic shutdown of the hydraulic pumps.
optimize penetration rates in different ground conditions, as well as in different drilling directions, the control system constantly monitors changes in the rock conditions, and adjusts the drill feed pressure, depending upon the
shank adapter, tubes and drill bits by
is handled by dedicated, locally posi-
By also enabling smoother control
ensuring that the tube joints are a re tightened
tioned modules that are interconnected through a CAN-bus network. The RCS
of the drilling operation, the RCS platform helps helps to minimize drill dr ill steel stress
with a constant torque throughout throughout the whole who le length. At the t he Zinkgruvan Zinkgr uvan lead
PRODUCTION DRILLING IN UNDERGROUND MINING
29
TALKING TECHNICALL TECHNIC ALLYY
3000 (PH)
RD = Ring drilling drilling PH = Parallel holes
Dimensions in mm
Stinger extension extension 0 0 5 0 1 9 1
Feed extension 1200 (900)
o
0 5 6 0 5 0 0 5
R 4 8 8 0 ( R D )
3 0
4 5 o o
4 5 5 o
o
4 5
R D ) ( R R 2 76 0
380o
0 8 7 2
150 8520
Stinger extension extension 2000
Type M6 Simba type M6 drilling configurations.
and zinc mine mi ne in Sweden, for example, example,
was introduced on the Boomers some
drill tube li fe has increased from the
three years before the launch of the new generation Simbas.
1,200-1,300 m being achieved with the 1,200-1,300 mine’ss earlier rigs, to more than 1,800 m mine’ with its Simba M4 C.
Components that require regular Components service are especially easy to get to, and the Simba production drill rigs have been designed so that they can be readily dismantled into their main components, for ease of lowering into
Spare parts and consumables for the Simba rigs are, for the most part, the same, so technicians familiar with the other RCS rigs should have no difficulty in finding their way around the
Significantly,, the RCS system is Significantly capable of accepting new software, which can be easily extended. Another
narrow shafts.
The RCS Simba production drill rigs incorporate features and components found on the Atlas Copco RCS r igs.
standard equipment and systems is a great advantage to maintenance operations, and much effort has gone into making each module easily accessible
Such development development of standardized standardiz ed equipment and systems has important implications for both the mine and the manufacturer. The mine is no longer dependent on tailor-made, or special, solutions for its drilling requirements, while the overlap between the product families has enabled Atlas Copco to reduce the assembly lead times at its
These include the RCS platform, which
for maintenance.
factory.
important feature is its easy integration into other systems.
new Simba drill rigs.
Indeed, the same modular design concept, as in other RCS rigs, provides a better serviceability serviceability.. Being able to use
Modular overlap
All of the new Simbas offer 36 0 degree ring drilling and can drill parallel holes up to 3 m apart, making the machines ideal for longhole drilling applications such as in sublevel stoping and sublevel caving. Dimensions in mm
850 Stinger extension
0 0 7
1200 (900) Feed extension 5 0 1 1
0 4 1 6
0 0 6 1 o
1 0 0 5 8 7
90o 45o
25o
Parallell holes with 0o boom-lift 35o boom-swing Coverage area 1100x4690 mm Dimensions with 45o boom-lift 25o boom-swing Dimensions with 0o boom-lift 35o boom-swing
35o o
360
0 0 9
150
Type M7
30
2000 Stinger extension 3900
1600
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Zinkgruvan experience
2002, to some 900,000 t/y, using sublevel open stoping and longhole open
The first of the new generation Simba drill rigs was delivered in September, 2001 to the underground Zinkgruvan
stoping with paste fill. The latter method was introduced to
lead and zinc mine, just a few hours drive
from Atlas Copco’s drill rig manufacturing facility at Örebro, in Sweden. Historically, the mine actually encompassed three separate operations, but, but, more recently, recently, access tunnels have been
driven to link the entire operation together. Whilst this has meant improv i mproved ed equipment utilization, the tramming distances for such equipment is now much
longer. Production is currently being ramped up from around 850,000 t/y in
eliminate t he need for post-mining of pillar remnants, and because of poor rock conditions.
Hydraulic oil spillage is almost a lmost totally • Hydraulic eliminated, owing to a 30% reduction in hoses and a smart smar t oil leakage shutdown system. • The easy-to-learn CAN-bus system, which simplifies trouble shooting. In November, 2002 Zinkgruvan took
The mine has identified four major improvements with its Simba M4 C
delivery of its second Simba M-series
compared with the rig’ r ig’ss predecessors: • The new rotation unit provides much better precision, especially beneficial when drilling opening slots. • The four stingers afford a more stable
primarily for drilling 54 mm-diameter cablebolt cablebo lt holes. Around 50,000 m/y m /y of cablebolting is carried out at the mine. The rig will also be required to fill in as a production unit, drilling 76 mm-
feed setup, giving good precision in hole alignment, collaring and during
machine, an M7 C that will be deployed
diameter holes.
Patrik Ericsson
drilling.
With an entirely new frame, nine different drill units, three feed lengths, six rock drills and an extensive options programme, Atlas Copco can offer the right Simba for every application.
Simba modular program with maximum flexibility flexibility Type 4 Positioning: Rotation, 380° Tilt forwards, 30° Tilt backwards, 30° Side movement, ±1.5 m with sliding table Extra side movement, ±0.75 m with pendulum arm
Type 3 Positioning: Rotation, 380° Tilt forwards, 30° Tilt backwards, 30° Side movement, ±1.5 m with sliding table
Type M COP 34,44,54,64 COP 1838ME/MEX
Type L
Alternative pendulum arm with 90° turned feedholder
COP 1838HE/HEX COP 2550UX COP 4050MUX
/L33 Type M3 M3/L Type 6 Positioning: Rotation, 380° Tilt forwards, 45° Tilt backwards, 30° Sideways, ±1.5 m
Type M4
Canopy Telescopic and FOPSapproved
Extra: Turn table ±20° Cabin with panoramic view and FOPS-approved
Engine module
Rear module
Type 7 Positioning: Reach, 3.5 - 5.1 m Rotation, 360° Boom up, 45° Boom down, 15° Sideways, Sidew ays, ±35° Forwards, 90° Backwards, 10°
Type M6/L6
Front module
Type M7
7 0 0 2 G R E B M L O H A
Power pack
© Atlas Copco 2003
PRODUCTION DRILLING IN UNDERGROUND MINING
31
TALKING TECHNICALL TECHNIC ALLYY
Simba M7 C.
32
PRODUCTION DRILLING IN UNDERGROUND MINING
TALKING TECHNICALL TECHNIC ALLYY
Increased productivity with ITH IT H dril drilliling ng
ITH growing in popularity The ITH drilling method is growing in popularity, with increases in all application segments, including blasthole, water well, foundation, oil & gas, cooling systems and drilling for heat exchange pumps. ITH competes favourably with rotary drilling in open pit mines, mainly thanks to increased productivity and flexibility. Open pit mining has adopted smaller holes where rotary drilling has either been replace d by ITH, or where ITH has been introduced to create a better finish to the pit wall, as the method is also perfect for pre-splitting pre-splitting and smooth blasting, which avoids back-cracking. ITH drilling offers increased productivity, and is favoured by contractors for production drilling. In larger quarries, the optimum hole size is 110-140 mm. With today’s demands for strict hole control for safe blasting in populated areas, ITH drilling is a popular choice among quarry operators.
deep hole drilling drill ing capacity, with constant penetration and no energy losses
Cutaway section of Secoroc COP 64 Gold.
in joints; and efficient energy transmission, with the piston striking dire ctly on the bit.
gavee another boost to the sales of hamgav
The COP 34-84 series of hammers ham mers was introduced from 1992, and imme-
mers. The flexibility, productivity and manoeuvraa bility of these rigs, when manoeuvr equipped with a COP hammer, makes them the most productive combination
diately became the benchmark for productivity within ITH drilling. Over the
on the market today today..
years, the increase in average drilling pressure, from 17 17 bar to a current
COP 64 Gold
market standard of 25 bar, has improved hammer performance, and productivity has increased proportionally to air pressure. The introduction of the Atlas Copco
The increase in drilling pressure also had some negative impact on the internal components of the ITH hammer, as the increased stress promoted the
ROC L8 and L6 series of highperformance, high-pressure ITH rigs
New Secoroc hammer and bit ready for action on an Atlas Copco drill rig.
Quality holes In the hole range 100-254 mm, ITH drilling is the dominant drilling method
today. The main features of ITH drilling in this hole range are: excellent hole straightness within 1.5% deviation without guiding equipment; good hole cleaning, with plenty of air for hole cleaning from the hammer; good hole quality, with smooth and even hole
walls for easy charging of explosives; PRODUCTION DRILLING IN UNDERGROUND MINING
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risk of premature failures. So, in i n 1998, 1998,
COP 64.2 steel COP 64 Gold steel Improvement
Atlas Copco Secoroc decided on a long-
term strategy to improve reliability, while retaining the benchmark status of the COP 64 ITH hammer.
Stage One of this strategy was the development of the second generation
Yield point ReL(Mpa) Breaking Breakin g stren strength gth Rm(Mpa ) Hardness (HRc )
700 1000 32
1400 1950 42
100% 95% 31%
Table 1 reveals not only that the yield point for the new steel grade is twice as high, but also that breaking strength has been almost doubled.
six-inch hammer, COP 64.2, introduced
in October, 2000, which incorporated i ncorporated newly-designed steel disc spring and lower buffer. Performance was vastly
Table 1 Comparison of COP 64.2 and COP 64 Gold steel.
this means customers can look forward to increased drill rig availability. The sum total of these improvements
In soft unconsolidated rock drilling, the 12-spline chuck concept and the improved durability make COP 64 Gold the perfect hammer. High pressure
without diminishing its performance,
shows COP 64 Gold to have more than shows 50% greater service li fe, in abrasive abrasive
making it even more attractive.
rock conditions, than its pr edecessor.
pressures of 28-30 bar are not unusual.
improved, thanks to a drastic d rastic reduction
in the number of internal failures. It was also possible to rebuild the hammer
Stage Two Two was the t he introduction of the third generation COP 64 hammer, COP 64 Gold, which was unveiled in August, 2001. This version offers sustained performance and improved longevity of the external parts. The COP 64.2 resolved internal component reliability, while the COP 64 Gold has experienced a dramatic drop in the number of cylinder failures.
COP 64 Gold also boasts improved sustainable efficiency, maintaining an
The customer benefits from lower
The COP 64 Gold hammer concept
cost/metre drilled, thanks to less down-
offers customers a tool to meet the most exacting requirements.
time and greater abrasion resistance, and 30-50% longer life of external parts.
Higher availability results from less breakage in the threads of top sub and chuck-ends of the cylinder, and there are
fewer stoppages for service and maintenance. Improved penetration rate and higher efficiency are a result of reduced
average of 96% of original performance
friction of the piston, and a greater life cycle penetration rate is the overall
throughout its service life, which is a
reward.
further improvement on COP 64.2.
Durability improvements, thanks to the higher tensile strength of the new steel grade, are especially noticeable
yields higher productivity, productivity, and drilli drilling ng
Hammer cylinder The new cylinder has been redesigned in a number of important ways. COP 64 Gold boasts a cylinder made of low alloy wrought and toughened steel, a new grade with a higher combined Molybdenum and Vanadium content (4.8%) (4.8%) than its predecessor. The result is grea-
To sum up, the customer can drill
ter impact strength and higher wear and temperature resistance. All in all,
more holes per hammer than previously.
this means greater resistance to brea-
kage, impact, temperature and wear for
Applications
the new hammer cylinder.
thickness limits. COP 64 Gold enjoys a greater durability margin than its
COP 64 Gold is a high-pressure hammer, where performance is related to
linder properties have been greatly im-
predecessor.
air pressure. A lower limit of 12 bar for deep hole applications is a good rule of thumb. The hammer is designed for the same types of application as COP 64.2,
when the cylinder approaches minimum
With the introduction of COP 64 Gold, hammer life will increase substantially.. Less internal and external stantially wear, together with a reduced minimum cylinder wear limit, are key contributing factors. The hammer is virtually maintenance-free, with no need for an economy kit in most applications. Ultimately,
Thanks to the new steel grade, cyproved. Wear has been proved. be en reduced, both internally and externally external ly.. Cuttings and moving parts no longer cause the problems they once did. In effect, the service
with special focus on high-pressure applications. In abrasive formations, performance will be up to 50% better than COP 64.2, in what is an ideal ap-
life of the cylinder has been extended considerably con siderably.. The new steel grade possesses greater tensile strength, which means the minimum wear lim it can be decreased from an overall cylinder
plication for COP 64 Gold.
diameter of 132 mm, to 130 mm.
Secoroc COP 64 Gold.
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Total improvement Due to wear resistance Due to wear limit change Due to less cylinder failure
Increase in service life of COP 64 Gold, which has a 50% longer life than its predecesssor.
The result is a hammer that maintains performance far longer than its predecessor, while being, in effect, maintenance-free.
Longitudinal milled slots have replaced the circular undercut found in COP 64.2. The piston now enjoys 100% guidance througho th roughout ut its stroke, st roke, as opposed opposed to the older undercut that
The polygon-shaped piston provides a ten-point guide system, while retaining retaini ng excellent excellent force on the bit. It is sturdier than its forerunner, fitting hand-in-glove with the milled slots to provide superior guidance and airflow all the way through the hammer.
The QL 60-style chuck, together with a 12-spline bit, add up to a stronger
let it partially partia lly move freely at the end of
bit shank. This is especially useful in
the downward stroke. Thanks to these slots, wear on the porting edges of the cylinder undercuts and piston has been eliminated. That means air leakage is down to a minimum, and so a re noise
soft and unconsolidated rock conditions,
levels!
in the number of splines, from eight to twelve, twelv e, leads to greater surface contact between bit and chuck, lessening stress on the splines.
The high demand for COP 64 Gold hammers, particularly part icularly in applications where performance and reliability are major considerations, has led Atlas Copco Secoroc to add the COP 54 Gold to this increasingly successful range.
where bits tend to move axially in and out in the chuck during drilling. This may lead to greater fr iction between chuck and splines, causing premature spline wear. Furthermore, the increase
Leif Larsson and Patrik Ericsson
Results of comparative tests with COP 64.2 and COP 64 Gold. The COP 64 Gold drilled 50% further.
16 000 14 000 12 000 s e r t e m l l i r D
10 000 New Material Old Material
8 000 6 000 4 000 2 000 0 146 145 144 143 142 141 140 139 138 137 136 135 134 133 132 131 130 129 128
Cylinder OD (mm)
PRODUCTION DRILLING IN UNDERGROUND MINING
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Simba M6 C-ITH.
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Tuning up your drilling system Optimum combination of factors Choosing the right rock drilling tools and adjusting all the settings in the drilling system can boost performance and cut costs, but it’s not always easy. To discover the optimal combination, a customer can compare test results step by step – or use rock drilling simulation such as Atlas Copco’s Diarot package.
Complex parameters A rock drilling system is complex and many parameters decide its performance. Taking into account the rock characteristics, these parameters include: • bit diameter, design and button type; of flushing media used; • type of drilll rod type and geometry; • dril • piston mass and geometry; velocity of the • the frequency and velocity rock drill impact piston; • rotation speed; • feed force.
To get the most out of a drilling system, all these factors must work in harmony. The system should also match
the overall excavation method. This means that fragmentation for loading and crushing is another consideration.
The bit that counts A combination of drill bit, drill rods, shank adapter, rock drill and drill rig determine the performance of the rock drilling system, and this is an area in which Atlas Copco has considerable knowledge. Here we want to focus on the drill string, i.e. i.e. the drill bit, rods and shank adapter.
Three parameters para meters should be considered when choosing a drill bit. They
Figure 1: Ballistic buttons (left) and spherical but- tons: The ballistic buttons are generally co nsidered the best choice for most rock drilling applications.
This efficiency also gives g ives the best hole straightness and we recommend ballistic button bits for most applications. Additional reasons are: • The larger protrusion makes it easier
the hole to a given diameter. The bit’s ability to penetrate the rock efficiently depends on how well the contact between the surface of the buttons and rock is established, their buttons’ shape and number, the bit’s flushing characteristics and the brittleness, or drillability drillabil ity,, of the rock. Tests have shown that the relatively relat ively smaller contact surface and the la rger protrusion of the ballistic button help to break the rock more efficiently giving higher penetration rate than the spherical button (see Figures 1 and 2). Figure 2: How the buttons bite: Under the same impact energy the ballistic button will penetrate deeper into the rock, since it has a smaller contact area (footprint) than the spherical button.
to clean the hole, leaving the bit to deal with ‘fresh’ rock, thereby avoiding secondary crushing. • Atlas Copco Secoroc’s patented
grinding system, using a profiled diamond grinding wheel, maintains the performance of the bal listic button by restoring its original profile, which is essential for optimum penetration rate and service life (Figure 3).
However, spherical buttons are still preferred in certain types ty pes of hard and
Additional Penentration
are: • Penetration rate • Hole straightness • Service life
In 95% of all percussive rock drilling, a button bit is selected to drill PRODUCTION DRILLING IN UNDERGROUND MINING
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Figure 3: Bit grinding shop.
After the button bit, we should examine the drill rods and shank adapter. The
task is to transfer the rock drill piston’s abrasive rock formations, where they can have a superior service life.
Perfect partner The design of the drill bit, especially the number, placement and shape of the t he buttons, makes it the perfect partner for
the rock drill and its percussive energy to press the buttons into the rock. If the power of the rock drill is insufficient, or
energy through the drill string and drill bit into the rock. The COP 1838 hydraulic drill piston impacts on the drill string 50–60 times a second and, each time, the buttons penetrate 0.5–1.5 mm into
the rock. If the design and setting of the drill ing equipment equipment is matched to the rock, energy transmission will be nearly optimal optimal and t his, in turn, will affect the service life of the drill string stri ng
in energy loss and drill string failure
positively.
Rigid rods pay off
the buttons are worn too flat, the penetration rate decreases and hole deviation increases. In addition, the risk of
When the piston in the rock drill strikes the shank adapter the kinetic
damaging the buttons increases with the size of the wear flat. There is also a risk of drilling with non-tightened couplings due to lack of rotation torque, something that leads to short drill steel life.
compressive stress wave, which travels
Using the Diarot rock drilling simulation system Atlas Copco is able to simulate the performance of different
rock. In a mismatched drilling dril ling system, some of the energy in the stress wave will be reflected and returned back up the drill dril l string stri ng as a tensile stress wave. wave. Tensile stress wav waves es a re much more detrimental to the drill string in com-
drill bit designs, using data from a worksite or from its extensive database.
energy of the piston is converted into a
through the drill string and into the rock and breaks it. In a well-tuned rock drill-
ing system, most of the energy in the stress wave is being utilized to break the
(Figure 4), which can be simply detected by measuring the temperature on the t he coupling.
There are different types of rods in the Atlas Copco Secoroc range and we recommend the Speedrod, with integrated couplings for extension drilling (Figure 5). A drill string with Speedrod gives faster penetration than one with extension rods and couplings, as less energy is lost at the joints. Furthermore, the Speedrod’ss threads are Speedrod’ a re easy to keep tight
during drilling, giving very efficient energy transmission.
The drill string’s joints must be tight enough for energy transmission
Drill rods must be selected to suit the entire system. The largest possible rod diameter for the hole dimension is recommended. A larger-diameter rod has a longer service life (be cause of
to be fully fu lly effective. effective. Loose joints result
less stress per unit area – sq mm) and
parison to compressive stress waves. Figure 4: Extension rod joints must be kept tight during drilling. Loose joints cause overheating and energy loss, drastically reducing efficiency.
Figure 5: Secoroc Speedrods and MF drill rods.
because it transmits more energy per blow. Furthermore, large rods are also more rigid and, in the same way as TDS
guide tubes, will give straighter holes and better blasting results. Finally, to make the whole system work as efficiently as possible, the drill rods must also suit the rock drill, its piston and shank adapter.
Alf Stenqvist
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Computer based training training for rock drilling drill ing tools Latest version Atlas Copco Secoroc recently introduced version 4.0 of its Computer-Based Training (CBT) package as being of paramount importance in achieving the highest level of competence in rock drilling tools among distributors and customers, as well as its own sales force. Correct understanding of how to choose, use and maintain the rock drilling tools affects profitability for all, and adds to competitiveness. Atlas Copco Secoroc believes that the CBT package for rock drilling tools is the most comprehensive interactive training tool available in the industry today.
Expert knowled knowledge ge The course is based on the skills and experience gained by key Atlas Copco Secoroc personnel over many years, and conveys expert knowledge in the use of modern rock drilling products. CBT Rock Drilling Tools version 4.0
Main menu. This is the first picture shown when you start the C BT BT.. From this main menu you can choose which of the courses you would like to enter.
was released after six years of patient development.
Course menu. View picture for the course Raise boring. Under the text “Introduction” you find two buttons, “Learning objectives” will explain what you are expected to learn. “Introduction” will give you an overview by running pictures and a s peaker talking. Under “Lessons” you choose chapters.
Computer based training transfers knowledge about drill string products
and their use, in a simple and efficient way. Aided by 3-dimensional animations, photographs, film sequences and
interactive lessons, the training course explains how the market’s leading drill string products can increase both productivity and profit.
With version 4.0, CBT now includes training on Atlas Copco Secoroc products, with: separate packages divided into tophammer, ITH and raise-boring; separate libraries for drilling equipment
and applications in all packages; updated product training section on tophammer equipment including troubleshooting, bit grinding, and care and main-
tenance; product training section on ITH equipment including troubleshooting, bit grinding, and care and maintenance; product training tenance; trai ning section on consumables for raise boring equipment,
including care and maintenance; ma intenance; focus tests on each lesson; and a new new section section of product selection exercises. exercises. PRODUCTION DRILLING IN UNDERGROUND MINING
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Chapter. In this section you choose the lesson you want. In the lower right corner you find four buttons. ”X” will finish the actual step. Number two will take you back one step. The third button allows you to scroll through the course.
Lesson. There are three buttons for presentations. Video cam era button: running pictures and speaker text. Photo camera button: pictures from more important or difficult parts. Text button: pictures and text.
Step player. When pressing the step player button you will find film sequences or animations. At the end of every lesson you can also go through a test, “Focus test”, to check your knowledge.
Product selection exercises. At the end you also have the possibility to go through some “real” exercises, where you will have the background for a specific rock excavation and from that choose suitable equipment to do the job.
Complete training The whole Secoroc CBT Rock Drilling Tools package comprises approximately
50 hours of lessons and tests. With a recommended maximum of four hours of lectures per day, the total length of a complete training course on rock drilling tools can be estimated at three weeks.
CBT enables efficient training whenever the need arises. For instance, a 40
new employee can start the learning process right away, and learn about how the product is manufactured, its characteristics, wear limits, and much more. A modular structure enables users to study lesson by lesson, or in a selective way at their own pace. With personal computers, learning can take place whenever and wherever the individual chooses, including in the field. The training package teaches you to find the right tool for any given rock
drilli ng application drilling application at any time of the day.. Experience with CBT version 2.0 day resulted in good market acceptance of version 3.0, which has been successfully advising both key customers and technical schools. The new version of CBT 4.0 is expected to contribute further to the added value in Atlas Copco Secoroc sales service.
Björn Samuelsson
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The econom economic ic case for routine routine bit grinding throughout its life, maintains the t he correct button shape and pro trusion. It
Cutting hole costs The button bit was originally developed to do the job of an insert bit, without the necessity for frequent grinding. However, it was soon found that the service life of a button bit increased considerably if the cemented carbide buttons were ground. Nowadays, it has become extremely important to grind button bits at proper intervals, in order to extend the service life of the rock drilling tool, maintain penetration rates, and drill straight holes. In all rock excavation operations, the cost is usually expressed expressed in cost per drilled metre (cost/dm), in cost per cubic metre (cost/cu m), or in cost per tonne. The cost to produce a hole depends on how fast it can be drilled, and how many tools will be consumed. The cost to produce a cubic metre of rock is dependent upon the cost of the hole, and the cost of blasting. If the blasthole is of poor quality, then more explosives will be consumed in blasting the rock. Unsharpened bits very often give a poor quality hole with deviation. Grinding consti tutes around 2% of the costs of the entire drilling operation. To run the business without grinding could multiply this cost, with up to 100% added when production losses are taken into account. Labour and material are the highest costs, while the machine investment cost is low when utilization is high, with a large number of bits to be ground.
features correct centring on all buttons, producing a high quality cemented car-
bide surface, with no risk of cemented carbide nipple. Long bit life, and higher penetration rates, will result from good grinding quality.
Disadvantages of using the grinding cup are that it may produce an incorrect button shape and protrusion. It is difficult to centre the grinding cup over the gauge button, and there is also a risk
of producing a sharp cemented carbide nipple on the button, and a possibility of scratches due to the larger diamond grain used. Reduced bit life will result from poor grinding quality.
Several tests hav Several havee been carried ca rried out to find which method gives the best bit performance. The grinding wheel gives the correct shape to the button,
The Secoroc Grind Matic BQ2 grinding machine can handle drill bits up to 127 mm in diameter.
regardless of the amount of wear on the wheel, ensuring that the bit will achieve
Diagram 1: Typical bit life grinding at different intervals.
700
Total bit life drill metres
600
10 regrindings per drill bit
500
400
300
Grinding methods
200
There are two different methods of bit grinding to restore the button buttons. s. The pre-
ferred method uses a diamond coated profiled wheel, and the other, a grinding cup. The profiled wheel provides a smooth and efficient grinding operation, oper ation, which, PRODUCTION DRILLING IN UNDERGROUND MINING
Grinding interval drill metres
100
0 10
20
30
40
50
60
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and circulate in the hole, causing secondary damage to the buttons.
When a bit doesn’t show any visible wear flat, it may be suffering from
micro cracks on the cemented carbide surface. This is known colloquially as snakeskin, and can be clearly seen when using
a magnifier. In this case, the surface has to be ground away, away, otherwise the micro cracks lead to more severe damage on the buttons. Likewise Li kewise,, buttons which protrude too much must be ground down to avoid damage (Diagra m 2).
Penetration rate When the right bit has been chosen for the rock condition, it will provide maximum penetration rate, along with acceptable hole straightness. In rock conditions like Swedish granite, with a compressive strength of around a round 2,200 bar, the bit gets a wear flat after
Diagram 2: Risk of total loss when a bit is overdrilled.
just 10-20 10-20 drill metres, accompanied accompanied by
a small drop in penetration rate. When standard penetration penetrat ion rate throughout its
There is always a sharp edge created
it has a wear flat equivalent to one-third
entire life. It has also been shown that bit life is increased considerably when grinding wheels are used, rather than grinding cups. Wheels also excavate
on the button, and this becomes sharper
of the button diameter, the penetration will have dropped by 5%. If the bit is used further until it has a two-thirds wear flat, t he penetration will have
steel around the button, simplifying the grinding task, and a nd giving the bit a more exact profile.
the more the bit is overdrilled. This sharp edge, especially especially on ballistic buttons, is very brittle. Once the edge cracks, pieces of cemented carbide break brea k away
dropped more than 30% (Diagram 3).
Diagram 3: Penetration rate drops as the b utton profiles flatten.
Bit life With so many parameters involved, it is difficult to estimate bit service life. First, a proper grinding interval must be established, preferably at the stage when the button has a wear flat of one third of the button diameter. When the number of drilled metres to reach this stage has been established, then a calculation of bit life can be made, by multiplying by the number of times it can be
reground. As a general rule, a bit can be reground 10 times, but smaller bits may achieve slightly less than this figure, while larger bits may achieve more. So, if the grinding interval has been established as 60 drill metres, then the average bit life will be 660 drill metres (Diagram 1). If a bit is over drilled, and the wear flat is more than half of the button diameter, there is a tendency towards towards cracked buttons. 42
PRODUCTION DRILLING IN UNDERGROUND MINING
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are available. The machine is driven by
9
up to 7 bar compressed air, and is suit-
8
able for a small grinding operation.
Grind Matic Manual B is an air-
7 6 5
Labour cost
driven portable grinder using diamond-
Grinding material cost
coated grinding wheels for spherical and ballistic buttons. The machine is
Machine cost
4
mounted in a box fitted with wheels and
handles for easy set up. It is mainly for threaded button bits, but small downthe-hole bits can be ground in this machine. A steel spring is mounted in
3 2
Annual grinding volume – buttons
1 0
Figures on the left side of the diagram 5 0 0 0
1 0 0 0 0
2 5 0 0 0
5 0 0 0 0
7 5 0 0 0
1 0 0
show cost per button in SEK.
the profile of the grinding wheel, where it functions as a centring centr ing device, allowing for easy grinding. Grind Matic Manual B-DTH is simi-
0 0 0
Cost of grinding reduces dramatically with volume.
When a bit has a heavy wear flat it tends to deviate, and, by the time it reaches the bottom of the hole, it will have
lar to the Grind Matic Manual B. It is
Grinding machines Two parameters guide the selection of
deviated far more than planned. As a result, the blast will produce coarse fragmentation, and much secondary
the right grinding gri nding machine: the number
blasting may be required.
ary. Several Several kinds ki nds of grinding machines are available to satisfy these parameters.
In slope hole drilling, it is of utmost importance that the t he holes are straight. If the holes deviate, the slope walls will
be uneven, making rock reinforcement more difficult than expected.
Rock formations with different di fferent layers and joints are often characterized by heavy hole deviation, putting extra stress on the remaining rock tools in the drillstring. A sharp bit always cuts better, and will prevent both deviation, and its disadvantages. d isadvantages.
of bits to be ground; and whether the machine should be portable or stationIn most cases, a simple machine will suffice for a small operation, grinding only a few bits. The semi-automatic machines are more suitable for larger operations, such as mines and construction sites, where the machine can be stationary, and the rocktools can be brought to it.
Grind Matic HG is a water or aircooled handheld machine for grinding cups. Both spherical and ballistic cups
Diamond grinding wheels.
PRODUCTION DRILLING IN UNDERGROUND MINING
mainly intended for in-the-hole bits, but can also be used for threaded bits with a special bit holder. holder. As an optional accessory, the machine can be equipped with a belt grinder for gauge grinding.
Grind Matic BQ2 is the latest semiautomatic machine, with many features such as auto-indexing device, timer con-
trol, automatic feed, and an automatic centring arm.
These features, coupled to an ergonomic design, ensure high productivity, productivity,
and the machine is designed to handle large volumes of threaded button bits. Cooling water is recycled after the waste product has been separated in a container.
Grind Matic BQ2-DTH is the latest grinding machine for mainly downthe-hole and Coprod bits. It can also
Grind Matic Manual B.
43
TALKING TECHNICALL TECHNIC ALLYY
Grind Matic Manual B -DTH.
be used for threaded bits with a special
bit holder. holder. The machine machi ne has the same sa me features as Grind Matic BQ2, and can grind bits up to 7 in diameter. Comparison of grinding wheel with grinding c up.
Grind Matic BQ2-DTH.
Grinding advice
and the diamond grinding wheel rotate.
The Grind Matic machine’s secret of success is that both the grinding table
surfaces, regardless of whether the buttons are spherical or ballistic.
The result is perfectly ground button In addition, t he machine’s machine’s unique diamond grinding wheel is designed to ensure even wear on its grinding surface, while still retaining its profile.
This, in tur n, guarantees the button shape throughout the life of the wheel.
Secoroc’s advice is to use Grind Matic grinding machines, with profiled
diamond grinding wheels, for grinding button bits. It is the only solution able to consistently deliver perfectly shaped buttons on customers customers’’ bits.
Correct grinding is important for every drilling operation, particularly in these days of cost consciousness and fierce competition. It can make a world of difference to the bottom line.
Bo Persson
44
PRODUCTION DRILLING IN UNDERGROUND MINING
EL AGUILAR, ARGENTINA
Explo xplorin ringg the potential of El Aguilar Keeping in touch In the remote mountain range of northern Argentina, the El Aguilar mine is being equipped with modern technology to meet ambitious goals. Located 4,300 m above sea level, and surrounded by desert and mountains, the mine is remote and difficult to reach. However, to run the country’s try’ s most important under ground zinc, lead and silver mine, El Aguilar management keeps well in touch with the benefits of new technology.
Pioneers The mine, which lies in the eastern slope of El Aguilar mountains, is owned by Co Compa mpa ñí a Mi ne ra Ag ui la r S. S.A. A. (CMA), which also owns Sulfacid S.A., a refinery pioneer in the sulphuric acid and electrolytic zinc industry. industry. Here, in this isolated but unique mining community of about 4,000 people, 350 work in the mine in three, 8 hour shifts per day. Production currently runs at 38,000 t/ month, and the mine’s short term goal is to increase this to 48,000 t/month. Operations are widely dispersed over a large area, and several fronts are worked simultaneously. Therefore, all equipment has to be used as efficiently as possible. The Aguilar orebody has great potential. tentia l. Even though it has been mined for more than 70 years, new sectors are now being discovered. Further more, the company has significantly changed its strategy in recent years with regard to the equipment it needs, and also i n terms of greater emphasis on exploration. In order to reach its goals, CMA employs a fleet of eight Atlas Copco Boomer 104 and Boomer 281 drill rigs, r igs, one Boltec 235 bolting rig, one Simba 157 production drilling rig, nine Scooptram loaders ST6C, EST 3.5, ST710 and ST2G,
The El Aguilar mine is located at 4,30 0 m above sea level and surrounded by mountains and deserts.
and three core drilling rigs Diamec U6, Diamec 252 and Diamec 262. Many of these products have been acquired with the assistance of longterm financing arrangements provided by Atlas Copco Custome r Finance that have been consistently offered despite a difficult economic situation within the country.
Exploration and development The CMA mine is divided into three main sectors, according to the degree of mechanization employed and the grade of the ore. These are Pique Inferior, which is the deepest at level 31; Mina Esperanza; and Nueva Norte, which is in itself divided into two parts, Mina Rincón and Mina Oriental. In Pique
PRODUCTION DRILLING IN UNDERGROUND MINING
Inferior, the aim is to go deeper and a nd a new raise has increased mineral resources. Mina Esperanza has been accessed via the lower drift on the third level as the higher levels are gradually exhausted. Given the shape of the orebody, which has a dip of more than 50 degrees, the entire operation will use only cutand-fill or long hole stoping methods. The Boomer 104 is used for face drildr illing, while the Simba 157 is used in production to drill the 18 m high stopes. For safety reasons, the LHDs are operated by remote control. In Nueva Norte, particularly in Mina Oriental, the miners are only a few metres from the orebody and an 89 m deep ventilation shaft has been raise bored. In this section, the main mining mini ng method is cut-and-fill. In faces of cross-section 4.5 m by 4.5 m they drill around 50 holes
45
EXPLORING THE POTENTIAL OF EL AGUILAR
The Simba H157 at work.
45 mm diameter and a nd 14 ft long. At present, El Aguilar is 95 percent mechanized and several of the latest methods of excavation are being employed, some developed on site. These methods i n-clude n-clude:: room and pillar with bench and fill; conventional cut-and-fill; cut-and-fill with horizontal
and vertical chambers using long hole drilling, and muck-ing out with remote control vehicles and other variants; sublevel stoping, underground vertical/ sub-vertical benching; and exploration methods for deep levels. In December, 2004 a shaft was constructed in Mina Esperanza exclusively
Typical drill patterns at El Aguilar.
CABLEBOLT DRILLING Rows of 5 holes every 1.5 m
�
46
Pillar of the community On the surface, the El Aguilar mine provides provid es for the well-being well-being of of the whole whole community. The town relies completely on the company for its fresh water and electricity supplies, as well as for its well-equipped 40-bed hospital, its schools, schoo ls, stores, churches, sports and cultural and other facilities. A private transport company provides transportation between the mine and the nearest densely populated cities of La Quiaca and San Salvador de Jujuy. The company is not just a business, it also has a strong social responsibility. responsibility.
Acknowledgements
�
PRODUCTION DRILLING Rows of 7 holes every 1.5 m
to generate ventilation from the tunnel to level 577, the equivalent of 110-115 m. With this new method, all the air enters enter s via the tunnel, flows through the entire sector, and is extracted via the shaft. In addition, an exhaust fan was placed in the entrance of the mine to extract the air and distribute it to different underground sectors. The installation of a ventilation shaft in Pique Inferior will allow fresh air to enter the lower levels. El Aguilar has one of the world’s highest proportions of support elements in relation to tonnage produced, which indicates the complexity of the orebody orebody.. The ground is very varied, irregular, and dominated by fractures or faults. In addition, El Aguilar has devised an advanced ground control method which has served as a model for operations in remote places around the world. The drifts generally have roofs of very poor quality rock with consistent faults, although the floors are generally of good quality. This makes it necessary to employ a range of bolting techniques tech niques for different types of rock bolts, f rom short bolts such as split-set or Swellex, and cement grouted rebar. Cable bolting with the Boltec 235H, shotcreting, and steel arches are also used to good effect.
1 1
5 7
Atlas Copco is grateful to the management at El Aguilar for its assistance in the preparation of this article. This article frst appeared in Atlas Copco Mining & Construction magazine No 2 2005.
PRODUCTION DRILLING IN UNDERGROUND MINING
NEW SOUTH WALES, AUSTRALIA
Increasing drilling rates at Ridgeway Big output A determination to benefit from drill rig automation technology can be seen in practice at Newcrest Mining’s Mining’ s Ridgeway gold-copper operation, a mine that has already produced impressive performances in terms of profitability and production. The mine is one of Australia’s largest underground mines with a total ore production of 5.6 million t/y. Located near Orange in Central New South Wales, near the well-known Cadia Hill open pit mine, Ridgeway has only been in operation since 2002. In April, 2005 the mine switched from contractor to owner mining. Looking to further increase the productivity of their two Atlas Copco Simba L6 C longhole production drill rigs, the management has introduced a higher level of automation, resulting in improved drilling rates with the same manning and equipment.
Sub level caving The Ridgeway deposit, discovered in 1996, 19 96, lies 500 m below the sur face and is accessed by a decline. Extraction of the gold-copper ore began in 2002, and in 2004 the mine produced al most 450,000 ounces of gold and 45,000 t of copper. Production is by sub level caving, commencing at the top of the orebody, with extraction levels at 25 m vertical intervals. Today, 5.6 5.6 million t /y of material materia l is mined, and Ridgeway is recognized as one of the most efficient gold producers in operation, with sufficient mineable ore reserves to last until 2018. Having successfully used singlehole automation for several years to drill during during shift changes a nd breaks, Atlas Copc Copco’ o’ss Advanced Boom Control (ABC) fan automation technology was selected to further enha nce this capa bilit y. Ridgeway has two Atlas Copco Simba L6 C production rigs continuously employed employed on d rilli ng upholes, one of which is currently fitted with w ith the
Atlas Copco Simba L6 C production rig fitted with ABC Total for com puterized operation.
ABC system, an automation technology that is well-suited to the application. However, Howev er, a low-cost option was required to deliver extra drilli ng capacity, and the management decided that ABC Total had the potential to give a productivity improvement of up to 10%. As a result, the first Simba was equip ped with ABC Total Total for appraisal, and then the second Simba was automated and fully functional by March, 2006.
Fully automated The ABC Total version of the Atlas Copco technology employed at the Ridgeway mine fully automates the drill ing process. The boom and feed are positioned automatically according to a pre-programmed drill pattern and drilli ng sequence. Automatic collaring, rod changing and drilling of each hole in the sequence are then carried
PRODUCTION DRILLING IN UNDERGROUND MINING
out without direc t involvement of the operator. The need to manually change bits during the drilling dr illing of some long holes, holes, or between holes, had been a major hurdle for the the mine to overcome in its d rive to fully automate production and development drilling processes. This is the first time that a mine in Australia has used a mechanized bit changing system in conjunction with the rig automation technology te chnology.. The bit carousel carou sel rotates, rotates, allowing dr ill bit s to be re moved a nd re placed without operator intervention. This process is activated by the Atlas Copco Rig Control System, RCS, which which is a n integral par t of the automation package.
Continuous drilling Ridgeway’s use of the ABC and bit changing chang ing systems marked a significant
47
INCREASING DRILLING RATES AT RIDGEWAY
How the bit changer works A
Figure 1. All the rods from the drill string are moved over to t he magazine of the Simba (see insert, left). The rock drill advances to the drill steel support (A) to collect the worn bit on its shank adapter. The rock drill then moves backwards to the bit changing position. The drill bit cassette swings in to collect the bit.
Drill steel support
Rod magazine Bit cassette
The Simba bit changer allows drill bits to be removed and replaced automatically.
point in the adoption adopt ion of such advance automation technology technology by the mining industry in general general.. Aut omation and associated performance monitoring and control technology
are the key to harnessing all the power that can be generated with modern rock drills. While RCS technology is well esta blished, blis hed, the recent r ecent ly developed develop ed Atl as Copco bit changing system opens t he door to full automation of continuous drilling sequences and processes for many mines. Current drill ing technology is so advanced, with electronic systems able to monitor, measure and relay thousands of bytes of performance performance data per minute, that adjustments can only be made by a computerized control system.
48
B
Figure 2. The worn bit is unthreaded from the shank adapter and retained in the rotating cassette by a locking arm (B). T he rock drill then moves backwards.
Rock Drill
The next ste p at Ridgeway would be to ta ke adv advant ant age of Ethe E the rn rnet et,, o r even wireless communications technology, nolo gy, in order to download dril l plans pla ns fr from om m ine pla plann nn ing off ice icess t o drilling equipment, and transfer production data back to the main com puter. put er. The ope rat or would be able a ble to see how accurately he has been drilling, and make any necessary adjustments almost immediately.
Acknowledgements This article frst appeared in Atlas Copco Mining Min ing & Co Const nstruc ructio tion n mag magazi azine ne No 1 2006.
Figure 3. The cassette rotates to align the new bit with the rock drill. The rock drill then moves forward to collect the new bit. The drill bit cassette swings aside, allowing the rock drill to move forward and place the new drill bit into the drill steel support. The first drill rod is then loaded from the rod magazine and drilling can begin again
PRODUCTION DRILLING IN UNDERGROUND MINING
CAMPO FORMOSO, BRAZIL
Sub level caving for chromite In search of excellence Cia de Ferro Ligas da Bahia (Ferbasa) is a private c apital group, which produces chromite, silicon and limestone. One of Brazil’s most important metallurgical companies, Ferbasa has surface and underground mining operations in the state of Bahia in north-eastern Brazil, where their Pedrinhas open pit chrome mine, located in Campo Formoso, has been in operation since 1961. Pedrinhas currently produces about 2,400,000 cu m/year of chromite ore and waste, yielding 54,000 t/year of hard lump chromite and 114,000 t/year of chromite concentrate. At the Medrado and Ipueira underground mines, lump chromite is produced using primarily sublevel caving techniques with raises opened using slot drilling, where a fleet of Atlas Copco equipment offers key support in exploration, development development and production.
Entrance to the Ipueira mine.
of run-of-mine ore for a final production of 127,000 t of hard lump. In the same year Medrado produced 192,000 t
of ROM ore for a final production of 48,000 t of hard lump. Current target is a total of 216,000 t of hard lump.
Underground geology Located in the city of Andorinha, a round
Underground exploration
100 km from the Pedrinhas mine, m ine, the
The company is always looking for the
company’ss underground company’ undergr ound operations have
best way of doing things in consultation with workers, technical consultants and through visits to other mines. The consultation process also includes manufacturers of mining mi ning equipment, with which Ferbasa discusses the best technological
been developed within the Medrado/ Ipueira deposit. This is one of several chromite-mineralized intrusions in the Jacurici Valley
in the north-east of the São Francisco Craton, which hosts Brazil’s largest chromite deposits. Being irregular and
options for its operations. This consultation process is very important for the
an operator’s operator’s panel. This machine is used in all situations at the underground mine, to drill holes of up to 150 m deep.
The decision to acquire this machine took into account the fact that it is equipped with a wire li ne system. This feature makes possible to conduct core drilling in the worst rock conditions, such as the faulted and fractu red rock at Ferbasa.
Ferbasa carries out about 7,200 7,200 m/y m /y of drift devel development. opment. The fleet of deve-
lopment rigs includes two Atlas Copco face drilling rigs. One is a Boomer 252
rig equipped with COP 1238 rock rock drill dril l which drills 3.9 m long holes to achieve
6,000 drilled metres/month at a productivity of 55 m/hour. There is also a
fractured with numerous faults, the deposit presents a considerable geological geological and mining challenge.
mine, in order to help maintain a high
The Medrado/Ipueira deposit is divided into several mining areas. There are the Medrado mine and the Ipueira
Medrado/Ipueira orebody represents a challenge. With an average thickness of 8 m, and 500 m long panels, the orebody
m/hour.
mine, the latter of which is divided into
is irregular and fractured with numerous faults. The accurate delineation of the orebody is very important, and to this end the geology department has to carry out a great deal of exploration
Sublevel caving
drilling. The main machine employed in this key task is an Atlas Copco Diamec
in some areas of Ipueira, depending on the layout of the orebody. When the orebody is vertical, sublevel caving is used
five working areas: Ipueira II, III, IV, V and VI. Currently, besides Medrado, Medrado, only Ipueira II, III, IV and V are opera-
tional, whereas Ipueira VI is a future expansion project. project. The underground mim ines have have been in steady operation ope ration since 1977.. In 2004, 1977 2 004, Ipueira produced 450,000 t
level of moder nization. level From a geological point of view, the
U6 exploration drill rig equipped with
PRODUCTION DRILLING IN UNDERGROUND MINING
Rocket Boomer M2 D rig equipped with COP 1838ME rock drill which drills 4.5
m long holes to achieve achieve 12,000 drilled dri lled metres/month at an average rate of 70
The main underground mining method
employed is longitudinal sublevel caemployed ving, though open stoping is also used
49
SUB LEVEL CAVING FOR CHROMITE
Production loading
N 55
n o i t c u d o r P
Charging – production holes
N 65
Production drilling
N 75
Mucking out
N 85
Charging
N 95
t n e m p o l e v e D
Scaling
N 105
Drilling
N 115
Shot creting
N 125
Layout of Ipueira mine.
and, in the t he few cases when the orebody
of the orebody. The vertical distance
blast holes, which have a diameter of
is horizontal, open stoping is the preferred method. Both methods are safe, with currently acceptable dilutions. However, the management has started
between sublevels sublevels var ies from 14 m t o
51 mm and a burden of 2.2 m. At the same time, they are studying st udying the pos-
looking for suitable alternative methods
the production levels to the surface
that will reduce the dilution di lution in future.
using rigid frame trucks. In terms of production, the company
For longitudinal sublevel caving, production drifts a re developed developed in the footwall
30 m. Production drilling is upwards, using a fan pattern. The broken ore is loaded using LHDs, and is hauled from fr om
drills 180,000 m/year of production
sibility of changing to 76 mm diameter holes hol es and 2.8 m burden, in order to reduce costs.
The fleet of production drill rigs includes an Atlas Copco Simba 254 and a Simba 253, both electro-hydraulic
The locations of drifts and d rill patterns are adapted to the ore-waste boundaries.
Blast holes
Ore e l b a C
Waste
Drift 2.2 m
50
PRODUCTION DRILLING IN UNDERGROUND MINING
SUB LEVEL CAVING FOR CHROMITE
Slot drilling at Ferbasa: the Simba M6 C-ITH in action and right the perfectly finished row of holes.
rigs equipped with COP 1238ME 1238ME rock drills, which drill 6,000 m/month to achieve a productivity of 22 m/h. The mine also has a Promec M195 pneumatic rig equipped with COP 131EL rock drill. These drill rigs are also used to drill orebody definition holes, and achieve 3,500 m/month.
Slot drilling One of the main challenges at Ferbasa Ferbasa’’s underground operations is t he developdevelopment of inverse drop raises. These openings, which are also called ca lled ‘blind raises’
advances of up to 6 m. Nowadays, this
of up to 25 m in length length are succes successful sfully ly
practice has been replaced with a fully
achieved. The main advantages of the
mechanized method, increasing the speed and safety of drilling the open-
method are personnel safety and speed
ings. Looking for a solution to improve operator safety when drilling these production ductio n raises, technical personnel from
Ferbasa visited LKAB’s Malmberget iron ore mine in Sweden, where they studied the development of inverse drop
raises blasted in one single shot. After the visit, Ferbasa star ted employing a
in the dri lling. Also, slot slot drill ing is more precise and, in general, more productive.
A Simba M6 C-ITH drill rig equipped with COP 64 ITH hammer and ABC
Regular system, as well as an on-board booster compressor, has been acquired for drilling inverse drop raises with holes up to 10 in diameter. Depending on
slot drilling technique, and Ipueira and Medrado are now the most experienced
the length of the raise, and the quality of the rock mass, the slot drilling tech-
mines in Brazil in its use. Slot drilling
nique is used. If the length of the raise is short, and the rock quality poor, the traditional trad itional techniqu techniquee with reamed holes holes is used.
because they don’t communicate with the upper level, can only be accessed from the lower level. level. This limitation is
requires a row of 190 190 mm diameter diamet er interint er-
dictated by the mining methods. Previously these blind raises were developed upwards by successive individual
drill hammer. Thus, with an available free face, drilling accuracy, and controlled blasting techniques, openings
connected holes to be drilled using a special guide mounted on a regular ITH
The slot drilling crew with their Simba M6 C-ITH.
Until the Simba M6 C-ITH arrived, ar rived, Ferbasa was carrying out slot drilli ng with only one machine. They chose the
new Simba rig because of its advanced technological and safety features. One of the main advantages is the setup, which
only has to be carried out once at each site. The Simba M6 C-ITH drill rig is also
easy to operate, and the spacious, airconditioned cabin is an attractive feature. The mine spent five years looking for a solution to the opening of inverse i nverse drop
raises, and is pleased with its investment in technology and modernization represented by the Simba M6 C-ITH.
Acknowledgements The managements at both Ipueira and Medra do m ines are Medrado a re thanked thank ed for their contributions to this article, which first appeared appe ared in Atlas Atla s Copco Mining Min ing & Construction Magazine No 3 2005.
PRODUCTION DRILLING IN UNDERGROUND MINING
51
Atlas Copco Cabletec LC.
52
PRODUCTION DRILLING IN UNDERGROUND MINING
MICHILLA, CHILE
First Cabletec cable bolting rig in South Americ Americaa Winning in Michilla Cable bolting and grouting operations have have been greatly speeded up at the Michilla C opper Mi ne in Chile with the introduction of an Atlas Copco Copc o Cabletec cable bolting rig, the first of it s genre to be deployed in South America. Indeed, the cables necessary for securing the production stopes at Michilla are now installed 15 times faster than they were previou sly. This has released manpower for other work, and improved the overall efficiency of the mining op eration. Above all, the Michill a experience is a grea t reference for this new concep t machine, which is set to revolutionize cable bolt installation underground.
Successful operation The Cabletec has been successfully operating for a year in Antofagasta Minerals’ Michilla copper mine in Chile, some 750 km north of Santiago. The main mining method at Michilla is cut-and-fill using a drift and pillar layout in which mining progresses upwards. The production drifts are 7 m x 5 m and the pillars are 7 m x 7 m. Some sub level stoping is also used. Systematic cable bolting is required to ensure safety while other rigs are d rilling production holes upwards through the orebody. A total of 100,000 m/y of cable bolts are needed for all the underground operations. During Duri ng its first year at Michilla, the Cabletec has shown very positive positi ve results. Its cable installation ca pacity is some 50% better than alternative mechanized solutions. It gives a safe and greatly improved working environment, with all operations controlled from the silenced, air-conditioned cab.
Two booms The Cabletec is unique, in that it is a twin boom machine. Positioning and
Drilling and cable installation are carried out simultaneously by separate booms on the Cabl etec.
feeding of the grouting hose and cable into the pre-drilled hole is undertaken using one boom, while the other boom is used to drill d rill the t he next bolt hole. hole. Both operations can be carried out simultaneously, greatly reducing cycle time and increasing f unctionality unctionality.. Because drilling and cable installation are ca rried out by separate booms, there is no risk of cement soiling the drill unit, or splattering components, significantly reducing maintenance costs compared to other mechanized methods.
PRODUCTION DRILLING IN UNDERGROUND MINING
Superior productivity Prior to the arrival ar rival of the Cabletec, cables cables were installed manually, each taking about 105 minutes to grout and install. Today, the Cabletec does it in only 7 minutes, with less interference and using fewer operators, saving valuable time and greatly improving the efficiency of the production operation. The total cost of rock reinforcement is historically USD1.8/t of ore. However, Michilla management estimates that, thanks to
53
CABLETEC CABLE BOLTER IN SOUTH AMERICA
Cabletec is a fully mechanized cable bolting rig with the Ri g Control System, RCS, for high productivity and precision.
the speed of the Cabletec, about 20% of this cost is being saved. The drilling boom on the Cabletec in Michilla is equipped with a COP 1838 1838 rock drill and a rod-handling carousel with a capacity of 17+1 Speedrods. These are each 1.8 m long, facilitating
hole depths of up to 32.4 m and today they use 63.5 mm drill bits. The 1,700 kg capacity cable cassette at the rear of the rig is ea sy to refill, thanks t o its unique fold-out design. The onboard silo has a capacity of 1,000 kg of dry cement, and auto-
At Michilla four parallel holes are drilled for bolting in eac h row in the 7 m wide production drifts.
matic mixing is to a predetermined formula, resulting in a smooth grouting process. For face drilling, Michilla Michilla has Boomer Boomer M2 C drill r igs, as well a s Boomer 127 and 282 rigs equipped with 14 ft rods, for an effective pull of 3.7-3.8 m. ANFO is the bulk explosive used. About About 800 800 m/month of d rif t is developed and 110,000 110,000 t/month of rock is mined, of which 40,000 t is waste. Michilla is operating at depths of below 600 m, and produced 46,000 t of fine fi ne copper in 2005. 2005. Resources are expected to last until 2012, after which production will shift from underground to surface operations.
Acknowledgements The management at Michilla are thanked for their their assist assistanc ancee in the prepar preparati ation on of this article which frst appeared in Atlas Copco Mining & Construction magazine No 1 2006 2006..
54
PRODUCTION DRILLING IN UNDERGROUND MINING
GARPENBERG, SWEDEN
Innovative mining at Garpenberg Garpenberg
Lina shaft
0Z
Garpenberg North
Gruvsjö shaft Capaci Cap acity: ty: 450 450 000 000 tpa
Smälta Smä ltarmo rmosse ssen n
Shaft Capacity: 850 000 tpa
Dammsjön
0Z
Dammsjö Agmin ?
Lappberget
?
400 Z
400 Z
500-785 Z
Finnhyttan
500800 Z
Tyskgården 7001000 Z
800 Z
Gransjön Kaspersbo 910 10 Z
Kanal Ore Strand Ore Potential
925-1100 Z
?
Dammsjön Dammsjö n Kvarnb Kvarnberget erget
1200 Z
1600 Y
20 00 Y
800 Z
870 Z
2400 Y
2800 Y
320 0 Y
1000-1300 Z
11001400 Z
3600 Y
40 00 Y
440 0 Y
1200 Z
4800 Y
5200 Y
Production levels Potential areas outside ore reserves 2005-01
One million tonnes of ore
Idealized long section at Garpenberg showing all orebodies and shafts.
The Garpenberg mine, located 200 km northwest of Stockholm, extracts more than 1 million t/y of ore. The ore is polymetallic and contains mainly zinc, silver and also some lead, copper and gold. Additionally, about 500,000 t of development waste is excavated annually. Over recent years, Garpenberg has been forced to add reserves, or reconsider its future. Happily, more orebodies have been discovered, and new stoping methods and drilling technology introduced.. Atlas Copco has cointroduced operated closely with Garpenberg management to resolve technical issues, designing and supplying equipment to suit the evolving objectives. As a result, the mine achieved its Mt of ore in 2005, at very acceptable grades.
adjacent concentrator. Boliden acquired
AB Zinkgruvor Zin kgruvor developed developed a new main shaft and concrete headframe and the the mine in 1957 and completed the development of a second shaft in 1972, accessing the 800 m level at Garpenberg
North, having a hoisting capac ity of 850,000 t/y and effectively creating a second and larger mine.
5-6 m thick slices drilled dril led horizontally from 50-300 m long and up to 15 m wide stopes. Rock fill was used in the bottom cut, and either plain sand or cemented hydraulic fil l above. The sand comes from the coarse fraction of
the mill tailings, and the fill is supplemented by development waste. Mining starts normally at the centre
pany located another orebody under the
of the base level of the stope and progresses towards the ends and upwards.
Dammsjön and, in the 1980s, consid-
The last cut, just below the crown pillar,
ered draining draini ng the lake in order to develop develop an open pit. The mineralization in the Garpenberg area occurs in a long, narrow syn-
is heavily reinforced to facilitate the
Between these two shafts, the com-
clinal structure which is believed to be Middle Precambrian, but may have been
recovery of the 8-15 m high pillar using up holes drilling and blasting.
The undercut-and-fill method, progressing downwards, was used in the
remobilized later. The orebodies are
Strandgruvan section from the mid-70s until 2001, when the ore was mined out.
vertically extensive extensive lenses that are a re usually nar row row,, much folded and therefore twisting and irregular.
This method provided a safe working roof in the weak, fractured ore with unstable footwall, for just the extra cost of cement and rebar reinforcement.
History
Cut and fill
Mining has been conducted at Garpenberg since the 13th century. The present
Until very recently all of the ore, subdivided in 100 m-high slices, sl ices, was extracted by cut-and-fill mining, taking
operations sta rted in 1950-53, 1950-53, when
PRODUCTION DRILLING IN UNDERGROUND MINING
The method was suited to the orebody irregularities, and no crown pillar had to be left or recovered. The introduction of trackless mining and further exploration expl oration of the mineralization mineral ization in the
55
INNOVATIVE INNOVA TIVE MINING AT GARPENBERG
drilling at the t he 800 m and a nd 1,000 m levels levels
in Lappberget, and by February, 2003 was able to start mining ore from the new source. Zinc concentrate production in the year increased to 80, 80,748 748 t. In March, 2004 the connecting drift
was completed, and the formerl formerlyy separate mines have since been regarded and managed as a single operation. The drift
allows access and infrastructure development of new mineable areas, and Garpenberg quickly boosted mine output. The main focus has been be en on Lappberget, including driving a ramp close to the orebody from the 350 m level, level, with connecconnec -
tion to the surface sur face scheduled for 2007. 2007. The Tyskgården mineralization, discov-
ered in the early 1980s, 1980s, also became accessible, and mining started there in 2003-4. In 2004 Boliden discovered an extension extensi on of the Dammsjön mineralizamineraliz ation around the 800 m level, level, and during duri ng
2005 a new discovery was made, the reportedly large and potentially h ighSimba M7 C production drill rig at Garpenberg.
Garpenberg North mine led to the pro-
gressive extension of a 1:7 ramp down to the 910 m level. In 1998-99, it was extended to the 1,000 m level, increasing the overall length to 8.7 km.
To increase hoisting capacity at the Garpenberg mine, the new Gruvsjö pro-
duction shaft was completed in 1997 and the original shaft was converted for personnel and materials hoisting. With a hoisting capacity of 450,000 t/y, the newer shaft connects with a ramp accessing the Kanal and Strand orebodies.
The present operating area a rea extends approximately 4.5 km SW to NE from the original shaft to the Gransjön mi-
grade Kvarnberget deposit.
While the new shaft raised hoisting capacity, and ramp extension accessed
Higher output
new ore in the North mine, metals pro-
In 2005, the mine mi ne produced 1,102,000 1,102,000 t ore grading 5.75% Zn, 2.28% Pb, 0.09% Cu and 117 g/t Ag. Approximately 40%
duction rose to record re cord levels in 1998. However, this improvement could not 2001, despite a rise in ore production. And proven plus probable ore reserves
of the ore came from Lappberget. The mill yielded 101,000 t of 55.3% zinc concentrate; 29,000 t of 72% lead concentrate with 1,800 g/t silver; 2,800 t
declined from 5.7 Mt in 1998 to 2.2 Mt
of 15% copper concentrate concentrate with 40,000 4 0,000
at 4.0% Zn in 2003, 20 03, putting a question
g/t; and 120 t of precious metal concentrate grading 65% lead, 40,000 g/t silver and 400 g/t gold. Some 967,000 t of tailings retained 0.34% Zn, 0.29% Pb, 0.02% Cu and 25.5 g/t Ag. By
be maintained. Zinc concentrate output fell from 69,051 t in 1998 to 61,126 t in
mark on the future of the mine. However, Boliden continued to make
investments in technology for the long term at Garpenberg. The mine, the company and the market are a re now benefiting. And the geologists are very popular.
ning section.
Concentrate productio production n Upgraded in the early 1990s, the concentrator yields separate zinc, lead, copper and precious metals concentrates. The zinc and a nd lead concentrates are trucked to Gävle harbour and shipped either to Kokkola in Finland or Odda in Norway. Norway. Copper and a nd precious metals concentrates are railed to the Rönnskär smelter in Sweden. Since 1957, Boliden has milled over 20 million tonnes of ore at Garpenberg.
56
end-2005 Boliden employed 280 people
at Garpenberg, with a further 70 working for contractors at the site.
New reserves Probably the most significant event at Garpenberg during the period of decline was the discovery in 1998 of a new ore-
body between Garpenberg North and Dammsjön, named Lappberget. This encouraged the company to start development in 2000 of an a n approximately 3.0 km long drift to connect the 900 m level at Garpenberg North, first to Lappberget for exploration exploration access, and a nd thence to the ramp at the 800 m level at Garpenberg. During 2001, 2001, Boliden started core
The operation works around the clock 7 days/week in both the concentrator and the mine, with mining carried out by four production teams supported by a development crew and a charging crew. Garpenberg is t he Hedemora Community’s largest private sector employer.
Since the beginning of 2005 exploration has continued, not only adding tonnes,
but also raising average grade. Thanks to the exploration effort, Garpenberg also started start ed 2006 with proven reserves reserves of 4.73 4.73 Mt grading gra ding 6.0% Zn, 2.5% Pb,
PRODUCTION DRILLING IN UNDERGROUND MINING
INNOVATIVE INNOVA TIVE MINING AT GARPENBERG
0.1% Cu, 99 g/t Ag and 0.3 g/t Au. Probable ore brought total reserves up to 10.67 Mt. That compares with 3.63 Mt of reserves at the beginning of 2005. Total resources were also increased, from 11.08 Mt in January, 2005 to 13.22 Mt. This should be sufficient to add another 15-20 years to mine life.
896 Z
1
Mined in “Central Zone”
1
3m
916 Z
These quantities should increase further when portions of the t he orebodies at Kaspersbo (from 1,000 m down to
Possible sequence
3
9
4
10
5
11 6
1,300 m), Lappberget (500–800 m and 1,100–1,400 1, 100–1,400 m), Dammsjön Da mmsjön (500–785 m and 925–1,100 m), and a smaller sec -
956 Z
tion at Tyskgården are included in the reserves figures. Kvarnberget is yet to
17.5 m Drawpoint spacing
be added, and Boliden is also exploring exploring
Primary stope: 15 m wide x 40 m high Paste fill
Note: Not N ote e:
Secondary stope: 20 m wide x 40 m high Rock fill
How H ow this hole must be designed to just miss iss the drift below to break properly
to the north of the Gransjön where the
8
property extends for several kilometres.
4 996 Z
Sublevel stoping at Lappberget The geological and geotechnical char-
Sublevel stoping layout and mining sequence for Lappberget orebody.
acteristics of significant portions of the
newly-discovered orebodies allow newly-discovered a llow mining using more productive longhole methods instead of cut-and-fill. Lapp-
billion for developing Lappberget. The
is relatively small, small, and a nd large quantities
overall ov erall programme includes: increasing
berget ore, for instance, can be up to 60 m
designing and building a paste fill pro-
of development development muck have to be accoma ccommodated underground as hoisting facilities are used for ore only.
wide through considerable vertical distances, and has proved to be suitable for sub-level stoping using a system of
duction/distribution system; and start-
primary and secondary stopes progressprogressing upwards.
concentrator capacity t o 1.2 Mt/y;
in Lappberget.
The method can be described as a modified suble sublevel vel stoping with successivee back fill siv fil l as mining is progressin progressing. g. The 10 m wide cut-off cut-off slots are drilled dril led across the orebody using up-holes and
Rill mining
blasted in one single firing, starting from the centre. Seven 127 mm holes are left
ing longhole longhole drilling. drilli ng. This latter project
involved rill mining in the Tyskgården orebody, followed followed by subleve sublevell stoping st oping
Primary stopes are 15 m wide and 40 m high a nd filled with paste made
from concentrator tailings mixed with about 5% cement. The 20 m wide secondary stopes are filled with development muck without cement. High precision precisi on drilling is necessary to get optimum ore recovery and fragmenta-
A special mining method known as rill mining has been developed for excavating excavating
the Tyskgården orebody. orebody. The orebody
uncharged to provide sufficient expansion for the remaining 64 mm holes. After the slot has been opened, 70 degrees up-holes fans consisting of eight,
Development and primary stoping layout 1080 level.
tion. This mining min ing method can possibly be used in par ts of the Kaspersbo orebody, if rock quality is high enough. This will
help with cost control, which is crucial for mining in Sweden. With Lappberget alone containing 5.46 Mt of the current reserves, grading over 7% zinc and 2.6% 2 .6%
lead, plus silver and gold, it is no surprise that present development activities
focus on using longhole-based production from these orebodies to raise total metal-in-concentrate output. Presently eight orebodies are being exploited. Garpenberg has generated a strategic plan for 2006–2019 allocating SEK 1 PRODUCTION DRILLING IN UNDERGROUND MINING
57
INNOVATIVE INNOVA TIVE MINING AT GARPENBERG
Refill of waste One fan Max 2m
Blasted ore t o l s f f o t u C
Waste
8 h o 3 l e s f a n i n s e i n a c h o n f a e b n Ø la s t 7 0 1 . m 8 m m
A p p r o x . 1 5 m
A p p r o x . 1 5 m
70°
45°
Rill mining in progress.
approximately 17 m long, holes are
available, with a limited a mount of
blasted into the void. Three rows having
truck ore haulage to surface possible.
a total of 24 holes are blasted simultaneously.. After neously Aft er mucking out each blast, new waste is discharged into the stope
New drilling technology
forming a 45 degrees rill down into the
And, although flotation capacity has been improved, concentrator throughput is now limited to the same sa me sort of tonnage by grinding mill capacity.
drawpoint. drawpoin t. As the waste material will
Assuming demand for Garpenberg Gar penberg con-
ment to Boliden’s underground mines
stay quite stable at 45 degrees rill angle, the risk of ore dilution is negligible.
centrates increases increases in the near term, it will be necessary for New Boliden to decide whether to i ncrease hoisting
for many years. Recently Recently,, the company
Output limitati limitations ons
capacity. Developing the now-available reserves for higher long-term production using additional hoisting and processing capacity
The total m ine output is restricted to the 1.2-1.3 1.2-1.3 Mt/y hoisting capacity
might double the amount a mount of investment initially planned.
Atlas Copco has supplied drilling equip-
has worked part icularly closely with Garpenberg on the development of computer-based technology for more precise drilling and blasting to enhance productivity and reduce ore dilution and operating costs.
Drill pattern for cut off slot.
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PRODUCTION DRILLING IN UNDERGROUND MINING
INNOVATIVE INNOVA TIVE MINING AT GARPENBERG
This joint devel development opment process started with the 1998-1999 1998-1999 ramp ra mp extension at Garpenberg North. The complex geo-
logy results in winding cross c ross sections of varying width, and ore boundaries which are difficult to predict by core drilling. To enable the drifts in the cut
Reference line
Mine coordinate system
X/Y horizontal Z vertical
and fill stopes to follow the paths of the
orebodies, accurate production maps and precise drill rig navigation are essential. Producing drill plans in t he office is relatively easy. However, get-
Reference point
(x, y, z)
X Y
ting drill plans that match the actual ore boundaries is a challenge challenge,, and frequent fre quent--
ly the dri ller is obliged to i mprov mprovize ize while drilling, drilli ng, which which can lead to poor
Z
blasting results.
Drill plan generator The drill plan generator overcomes the ore navigation problem by assisting the operator to create an optimum drill plan
right at the face. In case the generated
Navigation system for downwards longhole production drilling.
drill plan does not match the actual ore boundaries, the operator can define new
with the COP 1838, as well as the
coordinates to correct the situation. To do this, having aligned the feed to the
Rocket Boomer 352S.
laser beam to define the position of the
Mine navigation
rig, the operator points the drill feeds at the four corners of the face, in line with the geologist’s marks. When all adjustments have been made, the Rig Control System RCS will develop the most efficient round compatible with the new parameters. The generated drill plan
is automatically entered into the Rocket Boomer L2 C ABC standard drill ing system, and the operator can start drilling. While drilling, dr illing, each completed hole
is logged, and, if the Measure While Drilli ng (MWD) option is activated, activated, the drilling drill ing parameters along the hole are recorded. All of the data is logged on the PC card for off-line processing in the Tunnel Manager support program, and is t hen transferred to the mine database. As a result of the Drill Plan Generator and ABC Regular, Garpenberg North increased the size of the production rounds from 400 t to 600 t, reduced drilling time from 5 to 3 h/round, reducing costs of explosives, scaling and rock support and, most important, minimizing ore dilution. Garpenberg now has one Rocket Boomer L2 rig with COP 3038 rock drills and one Rocket Boomer L2 C
The availability of orebodies at Garpen-
Boomer rigs can use the MWD system while face drilling, so the Simba can use Quality Log to record drilling parameters and compare the planned and actual result, allowing allowing holes to be re-d rilled if necessary.
berg suitable for mining mini ng with longhole production drill rigs led to a further collaboration. Having already transfert ransfer-
penberg to optimize economy and productivity when applying applying long hole drilling drilli ng
red RCS technology to the Simba long-
mining methods. The target for for 2007
hole drill rigs, Atlas Copco provided the mine with a Simba M7 C that is additionally addition ally able to use new software for precision longhole drilling. This utilizes Garpenberg’s mine coordinate reference, mapping and planning system in a similar way to the software
is to mine about 600,000 t of ore by cut-
developed for the Rocket Boomer L2 C units. Using a PC card, the Mine Navigation
This new technology will help Gar-
and-fill, 300,000 t by sublevel stoping, 150,000 t by rill m ining and 150,000 t 150,000 by crown pillar removal. removal. Further ahead,
sublevel stoping may contribute 50% sublevel of total mine production. However, at present this mining method is completely new to the mining teams at Garpenberg, and they have just started
the process of getting acquainted with
package can effectively integrate the Simba RCS with the mine coordinate
long hole drilling methods.
reference system, system, allowing al lowing the operator
Acknowledgements
to position the machine at the correct vertical and horizontal coordinates in the drilling drif t for drilling planned longhole longh ole fans in precisely the intended place. Using the drill plan supplied by Microsystem (or, (or, in other mines, the Ore O re
Manager package) to the Rig Control System, the operator can drill to the exact x, y and z positions prescribed for each hole bottom. Just as the Rocket
PRODUCTION DRILLING IN UNDERGROUND MINING
This article is based upon an original report by Kyran Casteel. Atlas Copco is grateful to the mine management at Garpenberg for their assistance with site visits, and in particular to Tom Söderman and Lars Bergkvist for comments and revision. This article first appeared in Atlas Copco Mining & Construction magazine magazine No 3 2006. 20 06.
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INNOVATIVE INNOVA TIVE MINING AT GARPENBERG
Headframe at Garpenberg.
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PRODUCTION DRILLING IN UNDERGROUND MINING
KIRUNA, NORTHERN SWEDEN
Automated long Automated longhol holee drilli drilling ng with with Simba at LKAB Mining of the Kirunavaara orebody
1910 1910 1920 1920 1930 1930 1940 1940 1950 1950 1960 1960
Nivå m
1900
0
Ore beneficiation plant 142
Railway to Narvik port
1965 1965 1970 1970
230 275 320 420
1980 1980 540
1990 1990
Skip hoisting 2000 2000
740 775
Sea level
2005 2005
Skip hoisting
Ore buffer pockets
1045 m Main haulage level
Exploration drift 1060 m
1045
Crusher 1175
1365 m New haulage level 1365
Crusher
Modern methods
Mining of the Kirunavaara orebody over the last century.
LKAB is one of the world’s leading producers of upgraded iron ore for the steel industry. It’s iron ore mines at Kiruna and Malmberget in Northern Sweden are models of modern mining methods, with high levels of automation in rail transport, loading and production drilling. Since 2002, production at Kiruna has increased by 40% , and the number of drill metres required has increased accordingly, approaching 1 million m/y. High capacity drill rigs are a must, and the mine fleet of Atlas Copco Simba rigs for up-hole drilling has been expanded to cater for the huge current longhole drilling demand. Meantime, the requirement for slot drilling has increased at Malmberget, where a new computerized production drill rig is taking the strain.
History at LKAB LKAB is an international inter national high-tech miminerals group, one of the world’s world’s leading produ cer s of upg upgra raded ded ir iron on ore pro ducts for the steel industry, satisfying approximately 4% of the world market, and a growing supplier of industria l minerals products to other sectors The company is wholly owned by the Swedish state, and has more than 3,500
employees. Their two iron employees. i ron ore mines, located above above the Arctic Circle in the far north of Sweden, are mining min ing mostly magnetite using sublevel caving. The crude ore is dumped du mped into underground ore passes for loading onto trucks or trains for hauling to a central crushing plant. The crushed ore is then hoisted to the surface for fur ther processing. processing. Underground dergroun d rail transport i n Kiruna is
PRODUCTION DRILLING IN UNDERGROUND MINING
remote-controlled, as are some other operations, for example, production drilling and loading. This degree of automation enables greater efficiency in process control. During the 1990s, Atlas Copco and LKAB developed a pioneering ful ly automatic autom atic long long hole production dr illi illing ng system using the Atlas Copco Simba W469 drill rigs. These rigs have since drilled about 8 million metres at the Kiruna and Malmberget mines. In 2005, LKAB ordered three new Atlas Copco Simba W6 C, to complement the Simba W469s W469s still in operation. These new Simbas, based on the latest generation computerized drilling technology, have met the expectations of the customer, and now form a base for future automation.
61
AUTOMATED LONGHOLE DRILLING WITH SIMBA AT LKAB
between the 775 m and 1,045 1,045 m levels. The mining rate i n 2007 is planned at 27.2 Mt of crude ore, rising to 29.6 Mt/y by 2009. The Malmberget mine consists of about 20 orebodies, of which ten are cur rently mined. Most of of the deposits are magnetite, but non-magnetic hematite also occurs. The present main level of the Malmberget mine is at a depth of 1,000 1,000 m. T he mining rate in 2007 is planned at 16.5 Mt of crude ore, subsub ject to mini ng approvals, with planned extraction extract ion rates of 17.1 17.1 Mt/y by 201 2012. 2.
Sublevel caving
Front view of Simba W6 C drilling in full fan automatic.
Kiruna and Malmberget The orebody in Kir una is a single, enormous slice of magnetite. It is about 4 km long, has an average width of 80 m, and extends to an estimated depth of
2,000 m. It is inclined at roughly 60 degrees. The main level is located on 1045 level, which is 1,045 m below surface level of the original mountain Kiirunavara. Mining of the orebody takes place
The automatic rod handling system with a capacity of 63 m of lon g holes.
62
Slices of ore are drilled upwards with remote-controlled remo te-controlled production dr illing rigs and these rigs are equipped with fan automation. From the control room, the oper ators (dri llers) operate several several drill rigs out in the production areas via remote control. The rig drills upwards into i nto the ore at 80 degrees f ront inclination, forming fanshaped patterns of holes. There are nominally 10 10 dril l holes in each fan. They are drilled from 15 m to 58 m in length. The holes are straight, so that subsequent charging with explosive and blasti blas ti ng can be done effe cti vely and efficiently. The drilling burden is usually 3 m, but in some pa rts of MalmMalm berget they use burden s of 3.5 m. In 2007, Kiruna is planning to drill 1 million m of production holes to produce approximately 27 Mt, while Malm berget is planning to drill 600,000 m to produce approximately 15 Mt of ore. Of the three Simba production drilling rigs purchased by LKAB in 2005, two are Simba W6 C rigs, designed for optimized production drilling at Kiruna, with Wassara ITH-W100 water hammers for nominally 115 115 mm diameter holes. The third rig, a Simba W6 C Slot, is specially designed to optimize up hole slot slot drilling dril ling at Malmberget, using 165 mm nominal diameter slot drilling equipment and the Wassara W120 ITH hammer. The Simba W6 C Slot rig has the ability to drill production holes holes around the slot, with the added benefit of drilling parallel rings from the same setup with a burden of 500 mm. LKAB demands high productivity, efficiency and accuracy from its mine
PRODUCTION DRILLING IN UNDERGROUND MINING
AUTOMATED LONGHOLE DRILLING WITH SIMBA AT LKAB
production d rill rigs. Automation Automa tion and the ability to remotely control the drill rigs is often an integral part of obtaining the drilling rates required. All LKAB production drill rigs r igs have magazines for sufficient rods or tubes to drill the required production hole lengths. A crane is always available to assist with changing out worn drill tubes and hammers to avoid heavy lifting.
Simba W6 C The Simba W6 C rigs are equipped with a rig control system specially designed for ITH applications. All units are equipped with Rig Remote Access via standard WLAN systems, which ena bles a number of functions such as a s remote supervision when drilling unmanned in full fan automation, as well as data transfer tra nsfer of drill plans and log files. If manual operation is preferred, the rig cabin offers a good working environment with vibration dampening and noise isolation. Compared to its predecessor, the Simba W469, W469, mobility has ha s been improved thanks to reduced rig length and a more powerful engine . This further reduces the drilling cycle. An important feature is the t he new water pump system, which increases the efficiency, reduces water spillage and lowers the overall cost. A new air venting system ensures longer pump life, and the pump pressure control has been modified to optimize ham mer efficiency. efficiency. Some special features of the Simba W6 C are: a reser ve hammer rack for four hammers; a place for reserve drill bits; a crane for heavy lifting; WLAN communication capacity; fan automation; tube magazine for 35 x 1.8 m long drill tubes for 63 m long holes; drill cuttings catcher; short rig length; robust construction; six cylinder motor; higher drilling capacity; accurate and easy set-up accuracy and ease of set-up; and automatic redesign of
Atlas Copco Simba W6 C at work.
the fan to planned hole ends, known as autospreading.
Drilling Drilli ng accuracy To achieve the demands for dr illing accuracy, with a hole deviation of less than 1%, it is important to select the best possible poss ible tool toolss for the ta task. sk. ITH pro pro-duces very straight holes, with an even penetration penetr ation rate throughout. throug hout. To To further fur ther improvee drilling improv drill ing accuracy, hammer and guide tubes are used, both equipped with a guide skirt.
Rotation and feed pressures, feed speed, and impact pressure all are factors in achieving the necessary drilling accuracy. With the Rig Control System (RCS) on the Atlas Copco drill rig it is possible
to optimize the feed pressure by using Rotation Pressure Controlled Feed (RPCF). This function uses the rotation pressure to read the process within the hole and adapt the feed pressure acac cordingly. The RCS gives a constant rotation pressure that keeps the tube joints joints tight, and creates an optimized penetration rate. The feed pressure on the Simba W6 C is automatically controlled by the RPCF and kept at the correct level at all times. Without this function there is an increased risk of hole deviation. Due to the advanced control by using the rotation pressure as a master, the system has the capability of adapting the parameter for feed pressure according to the rock conditions.
Wassara W100 hammer used for ITH drilling at Kiruna.
PRODUCTION DRILLING IN UNDERGROUND MINING
63
AUTOMATED LONGHOLE DRILLING WITH SIMBA AT LKAB
application. It supplies two sizes of hammer to the Simba W6 C: the W100 for production drilling, and the W120 for slot drilling in Malmberget. The W100 has a required water flow of 200-350 l/min at 180 bar. For production drill ing, a bit size of 115 115 mm is used, together a 102 mm diameter, 1.8 m long specialized tube string. str ing. The W120 W120 is used for slot holes, which require a larger 165 mm diameter bit size. Water consumption of the W120 is 450-500 450-500 l/min l/mi n at 160 bar. bar. The drill string st ring for slot drilling is the same as for production drilling.
Slot hole drilling
Slot drilled and ready as a free face for blasting.
To keep a balance between high penetration rate and hole deviation, the feed speed is held back if it exceeds a preset l imit. The level is adjust adjustable able to different ground conditions, and the feed speed also alerts the operator to the need for drill bit change. The impact pressu re in the hammer must be adjusted regularly, so that it suits both local ground conditions and bit selection. With the RCS impact control there is a continuous adjustment of the impact pressure to match the ground conditions and the condition of the hammer, optimizing drilling performance.
Wassara hammers ITH drilling can be carried carr ied out with with water driven hammer or ai r driven hammer. The water hammer achieves a very clean working environment when compared to air driven hammers, which release dust and lubricated air into the drifts. Since all of the production drilling is upwards, the water hammer was the natural choice. Wassara is an LKAB-owned com pa ny sp ec ia li ze d in wa wate te r ha mm er
64
The production stopes at Malmberget are opened using the slot drilling technique, due to its eff iciency and flexibility. First a pilot hole is drilled with a specialized pilot hammer with guide tube and guide skirts to maintain straightness. The pilot hammer is then replaced with the slot hammer, using a lifting crane mounted on the drill rig. r ig. Attached to the slot hammer is a guide tube that will guide the hammer from the previously drilled pilot hole. A complete slot contains 10 holes, around which a num ber of of blast blast hol holes es are drilled and blasted. blasted. All drilling operations are controlled from the cabin, in case of spalling rock. All cabins are equipped with air conditioning, CD player, swingable seat, and large wi ndows for for maximum visibility.
Automatic drilling At LKAB the Simba W6 C machines are working with the highest level of automation, ABC Total, which provides a full fan automatic drilling system with only some initial steps needed from the operator. Within the ABC Total package there is also t he possibility to drill manually or with one-hole automatics, if preferred. All three levels have built in safety interlocks during the whole process, allowing the operator to leave the machine while drilling is underway. Motion sensors detect any body entering enteri ng the restricted restr icted area while the machine is working under full automatics. The machines carry on d rilling unmanned duri ng shift change, lunch
break and night shift, sh ift, adding valuable drill metres.
Rig Remote Access With increase of automation and decrease of manning, there is a growing need for remote surveillance. Atlas Copco has developed an interface with the rigs called R ig Remote Access, RRA. With RR A the user can connect the drill rig to an existing network system via LAN or WLAN. In LKAB the RRA is used to transfer drill plans, log files and to handle messages coming from the rig control system. This system is a 3-D program able to map the whole coordinate system of the mine. The drill plans are stored in an RRA server, which is connected to the t he whole network system both on surface and underground. From the access points underground, all data is received and uploaded to the rigs. The access points also work in the opposite direction, when the machine sends out messages on the network. The messages are picked up from specified IP addresses, and can be read from a laptop or PC located anywhere on the network system. Messages from the r igs could be log files such as quality logs, Measure While Drilling MWD files, or alarm messages. The RRA can also be used to overview the drilli ng process on the cabin display.. This display Thi s Remote Display function funct ion can be used for surveillance of the drilling process. By using specified IP addresses, it is possible to open the display menus from any PC or laptop. With RRA, all data handling in the mine has been simplified, resulting in increased productivity. The drill rigs can also work unmanned, whilst being monitored from a remote location.
Acknowledgements Atlas Copco is grateful to the managemanagements at LKAB Kiruna and Malmberget mines for their assistance with this report, and their kind permission to publish. The original paper by P. Ericsson of Atlas Copco and C. Griffiths of LKAB has been edited to style and space.
PRODUCTION DRILLING IN UNDERGROUND MINING
PRODUCTION DRILL RIG OVERVIEW
Modular program with maximum flexibility Type 4 Positioning: Rotation, 380° Tilt forwards, 30° Tilt backwards, 30° Side movement, ±1.5 m with sliding table Extra side movement, ±0.75 m with pendulum arm
Type 3 Positioning: Rotation, 380° Tilt forwards, 30° Tilt backwards, 30° Side movement, ±1.5 m with sliding table
Type M COP 34,44,54,64 COP 1838ME/MEX
Type L
Alternative pendulum arm with 90° turned feedholder
COP 1838HE/HEX COP 2550UX COP 4050MUX
Typ M3/L3 ypee M3 Type 6 Positioning: Rotation, 380° Tilt forwards, 45° Tilt backwards, 30° Sideways, ±1.5 m
Type M4
Canopy Telescopic and FOPSapproved
Extra: Turn table ±20° Cabin with panoramic view and FOPS-approved
Engine module
Type 7 Positioning: Reach, 3.5 - 5.1 m Rotation, 360° Boom up, 45° Boom down, 15° Sideways, Sidew ays, ±35° Forwards, 90° Backwards, 10°
Type M6/L6
Front module
Rear module
Type M7
7 0 0 2 G R E B M L O H A
Power pack
© Atlas Copco 2003
The Simba M- and L-series production drilling rigs represent a concept that makes the drilling unit easier to run and more mor e productive to use. “Drilling with precision” has been our motto and objective for both the mecha mechanical nical solutions and the electronic control system. Mechanical components and electronics represent the absolute best available, which is no small claim. And the Rig Control System (RCS) adds extendable intelligence. The endresults is a fleet of Simba rigs with the dynamic exibility to solve not just today’s needs but also tomorrow’s.
The M-series are tophammer production drilling rigs with RCS for high productivity and precision. Hole diameter range 51-102 51-102 mm and hole depth up to 51 m with Rod Handling System. Equipped with the well proven rock drill COP 1800-series (51-89) or COP 2550UX (89-102). Availabl Available e in four configurations M3 C, M4 C, M6 C and M7 C.
With four different drill units, three feed lengths, six tophammer rock drills, a number of ITH hammers and an extensive options program, we are able to offer the right Simba for every application. Each Simba rig is designed to be dismantled into its main components for ease of lowering into narrow shafts.
The L-series are tophammer production drilling rigs with RCS for high productivity and precision. Hole diameter range 89-127 mm and hole depth up to 51 m with Rod Handling System. Equipped with the well proven rock drill COP 4050MUX. Available Available in two configurations, L3 C and L6 C.
The M-series are also available with ITH hammers COP 34, 44, 54 and 64 for hole diameter range 92-178 mm. Available Available in three configurations, M3 C-ITH, M4 C-ITH and M6 C-ITH. Hole depth up to 66 m with Rod Handling System.
Visit www.atlascopco.com/cmt for more information PRODUCTION DRILLING IN UNDERGROUND MINING
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