The Mechanization of Haulage Drilling in the Gold Mines of Anglo American Corporation

The mechanization of haulage drilling in the gold mines of Anglo American Corporation

by J. w. WILSON*, Ph.D., C.Eng., M.AIME, F.!.Min.E., F.I.M.M. (Fellow), and J. G. TAYLOR*, A.C.S.M., C.Eng., M.!.M.M. (Visitor) SYNOPSIS Some one-thousand kilometres of tunnels are mined annually in the gold mines of South Africa. Until two years ago, mechanized drilling on South African gold mines was not an economic proposition because of the availability of inexpensive labour and the fact that mechanized equipment developed for other mining markets could not perform satisfactorily in the tough, abrasive quartzites of theWitwatersrand System. A project team from the Technical Development Services Organisation of the Anglo American Corporation, in t collaboration with various manufacturers of drill rigs and drill steel, has been concerned with the development of suitable equipment for mechanized main-haulage drilling. After two-and-a-half years of extensive testing and development of drifters, drill steels, and bits, many of the problems encountered have been sotved, and gradually jumbos mounting pneumatically and hydraulically powered drifters are being phased into production on various gold mines of the Group. A description of the development work is given, and actual operating results are recorded, together with details of the drilling and blasting techniques used. SAMEVATTING Tonnels met 'n gesamentlike lengte van ongeveer een duisend kilometers word jaarliks in die goudmyne van Suid-Afrika ontgin. Tot twee jaar gelede was gemeganiseerde boorwerk in Suid-Afrikaanse goudmyne nie 'n ekono- miese proposisie nie vanwee die beskikbaarheid van goedkoop arbeid en die feit dat gemeganiseerde uitrusting wat vir ander mynboumarkte ontwikkel is, nie in die harde, skurende kwartsiet van die Witwatersrandstelsel be- vredigende diens gelewer het nie. 'n Projekspan van die Anglo American Corporation se Organisasie vir Tegniese Ontwikkelingsdienste was, in samewerking met verskillende fabrikante van booruitrusting en boorstaal, gemoeid met die ontwikkeling van geskikte uitrusting vir gemeganiseerde boorwerk in die hoofvervoerwee. Na twee en 'n halfjaar se uitgebreide toetse en ontwikkeling van dryfklopbore, boorstaal en boorpunte is baie van die probleme wat teegekom is, opgelos en reusemasjiene waarop swaar pneumaties of hidroulies aangedrewe klopbore gemonteer is, word geleidelik by verskillende goudmyne van die Groep in gebruik geneem. Die ontsluitwerk word beskryf en werklike bedryfsresultate word verstrek tesame met besonderhede van die boor- en skiettegnieke wat gebruik is.

INTRODUCTION ated with the hand-held jack- conditions. This resulted in ex- hammer method with which cessive jumbo maintenance, The Anglo American Corporation ) jumbos had to compete. It was drill-steel damage, and poor Gold Division commenced trials with subsequently recognized that, penetration rates. mechanized haulage rigs or drilling in the context of the time value It must be appreciated that the jumbos in 1969, where the early of money, if a high-speed jumbo equipment was being used under types of machine tested were fitted could be perfected, the machine South African gold-mining condi- with pneumatic drifters and air- could still make a contribution tions, for which it had not been powered hydraulic systems. These to profits by permitting the developed originally, and the follow- early trials produced much valuable rapid opening up of an ore ing adverse factors weighed heavily information concerning the costs reserve, even though unit costs against the mechanized equipment. and practicability of jumbo drilling, would be higher. The time- but, like most experiments with (a) In the high-speed situation, the honoured South African shaft- prototype equipment, they failed jumbos were required to com- sinking practice with its very in the production situation, although pete with six highly flexible and high costs but high advance it became clear that the potential low-cost hand-held jack- rate serves as an example. did exist for jumbo drilling to hammers. become viable particularly for high- 2. The trials were conducted by (b) The jumbos were required to speed work. The main reasons for production personnel with drill in small tunnels of 3 m the failure of those early attempts prototype equipment under pro- by 3 m at great depth, which were as follows. duction conditions. Naturally detracted from the use of the 1. Unit costs were expected to enough, as soon as the inevitable well-known tunnelling tech- be lower in terms of metres of difficulties arose, resistance to niques of drilling a few large- haulage advance. This has change manifested itself be- diameter (50 mm) holes, rather subsequently proved to be very cause the people involved had than many more small-diameter difficult to achieve in view of production targets to achieve, (40 mm) holes, to break the the low costs of wages and the and had neither the time nor round effectively. In large tun- inexpensive equipment associ- the resources to develop and nels (5 m by 4 m), drillout improve the equipment. time can be substantially re- 3. The combination of jumbo car- duced by the utilization of *Gold Division Technical Development Services, Anglo American Corporation riage, booms, drifters, steels, large-diameter holes and large- of South Africa Limited. and bits was unsuitable for the hole burdens. In small tunnels

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY JANUARY 1975 151 this is not-the case, particularly earlier, unsuccessful attempts to chines. If extension rods have to be if cushion blasting of perimeter introduce jumbo rigs that there was used, 11 inch threads should be used holes is necessary. Furthermore, a need for a heavy jumbo that could on the drifter end of the steel. the blasting of large.diameter, replace the labour-intensive method With rifle bar rotation drifters, 61 heavily burdened holes under of high-speed development. The inch shank rods with forged collars stress at great depth causes advantages of such a machine would and It inch threads (double or excessive damage to the sides be that it could be made to exploit triple length) on the bit end are of the excavation. to the maximum the features in satisfactory. (c) In the case of a jumbo, two favour of mechanized drilling, and Drill Bits mechanized drilling units were that it would not be limited in its 40 to 43 mm heavy-duty, de- required to compete with six capacity by environmental factors tachable cruciform bits with large hand-held units. This meant such as heat and humidity. Accord- inserts (20 mm by 12 mm by 15 mm). that high penetration rates weer ingly, when the Anglo American The skirt must be 36 mm in dia- necessary. In an attempt to project team took over the jumbo meter and fitted with 1t inch reach this goal by the use of project, the objective was changed threads. Tungsten carbide inserts heavy striking drifters, failure of to that of developing a high-speed should be coarse-grained with a tungsten carbide inserts and drilling unit (even though it was relatively low cobalt content so that damage to drill rods became recognized that unit costs would they can withstand the high-power excessive in the tough, abrasive increase) that would exploit the transmission necessary for high pene- quartzites. following features, which favoured tration rates. (d) The compressed-air supply on a mechanized equipment and with With the aforementioned combin- typical gold mine can fall to as which hand-drilling could not com- ation, drilling costs are only slightly low as 400 kPa during peak pete adequately: higher than if 11 inch hexagonal rods periods, and the supply is (a) the use of high-power, heavily and 45 to 48 mm bits are used, but frequently erratic. While it is thrusted drifters to achieve the improvement in penetration rate a simple matter to provide an high penetration rates, is substantial and, as previously extra jackhammer if it is neces- (b) the ability to drill up to 4 m mentioned, 48 mm holes are com- sary to make up any shortfall rounds, pletely unacceptable in the small resulting from lack of com- (c) a reduction in labour, and tunnels of mines situated at moderate pressed air, in the case of a (d) elimination of arduous manual to great depth, particularly if prilled two-boom jumbo with large work and enrichment of the ammonium nitrate explosives are pneumatic drifters, there is little job of the operators. usedl. that can be done other than to A major breakthrough was During the development trials on provide a booster compressor. achieved when the technique of drifters, drill steel, and bits, hy- drilling small-diameter (40 mm) holes draulic drifters were tested and THE DEVELOPMENT OF by the use of high-frequency drifters evaluated together with several HIGH-SPEED JUMBOS was perfected during a prolonged pneumatic machines. The hydraulic testing and development trial with On the gold mines of the Anglo drifters proved to be particularly American Group, there is at present a various combinations of drifter attractive for the drilling of small- types, drill-steel sizes, and bit de- need to develop about 10 000 m of diameter (40 to 43 mm) holes using sign. It has subsequently been 3 m-by-3 m tunnel every month at light blows delivered at high fre- high rates of advance. This is usually satisfactorily demonstrated at quency. Compared with pneumatic done by double and treble shift work several sites, even in very hard machines, the drifters have the quartzite, that the following type under multi blast conditions. In addit- following advantages. ion, very much more tunnelling is car- of equipment will permit high pene- 1. The machines are more suited to tration rates to be achieved. ried out on Group mines where the high-frequency operation than target is low and, typically, three Drifter pneumatic equipment, and pro- men with two jackhammers drill a A light-blow, high-frequency 10 duce a higher input-output effic- 1,5 m round every day. In this latter to 15 kW output machine. The blow Iency. situation, a jumbo will not compete energy must be controllable between 2. The blow energy of the piston economically unless it can gain 150 and 200 J. Blow frequency 60 can, to a certain extent, be con- access to four or five ends a day, to 65 Hz, 3600 to 4000 blows per trolled to prevent insert shatter and this is not always possible in a minute. The machine must be in hard rock without the need for gold mine. However, as labour for thrusted at between 6 and 7 kN. a reduction in blow frequency. the gold mines becomes less freely Drill Steel With one of the latest hydraulic available, it could well be that 4 to 5 m long, Il inch hexagonal drifters available on the market, jumbos (probably smaller and more- fully carburized rod. Shank adapt- the penetration rate in hard rock versatile machines than the high- ors and couplings should be avoided. can be maintained by a sub- speed units) will be justifiable-if However, this is not possible at stantial increase in the blow not essential-purely as a means of present with hydraulic drifters be- frequency, even though the blow saving labour. cause of the high torques exerted energy of the piston may have It was recognized soon after the by these independent rotation ma- to be reduced significantly to

152 JANUARY 1975 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY prevent shatter of the carbide many years, been made to suit the seas suppliers of mining machInery insert on the bit. requirements of jack-hammer drill- were contacted and, after lengthy 3. A jumbo mounting hydraulic ing. Had it not been for the avail- discussions tempered by previous drifters would consume roughly a ability of light-blow, high-frequency experiences with jumbos on the third of the power required by a drifters, there is no doubt that, with gold mines, the following specifi- jumbo mounting pneumatic drift- the quality of tungsten carbide cations were drawn up for a jumbo ers of equivalent output. currently available (both local and to suit gold-mining conditions. THE SCOPE OF THE imported), high penetration rates in hard quartzite would not have been Specifications for High-speed MECHANIZED DRILLING Jumbos PROJECT attainable at tolerable unit costs. At the present time, the costs of 1. Drill Bits These would be re- When the Technical Development bits and steels with jumbo drilling quired to drill holes of about 40 mm Services Organisation (T.D.S.) as- account for up to 20 per cent of the in diameter in hard quartzite. The sumed responsibility for the mechan- total cost of driving a tunnel; tungsten carbide inserts should be t ization of main haulage drilling, a however, with the light-blow, high- , shatter-resistant and permit at least complete re-appraisal of previous frequency drifters and specially made 16 m of drilling before resharpening failures was carried out. It was de- jumbos, this cost is offset by high is required. The bits would be re- cided that future production trials rates of advance. quired to withstand the power would not commence before ex- It was recognized at the start of output of large, high-frequency, ;~ haustive development of equipment the T.D.S. project that, if jumbo heavily thrusted drifters. and pilot production trials had taken drilling on the hard-rock gold mines ,.::" 2. Drill Steels These would be . place. was to succeed, the equipment required to drill 40 mm holes and ,,' ;.. These trials were conducted in would have to be tailor-made for permit the rapid flushing of chip- i hard quartzite at Western Holdings, conditions on these mines. It was pings. The steels would need to in the Orange Free State, and it clear that equipment developed for withstand thrusts of up to 8 kN became clear at an early stage that other markets would have limited without becoming damaged and the quality of local drill steel and or no application in the small tunnels without permitting hole deviation. bits was unsatisfactory for jumbo in hard, abrasive quartzite found in If possible, they should be shank drilling on the gold mines, probably the South African gold mines. Ac- rods to obviate the use of a combin- because the local products had, for cordingly, several local and over- ation of shank adaptor and coupling-

Plate I-Atlas Copco Promec TH 260 SA mounting Cop 1038hydraulic drifters

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY JANUARY 1975 153 and-extension rod, because these rod to be held firmly to prevent hole in an explosive atmdsphere, and to are liable to breakage and cause deviation. The intermediate guide maintain delicate electrical circuits blow loss, which results in heat should travel with the drifter so that free of water, dust, and water-oil generation at the coupling. Further- it is at all times mid-way between mist. more, the combination is very ex- the drifter and the front guide. 9. Carriage This should be sturdy pensive compared with a shank rod, 6. Booms These should be simple and articulated to permit travel on and drills a shorter-length hole for a (preferably of the rotaboom type) 20 m-radius curves and to permit the given length of feed beam. and should permit the automatic mining of 40 m-radius curves. The 3. Drifters These should be high- drilling of holes parallel to one slewing device should be hydraulic- power output machines that permit another. An hydraulic hoses should ally operated by a hand pump. The maximum penetration rate to be be neatly disposed to avoid damage whole carriage should be capable of achieved. The only machine capable caused by fouling on boom append- being lifted off the tracks in the i:" of high-power output that does not ages during operation. drilling mode by hydraulic jacks. cause excessive damage to the drill 7. Hydraulic and Pneumatic Con- The unit will operate in a 3 m-by- bit and drill steel is the light- blow, trols and Gauges These should be 3 m tunnel with at least one 550 mm I! ii high-frequency drifter described arranged so that the operator has an ventilation column equipped to with- i' earlier. unrestricted view of the tunnel face in 3 to 12 m from the tunnel face. !1 ,j 4. Feed Beams These should permit and the various pressure gauges that Plates I to III show the type of drifter travel of at least 4 m, and are important for control. These jumbo that has been evolved as a I: they should be fitted with hose reels should include gauges for water result of collaboration between the to prevent all travelling hoses to pressure, air pressure (for pneumatic T.D.S. project team and two large the drifters from fouling various rigs), and drifter thrust and piston manufacturers of equipment. The boom and other appendages (e.g., blow energy (for hydraulic drifters). three jumbos conform, for the most slide rails on the tunnel floor). 8. Electrical Systems All lighting, part, to the specifications mentioned 5. Front and Intermediate Drill- electrical power, and control systems previously. steel Guides These should be wear- should be placed in approved flame- The mines in the Gold Division of resistant and should permit the drill proof containers to prevent ignition Anglo American Corporation will, in

Plate II-Atlas Copco Promec T 260 SA mounting Cop 125 pneumatic drifters

154 JANUARY 1975 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY Plate III-Montabert ACH. 5 Pantofore mounting H45P hydraulic drifters

the next few years, purchase several Promec TH 260 SA jumbo and a ditions, and, in order to balance the of the types of jumbo specified above. second ACH.5 Pantofore will be cleaning cycle with the drilling and The machines will be used for high- delivered to gold mines of the charging cycle, a 4 m round requires speed development work, which has Anglo American Group. to be cleaned in 2 to 3 hours. become necessary because of the To achieve this with rockershovel opening up of new shaft systems at Future Jumbos loaders and railbound hoppers, the several mines, and also because The ncxt stage of development in tunnel layout must provide for large ore reserves, which were pre- this project is the perfection of shunting bays for a single hopper viously unpayable at lower gold smaller, more-versatile jumbos that every 50 m along the tunnel, and prices, now require to be developed can be used on mines for the sliping the main access crosscuts between and exploited. The following jumbos of boxhole excavations and the the tunnels should be positioned have recently commenced production drilling of roofbolt holes. In add- 180 to 200 m apart. The trials on Group gold mines: ition, negotiations are currently rockershovel loaders should have a 1. ACH.5 Pantofore (Vaal Reefs being conducted with various manu- bucket capacity of 0,4 m3, with a South, operating for 2 months), facturers for the supply of a boom maximum theoretical loading rate 2. Promec TH 260 SA (Welkom and feed that can be used to drill of 150 tjh. At least twenty 6 t No. 3 Shaft, operating for 3 roofbolt holes, as well as to install hoppers are required to clean a 4 m months), and and tension roofbolts. round. Two locomotives are 3. Promec T 260 SA (Welkom CLEANING OF LONG ROUNDS necessary, one being a 5 t unit for No. 2 Shaft, operating for 8 shunting hoppers from the face to months). The high-speed jumbos were de- the shuttle point, and the other an In the next few months, a second veloped for twin-end multiblast con- 8 t unit for tramming full hoppers

JOURNAL OFTHE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY JANUARY 1975 155 from the shuttle poInt to the maIn plosives because of the brittleness of omega cUps. rockpass tip point. the quartzite. Igniter cord and 2,1 m long fuses If extensive roofbolting is neces- Figs. 1 and 2 illustrate typical are used for the timing and initiat- sary for temporary support follow- rounds drilled in soft and hard ion of holes; however, results have ing a blast, then the round may well quartzite respectively. The terms not been satisfactory to date, and have to be cleaned in an hour in 80ft and hard relate to the drill- on many occasions the outer holes order to balance the drilling and ability (and to a certain extent the have misfired. Accordingly, steps charging cycle with the cleaning compressive strength) of the rock, have now been taken to introduce and roofbolting cycle. In this situa- and, as a rule, the easier it is to electric detonators for the blasting tion, expensive and sophisticated drill a particular type of rock, the of development headings in Group cleaning equipment will have an easier it is to break with explosives. gold mines where long rounds are application. The T.D.S. project team Either prilled ammonium nitrate being drilled. is currently investigating the acquis- (Anfex) or 38 mm-by-560 mm 60 per Various types of 'cut' have been ition of a shuttle train of HO t cent Dynagel cartridges are used for employed successfully, and these capacity for use where 4 m rounds in the charging of all holes except the can be roughly classified as 'burn 3 m-by-3 m tunnels are required to be perimeter holes. Cushion blasting cuts' and 'shatter cuts'. cleaned within an hour. of the 40 to 43 mm perimeter holes is For the purpose of this paper, a achieved by charging the holes with burn cut is defined as a cut in which OPERATING RESULTS WITH 22mm-by-200mm 40 per cent each hole breaks either into the void PROMEC T 260 SA JUMBO AT dynamite, and the cartridges are of the stab hole or else into the void WELKOM GOLD MINE NO. 2 spaced at 200 mm intervals in created by the detonation of previous SHAFT The jumbo has been operating for a period of about eight months, and it is felt that the results obtained so . . . . far are reasonably representative of what to expect from this type of equipment. The machine is operating in a single end that is blasted once in 24 hours. A long round is . . essential, and the cleaning is being carried out on night-shift using small conventional 0,26 m3 rockershovel loaders and 4 t hoppers. As mentioned previously, production . . . . trials with a Promec TH 260 SA . jumbo at Welkom Mine No. 3 Shaft and with an ACH.5 Pantofore at . Vaal Reefs (South Division) also . 0 . . commenced recently, but it is still . too early to report on operating . results. The Promec T 260 SA jumbo at . Welkom No. 2 Shaft was the first . . . . of its type to be built, and resulted from collaboration between T.D.S., Delfos, and Atlas Copco. Prior to this, the unit was used for eighteen months at Western Holdings for . . . development tests on bits, steels, and drifters. The booms on the rig were originally purchased in 1969 and were used on an earlier jumbo . . . . built at Western Holdings. Type of Round Drilled The number of holes drilled de- pends entirely on the characteristics 0 U"'[I-HH~G[D of the rock. It is well known that tough, abrasive quartzite, although . [1-I~Rb[D very difficult to drill, is usually relatively easy to break with ex- Fig. 1-30-hole round for soft rock (tunnel 3m by 3m. hole diameter 40 to 43mm)

156 JANUARY 1975 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY . I

successfully, and Figs. 5 and 6 . . . . . illustrate equally successful shatter ... cuts. Both prilled ammonium nitrate (Anfex) and 38 mm-diameter 60 per . . . cent Dynagel cartridges are used in . . all four types of cut with equally . . satisfactory results. DATA ON THE PERFORM- . ANCE OF THE T 260 SA JUMBO . . . . The Promec T 260 jumbo at 0 0 Welkom No. 2 Shaft is being used to . drill in an intershaft transfer haulage . . o . . being mined at t per cent down- grade to No. 3 Shaft. The best 0 . 0 advance achieved to date in a single . . month has been 100,2 m in 25 blasts. . . Special 4,95 m-by-l! inch hexagonal . imported carburized drill steels were used to enable 4,0 m long holes to be . . drilled. The haulage is cross-cutting the . . strata, and the bedding planes dip towards the face at about 30°. The . . . formations vary considerably in strength and drillability, and have yielded valuable data on the life of . . . . . tungsten carbide, the life of drill steel and thread, penetration rates, and optimum drifter characteristics. The rocks form part of the deep foot wall formations of the lower 0 Uhl[I-I~QG~D Witwatersrand System, and vary from soft, coarse-grained, yellow ~ [1-I~Q6b:D quartzites to hard, laminated, fine- grained, glassy quartzites. Fig. 2-4S-hole round for hard rock (tunnel 3 m by 3 m, cushion blasting of Prior to the arrival of the jumbo perimeter holes, hole diameter 40 to 43 mm) at Welkom Mine, the haulage was drilled with four, and sometimes holes. Each hole breaks out over its Drilling accuracy in the case of five, hand-held jackhammers drilling entire length and flushes most of shatter cuts is not quite as import- 3 m rounds. Because of ventilation the broken rock out of the cut. For ant as for a burn cut. restrictions, the tunnel could be this type of cut to break out cleanly, Both burn and shatter cuts have blasted only once in 24 hours. accurate drilling with all holes been used to pull 4 m rounds in 3 m- Table I shows an interesting com- parallel is essential. by-3 m tunnels. However, it should parison between conventional and A shatter cut, on the other hand, is be mentioned that the detonation mechanized drilling in the inter- one in which only the first one or of blast holes in shatter cuts is shaft haulage on 37 level at Welkom two holes break into the stab-hole likely to cause extensive fracturing Mine No. 2 Shaft. void, and even then not over the in the vertical plane when the holes It has been recognized at Welkom entire length of the cut. The holes are highly stressed (for example in a Mine that, unless effective preventive break out mainly by a process of deep-level mine)2. This occurs when maintenance is carried out and 'cratering' to the free face at the the holes have no parallel free face planned maintenance schedules open end of the cut. The detonation into which they can break, and drawn up and adhered to, the of each successive hole pulverizes consequently much of the explosive jumbo will not operate effectively and reworks the shattered rock in effort is expended in creating a and will break down during pro- the back of the cut and progressively crushed zone round the hole and in duction drilling. The satisfactory flushes out the broken rock. After extending tension cracks created performance of the jumbo has en- the last hole has detonated, the initially by the shock wave on the couraged full participation of the shattering and cratering of each instant of detonation. miner, fitter, and operators. Timeous hole causes the cut to break and Figs. 3 and 4 illustrate typical routine attention to minor items, flush out over its complete length. burn cuts that have been employed such as oil levels, leaking hydraulic

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JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY JANUARY 1975 159 TABLE I will permit the advance of the science A COMPARISON BETWEEN JACKHAMMER DRILLING AND JUMBO DRILLING AT 37 LEVEL of tunnelling. INTERSHAFT HAULAGE, NO. 2 SHAFT, WELKOM GOLD MINE P romec T 260 4 Hand-held jackhammers REFERENCES (drilling 4 m rounds) drilling 3 m rounds 1. WILSON, J. W., and TAYLOR, J. G. Labour required 2 Operators 4 Drillers Introducing mechanized haulage drill- 1 Bit changer 2 Assistants ing equipment into the Anglo American Corporation gold mines in South Productivity 1 to 1,5 man hours per 6 to 8 man hours per metre Africa. Paper to be published in Trans. metre of advance of advance Instn Min. Metall. 2. WILSON, J. W., and MILLER, H. D. S. Rates of bit Cop 125 drifter - 100 to 180 I Airleg mounted jackhammer Drilling and blasting in thin tabular penetration cm/min - 20 to 38 cm/min stopes at depth in hard-rock mines. Trans. Instn Min. Metall., Sect. A, Costs of bits and Hard rock R27 per metre of Hard rock R9 per metre of vol. 82. 1973. steels advance advance 3. Research review, 1971. Chamber of Soft rock RIO per metre of Soft rock R5 per metre of Mines of South Africa. advance advance 4. SINGH, D. P. The drillability of rocks. M-iner. Sci. Engng, vol. 5, no. 3. Consumption of 26 to 38 kg per metre of 30 to 38 kg per metre of July 1973. explosives advance advance

Holes per round 30 to 45 35 to 45 Contribution to the above paper by I. H. MacConachie* Drilling time per Hard rock 2h 10 min Hard rock 4h round Soft rock Ih 20 min Soft rock 2th Dr Wilson and Mr Taylor are to be No accurate figures for the costs of spares and maintenance for the jumbo are congratulated on their excellent available at this stage. paper, and also on the manner in which the paper was presented. It was very interesting to note that hoses and connections, faulty pneu- tunnelling engineers is that they they stressed the importance of matic and water hoses, tensioning of have no universally acceptable, ac- maintenance, and that Welkom Mine the feed chain, bolt and nut tighten- curate method of comparing the recognize that planned preventive ing, rebuilding of worn front and drillability characteristics of the maintenance schedules must be ad- intermediate guides, and inspection rock in which they are mining. hered to if their jumbos are to of water tubes and lip seals, has Comparisons of compressive strength operate effectively. obviated many a production break- do not necessarily reflect accurate From a manufacturer's point of down. comparisons of drillability3, and it view, one of the most important has been shown on this project that CONCLUDING REMARKS specimens of the same rock type aspects in the commissioning of a jumbo rig is training in maintenance. (glassy Witwatersrand quartzite) The development and operation We appreciate that the introduction that have the same compressive of the Promec T 260 SA jumbo of hydraulic equipment creates an strength can have very different bears testimony to the devoted abnormality compared with the well- drillability characteristics. This effort of many pcople both inside accustomed maintenance of units phenomenon has led one author4 to and outside the Anglo American such as locos, loaders, winches, and conclude 'that the best method of Corporation. The machine was pumps. Here, we cannot overstress specially designed as a result of determining the drillability of a the inevitable need for cleanliness given rock is to drill that rock'. previous failures, and the drifters, during any form of repair to hy. steels, and bits used on the Promec However, when a choice of cquip- draulic equipment. To cater for this ment has to be made for a tunnclling T 260 SA today are very different new concept of hydraulics, it has project, it is rarely practicable to from the equipment used in South been necessary to introduce a com- conduct drillability tests with several Africa and elsewhere even up to two prehensive training course for en- different types of drifter and with years ago. The light-blow, high- gineering personnel so that they will frequency drifter has firmly estab- various combinations of drill steel have a far better understandinO' of and bit. The problem would be lished itself as the only machine the equipment that they are'"' ex- slightly simplified if the tunnelling capable of drilling holes in tough, pected to maintain. The course, engineer knew at least the output abrasive quartzite at rates of up to which is normally run a few weeks characteristics of the various drifters 2 m per minute. As a result, it can prior to delivery of a jumbo and safely be said that the concept of he was considering. Regrettably, lasts for three days, comprises the high-frequency drifters drilling small only one or two manufacturers of following. drifters publish figures on the blow- holes will gain in popularity for other 1. Basic Hydraulics energy of their equipment, and it is tunnelling applications, and this will This covers hydraulic circuit dia- felt that tl:e time has come when automatically herald the intro- grams, symbols, and components. A manufacturers of percussion equip- duction of hydraulically powered programmed instruction method is ment should be required to publish, drifters with all their attendant employed, which is a form of self. advantages. among other things, figures for blow Finally, it must be mentioned that frequency and energy per blow that one of the great difficulties facing are universally acceptable and that *Delfos and Atlas Copco (Pty) Ltd.

160 JANUARY 1975 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY instruction, and one of the main Hgh-d:v;dend rewarder ofprcduction. Lost blasts represent 30 per cent, advantages is that trainees work at which is high. their own pace and learn in the Contribution to the above paper by R. A. R. Kebble* 4. Total blasts taken were 102, shortest possible time. of which 25 were 2 m rounds while 2. Practical Application of Hydraulic Towards the end of July this year, negotiating poor ground. These 25 Components the Promec T.H. 260 SA, which is a short rounds gave an advance of The trainees are given various hydraulically operated jumbo rig, 58,3 m. The remaining 77 blasts components that are used on jumbos, was introduced in Welkom Gold gave an advance of 267,7 m, which and they strip and re-assemble them Mining Company No. 3 Shaft. This is 3,48 m per blast. This figure is under the supervision of specialists. drilling rig is a prototype, and adversely affected by the fact that Here, experienced technicians pass nothing of this description had ever an extremely hard dyke was on their knowledge about the correct been used in the South African traversed for some 70 m. The best procedures in maintaining and over- gold-mining industry before. achievement to date for 26 shifts hauling these components to achieve The rig was to be used on an has been an advance of 140,8 m. maximum life with minimum break- experimental basis and was put into 5. The total advance done to date, down. operation in a single end with including that done by jackhammers, 3. Preventive Maintenance multi blast conditions on double shift. is 826 m; 580 m remain to be done The short-term and long-term This end had about 1150 m to go to holing. maintenance schedules are covered from No. 3 Shaft to hole with a 6. The amount broken per metre in lectures and demonstrations, the similar end from No. 2 Shaft. of advance is 30,25 t. importance of these schedules being Prior to actually being put on 7. Type of Round: stressed and examples of neglected production, the rig was tested on a 7 hole slit burn components being on view during test site underground for two weeks, 43 holes 1 round the course. mainly for the purpose of training 43 mm drain holes 4. Trouble Shooting the Black operators and setting the 3,7 m deep. This is a most important function hydraulic pressures. On the 8th of The best drill-out time for a 38-hole in maintaining the high utilization August, the machine was put onto 3,7 m long round has been 1 hour of mechanized machinery. The train- production on the working face, 5 minutes. The average advance of ees are instructed in pin-pointing and the hand-held jackhammers drill steel was 2 m/min. faults by the use of simple tests that were withdrawn, being used only 8. Explosives Used: give accurate information, so allow- for the drilling of roofbolt holes. 38 mm-by-560 mm Ammon gelig- ing faults to be rectified in the Statistics nite 60 per cent for cut and easers. minimum of time. Any faults should Periphery holes are charged with be systematically traced by adoption 1. The development end is situa- 25mm-by-200mm 60 per cent of the prescribed method of the ted some 1139 m below the collar of Ammon gelignite using Omega clips step-by-step elimination of faults. the shaft and initially had to traverse with a 200 mm air space. In this way, down-time is kept to a the Gold Estates conglomerate until 3,6 m fuses with 6D detonators and minimum. the intersection of the Arrarat slow igniter cord are used. On-the-J ob Training Fault, at which stage the end went Because of some cut-off problems Apart from this three-day course, into deep footwall quartzites of the with the lifter holes, electric deton- on-the-job training is given to the Witwatersrand System. This portion ators are being considered. engineering personnel for the first of development was done by hand- 9. Costs: Steel-and-bit costs have week. Maintenance schedules and held jackhammers. been very good, and are running at lists of spare parts are handed over 2. The end is upgraded at 1 :200. about R7 per metre advanced, and are explained in detail. Size: 3,2 m wide X 3,4 m high which is only slightly higher than The operators are fully trained for Equipment: 760 mm exhaust column jackhammer costs. The pneumatic a period of two to three weeks, and 570 mm force column drifter has a steel-and-bit cost of during this training period they are Using exhaust overlap R26 per metre advanced. instructed in daily routine mainten- system ance, which can be classified as the 60 lb rails 10 inch air Some Problems with the Use of most essential maintenance done on column 6 inch water. the Ri~ 3. Up to 2nd November, 1974, any drill rig. It is carried out by the 1. Preplanning from its inception, there have been operators at the end, or before the The foreseeable problems were 147 potential blasts of which 45 start, of the drilling shift. The ironed out before the rig arrived by have been lost owing to: production officials can assist greatly having meetings with the research by motivating the operators to be Cleaning...... 14 Machinefaults...... organization and the manufacturers. conscientious in this maintenance. 8 This was invaluable in preparing the In conclusion, it should be recog- Electric trailing cable 8 Support of bad ground. . . road for the advent of the machine. nized that a rig is an expensive and 8 2. Ground Conditions sophisticated item of equipment, Others 7 """'" The condition of the quartzites which, when given the care and being traversed leaves much to be maintenance it demands, will be a *Welkom Gold Mining Company Limited. desired, being rather soft and being

JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY JANUARY 1975 161 'very close to A, dyke that tunS and less enthusiastic person. the cable. parallel to the haulage. Some bad younger developer has proved more The O-rings in the collectors give falls of ground have caused delays, adaptable, and has accepted the rig trouble when steel sticks in the face. and roofbolt support on a very with far more alacrity than the latter, The electric panel on the drifter close pattern has to be kept right up and has been a greater success. originally gave trouble, but these to the face. It is necessary to appoint an problems have been overcome. 3. Cleaning Equipment adaptable and progressive-thinking Because of its technical sophistic- The cleaning equipment available person to this job. ation, the machine has proved for this development consists of an 5. Water Pressures difficult to maintain. Atlas Copco L.M. 56 loader and The water pressure on this level Conclusion 4 ton Fragran Hoppers. Two Diesel is high, and, as a result of the static I feel that the pneumatic rig is a locos of 3t ton capacity are used for pressure, many water-feed hoses less difficult rig to introduce into the moving the rolling stock. The average burst. A pressure regulator was in- gold-mining industry at present. cleaning time at present is about stalled to overcome the problem. When the difficulties have been 5 hours, which is unsuitable. Larger 6. Machine Faults ironed out of the hydraulic rig, it cleaning equipment is essential. The hydraulic hoses initially in- will be a superb machine. The 4. Selection of Personnel stalled were inadequate, and as a Cop 1038 Drifter has given out. Black operators were chosen from result tended to burst. standing performance, and this the mechanically-minded category. The electric trailing cable should drifter, in conjunction with a well- They seem to have no difficulty in be accommodated on the rig itself. tried and proven hydraulic operating the machine. After experiencing much damage to jumbo, would be of great value to a The two developers selected for the the cable as a result of rough high-speed development project. It job were of above-average calibre, handling, we put a cable car in would be encouraging to see a roof. one being a young enthusiastic man tandem with the rig, which has bolt drilling boom incorporated in and the other a more experienced afforded better protection to the this drill rig.

Drilling, Blasting, and Ore winning

A General Meeting and Colloquium E. J. Fox, N. T. Halgreen, L. A. by A. J. A. White, Dr N. C. Joughin, on the above subject was held on Jagger, J. Nortjie, B. W. Pitch- and Dr N. G. W. Cook, Chamber of November 13th, 1974, at Kelvin ford, A. Schmidt, B. M. L. Smith, Mines Research Laboratories. House, Johannesburg. M. Sturgeon. A comparison between hydraulic Professor R. P. Plewman (Presi- Transfer to Fellow R. C. Bertram. and pneumatic rockdrills, by T. C. dent) was in the Chair. Transfers to Graduate G. A. Fourie, Marshall, Delfos and Atlas Copco The Colloquium was attended by A. P. S. Howard, K. B. Perel. (pty) Ltd. 235 delegates and was opened by I welcome the newly elected The mechanization of haulage the President at 09h30. members of the Institute, and con- drilling in the gold mines of Anglo Obituary gratulate those who have been American Corporation*, by Dr J. W. 1. D. B. Corner, Fellow. transferred to a higher grade. Wilson and J. G. Taylor, Anglo In memory of the deceased and in Co-optation to Council American Corporation of S.A. Ltd. sympathy with the bereaved, the The President: I have pleasure in Session Chairman: Mr D. M. delegates rose and observed a few announcing that Mr H. M. Wells has McIver. been co-opted to fill the vacancy moments' silence. Second Session created on Council by the resignation Membership Prediction of the performance of of one member, while Mr E. Collier The President: I have much explosives in bench firing, by C. M. has been co-opted to represent the pleasure in announcing that the Lownds, AE & Cl. interests of the non-corporate mem- undermentioned candidates, whose The organization and manage- bers of the Institute. names have been published in ac- ment of a large mechanized colliery, cordance with By-Law 5.2.2., have The meeting ended at 09h45. by G. C. Thompson and P. G. The Colloquium Chairman was been elected to membership of the Henderson, General Mining and Fin- Dr M. D. G. Salamon, ofthe Chamber Institute in the following grades: ance Corp. Ltd. of Mines of South Africa. Fellows P. P. Coetzer, B. K. Love- Session Chairman: Mr R. B. The following papers were pre- day, J. L. M. McGibbon. MacGillivray. Member J. J. Marais. sented. Graduate R. Winby. First Session Associate P. L. Rossouw. Improvements in stope drilling Students R. A. L. Atkinson, G. Bull, and blasting for deep gold mines*, *Included in this issue of the Journal.

162 JANUARY 1975 JOURNAL OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY