NOTES FROM UNDERGROUND

On average, crews spent 0.9 manhours scaling when POWERTRIM was used compared with two manhours using AMEX. The perimeter holes were fired last in the round, so the method is not a pre-shear.

“Our operating costs were somewhat higher using POWERTRIM,” Division Supervisor Martin Sutherland says, “but we’ve seen a dramatic change in safety due to the lower overbreak.” Two extra holes had to be drilled and loaded using POWERTRIM.

Another innovation devised by the study group which conducted the trials was to use a plastic “birdie” (much like a badminton birdie) in the open end of the hole to hold the explosive in the hole during the blast. “There was not a lot of science involved in this program, but the idea works fine,” Sutherland says. For more information on POWERTRIM, Circle Reply Card No. b020 Shedding Light on Blasting Safety Longhole drilling and blasting are considerably safer and more efficient at Noranda Inc.’s Geco mine, in Manitouwadge, Ont. There are two reasons, according to Mine Captain Gord Marjerrison. The first is the introduction of the latest in blast detonators — a product called Photodet, manufactur ed by C-I-L. The second is the introduction of a computer-aided- design and surveying program into the mine-planning office. Those programs were written (in AutoCAD LISP) by Glen Wilson of Noranda Information Services in Toronto.

The Photodet system uses light of a particular frequency to initiate blasts. A specially coded electrical signal is needed to light a bulb in the Photodet coupler. This light activates the detonator by charging a capacitor, which, when fully loaded, then initiates the blast through the blasting line.

What makes this system much safer than conventional electrically initiated blasting systems, according to W. Webster and D. A. Doucette of C-I-L, is the air gap between the light bulb and the capacitor. The presence of that gap means all extraneous electric current in the mine can not possibly initiate the blast. Any extraneous current will light the bulb, but only the coded electrical signal will cause the bulb to produce the frequency of light necessary to charge the capacitor.

Blasters at the Geco mine have been testing the Photodet system since November, 1988. “We have found that we cannot proceed with using the system until some changes are made,” says Lester Kneen, technical engineering supervisor at Geco. “We have told the manufacturer that we have to turn the exploder key on to check the system and this could set off a blast if a key is inadvertently inserted in the wrong exploder. We should have a separate checking unit shortly.”

To help speed up the blasthole design and layout process, Geco has introduced the use of a powerful blasthole layout program developed by Noranda’s independent business centre known as Noranda Information Services. Since its introduction into the mine in December, 1987, the system has been used to design 200,000 ft of longhole blasting at Geco. “It’s not necessarily better than doing layouts manually,” Kneen says, “but it gives you more time (about 20%-30% more) to design the layout.”

It takes about two weeks for a technician to learn Autocad and an additional week of training to learn the blasthole layout program. For more information on Noranda Information Services, Circle Reply Card No. 22 For more information on Photodet, Circle Reply Card No. 23 Tube Rods and Computerized Drills It’s not often that a drill rod manufacturer introduces something new. So it was with noticeable excitement that Lennart Ermebrant, plant manager for Secoroc AB of Osteraund, Sweden, presented the operating results on the company’s new tube rod drilling system to the Sudbury gathering. (Atlas Copco recently acquired Secoroc.)

The concept is elegantly simple. By using large-diameter drill rods, both the speed and accuracy of rotary/percussion drilling can be increased. The large-diameter, thin- walled, blasthole tube rods, for example, have doubled penetration rates in some tests compared with smaller- diameter rods. One reason is the higher flushing pressure achieved in the hole because the larger diameter of the tube rods decreases the area through which the cuttings are flushed to the top of the hole. This factor becomes important in long holes and in ores which have a high specific gravity and therefore need higher pressures to get the cuttings to the top of the hole.

Accuracy of drill holes, too, has been improved through the use of tube rods because of the increased stiffness of the rods over conventional rods. Testing so far has also answered concerns about the life (and therefore the costs) of the rods. Tube rods are being tested in at least two Canadian mines — Brunswick Mining & Smelting’s No. 12 mine in Bathurst, N.B., and Hemlo Gold’s Golden Giant mine in Hemlo, Ont.

Rods used at the Golden Giant mine are three inches in diameter and are being used to drill 3 1/2-inch diameter holes with a Tamrock Data Solo 1008 computerized drill rig. That test started in May, 1988 and some 70,000 ft have been drilled in the mine’s large blasthole stopes so far. Hole deviation of only 1.5% over a length of 35m has prompted Hemlo Gold to order a second machine. One hole, using the Data Solo, took just one hour and 40 minutes to drill, compared with double that time using other machines and rods. Rod life is about 750 ft per tube.

Tube rods at the No. 12 mine are 3 inches in diameter and are being used on an Atlas Copco simba top hammer drill to drill holes 3 1/2 inches in diameter.

The smallest bit size which can be used with tube rods currently available is 89 mm. Maximum bit size is six inches. For more information on the Data Solo 1008, Circle Reply Card No. 24 For more information on the SIMBA drill, Circle Reply Card No. 25 For more information on Secoroc tube drills, Circle Reply Card No. 26 Drifter Advance Hydraulic drifters have come a Hlong way since they were introduced into Canada in the early 1970s. Montabert sa of France, one of several manufacturers competing in the Canadian market, has introduced a third-generation drifter.

The advantage of the new drifter, the HC-40, according to Tanguy De Brosses of Montabert, is its energy efficiency. The new drifter transmits energy from the piston to
the bit more efficiently and some of the energy that rebounds from the bit is recovered in hardrock drilling.

Tests at Montabert’s lab in France have shown that the efficiency of energy transmission through drill rods depends on the form of the shock wave, De Brosses says. A trapezoidal wave form is more efficient than a rectangular wave form, the company concluded. So Montabert has designed a third-generation drifter with a piston that can deliver a shock wave with a trapezoidal form.

Another design change, which adds to the efficiency of the company’s new HC-40 drifters, deals with the way hydraulic oil is regulated in the machine. The new drifter can store the energy from the return shock wave via an energy recuperation system. This system offers a progressive reaction to ground conditions, allowing an even reaction to changes in the torque opposing bit rotation.

The new drifters have been tested extensively by Denison Mines in Elliot Lake, Ont., by Cambior Inc. at its Yvan Vezina mine in Quebec and by Rio Algom at the Quirke mine in Elliot Lake. For more information on Montabert drifters, Circle Reply card No. b Raiseboring A new way of driving fill raises at LAC Mineral’s Macassa mine has helped this Kirkland Lake gold producer improve the safety of stope development while reducing the time required to bring a stope into production.

In the summer of 1987, a Redbore 40 raise bore machine, manufactured by J.S. Redpath, was introduced to the mine. Rockbursting is the main safety concern when driving raises conventionally at Macassa. Overhand cut-and-fill is the main mining method at the mine. The Redbore 40’s light-weight, m odular design is ideal for moving along the 6×7-ft track drifts, according to Ted Nelson, area chief engineer. The 125 KVA power requirement posed no difficulties either. The machine was controlled entirely from a remote console.

Nine-inch diameter pilot holes were driven and 4-ft and 5-ft-diameter reaming heads, dressed with tungsten carbide insert cutters, were used on five separate raises driven in ore.

From the test program, LAC found that the total cost of a linear foot of raise using the machine was competitive with conventional, manual methods. Costs were $368 per foot compared with $303, according to Nelson.

The time required to drive the raises, which are used for fill, ore and waste passes, has been significantly shortened to one week compared with two months driving the raises manually. That has made several stopes available for production earlier using the new mechanized method. For more information on the Redbore 40, Circle Reply Card No. b Canadian Jumbos go to Japan One multi-national hydraulic drill-manufacturer which has made a mark for itself in Canada recently is Boart Canada. In the past year, this company has built an impressive niche for itself within Boart’s worldwide organization. Today, it has earned a reputation as one of Boart’s centres of expertise in hydraulics. The other centre is the company’s plant in the U.K., where its hydraulic drifters are manufactured. The Sudbury plant is noted for its expertise in hydraulic booms.

In the past year, Boart has made two important breakthroughs in the international marketplace. One sale, of two 2-boom electric-hydraulic jumbos, will be shipped to Japan this spring. Equipped with Boart’s BDS 70-2000 booms and HD-150 drifters, they will be used by N & S Ltd. of Tokyo to drive two 2-km highway tunnels through the mountains of western Japan. The drills are mounted on a Komatsu WA250 carrier.

The tunnelling project, known as the Fukuyama project, involves driving the two tunnels through hard granite. “The reason we chose Boart was because of its simplicity of design and easy maintenance,” Nobumasa Shoji, president of N & S says.

Each rig can drill off a tunnel face measuring 11×8 m. Japan is one of the hottest civil tunnelling areas in the world with more than 200 tunnels under construction, Shoji says.

Boart Canada built the two rigs from scratch in three months but could probably build a third machine much more quickly. “It was a team effort from day one,” Mike Lahaie, a mechanic in the component area told The Northern Miner Magazine, “and it required a lot of planning and involvement of everyone from management right down to the mechanics.” Being situated in Sudbury was an advantage to Boart. “It’s amazing what materials and skills are available right here,” Lahaie says. “A lot of people bent over backwards to get the business. And we probably got it at one-tenth the cost of the same work done in southern Ontario.”

The other sale, one Stopemaster longhole machine, was made recently for a 12,000-ton-per-day underground copper mine in Zambia. For more information on Boart Canada, Circle Reply Card No. b Thick and Creamy At two of Inco Ltd.’s 10 nickel/copper mines in the Sudbury Basin, a white, cementitious foam, which resembles shaving cream, is being used successfully for a number of backfill projects. The material can support the weight of a miner shortly after it is poured. (The product has been used for severa l years in coal mines in the U.K. for filling cavities in underground mines and is marketed in Canada by Technik Mining.)

In August, 1988, crews at Inco’s Creighton No. 9 mine constructed a backfill barricade at the bottom of a vertical crater retreat stope on 5470 level of the No. 9 mine using the foam. The barricade was about 12 m wide by 7.5 m high by 21 m thick for a total volume of 1,890 cu m. One 25-kg bag of the material was mixed with 9 1/2 gallons of water every minute to pump one cubic metre of foam into the barricade every four minutes. It took about nine hours to fill the barricade, according to D. M. Clarke of Inco’s Industrial Engineering division. The result was a thick wall of the material with a compressive strength of roughly 35 lb per sq inch. The simple fence (constructed of timber, wire screen and fabrene) used to contain the foam was far less expensive and time-consuming than the elaborate barricades normally used by Inco to contain hydraulic backfill.

The success of this project has resulted in the construction of at least two other foam barricades in the Creighton mine.

The foam is also being used to fill cavities and control ground at Inco’s Levack mine. It has been used successfully there to contain uncemented backfill in some old boxholes on the 700 level so crews can mine high-grade ore left behind in the sill pillars. For more information on Technik Mining, Circle Reply Card No. b Continuous Loading There are several ways to reduce the risk of transferring new technology to a mine. One way, increasingly popular among machine-manufacturers, is to put a machine through its paces in an actual mining situation. Then, based on the machine’s performance, the potential buyer can decide whether to purchase the unit.

That method has been used at Brunswick Mining and Smelting’s No. 12 mine in Bathurst, N.B. In 1986, when the company decided to re- introduce blasthole open stoping, it shopped around for a better way to load muck into JDT426 haulage trucks. By 1990, the distance miners will have to haul muck to the ore pass on the 1000 level is expected to reach about 450 m, according to Jerome MacDonald, project technologist at Brunswick. So any machine which can speed up the mucking and loading part of the ore-handling cycle would lower the costs and increase the tonnes hauled per shift, the company reasoned.

An analysis of two competing continuous mucking machines was conducted in 1987. And from that work the Voest-Alpine AL60 loader, a crawler-mounted, fully hydraulic unit manufactured in Zeltweg, Austria, was considered more applicable at Brunswick than the competing loader, MacDonald says.

By January, 1988, the unit, which sits 3.5 m high, was assembled underground and went to work in a drawpoint measuring 4 m high and 5.5 m wide. Over the next 302 days, the loader mucked a total of about 97,000 tonnes of lead/zinc ore in 122 operating days. On average, 797 tonnes were mucked per working day.

Operator acceptance of the machine and the mechanical performance
were critically evaluated by Brunswick.

Overall, the test data showed that, compared with an 8-cu-yd scooptram loading JDT426 trucks, the AL60 is about two times more productive over haulage distances of up to 600 m. Other advantages include less operator fatigue, less noise, less heat and better visibility. Because the machine is powered electrically, ventilation requirements are also lower.

The biggest problem with the unit, MacDonald says, was its electrical design. Mechanically, the unit performed satisfactorily with little wear on the bucket.

Brunswick has submitted to the manufacturer a list of modifications it would like to see made to the machine, after which a decision on whether to purchase the unit will be made. “It’s still up in the air,” MacDonald says. One modification being considered is remote control operations. This would allow the unit to muck deeper into the open stope. The current configuration allows a miner to muck about 8 m in under the brow. Depending on the geometry of the stope, this can result in up to 35% of the muck in the stope requiring mucking by remote control load-haul- dump machine. For more information on Voest-Alpine, Circle Reply Card No. b Electric Haulage The proof of a good mucker is in Tthe mucking. The same holds true for hauling that muck. And the people who build Kiruna electric trucks now can lay claim to operating experience in two Canadian mines (after two years of giving presentations on hypothetical Canadian applications).

The two mines are Hope Brook in southwestern Newfoundland and Kidd Creek in Timmins, Ont. Each is using the new machine in quite different applications. Both systems were commissioned in late 1988.

Falconbridge Ltd. is using the 50-tonne-capacity truck to haul ore and waste from the 4600 level at the Kidd Creek mine to the 4400 level up a ramp driven at an inclination of –10%. The system is designed to transport 2,000 tonnes per day on a 2-shift basis using one truck.

A 1,000-V open bus system was approved for 4 m above the roadbed. The truck has attained speeds of 18 km per hour.

Initial results have shown that the on-board battery can be re-charged on each hauling cycle without negative drain on the nickel-cadmium battery pack, says Brock Morrison, product specialist for Atlas Copco Canada. The truck has to be disconnected from the overhead trolley line while loading and dumping.

At Hope Brook, two trucks are being used to supply 3,000 tonnes of gold ore to the mill. The initial application is to haul ore from chutes on the 4960 level up a 12% ramp to the crusher on surface. The haulage distance is 390 m. Later this year the trucks will be loaded by load-haul- dump machines and will haul ore over a distance of 1,500 m.

Speeds of 17 km per hr have been attained going up the ramp at Hope Brook and speeds going down have reached 22 km per hr, Morrison says.

Atlas Copco has also sold a truck to the Mount Isa mine in Australia. That truck should be operating in early 1990. For more information on Kiruna trucks, Circle Reply Card No. b

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