THE DRIVE TO SURVIVE

When Canada’s underground mine operators met in Elliot Lake, Ont., recently the talk was about how to achieve excellence when simple survival remains the first priority. By Patrick Whiteway Where are close to 300 mines operating in Canada and every one of them is run by people who are seeking ways to do their jobs more efficiently. Even the dozen new gold mines in the country are looking for newer, faster ways to bring their recently discovered deposits into production within the next year.

The reason is simple: metal prices. If operators of base metals mines don’t cut costs, the companies that employ them will shut down these mines and go where they can make a buck. That’s business. Often companies choose to leave this country entirely. Many head to Third World countries where government controls over the environment are far less stringent and where labor is cheap. The challenge facing today’s mine operators is ensuring that existing operations remain competitive.

For some mines, the solution comes in the form of cutting jobs and developing closer communications with all workers. For others, a solution lies in changing mining methods or using all-new equipment. Kiena Gold Mines, for example, took a bold new step in 1986 by using a full-face tunnel-boring machine (tbm) to drive two exploration drifts under Demontigny Lake, near Val d’Or, Que. (the machine is normally used for shallow, softrock civil engineering projects). While tbms have already been used in South African underground mines, this was the first such application in Canada. The operator was J. S. Redpath Ltd.

One of the 7.2-ft diameter drifts (1,685 ft long) was halted 3,000 ft short of its target because the machine performed poorly in harder-than- expected basalt. But the second exploration drift was driven 1,500 ft longer than planned, through a volcanic series consisting of komatiites, basalts and diorite. It was decided to go further on this drive because of the improved performance of the rebuilt machine. Average advance rates in this drift were 35.18 ft per day at a cost of $203.58 per ft, says Daniel Vanin, production superintendant at Kiena. “It is rare to see single-heading advance rates of more than 25 ft per day using conventional drill-and-blast techniques.”

One mine which hasn’t opted for new, high-technology equipment but which has stayed, instead, with the tried and true (pneumatic drilling in this case) is Brunswick Mining & Smelting in Bathurst, N.B. Robert Baker, supervisor of industrial engineering at Brunswick, says productivity gains in recent months have been achieved through close supervision and cost control. However, technical modifications have been made also. Changing to chain feeds from screw feeds on the company’s 15 pneumatic drill jumbos succeeded in cutting maintenance costs by more than 75%.

At the Ruttan mine, near Leaf Rapids in northern Manitoba, Sherritt Gordon Mines is using a new machine, which has made a significant change in the way it drills its upholes. From 1980 until just recently, the company used two types of drills in its blasthole open stopes. One drill was for 2-in holes drilled up from a drift to form a draw cone in the ore; another was for in-the-hole drilling of 6 1/2 -in holes, down to the cone from the drill drift above.

But now, by testing a new 4 1/2 -in in-the-hole machine, manufactured by Winnipeg-based Cubex Ltd., the company has made significant advances in mine productivity. The machine can drill upholes as well as downholes. “The new method is less messy and easier to schedule because we’re dealing with only one machine instead of two,” says John Stard, the mine’s general foreman. “It also requires only one man to do all the drilling.”

The cost of blasting using the new method is $1.20 per tonne compared to $1.37 for the 6-in holes and $1.29 for the 2-in holes. Stopes can now be designed 85 m high instead of the previous 75 m. Sherritt is also doing tests with Du Pont Canada to get a suitable blasting powder that will stay in the large-diameter upholes. “It looks like we’ve got the right product now,” Stard says. About 432,000 tons have been blasted using the new method.

The Ruttan mine has also introduced a new computerized mine maintenance control system for all its mobile and stationary equipment. Designed by Rushton International Maintenance Systems to extend the life of existing production and development equipment, the program is an on-line system that works on Sherritt’s mainframe computer.

“I think we have a good mechanical acceptance for the system,” says mine superintendent Jason McKenzie. Sherritt last purchased a major piece of equipment for the Ruttan mine in 1979. Although the company wrote off the $24.6-million carrying cost of the mine, published reserves are good for at least three more years and Sherritt plans to keep it in operation as long a it can produce a positive cash flow.

For other mines which have grown fat over the years, a solution to high production costs is being found in “labor rationalization.” But, as with technological change, the result is that some people lose their jobs.

Denison Mines’ uranium operations at Elliot Lake, Ont., are a good example of systematic manpower rationalization. A program was initiated in August, 1985, which reduced the number of people in three service- related job areas by 27% (down to 222 from 307). With 45% of the company’s operating expenses coming from its fixed manpower costs (maintenance and services), savings have been significant. “We are very pleased about the results,” says Peter Townsend, chief industrial engineer for Denison. “Only two of 50 supervisors have been let go for not co-operating.”

Denison, of course, is preparing for 1991 when the uranium supply contract with Ontario Hydro expires. Today the spot market price for uranium is about $18(US) per pound. But Denison is believed to be getting close to double that from its major customer, Ontario Hydro, as a result of long-term contracts.

Also, the workforce in Sudbury, Ont., has been drastically reduced in recent years. At Inco’s Levack mine, for example, the restructuring of jobs, by combining two or more responsibilities into one, has succeeded in reducing the number of man-shifts. This copper-nickel mine on the north rim of the Sudbury Basin has gone from producing 4,500 tons of ore a day in 1981 with 1,128 men to its current production level of 4,200 tons per day with 450 men.

Productivity in terms of tons per man-shift has doubled in the same period, according to Barry Nicholson, general foreman of safety. The following are some examples of job-restructuring at the mine: * — the skip hoistman is now the dumpman, who watches the skip being dumped; * — the shaft boss in the No 3 shaft can also perform cage-tending duties; * — members of the tram crew on the 1,600-ft level double as cage- tenders for lowering and hoisting supply trucks; * — the duties of the tippleman and crusherman were shifted to one man, who is also part of the tram crew; * — a shaft serviceman job was created, combining the responsibilities of shaft-inspector, cage-tender and pumpman; * — and the pour boss now utilizes the stope crew rather than having an additional pour man with him.

But not all productivity gains in the industry are being achieved by restructuring jobs. Technology is also playing an increasingly important role. For example, by simply installing some 66 new, wireless (500 kHz) radios on mobile equipment at its underground uranium mines in Elliot Lake, Rio Algom has achieved an estimated 3% increase in productivity over the past three years. Martin Eyres, of Rio’s Quirke mine, says that although the mine’s productivity increased by 10% during the period, the increased awareness (resulting from the radios) of the men underground probably accounts for about 3%.

The total cost of the radios was about $406,000 and maintenance amounts to about $750 per year per radio. Eyres says they have payed for themselves already. The manufacturer, El-Equip of France, which has offices in Elliot Lake, says it is working on the next generation of radios, the range of which will be extended to allow communication with people on surface.

Another trend which should contribute to operators’ awareness and comfort is the proliferation of underground lighting. At least one supplier, Harold Supply of Sudbury, is marketing a portable electric generator that powers an overhead, high-presure, sodium light and a high-intensity 12-volt spotlight. The 700-watt generator is powered by compressed air and can be easily connected to the mine’s air supply. It weighs just 70 lb and is extremely quiet.

One of the most evident trends in base metal mining technology in recent years has been the increasing importance of mining ore in pillars — rib, crown and sill pillars. More than 70% of ore production from the Lavack mine, for example, comes from mine pillars. And about 17% of Falconbridge’s total ore production in Sudbury comes from pillar recovery. As a result of the importance of this source of ore, it has become important to master the technique of mining next to cemented backfill.

At Inco’s Thompson mine, in northern Manitoba, 150,000 tons of nickel-copper ore is scheduled to be mined from six rib pillars and two crown pillars from the mine’s T3 complex over the next 1 1/2 years. The selection of the vertical retreat mining (vrm) method (as opposed to undercut-and-fill techniques) results in a cash flow differential of about $1.8 million, says Rod MacLean, divison supervisor at Thompson.

While development costs using vrm are higher and recoverable tons are lower than the undercut-and-fill method, the cost of labor and materials will be significantly lower. Moreover, efficiency in tons per man-shift is expected to be five times higher.

A nylon strap system used to support the log mat on the last undercut- and-fill lift has contributed significantly to the success of the crown pillar recovery program at Thompson, MacLean says. A 6-in-wide nylon strap bolted to the stope wall with 3/4 -in rockbolts on 6-ft centres along the length of the laminated stringers of the log mat lends added strength to the log mat which supports the cemented backfill above. The 20-lb straps eliminate the need for 200-lb wooden support posts. The straps have been used in Thompson since 1982.

At Campbell Red Lake Mines’ much deeper Red Lake gold mine, at Balmertown, Ont., high horizontal stresses combined with the brittle nature of the andesite host rock create rock-bursting problems when extraction of the gold ore exceeds 80%. So far, recovery of ore from the pillars requires that the ground be destressed first. According to Mike Neumann, former chief engineer at the mine, three attempts have been made to destress cut-and-fill crown and sill pillars and one attempt has been made in a shrinkage boxhole pillar. A violent rockburst, which occurred 30 seconds after one destressing round was fired, indicates that it was wise to have destressed this particular pillar, Neumann says. But destressing is often a very slow and costly procedure, the results of which are sometimes unpredictable. Campbell Red Lake used 1 3/4 -in holes drilled on 6-ft centres, straight up dip on this particular destressing blast. The holes were loaded with anfo (using a powder factor 20% of that required to break the rock) which was detonated using millisecond delays.

At Falconbridge in Sudbury, considerable research work has been done on the economics of mining up against cemented backfill compared to leaving a thin “skin” of ore behind. At the company’s mines in the Sudbury Basin dilution of ore caused by backfill getting into the muck has increased 40% from a low of 8% in 1981, according to William Hedderson, mines project engineer at Falconbridge’s Onaping operations. Research work is attempting to answer the question: How much capital should be put into keeping the fill walls standing given the fact that considerable capital has already been spent on design and on cement in the fill? Hedderson suspects that calcium leached from the fill reduces nickel recoveries in the company’s milling complex, although no research has been done to confirm the theory. The company is investigating ways to minimize peak particle velocities to 16 inches per second when blasting ore next to sandfill. It is also looking at ways to increase the tensile strength of the fill by adding high-strength layers of cement or synthetic fibres. Peak particle velocities of more than 16 inches per second have resulted in fill failure in the past. Computer models are being developed in co-operation with Queen’s University in Kingston, Ont., to help engineers predict the behavior of the fill.