Roadheader in use at New Bousquet No. 1 — Lac testing

The Bousquet No. 1 gold mine might be considered the poor cousin of the three mines owned and/or operated by Lac Minerals (TSE) in the Malartic area of Quebec.

The Doyon, owned 50% each by Lac and Cambior (TSE), reported total gold production in 1992 of 254,700 oz., while Bousquet No. 2, wholly-owned by Lac, yielded 175,884 oz.

By comparison, Bousquet No. 1, also wholly-owned, turned out 63,036 oz. last year.

Cash costs in 1992 followed a similar pattern: US$218 per oz. at Doyon and US$186 at Bousquet No. 2 compared with US$338 at Bousquet No. 1. Despite these gross disparities — or perhaps because of them — Lac’s operations and research staff are pulling out all the stops at Bousquet No. 1. The company is determined to turn this mine around. And, in so doing, they will be moving Canadian mining into the 21st century.

The root of Bousquet No. 1’s problems are poor ground conditions and a structurally weak orebody. The mineralized areas are essentially zones of narrow quartz-stringers interleaved within finely laminated sericite schist. The laminations are like the leaves of a book. Once an opening is made in the schist, as for example by a stope, the book opens, the folia separate from one another, peel away and break off.

Yves Fourmanoit, recently appointed general manager of the Bousquet complex, put it in a nutshell: “We have one year of reserves left at Bousquet No. 1 or we have 10 years. It all depends whether or not we can mine in a cost-effective manner.”

Test work suggests a 10-year life is all but a foregone conclusion. And the key is the Dosco Roadheader.

This machine is a continuous miner. Instead of breaking rock by drilling and blasting, the roadheader uses its massive 50-ton weight and 160-hp rotating cutter-head to gnaw and rip the rock from the solid. (It functions in much the same manner as a carpenter’s drill cutting into a slab of wood. The cutting, however, is four feet long, two feet in diameter and set up with 58 replaceable tungsten carbide teeth.)

The operation is a marvel to watch. The rotating cutter-head chews out a 2-ft.-diameter hole in the rock, two feet deep, and in not much more than a minute. The operator then ranges the head in an ever-increasing radius from the initial opening until the outermost limits of the drift are reached. The operator then repeats the process. Dust is kept to a minimum by water sprays. An air curtain separates the operator’s atmosphere from that at the drift face and an exhaust ventilation system ensures particulate matter is drawn into the ventilation duct rather than dispersed into the general atmosphere. Cutting rates are dependent on the strength of the rock and so far have averaged about 230 tons per shift.

Lac has had the roadheader on trial since August, 1992, operating it in a range of rocks of varying strengths and structures. Identical machines have been used in the “soft” sedimentary rocks of the coal measures for many years. Lac’s usage marks one of the few occasions it has been applied to the harder, more abrasive rocks of the average Canadian metal mine. All indications are that Lac will be using these machines for regular production — certainly at Bousquet No. 1. and possibly within the next 12 months. It is also possible that a roadheader will be used at Doyon, where one of that mine’s smaller zones has proved difficult to mine by conventional means.