Five months after entering production, the Silidor gold mine lying just outside of this city has reached its planned production capacity of 33,000 tonnes per month. The mining operation, officially opened Sept. 7 by owners Noranda (TSE), Cambior (TSE) and Nova-Cogesco Resources (TSE), wasn’t scheduled to reach its production capacity until late in the year or the beginning of 1991. As reported (T.N.M., June 18/90) following a site visit, the mine entered production at the first of April.
About 325 invited guests attended the opening ceremony on a mainly sunny, reasonably warm northwestern Quebec day. The crowd gathered under a large canopy for the speech presentations, then watched the unveiling, in the open air, of a 1-tonne Silidor rock specimen (grading 10 grams per tonne) and plaque commemorating the occasion.
Noranda, with a 55% interest in the project, acts as the operator through an affiliated company, Mines Silidor Inc. Cambior has a 25% interest in the project and Nova-Cogesco, moving into the ranks of a gold producer for the first time, a 20% interest.
For Cambior, based in Val d’Or, Que., the opening marks the company’s third gold project to enter production in three years. Still another Cambior gold project, the Mouska deposit in northwestern Quebec, is scheduled to enter production in June, 1991.
The Silidor mine, which will produce about 60,000 oz. gold this year and about 73,600 oz. in 1991, does not include a milling operation. Noranda transports its share of the ore to its nearby Horne smelter for processing, while the Cambior and Nova-Cogesco shares are shipped 20-25 miles to Cambior’s Yvan Vezina mill for treatment.
Among the speakers at the opening ceremony were Michel Lefebvre, vice-president of Mines Silidor and a vice-president of Noranda Minerals; Raynald Vezina, Cambior’s vice-president operations; and Mario Caron, president of Nova-Cogesco.
Discovered in late 1985, the Silidor mine hosts reserves of 4.78 million tonnes grading 5.4 grams per tonne. Estimated life of the mine, at the planned production rate of 400,000 tonnes per year (1,500 tonnes per day), is 12 years. Cost to the three partners to bring the mine into production was about $56 million, including $24 million for exploration.
Mine manager Claude Begin said the mine is operating at a production cost of $40 per tonne (about US$200 per oz.). The grade of the ore being mined, at the time of the official opening, was about 5.2 grams per tonne and rising, reflecting the shift from development muck to stope material.
The Silidor deposit comprises several facies, including a tonalite, a mafic dyke, a carbonated breccia and a quartz vein. The quartz content of the mineralization is an added benefit for Noranda, which can use the material as a flux in its Horne copper smelting operations.
The orebody dip varies between 55 degrees at the northern end and about 70 degrees at the southern extremity. The orebody is described as being 900 metres in length with an average width of four metres. (The vein is wider on the northern side.) The deposit is open at depth.
The current mining method is long-hole stoping, which will probably give way to the shrinkage method as the vein narrows on the southern side of the deposit. Ore is currently being extracted from above the 220-metre level.
The mine is serviced by a 4-compartment shaft sunk to about 545 metres. (Three of the compartments are active; the fourth compartment was built to allow for future shaft sinking if required.) A service ramp has been dug to the 220-metre level.
The mine currently employs about 120 full-time workers.
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