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Mining Operations
The Kemess South open pit has a conventional mine plan with 15 metre benches and
45 degree wall angles. Two electric cable shovels, a hydraulic shovel and a loader supply ore and waste to the fleet of 15 Euclid haulage trucks, which move ore to the primary crusher and waste rock to storage piles. Current mining capacity is approximately 50 million tonnes/year, 19 million tonnes of which is ore.
Milling Operations
Hypogene, supergene and leach cap ores are processed using conventional crushing, grinding and flotation techniques to produce gold-copper concentrates with a minor by-product silver value. Based on a nominal production rate of 50,000 tonnes of ore per day or 19 million tonnes of ore per year, average annual metal production is forecast to range from 250,000 – 300,000 ounces of gold and 65 million – 75 million pounds of copper contained in 145,000 tonnes of concentrate.
Run-of-mine ore is crushed by a primary gyratory crusher located adjacent to the open pit. Crushed ore is conveyed to a stockpile and fed to two parallel grinding circuits, each operating at a nominal rate of 26,000 tonnes per day. Each grinding circuit consists of one semi-autogenous grinding mill and one ball mill in combination.
Rougher flotation consists of four parallel rows, each with seven flotation cells. Rougher concentrates are reground before being upgraded in two cleaning stages. Cleaner concentrates are pumped to a concentrate thickener and then to two plate filter presses, which reduce the moisture content in the final concentrate product to approximately 8% by weight.
Mill tailings are pumped through one of two parallel pipelines to the tailings impoundment facility located in the South Kemess valley, seven kilometres from the mill. A zoned, earth-filled embankment dam constructed across the valley permanently contains the tailings. In order to accommodate tailings from each subsequent year of production, the height of the dam is increased annually using locally sourced construction materials with very specific properties. The dam’s core is supported with millions of tonnes of clean, coarse sand that is extracted from the tailings in the cycloning and depyritization plant that began operating in 2002.
Design engineering, as well as quality assurance and quality control during construction of the tailings impoundment, is performed by an independent consultant and reviewed further by an independent panel comprised of three industry experts.
Concentrate Marketing
Kemess gold-copper concentrate is trucked in bulk approximately 380 kilometres by gravel road to a rail spur at Mackenzie, BC. Kemess concentrate contains 20 – 25% copper and
50 – 150 grams per tonne of gold.
Concentrate is currently sold to Xstrata PLC and is transported by rail to the Horne smelter in Rouyn-Noranda, Quebec for smelting.
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