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GOLD association with quartz veins, in finegrained pyrite and in association with amorphous carbon. High-grade gold mineralization occurs within quartz veins contained in prominent alteration zones that provide a well-recognized exploration target here. A number of separate orebodies have been identified, including the North, North A, North B and West. In the West zone, around 90% of the gold is associated with disseminated sulphides, mainly pyrite, with minor arsenopyrite, pyrrhotite and chalcopyrite. The North A zone, by contrast, is centered on a prominent quartz vein that contains visible gold, with a surrounding alteration zone hosting disseminated sulphides that carry around 30% of the gold in this zone. Overall, there is a direct association between the gold and sulphide grades, explained mine geologist Ivan Langlois. "The more sulphides, the higher the gold grade," he said. The company is now drilling to better define North A's potential at depth, with drill drifts established on the 535 m and 610 m levels to give access to the structure down to 1,000 m. According to Langlois, North A Deep is separated from the main section of the zone by a barren shear zone, with North A Main bottoming out at around 420 m depth, and North A Deep only beginning some 25 m below that. the North A, and from 460 to 475 m in the North A Deep. The ore zone here runs up to 3 m wide, allowing longhole stoping on 15 m-high sub-levels, with a strike length on the 445 m-level of about 35 m. However, as Langlois told E&MJ;, by the time the mineralization reaches the 580 m level, the ore zone is some 150 m long, with clear indications that the orebody becomes more extensive at depth. The mine relies largely on Atlas Copco LHDs and trucks for its production. A 2-yd3 ST2G is used to move broken ore from the stopes to a transfer point on the ramp, where larger 6-yd3 and 8-yd3 machines load it on to the mine's fleet of three, 42-mt-capacity MT42 trucks for the haul to surface. Bell Creek is also taking delivery of an MT50 truck to compensate for increased haul distances, the ramp having been developed large enough to handle this size of machine. For drilling, the mine has a number of Atlas Copco Boomer drill rigs for development, while contracting out its stope work to Taurus Drilling, which uses its own specially designed longhole rigs. Optimizing the Mill Given its dependence on the mill to handle ore from both Bell Creek and Timmins West, the company's plans have centered on increasing throughput again to 3,000 mt/d, which has involved building a new crushing plant, 6,000-mt-capacity fine ore bin, SAG mill, carbon-in-leach tanks and a new thickener. While its initial schedule envisaged achieving this by the end of 2012, the program was later revised to give a staged expansion, initially to 2,500 mt, then to 3,000 mt in the second quarter of this year in line with the increasing availability of ore from the two mines. Meeting the 2,500-mt/d target by the end of 2012 involved upgrades to most of the recovery section of the mill. The new thickener and water-handling system was commissioned in October, followed by the CIL tanks, a leach tailings screening plant and pump and piping upgrades to the secondary grinding circuit. The second stage, to achieve 3,000 mt/d, is focusing on the mill's ore receiving, crushing, storage and grinding sections. Overall, the company expects the expansion to cost just over C$100 million to complete, compared with its initial C$83 million estimate, although its rescheduling has helped to minimize the overall increase. At the other end of the plant, the bullion room produces roughly 85% doré bars that are shipped to Johnson Matthey in Mississauga for refining. Recoveries have improved steadily as the mill has run at regular rates, and were standing at over 97% in late 2012, while per-ounce cash costs Ramp Development Preferred During its previous period of working, the mine was accessed solely by its 300-mdeep vertical shaft. Today, the headframe still overlooks the mill and other surface facilities, but access and all of the production is handled through the ramp that Lake Shore began developing from surface in May 2009. A separate vent shaft supplies 146 m3/s (310,000 cfm) of fresh air into the mine, with the ramp acting as the main return. Eighteen months later, the ramp had reached the 320 m level, allowing access to the mineralization beneath the old workings for the first time. By September 2011, it had been extended to the 460 m level, below the top of the North A Deep zone, and at the time of E&MJ;'s visit it was down to 565 m and the 535 m-level hanging-wall exploration drift was in full use for drilling the structure down to 775 m. By the end of 2012, the ramp had been extended to 610 m below surface. Two stoping zones were in operation in October 2012, between 300 and 320 m in 32 E&MJ; • FEBRUARY 2013 Pouring a doré bar at the Bell Creek mill. The company expects cash costs to fall once mill output stabilizes at 3,000 mt/d. (Photo: Simon Walker) www.e-mj.com