POLAR PRODUCERS LUPIN

It would seem that Lupin’s cost- cutting endeavors are paying off. In 1988, the mine produced more than 190,000 oz of gold at a cash production cost of about $200 per oz. (Costs increased slightly from the previous year because of higher operating costs associated with shaft-deepening and because of the stronger Canadian dollar.) Every day roughly 1,690 tonnes are mined from the orebody.

Published ore reserves at the beginning of 1988 were 3.4 million tonnes of proven plus probable ore grading 11.38 g per tonne (or 3.7 million tons grading 0.332 oz per ton).

Since start-up in 1982, Lupin has taken its place among the most important gold deposits in Canada. Past production plus current reserves total about 2.15 million contained ounces (67 million g) at an average grade of 0.332 oz per ton).

The orebody has three zones, which fold to resemble a “Z” shape. All three zones were recently being mined. The Centre and East zones are wide enough to allow long-hole open- stoping, which is the primary mining method used owing to the orebody’s long strike length, large width and vertical dip. Two other methods are required for the narrower West zone — raise platform mining and modified long-hole open stoping (so-called because smaller-sized production and development drill rigs are used in the stopes). Currently more than half of all muck is coming from the Centre zone.

The ore grade, which averages 0.324 oz gold per ton (11.1 g per tonne) is relatively high compared with most gold mines in Canada. Grade is normally highest near the north nose of the Centre zone.

The Lupin mill consists of eight circuits: crushing, grinding, pre- aeration, leaching, filtration, precipitation, refining and tailings. The average recovery is about 95%, which amounts to about 520 oz of gold recovered per day.

The mill has reached its potential under manual operating conditions. However, the recent installation of computer-based process controls is succeeding in improving efficiency while cutting production costs. “The system will probably save the company more than $340,000 a year,” Mill Superintendent Peter Parashyniak told The Northern Miner Magazine on a recent visit. “Lime additions have been reduced by approximately 10%, cyanide by 6% and grinding media by 10%. Also, manpower has been reduced by two — eventually four — operators.”

The fundamental advantage of the system is that it allows operators to correct any concentrating mishaps before they occur, thereby stabilizing the circuits.

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