Madeleine evaluates autoclaves

Toronto-based Madeleine Mines (TSE) is experimenting with a hydrometallurgical process designed to recover palladium-platinum, gold and base metals from its Lac des Iles property near Thunder Bay, Ont.

To avoid the high cost of taking concentrates to smelters in the U.S. and Ontario, Madeleine plans to install three autoclave units right at the open pit mine site, said President Dale McDoulett, during the company’s recent annual meeting in Toronto.

Now held 32% by Kaiser- Francis Oil of Oklahoma, Madeleine owns 50% of the 7,619-acre Lac des Iles property where probable reserves stand at 7.4 million tons of grade 0.1% copper, 0.1% nickel, 0.18 oz. platinum group metals and 0.01 oz. gold per ton. The other 50% is held by The Sheridan Platinum Group, a private company owned 90% by Boston Bay Mines (CDN), which in turn is held 40% by Belleterre Quebec Mines (CDN).

Used extensively in South African platinum mines and by some gold producers in the U.S., autoclaving involves the use of high temperatures and high pressure to oxidize sulphide ores and (or) concentrates before they are refined.

American Barrick Resources (TSE), for example, is successfully using autoclaves to process refractory gold ores at its Goldstrike mine in Nevada at a rate of about 8,000 tons per day.

As smelting charges can be as high as 50-60% of the value of the ore, McDoulett said the company would be in a position to use the amount saved to cover other costs involved in running a 3,000-ton-per-day mine. Bench-scale tests are being conducted on some of the 500-600 tons of concentrates now sitting at the mine site and if everything goes according to plan, Madeleine will set up three 6,000-gallon, glass-lined autoclave units at a cost of roughly $75,000 per unit.

“If the hydrometallurgical process works, the mill is ready to start and it would be just a matter of getting a crew up there,” said McDoulett when asked how soon the mine could be in production. He said the company should be in a position to make a definite announcement in the fall.

By that time, Madeleine shareholders may be asked to vote on a proposal to split the company into separate entities, one to hold the Lac des Iles platinum project and the other to retain 25% of a small gold mine in Honduras.

Shareholders at the annual meeting were prevented from voting on the proposed split, because shares of the new company, Lac des Iles Platinum have yet to be registered with the Securities and Exchange Commission in Washington, D.C. If the reorganization is approved, Boston Bay and Belleterre Quebec will be able to swap their Sheridan Platinum shares for shares of Lac des Iles Platinum.