Giant Bay tests bioleaching in several joint ventures

Bullish about prospects for bioleaching refractory gold ore, Giant Bay Resources has entered a number of joint ventures to test the process commercially.

Teaming up with Wright Engineers in November, 1987, Giant Bay formed a joint venture company, International Bioleach Inc., to offer a turnkey package of biotechnology know-how to the mining industry (N.M., Dec 7/87). The company is evaluating six projects using bioleaching methods. The technology’s commercial viability was proven last summer when a 10-ton-per-day bioleach demonstration plant was operated for Giant Yellowknife at its Salmita mine in the Northwest Territories. Where conventional cyanidation gave 65% to 70% recovery, bacterial leaching followed by cyanidation gave 95.6% recovery.

Another joint venture with Wright Engineers is looking at resurrecting the much-troubled Lad ner Creek gold mine of Carolin Mines near Hope, B.C. The companies are funding a $600,000 program of evaluation and metallurgical tests which should be completed by mid-February, when a full feasibility will be considered. Giant Bay President Claus Jensen explains that emphasis is being placed on initial production of 860,000 tons of tailings grading 0.05 oz gold per ton. He suggests that bioleaching will not be used for processing the tailings, but could still benefit the over-all operation.

If the program is successful, the feasibility will be funded by Carolin, followed by redesign and rebuilding of the mill. The Giant Bay/ Wright joint venture will act as operator and after payback will receive 15% of cash flow plus a management fee.

On its own, Giant Bay is involved in several other projects to evaluate the technology. A production royalty agreement with Levon Re sources and Veronex Resources gives Giant Bay 8% of operating profit if tests indicate a bioleach plant will assist in processing the refractory sulphide ore at their Congress gold property in the Bralorne area of British Columbia. Laboratory results have been positive and feasibility studies are under way. Current planning is for a 250- to 300-ton-per-day operation, resulting in projected gold production of 25,000 to 31,000 oz per year.

In a joint venture with Hecla Mining Co., Giant Bay has the right to acquire a working interest in the Stibnite, Idaho, property should bioleaching be used for processing the ore. Substantial bench scale testwork has been completed and a bulk sample will possibly be tested this spring.

Another joint venture agreement is with Sandhurst N.L. for the purpose of commercializing the processing in Australia. Jensen believes the potential for bioleach ing in Australia is significant and six properties suitable to bioleach ing are being tested.