Bioleaching gold process considered an alternative

A bioleaching process developed by Giant Bay Resources for treating refractory gold ores can be considered an “attractive alternative” to roasting or pressure oxidation as process alternatives for the treatment of refractory gold prior to cyanidation, according to a Vancouver engineering firm.

Wright Engineers completed a capital and operating cost comparison of pressure oxidation, roasting and bioleaching as process alternatives, with bioleaching data obtained at a Giant Bay demonstration plant at the Salmita gold mine of Giant Yellowknife Mines in the Northwest Territories. Wright executive Robert Pendreigh said at a press conference in Burnaby, B.C., that their cost comparisons were made at the Salmita site and at a hypothetical site in northern Nevada.

In both locations, he said, bioleaching had the lowest capital cost and lowest operating cost per ton of ore, of the three process alternatives. During the demonstration plant run at Salmita (from June 25 to July 10 this year), the gold recovery using bioleaching was 95.6%.

Commenting on the Giant Bay development, Kent Morton, technical projects supervisor for Giant Yellowknife Mines said “it is clear that the bioleaching technology Giant Bay has developed will play an important role in precious metal recovery from refractory ores. Giant Yellowknife has been producing gold from such ores for almost 40 years now and we recognize the significance of this development.”