:: Bogoso BIOX^® Incorporates Knelson Concentrator

The Bogoso/Prestea Gold Mine (90% owned by Golden Star Resources ltd.) in Ghana is the latest bio-oxidation plant to incorporate a gravity circuit as an integral part of their process flowsheet.

Biomin, a subsidiary of Goldfields Ltd., has been selected to supply their proprietary BIOX^® process for the project. The gravity concentrator is a custom made 100% stainless steel model KC-XD30 that will treat the washed BIOX^® residues after a 3 stage counter current decantation circuit. The KC-XD30 concentrator will recover a high proportion of the liberated gold prior to discharging to a conventional CIL circuit.

At full production, expected in late 2007, Bogoso/Prestea’s sulfide circuit will operate at a design capacity of 3.5 million tonnes per year of refractory sulfide ore into the crusher, equivalent to 34 tonnes per hour of concentrate through the BIOX^® circuit. Design recovery is estimated at 85% overall, resulting in annual gold production from the sulfide plant of between 230,000 and 260,000 ounces.

Once operational the Bogoso/Prestea bio-oxidation plant will be the tenth BIOX^® installation in the world and the fifth to include Knelson technology. The others include Fairview in S. Africa, Sao Bento in Brazil, Anglogold Ashanti in Ghana and Beaconsfield in Australia.