Development of ultrafine grinding at Kalgoorlie Consolidated Gold Mines

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultrafine grinding (UFG) plant to supplement its existing roaster-concentrate treatment capacity. The process involves the fine grinding of refractory pyritic concentrate to 10 mum followed by direct cyanide leaching for gold recovery. By this means, gold can be economically extracted from the concentrate without the need to first oxidize the host pyrite. This paper details the history of the project from the initial laboratory test work that compared possible treatment options to the present day performance of the actual 12-t/h plant. Areas discussed include capital and operating cost comparisons of the major treatment options, laboratory and pilot-scale UFG performance, UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.