MUSSELWHITE

PROCESSING

The milling facility uses two-stage crushing to reduce ore to minus 19 mm and conventional two-stage rod-ball grinding to further reduce ore to 80% passing 106 microns. Two Knelson concentrators extract liberated gold particles that are treated in an Acacia Reactor in an intensive cyanidation process. A high-grade gold-bearing solution reports to electrowinning. Between 26% to 30% of the gold is extracted with this process.

Conventional whole-ore cyanidation is used to further extract gold from the ore. This leaching is done in four stirred-tank reactors. About 93% of the remaining gold is extracted. Gold is recovered from leach solution using activated charcoal or carbon in a six-tank CIP circuit. This process is 99.8% efficient. The tailings or residue from this process is washed with incoming reclaim water in a two-stage counter-current decantation circuit and then treated for cyanide removal using Inco’s sulphur dioxide technology. The mill tailing product is discharged to the impoundment containing less than 1.5 mg/L cyanide.

Gold is removed from the gold-laden carbon in an elution column using a caustic-cyanide solution at high temperature and pressure. The resulting gold-bearing solution reports to electrowinning where gold is deposited onto stainless steel cathodes by electrolysis. The combined elution and electrowinning process is 99% efficient. Gold is washed from the cathodes, filtered, dried and melted in a furnace to produce gold metal. Overall, gold recovery from start to finish is 95.5%. 

Simplified Mill Process Flowsheet