Process Selection, Design And Commissioning Of The Rawas Gold Project, Indonesia

The Rawas Gold Project in Indonesia has a high silver ore with a ratio of approximately 25:1 Ag/Au. Four process flow­sheets were considered during the development phase, ie. full Merrill Crowe, CIP, CIP with zinc cementation of eluate and a hybrid Merrill Crowe - CIP circuit. The process plant was constructed using a CIP circuit with zinc cementation of eluate. Unusual aspects of the design include an elution circuit designed to strip three batches of car­bon per day and an elution column designed to operate with either upward or downward solution flow. Significant improvements implemented since starting up the plant include the use of local materials and labour for relining the mill, a change from lime to caustic soda for pH modification and the elimination of caustic soda dosing to the elution pre-soak step.