Processing of ore at Golden Grove begins at the run-of-mine (ROM) pad, where it is fed into a crusher. Here, the ore is crushed from approximately 300 millimetres into pieces of approximately 100 millimetres.
The ore is then carried along a conveyor and stockpiled. Stockpiled ore is taken to the mill where it is broken down further using a two-stage wet grinding circuit that includes a primary semi-autogenous grinding (SAG) mill and secondary ball mill, cyclone cluster and a pebble crusher to treat oversize material from the SAG mill. This circuit grinds the ore into a fine slurry of approximately 100µm (micrometre) particles..
The ore then undergoes a flotation process which separates the valuable minerals as a froth from unwanted material, the leftover ‘tailings’ slurry.
The watery concentrate froth is then thickened into a slurry form which resembles a thick liquid or paste, of about 35% solids. After thickening, the concentrate goes through a dewatering process where most of the water is removed from the solids so that what remains is a metal concentrate in powder ‘dry’ powder form (~9% moisture).
Concentrates are stored at Golden Grove prior to being transported via truck to the Geraldton Port. At the Geraldton Port, concentrates are transferred in an enclosed storage shed prior to ship loading and export.
Three storage facilities have been constructed at Golden Grove to contain tailings produced during processing over the life of mine.
The first two storage facilities have been decommissioned and remaining process water evaporated. An erosional cover is also in place, where appropriate, to prevent dust generation.
Golden Grove is now utilising the third facility, which has sufficient capacity for remaining mine life.
Planning is also underway for long-term encapsulation of all three facilities.