AGG plans to develop the Kobada Project in two stages. Both stages utilise similar processing technology. Stage 1 aims for the most effective use of pre-production capital expenditures while Stage 2 aims to optimise operating efficiencies (and hence operating expenditures).
Stage 2 is to target the production of more than 50,000 Au ounces per annum by processing 1.6 million tonnes of ore per annum.
The plan is to focus predominantly on the saprolite ore types. The aim is maximising throughput and gold recovery in order to maximise operating efficiencies and profit margins.
The processing concept is simple, with crushing of harder ore types (laterite and quartz) to -2mm before scrubbing, pre-concentration and gravity concentration. The run of mine ore feed to the plant is reduced to a bulk concentrate of around 2% of the original feed mass. This concentrate is expected to contain around 86% of the gold, which is then liberated by traditional grinding and leaching techniques.
The inclusion of the leaching circuit allows for the treatment of greater volumes of concentrate, which means that the process can achieve greater gold recovery.
In gravity separation of Kobada ores, there is a direct correlation between the amount of concentrate produced and recovery. That is, allowing more of the material to pass to the concentrate means more of the gold will also pass to the concentrate.
The ball mill and leaching circuit allows for the efficient treatment of this concentrate prior to electrowinning and smelting.
AGG anticipates gold recoveries of around 85% with this technology. Further information can be found in the Preliminary Economic Assessment from November 2014.