OMC’s scope of work was to assess, supervise and optimise comminution testwork (scrubbing in particular) for various ore blends. Based on the testwork results, a suitable comminution circuit was then sized.
Three circuit options were considered as possibilities; Secondary Crush – HPGR – Ball Milling; Tertiary Crush – Ball Milling; and Secondary Crush – Ball Milling.
The samples tested for Mumi Sulphides were among the most competent in OMC’s database (in the top 10%), but had well below average grinding indices. As such, SAG milling was found to be a very inefficient circuit option from an energy perspective.
The Secondary Crush – HPGR – Ball Milling option was the most efficient from an energy perspective, but posed some significant cost issues associated with maintenance of the HPGR’s. Secondary Crush – Ball Milling was significantly less power efficient than the other two options due to the issues with high ore competency. It was also the least elegant from a design perspective. Tertiary Crush – Ball Milling was the OMC recommended circuit option. The study is currently still in progress and further testing is underway to validate the extreme competency of the ore.