The MKD5 nickel sulfide orebody at Mount Keith, Western Australia, is one of the world’s lowest-grade operating Ni mines and currently the largest Ni producer in Australia. The mineralogy and metallurgical properties of MKD5 low-grade, disseminated ores are complex and consequently have required detailed characterization combined with innovative processing and mining in order to achieve economic metal recoveries and concentrate quality. Most of this complexity relates to the effects of hypogene and supergene alteration of the ultramafic protore, and consequent modification of both gangue and sulfide mineral assemblages. A multidisciplinary approach has been taken in order to optimize the resource modeling, mining and processing of the MKD5 orebody, including the development and use of an integrated geometallurgical (GEOMET) model to predict key processing parameters, steps taken to minimize the impact of deleterious contaminants, and the development of a concentrate quality predictor. The design of the Mount Keith concentrator flow sheet presented significant technical difficulties, mainly relating to high pulp viscosities and reagent consumption which were a direct result of the tendency of the ore to generate high levels of slimes during comminution. This was overcome by the development of a unique, two-stage desliming circuit. The recovery improvements developed by a specialist team have resulted in a 13 percent increase in Ni recovery, and increased the net present value of the MKO by A$300 M.

Significant advances continue to be made which promise to enhance further the capacity, product quality, and cost effectiveness of the operation. These advances are once again the result of an interdisciplinary team-based approach. Such an approach is necessary in the current business environment given the rapid progress of mining and processing technology and is particularly important in the case of an operation such as that at Mount Keith, because of the very low grade nature of the resource.