Evaluation of Metallurgical Recovery Factors for Diamonds Recovered from Kimberlites

Abstract

Extraction and recovery of diamonds requires that the host rock, kimberlite, is fragmented to liberate and recover the contained diamonds. Optimal recovery requires trade-offs to be made between maximising liberation, minimising diamond breakage or loss and cost of recovery. Effective fragmentation and recovery are not only dependent on the comminution and recovery techniques used but are also a function of the interactions between the diamond characteristics, the host rock properties and the technology used to crush the kimberlite and recover the diamonds. Prior approaches have been limited by a disregard for these relationships and how they change in response to variable kimberlite and diamond characteristics and their impact on diamond recovery. Incorrect recovery estimation impacts negatively on the evaluation, design and operation of diamond mining projects. This research develops and demonstrates methods to collect and spatially estimate relevant orebody characteristics that impact on diamond liberation and subsequent recovery. These characteristics are used in an integrated value chain model to quantify the variability and uncertainty of diamond recovery. The use of this technique is demonstrated in two case studies. The benefits of this approach include improved evaluation of diamond projects, development of better design and operational strategies and will improve not only the resilience of individual diamond projects, but also the performance and economics of the diamond mining industry.