The process involves working with project geologists to obtain knowledge of the geology. Based on this understanding a lithological, spatial and/or mining schedule sample selection program is developed.
Dependent on the sample source, (whole rock, PQ, NQ or HQ core, half or quarter core samples) a testwork program is developed to characterise the comminution properties of the ore and assess variability.
OMC typically uses the JK Drop Weight Test and a suite of bond based laboratory tests to characterise the ore.
The following tests are typically undertaken as part of the program and are outsourced to independent metallurgical laboratories worldwide:
The testwork results obtained from this suite of testing are particularly useful when compared to other ore types with known comminution behaviour in the OMC database. The extensive database, compiled from 30+ years of testwork results, surveys and circuit performance data, provides strong guidance on the most appropriate circuit for a given ore. The results also provide input to OMC’s power based and JK SimMet modelling for major equipment selection.
Variability modelling can typically be undertaken on samples with a top size as small as quarter NQ core with the modified SMC test and Ball work indices. These tests identify the high and low energy breakage characteristics of the samples. Results, in combination with a mining schedule, can be used to assess plant production over the life of mine. The variability of testwork results is analysed and additional testwork is sometimes recommended to reduce design risk.