Orebody Heterogeneity and Mining Scale


Bob McCarthy, SRK Consulting

Orebodies exhibit varying degrees of heterogeneity, where the valued mineralization is either concentrated in veins or bands or widely disseminated in stockworks or porphyritic intrusions. Barren gangue material exists as adjacent diluting material or as a matrix host to this mineralization. The spatial variation of the mineralized and gangue material in an orebody is a characteristic of heterogeneity that is not always exploited in developing a mine. At larger scales of heterogeneity, analysis of core hole data can be used to identify the selective mining unit (SMU) size, which in turn drives the sizing of mine equipment. Larger equipment with their economies of scale advantages are compared to smaller, more selective mine equipment in case studies. Full cost analysis is applied to determine whether ‘bigger is better’. These concepts are explained for careful consideration in planning a mining project.