The Use of 3D X-Ray Computed Tomography for Gold Location in Exploration Drill Cores

Abstract

Three-dimensional computed tomography (3DCT) is a non-destructive characterisation technique that was applied to the study of gold-bearing ore from the Witwatersrand Deposit, South Africa. The ability to pinpoint gold occurrence prior to downstream comminution and leaching would potentially reduce processing costs. The aim of the study was therefore to determine to what extent gold, typically fine-grained in occurrence, could be identified in situ. Two gold-bearing drill core pieces were investigated using 1-mm focal spot X-ray tomography and micro-focus X-ray tomography (μXCT). Using the derived data, the cores were physically cut and polished for examination by conventional automated scanning electron microscopy (SEM) to detect gold grains. The SEM results were then compared against the μXCT data. Gold was, to an extent, located by μXCT and validated against SEM data. These first findings suggest that areas rich in gold can be pinpointed by 3DCT prior to conventional assessment, hence potentially reducing processing costs.