Particle size distribution for copper heap leaching operations as established from 3D mineral exposure analysis by X-ray microCT

摘要

The particle size distribution (PSD) for copper heap leaching is an important consideration in the design and operation of any copper heap leaching facility. High-resolution 3D X-ray microtomography (XMT) can be used for the direct determination of the percentage of exposed valuable mineral grains in multiphase particles which vary in size from 40 mm down to a few hundred microns. For cone-beam CT, a whole 3D data set is acquired with only one rotation of the sample. Clearly, cone-beam CT has the best prospects for true 3D exposure analysis of packed particle beds and is able to provide the necessary accuracy to quantitatively describe the 3D distribution of micron-sized mineral grains in multiphase particles. Using recently developed software, microCT data can be used to determine the fraction of mineral exposed and thus estimate the extent of recovery. XMT technology consists of examining the degree of mineral exposure for each size fraction in 3D, then, with the use of algebraic calculations, the extent of recovery can be estimated for different particle size distributions. To confirm the usefulness of such mineral exposure analysis, column tests were performed using three PSDs for three samples of ore composites obtained from the copper heap leaching operation at Zaldivar-Chile.