Numerical analysis of the general characteristics of stereological bias in surface liberation assessment of ore particles

Abstract

In mineral processing, ground ore particles containing valuable minerals are commonly separated from the gangue by flotation. For efficient flotation, surface liberation, in which the particle surface is composed of one phase, is important. Surface liberation is commonly measured by two-dimensional (2D) measurement of particle sections of resin-mounted samples. Such 2D measurement is considered to result in a form of error called stereological bias; however, the stereological bias associated with surface liberation assessment has not been fully studied. A series of numerical simulations was here conducted, to investigate the influence of a particle’s texture (the 3D internal particle structure) and shape on such stereological bias. First, a total of 110 patterns of texture (10 patterns of grain size times 11 levels of grain content) were modeled, to determine the general characteristics of the stereological bias. Then, the influence on the stereological bias, of particle shape as represented by the aspect ratio (an index of global shape) and corrected sphericity (an index of surface roughness), was investigated. The results revealed that texture had the largest, aspect ratio the second largest, and corrected sphericity the smallest influence on the stereological bias in surface liberation measurement. Based on the results, it is suggested that a rough estimate of the stereological bias in the measurement of irregularly shaped real ore particles can be made from much simpler numerical models of spherical particles.