Experimental study on the stereological bias in surface exposure measurement of ore particles

Abstract

In mineral processing, surface exposure, in which the particle surface is composed of one phase, is important, because the extent of the surface exposure determines the efficiency of floatation. In general, surface exposure is calculated based on two-dimensional (2D) measurement of particle sections. However, such 2D measurement is known to result in a form of error called stereological bias. The stereological bias associated with surface exposure has not been thoroughly studied. In this study, as a means of empirically validating the findings of a previous, numerical study, the stereological bias involved in measuring the surface exposure of binary particles was experimentally investigated using artificial particles and X-ray CT analysis. Three types of binary particle samples were utilized, and significant stereological bias in surface exposure measurement was observed in each case. Then, the effect of particle shape (aspect ratio for the global shape, and corrected sphericity for the surface roughness) on the stereological bias was investigated. It was confirmed that the effect of particle shape was negligible compared to the effect of the internal mineral structure of the particle. This result supports those of the previous, numerical study.