Influence of particle shape on slurry wear of white iron

Slurry particle shape is an important variable in determining equipment life in mineral processing operations, especially in the grinding circuit. Slurry particles here are generally coarse, sharp and at high concentrations. Little information is available to guide practitioners in measuring particle shape or understanding the impact of particle shape on the wear rate of the hard white irons that are commonly used in processing equipment. The first part of the current work has explored the differences between 2 methods of measuring particle shape - Circularity Factor (CF) a ratio of the perimeter to projected area of the particles and spike parameter (SPQ) which is an analytical method of fitting triangles to the prominent features of the particle outline. Calculating the CF and SPQ for a wide range of particle shapes (from angular to round) found a close linear correlation between the two. This was surprising given that the more complex SPQ methodology was developed to improve particle shape characterisation. The second part of the work used a large scale Coriolis tester to determine the effect of particles of different shape on the wear rate of white cast iron. To simulate the type of wear experienced in grinding circuits a range of different particle shapes with similar CF to those observed in field applications were tested. Coarse silicon carbide, alumina and silica sand particles were individually run through the Coriolis tester. By recirculating the particles in the rig, the shape became more rounded (with CF eventually spanning the range seen in field applications) without dramatically impacting particle size. An inverse power law relationship was found between the CF and the erosion rate for white iron. This correlation should be able to be used to determine the impact of changes in CF on equipment wear life. A third element of the work was a microscopic investigation of the worn sample surface from the Coriolis tester to identify changes in wear mechanisms with particle hardness and shape. In addition a comparison was made with worn slurry pump parts to ensure that the mechanisms of wear from the Coriolis test were representative of those seen in equipment in the field. (C) 2015 Elsevier B.V. All rights reserved.