Effect of ore heterogeneity on the ball mill wear rate during a grinding process at gold mines of Saudi Arabia (KSA)

Abstract

Purpose. The current research aims to study the effect of gold ore grinding on the wear rate of grinding balls. Methods. Six boulder rock samples were selected from some KSA mines; five core samples were taken from each of them to identify the mechanical properties (compressive strength, Young’s modulus, and Poisson’s ratio). These mechanical properties were applied to identify the hardness class of all 30 core samples. Five samples with different mechanical properties from the same boulder sample were milled to study the effect of the compressive strength difference and grinding time on wear rate. Then, six samples were taken from different regions with similar mechanical properties but different petrographic characteristics. They were also milled under the same grinding conditions to study the effect of the microscopic mineral composition on the wear rate. Findings. The results showed that the wear rate increased with the improving mechanical properties and with the increa-sing grinding time. On the other hand, the results based on different microscopic descriptions of the six samples showed that despite similar mechanical properties, the wear rates differed. Petrographic characteristics confirmed the presence of quartz in most of the samples as an associated mineral; it is likely that it has the greatest effect on the grinding ball wear. Originality. The paper proposes a method for investigating ore heterogeneity, which has a major impact on the wear rate during a grinding process, as well as on the reducing costs and improving efficiency of grinding media. Practical implications. The research emphasizes the importance of investigating variables (e.g. ore heterogeneity) other than ball size, grinding medium composition, and wet or dry grinding that have a substantial impact on grinding efficiency. The findings could be applied in feasibility studies to calculate and evaluate grinding costs versus grinding efficiency.