Effects of grain boundary fracturing on grade variation of comminuted slag

Abstract

Prediction of the mineral liberation resulting from comminution is an important challenge for every mineral engineer. Many liberation models have been proposed, but few have focused on the abnormal distribution of comminuted products. The influence of grain boundary fracturing on the grade variation of comminuted slag has now been subjected to detailed investigation. A grade model based on the exposure model was derived, which provides simple mathematical relationships between grade variations, particlesize distribution, grain-size distribution, the intergranular fracturing factor and the content of valuable components. A jaw crusher with closed sets of 8, 10, 15 and 18 mm (denoted C8, C10, etc.) was used to comminute slag samples individually and the products were screened carefully prior to measurement. The various closed sets produced different particle-size distributions as well as dissimilar grade variations. The degree of grade variation of C8 was 134% and that of C18 151%. Wider closed sets produced coarser particle-size distributions and less grade variations. The amount of intergranular fracturing was the major factor that influenced the degree of grade variation.