Mineral liberation analysis on coal components separated using typical comminution methods

Abstract To study the characteristics of different comminution methods during the separation of coal components, mineral liberation analysis (MLA) was performed on typical coal variants produced in Western China. In this work, the granularity, free surface, phase specific surface area, and mineral phase interfaces of coal and its primary mineral constituents under the actions of rod milling and ball milling were investigated. For the same milling time, ball milling was found to be more effective in reducing grain sizes and producing more concentrated grain size distributions. The mineral components with different dissemination grain sizes and dissemination patterns exhibited different separation grades and responded differently to each comminution method. The recovery rates of coal and siderite monomers for rod milling were 92.85% and 61.56%, respectively. The recovery rates of pyrite and quartz monomers for ball milling were 80.52% and 52.60%, respectively. The free surface and phase specific surface areas were compressively analyzed for optimum mineral separation, and separation models were developed for typical coal components under the actions of each comminution method. The compaction forces associated with rod milling tended to induce intergranular cracks, whereas the impact forces associated with ball milling generated intragranular cracks; the latter is beneficial for separating minerals with relatively fine disseminated grain sizes.