Exploring the fundamentals of impact breakage events in grinding

Grinding in mineral processing is used to liberate valuable minerals from ore and prepare feed for mineral separation. It accounts for up to 50% of a concentrator's energy consumption. Ball mills are usually adopted in grinding processes; however their energy efficiency is low. Consequently, a small improvement can lead to important savings.Population balance models can be used for ball mill optimization, but their use is limited because they are black box models based on incomplete information about the breakage events inside ball mills. Charge motion simulators, based on the discrete element method (DEM), not only provide information about charge media motion, but also collision energy distributions inside ball mills. Ball mill optimization can be achieved using charge motion simulators if the product size distribution can be predicted by linking charge motion results with single particle breakage tests.Single particle drop tests were carried out to determine the effect of different levels of impact energy. Fundamental ore breakage model equations for an impact breakage event were established, and were applied for the drop weight tests based on a theoretical breakage mechanism. The energy consumptions are calculated with the given feed and product size distribution with the established equations. The comparison of two kinds of drop weight test devices were made and the effect of impact speeds of drop blocks on particle breakage at constant impact energy level was also discussed