Evaluation of Shell and Pulp Lifters in Semiautogenous Mills with the Dem Simulation

Abstract

Today's high capacity semiautogenous grinding (SAG) mills expend vast amounts of energy and in doing so consume tons of steel balls and shell liners. The energy efficiency of these mills can be directly examined by looking at the motion of rocks and grinding balls inside the mill. The make-up of the charge and the design of lifter bars atta-ched to the inside of the mill shell can be chosen parti-cularly to maximize the mass of ore fractured per unit of energy spent. At the same time, the unnecessary collisions of balls against the mill shell can be prevented. Further more, the cascading charge flow can be altered in a way to maximize grinding efficiency. The harsh environment in the mill prevents any instrumentation in the interior of the mill. Instead, the simulation of charge motion became a practical tool with the emergence of the discrete element method (DEM).