1. Introduction
Ball mill is widely used in mineral industries as size reduction equipment in which ore is broken into wide range of particle sizes. For economic recovery of the valuable minerals, ball mill grinding circuits must provide stable particle size distributions. Control of product particle size has aroused a lot of interest in the mineral engineering communities [1]–[5]. As many other industrial processes, grinding circuit should also operate in a way to maximize the mill efficiency, that is, to increase the fresh ore feed rate as much as possible [6], [7].