Selection of Comminution Circuits for Improved Efficiency

This paper examines the design of comminution circuits and the issues that impact on comminution circuit efficiency.Circuit efficiency is discussed, principally from the perspective of power efficiency. However, operating efficiency, maintenance efficiency, capital expenditure and return on investment are often the key efficiency factors in project development outweighing power efficiency considerations. Comminution circuits have progressed from circuits comprising simple crushing machines, for example stamp batteries, through multi-stage crushing and staged grinding, to single stage crushing and semi-autogenous grinding (SAG) and ball mill(SAB) circuits. This progression has, not necessarily, been accompanied by an improvement in the efficiency of power utilisation in achieving the target grind size,but has seen an improvement in the overall efficiency of mineral processing as measured by the overall cost of grinding to the required size for effective downstream beneficiation of the value metal or mineral. In the future, projects that add value by improving power efficiency and reducing CO2-equivalent output may earn Emission Reduction Units (ERU's). The value of an ERU is hard to predict and the achievable reduction will be a function of comminution technology and site specific factors such as the method of power production.