Power-based comminution calculations using Ausgrind

Ausgrind is Ausenco’s in-house program used for power-based comminution calculations. Proprietary calculations have been developed and reconciled with unit process operation and benchmarked with plant performance.

Ore breakage data from characterization and variability testwork, equipment geometry, flowsheet configuration, efficiency factors and operating conditions are inputs. Ausgrind contains a database of operating data and circuit types from many operations and over a wide range of ore types and throughputs. These are referenced when developing flowsheets and circuit efficiency factors which correct the specific energy required to grind from the nominated feed size to the specified product size. As circuit efficiency factors are determined in Ausgrind, correction factors such as those listed by Bond and Rowland are not employed.

The principal outputs are the total circuit specific energy and the specific energy for each of the components in the comminution circuit. Ausgrind provides a valuable tool for evaluating comminution options and optimizing circuit and equipment configurations.

Comminution is a pivotal and critical component in most mineral processing operations for several reasons: it liberates the valuable mineral rendering it amenable to subsequent processes; it represents one of the highest capital cost investments for unit processes in the treatment plant; and it contributes a significant component to operating cost due to its high energy requirements. Therefore, determining the most cost-effective circuit and predicting the energy requirement for each unit process to achieve the desired size reduction in the product stream from the comminution circuit are critical tasks for circuit design.

This paper describes the Ausgrind approach for estimating power and design of comminution circuits and compares its outcomes to other published ap- proaches. Practical examples are also presented, showing applications for different circuit configurations.