The influence of particle size on energy consumption and water recovery in comminution and dewatering systems

Particle size is a key design variable in minerals beneficiation. Given declining grades in mineral ore reserves, finer grinding is being used to increase mineral liberation, leading to increased milling energy input. The particle size from the mill also has an effect on water recovery in downstream dewatering systems. This paper presents models for water recovery from the downstream thickening, filtration and tailings permeation and decantation processes, using Sauter Mean Diameter to characterise average particle size. On the basis of these models, a relationship between mill energy consumption and water recovery is established. To test the effect of particle size on these processes, data drawn from an industrial case study is used. The results confirm that as mill energy is increased, the particle size is decreased resulting in lower water recovery from the dewatering systems. This makes it possible to explore the trade-off between energy, liberation and water recovery.