Population balance model for crushed ore agglomeration for heap leach operations

Abstract

Agglomerate size distribution is a pretreatment step in low grade heap leach operations. The present work focuses on modeling the evolution of size distribution in batch agglomeration drum. Up to now there has been no successful work on modeling of crushed ore agglomeration although the framework for population balance modeling of pelletization and granulation is readily available. Different batch agglomeration drums were used to study the agglomeration kinetics of copper, gold and nickel ores. The agglomerate size distribution is inherently subject to random fluctuation due to the very nature of the process. Yet, with careful experimentation and size analysis the evolution of size distribution can be followed. The population balance model employing the random coalescence model with a constant rate kernel is shown to work well in a lab scale agglomerator experiments. It was observed that in a small drum agglomerates begin to break in a short time whereas the growth is uniform in the larger drum. The experimental agglomerate size distributions exhibit self-preserving size spectra which confirms the applicability of coalescence rate based model. The present work lays out the fundamentals for applying the population balance concept to batch agglomeration, specifically crushed ore agglomeration. The experimental difficulties and how to overcome them are described. ©2014 Hosokawa Powder Technology Foundation.