Improved models for predicting heap leaching hydrodynamics

Ilankoon, I.M.S.K., Neethling, S.J., Hydroprocess 2014, 2014

Heap leaching is one of the most important hydrometallurgical techniques for the extraction of valuable metals from low grade ores, despite the low recoveries when compared to conventional mineral extraction methods such as froth flotation followed by smelting. There are a number of reasons for the lower recoveries including both chemical and hydrodynamic effects. This paper will cover the development of improved models for predicting the hydrodynamics of the complex unsaturated flow within heap leaching systems.

The authors have shown that the liquid held within the particles has a very different behaviour to that between the particles and thus, in order to successfully model these systems the effect of inter- and intra-particle porosity on heap flow behaviour needs to be separated. The model form was developed theoretically and verified using column leaching liquid flow experiments. This model was initially validated for non-porous spherical particles and narrowly sizes copper ore particles of about 5% porosity.

In this paper the inter-particle flow model is validated for complex particle size distributions that are representative of those found industrially. In addition, liquid flow experiments were performed in a pseudo 2-D packed bed to investigate the horizontal liquid distribution from, for instance, dripper points. The aim of this is to assess the relative importance of capillarity compared to other dispersive effects in both the inter and intra-particle spaces.

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