Evolvement of permeability of ore granular media during heap leaching based on image analysis

The column leaching experiment of ore granular media was carried out with the home-made multi-functional experimental apparatus and the pore structure of ore granular media was scanned by the X-ray computed tomography machine before and after leaching. The porosities of each section before and after leaching were calculated based on CT images processing, and the permeability of each zone before and after leaching were also calculated with Carman-Kozeny equation. The permeability evolvement law was disclosed. The results indicate that before leaching the permeability of the ore granular media in different height has not much difference and the value ranges from 5.70× 10^-4mm^2 to 1.11 × 10^-3 mm^2, where the lowest one locates in the bottom zone. After leaching the permeability distributes inhomogeneously along the height of the column and the value ranges from 3.44 × 10^4 mm^2 to 2.25 × 10^-2 mm^2, where the lowest one is in the same place. Except for the bottom zone, the permeability of other zones increases after leaching, especially the top zone. Through comparison of the permeability at bottom zone before and after leaching, the whole permeability after leaching decreases by 39.65% that coincides with the measured experimental data.