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The bacteria column leaching experiment of low grade sulphide ore was conducted and the ore granular
media were scanned by X-ray computerised tomography scanner before and after leaching. Based on the
image processing operation, the spatial distribution of the porosity, and the change of pore size distribution
and connectivity before and after leaching were investigated. In addition, the mechanism of pore evolution
during leaching was also analysed. The results indicate that the porosity, pore size and pore connectivity of
the ore granular media during leaching all have spatial and temporal variability. After leaching, the porosity
distribution along the column became more inhomogeneous and assumes a decreasing trend from top to
bottom, especially the bottom zone, with porosity decreasing greatly. The amount of larger pores increased
at the top and middle zones after leaching while decreased at bottom zone. The connectivity of the top and
middle zone was improved but deteriorated at the bottom zone. The main mechanisms for pore evolution are
the subsidence of the entire granular ore body and the transportation and accumulation of the fine particles,
chemical precipitates and colloidal substance at local areas.
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