The effects of electrical comminution on the mineral liberation and surface chemistry of a porphyry copper ore

摘要

The surface chemistry and mineral liberation changes of a porphyry copper ore after SelFrag electrical comminution have been investigated using X-ray photoelectron spectroscopy (XPS) and mineral liberation analysis (MLA). Previous studies suggest that electrical comminution has the potential to improve the downstream flotation recoveries, due to increased mineral liberation. However, until now the effects on the surface chemistry have not been investigated in detail.The mineral liberation results showed that chalcopyrite was more liberated in the electrical comminution product than in the mechanical comminution, noticeably in the coarser size fractions. The surface chemistry of pure chalcopyrite was investigated, using XPS, and high resolution scans of iron and sulphur showed that both comminution methods led to iron oxidising preferentially leaving behind a passivating film of copper sulphides. However, the SelFrag oxidisation was a lot more severe with more iron oxide being produced and further oxidation of the remaining copper sulphides into copper sulphate. Flotation tests showed that SelFrag treatment improved the overall cumulative flotation recovery by 4%, this was attributed to the rod mill removing the passivating layers on the more liberated chalcopyrite.