Mechanism of catalytic action of cupric ions in ferric salts leaching of millerite
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Wrocław University of Technology
Częstochowa Academy of Pedagogy
Publication date: 2001-01-01
Physicochem. Probl. Miner. Process. 2001;35(1):67–72
Based on experimental leaching results of millerite as well as changes in the composition and microstructure of solid residue surface after leaching with ferric salts acid solutions the mechanism of catalytic action of cupric ions has been proposed. The solid residues were examined using a scanning microscope (SEM), X-ray diffraction, electron microprobe and chemical analyses. It was found that cupric ions added to the ferric chloride solution oxidizes catalitically the sulphide ions on the surface of millerite to the elemental sulphur. During the ferric sulphate leaching of millerite a sulphurrich sulphide layer passivating the surface of the mineral was found, and addition of cupric ions has no influence on the leaching rate.