Mechanism of anodic dissolution of chalcocite in hydrochloric acid solution

Rate laws for the anodic dissolution of Butte chalcocite in dilute copper(II) chloride solution

“…We again assume that Cu is univalent in Cu2S, CuS, the related nonstoichiometric compounds, and the various intermediate surface species that are invoked in the three mechanisms. Experimental evidence supporting this assumption was cited previously (Parikh and Liddell, 1990). For Cu2S undergoing anodic dissolution, there are a large number of processes that might be considered potentially rate determining: adsorption or desorption from the electrode surface, transport between the bulk solution or solid phases and the electrode surface, and chemical or electrochemical reactions occurring at the solid-electrolyte interface.…”

“…On the basis of the rate laws given above, it is now possible to propose detailed mechanisms which can account for both the empirical reaction orders and the various products observed at different disk potentials. In both this and the previous work (Parikh and Liddell, 1990), the overall reactions and mechanisms at high and low potentials are limiting cases of those developed for the intermediate regime. However, the mechanisms presented here for high and low potentials were developed independently of the one for intermediate potentials.…”

“…The literature on the dissolution reactions of chalcocite and other binary copper sulfides in chloride media has been described by Parikh (1988) and Srinivasan (1990). Chalcocite preferentially loses copper during anodic dissolution (Parikh, 1988; Parikh and Liddell, 1990; Srinivasan, 1990) and oxidative leaching (King et al, 1975), forming a series of progressively more copper-deficient nonstoichiometric sulfides. The sequence of nonstoichiometric intermediates formed by anodic dissolution terminates with CuS, which produces no solids other than elemental sulfur (Parikh, 1988; Srinivasan, 1990); King et al (1975) reported the possible formation of a further intermediate, Cuo,79oS, but this apparently has not been confirmed by other studies.…”

“…For chloride-containing electrolytes, data obtained by MacKinnon (1976) suggest that the rate of anodic dissolution of chalcocite increases in a nonlinear fashion with increasing chloride concentration; the effect of ligand concentration was not thoroughly studied. Parikh and Liddell (1990) have recently reported a mechanism for the anodic dissolution of Transvaal Cu2S in HC1 solution. Three different potential regimes giving qualitatively different products were identified using a rotating ring disk electrode with a demountable Cu2S disk, and the mechanism successfully accounts for the products observed in each case.…”

Aqueous processing of minerals and materials

“…Liddell used the partial equilibrium model to describe the HCI leaching of ilmenite-hematite mixtures. 72 Goodenough and colleagues described a bipolar packed bed electrode in which covellite is decomposed by simultaneous oxidation and reduction. 32 EI-Raghy and EI-Dermerdash calculated Eh-pH diagrams for Mo-S-Hp, Zn-S-H 0, and Pb-S-H 2 0 systems at elevateJtemperatures, using their activity-term method.…”