The electrochemical oxidation of chalcopyrite in ammoniacal solutions

Study of the dissolution of chalcopyrite in solutions of different ammonium salts

“…The Fe:S ratio is 1.9:1, which represents a significant shift from the 1:2 ratio of pure chalcopyrite. The presence of sulphur on the surface was previously reported by Warren and Wadsworth (1984), who upon scraping off and dissolving the surface film from their experiments identified some orthorhombic sulphur, confirming that elemental sulphur was present in both the surface film and leachate. The researchers attributed this to the disproportionation of some of the intermediate sulphur species expected to be found in the leachate.…”

“…Fe 2 O 3 or its hydrated form Fe 2 O 3 .xH 2 O (Beckstead and Miller, 1977b;Yin et al, 1995;Forward and Mackiw, 1955;Feng and Van Deventer, 2002) and Fe(OH) 3 (Yin et al, 1995;Warren and Wadsworth, 1984) have been reported to be the surface products of chalcopyrite oxidation. Warren and Wadsworth (1984) studied the electrochemical oxidation of chalcopyrite in ammonia-ammonium sulphate solutions and reported significant amounts of ferrous iron (3-20%) in the product film. The authors postulated that a ferrous iron intermediate was formed, which can be readily oxidized to ferric, and the oxidation can be achieved even if only traces of dissolved oxygen are present.…”

The leaching kinetics of chalcopyrite (CuFeS2) in ammonium lodide solutions with iodine

“…The results showed that the reaction product was mostly amorphous, which is consistent with the results of Warren and Wadsworth. [14] Figure 11 shows a scanning electron micrograph (SEM) of the reaction product, amorphous ferric iron hydroxide, after seven successive leachings. The amorphous ferric iron hydroxide on the surface was porous and friable, as evidenced by its easy separation from the underlying chalcopyrite by gentle scraping.…”

“…Warren and Wadsworth [14] studied the anodic dissolution of chalcopyrite in ammoniacal solutions. They found that at low overpotentials a deficient layer of Cu 1Ϫx FeS 2 was formed.…”

Sustainable phycocyanin production from Arthrospira platensis using solar-control thin film coated photobioreactor

“…The oxidative dissolution reaction (1), suggests that the oxidant in this reaction is oxygen as was generally accepted by previous researchers over the years (Forward and Mackiw, 1955;Kuhn, Arbiter and Kling, 1974;Beckstead and Miller, 1977b;Reilly and Scott, 1977;Warren and Wadsworth, 1984;Duyvesteyn and Sabacky, 1993;Arbiter and McNulty, 1999) . However, earlier work by the authors (Moyo et al, 2015) showed that copper(II) is the primary oxidant in the system, itself being reduced to copper(I), which would in turn be oxidised back to copper(II) in solution by oxygen.…”