Passive and transpassive anodic behavior of chalcopyrite in acid solutions

Warren, G. W.; Wadsworth, M.E.; El‐Raghy, S. M.

doi:10.1007/bf02650014

Cited by 109 publications

(69 citation statements)

References 15 publications

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“…That is, chalcopyrite can be transformed to Cu 5 FeS 4 through the non-oxidative dissolution mechanism, then according to the diffusion rates of Cu 2+ and H 2 S, the released H 2 S may react with Cu 2+ to form CuS either in solution or at the diffusion channel in the Cu 5 FeS 4 intermediate phase, as shown in Figure 4. This assumption is in accordance with the report of Warren [30], in which two intermediate products formed during the anodic dissolution of chalcopyrite. In the low potential region these intermediates form passive layers, and the rate of transport is well correlated by the SatoCohen passivation model.…”

Section: Balanced Concentrations Of Cu 2+ and H2s In Aqueous Solutionsupporting

confidence: 80%

“…Among the other three possible routes, CuS seems to be the most likely intermediate, Cu 5 FeS 4 is the second most likely, and Cu 2 S is the least likely intermediate according to its relatively high potential. However, Warren proposed two intermediate sulfide phases which appeared to be formed based on the current and mass balance measurements [30]. Majuste detected the existence of bornite as an intermediate during an electrochemical dissolution experiment of chalcopyrite by synchrotron small-angle X-ray diffraction [31].…”

Section: +mentioning

confidence: 99%

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Thermodynamic Analysis of Possible Chalcopyrite Dissolution Mechanism in Sulfuric Acidic Aqueous Solution

Wang

Chang

et al. 2016

Metals

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Abstract:The dissolution routes of chalcopyrite in acidic sulfate aqueous solution have been discussed by thermodynamic calculation under different aqueous species concentrations, such as Cu 2+ , Fe 2+ and H 2 S. The results show that for both oxidative dissolution and non-oxidative dissolution of chalcopyrite, the dissolution process undergoes several intermediate steps before completely decomposing to Cu 2+ , Fe 2+ and elemental sulfur, in which bornite and covellite are the most likely intermediates. The dissolution routes of the secondary intermediates have also been discussed and covellite is the most likely final intermediate. Based on these results, some frequently reported phenomena, such as the existence of an optima redox potential range, the promotive action of the addition of Cu 2+ and Fe 2+ , as well as the preferential release of Fe 2+ in the chalcopyrite leaching process, have been explained and elucidated.

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Section: Balanced Concentrations Of Cu 2+ and H2s In Aqueous Solutionsupporting

confidence: 80%

Section: +mentioning

confidence: 99%

Thermodynamic Analysis of Possible Chalcopyrite Dissolution Mechanism in Sulfuric Acidic Aqueous Solution

Wang

Chang

et al. 2016

Metals

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“…It has been variously described as a metal-de®cient, chalcopyrite-like sul®de (Biegler and Home, 1985;Warren et al, 1982), a nonporous elemental sulfur layer (Dutrizac, 1989;Hirato et al, 1987), or a polysul®de (CuS x , where x > 2) (Majima et al, 1988;Parker et al, 1981).Whatever the nature of this layer, it has been observed consistently in this study that higher redox potentials and increased ferric ion concentrations promote rapid passivation of the chalcopyrite surface. The most likely explanation is that formation of the passivating layer is delayed at low redox potential, facilitating the continued dissolution of the mineral (Figs.…”

Section: Ferric Ion As a Promoter Of Rapid Passivation Of Chalcopyritementioning

confidence: 50%

Control of the redox potential by oxygen limitation improves bacterial leaching of chalcopyrite

Third

Cord‐Ruwisch

Watling

2002

Biotech & Bioengineering

131

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Shake flask and stirred tank bioleaching experiments showed that the dissolution of chalcopyrite is inhibited by ferric ion concentrations as low as 200 mg L(-1) and redox potentials >420 mV (vs. Ag/AgCl). Chemical leaching of chalcopyrite (4% suspension, surface area 2.3 m2 g(-1)) was enhanced fourfold in the presence of 0.1 M ferrous sulphate compared with 0.1 M ferric sulphate. A computer-controlled reactor was designed to function as a "potentiostat"-bioreactor by arresting the air supply to the reactor when the redox potential in solution was greater than a designated setpoint. Leaching at a low, constant redox potential (380 mV vs. Ag/AgCl) achieved final copper recoveries of 52%-61%, which was twice that achieved with a continuous supply of oxygen (<30% extraction). The bacterial populations were observed to continue growing under oxygen limitation but in a controlled manner that was found to improve chalcopyrite dissolution. As the control mechanism is easily established and is likely to decrease production cost, the use of this technology may find application in industry.

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“…Numerous studies of pyrite oxidation under a wide range of conditions have been undertaken, and there has been a significant number of studies of the oxidation of chalcopyrite. In particular, the electrochemical oxidation and reduction of the chalcopyrite surface has been studied by Gardner and Woods (1979), Parker et al (1981a, b); Warren et al (1982); McMillan et al (1982); Kelsall and Page (1984); Biegler and Home (1985); Cattarin et al (1990);and Yin et al (1995). Amongst the many studies of electrochemical and aqueous oxidation of pyrite are Biegler and Swift (1979), McKibben and Barnes (1986), Moses et al (1987), Mishra and Osseo-Asare (1992), Moses and Herman (1991), Tao et al (1994), Williamson and Rimstidt (1994) and Kelsall et al (1996).…”

Section: Introductionmentioning

confidence: 99%

Surface oxidation studies of chalcopyrite and pyrite by glancing-angle X-ray absorption spectroscopy (REFLEXAFS)

et al. 1999

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The oxidation of chalcopyrite and pyrite was examined using Fe-K-and Cu-K-edge REFLEXAFS spectroscopy. The Fe XANES of the pyrite proved to be a very sensitive indicator of oxidation, revealing the development of a goethiteqike surface species; the EXAFS data showed an increasing O:S ratio with the degree of oxidation and gave Fe-O distances of c. 1.9 A. On the oxidized chalcopyrite surfaces, the development of Fe-O and Cu-O species was observed, with both the XANES and EXAFS revealing the progressive development of these species with oxidation. Differences in the sensitivity of the XANES and EXAFS to the degree of oxidation can be related to the degree of long range order and changes in the intensity of the pre-edge feature of the Fe are a function of its oxidation state and coordination geometry in the surface species.

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Passive and transpassive anodic behavior of chalcopyrite in acid solutions

Cited by 109 publications

References 15 publications

Thermodynamic Analysis of Possible Chalcopyrite Dissolution Mechanism in Sulfuric Acidic Aqueous Solution

Thermodynamic Analysis of Possible Chalcopyrite Dissolution Mechanism in Sulfuric Acidic Aqueous Solution

Control of the redox potential by oxygen limitation improves bacterial leaching of chalcopyrite

Surface oxidation studies of chalcopyrite and pyrite by glancing-angle X-ray absorption spectroscopy (REFLEXAFS)

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