Normalized Redox Potential Used to Assess Chalcopyrite Column Leaching

Okamoto, Hideyuki; Nakayama, Ryoichi; Kuroiwa, Shigeto; Hiroyoshi, Naoki; Tsunekawa, Masami

doi:10.2473/shigentosozai.121.246

Cited by 11 publications

(5 citation statements)

References 5 publications

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“…From previous chemical leaching studies, experimental conditions such as metal ion concentrations, solid/liquid ratios and co-existing minerals were shown to affect the optimal Eh value for Cu extraction (Okamoto 2004(Okamoto , 2005Hiroyoshi 2008aHiroyoshi , 2008b. This could cause misleading interpretation of results obtained from different studies conducted under different conditions.…”

Section: Fe-oxidizersmentioning

confidence: 99%

“…This could cause misleading interpretation of results obtained from different studies conducted under different conditions. In order to define the optimal Eh value independent of such conditional differences, "the normalized redox potential (Enormal)" was proposed for a reaction model assuming the formation of intermediate Cu2S from chalcopyrite, with its optimal range being 0 ≤ Enormal ≤ 1 (highest copper extraction rate achieved at Enormal ≈ 0.43; Okamoto et al 2004Okamoto et al , 2005Hiroyoshi et al 2008aHiroyoshi et al , 2008b:…”

Section: Fe-oxidizersmentioning

confidence: 99%

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Microbiological Redox Potential Control to Improve the Efficiency of Chalcopyrite Bioleaching

Masaki

Hirajima

Sasaki

et al. 2018

Geomicrobiology Journal

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The effect of controlling the redox potential (Eh) on chalcopyrite bioleaching kinetics was studied as a new aspect of redox control during chalcopyrite bioleaching, and its mechanism was investigated by employing the "normalized" solution redox potential (Enormal) and the reaction kinetics model. Different Eh ranges were established by use of different acidophiles (Sulfobacillus acidophilus YTF1; Sulfobacillus sibiricus N1; Acidimicrobium ferrooxidans ICP; Acidiplasma sp. Fv-AP). Cu dissolution was very susceptible to real-time change in Eh during the reaction. It was found that efficiency of bioleaching of chalcopyrite can be effectively evaluated on the basis of Enormal, since it is normalized for real-time fluctuations of concentrations of major metal solutes during bioleaching. For steady Cu solubilization during bioleaching at a maximum rate, it was important to maintain a redox potential range of 0 ≤ Enormal ≤ 1 (-0.35 mV optimal) at the mineral surface by employing a "weak" ion-oxidizer. This led to a copper recovery of > 75%. At higher Enormal levels (Enormal > 1 by "strong" microbial Fe 2+ oxidation), Cu solubilization was slowed by diffusion through the product film at the mineral surface (< 50% Cu recovery) caused by low reactivity of the chalcopyrite and by secondary passivation of the chalcopyrite surface, mainly by jarosite.

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Section: Fe-oxidizersmentioning

confidence: 99%

Section: Fe-oxidizersmentioning

confidence: 99%

Microbiological Redox Potential Control to Improve the Efficiency of Chalcopyrite Bioleaching

Masaki

Hirajima

Sasaki

et al. 2018

Geomicrobiology Journal

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“…Here, experimental conditions (i.e., metal ion concentrations, solid/liquid ratios and co-existing minerals) can affect the optimal E h value for Cu solubilization, causing misleading interpretation of data produced under different conditions [10,11,13,14]. To define the optimal E h regardless of such conditional differences, the "normalized redox potential (E normal )" was proposed, with its optimal range being 0 ≤ E normal ≤ 1 (greatest Cu solubilization rate achieved at E normal ≈ 0.43 at 30 • C [10,11,13,14]:…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, in such situations where chalcopyrite and enargite co-exist in the concentrate, the interpretation of AC's catalytic function can become complicated. So far, the E normal theory has been proposed only for the chalcopyrite leaching behavior [10,11,13,14] but not for enargite.…”

Section: Introductionmentioning

confidence: 99%

Carbon-Assisted Bioleaching of Chalcopyrite and Three Chalcopyrite/Enargite-Bearing Complex Concentrates

et al. 2021

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Overcoming the slow-leaching kinetics of refractory primary copper sulfides is crucial to secure future copper sources. Here, the effect of carbon was investigated as a catalyst for a bioleaching reaction. First, the mechanism of carbon-assisted bioleaching was elucidated using the model chalcopyrite mineral, under specified low-redox potentials, by considering the concept of Enormal. The carbon catalyst effectively controlled the Eh level in bioleaching liquors, which would otherwise exceed its optimal range (0 ≤ Enormal ≤ 1) due to active regeneration of Fe3+ by microbes. Additionally, Enormal of ~0.3 was shown to maximize the carbon-assisted bioleaching of the model chalcopyrite mineral. Secondly, carbon-assisted bioleaching was tested for three types of chalcopyrite/enargite-bearing complex concentrates. A trend was found that the optimal Eh level for a maximum Cu solubilization increases in response to the decreasing chalcopyrite/enargite ratio in the concentrate: When chalcopyrite dominates over enargite, the optimal Eh was found to satisfy 0 ≤ Enormal ≤ 1. As enargite becomes more abundant than chalcopyrite, the optimal Eh for the greatest Cu dissolution was shifted to higher values. Overall, modifying the Eh level by adjusting AC doses to maximize Cu solubilization from the concentrate of complex mineralogy was shown to be useful.

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“…Another phenomenon is that there is an optimum redox potential for the leaching of chalcopyrite, i.e., the leaching rate increases with increasing the redox potential and then reaches a maximum rate at an optimum redox potential, after which it decreases with the increasing of potentials, and the rate becomes less dependent on the potential at very high potentials [6,10,[22][23][24]. Besides the above two phenomena, iron is preferentially dissolved into solutions compared to copper during the initial period of chalcopyrite leaching and a copper-rich layer is formed on the surface of the chalcopyrite particles [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

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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Normalized Redox Potential Used to Assess Chalcopyrite Column Leaching

Cited by 11 publications

References 5 publications

Microbiological Redox Potential Control to Improve the Efficiency of Chalcopyrite Bioleaching

Microbiological Redox Potential Control to Improve the Efficiency of Chalcopyrite Bioleaching

Carbon-Assisted Bioleaching of Chalcopyrite and Three Chalcopyrite/Enargite-Bearing Complex Concentrates

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

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