Bioleaching of chalcopyrite by pure and mixed cultures of Acidithiobacillus spp. and Leptospirillum ferriphilum

Abstract:To better understand chalcopyrite leach mechanisms and kinetics, for improved Cu extraction during hydrometallurgical processing, chalcopyrite leaching has been conducted at solution redox potential 750 mV, 35-75˝C, and pH 1.0 with and without aqueous iron addition, and pH 1.5 and 2.0 without aqueous iron addition. The activation energy (E a ) values derived indicate chalcopyrite dissolution is initially surface chemical reaction controlled, which is associated with the activities of Fe 3+ and H + with reaction orders of 0.12 and´0.28, respectively. A surface diffusion controlled mechanism is proposed for the later leaching stage with correspondingly low E a values. Surface analyses indicate surface products (predominantly S n 2´a nd S 0 ) did not inhibit chalcopyrite dissolution, consistent with the increased surface area normalised leach rate during the later stage. The addition of aqueous iron plays an important role in accelerating Cu leaching rates, especially at lower temperature, primarily by reducing the length of time of the initial surface chemical reaction controlled stage.

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“…Many investigators [4,[84][85][86] have pointed out that Equation (10) is also relevant to both acid mine drainage and heap leaching:…”

Section: Identification Of Reactions and Mechanismsmentioning

confidence: 99%

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Wei

Qian

et al. 2016

Minerals

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“…It has been reported that strains of Acidithiobacillus caldus were isolated from several copper mines in China, all of which belong to moderately thermophilic bacteria and can oxidize elemental sulfur and thiosulfate [26]. It has been reported that mixing A. caldus with Leptospirillum ferriphilum to leach chalcopyrite achieved a high leaching rate [7]. Additionally, the extraction of copper reached 90 % in 3 months using Sulfobacillus acidophilus and Sulfobacillus yellowstonensis enrichment [12].…”

Section: Introductionmentioning

confidence: 99%

Expression of Critical Sulfur- and Iron-Oxidation Genes and the Community Dynamics During Bioleaching of Chalcopyrite Concentrate by Moderate Thermophiles

et al. 2015

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Sulfate adenylyltransferase gene and 4Fe-4S ferredoxin gene are the key genes related to sulfur and iron oxidations during bioleaching system, respectively. In order to better understand the bioleaching and microorganism synergistic mechanism in chalcopyrite bioleaching by mixed culture of moderate thermophiles, expressions of the two energy metabolism genes and community dynamics of free and attached microorganisms were investigated. Specific primers were designed for real-time quantitative PCR to study the expression of these genes. Real-time PCR results showed that sulfate adenylyltransferase gene was more highly expressed in Sulfobacillus thermosulfidooxidans than that in Acidithiobacillus caldus, and expression of 4Fe-4S ferredoxin gene was higher in Ferroplasma thermophilum than that in S. thermosulfidooxidans and Leptospirillum ferriphilum. The results indicated that in the bioleaching system of chalcopyrite concentrate, sulfur and iron oxidations were mainly performed by S. thermosulfidooxidans and F. thermophilum, respectively. The community dynamics results revealed that S. thermosulfidooxidans took up the largest proportion during the whole period, followed by F. thermophilum, A. caldus, and L. ferriphilum. The CCA analysis showed that 4Fe-4S ferredoxin gene expression was mainly affected (positively correlated) by high pH and elevated concentration of ferrous ion, while no factor was observed to prominently influence the expression of sulfate adenylyltransferase gene.

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“…Secondly, the low pH helps to maintain sufficient Fe 2+ in the solution as an energy source for the iron-oxidizing microorganisms. Moreover, the low pH can inhibit the formation of a passivation layer on the surface of ore particles (Fu et al, 2008). However, addition of acid will also result in higher cost, especially in commercially operating bioheaps.…”

Section: Bioleaching Testsmentioning

confidence: 99%

Column bioleaching of low-grade copper ore by Acidithiobacillus ferrooxidans in pure and mixed cultures with a heterotrophic acidophile Acidiphilium sp.

Yang

Diao

et al. 2013

Hydrometallurgy

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Bioleaching of chalcopyrite by pure and mixed cultures of Acidithiobacillus spp. and Leptospirillum ferriphilum

Cited by 90 publications

References 18 publications

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Kinetics and Mechanisms of Chalcopyrite Dissolution at Controlled Redox Potential of 750 mV in Sulfuric Acid Solution

Expression of Critical Sulfur- and Iron-Oxidation Genes and the Community Dynamics During Bioleaching of Chalcopyrite Concentrate by Moderate Thermophiles

Column bioleaching of low-grade copper ore by Acidithiobacillus ferrooxidans in pure and mixed cultures with a heterotrophic acidophile Acidiphilium sp.

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