Authors: E. Zhou, Jian Kang Wen, Ren Man Ruan, Dian Zuo Wang
Abstract: Based on the bioleaching mechanism and electrochemical studies of covellite, the
dissolution rate of covellite mineral is accelerated through increasing the redox potential (Eh) of the
leach. In the present work, some methods were adopted to enhance the bioleaching of covellite
concentrate (collected from Zijinshan copper mine, Fujian province, China) by adding different
oxidants such as pure pyrite, ferric ions and H2O2. The goal of this study was to provide appropriate
operating parameters for the industry application and increase the efficiency of the bioleaching of
copper mine. The results showed that the optimal way to increase the redox potential (Eh) level was
the addition of pure pyrite. This method could effectively raise the Eh of bioleaching process while
the effect of environmental change was negligible. It could quicken the leaching process and
enhance the final copper recovery through the addition of pyrite by 1:1 or 1:2 ratio of covellite
concentrate to pyrite.
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Authors: F. Beolchini, A. Dell’Anno, L. Rocchetti, Francesco Vegliò, R. Danovaro
Abstract: This paper deals with biohydrometallurgy applied for the remediation of sediments contaminated by heavy metals. Both metal mobilization by bioleaching and metal stabilization by sulfate reducing bacteria stimulation have been investigated. In the first case, leaching experiments were performed with different microbial strains: i) autotrophic Fe/S-oxidizing bacteria, ii) heterotrophic Fe reducing bacteria, and iii) a mix of them. The highest extraction yields were 90% for Cu, Cd, Hg and Zn and were achieved with a consortium of the autotrophic and the heterotrophic strains. In the second case, anaerobic microcosm experiments were performed according to a full factorial experiment where the main factors were: i) acetate, ii) inoculum of alloctonous sulfate-reducing bacteria and iii) treatment time. Significant changes on metal partitioning were observed in all the investigated treatments: in particular, Cu, Pb and Zn concentrations in the mobile fraction were reduced and the ones in the oxidizable fraction significantly increased. Anaerobic processes where hypothesized to lead to the formation of metal sulfides, relatively stable and less bioavailable than mobile fractions. The obtained results open new perspectives for biohydrometallurgy applied in the context of remediation strategies for sediments contaminated by heavy metals.
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Abstract: The role of Acidithiobacillus group of bacteria in acid generation and heavy metal dissolution was studied with relevance to some Indian mines. Microorganisms implicated in acid generation such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans were isolated from abandoned mines, waste rocks and tailing dumps. Arsenite oxidizing Thiomonas and Bacillus group of bacteria were isolated and their ability to oxidize As (III) to As (V) established. Mine isolated Sulfate reducing bacteria were used to remove dissolved copper, zinc, iron and arsenic from solutions.
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Authors: Jin Xiang Fu, Xiang Nan Zhang, Rong Xin Zhang
Abstract: The experiment uses the Shenyang northern sewage treatment plant two sink the pond sludge was the indigenous Thiobacillus enrichment culture, through the matrix of different proportion, to find the most suitable matrix proportion, so as to shorten the bioleaching process start time, improve the bioleaching process for heavy metal removal efficiency. By usihng the method developed by mixing S bacteria predominantly mixed bacteria liquid, will raise the mixed strain cycle was shortened to 11 days, the best ratio of S, Fe2+ matrix is determined as 3 : 1, the matrix culture mixed Thiobacillus is faster, and can greatly improve the bioleaching boot efficiency. Fe2+ dosing is able to activate the bacterial Fe2+ enzyme synthesis, be helpful for accelerating thiobacilli on s oxidation using elemental sulfur, while also promoting microorganism to use Fe2+. Using the technology of biological leaching experiment on heavy metal removal rate is higher, compared with a single strain has more engineering application and popularization value.
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