Bioleaching of fluoride-bearing secondary copper sulphides: Column experiments with Acidithiobacillus ferrooxidans
| Autor: | Hamilton Cristiano Leôncio, Klinger Carlos Silva Lopes, Michael Leonardo Marques Rodrigues, Larissa A.M. Silva, Versiane Albis Leão |
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| Rok vydání: | 2016 |
| Předmět: |
inorganic chemicals
General Chemical Engineering Metallurgy chemistry.chemical_element 02 engineering and technology General Chemistry Copper Industrial and Manufacturing Engineering 020501 mining & metallurgy chemistry.chemical_compound 0205 materials engineering chemistry Fluoride toxicity Aluminium Bioleaching Environmental Chemistry Gangue Leaching (metallurgy) Dissolution Fluoride Nuclear chemistry |
| Zdroj: | Chemical Engineering Journal. 284:1279-1286 |
| ISSN: | 1385-8947 |
| DOI: | 10.1016/j.cej.2015.09.020 |
| Popis: | Bioleaching is a mature technology, which is widely employed commercially in the leaching of low-grade secondary copper sulphide ores. In this work, the bioleaching potential of a low-grade (marginal) ore with a significant content of fluoride was assessed. Small columns were inoculated with a strain of At. ferrooxidans, at 30 °C, and resulted in copper extractions above 89%, in 255 days. The dissolution of fluorite from the gangue minerals accounted for up to 2.5 g/L fluoride in solution, which affected bioleaching shortly after column inoculation. However, both the released of aluminium from the ore and ferric iron production by the bacteria reduced fluoride toxicity. A fluoride-toxicity parameter (η) was proposed to represent the mass ratio between total fluoride, total aluminium and total ferric iron concentrations in the system. Low values of the η parameter resulted from high ferric iron and aluminium concentrations and implied in large bacterial population in the systems. Thus, the presence of fluoride-bearing minerals in the ore may be an important issue, but the content of both cations should be also considered. Despite the absence of ferric iron and a high fluoride concentration prior to first solution bleeding, the η parameter was lower than 0.3 in the column containing an external aluminium source. In this condition, as the aluminium content surpassed that of fluoride the bacterial population reached 107 cells/mL and enabled copper bioleaching. |
| Databáze: | OpenAIRE |
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