EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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2 resultados
Resultados da Pesquisa
Item Assessing metal recovery from low-grade copper ores containing fluoride.(2011) Sicupira, Lazaro Chaves; Veloso, Tácia Costa; Gonzaga, Flávia Donária Reis; Leão, Versiane AlbisLow-grade ores are becoming increasingly important to metal production due to increasing metal prices and depletion of high-grade, low-impurity sources. Bioleaching can be an option to recover the metallic content present in these tailings. In this work, the bioleaching potential of a low-grade copper ore, containing chalcocite, bornite and chalcopyrite, was demonstrated with a Sulfobacillus thermosulfidooxidans strain, at 50 °C. Batch experiments were performed in shake flasks as well as a bioreactor (BioFlo 110), and the effects of pH, metal concentration and air flow rate on copper extraction were determined. The presence of fluoride in the gangue minerals resulted in up to 270 mg/L total fluoride in solution, which affected bioleaching. Fluoride toxicity was overcome with aluminium additions and resulted in high copper extraction (up to 100%) at pH 1.9. Speciation calculations were performed with on the aluminium-fluoride systems and indicated AlF2+ as the main complex in the system, whereas HF concentration was reduced to values below 10−4 mol/L, which seems to be the threshold for bacterial growth inhibition.Item The effects of fluoride and aluminum ions on ferrous-iron oxidation and copper sulfide bioleaching with Sulfobacillus thermosulfidooxidans.(2012) Veloso, Tácia Costa; Sicupira, Lazaro Chaves; Rodrigues, Isabel Cristina Braga; Silva, Larissa A. M.; Leão, Versiane AlbisMicroorganisms that grow at high temperatures can improve Fe(II) bio-oxidation and thereby its technological applications, such as bioleaching and H2S removal. Conversely, elements present in industrial growth media, such as fluoride, can inhibit bacterial growth and iron bio-oxidation. In this work, the influence of fluoride on the kinetics of ferrous-iron bio-oxidation with Sulfobacillus thermosulfidooxidans was investigated. The effects of fluoride concentrations (0–0.5 mmol L−1) on both iron oxidation and bacterial growth rates were assessed. In addition, the effect of the addition of aluminum, which was intended to complex free fluoride and reduce the concentration of HF through the formation of aluminum–fluoride complexes, was also investigated. The results show that 0.5 mmol L−1 NaF completely inhibited bacterial growth within 60 h. Nevertheless, fluoride toxicity to S. thermosulfidooxidans was minimized by control of the aluminum–fluoride ratio in the system because, at a 2:1 aluminum–fluoride molar ratio, bacterial growth was similar to that observed in the absence of fluoride ions. Despite a slower bacterial growth rate, fluoride concentrations less than the inhibitory concentration increased the Fe(II) oxidation rate. Successful copper bioleaching (80–100%) from fluoride-containing sulfide ores (1% total fluoride) was demonstrated in the presence of aluminum.