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 Column bioleaching of fluoride-containing secondary copper sulfide ores : experiments with Sulfobacillus thermosulfidooxidans.(2019) Rodrigues, Michael Leonardo Marques; Santos, Guilherme H. A.; Leôncio, Hamilton Cristiano; Leão, Versiane AlbisBioleaching is a mature technology, which is widely employed commercially in the leaching of primary sources of metals (ores, concentrates, and mine residues). The current work discussed the effects of aluminum sulfate additions to the growth medium, PLS recirculation and bleeding on the column bioleaching of secondary copper sulfide ores with a significant content of fluoride-containing minerals. Fluoride is toxic to bacteria at the pH of bioleaching but its toxicity may be overcome in the presence of soluble aluminum and ferric iron. Therefore, experiments were carried out in 10 × 100 cm height aerated columns, loaded with 10 kg of crushed and agglomerated copper ore and inoculated with Sulfobacillus thermosulfidooxidans. Initially, fluoride concentrations of up to 2.5 g/L in the pregnant leach solution were observed due to the fast dissolution of fluoride-bearing minerals. Aluminum was added to the leaching solution to reduce the Al/F ratio so that the concentration of HF (the main toxic species) was decreased, but while the total fluoride concentration was higher than that of aluminum, the bacterial population as low. Therefore, the current work emphasizes that it is possible to set up conditions to enable bioleaching even at high fluoride concentrations. Following this approach, copper extractions above 90% were achieved for a H2SO4 consumption ranging from 128.8 to 206.1 Kg/ton.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.