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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Resultados da Pesquisa
Item Biolixiviação de sulfetos secundários de cobre por Acidithiobacillus ferrooxidans.(2017) Cruz, Flávio Luciano dos Santos; Martins, Flávio Luiz; Carvalho, Liliane Coelho de; Oliveira, Víctor de Andrade Alvarenga; Leão, Versiane AlbisNeste trabalho, foi investigada a biolixiviação de sulfetos secundários de cobre com Acidithiobacillus ferrooxidans. O efeito dos parâmetros pH, concentração dos cátions Fe2+, Al3+ e Mg2+, sob a extração de cobre foram avaliados. Os experimentos em frascos agitados mostraram elevadas recuperações de cobre próximas a 75%. A cinética de extração do metal foi afetada pelo pH e concentração de Fe2+ e os valores ideais foram 1,6-1,8 e 5-10 g.L-1, respectivamente. A adição de fontes externas de alumínio (até 5 g.L-1) favoreceu a biolixiviação devido à complexação do íon fluoreto liberado durante a dissolução do mineral.Item High-temperature bioleaching of nickel sulfides : thermodynamic and kinetic implications.(2010) Cruz, Flávio Luciano dos Santos; Oliveira, Víctor de Andrade Alvarenga; Guimarães, Damaris; Souza, Adelson Dias de; Leão, Versiane AlbisThe effect of temperature on nickel sulfide bioleaching was studied in the presence of mesophile (Acidithiobacillus ferrooxidans) and moderate thermophile (Sulfobacillus thermosulfidooxidans) strains and the results were discussed in terms of sulfide dissolution thermodynamics (Eh–pH diagrams) and kinetics (cyclic voltammetry). It was observed that in the pH range 1.8–2.0 the highest nickel dissolution was achieved which reached 50% for mesophiles and over 80% for moderate thermophiles. External ferrous iron addition had no effect on the metal dissolution at 34 °C, but adversely affected nickel leaching at higher temperatures. The best outcomes were accomplished with low FeSO4 additions (2.5 g/L) at 50 °C. Pyrrhotite dissolution avoided the need for external iron addition, providing Fe2+ concentrations as high as 7 g/L during bioleaching, which supports bacterial growth. Eh–pH diagrams for pentlandite and pyrrhotite show a negligible effect of temperature on the stability field of each sulfide whilst cyclic voltammetry indicated that temperature has the strongest influence on pyrrhotite oxidation. The latter along with a rapid increase in solution potential (Eh) explains the higher and faster extraction observed with S. thermosulfidooxidans.Item Kinetics of ferrous iron oxidation by Sulfobacillus thermosulfidooxidans.(2010) Pina, Pablo dos Santos; Oliveira, Víctor de Andrade Alvarenga; Cruz, Flávio Luciano dos Santos; Leão, Versiane AlbisThe biological oxidation of ferrous iron is an important sub-process in the bioleaching of metal sulfides and other bioprocesses such as the removal of H2S from gases, the desulfurization of coal and the treatment of acid mine drainage (AMD). As a consequence, many Fe(II) oxidation kinetics studies have mostly been carried out with mesophilic microorganisms, but only a few with moderately thermophilic microorganisms. In this work, the ferrous iron oxidation kinetics in the presence of Sulfobacillus thermosulfidooxidans (DSMZ 9293) was studied. The experiments were carried out in batch mode (2L STR) and the effect of the initial ferrous iron concentration (2–20 g L−1) on both the substrate consumption and bacterial growth rate was assessed. The Monod equation was applied to describe the growth kinetics of this microorganism and values of max and Ks of 0.242 h−1 and 0.396 g L−1, respectively, were achieved. Due to the higher temperature oxidation, potential benefits on leaching kinetics are forecasted.Item Manganese and limestone interactions during mine water treatment.(2010) Silva, Adarlêne Moreira; Cruz, Flávio Luciano dos Santos; Lima, Rosa Malena Fernandes; Teixeira, Mônica Cristina; Leão, Versiane AlbisManganese removal from mining-affected waters is an important challenge for the mining industry. Addressed herein is this issue in both batch and continuous conditions. Batch experiments were carried out with synthetic solutions, at 23±2 ◦C, initial pH 5.5 and 8.3 g limestone/L. Similarly, continuous tests were performed with a 16.5 mg/L Mn2+ mine water, at 23 ◦C, initial pH 8.0 and 20.8 g limestone/L. Calcite limestone gave the best results and its fine grinding proved to the most effective parameter for manganese removal. In either synthetic solutions or industrial effluents, the final manganese concentration was below 1 mg/L. A change in limestone surface zeta potential is observed after manganese removal and manganese carbonate formation was suggested by IR spectroscopy. The conclusion is that limestone can remove manganese from industrial effluents for values that comply with environmental regulations.