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 Effect of iron in zinc silicate concentrate on leaching with sulphuric acid.(2009) Souza, Adelson Dias de; Pina, Pablo dos Santos; Santos, Fabiano Mariel Fernandes dos; Silva, Carlos Antônio da; Leão, Versiane AlbisIt is shown that the iron content in zinc silicate concentrates with either high (8–11%) or low (3%) iron does not significantly affect the kinetics or overall recovery of zinc extraction in sulphuric acid. Most of the iron was present as hematite and franklinite with little iron contained in willemite. A small reduction in zinc recovery from 98.5% to 97.5% was observed for silicate ores containing 12% iron. The activation energy determined from high-iron concentrate leaching, 78±12 kJ/mol, is statistically similar to that from low-iron concentrate, 67±10 kJ/mol, suggesting the same rate-controlling step. The leaching of high high-iron concentrates enables a higher mass recovery during flotation. A flowsheet is proposed comprising a magnetic separation step to produce a magnetic and a non-magnetic product so that iron dissolution from the magnetic concentrate acts as a source of soluble iron for impurities removal.Item A kinetic study of the sulphuric acid leaching of a zinc silicate calcine.(2007) Souza, Adelson Dias de; Pina, Pablo dos Santos; Lima, Ermani Vinicius de Oliveira; Silva, Carlos Antônio da; Leão, Versiane AlbisRecent developments of acid leaching and solvent extraction of zinc silicate ores have produced renewed commercial interest. However, the leaching kinetics of these concentrates has received little attention. This work, therefore, addresses the leaching of a zinc silicate concentrate in sulphuric acid. The effects of particle size (0.038–0.075mm), temperature (30–50°C) and initial acid concentration (0.2–1.0mol/L) were studied. The results show that decreasing the particle size while increasing the temperature and acid concentration increase the leaching rate. As leaching occurs, there is a progressive dissolution of willemite whil e the quartz and iron-containing phases remain inert. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control successfully described the zinc leaching kinetics. The model enabled the determination of an activation energy of 51.9 ± 2.8kJ/mol and a reaction order of 0.64 ± 0.12 with respect to sulphuric acid, which are likely to be a consequence of the parallel nature of diffusion and chemical reaction in porous solids.