Biohidromeyalurgia

Biohidrometalurgia

Acidithiobacillus ferrooxidans Bastonetes Gran-

• Acidofílico (pH: 1.0 a 4.0) • Quimiolitotrófico (fixa CO2 através do Ciclo de Calvin) • Fonte de energia (Fe2+ e formas reduzidas de enxofre, incluindo sulfetos metálicos) • Habitat natural (água ácida de mina) Lixiviação de cobre

Química Nova Print ISSN 0100-4042
Quím. Nova vol.25 no.1 São Paulo Jan./Feb. 2002

Artigo APLICAÇÃO DE TÉCNICAS ELETROQUÍMICAS NO ESTUDO DA DISSOLUÇÃO OXIDATIVA DA COVELITA (CUS) POR THIOBACILLUS FERROOXIDANS
Christiane Medina Teixeira, Ivan Ramires, Oswaldo Garcia Júnior e Antonio Carlos Guastaldi* Instituto de Química, Universidade Estadual Paulista, CP 355, 14801-970 Araraquara SP *e-mail: [e-mail] Recebido em 26/9/00; aceito em 6/7/01 ELECTROCHEMICAL TECHNIQUES APPLIED TO STUDY THE OXIDATIVE DISSOLUTION OF THE COVELLITE - CuS by THIOBACILLUS FERROOXIDANS. Among the copper sulphides, chalcopyrite (CuFeS2), covellite (CuS) and chalcocite (Cu2S) are the most important source of minerals for copper mining industry. The acknowledge of behaviour of these sulphides related with bacterial leaching process are essential for optimization procedures. Despite of its importance, covellite has not deserved much interest of researchers regarding this matter. In this work it was studied the oxidation of covellite by the chemolithotrophic bacterium Thiobacillus ferrooxidans by using electrochemical techniques, such as open circuit potentials with the time and cyclic voltammetry. The experiments were carried out in acid medium (pH 1.8), containing or 2+ not Fe as additional energy source, and in different periods of incubation; chemical controls were run in parallel. The results showed that a sulphur layer is formed spontaneously due the acid attack, covering the sulphide in the initial phase of incubation, blocking the sulphide oxidation. However, the bacterium was capable to 2+ oxidize this sulphur layer. In the presence of Fe as supplemental energy source,