Calcopyrite (CuFeS2) oxidation studies by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans

• Grant number: 08/04381-0
• Support Opportunities: Scholarships abroad - Research
• Start date: August 20, 2008
• End date: January 19, 2009
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Oswaldo Garcia Junior
• Grantee: Oswaldo Garcia Junior
• Host Investigator: Jaakko Puhakka
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Institution abroad: Tampere University of Technology (TUT), Finland

Abstract

Bacterial leaching is a dissolution process of metal sulfides in which the oxidative activity of some bacterial species, mainly Acithiobacillus ferrooxidans, play a central role. Since the finding of this and other microorganisms participation in the "natural" leaching of metals from low-grade ores (1950s) several industrial applications has been set up and a huge number of works about this emerging biotechnology has been published. Among the metals, copper is the oldest bioleaching industrial application and the most studied, even so uranium, gold and nickel are also other examples of industrial applications. Chalcopyrite (CuFeS2) is one of most important worldwide reserve of copper sulfide, but at same time the most refractory to the both, chemical and bacterial attack. Regarding to bacterial oxidation, this mineral presents slow rates of dissolution, being final efficiency much lower than the minimum desired. Several studies of process engineering, biochemistry and molecular biology have been published, but few practical results are obtained. Only recently, the phenomenon of cellular attachment to the sulfides and the electrochemical and molecular mechanisms involved in this aspect, have deserved more attention. So, our research group has developed integrated studies in this route, which can, in our point of view, to bring up new insights to the knowledge of chalcopyrite refractory nature, toward an improvement in the solubilization efficiency. The research group of Tampere University of Technology-TUT (Finland), within in a large project of European Union ("BioMinE"), is also developing similar studies. Due to the expertise of both research groups, the central goal of our visit to the TUT is to carry out some studies in this area, as a collaborative action between two research teams that are intensely involved in the field. This cooperation can bring up important results to understand and optimize the chalcopyrite dissolution by bacteria. (AU)