The economic importance of copper production worldwide makes it necessary to develop and improve technologies to obtain this precious metal. In particular, chalcopyrite (CuFeS2) is the most abundant copper mineral in nature, representing approximately 70% of the world’s copper reserves.
Traditionally, chalcopyrite has been treated by pyrometallurgical methods. However, the pursuit of a biohydrometallurgical method as an alternative to smelting presents important advantages such as the possibility of treating low-grade minerals (which are increasingly abundant in the case of copper).
Although, most of the secondary copper sulfides, such as chalcocite, covelite, bornite, etc. can be successfully bioleached by mesophilic microorganisms, in the case of primary copper sulphides (such as chalcopyrite) they remain a major challenge for bioleaching due to their highly refractory character under hydrometallurgical conditions and a passivating layer hinders direct contact between the solution and the mineral.
Blasting at Gabriela Mistral Mine. Codelco, Chile.
Having said this, in the first stage of this project it has been proposed to evaluate microorganisms belonging to the Bacteria and Archaea domains in their ability to maintain the redox potential of a chalcopyrite bioleaching system in the favorable range for copper dissolution.
In the last nine months it has been possible to evaluate different candidate strains on a laboratory scale, among the experiments that have been carried out have evaluated iron and/or sulfur oxidizer strains in a temperature range between 30 to 70°C, the experiments have been carried out using the microorganisms individually as well as in co-cultures. After completing this stage, it will be possible to select the most suitable strains for the next stage of this project, which consists of designing microbial communities and evaluating their ability to bioleach chalcopyrite.