BIOLEACHING OF COPPER FROM CARAIBA MINE ORE (BRAZIL)

The bioleaching of copper ore from the Caraiba Mine was assessed. A microorganism, Acidiothiobacillus ferrooxidans, was isolated from samples collected directly in acid mining drainage in a gold mine tailings pound and used in the bioleaching of the copper sulfide ore. This ore is composed mainly of 28% of oxidized species, 43% of secondary sulfides and 24% of primary sulfide. The shaking flasks experiments with the Caraiba ore showed copper chemical leaching of about 37% and copper bioleaching of about 60% within 60 days at low temperature and native microorganism.

Treatment of Acid Mine Drainage by Sulfate Reducing Bacteria and Iron at Room Temperature

This study describes a new method to treat acid mine wastewater containing high amounts of heavy metals and sulfate by biotechnology. Sulfate reducing Bacteria (SRB) was inoculated in an up-flow multiple bed bioreactor treating practical wastewater. In addition to precipitation processes, water purification was also possible with the metabolism process of microorganisms. Iron dust was added to the system to enhance the activity of SRB and ensure the treatment efficiency. The results indicates that treating acid mining drainage using SRB and iron at room temperature (20°C~25°C) is possible, the reduction rate of sulfate is up to 61%, pH of wastewater raises from 2.75 to 6.2 and the copper concentration of effluent is less than 0.2 mg/L.