Bioleaching of a Spanish complex sulphide ore bulk concentrate

In the present work the applicability of bioleaching using a mixed culture of mesophilic microorganisms (Thiobacillus ferrooxidans, Thiobacillus thioo xidans and Leptospirilum ferrooxidans) on a bulk concentrate of a Spanish c omplex sulphide ore was studied. The bulk concentrate mainly consisted of b y chalcopyrite, sphalerite and pyrite. Effects of nutrient medium, stirring , pulp density, temperature and the addition of CO2 (1% v/v) to the airflow were also studied. The highest leaching rates and recoveries were obtained with mechanically stirred reactors at 5% pulp density and 9K medium. Howev er, by using 9K medium higher jarosite precipitation was observed. Results showed that the optimum temperature for copper bioleaching was 30 degrees C , whereas zinc dissolution increased with a rise in the temperature. (C) 19 98 Elsevier Science Ltd. All rights reserved.