Bioprocessing low grade copper ores - a promising alternative
Résumé
This paper presents an overview of the work performed by the BRGM team in the last 10 years on the development of bio-hydrometallurgy dedicated to the processing of low-grade copper ores from the Kupferschiefer deposits. It covers selection and adaptation of microbial consortia, optimization of process operating parameters such as solid contents, the relationship between bioleaching performance and mineralogy, testing operating parameters to overcome chalcopyrite recalcitrance, design of process options and economical assessment. The selected bacterial inoculum (autotrophic, working at 42°C) enables to achieve high Cu recovery (up to 95%). In continuous piloting tests the increase of the solid load in the pulp from 15% to 25% doesn’t affect the bioleaching efficiency despite the high and unusual Cu concentration reached in the liquor (40 g l-1). Operating at 25% solid load reduces by 2.3 the size of the leaching tanks compared to 15% solid load, which leads to a significant decreasing of the CAPEX.