J. Lee, J. Pearlman, S. Alvarado
Colorado School of Mines,
United States
Keywords: copper sulfides, chemical leaching, bioleaching
Summary:
Global copper demand in 2050 is expected to be 60 Mt for expanding electrification and increasing renewable energy development. The amount is almost three times of current mine production and will be extremely difficult without breakthrough in copper extraction technologies. One of the promising developments is to improve copper extraction from low grade primary copper sulfide minerals, particularly chalcopyrite, covellite, and enargite. Chalcopyrite is the most abundant resource of copper and low grade materials are processed by heap or dump leaching. The typical metal extractions are not much better than 10-15% throughout the mining/extraction operations. The main reason of low recovery is due to the well known passivation on the surface. Passivation has been studied and researchers agreed that it diminishes copper recovery from primary sulfides. The causes of passivation are elemental sulfur deposit, metal deficient polysulfide formation, and jarosite precipitation. Many research efforts have tried to overcome the passivation using electrochemical approaches, but no industrial scale process was successfully demonstrated. Passivation can be avoided in when certain conditions are met resulting in improved copper extraction from the primary sulfide minerals. There are chemical methods using different leaching agents or oxidants to improve the extraction efficiency. Bioleaching using specific microorganisms is very strong candidate for copper leaching from primary sulfides while avoiding passivation. Different strains of microorganisms have been investigated under different conditions. An organic additive also showed a promising results to extract copper from sulfide concentrates or whole ore in various conditions. Copper is one of the critical materials playing an important role for technology development for electric vehicles and renewable energy. New technologies must be developed to meet these urgent demands. This talk will review the passivation phenomena and propose several process options with fundamental theory and preliminary experimental data. Chemical methods, microbiological methods, and organic additives are somewhat showed improved metal recoveries. Each process or any combination of these could play a key role for developing a groundbreaking process for increasing copper extraction and potentially meeting the global copper demand in the near future.