Chalcopyrite bioleaching in chloride media: A mini-review

The growing worldwide demand for copper implies the need to process increased amounts of its ores. Chalcopyrite is the most abundant copper mineral, but due to its refractory nature it presents slow kinetics and low metal recovery when submitted to hydrometallurgical processes. Researchers have proposed the application of high temperatures and the use of reagents such as sodium chloride in order to overcome such refractoriness. Within hydrometallurgy, bioleaching has been suggested as an economic and environmental alternative to traditional chemical processes. However, most acidophilic microorganisms used in bioleaching cannot tolerate high chloride concentrations - similar to those found in seawater. Therefore, this review aims to present the main aspects of these systems, as the application of chloride in bioleaching is still a challenge. Nevertheless, if this problem is overcome, chloride bioleaching can become an alternative to process low grade chalcopyrite- bearing ores and tailings, particularly when saline waters are used in bioleaching processes to reduce the demand for fresh water.