Abstract
Chalcocite is the most abundant secondary copper sulfide globally, with the highest copper content, and is easily treated by conventional hydrometallurgical processes, making it a very profitable mineral for extraction. Among the various leaching processes to treat chalcocite, chloride media show better results and have a greater industrial boom. Chalcocite dissolution is a two-stage process, the second being much slower than the first. During the second stage, in the first instance, it is possible to oxidize the covellite in a wide range of chloride concentrations or redox potentials (up to 75% extraction of Cu). Subsequently, CuS2 is formed, which is to be oxidized. It is necessary to work at high concentrations of chloride (>2.5 mol/L) and/or increase the temperature to reach a redox potential of over 650 mV, which in turn decreases the thickness of the elemental sulfur layer on the mineral surface, facilitating chloride ions to generate a better porosity of this. Finally, it is concluded that the most optimal way to extract copper from chalcocite is, during the first stage, to work with high concentrations of chloride (50–100 g/L) and low concentrations of sulfuric acid (0.5 mol/L) at a temperature environment, as other variables become irrelevant during this stage if the concentration of chloride ions in the system is high. While in the second stage, it is necessary to increase the temperature of the system (moderate temperatures) or incorporate a high concentration of some oxidizing agent to avoid the passivation of the mineral.
Highlights
Most of copper minerals correspond to sulfide minerals and a minor part to oxidized minerals
Regarding the acid concentration in a sulfate–chloride system, the findings presented by Dutrizac [69], Cheng and Lawson [24], Senanayake [45], Toro et al [13], Saldaña et al [44], and Torres et al [46] confirm that the concentration of chloride ions in the system is the variable that most influences the kinetics of the dissolution of chalcocite at room temperature, making other operational variables, such as acid concentration, particle size, stirring speed, etc., less relevant
In the study conducted by Hashemzadeh et al [63], the researchers modeled the dissolution kinetics of Cu2 S in chloride media using leaching data obtained under fully controlled temperature, pH, and solution potential
Summary
Most of copper minerals correspond to sulfide minerals and a minor part to oxidized minerals. Chalcocite has a dark gray color and belongs to the copper-rich mineral family ranging from CuS to Cu2 S (see Table 1), commonly found in the enriched supergenic environment below the oxidized zone of copper porphyry deposits [15,16,17,18,19] This is formed by oxidation, reduction, dissemination, and migration of primary sulfides. Among the different leaching media to treat secondary copper sulfides, chloride media has had the greatest growth at an industrial level This is due to the good results presented by chloride media in heap leaching processes and due to freshwater shortage. A bibliographic review based on scientific publications in recent years on chalcocite leaching in chloride media is carried out in the present manuscript. Chalcocite, comparing the impact that each one has on the extraction of copper from it
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