Acidic dissolution of chalcopyrite in the presence of ferric ion is a scientific challenge that is the subject of research by many researchers. The role of pyrite has also been studied as catalyst and enhancer of chalcopyrite leaching. Previous studies have shown the ch More
Acidic dissolution of chalcopyrite in the presence of ferric ion is a scientific challenge that is the subject of research by many researchers. The role of pyrite has also been studied as catalyst and enhancer of chalcopyrite leaching. Previous studies have shown the chalcopyrite electrochemical leaching in the presence of oxidants, and oxidation-reduction reactions depend on reaction environmental conditions. In this paper, in addition to electrochemical techniques (cyclic voltammetry and chronoamprometry), mathematical calculations and thermodynamic equations have been used to investigate the effect of ferric ion and pyrite on oxidation-reduction reactions of chalcopyrite. First, the oxidation-reduction reactions of chalcopyrite surface by cyclic voltammetry in acidic medium and then the effect of ferric ion addition on these reactions have been investigated. Then effect of pyrite presence along with the ferric ion (pyrite / ferric ion) is studied by the above method. The results of cyclic voltammetry method showed that ferric ion and pyrite increased the anodic and cathodic peak intensities and had a positive effect on chalcopyrite surface reactions. Also results of chronoamprometry and thermodynamic studies showed increase of free energy of chalcopyrite oxidation reaction in the presence of pyrite which was -22.45 kJ/mol.
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Background & Objectives: Dissolution of chalcopyrite is one of the most important challenges of hydrometallurgy because it is difficult to leach due to its inactivation by passive precipitates like jarosites. The combination of the benefits of microbial leaching (na More
Background & Objectives: Dissolution of chalcopyrite is one of the most important challenges of hydrometallurgy because it is difficult to leach due to its inactivation by passive precipitates like jarosites. The combination of the benefits of microbial leaching (native mesophiles, moderate thermophiles, and extreme thermophiles), and chloride leaching was the main purpose to enhance the copper recovery, especially from the low-grade chalcopyrite sources. Materials & Methods: The native microorganisms were isolated from Sarcheshmeh mine, and adapted (4 months with chloride media). Then, the bioleaching operation was systematically performed using the columns containing low chalcopyrite ore (less than 0.3% Cu) to investigate the effect of the chlorine on the bioleaching process. Different analyzes of the leaching and feed residues were used to closely examine the process and mechanisms involved (A 23% increase in recovery (81% with chlorine and 58% with no chlorine)). Results: Based on the analyses of the bio-leaching residues, overcoming the problems caused by the unwanted precipitates like jarosite during chlorinated bioprocess (2 g / l chloride) was one of the main reasons for these results which were identified using SEM, EDS analysis. And, the elemental mapping of the solid residues from microbial leaching operations proved this possible reason. Conclusion: Controlling the undesirable precipitates in the process was the most important lever to improve copper recovery (more than 81% of copper over 120 days). This was achieved by regulating the growth process and activity of microorganisms from mesophiles to extreme thermophiles with sodium chloride salt additive.
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In this research, chlorination of chalcopyrite in a low-energy mill was carried out in order to convert chalcopyrite to copper chloride. Chalcopyrite milling was performed at ambient temperature and in different times and dry chlorine gas atmosphere. Also, chlorination More
In this research, chlorination of chalcopyrite in a low-energy mill was carried out in order to convert chalcopyrite to copper chloride. Chalcopyrite milling was performed at ambient temperature and in different times and dry chlorine gas atmosphere. Also, chlorination process was combined by mechanoleaching using different solvents at different times. X-ray diffraction analysis was used to identify the phases formed in the samples. X-ray diffraction pattern of milled chalcopyrite powders showed that in the low-energy milling, after a specified time, chalcopyrite is converted to chloride of iron, copper and sulfur. Scanning electron microscope images were obtained to evaluate the products morphology and reaction kinetics. Eventually, after 20 hours milling, about 60 percent of chalcopyrite were converted into chlorides.
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