Impact of Anode on Product Formation During the Electrochemical Reduction of Chalcopyrite
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https://doi.org/10.1007/s11837-020-04100-z Ó 2020 The Minerals, Metals & Materials Society
ELECTROMETALLURGICAL PROCESSING
Impact of Anode on Product Formation During the Electrochemical Reduction of Chalcopyrite CAMPBELL A. DONNELLY,1 JONATHAN T. VARDNER,1 ZHENGYAN ZHANG,1 SCOTT BANTA,1 and ALAN C. WEST1,2,3 1.—Department of Chemical Engineering, Columbia University, New York, NY 10027, USA. 2.—Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA. 3.—e-mail: [email protected]
A hydrometallurgical process has been demonstrated to electrochemically convert chalcopyrite (CuFeS2) to less refractory mineral phases for subsequent chemical oxidation. The electrochemical reaction mechanisms are not well understood; consequently, researchers have been unable to improve the process. In this study, the bulk and surface phases of the chalcopyrite mineral during the progression of the electrochemical reactions are monitored using xray diffraction and x-ray photoelectron spectroscopy, respectively. The results suggest that chalcopyrite reacts at the cathode of the electrochemical reactor to release iron and form an intermediate chalcocite (Cu2S) mineral phase. Allowing Cu2S to contact the anode leads to the formation of covellite (CuS), whereas preventing the mineral from anode contact leads to the formation of cuprite (Cu2O). It was shown that copper ions are more easily extracted from Cu2O than CuS; therefore, it may be desirable to isolate the anode from mineral contact during the electrochemical process.
INTRODUCTION The superior electrical and thermal conductivity of copper makes it a key component in energy efficient materials for the twenty-first century. For instance, a hybrid vehicle contains approximately 45 kg of copper in its wiring, motors, radiators, and brakes.1 The high demand for copper is coinciding with a sharp decline in the grade of copper reserves; as a result, the cost of copper production is expected to escalate in the coming decades. Researchers project a global peak in the copper industry by the year 2050 due in part to the high costs of copper production.2 The development of new processing techniques of copper-containing ore is important to reduce the costs of copper production and extend the availability of new copper for several decades. Chalcopyrite (CuFeS2) is the most abundant copper-containing mineral found in nature, accounting for approximately 70% of global copper reserves. The CuFeS2 mineral is typically mined, concentrated, and then smelted to produce copper.3 The pyrometallurgical process is characterized by high investment costs, high operating costs, and the potential release of environmentally deleterious by-
products such as sulfur dioxide and arsenic. Thus, there is substantial interest in pursuing the hydrometallurgical processing of CuFeS2 to lower the costs and environmental impact of future copper production. The hydrometallurgical leaching of CuFeS2 is generally conducted with Fe3+ as the oxidant,4,5 although reagents such as O26 an
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