Characterization of Cu-SiO 2 Composite Synthesized by Hydrogen Reduction of Chalcopyrite Concentrate Followed by Acid Le
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aditional route of copper making from chalcopyrite ore/concentrate involves a number of pyrometallurgical processing steps, such as roasting, smelting, converting, and refining, which makes the overall process lengthy and time consuming. As an alternative route, chalcopyrite concentrates can be directly reduced by hydrogen. Although much study has been conducted on the hydrogen reduction of copper sulfides such as chalcocite (Cu2S) and chalcopyrite (CuFeS2),[1–4] the sulfides used in most cases were synthetic (pure) reagents, not natural ores or their concentrates. Moreover, in order to facilitate the removal of the product gas
RITAYAN CHATTERJEE, Graduate Student, and DINABANDHU GHOSH, Professor, are with the Department of Metallurgical and Materials Engineering, Jadavpur University, Kolkata 700032, India. Contact e-mail: [email protected] Manuscript submitted May 17, 2012. METALLURGICAL AND MATERIALS TRANSACTIONS B
(H2S), lime (CaO) was used in most cases. However, the handling of CaO, which is a strongly hygroscopic substance, may pose problem. Hydrogen reduction of chalcopyrite concentrate (containing primarily the ore mineral CuFeS2 and gangue mineral SiO2) in absence of lime has not been attempted so far, which can be a more challenging and useful research from the industrial point of view. The objective of the current study was to synthesize copper-silica (Cu-SiO2) mixture/composite by the hydrogen reduction of chalcopyrite concentrate without using any flux such as lime, followed by acid leaching. Subsequently, Cu was to be separated from the SiO2 (presumably by a simple method of melting and decantation) to complete the extraction of copper from the chalcopyrite concentrate. However, the current article deals with only the first part of the objective, i.e., the synthesis of a Cu-SiO2 composite, along with the phase identification and microstructural characterization of the synthesized product. A few words may be said here about the importance of Cu-SiO2 composites and the different studies recently carried out on their syntheses and properties. Cu-SiO2 composites exhibit interesting optical, electrical, and magnetic properties. Also, depending upon the fineness of the grains, they may be used as catalyst for some applications.[5] Yeshchenko et al.[6] synthesized Cu-SiO2 nanocomposites and reported that the melting of spherical copper nanoparticles embedded in a silica matrix is size dependent. Cu-SiO2 composites have also been synthesized by Kim et al.[7] following the wellknown Stober method and carried out an optical characterization of the composite. Copper-silica composite coatings are an attractive alternative to chromium and nickel coatings to avoid environmental problems and for application in electrical devices.[8] In many recent studies, considerable attention has been given to creating core–shell composites using SiO2 as the shell. The SiO2 shell can give significant modifications to the cores with respect to their physical properties such as optical capabilities and biocompatibility as well as environm
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