Chalcopyrite (CuFeS2) is the most refractory copper mineral when treated in conventional sulfate media leaching systems. This is the first study to examine the use of a dimethyl sulfoxide (CH3SOCH3, DMSO) solution containing copper chloride (CuCl2) for the leaching of chalcopyrite. Leaching experiments for a copper concentrate composed mainly of chalcopyrite were conducted at ambient pressure at 313–413 K. The leaching fractions of Cu, Fe, S, Au, and As were investigated. It was found that 90% of the Cu was extracted in 2 h, and 94% was extracted in 4 h at 373 K, which is competitive with other conventional processes. A DMSO solution containing CuCl2 could selectively dissolve the valuable metals Cu and Au from chalcopyrite, but leave minerals with little economic value such as pyrite (FeS2) and As in the residue. Chalcopyrite is oxidized by cupric ion in proportion to the stoichiometric ratio of Cu in the concentrate to the initial cupric ion in the DMSO solution, which is enhanced by the presence of oxygen below 373 K.
We have developed a novel process for recycling gold (Au) from secondary sources: the leaching of gold using Organic Aqua Regius, e.g. dimethyl sulfoxide (DMSO) or propylene carbonate (PC) solutions containing copper bromide (CuBr 2) and potassium bromide (KBr) , which could offer a number of advantages, including eco-friendliness and ease of operation. In this study, we applied PC solution to recover Au from Waste Electric and Electronic Equipment (WEEE). First, the WEEE samples (memory card, mobile phone board and small appliances) were coarsely grinded and finely grinded. Then, thermal activation of semiconductors (TASC) technology using TiO 2 was applied to decompose the polymers and oxidize base metals containing in WEEEs. Next, the leaching of Au from the oxidized samples were conducted in a PC solution with 0.2 M of CuBr 2 and 0.2 M of KBr, at 353-373 K, followed by biphasic separation with sulfuric acid. The dissolved Au in the PC phase was recovered by reduction of ascorbic acid. The recover y ratio of Au was 56.0% , 67.2% and 65.7% from memor y card, mobile phone board and small appliances, respectively.
We conducted experiments using unit processes to prove the feasibility of the concept of an environmentally sound Au recovery process from waste electrical and electronic equipment (WEEE) using organic aqua regia, i.e., a propylene carbonate (PC) solution containing CuBr2 and KBr. First, the WEEE samples (memory card and mobile phone board) were finely ground. The samples were then carbonized and oxidized to decompose the polymers and oxidize the base metals. The leaching of Au from the oxidized samples was then carried out in a PC solution with 0.2 M of CuBr2 and 0.2 M of KBr over 353–373 K, followed by biphasic separation with sulfuric acid. The dissolved Au in the PC phase was recovered via ascorbic acid reduction. The mass balance of Au in the leaching was investigated. The maximum recovery ratios of Au from the memory card and mobile phone board were 79% and 83%, respectively. The cost of leaching was preliminarily estimated.
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