Separation of Arsenic from the Antimony-Bearing Dust through Selective Oxidation Using CuO
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THE reserve amount of antimony in the world is higher than 2 million tons, most of which is found in China, Bolivia, Russia, South Africa, and Tajikistan.[1,2] Among them, China has the most abundant antimony resource and the current mine production is about 100,000 t/year.[3,4] However, the uncontrolled exploitation will result in it being depleted in 10 years. It is necessary to find other resources to extract antimony, in addition from the ore. There is an antimony-bearing dust generated in many pyrometallurgical processes, which also contains other valuable metals, such as lead, antimony, and indium.[5–8] Nevertheless, arsenic, a toxic element companioned with antimony,[9–12] reduces the antimony product quality if it is not removed.[13–15] In addition, this dust cannot be directly recycled to the smelters or converters because of the increase of required energy for the smelting or converting process. It is necessary to treat the dust separately to recover valuable metals. The conventional treatment of antimony-bearing dusts can be classified into two methods: pyrometallurgical[11,16–19] and hydrometallurgical processes. The pyrometallurgical process generally involves oxidizing roasting, reduction roasting, and chlorination roasting. The As2O3 is easy to volatilize due to its strong volatility, as a result of which the volatilization rate of it exceeded 93 mass pct in 120 minutes at 733 K (460 °C) DA-PENG ZHONG, LEI LI, and CHENG TAN are with the State Key Laboratory of Complex Non-ferrous Metal Resources Clean Utilization, Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction of Ministry of Education, Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, P.R. China. Contact e-mail: [email protected] Manuscript submitted July 20, 2016. Article published online January 11, 2017. 1308—VOLUME 48B, APRIL 2017
in one study.[20] The Sb2O3 volatilizes in the form of Sb4O6 (g), and its volatilization rate outstrips 95 mass pct in 140 minutes at 873 K (600 °C) under nitrogen atmosphere.[21] However, at a special oxygen concentration (higher than 10 pct), Padilla et al.[22] found that antimony volatilization was inhibited by the formation of a nonvolatile compound, SbO2. In the presence of As2O3, the Sb2O3 would be transformed into a heteronuclear compound AsxSbyO6 (where x = 1, 2, or 3, and x + y = 4) during the roasting process, and it would inhibit the arsenic volatilization and simultaneously promote antimony volatilization at 473 K to 1073 K (200 °C to 800 °C).[17,23,24] Tang et al.[18] and Li et al.[19] researched the separation of arsenic from high arsenic-antimony dusts under N2-O2 mixed atmospheres, the results of which showed that less than 61 mass pct of arsenic and higher than 9 mass pct of antimony volatilized into gas phases. It is difficult to separate arsenic and antimony through traditional pyrometallurgical processing, since As2O3 and Sb2O3 are both easy to volatilize in inert atmosphere and oxidize in a
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