Separation and Extraction of Valuable Metals from Electroplating Sludge by Carbothermal Reduction and Low-Carbon Reducti
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https://doi.org/10.1007/s11837-019-03880-3 2019 The Minerals, Metals & Materials Society
CLEANER MANUFACTURING OF CRITICAL METALS
Separation and Extraction of Valuable Metals from Electroplating Sludge by Carbothermal Reduction and Low-Carbon Reduction Refining LEI TIAN,1,4 LIJIE CHEN,1 AO GONG,1 XUANGAO WU,1 CAIFANG CAO,1 DUDAN LIU,2,3 ZHI-QIANG CHEN,2,3 ZHI-FENG XU,1,5 and YONG LIU2,3,6 1.—School of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China. 2.—Guangdong Institute of Resources Comprehensive Utilization, Guangzhou 510000, China. 3.—State Key Laboratory of Rare Metals Separation and Comprehensive Utilization, Guangzhou 510000, China. 4.—Henan Yuguang Gold and Lead Group Co., Ltd., Jiyuan 454650, China. 5.—e-mail: [email protected]. 6.—e-mail: [email protected]
This paper proposes an innovative carbothermal reduction roasting low-carbon redox refining process for recovering valuable metals, including copper, zinc, nickel, tin and lead, from electroplating sludge. First, the valuable metals are volatilized into the flue gas by carbothermal reduction roasting. At a reduction temperature of 1473 K, a carbon content of 20%, and a reaction time of 60 min, the ratio of Pb, Sn and Zn removal reached 90.77%, 95.14% and 99.92%, respectively. At an oxidation temperature of 1573 K, a SiO2 content of 6% and a reaction time of 180 min, a water-quenching slag suitable for building materials was obtained by low-carbon oxidation reduction refining. Finally, at a reduction temperature of 1473 K, 8% C addition, and a reaction time of 20 min, copper and nickel were enriched on an anode copper plate and the copper content reached more than 98%, meeting the requirements for copper electrolysis.
INTRODUCTION As a waste product of the metallurgical and chemical industry, copper sludge is included on the national hazardous waste list.1 Although the amount of copper sludge produced is much less than that of wastewater, in the ‘‘final state’’ of industrial wastewater, Cu, Ni, Zn, Fe and other heavy metals in the wastewater are transferred to the sludge. Therefore, the potential environmental hazard of electroplating sludge is much greater than that of industrial wastewater.2,3 Copper sludge will greatly damage the ecological environment if no prevention measures are taken. In addition, the copper, nickel and zinc grades in the electroplating sludge are much higher than those of rich ore. The valuable metals in electroplating sludge have a potential value of more than 50 billion US dollars every year.4 At present, there are many studies that have addressed the comprehensive treatment of electroplating sludge.5–8 De Souza examined the extraction
and recovery of chromium from wastes (class I dangerous) generated by a galvanic manufacturer. The results showed that a 92% recovery of metallurgical grade chromium was possible using the oxidative process for 40 min, at 60C and 1.4 mol/L hydrogen peroxide; after this point, the sludge could be characterized as no longer dangerous.9 Xu
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