Deep Purification Technology of Aluminum Electrolysis Flotation Carbon Slag Based on Atmospheric Acid Leaching
Received:September 27, 2022   Revised:October 03, 2022   Accepted:October 08, 2022      Published Online:January 09, 2023
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DOI:doi:10.3969/j.issn.1007-7545.2023.02.009
KeyWord:aluminum electrolysis; flotation carbon residue; atmospheric acid leaching; recycled carbon materials
                    
AuthorInstitution
LI Xiao-qing 贵州师范大学材料与建筑工程学院
HE Liu 贵州师范大学材料与建筑工程学院
WANG Xuan 贵州师范大学材料与建筑工程学院
ZHOU Jun 贵州师范大学材料与建筑工程学院;贵州省铝电解炭素材料工程技术研究中心
PENG Qian 贵州师范大学材料与建筑工程学院;贵州省铝电解炭素材料工程技术研究中心
YAO Zhen 贵州师范大学材料与建筑工程学院
LIU Wei 贵州师范大学材料与建筑工程学院;贵州省铝电解炭素材料工程技术研究中心
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Abstract:
      Aluminum electrolysis carbon slag is a dangerous solid waste continuously produced and inevitable in aluminum electrolysis industry. At present, carbon slag is mainly treated by flotation process. However, due to the low carbon content of flotation carbon slag and the risk of secondary pollution, the prospect of its resource utilization is limited. Effects of HCl concentration, acid leaching temperature, L/S, stirring rate and leaching time on treatment effect were studied by atmospheric pressure acid leaching depth purification. XRD, XRF, leaching toxicity analysis were used to explore the changes of phase composition, element content, leaching toxicity before and after treatment of carbon slag. The results show that carbon content of leached slag rises first and then slows down with the increase of hydrochloric acid concentration, acid leaching temperature, L/S, stirring rate, and acid leaching time. Carbon content of carbon slag rises from 82.67% to 98.05% and fluorine leaching concentration drops from 137.8 mg/L to 62.49 mg/L under the optimum conditions including HCl concentration of 4 mol/L, acid leaching temperature of 60 ℃, stirring rate of 1 200 r/min, L/S=25, and leaching time of 4 h. The atmospheric acid leaching process has technical feasibility to realize deep purification of flotation carbon slag.
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