Kinetics of alumina extraction from coal gangue by hydrochloric acid leaching
(1. College of Chemical Engineering, Inner Mongolia University of Technology, Hohhot 010051, China;
2. National and Local Joint Engineering Research Center for High Value Utilization of Coal-based Solid Waste, Hohhot 010051, China;
3. Key Laboratory of Ecological Metallurgy of Multi-metal Intergrown Ores of Ministry of Education, Special Metallurgy and Process Engineering Institute, Northeastern University, Shenyang 110819, China)
2. National and Local Joint Engineering Research Center for High Value Utilization of Coal-based Solid Waste, Hohhot 010051, China;
3. Key Laboratory of Ecological Metallurgy of Multi-metal Intergrown Ores of Ministry of Education, Special Metallurgy and Process Engineering Institute, Northeastern University, Shenyang 110819, China)
Abstract: The leaching kinetics of alumina extraction from coal gangue with hydrochloric acid was investigated. The effects of calcination activation temperature and leaching conditions on the alumina extraction efficiency were studied. The results revealed that the alumina extraction efficiency can reach 91.56% under the following optimum conditions: a calcination temperature of 700 °C, dissolution at 150 °C for 2 h in hydrochloric acid with a concentration of 20%, and a liquid-to-solid ratio of 3:1. Notably, lithium was leached simultaneously with alumina, and its leaching rate reached 80.00 %. The leaching of alumina followed the shrinking unreacted core model, and the process was controlled by a chemical reaction, with activation energy of 45.64 kJ/mol.
Key words: coal gangue; acid leaching; calcination activation; leaching kinetics; alumina