Leaching Kinetics of Calcium and Rare Earth from Weishan Rare Earth Concentrate
At present,the mainstream process of Weishan rare earth concentrate smelting proposed uses oxida-tive roasting-hydrochloric acid leaching-alkali optimal solution method to extract rare earths from minerals.The"three wastes"smelting process of Weishan rare earth concentrate is serious and the production cost is high,which should be improved to meet the national"double carbon"strategy implementation.Using 41.28％rare earth concentrate from Shandong Weishan as raw material,the rare earth was further enriched after using hydro-chloric acid to leach impurity element calcium.By discussing the effects of leaching temperature,initial acidity,acid-to-ore ratio and other conditions on the leaching of calcium and rare earth elements,the leaching condi-tions were optimized as follows:the concentration of HCI is 2 mol·L-1,leaching temperature is 90 ℃,acid-ore ratio is 5 mL·g-1.In the optimization of process conditions,the leaching rate of calcium is 89.4％,and the leaching rate of rare earth is 12.13％.The bastnaesite leaching kinetics of the process was studied.The results show that the concentration of the chemical reaction and diffusion control calcium leaching kinetics equation and the concentration of internal diffusion controlls rare earth leaching kinetics equation.The apparent activity ener-gy of calcium and rare earth leaching was calculated to be 14.0628 and 6.146 kJ·mol-1.
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