钕铁硼废料熔分渣盐酸浸出稀土的实验研究

Experimental Study on Hydrochloric Acid Leaching of Rare Earth from Melting Separation Slag of NdFeB Waste

以钕铁硼废料经H_(2)选择性还原-渣金熔分处理得到的多组元熔分渣为原料进行盐酸浸出,研究了低温常压和高温高压条件下各因素对稀土浸出率的影响,并对浸出过程的动力学进行了分析。实验结果表明:低温常压浸出最优条件为盐酸浓度2.84 mol/L、液固比10∶1、时间60 min和温度85℃,稀土浸出率达到96.04%;浸出过程受扩散和化学反应混合控制,表观活化能29.25 kJ/mol,指前因子2.0209 s^(-1),与盐酸浓度和粒度相关的反应级数分别为1.49和-0.55。高温高压浸出最优条件为盐酸浓度2.03 mol/L、液固比10∶1、时间30 min和温度110℃,稀土浸出率达到98.13%;回收得到的稀土氧化物主要为Pr_(4)O_(7)和Nd_(2)O_(3),纯度达99.56%;浸出过程属于内扩散控制,表观活化能为9.63 kJ/mol,指前因子为3.57×10^(-3) s^(-1)。

Multicomponent melting separation slag,obtained from NdFeB waste by H_(2) selective reduction and melting separation,was used as raw material for hydrochloric acid leaching.The influence of reaction factors on the leaching rate of rare earth under the conditions of low temperature and atmospheric pressure and high temperature and high pressure was investigated.And the kinetics of the leaching process was also analyzed.The experimental results show that the optimal leaching conditions at low temperature and atmospheric pressure are hydrochloric acid concentration of 2.84 mol/L,liquid-solid ratio of 10∶1,time of 60 minutes and temperature of 85℃,and the leaching rate of rare earth reaches 96.04%.The leaching process is controlled by a mixture of diffusion and chemical reactions,with an apparent activation energy of 29.25 kJ/mol,a preexponential factor of 2.0209 s^(-1),and reaction orders related to the hydrochloric acid concentration and particle size of 1.49 and-0.55,respectively.The optimal leaching conditions at high temperature and high pressure are hydrochloric acid concentration of 2.03 mol/L,liquid-solid ratio of 10∶1,time of 30 min and temperature of 110℃,and the leaching rate of rare earth reaches 98.13%.The reco-vered rare earth oxides mainly contain Pr4O7 and Nd_(2)O_(3) with a purity of 99.56%.The leaching process is controlled by internal diffusion,with an apparent activation energy of 9.63 kJ/mol and a preexponential factor of 3.57×10^(-3)s^(-1).