废稀土抛光粉盐酸浸出过程研究

Hydrochloric Acid Leaching Process of Rare Earth Polishing Powder Waste

采用盐酸直接浸出方式从稀土废抛光粉中回收稀土,考察了盐酸浓度、浸出温度、浸出时间和液固比对稀土和主要杂质元素Al_(2)O_(3)浸出率的影响,并探讨了浸出机理。结果表明,HCl体系单级浸出的优化条件为:HCl浓度8 mol/L、浸出温度80℃、浸出时间3 h、液固比4∶1,此时稀土元素浸出率为90.81%,Al_(2)O_(3)浸出率为43.68%。对比了单级浸出、二级浸出和三级逆流浸出效果,证实三级逆流浸出时稀土浸出率高达98.38%,浸出液中稀土总量增加,有利于稀土元素的下一步萃取回收,大大降低了回收成本。

A hydrochloric acid leaching process was adopted to recover rare earth from rare earth polishing powder waste.The effects of hydrochloric acid concentration,leaching temperature,leaching time and liquid⁃solid ratio on the leaching rates of rare earth and main impurity Al_(2)O_(3) were investigated,and the leaching mechanism was also discussed.It is found that the optimal conditions for single⁃stage leaching with HCl system are as follows:HCl concentration of 8 mol/L,leaching temperature of 80℃,leaching time of 3 h,and liquid⁃solid ratio of 4∶1.Under such conditions,the leaching rates of rare earth and Al_(2)O_(3) are 90.81%and 43.68%,respectively.Based on the comparison of results from single⁃stage leaching,two⁃stage leaching and three⁃stage countercurrent leaching,it is shown that the leaching rate of rare earth by three⁃stage countercurrent leaching can be up to 98.38%.An increased amount of rare earth in the leaching solution is beneficial to the extraction and recovery of rare earth elements in the next step,thus greatly cutting recovery cost.