基于草酸沉淀稀土母液直接复用工艺的风化壳淋积型稀土矿浸取

Leaching process of weathered crust elution-deposited rare earth ore based on direct reuse of oxalic acid precipitated rare earth mother liquor

为解决草酸沉淀稀土母液复用浸矿工艺无法在禁止使用强酸强碱的矿区开展这一问题,优化了稀土沉淀工艺以减少母液中残留草酸,探索了母液中草酸对稀土浸出过程的影响,从而实现沉淀母液直接复用浸矿,并对其动力学模型和传质过程进行分析。结果表明:优化工艺条件为草酸与稀土的摩尔比(M_(o)∶M_(r))为3.5,草酸质量分数为5%,搅拌速率为300 r/min,陈化时间为8 h,此时,沉淀母液中残留草酸浓度为0.0025 mol/L,低于0.0063 mol/L,可直接用于稀土浸取过程,稀土浸出率达90%以上,表明优化工艺条件下可实现沉淀母液直接复用;草酸沉淀稀土母液直接复用工艺中稀土的浸出过程受内扩散动力学控制,浸取温度的升高有利于稀土的浸取传质过程。

In order to solve the problem that the reuse leaching process of rare earth(RE)mother liquor precipitated by oxalic acid cannot be carried out in the mining area where strong acid and alkali are prohibited,the rare earth precipitation process was optimized to reduce the residual oxalic acid in the mother liquor,and the effect of oxalic acid in the mother liquor on the rare earth leaching process was explored,so as to realize the direct reuse leaching of the precipitation mother liquor.Then its dynamic model and mass transfer process were analyzed.The results showed that the optimum conditions were as follows:the molar ratio of oxalic acid to rare earth(M_(o)∶M_(r))is 3.5,the mass fraction of oxalic acid is 5%,the stirring speed is 300 r/min and the aging time is 8 h.At this time,the residual oxalic acid concentration in precipitation mother liquor is 0.0025 mol/L,which is lower than 0.0063 mol/L,it can be directly used in the leaching process of rare earth,and the leaching efficiency of rare earth is more than 90%,which indicates that the mother liquor can be directly reused under the optimized process conditions.In the direct reuse process of oxalic acid precipitated rare earth mother liquor,the leaching process of rare earth is con-trolled by internal diffusion kinetics,and the increase of leaching temperature is beneficial to the mass transfer process of rare earth leaching.