Leaching process of weathered crust elution-deposited rare earth ore based on direct reuse of oxalic acid precipitated rare earth mother liquor
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(Mo∶Mr)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 0.002 5 mol/L,which is lower than 0.006 3 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 condi-tions.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.
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