Experimental study on precipitating supernatant of rare earth mother liquor by nanofiltration

The supernatant of rare earth mother solution obtained from the leaching of a rare earth company in Ganzhou is treated by the supernatant after NH₄HCO₃ removal of impurity. The concentration efficiency of rare earth ions in the raw liquid by nanofiltration and the separation and recovery of NH₃-N are mainly studied, so as to provide reference for industrial application. The experimental results showed that when the concentration of rare earth ions in the raw liquor was 142.9 mg/L and the concentration of ammonia nitrogen was 346.1 mg/L, the retention rate of rare earth ions in the concentrated liquid side reached 95 % when the operation pressure was 0.8 MPa, the influent pH was 6.49, and the running temperature was 25 degrees. The intercepting rate of impurity ions, such as Ca²⁺, Mg²⁺, Mn²⁺ and Zn²⁺, can reach 75 %~90 %. The ammonia nitrogen through the liquid side is about 60 % of the original concentration. When the supernatant of the rare earth mother solution of 6.0 L is concentrated to 0.6 L, the concentration of RE³⁺ is increased to 1 242.0 mg/L, and the concentration is nearly 8.69 times.