Preparation of high purity ammonium rhenate from the solution after precipitation of tungsten and molybdenum

Abstract:

Potassium rhenate was obtained from the solution after precipitation of tungsten and molybdenum by potassium chloride precipitation reaction. Then potassium rhenate solution was converted into perrhenic acid solution by ion exchange method. Finally, high purity ammonium rhenate was obtained by ammonia neutralization - concentrated crystallization - recrystallization. The results show that KCl solid is added to the solution after precipitation of W and Mo, and then concentrated to precipitate KReO₄ white crystal. The contents of main impurities Na, Ca, Fe and Cl in potassium rhenate are less than 1%, especially W and Mo are less than 0.1%, and the crystallization rate of Re can reach 94% ~ 98%. K is removed by dynamic method with C160 (H^₊ type) resin. When the pH of KReO₄ solution is neutral and the flow rate of feed is 2 BVs.h^_-, the K ^₊ penetration capacity and saturation capacity of C160 resin are 117.865 g.L^_-1 and 128.385 g.L^_-1, respectively, and the utilization rate of resin reaches 91.81%. The concentrations of K, Na, Ca, Fe, W, Mo and Mg in the obtained pure HReO₄ solution are all below 0.5 mg.L^_-1. The HReO₄ solution is neutralized by adding high - grade pure ammonia, controlling the end-point pH to 7 ~ 8, and then concentrated and crystallized with one recrystallization. The purity of the obtained ammonium rhenate is more than 99.99%, of which the SEM morphology is dendritic.

Key words:Solution after precipitation of tungsten and molybdenum; potassium rhenate; concentrated crystallization; ion exchange; ammonium rhenate