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Mo、P、As是工业Na_2WO_4浸出液中的常见杂质,胍盐法能有效地除去。操作时先将含Mo、P、As的Na_2WO_4溶液酸化至Z(H~+/W)=1.14,WO_4~(2-)聚合成仲钨酸A,再在SiO_2催化作用下,加热使仲钨酸A转变成仲钨酸B。此时由于溶液的pH从6.7升高到8.1,以至Mo、P、As以MoO_4~(2-)、HPO_4~(2-)、HAsO_4~(2-)形式存在。然后加入胍盐使仲钨酸B形成胍盐沉淀,杂质留在溶液中。当pH=7.5～8.1时,钨沉淀率96～99％,除钼率95～99％,除磷率82～90％。钨的胍盐沉淀物用NaOH或氨水处理,可分别制得Na_2WO_4和APT,胍几乎定量回收。
Mo, P, As are common impurities in industrial Na_2WO_4 leachate, and the guanidinium salt method can be effectively removed. In the operation, the solution of Na_2WO_4 containing Mo, P, As is first acidified to Z (H ~ + / W) = 1.14, and the WO_4 ~ (2-) is polymerized into the paratungstate A. Under the catalysis of SiO_2, Acid A is converted to paratungstic acid B. In this case, the pH of the solution increased from 6.7 to 8.1, and Mo, P and As were present in the form of MoO 4 2-, HPO 4 2-, and HAsO 4 2-. The guanidinium salt is then added to precipitate para-tungstic acid B to form a guanidinium salt and the impurities remain in solution. When pH = 7.5-8.1, the precipitation rate of tungsten is 96-99%, the removal rate of molybdenum is 95-99% and the removal rate of phosphorus is 82-90%. The tungsten guanidinium salt precipitate was treated with NaOH or ammonia to make Na 2 WO 4 and APT, respectively, and guanidine was almost quantitatively recovered.