Dissolution Behavior of Sodium Phosphate in a Na3PO4–Na2WO4–NaOH Solution System

Sodium hydroxide autoclaving is the main method for smelting scheelite in China. In this method, sodium phosphate added as an additive to realize highly efficient decomposition of scheelite, and a crude tungstate solution containing obtained. subsequent process ion exchange, phosphorus ions compete with resin adsorption tungstate, which reduces capacity endangers purity solution. To remove from solution, chemical purification usually adopted. The principle use reagents react impurities form precipitates achieve purpose impurity removal. Because advantages simple industrial implementation high removal efficiency, it has been widely used However, some disadvantages. First, additional cost required, other metal would be introduced Second, removed by precipitation sedimented forms but phosphate, makes resource unable recycled tungsten smelting. Therefore, novel needs developed. dissolution behavior Na3PO4–Na2WO4–NaOH system was investigated paper. results showed that binary or ternary systems hydroxide, common-ion effect salt exist simultaneously. decreases solubility while increases phosphate. Increasing concentration lowering temperature can greatly reduce making meet requirements exchange. study lay theoretical foundation development new methods.