The dissolution behavior of different forms of tungstic acid in hydrogen peroxide

Alkali extraction is the main process for extracting tungsten from wolframite. But it produces hazardous waste residues which are difficult to dispose of. Acid decomposition and hydrogen peroxide dissolving tungstic acid from decomposition residue is a new route for extracting tungsten from wolframite. The new method can resolve problems caused by alkali route. The dissolution behavior of tungstic acid in the hydrogen peroxide solution is very critical for extracting tungsten. In this research, the dissolution behavior of different forms of tungstic acid in hydrogen peroxide is investigated. The results showed that under the conditions of 1 mol/L H2O2, a pH of 2, a reaction time of 30 min, a liquid-solid ratio of 50:1, and a temperature of 60 °C, the dissolution percentage of WO3∙H2O reached 99.9%. Under the conditions of 1 mol/L H2O2, a pH of 3, a reaction time of 30 min, a liquid-solid ratio of 50:1, and a temperature of 60°C, the dissolution percentage of WO3·2H2O reached 100%. Under the conditions of a hydrogen peroxide concentration of 3 mol/L, a pH of 4, a liquid-solid ratio of 50:1, a reaction emperature of 60 °C, and a reaction time of 8 h, the dissolution percentage of WO3·0.33H2O reached 99%. In addition, the doping experiments showed that when the mass fraction of manganese ions was >5%, the dissolution percentage was >99%, indicating that a small quantity of manganese ions had almost no effect on the dissolution of WO3·H2O in hydrogen peroxide solution. However, the dissolution percentage was only 58.1% when the iron mass fraction was 4.1%, revealing that the presence of iron ions significantly inhibited the dissolution percentage of WO3·H2O in hydrogen peroxide.