Preparation method of phosphotungstic acid

A preparation method of phosphotungstic acid, comprising:

• mixing a mixed solution containing tungsten, phosphorus and an inorganic acid with an organic-alcohol-containing oil phase for extraction, the organic-alcohol-containing oil phase includes an extractant, wherein the extractant is consisting of an organic alcohol, combining an obtained supported organic phase with a stripping agent according to an oil phase:aqueous phase volume ratio of 3:1 to 10:1 to obtain a stripping solution, wherein the stripping agent is consisting of distilled water, and carrying out thermal evaporation crystallization or spray drying on the stripping solution to obtain a phosphotungstic acid crystal;
• comprising Scheme A, Scheme B, Scheme C or Scheme D:
• Scheme A:
• the mixed solution is obtained by reacting a tungsten source of white tungstic acid or artificial scheelite with an aqueous solution of a phosphorus compound and the inorganic acid;
• Scheme B:
• the mixed solution is obtained by dissolving an industrial sodium tungstate crystal in water, then adding the phosphorus compound and the inorganic acid and mixing;
• in the extraction process in Scheme A and Scheme B, the oil phase:aqueous phase volume ratio is 2:1 to 1:5;
• Scheme C:
• the mixed solution is a phosphotungstic acid solution containing the inorganic acid, which is obtained by dissolving an industrial phosphotungstic acid crystal in water, adding the inorganic acid and mixing, wherein the concentration of tungsten trioxide is 50 to 150 g/L, and the volumetric molar concentration of the inorganic acid is 0.5 to 6 mol/L;
• in the extraction process, the volume concentration of the organic alcohol in the organic-alcohol-containing oil phase is 5 to 50%;
• the oil phase:aqueous phase volume ratio is 1:1 to 10:1;
• and
• Scheme D:
• the mixed solution is a tungsten-containing sulfuric acid-phosphoric acid mixture solution;
• wherein the concentration of tungsten trioxide is 25 to 150 g/L, the concentration of phosphoric acid is 10 to 200 g/L, and the concentration of sulfuric acid is adjusted to 1.5 to 2.5 mol/L;
• and the oil phase:aqueous phase volume ratio in the extraction process is 3:1 to 1:3.