Tungsten Molybdenum Separation from Phosphotungstic Acid / Phosphotungstate solution

Tungsten and molybdenum have the same atomic radius and similar electronic structure, showing very similar chemical properties. Therefore, tungsten and molybdenum are often found in scheelite in nature. Tungsten and molybdenum separation is a technical problem in tungsten smelting process.

In order to clean and efficiently handle complex tungsten and molybdenum resources, Central South University has developed the technology of synergistic decomposition of sulphuric acid and phosphoric acid mixed system. The results show that, no matter the grade of tungsten and molybdenum in the mineral, tungsten and molybdenum can be leached efficiently after the decomposition of the mixed acid system of phosphorous phosphorus. The content of tungsten and molybdenum in the decomposed slag can be reduced to less than 0.5%. The decomposition technology uses a cheaper sulfuric acid and phosphoric acid as the leaching agent. It can completely replace the traditional sodium alkali decomposition process, and the decomposition efficiency is high. At the same time, it can eliminate the environmental problems caused by the discharge of soluble sodium salt.

A method for extracting tungsten from molybdenum phosphotungstic acid / phosphotungstate solution comprises the following steps:

The concentration of WO₃ is 260g/L, the concentration of Mo is 80g/L, the concentration of P₂O₅ is 100g/L, the molar ratio of the phosphotungstic acid with the concentration of 80g/L is 2:1, and the concentration of hydrogen peroxide is 30%. The stirring reaction makes the tungsten form peroxy tungstate and molybdenum forms peroxy molybdate.

SO₂ was used in the mixture to control the mixture temperature of 25°C, the reaction time was 120 minutes, and the solution became colorless. The tungsten was precipitated, filtered, and washed with tungstate form.

The tungstic acid precipitated after washing was dissolved with ammonia to obtain ammonium tungstate solution, and then evaporated and crystallized to obtain APT. After testing, it reached the 0 level of national standard.

The molybdenum solution containing sulfuric acid and phosphoric acid is extracted by solvent extraction to extract molybdenum, the residual liquid is returned to the leaching of tungsten and molybdenum minerals.

Ammonium molybdate solution was obtained by stripping ammonia solution, and four ammonium molybdate was obtained after acid precipitation. The detection reached the national 0 grade standard.

The above method is based on the improvement and innovation of "co decomposition technology of phosphorous phosphorus mixed acid system". The separated tungsten is directly used in the preparation of its products. The separation effect is good, the operation process is simple and easy to control, and it is easy to be popularized and applied in the industrialization.

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