Quaternary Ammonium Salt Direct Extraction Method

At present, in the process of producing ammonium tungstate solution by tungsten mine, the technology of separating P, As, Si and Mo from tungsten ore to produce high pure ammonium tungstate solution has the classical chemical method, the current extraction method and the ion exchange method.

In the extraction process, the extraction of quaternary ammonium salt is a new process for the preparation of ammonium tungstate solution from the high pressure leaching solution of tungsten ore soda. The process has removed P, As and Si at the same time, while the separation of Mo is to add NH₄HS in (NH₄) 2WO₄ solution, and the Mo is converted to thiomolybdate, then removed by extraction of quaternary ammonium salt. The method can directly treat the high-pressure leaching solution of tungsten ore soda, and extract the residual liquid back to the leaching solution. It does not consume inorganic acids and it can recover excess soda. This paper describes the direct extraction of tungsten ore in the presence of caustic leaching solution.

The process of extracting tungstate solution by P, As and Si with direct extraction of tungsten is characterized by the use of CO2-3 type quaternary ammonium salt as extractant and a certain polar ameliorant and diluent to form organic phase. The concentration of the extractant is 200 to 400g/l, the organic phase is directly exposed to the sodium leaching solution of tungsten ore to carry out multistage countercurrent extraction. In this process, W is extracted into the organic phase, the impurity P, As and Si are separated from the extractive solution. The loaded organic phase is extracted from the NH₄HCO₃ or NaHCO₃ solution of 1 to 3mol/l by the reverse extraction of the NH₄HCO₃ or NaHCO₃ solution, the pure ammonium tungstate or sodium tungstate solution is obtained. After the stripping, the organic phase is regenerated by the solution of NaOH water and the residual liquid produced in the process. The organic phase regeneration solution is returned to leaching through proper treatment.

One step extraction separation process of ammonium tungstate solution from P, As, Si and Mo is characterized by:

Three ways to adjust the pH of the crude Na₂WO₄ solution, then measure the solid sulfide base into the coarse Na₂WO₄ solution to the pH, control the concentration of free sulfur ions in the solution of 1 to 10g/l, maintain 48 ~ 0.5hr at the temperature of 60~90°C at room temperature, or the crude Na₂WO₄ solution by membrane electrolysis through the H₂S gas at room temperature. At room temperature of 48 ~ 0.5hr at 60~90°C, Mo and As are fully converted into thioate, WO₃ concentration of Na₂WO₄ solution treated by deionized water is adjusted and the solution of pH to 8~9 to WO3 50 ~ 300g/l with 1 ~ 4mol/l NaOH liquid is adjusted.

Multistage countercurrent extraction was carried out with CO2-3 quaternary ammonium salt as extractant and organic phase mixed with certain polarity improver and diluent. In the process, Mo, W and As were extracted into organic phase, and impurities P and Si were separated from the raffinate. Then W and Mo and As were carried out by stepwise reverse extraction. The high purity (NH₄) ₂WO₄ or Na₂WO₄ solution was first extracted with NH₄HCO₃ or NaHCO₃ solution multistage counter current, then the organic phase was oxidized by oxidizing agent, then Mo and As were extracted with bicarbonate solution, or the oxidation and stripping were carried out simultaneously. Finally, the reverse organic phase was regenerated by the NaOH aqueous solution, and the residual liquid produced during the process was produced. The regeneration solution of organic phase can be used for leaching by proper treatment.

Using direct extraction method to treat tungsten ore, the raw materials are widely used, the process is short, the cost of products is reduced, it is easy to realize industrial production.

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