Optimization of Ammonium Tungstate Solution by Ion Exchange Method

Ion exchange method is currently China's tungsten smelting main purification process. At present, strong alkali anion resin 201 x 7 and weak alkaline anion resin are mainly used in the ion exchange process of removing impurity and transforming the tungsten solution.

Using the classical process of anion resin 201 * 7: dilute sodium tungstate solution adsorption and leaching high concentration NH4Cl solution by desorption of ammonium tungstate, but 201 * 7 resin cannot handle APT crystal liquor directly, with alkali heating into salt, high treatment cost; the weak alkaline anion exchange resin is mainly used for the recycle of APT crystallization mother liquor, the general impurity removal efficiency is low, the recycle product is sodium tungstate solution, and the adsorption rate is slow.

In view of the shortcomings of the above two resins in removing impurity and transformation in tungsten containing solution, a new optimization scheme of ion exchange process for ammonium tungstate solution is proposed based on the existing ionic technology. The treatment of sodium tungstate solution or APT crystal mother solution with large pore alkaline anion exchange resin ion exchange treatment can effectively remove impurities and guarantee the quality of ammonium tungstate solution.

Through the sodium tungstate solution or APT crystallization mother liquor with macroporous weakly basic anion resin, with ammonia and ammonium salt, with quick after the speed of desorption method, the tungsten was quickly desorbed, and can maintain a certain degree of desorption of free ammonia , to ensure that high concentrations of qualified ammonium tungstate solution to prevent or reduce the precipitation of crystals. By controlling the pH value of the solution after acidification, the impurities in the tungsten containing solution are difficult or few to form a heteropoly acid root that can be adsorbed by the resin, thus achieving the purpose of removing impurities. For the raw materials of tungsten and molybdenum in the mass ratio of W: Mo < 5000, adding Na2S solution, and meet the requirements of removing molybdenum. The ammonium salt is added as an additive to further inhibit the precipitation of the crystal.

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