How to recycle ammonium tungstate from ammonium paratungstate crystallization mother liquor? The researchers proposed a process for recycling ammonium tungstate from ammonium paratungstate crystallization mother liquor. The purity of ammonium tungstate obtained by this method is high, and the production cost is effectively reduced.
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A Process of Recycling Ammonium Tungstate from Ammonium Paratungstate Crystallization Mother Liquor
Step One: Add 1.7kg of the theoretical amount of 300% phosphoric acid to the ammonium paratungstate crystallization mother liquor (WO3: 30g/L), stir it evenly and place it for 30min, add hydrochloric acid under stirring to make pH=0.5, to obtain ammonium dodecahydrate precipitation, set aside for 16h;
Step Two: Add 32.7L of ammonia with a concentration of 10% to the dissolution tank, heat to 50°C, add the ammonium dodecahydrate precipitation obtained in Step One under stirring (add 10.2L of water to make a slurry), and control the reaction temperature at 65°C, make the precipitation dissolved in ammonium solution, the specific gravity of ammonium tungstate solution is 1.35g/L, and amount of ammonia added should be such that the free ammonia in the ammonium tungstate solution after ammonia dissolution is 25g/L;
Step Three: Add 1.33kg magnesium chloride to the solution prepared in Step Two to generate magnesium phosphate precipitate, filter the precipitate, wherein, the amount of magnesium chloride added should make the magnesium content in the filtrate 0.35g/L; the filtrate obtained in the dephosphorization step enters the D751 resin for adsorption, the height-to-diameter ratio of the D751 resin is 3:1, the flow rate is 5cm/min, until the black T indicates no color change, the resin adsorption is stopped, the solution enters the tungsten removal tank to remove tungsten, and the ammonium tungstate solution is recycled.
