Researchers have proposed a method for producing ammonium paratungstate using tungsten-contained waste material, which has the advantages of short production process. Evaporated and crystallized waste ammonia gas and wastewater can be recycled and reused. And it significantly reduces emissions of waste gas and wastewater. Also, it improves the tungsten recovery rate.
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A Method for Producing Ammonium Paratungstate Using Tungsten-contained Waste Material
Step One: Acid leaching and removing impurities from tungsten-contained waste material (containing metal tungsten or tungsten carbide);
Step Two: The wet tungsten slurry obtained in Step One is solid-liquid separated, washing and purging, and placing in a drying furnace for drying and dewatering treatment, setting the drying temperature and the thickness of the material layer, after drying, it is placed in a kiln for oxidation treatment to oxidize tungsten into tungsten oxide;
Step Three: Put the tungsten oxide into the ammonia solution, heat it, and control the transformation pressure. After the heat preservation and stirring, the crude ammonium tungstate solution is prepared. The trace impurity elements Co, Fe, Ca and other ions are converted into hydroxides and separated by precipitation;
Step Four: According to the residual impurities Cu, Al, Mg, Ti and other metal ions and S2- content of the obtained crude ammonium tungstate solution, adding ammonia sulfide, hydrogen peroxide and other purifying agents, slag precipitation, solid-liquid separation to obtain ammonium tungstate solution;
Step Five: Crystallization and drying of refined ammonium tungstate solution to obtain ammonium paratungstate.
