Ammonia at Room Temperature Dissolved Ammonium Paratungstate Recycle

Tungsten in the smelting production process will produce ammonium paratungstate waste, tungsten oxide waste, and tungsten powder, tungsten carbide and tungsten carbide scrap and other substandard products.

tungsten hydride reduction image

Some scholars have proposed a solution of ammonium paratungstate or tungsten oxide dissolved in ammonia at room temperature and pressure. The method comprises: mixing ammonium paratungstate (or tungsten oxide) with aqueous ammonia to obtain a mixture; and stirring and raising the temperature of the resulting mixture to obtain a solution containing ammonium tungstate. At present, some manufacturers in order to reduce costs and improve the recycle rate of tungsten smelting, the recycle of substandard ammonium paratungstate as seeds continued to reflow, although you can dispose of substandard products without increasing costs, the doping products used in the production of tungsten powder, tungsten carbide and tungsten carbide will affect the quality of the subsequent products. Some manufacturers also use strong alkali to dissolve unqualified products directly, turning it into sodium tungstate solution to produce ammonium paratungstate, but the cost of this method is very high.

The ammonia solution of ammonium paratungstate reaction equation is:


The ammonia dissolved tungsten oxide reaction equation is:


Put 100g of ammonium paratungstate cleansing solution and 120mL of 25% aqueous ammonia, 150mL of purified water in a sealed reactor at 400rpm mixed stirring speed, heated to 100 degrees Celsius and incubated for 3 hours. The reaction was completed, filtered and cooled to give 265mL ammonium tungstate solution, all clear tank dissolved, the dissolution rate was 100%.

This low temperature and low pressure ammonia solution of ammonium paratungstate and tungsten oxide completely dissolved, adaptable, not only to deal with ammonium paratungstate and tungsten oxide waste, but also can be processed after oxidation of tungsten powder, tungsten carbide and tungsten carbide production waste, the finished product ensured the quality and controlled the cost.