Ammonium Paratungstate Recovery from Soft Waste Containing Tungsten

The tungsten-containing soft waste referred to in the recovery and treatment of tungsten wastes is a kind of soft waste such as leaching residue in the production process of ammonium metatungstate (AMT), ammonium paratungstate flooring material and yellow tungsten flooring material, air pipe material, ammonium paratungstate evaporation mother liquor produced in the production process of tungsten oxide. Inevitably, tungsten still exists in these tungsten-containing wastes. It can be recycled.

ammonium paratungstate recovery from soft waste containing tungsten image

Recently, a new method is needed to overcome the shortcomings of traditional thinking mode and process route, shorten process flow, improve tungsten recovery rate, reduce production cost and prevent environmental pollution. For example, some scholars have proposed the following methods.

The tungsten-containing soft wastes produced in the process of Tungsten Hydrometallurgy are directly mixed with dilute ammonia water and reacted in a sealed way at a set temperature and pressure to convert them into ammonium tungstate solution. Ammonium paratungstate products are obtained by filtration, evaporation and crystallization, solid-liquid separation.

A.Pressurized ammonia leaching: After mixing tungsten-containing soft waste and dilute ammonia water in the process of tungsten hydrometallurgy, the leaching reaction lasts for 1-3 hours at temperatures of 0.2-0.6 Mpa and 120-200 ℃. The molar ratio of dilute ammonia water to NH3 and tungsten in tungsten-containing soft waste is 2.5-4.5:1.

B.Filtration and slag removal: The leaching reaction material after process A is fed into the screening program, and the slag removal is filtered.

C. Crystallization and Separation: The filtrate obtained from process B is fed into the evaporator, evaporated and concentrated at 50-100 ℃ until the density of mother liquor in the slurry is 1.02-1.10 g/ml. Finally, ammonium Paratungstate Crystal is obtained by solid-liquid separation.

The soft waste containing tungsten is leaching slag produced in the production of ammonium metatungstate (AMT), surface material and air pipe material of ammonium paratungstate and yellow tungsten produced in the production of tungsten oxide, evaporation mother liquor or or its mixture in the production of ammonium paratungstate. The concentration of dilute ammonia water is 4-15 wt%.

Ammonium paratungstate crystals are obtained by direct pressure leaching of tungsten-containing soft wastes with dilute ammonia water and regular filtration, evaporation, crystallization and separation. Therefore, it has the advantages of short process flow, low equipment investment, high productivity and high yield, zero emission and no pollution, and the cost of recovery and treatment is only 30-40% of the traditional technology.

 

 

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