Scheelite is a troublesome raw material in tungsten smelting. After the popularization of alkaline pressure leaching technology in the last century, the smelting capacity and scale of scheelite have been greatly improved, and the technology and process have been further mature. Due to the use of excessive alkali process, although a large part of alkali is consumed in the leaching process, the amount of residual alkali in the crude sodium tungstate solution is still very high after the reaction.

Tungsten oxide is a kind of transition metal oxide, which belongs to n-type semiconductor. At present, a large number of researches have found that w-based oxides not only act as catalytic, electrochromic, solar energy absorbing and invisible materials, but also have the characteristics of semiconductor functional materials such as heat sensitive, pressure-sensitive and gas sensitive.

In recent years, with the development of industrialization and the rapid improvement of people's living standards, environmental pollution has become the main problem facing human beings, especially water pollution, which has attracted more and more attention. Industrial waste water accounts for a large part of the water pollution sources. Because of its dark color and strong toxicity, it is difficult to treat.

To produce tungsten powder from ammonium paratungstate, it is usually necessary to first burn tungsten oxide in a weak reducing atmosphere, and then carry out hydrogen reduction to produce tungsten powder. Most of the tungsten powders prepared by this process are very regular polycrystalline, which are the main raw materials for the preparation of tungsten alloy and tungsten carbide.

Violet tungsten oxide with good reducibility and high hydrogen reduction rate is used to prepare ultrafine tungsten powder, so as to obtain high-quality tungsten carbide powder. Carbonization is an extremely important procedure in the preparation process.

With high chemical activity and hydrogen reduction rate, violet tungsten oxide has become a significant raw material for preparing tungsten carbide powder. High-quality tungsten carbide powder is usually prepared by carbonization of ultra-fine tungsten powder, which is obtained from violet tungsten oxide.

Violet tungsten powder with unique needle structure and high chemical activity is an important raw material for the preparation of ultrafine tungsten powder. The preparation process with violet tungsten oxide is usually fast.

Violet tungsten oxide is suitable for the preparation of tungsten powder with small granularity and good properties, so as to make high-quality cemented carbide. It has high chemical activity and high rate of hydrogen reduction.

In order to extract tungsten from tungsten minerals, at present, China's tungsten metallurgy industry mostly adopts the alkaline smelting system. After high-pressure leaching of sodium tungstate solution, ion exchange is carried out and apt is extracted by evaporation crystallization. At present, there are two outstanding problems in this process that have not been effectively solved: first, the wastewater discharge is large. Second, the discharge of waste salt is large.

How to efficiently prepare w-v-cu composite materials is different from other vanadium oxides because of its rapid and sudden phase transition. The temperature of phase transition is 68 ℃, which can change reversibly from monoclinic system to tetragonal system, making its physical properties such as resistivity, optical transmittance and permeability change greatly. This characteristic makes it have a great prospect in intelligent switch, electronic device and photoelectric equipment. The results show that tungsten can effectively reduce the phase transition temperature of vanadium dioxide, and copper can improve the conductivity of vanadium dioxide.