Ammonium paratungstate (APT) and tungsten trioxide scraps, as well as substandard products such as tungsten powder and carbide scraps will produce in the smelting process. At present, there are two main ways to deal with these substandard products:
1. Add unqualified products into tungsten products processing as a crystal seed in order to reduce costs and improve the recovery rate of tungsten smelting. Although this process can deal with the substandard products without increasing cost, but it will affect the quality of tungsten powder and carbide;
2. The method that directly dissolve substandard products into alkali to get sodium tungstate solution, and then returned to the production of APT will cost much.



A method that can effectively dissolve APT is proposed in this paper. Mix APT with ammonia, then stir and heat, to effectively get APT reacted with ammonia and generates ammonium tungstate solution.

The specific steps are as follows:
1. Mix APT with ammonia to get the mixture;
2. Make APT dissolved in ammonia, and the tungstate solution;
3. Evaporate and crystallize the tungstate solution to generate APT qualified.

Advantages:
1. recycling tungsten in smelting process at low cost, further improve the recovery rate, reduce energy consumption, and provides a foundation for new technology and product research of tungsten smelting;
2. Shorten the process, increasing the efficiency, and simplify the equipment and operation;
3. Achieve the goal of clean production in tungsten smelting to make tungsten smelting site easier to manage and cleaner.

Photocatalytic also called photocatalyst, it is a kind of light irradiation, it can not afford to change itself, and it can promote chemical reactions, photocatalyst is naturally energy by converted into chemical to act as a catalyst, so that oxygen and water molecules around can excite into highly oxidizing power of the free ions. It can decomposable harmful organic substances and some inorganic substances, not only accelerate the reaction, also cause waste of resources and the formation of additional pollution.

Tungsten TrioxideApplications:
1: Air purification. Tungsten trioxide photocatalyst can use water vapor and oxygen in the air to remove contaminants from the air in the greenhouse, such as nitrogen oxides, sulfur compounds, formaldehyde and other harmful gases. In addition, it can also be used for photocatalytic degradation of industrial waste gas.
2: Anti-fog and self-cleaning. The use of tungsten trioxide to prepare tungsten trioxide thin films has the same photocatalytic action. The respect to the terms of the tungsten trioxide powder has high hydrophilic. Under ultraviolet light strong oxidizing, the power can be generated by the decomposition of organic matter adsorbed on the above-fog and hydrated carbon dioxide that reaches self-cleaning effect.
3: Anti-bacterial. The use of tungsten trioxide photocatalytic photo-generated electrons and photogenerated holes H₂O that adsorbed to the catalyst surface is to form an active superoxide ion with strong oxidizing, and bacterial cells or components of biochemical reactions within the bacteria, we can completely kill the bacteria, the degradation by bacteria also release toxic compounds, which prevents secondary pollution caused by endotoxin.

A method of using unqualified, waste and dirty ammonium paratungstate (APT) as raw materials to generate high purity APT is presented in this paper.

The method includes steps as following:
1. Calcining materials (unqualified, waste and dirty APT) to obtain tungsten trioxide;
2. Dissolving tungsten trioxide generated in ammonia to form ammonium tungstate solution;
3. Filtering ammonium tungstate solution generated, remove the solid impurities, and then evaporate and crystallize to get wet APT;
4. Drying and screening the wet APT crystal to obtain high purity APT with total content of impurities in less than 65ppm.

Characteristic of this method:
1. Using the general and unqualified APT to produce high purity APT is a purification process;
2. High purity APT will meet the follow-up APT deep processing to the production of high quality tungsten products;
3. Through the method of roasting APT to get tungsten trioxide and then dissolved in ammonia can impactful solve the problem of bed effect on apt direct dissolve in ammonia;
4. Part of impurities that difficult to remove is removed in the APT calcination process, and create the conditions for the production of high purity APT products;
5. Solve the practice that low quality of APT back to the main process by alkali dissolution, and improve the recovery rate of production process, reduces cost, and produce high purity APT products at the same time.