High Efficiency Recovery Model of Tungsten Waste

At present, the method of extracting tungsten mostly adopts water immersion method. Before water immersion process, tungsten scrap needs to be sintered. The sintering process directly sinters the mixed powders. During the sintering process, the dust is discharged along with the flue gas, and the valuable metal tungsten is mixed in the dust, which results in the loss of valuable metal tungsten. The unreasonable ratio of raw materials to auxiliary materials leads to the low conversion rate of tungsten when tungsten waste is used to extract tungsten.

In order to solve the problem of low tungsten conversion rate in the existing process, some scholars have provided a process for extracting tungsten from tungsten scrap, including the following steps:

1)Ingredient proportion as raw material: auxiliary material = 45:55. 100 g of tungsten waste, including 50% tungsten-containing catalyst and 50% tungsten-containing grinding material, is made up of 14.5% WO₃, 41.5% SiO₂ and 24.1% Al₂O₃. The rest are phosphorus, arsenic, copper, chromium, cobalt, nickel, fluorine and carbon. According to the stoichiometric calculation of theoretical consumption of WO₃, the addition coefficient of soda is 0.457 by adding 4 times of soda into tungsten scrap, 0.345 by adding 1 times of flake alkali, and 1 by adding 0.05 times of saltpeter.

2)The raw materials and auxiliary materials are mixed in the proportion mentioned above to form a mixture. 5% water is added into the mixture as a binder. After mixing, the mixture is evenly pressed by lotus root coal machine to form a cake prebaking material.

3)After natural drying, the pre-sintered material is placed in the hearth of the heating furnace and sintered at 800 ℃ for 4 hours. After sintering, the cake sintered material is formed.

4)The sintered powder was obtained by crushing the cake sinter. The particle size of the sintered powder was 150 meshes. The sintered powder was added into the water tank for water immersion treatment. The time of water immersion was 25 minutes and the temperature of water immersion was kept at 90 ℃. The purified tungsten compound was extracted by hydrometallurgy. The conversion rate of tungsten was 98.1%.

The raw tungsten scrap can choose any scrap containing tungsten, such as catalyst containing tungsten, scrap containing iron and tungsten or grinding material containing tungsten. Through the proportioning and chemical composition of the raw material, the mixture can be formed well when the proportioning and chemical composition of the raw material are adopted, and the structure strength and high temperature performance of the prebaked material obtained are higher through sintering process and water immersion process. In addition, the purified tungsten compound was extracted during the extraction process, and the content of insoluble tungsten in sinter was reduced. The conversion rate of tungsten was increased, and the conversion rate was over 98%.

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