Diatomite Tungstate Filtration Method

At present, the preparation method of tungstate is through calcium tungstate to add inorganic acid to obtain required tungstic acid, then the ammonia will dissolve into the solution of coarse tungsten tungstate, ammonium tungstate. Due to the increase of pH value, acid decomposition process without washing clean iron and manganese and soluble impurities can be hydrolyzed and precipitation, metasilicate H₂SiO₄ insoluble in alkaline medium into slag and no decomposition of mineral particles and removal.

Recently, some scholars have proposed a method for preparing ammonium partrunate. By adding diatomite in the preparation process, diatomite will not affect the purity of ammonium tungstate solution after ammonium tungstate is dissolved, no impurity will be introduced, and the generated tungstic acid will be easy to filter. In addition, diatomite has well-developed pores, which can adsorb fine tungstic acid particles. In the process of ammonia dissolution, diatomite can be precipitated, and it can be recycled after washing. The general flow of the scheme is as follows:

1.The hydrochloric acid solution and diatomite are mixed and heated to get the hydrochloric acid solution containing diatomite.

2.Sodium tungstate solution is added into the hydrochloric acid solution containing diatomite and stirred, and a mixed solution containing tungstic acid is obtained.

3.A mixture of tungstic acid and diatomite is obtained by the first filtration treatment with the mixed solution containing tungstic acid.

4.A mixture of tungstic acid and diatomite and ammonia mixed to give a diatomite containing ammonium tungstate solution;

5.The ammonium tungstate solution containing diatomite was treated by second filtration, and diatomite and ammonium tungstate solution were obtained.

6.The ammonium tungstate solution is evaporated and crystallized to obtain the ammonium parotungstate.

The results showed that tungstic acid generated by adding diatomite in the preparation process was easier to filter, significantly shortened the preparation time of ammonium partrunate, effectively solved the problem of tungsten acid sticky and difficult to filter, and had high recycle rate and less loss of tungsten element.

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