W-Sn Ore Wet Method Producing Ammonium Paratungstate
In recent years, more and more tungsten – tin (W-Sn) ore has been output, however this ore is difficult to separate and enrich by the common methods of gravity, flotation and magnetic separation. An invention has proposed a way to convert tungsten and tin into soluble structure, then change them into solution by controlling different conditions, and finally get both of them respectively into ammonium paratungstate and tin dioxide.
The steps of wet method preparing ammonium paratungstate (APT) from W-Sn ore are like follows:
1. Take the W-Sn ore as raw material, after grinding, acid decompose the ore with strong oxidizing acid nitric acid as acidolysis convert agent of tungsten to get tungsten tin slag mixed;
2. Generate ammonium tungstate solution after dissolving tungstic acid with ammonia water, and filter out the tin slag;
3. Purify the ammonium tungstate solution by ion exchange with macroreticular alkali gel resin, then take the ammonia water and ammonia chloride as desorption agent in the product purification process, while in the mother liquor recovery, the sodium hydroxide is used as desorption agent;
4. Generate the high purity APT by concentration, crystallization and drying the purified liquid;
5. Tin is eventually recovered in the form of tin dioxide by leaching, precipitation, drying from tin slag.