Ammonium Paratungstate Prepared from Tungsten Scraps

With tungsten massive mining and use level increasing, tungsten resources will be less and less, and the world tungsten industry will face a severe situation. Reasonable recovery of tungsten scraps can make up for the shortage of tungsten resources, which brings huge economic benefits. A method which will bring good economic benefit and promote the tungsten scraps recycling by the time preparing ammonium paratungstate (APT).



The specific preparation steps are:
1. Electric solution and magnetic separation: tungsten scraps separated in electrolyte solution to obtain tungsten carbide pellets, and then separator;
2. Decarburization: tungsten carbide set in the furnace for decarburization reaction to get tungsten oxide, control the temperature in 500~1600℃, keep the air circulation or inlet 0.5 ~ 1.0atm oxygen;
3. Dissolved in alkali solution: add tungsten oxide into NaOH solution which the mass concentration is 30%~50%, control the temperature at 130~180℃, stirred and soaked to obtain crude sodium tungstate;
4. Impurities removal: filter the sediment to remove bivalent ions of cobalt, nickel, iron and manganese, and also other impurities.
5. Dissolved in ammonia solution, and then crystallize: adding and stirring ammonia into tungsten organic phase, and then crystallize to obtain high purity ammonium paratungstate.

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