Recover Tungsten, Vanadium, Titanium from Waste SCR Catalyst 2/2

3. Add hydrochloric acid into leaching slag
Wash the precipitation obtained in step 2 and adjust pH by adding hydrochloric acid, separated to get s HVO₃ filtrate and residue containing H₂WO₄;
4. Preparation of ammonium Paratungstate
The residue containing H₂WO₄ that obtained in step 3 is joined ammonia with concentrate of 25~30% at 70~80℃ for dissolving, filtering and evaporating to generate ammonium paratungstate crystal;
5. Preparation of ammonium metavanadate
Add ammonia into the filtrate containing HVO₃ which is obtained in step 3, stripping; the stripping liquor goes through filtration, crystallization to obtain ammonium metavanadate, and the raffinate is flowing into reuse process of wastewater.
6. Reuse process of wastewater

The advantages analyzed as follows:
1. The purity and rate of recovery are very high. Ammonium paratungstate and ammonium metavanadate that recycled can be directly used in the production process of SCR catalyst, and the Rutile Titanium Dioxide is high quality raw materials for high-grade ceramic pigment;
2. Zero discharge of industrial waste water;
3. The by-products can be directly soled as product sales to the users downstream;
4. Valuable metals achieve the goal of regeneration and separation and realize harmless clean production;
5. The tall gas generated in the calcination process doesn’t exist by Spray absorption;
6. Use high-pressure water for washing in the pretreatment and the filter reused, which avoid poisonous compounds such as mercury, arsenic, phosphorus and so on in waste SCR catalyst not to be loss with the ash.

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