Process and device for alkaline extraction and recovery from waste catalysts in SCR (selective catalytic reduction) denitrification

Abstract

The invention discloses a process and a device for alkaline extraction and recovery from waste catalysts in SCR (selective catalytic reduction) denitrification. By adoption of NaOH solution, tungsten and vanadium in the waste catalysts in SCR denitrification are leached into leach liquid while titanium is remained in leach residues, so that separation of titanium from tungsten and vanadium is realized; then an alkaline extraction process is adopted for separating tungsten and vanadium in the leach liquid; finally, a refining process including steps of crystallizing, dewatering, drying and the like is carried out to obtain high-purity ammonium paratungstate and ammonium metavanadate in accordance with national standards, and by-product titanium-rich residues are obtained at the same time. By the process and the device for alkaline extraction and recovery from the waste catalysts in SCR denitrification, valuable metals in the waste catalysts in SCR denitrification can be recovered, and the high-purity ammonium paratungstate and ammonium metavanadate in accordance with the national standards are obtained while the by-product titanium-rich residues are obtained as well.

Description

technical field [0001] The invention belongs to the technical field of industrial solid waste treatment, and relates to a recycling treatment technology of spent SCR denitrification catalysts, in particular to a device and process for alkaline extraction and recovery of valuable metals from SCR denitrification waste catalysts. Background technique [0002] Selective Catalytic Reduction (SCR) is currently the mainstream technology for flue gas denitrification in thermal power plants, and it is currently the most efficient, most mature and most widely used denitrification technology. The technology is widely used in TiO 2 as the carrier, with WO 3 , V 2 o 5 Catalysts with active ingredients such as rare metal oxides. [0003] After several years of use, the activity of the SCR denitrification catalyst drops to a certain level, which cannot meet the requirements of SCR denitrification, so it must be regenerated or replaced. Regeneration can prolong the service life of the ...

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Problems solved by technology

Chinese invention patent applications CN104384167A and CN104772318A both disclose a method for recovering spent SCR denitrification catalysts in which vanadium is first extracted by acid leaching, and then tungsten and vanadium are extracted step by step by alkali leaching. This method not only consumes a lot of acid and alkali reagents, but also low leaching rate

Chinese invention patent applications CN103160690B and CN103484678A all disclose a method for recovering spent SCR denitrification catalysts that first extract tungsten and vanadium by alkaline leaching, and then use ammonium salt and concentrated acid to precipitate ammonium metavanadate and tungstic acid from the leaching solution respectively. Not only does it consume a lot of acid, but also tungsten and vanadium are easy to co-precipitate, resulting in poor separation effect and low product yield

Chinese patent CN104862485A discloses a recovery method of spent SCR denitrification catalyst, which firstly extracts tungsten and vanadium by roasting and leaching, and then extracts tungsten from the leachate by acidic extraction. The effect is poor, and the leaching solution is alkaline, and a large amount of acid is consumed to adjust the pH value, and a large amount of waste water is generated by acid-base neutralization

[0009] 1. High consumption of acid and alkali reagents and low leaching rate;

[0010] 2. The separation efficiency of tungsten and vanadium is low, the impurity removal effect is poor, and acid-base neutralization produces a large amount of waste water;

[0011] 3. Na 2 CO 3 Sintering + water immersion consumes high energy, produces sintering waste gas, alkali is difficult to reuse, and the concentration of tungsten and vanadium in the leaching solution is low;

[0012] 4. The recovery and purification of the three valuable metals of tungsten, vanadium and titanium cannot be realized at the same time

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