Method for recycling tungsten and vanadium from waste SCR denitration catalyst

Abstract

The invention provides a method for recycling tungsten and vanadium from a waste SCR denitration catalyst. The method includes the steps that firstly, tungsten and vanadium are leached out, wherein the waste SCR denitration catalyst is placed into a NaOH solution to be leached out, and by means of solid and liquid separation, alkaline leaching liquid containing tungsten and vanadium and residues TiO2 are obtained; secondly, tungsten and vanadium in the alkaline leaching liquid are extracted and purified, wherein a kerosene solution containing primary amine N1923 serves as an extracting agent for extraction; and thirdly, reextraction separating and recycling of tungsten and vanadium in an extracted organic phase are performed. According to a process for extracting tungsten and vanadium fromthe waste SCR denitration catalyst in an alkaline leaching manner, due to the fact that waste catalyst powder and the NaOH solution are subjected to one time of leaching in a high pressure state, a liquid phase containing Na2WO4 and Na2VO3 can be obtained, efficient leaching of tungsten and vanadium is achieved, the W leaching rate reaches 97.46%, the V leaching rate reaches 88.6%, it is also kept that crystalline grains of TiO2 are anatase, and anatase can be reused as a catalyst carrier.

Description

technical field [0001] The invention belongs to the field of catalyst regeneration, and in particular relates to a method for recovering metal-containing catalysts. Background technique [0002] With the rapid development of industry, environmental damage such as smog and acid rain caused by automobile exhaust and industrial exhaust pollution has attracted more and more attention. Toxic nitrogen compounds (NO), sulfur compounds (SO2), and hydrocarbons (HC), their direct emissions are the main causes of acid rain, photochemical smog, and ozone depletion. In order to effectively treat nitrogen oxides and other toxic substances in various exhaust gases, it is necessary to denitrify the exhaust gas, and use a denitrification catalyst to convert nitrogen oxides into nitrogen and water. At present, the most widely used exhaust gas purification treatment is selective catalytic reduction (SCR) denitrification technology, and V 2 o 5 -WO 3 / TiO 2 Catalysts have gradually become ...

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Problems solved by technology

Typical ones are: Patent CN201410534406.8 discloses a method for recovering tungsten, vanadium, and titanium in spent SCR denitration catalysts, wherein metal vanadium and tungsten are leached by grinding the catalyst into a powder with a particle size of less than 150 μm, and mixing it with carbonic acid The sodium powder is stirred evenly, then roasted at high temperature, and then the roasted product is placed in hot water for vanadium and tungsten leaching; the method in the patent CN201010254247 roasts the catalyst twice, and then uses hot water to extract vanadium and tungsten. The leaching, tungsten and vanadium leaching rate is less than 90% and other insufficient characteristics

[0004] Patent CN105274341 uses a comprehensive method of roasting and leaching for spent SCR catalysts, and patent CN201410534406.8 uses hot water to leach tungsten and vanadium from solid waste SCR denitrification catalysts. Although the leaching efficiency is high, toxic gases such as SO 2 gas etc.

The metal recovery method reported in the above-mentioned patents generally adopts the roasting method, the process flow is complicated, and it will produce toxic gas to pollute the environment. In addition, almost all the researches on the recycling of spent catalysts only focus on the effective extraction of valuable metals, and there is no work While extracting metals from waste, we also pay attention to the recycling of the remaining spent catalyst after leaching. If the remaining leaching slag is discarded, it will cause serious secondary pollution to the environment.

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