| Spent SCR catalyst contains V, W, Ti and other valuable metals. Direct discard will not only cause environmental pollution, but also a waste of natural resources, so the recovery of valuable metals from spent catalyst have great significance. Raises the method of use Na OH solution to leach V and W from spent catalyst. Then precipitated leaching liquid with calcium and use formic acid selective leaching V from calcium formate. Impurity and added with Ammonia, Vanadium will precipitate in the form of ammonium metavanadate. After acid leaching, tungsten in the precipitate is added with Hydrochloric acid, and converted to tungstate. Burning generating tungsten trioxide.The best conditions for Na OH concentration was 25%, the ratio of solid and liquid 1:7, catalyst particle size of 125 ~ 180 microns, the temperature of 60 ?, the leaching time of 60 min.The optimized technological parameter is obtained as follows through experiment: calcinatingtemperature,ratio of sodium carbonate and raw materials weight, calcinatingtime, hot water amount, 5% dilute sulphuric acid, extracting temperature and extracting time, Under the optimization conditions.Best conditions: calcination temperature 700 ?, Na2CO3 and raw material ratio 3.8, roasting time 3.5 h, 80 ? deionized water, 80 ml, stand for 2h after fully mixing, 5% of the 125 mldilute sulphuric acid.This article innovative to scrap the main metal elements in the SCR catalysts Ti, V and W,providing better recycling approaches and high recovery rate, 92.15%, 92.15% and 85.21%, respectively.Process is more clean, present more popular methods, reduce secondary pollution and secondary emissions. Alkaline leaching filtrate and filtration residue in the process of back to V, W and Ti respectively, at the same time in the process of alkali and acid can be secondary recovery.It has certain economic benefits, for waste catalyst recycling and provide theory support and technology reference for industrial application. |
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