Resource recovery of scrap De-NOx catalysis

• Main Author: 蕭孟官
• Other Authors: 李清華
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/38120138054751203993

碩士 === 大葉大學 === 環境工程學系碩士班 === 92 === A series of tests of roasting, leaching, solvent extraction, precipitation and crystallization were conducted in this study to recover the valuable metals of tungsten and vanadium from scrap De-NOX Catalysis. The leaching result of this study reveals that 95.6 % of vanadium and 93.6 % of tungsten can be leached from scrap De-NOX Catalysis under the leaching conditions of solid/water=20g/200ml, temperature=70℃, and leaching time=1 hour. After the leaching solution treated by solvent extraction method, 92.2% of total tungsten can be extracted into organic phase under the conditions of 5 vol.% TOA(Tri-octylamine), O/A=1/1, pH=0.5, reducing agent=sodium sulfite (one vanadium equivalent weight) and extraction time=20 minutes. Whereas, 93.5% of total vanadium will remain in the aqueous solution after solvent extraction process. 91.5% of the total tungsten contained in the organic phase can be back-extracted into aqueous solution by using 0.25N NH4OH. This aqueous solution can be further processed by precipitation method with HCl to obtain a product of NH4WO4．3H2O. A final recovery 83.3 % of total tungsten is achieved by using aforementioned processes. For the vanadium contained in the aqueous solution after solvent extraction, it can be recovered by using crystallization process with NH4Cl to obtain a product of NH4VO3. The final recovery of total vanadium by using aforementioned processes is about 93.5 %.