Method for extracting vanadium pentoxide from spent catalyst

Abstract

The invention relates to methods for extracting vanadium pentoxide from spent sulfur dioxide oxidation catalysts. The spent vanadium-containing catalysts are processed by leaching with sulfuric acid, and the resulting suspension is treated with an ammonia solution in the presence of hydrogen peroxide to pH 5–5.5 and pH 7.0–8.0. The insoluble precipitate is filtered, dried, and calcined in an oxidizing atmosphere. The precipitate is redissolved in ammonia to form a suspension. Ammonium nitrate is added to the filtrate from the suspension, and the solution is stirred until ammonium vanadate precipitates, then dried and calcined at 550–600°C. This invention enables the maximum recovery of vanadium pentoxide from spent vanadium-containing catalysts, up to 98.5%.