Process for working up vanadium-containing used catalysts

摘要

The process provides: leaching of the vanadium-containing used catalyst in the presence of vanadium(II) ions; separation of the slurry obtained into a solid support which after the treatment is used for the preparation of the vanadium catalyst, and into a solution, a portion of which is passed to electrochemical treatment which is carried out with a cathodic current density of from 100 to 300 A/m<2> to obtain the vanadium(II) solution, and recycling said solution to the leaching stage; oxidation of vanadium(IV) to vanadium(V); extraction of vanadium(V) with aliphatic amines, treated with sulphuric acid; reextraction of vanadium(V) in the presence of ammonium persulphate; passing the sulphuric acid through the layer of the solid ammonium vanadate obtained at a weight ratio of 1:2 to 3 to produce vanadium pentoxide; evaporation to dryness and crystallization of the raffinate obtained after the extraction to produce potassium alum; evaporation to dryness and crystallisation of the solution produced after ammonium vanadate has been isolated therefrom, to obtain ammonium sulphate.