Co-extraction and selective stripping of vanadium (IV) and molybdenum (VI) from sulphuric acid solution using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester

摘要

2-Ethylhexyl phosphonic acid mono-2-ethylhexyl ester (EHEHPA) diluted with kerosene was used to co-extraction and selective stripping vanadium (IV) and molybdenum (VI) from sulphuric acid solution. The influence of aqueous pH, extractant concentration, stripping agents on the co-extraction and selective stripping of both metals were investigated. The extraction of both metals is sensitive to aqueous pH; however, molybdenum (VI) is extracted preferably to vanadium (IV) at acidic pH values. Both metals were co-extracted by a three-stage counter current extraction with 15%(v/v) EHEHPA at initial aqueous pH 2.0 and O/A phase ratio 1.0. Vanadium (IV) in the loaded organic phase was selectively stripped by 1.0 mol/L sulphuric acid. Molybdenum (VI) in the vanadium-free organic phase was completely stripped by aqueous solution containing 10 wt.% NH4OH and 15 wt.% NH4Cl with excellent phase separation. The separation factor of vanadium (IV) to molybdenum (VI) was 345. A process flow sheet has been developed to recover and separate vanadium (IV) and molybdenum (VI) from sulphuric acid solution.