SEPARATION AND PURIFICATION OF VANADIUM AND MOLYBDENUM BY SOLVENT-EXTRACTION FOLLOWED BY REDUCTIVE STRIPPING

The solvent extraction of vanadium and molybdenum by tri-n-oetylmethylammonium chloride (TOMAC) from neutral solutions was studied and it was found that vanadium was extracted preferentially by an anion exchange mechanism. The pentavalent vanadyl anion in the organic solution was found to be reduced to the form of tetra- or trivalent cations by contact with an aqueous solution containing a reduction agent such as L-ascorbic acid. This enables the vanadium to be stripped selectively by chemical reduction, with the molybdenum remaining in the organic phase. A separation efficiency of 1.64 x 104 was obtained for an aqueous solution containing initially equal concentrations of the two metals by single extraction followed by single selective stripping. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.