Solvent Extraction of Molybdenum(VI) and Vanadium(V) from Sulfuric Acid Solution by Cyanex~R 600 in Orfom~R SX-12

摘要

Molybdenum and vanadium are extensively used as alloying elements in the manufacture of steel and other alloys. The widespread use of these metals encourages a growing need to develop extraction processes for their recovery, both from primary and secondary sources. Solvent extraction is one of the methods being progressively used for recovery of these metals. Cyanex~R600 solvent extractant has been developed for the recovery of molybdenum from acidic solutions originating from both low grade (e.g. copper solvent extraction raffinates, smelter dusts and slags) and high-grade (molybdenite) molybdenum sources. Cyanex~R600 has an active component, bis(2,4,4-trimethylpentyl)phosphinic acid and has been developed for improved selectivity towards molybdenum. The extraction efficiency of Cyanex~R600 in Chevron Phillips' Orfom~R SX-12 diluent was evaluated for Mo(VI) and V(V) in sulfur acid medium. The extraction of both metals is sensitive to the pH of the aqueous solution; however, quantitative extraction of Mo(VI) and V(V) was observed at pH 1.5. The uptake of Mo(VI) and V(V) increased with the increase in the concentration of Cyanex~R600. The approximate stoichiometry of the extracted complex was: Mo: Cyanex~R600 = 1:2. The V(V) species in the loaded organic phase could be efficiently scrubbed with 1 M and 2 M H_2SO_4. Effective stripping of Mo(VI) could be achieved with NH_4OH solutions.