Abstract
Primary amine can be used to separate vanadium(V) from chromium(VI) effectively in weakly alkaline solution by solvation mechanisms, as shown by earlier work. Separation of rhenium(VII) from molybdenum, tungstenfVI) from molybdenun, etc. can be very effectively carried out by using primary amine mixed with neutral donor reagents by synergistic solvation extraction. Experimental results indicate the presence of solvation extraction in addition to the ordinary anion exchange extraction with amines as solvent. Iron present in the sulfuric acid leaching solution as impurity gets extracted into the organic phase and is difficult to strip. Several mixed solvent systems with an amine and a neutral donor cxtractant have been developed for iron removal. These have common feature that the iron in the organic phase can be stripped with dilute sulfuric acid.