Separation of V and Cr from alkaline aqueous solutions using acidified primary amine A-N1923-sodium tartrate system

A novel liquid-liquid solvent extraction approach was studied by using acidified primary amine A-N1923- sodium tartrate system to separate V and Cr in strongly alkaline aqueous solution. The distribute behavior of Al during the process of extraction and separation of V and Cr was also investigated. The experimental results reveal that co-extraction of V and Cr can be avoided if previously adding sodium tartrate into the aqueous solutions. An effective separation of V and Al from Cr can be achieved even when NaOH concentration is above 0.1 mol/L. The concentrations of sodium tartrate, initial aqueous alkalinity, initial metal ion concentration ratios of V to Cr, extraction phase volume ratio of A/O and the concentration of extractant, acidified primary amine N1923, have significant influence on the separation of V, Cr and Al. When aqueous pH value is between 10 and 13, the separation factors of V/Al and V/Cr can reach 89 and 60, respectively. The extraction loading capacity of V in organic phase can reach 5.855 g/L at 298 K. After extraction, Al can be stripped selectively from the loaded organic phase by 0.5 mol/L sodium nitrate solution, and then, V can be stripped by 1.5 mol/L sodium nitrate solution. The organic phase could be re-used after stripping of V and Al. The present work provides a new strategy to extract and separate V and Cr from the strongly alkaline leaching solution produced by sub-molten salt method for treating the high chromium vanadium-titanium magnetite ores from Panzhihua in China.