Effect of Solution Coordination Environment on Extraction of Vanadium(Ⅳ)by P204
The effects of solution coordination environment on the extraction of vanadium by P204 were investigated.The effects of chloride,fluoride and sulfate ions on the extraction of vanadium and their coordination with vanadium were examined at different pH.The results show that for the extractant using an organic phase composition of 20％ P204+5％ TBP+75％ sulfonated kerosene,at phase ratio of VO/VA=1/2 and extraction time of 8 min,chloride ions can effectively enhance vanadium extraction.At pH=1.0 and[Cl-]=5 mol/L,the vanadium extraction can reach 87.93％.When the pH is 1.4～2.2,fluoride ions in a certain concentration range can promote the extraction,and the best promotion effect is achieved when[F-]=0.05 mol/L.The concentration of fluoride ion is greater than 0.2 mol/L,and the extraction is inhibited.When pH=1.8 and 2.2,the concentration of sulfate has little effect on vanadium extraction.But when pH=1.0 and[SO42-]=1.5 mol/L,the vanadium extraction rate is only 52.22％,and the high concentration of sulfate can significantly inhibit vanadium extraction.The thermodynamic results show that coordination groups VOC1+ and VOF+ can enhance vanadium extraction process.When the concentration of fluoride ion is higher than 0.2 mol/L,the coordination anion VOF3 formed by VO2+ and multiple F- prevents the cation exchange reaction of P204.
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