| There is no harmful gas produced for the atmospheric sulfuric acid leaching of non-roasting vanadium slag,but a strong acidic leaching condition is required.As a result,the leaching solution is of high acidity and has high content of impurities（e.g.,Fe,Cr,et al）.The solvent extraction was employed to separation and enrichment of V to provide theoretical and technical support for clean production of vanadium slag.The E-pH and composition diagram analysis show that V,Fe and Cr mainly exist as VO2+,VOSO4;Fe2+,Fe HSO4+,Fe SO4,Fe HSO42+,Fe SO4+,Fe（SO4）2-and Cr3+,Cr SO4+,Cr OHSO4,respectively.The bifunctional ionic liquid[A336][P507]system is chosen from the selected six categories of extraction system.After optimization,the extraction conditions are:p H=1.40,0.5 mol/L[A336][P507]-10%TBP-260#solvent oil,O/A=1:1,3 min.The extraction rates of V,Fe and Cr are98.53%,8.46%and 5.49%respectively.The washing conditions are:0.3 mol/L Na2SO3,O/A=2:1,5 min.The stripping conditions are:3 mol/L H2SO4,O/A=6:1,5 min.The stripping rates of V,Fe and Cr are 75.54%,2.13%and 0.41%respectively.Regeneration conditions are:1 mol/L Na OH,O/A=1:1,5 min.After two-stage countercurrent extraction,washing,three-stage countercurrent stripping,the V in rich vanadium liquid is20.010 g/L,the other elements is low,and can meet requirements.The extraction mechanism is neutral complexation with[A336][P507]to V（Ⅳ）through VO2+and VOSO4,H+and SO42-are co-extracted.The extraction ratio drawn by slope method,saturation capacity method and equimolar series method ranges from 2 to 4.The FT-IR of organic phase shows hydrogen bond and ionic bond are formed between[A336]+and[P507]-.With the inner synergistic effect of the groups,[A336][P507]is of strong extraction and selectivity for V（Ⅳ）.After extraction the new force appears between P═O and V═O.The organic phase cycling and FT-IR verified its stability.Thermodynamics shows the extraction is spontaneously exothermic,ΔH=-15.68 k J/mol.Figure 46;Table 19;Reference 115... |
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