P507萃取纯化V(Ⅳ)制备草酸氧钒及其物化性能

Preparation of Vanadium Oxalate by Solvent Extraction and Purification with P507 and Its Physicochemical Properties

从钒渣钠化焙烧后的含钒浸液中,采用2-乙基己基磷酸单-2-乙基己酯(P507)萃取-草酸反萃取-蒸发结晶新工艺制备了草酸氧钒,优化了草酸反萃取工艺的条件.研究结果表明,采用2. 0 mol/L草酸溶液,在水相与有机相体积比V(A)∶V(O)为1∶5时,于50℃下经过三级(理论)反萃取,钒的反萃取率可达到99. 98%,反萃取液中VOC_2O_4浓度可达290. 0 g/L以上.负载的反萃取液经膜过滤除去残留有机物后,再经蒸发结晶得到草酸氧钒.采用X射线衍射、X射线能谱、热场发射扫描电子显微镜及同步热分析等手段表征了草酸氧钒的物化性能,结果表明,草酸氧钒的结构为VOC_2O_4·2H_2O,粒度分布均匀,结晶度高.

Vanadium oxalate is an ideal precursor used for the preparation of vanadium containing catalysts,advanced phase change material of VO2,high performance VN and other vanadium based chemical products.Currently,few research on the preparation of VOC2O4 was found to be reported.In this study,highly pure vanadium oxalate was prepared through'extraction-stripping-evaporative crystallization'method using2-ethylhexyl dihydrogen phosphate(P507)as the extractant and H2C2O4 as the stripping reagent from a vanadium leach solution obtained by sodium roasting and water leaching of vanadium titano-magnetite slags.V(Ⅳ)stripping from the loaded P507 solution with H2C2O4 was emphatically studied and the stripping conditions were optimized.The result showed that vanadium could be almost completely(99.98%)stripped at an A/O ratio of 1∶5 and 50℃using 2.0 mol/L oxalic acid solution in three stages(theoretical).The concentration of VOC2O4 would reach 290 g/L in the loaded strip liquor.The vanadium oxalate was characterized by X-ray diffraction(XRD),energy dispersive spectrometer(EDS),field emission scanning electron microscope(SEM)and synchronous thermal analyzer(TGA-DSC).The result showed that vanadium oxalate was VOC2O4·2H2O and it had high purity,good crystallinity and average particle size distribution.