WPA-TBP体系中多组份萃取行为的研究

Study on Extraction Performances of Multi-component in Wet Process Phosphoric Acid-Tributyl Phosphate System

为了了解湿法磷酸(WPA)中的H3PO4、杂质和水50℃时在磷酸三丁酯-煤油(TBP)体系中的萃取率和分配系数,以及TBP对WPA中各组分的选择性系数和水的协同萃取情况,针对WPA-TBP-煤油萃取体系,对酸中的主要组分(H3PO4,H2O,TBP)、杂质在有机相的萃取率和杂质在水相、有机相的分配以及TBP对H3PO4、杂质的选择性和水的协同萃取进行了研究.结果表明,在WPA中H3PO4浓度在5%~75%P2O5,TBP对杂质的萃取能力顺序为:Al3+【Mg2+【SO42-【SiF62-【Fe3+,在相比6~7时,杂质(Mg2+,Al3+,Fe3+,SO42-)选择性系数为1.5~2.2,达到最小值,而SiF62-达到最大值1.5,因此相比6~7为分离净化湿法磷酸中磷酸和杂质的最优条件。

This work concerns the extraction ratio and distribution of the multi-component in wet process phosphoric acid (WPA) by solvent extraction with tri-butyl phosphate at 50℃,selection coefficient of TBP and co-extraction of water. An exhaustive study of the multi-component extraction system WPA-TBP was carried out. First,the distributions of main components (H3PO4,H2O,TBP) and major impurities of WPA (Mg2+,Al3+,Fe3+,SO42-,SiF62-) between the aqueous and organic phases were systematically studied. Then selectivity of TBP for H3PO4 against the impurities and water co-extraction in the organic phase was expressed in a linear equation. The result shows that when the concentration of H3PO4 was in 5%~75% P2O5, the extraction power of TBP followed the order of Al3+<Mg2+<SO42-<SiF62-<Fe3+; when the phase ration was 6~7,the selection coefficient of impurities (Mg2+,Al3+,Fe3+,SO42-) was the minimum,1.5~2.2,but SiF62was the maximum,1.5,so the phase ratio,6~7,was the best condition for purification process of WPA,however,the co-extraction of H2O in the organic phase was reduced for the impurities in WPA.