振动筛板塔中杂质对湿法磷酸萃取体系的影响

Effect of Impurities on Extraction Purification of Wet Phosphoric Acid in Reciprocating Sieve Plate Extraction Column

利用热法磷酸配制模拟湿法磷酸,并用湿法磷酸在振动筛板塔中进行了4级萃取分离实验,考察了铁,硫,氟在不同萃取级数时对磷酸萃取率和杂质分离系数的影响.结果表明,随着相比提高,磷酸萃取率由12%上升至65%,且有机相的磷酸含量由12%降至3%P2O5.对多级萃取体系,单个和多种杂质共存时,随着萃取级数的增加,磷酸萃取率也随之升高到75%以上,杂质分离系数升高至0.70左右,但在多种杂质共存体系下,在反应级数大于3时,分离系数随之下降.3级分离萃取时,磷酸的萃取率能达到75%,而对Fe3+和SO42-分离系数最高达0.55和0.10左右,达到很好的净化分离湿法磷酸和杂质的效果.

The four-stage extraction and separation for purification of wet phosphoric acid (WPA) in the reciprocating sieve plate extraction column was studied,WPA was confected in the thermal phosphoric acid. The influence on the extraction ratio and distribution coefficient of WPA and impurity (SO42-,F-,Fe3+) was examined. The result showed that the extraction ratio of WPA increased from 12% to 65% and the concentration of P2O5 in the organic phase decreased from 12% to 3% P2O5. In the multistage extraction system,following the increase of extraction stage,the extraction ratio of P2O5 reached 75%,and the separation coefficient of impurities to about 0.70, but when the extraction stage number was more than 3, and several impurities coexisted in WPA, the separation coefficient decreased following the increase of stage. Compared with the single stage extraction system, the three-stage extraction could better purify the WPA,the extraction ratio of P2O5 reached 75%,and the separation coefficient of Fe3+ and SO42to the maximums,about 0.55 and 0.10,which can be the best process for separation of the impurities and P2O5.