微分散轮盘塔萃取净化湿法磷酸的实验研究

Experimental study on purification of wet-process phosphoric acid in micro-dispersion rotating disc column

采用筛网孔径为75μm的微分散轮盘萃取塔净化湿法磷酸,在TBP+煤油/磷酸/水为体系的实验条件下,研究了浓度为55%的湿法磷酸的萃取及反萃特性,考察了不同转速、总体积通量和相比对萃取率和反萃取率的影响。研究结果表明,萃取率随转速及相比的增大而增大,随总体积通量的增大而减小,最优萃取条件:转速为250 r/min,总体积通量为56.62 L/(m2.min),相比为4,磷酸萃取率可达55%;反萃率随转速的增大而增大,随相比及总体积通量的增大而减小,最优反萃条件:转速为300 r/min,总体积通量为56.62 L/(m2.min),相比为6,磷酸反萃率可达85%。通过量纲为1化拟合出体积传质系数经验计算式为KXa=1.53×10 3p 0.28135Fr0.344493W/D,与实验规律吻合,可以为工业放大设计和优化提供了较好的实验依据。

The mesh size of 75 gm of micro-dispersion rotating disc column was used to purify wet-process phosphoric acid with the system of TBP＋kerosene/phosphoric acid/water. The effects of rotate speed, volume flow, phase ratio on the extraction and re-extraction of phosphoric acid with the content of 55% were studied. Results showed that the extraction rate increased with the increase of rotate speed and phase ratio, and decreased with the increase of volume flow. Under the optimum conditions of rotate speed of 250 r/min, volume flow of 56.62 L/（m2·min）, phase ratio of 4, and the extraction rate can be as high as 55%. The re-extraction rate was improved with the improvement of rotate speed, fell with the raise of phase ratio and volume flow. Under the best re-extraction conditions of rotate speed of 300r/min, volumetric flow of 56.62 L/（m2·min） phase ratio of 6, the re-extraction rate could be up to 85%. Non-dimensional expression for the volumetric mass transfer coefficient can be expressed asKxa=l.53 × 10 3p o.28135FrO.344493W/D, and the simulation matched the experimental results. The application of this model could provide a good experimental basis for industrial scale-up design and optimization.