化学沉淀分离-置换法提纯Al_(13)的工艺研究

Separation and Purification of Al_(13) by Chemical Precipitation and Metathesis

采用AlCl3溶液和Na2CO3粉末在不同温度下制备了不同浓度的聚合氯化铝（PACl）．以选定的中等浓度、高Al3含量的PACl为原液，研究了Al13与硫酸盐沉淀反应过程中SO4/Al摩尔比、反应体系起始总铝浓度的影响以及Al13硫酸盐与Ba（NO3）2置换反应过程中的Ba／SO4摩尔比、超声、温度等因素的影响．实验结果表明，在制备温度为50℃条件下，浓度在0．4-0．6mol／L范围的PACl含有较高的Al13沉淀分离反应的最佳SO4／Al摩尔比为0．6：1；生成的Al13硫酸盐沉淀物为正四面体状晶体．在Al13硫酸盐与Ba（NO3）2溶液置换反应过程中，Ba／SO4的最佳摩尔比为1：1，反应温度及超声作用对置换反应的影响较小；提高Ba（NO3）2的起始浓度可以得到相应较高浓度的纯化Al13溶液．所得Al13纯度的统计平均值为92．1％．

PACl3 with different concentrations were prepared by adding sodium carbonate powder into AlCl3 solution. Medium concentration and high Al13 content of PACl was chosen to carry out Al13 separation processes. The influences of SO4/Al molar ratio and the initial total Al concentration on the precipitation reactions of sulfate with different Al species were investigated. The factors influencing the metathesis reaction between solid Al13-SO4 and Ba（NO3 ）2 were evaluated. Results showed that high Al13 PACl could be obtained at the medium high eoaeentration range of 0.4 - 0.6 mol/L, the optimum SO4/Al ratio was 0.6：1 for precipitation- separation of Al13, Al13-SO4 precipitates were mostly consisted of tetrahedral crystals. During the metathesis reaefion, Ba/SO4 molar ratio of 1 ： 1 is the optimal value. Small range temperature variation and ultrasonic action had no marked influence on metathesis reaction rate and final Al13 concentration. Higher initial Ba（NO3 ）2 concentration could produce higher concentration Al13 accordingly. The purity of Al13 solution could be reached to 92.1% statistically.