电渗析法从磷酸铁生产母液中分离杂质金属离子

以各种回收的资源（磷酸铁锂正极粉、钛白副产品硫酸亚铁等）为原料生产磷酸铁时，产生的磷酸母液会逐渐富集Li+、Na+、Ca2+、Mg2+、Mn2+、Ni2+、Al3+等金属离子杂质，需要分离金属离子，以便磷酸回用。采用电渗析法对磷酸母液进行净化除杂，并探索了电流密度对除杂效率的影响。结果表明，在较合理的工艺参数长期运行的条件下，各杂质离子的去除率为（%）：Li+ 41.18、Na+ 54.55、Ca2+ 64.29、Mg2+ 54.02、Mn2+ 35.71、Ni2+ 46.38、Al3+ 16.67，除杂后的磷酸母液可重新用于磷酸铁的生产，避免了磷资源的损失。电流密度的增加会增加电耗，降低电流效率，而在电解液替换流量与电流量的比相同的条件下，杂质去除率也会降低。较优的运行电流密度为2 A/dm2。使用阳离子膜面积为1 dm2的电渗析装置时，磷酸铁母液除杂处理量为52.14 mL/h，阴极液（150 g/L硫酸溶液）的消耗量为10.41 mL/h。

Removal of Impurity Metal Ions from Mother Liquor of FePO4 Production by Electrodialysis Method

In the process to produce FePO4 which uses recycled resources such as spent LiFePO4 and Fe2SO4 (byproduct in producing TiO2), the mother liquor will concentrate cationic impurities such as Li+, Na+, Ca2+, Mg2+, Mn2+, Ni2+, and Al3+. The impurity ions of mother liquor should be removed so that the phosphoric acid can be reused. Impurities were removed from FePO4 mother liquor by electrodialysis method. Effect of current density on purification efficiency was explored. The results show that removal rate of impure ions is Li+ 41.18%, Na+ 54.55%, Ca2+ 64.29%, Mg2+ 54.02%, Mn2+ 35.71%, Ni2+ 46.38%, and Al3+ 16.67% under the condition of long-term operation with reasonable process parameters. After removing the impurities, the mother liquor can be used in producing FePO4 which prevents the loss of phosphorus resources. When the current density rises, the power consumption rises and the current efficiency drops. At the same time, the impurity removal rate drops under the same ratio of replacement amount of flow of electrolyte to current flow. The optimal operating current density is 2 A/dm2. By using the electrodialysis device with cationic membrane area of 1 dm2, the impurity removal capacity of FePO4 mother liquor is 52.14 mL/h and the consumption of cathode liquid (150 g/L sulfuric acid solution) is 10.41 mL/h.