P204/4PC协同萃取分离镍钴与镁钙的研究

采用新型协同萃取剂P204/4PC从含少量镍钴钙的硫酸镁溶液中选择性萃取镍和钴, 考察了萃取剂浓度、平衡pH值等因素对萃取分离效果的影响, 绘制了萃取、反萃取等温线, 并进行了串级模拟萃取-反萃取全流程实验。研究结果表明: P204/4PC协同萃取剂能从硫酸镁溶液中选择性萃取镍钴, 实现镍钴与钙镁的高效分离以及镍钴的高倍富集回收。模拟串级全流程实验结果显示, 对于含镍1.68 g/L、钴0.10 g/L、镁15.68 g/L和钙0.11 g/L的料液, 采用组成为0.25 mol/L P204+0.5 mol/L 4PC+磺化煤油的有机相经5级逆流萃取-1级洗涤-6级反萃取, 萃余液中镍和钴含量均小于0.01 g/L, 镍和钴萃取率均达到99.5%以上;反萃液中镍和钴浓度分别达到40.4 g/L和1.8 g/L, 杂质钙和镁浓度分别为0.02 g/L和0.09 g/L, 全流程钙镁除去率分别达到99.97%和99.36%。

Separation of Nickel/Cobalt and Magnesium/Calcium Using Synergistic Extraction System of P204/4PC

A new type of synergistic solvent extraction system consisting of P204/4PC was adopted to selectively extract nickel and cobalt from the magnesium sulfate solution containing a small amount of nickel, cobalt and calcium. The effects of factors, including extractant concentration and equilibrium pH on the extraction effect were investigated. Then, the extraction and stripping isotherms were generated. A simulation experiment of the whole process of cascade extraction and stripping showed that synergistic extraction system consisting of P204/4PC can selectively extract nickel and cobalt from magnesium sulfate solution, which can achieve the high-efficiency nickel/cobalt separation and calcium/magnesium separation, as well as high efficient of enrichment and recovery of nickel and cobalt. It is shown from the test that the liquid material, containing 1.68 g/L Ni²⁺, 0.10 g/L Co²⁺, 15.68 g/L Mg²⁺ and 0.11 g/L Ca²⁺, is subjected to a process consisting of 5-stage countercurrent extraction, 1-stage washing and 6-stage stripping by using the organic phase of sulfonated kerosene with the composition of 0.25 mol/L P204 and 0.5 mol/L 4PC, resulting in the content of nickel and cobalt in the raffinate less than 0.01 g/L and both the extraction rate of nickel and cobalt exceeding 99.5%. The concentration of nickel and cobalt in the stripping solution reached 40.4 g/L and 1.8 g/L, the concentration of impurities of calcium and magnesium were 0.02 g/L and 0.09 g/L respectively, and the removal rate of calcium and magnesium from the whole-process experiment reached 99.97% and 99.36%, respectively.