Coordination separation pattern and extraction mechanism of germanium in zinc leaching solution by wet process
In view of the high cost and complicated process of recovery of enrichment of germanium from hydrothermal zinc solution,this paper thoroughly studied the effect of five different coordination agents on the selective separation and enrichment of germanium from the N235-TBP composite extraction system and the mass transfer mechanism of the tartaric acid system.The results show that,under the conditions of organic phase formation of 30％N235-15％TBP-55％260#solvent oil,O:A ratio of 1:2,pH 1.5,reaction temperature of 25℃,and molar ratio of complexing agent to germanium(nL/nGe)of 5,the coordination abilities of the 5.5 coordination agents to germanium are those tartaric acid(C4H6O6)>oxalic acid(C2H2O4)>citric acid(C6H8O7)>maleic acid(C4H4O4)>salicylic acid(C7H6O3).C4H6O6 had the best separation effect on Ge4+and impurity ions Zn2+and Fe2+.When nC4H6O6/nGe=5,the separation coefficients reach their maximum,respectively,βGe/Zn2+=2807.23,βGe/Fe2+=3271.43.The coordination form between C4H6O6 and germanium is bidentate(chelating)coordination.The mechanism of extracting germanium with N235-TBP composite extraction system is that HSO-4 undergoes anion exchange with Ge(OH)2Tar2-in the feed solution,resulting in the extraction coordination((R3 NH+)2·(Ge(OH)2Tar22-)·TBP0.3).
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