Presentation Information
[3207]Electrowinning of Tin in Alkaline Stannate Solutions: Effects of Impurity Ions on Electrodeposition Behavior
○Jonghwan CHOI1, Yu-ki TANINOUCHI1, Hiroki OGAWA1, Hiroaki NAKANO1 (1. Kyushu University)
Chairperson: 宮下 匠人（北海道大学）
Keywords:
Electrodeposition,Tin,Stannate bath,Alkaline solution,Impurities
Alkaline stannate baths are widely used for the electrowinning of tin. With the increasing diversity and complexity of feed materials in smelting and recycling processes, various impurity ions may contaminate the electrolyte. However, their effects on the electrodeposition behavior of tin have not been sufficiently understood. In this study, the effects of selected impurity metal ions, including Zn(II), on tin electrodeposition from a Na2SnO3–NaOH solution were investigated. Electrodeposition was carried out at 70 °C under unstirred conditions using galvanostatic and potentiostatic methods. Among the impurity ions examined, Zn(II) showed characteristic behavior. Although Zn is thermodynamically less noble than Sn, it was preferentially incorporated into the deposit via anomalous co-deposition. This is mainly attributed to the sluggish kinetics of the reduction of stannate ions to metallic tin. It was also found that Zn co-deposition can be suppressed by controlling the cathode potential within an appropriate range.