THE ELECTROCHEMICAL BEHAVIOUR OF Sb ELECTROWINNING IN Na_2S-NaOH SOLUTION
Jiang Hanying; Shu Yude; Zhao Ruirong; Gong Zhuqing; Yang Songqing (Central South Institute of Mining and Metallurgy; Changsha)
Cite this article:
Jiang Hanying; Shu Yude; Zhao Ruirong; Gong Zhuqing; Yang Songqing (Central South Institute of Mining and Metallurgy; Changsha). THE ELECTROCHEMICAL BEHAVIOUR OF Sb ELECTROWINNING IN Na_2S-NaOH SOLUTION. Acta Metall Sin, 1982, 18(3): 378-386.
Abstract By determining the polarization cureve, the discharge potentials of Sb (Ⅲ), Sn (Ⅳ), As (Ⅲ) and H~+ ions were obtain edas -0.92, -1.04, -0.81 and -1.12V respectively, which were checked with the thermodynamic calculation. Their dynamic parameters were estimated by the Tafel lines which resulted after modification of their concentration polarization. At 50℃, the rate constant was found to be 1.54×10~(-4) cm/s, the exchange current density 10~(-2) A/cm~2 and the activation energy 9100 cal/mole.The cathodic discharge mechanism of SbS_3~(3-) and SbS_4~(3-) has been investigated with the help of the chronopotentiometric method. It was shown that before charge transfer, the SbS_3~(3-) ions should be subjected to a prior chemical reaction, i. e. SbS_3~(3-)=SbS~++2S~(2-). The SbS~+ ions formed are then reduced to metallic Sb at the cathode. The discharge of SbS_4~(3-) ions at the cathode takes place in two steps: First, SbS_4~(3-) ions are directly discharged into SbS_3~(3-) and then further reduced into metallic Sb.
