Abstmet
-Antimony electrodeposition from the molten Na$-Sb,S, system has been studied in the 8004000ยฐC tern ture $ra range as a function of temperature, cd value and molar composition of the melt. Current crencies increase with increasing cd and higher temperature, showing a maximum with the variation of Na,!I mole fraction in the bath. The high yields are attributed to an increase of ionic conductivity of the melt produced by the. sodium ions and higher temperature and to a decrease in the solubllity of antimony metal in the sulphide. -Man untersuchte die elektrolytische Abscheidung von Antimon aus einer Na,S/Sb,S&chmelze bei 800-1000ยฐC in Abhilngigkeit der Temperatur, der Stromdichte und der molaren Z wammensetzung der khmelze. Die Stromausbeute nimmt mit zunehmender Stromdichte, sowie such mit zunehmender Temperatur zu. Die Abh&rgigkeit der Stromausbeute vom Na,S-Gehalt in der Schmelze durchliluft em Maximum. Die grossen Ausbeuten sind einer Zunahme der Ionenleitfiihigkeit der Schmelze dank da Natriumionen, sowie einer Abnahme der L&slichkeit des metallischen Antimons im Sultid zuzuschreiben.
THP DIRECT electrolytic reduction of antimony from molten sulphide has been tried since Faraday's days. It exhibits the disadvantages of the mutual solubility of the liquid metal and sulphide phases as well as the large electronic conductivity of the melt. Vivienl was able to improve the ionic conductivity of the molten sulphide by adding to the melt 15 wt-% Na$, even though current e5ciencies hardly exceeded 10 per cent. Better yields were obtained by Yanagase and Derge,* who performed the electrolysis of a metal saturated solution of the sulphide subsequently to a phasediagram study of the system.
Recently, new attempts at antimony deposition from solutions of sulphide in oxysaltss and chloride mixtures4 have yielded rather good results in spite of the problems involved in handling the solvents. The Russian school5 has again undertaken the electrochemical study of the 15 wt-% Na$-Sb& mixture as a function of temperature and cd, producing current e5ciencies up to 60 per cent. As an extension of these results, new research on electrodeposition of antimony from the sodium-antimonysulphide system is now reported.
EXPERIMENTAL TECHNIQUE
The fused mixture of sulphides was prepared from Na$ and Sb,S in the required ratios. Na$l.lOH,O (Merck reagent grade) was first dried for 24 h in a vacuum oven