JSC Uralelektromed, Verkhnyaya Pyshma, Russia:

N. E. Agarova, Lead Process Engineer of the Electrochemical Production Laboratory of the Research Center, e-mail: N.Agarova@elem.ru
A. A. Kozmina, Process Engineer of the Electochemical Production Laboratory of the Research Center, e-mail: A.Kozmina@elem.ru
L. M. Yakovleva, Head of the Electochemical Production Laboratory of the Research Center, e-mail: L.Yakovleva@elem.ru

UMMC Technical University, Verkhnyaya Pyshma, Russia:
S. A. Krayukhin, Science Director

For selective extraction of antimony and tin from the sludge resulting from final filtration of the spent process solutions of the main production sites of JSC “Uralelektromed” a process flowsheet has been developed and implemented to obtain antimony-tin concentrate for further production of antimony-tin alloy for soldering. To improve the process of antimony-tin concentrate precipitation from alkaline-sulfide electrolyte the anodic polarization was investigated and lab experiments including identification of process and economic parameters were performed. The electrode processes were researched using polarization curves method. Regression analysis showed that alkali concentration affects the anode potential 4–5 times stronger than sodium sulfide at current density of 1000 A/dm². It was concluded that electrolyte should contain at least 70 g/dm³ of sodium hydroxide and 40–80 g/dm³ of sodium sulfide. In this case, anode adverse reactions and increased voltage in the cell are excluded. The experimental results identified adverse influence of electrolyte intensive circulation on formation of cathode deposit and thus the main laboratory tests were performed with stationary electrolyte. Current density and cathode-anode gap were variable parameters. The electroextraction was carried out with depleted electrolyte, i.e. without its replenishing with fresh portion. The initial electrolyte composition g/dm³: antimony — 14.0 to 16.0; tin — 16.1 to 18.16; arsenic — 8.6 to 19.3; sodium hydroxide — 64 to 81; sodium sulfide — 47 to 66. The best process and economic parameters were obtained for one-stage process with residual concentration of antimony and tin of less than 2 g/dm³ and 12 g/dm³ respectively. The antimony-tin concentrate contained 62.0% of antimony and 36.6% of tin. The study shows that the reduction of anode current density increases the current yield while the decrease of inter-electrode space reduces the power consumption. It was concluded that it is unpractical to further extract tin from spent solutions after antimony-tin concentrate precipitation without additional treatment.

1. Korolev A. A., Mastyugin S. A., Fineev D. S., Voinkov R. S. et al. Method of extracting antimony and lead. Patent RF, No. 2590781. Applied: 04.03.2015. Published: 10.07.2016. Bulletin No.19.
2. Zemnukhova L. A., Makarenko N. V. Procedure for production of metallic antimony out of antimony raw material. Patent RF, No. 2409686. Applied: 08.04.2010. Published: 20.01.2011. Bulletin No.2.
3. Сhen Wei, Yang Bin, Tang Wen Tong et al. Method for separating antimony from tin-antimony alloy by vacuum distillation. Patent CN, No. 104651627. Applied: 05.02.2015. Published: 27.05.2015.
4. Zuo Liangcai, Song Zuxin. Method for extracting valuable metallic tin component from antimony and tin smelting alkaline residues through water leaching neutralized tin settlement. Patent CN, No. 106244816. Applied: 28.08.2016. Published: 21.12.2016.
5. Yang Jian-Guang, Fang Yafei et al. The method of recovering crude tin from tin slag refining. Patent CN, No. 104152701. Published: 13.06.2017.
6. Antimony. Ed. by S. M. Melnikov. Moscow : Metallurgiya, 1977. 536 p.
7. Adilova A. A., Polyvyannyy I. R., Lata V. A., Donskikh D. K. Method of recovering antimony from alkaline sulfide solutions. Author’s certificate SU, No. 1737011А1. Applied: 09.07.1990. Published: 30.05.1992. Bulletin No. 20.
8. Zharmenov A. A., Kozlov V. A., Zhakanov K. Sh. Method of processing antimony raw materials. Patent KZ, No. B27812. Applied: 17.04.2012. Published: 18.12.2013. Bulletin No.12.
9. Andreev Yu. Ya., Kutyrev A. E. Electrochemical methods of research on metals and alloys. Moscow : MISiS, 2009. 68 p.
10. Rotinyan A. L., Tikhonov K. I., Shoshina I. A., Timonov A. M. Theoretical electrochemistry. Moscow : Student, 2013. 494 p.
11. Vetter K. Electrochemical kinetics. Moscow : Khimiya, 1967. 856 p.
12. Shiyanov A.G. Antimony production. Moscow : Metallurgizdat, 1961. 176 p.
13. GOST 860–75. Tin. Specifications. Introduced: 01.01.1977.