LLC “UMMC-Holding”, Ekaterinburg, Russia:

S. A. Yakornov, Deputy Technical Director
A. M. Panshin, Technical Director

Technical University of UMMC, Verkhnyaya Pyshma, Russia:
P. A. Kozlov, Deputy Director (Scientific-Research and Project Institute on Science), e-mail: p.kozlov@tu-ugmk.com

Chelyabinsk Zinc Plant, Chelyabinsk, Russia:
D. A. Ivakin, Head of Technological Bureau of Engineering Center

Alkali hydrometallurgical technology, used during the development of a method of processing of dusts of electric-arc steel furnaces makes possible the selective extraction of zinc, remaining iron in solid residue. For the increase of zinc extraction before the alkali treatment of dusts, electric-arc steel furnaces undergo the high-temperature calcination together with calcium oxide. At the same time, zinc is transferred in the free oxide form and its solubility in acids and alkalies increases. We carried out the investigations of thermodynamic and kinetic parameters of the process of interaction of zinc oxide in composition of calcinated dust of electric-arc steel furnace (clinker) with NaOH in water solution with the temperature of 60–100 ^oC. According to our investigations, zinc can be dissolved with formation of hydroxocomplexes [Zn(OH)₄]^2– and [ZnO₂]^2– with the medium pH higher than 14. At the same time, reaction equilibrium displaces to the formation of zincates with 10–15-fold excess of alkaline with reference to zinc. Diffusion mode of reactions leading to zinc dissolution is shown. Activation energy in the temperature range of 70–95 ^oC is 9.6 kJ/mole. This process can apply the model, described by the generalized equation of heterogeneous process with solvent excess. The investigation results showed the technical possibility and efficiency of dissolution of the products, containing zinc oxide (including electric-arc steel furnace dusts after the considered pyrometallurgical preparation), in alkaline solutions with selective extraction of zinc in solution. Alkaline zincate solutions are subsequently purified from impurities and used for zinc extraction using electric extraction with zinc powder obtaining. Spent zincate electrolyte is secondly used for further cycles of zinc dissolution.

1. Panshin A. M., Leontev L. I., Kozlov P. A., Dyubanov V. G., Zatonskiy A. V., Ivakin D. A. Reprocessing technology of electric arc furnace dust Join Stock Company “Severstal” in Waelz treating of complex Join Stock Company “Chelyabinsk Zink Plant”. Ekologiya i promyshlennost Rossii. 2012. No. 11. pp. 4–6.
2. Das B., Prakash S., Reddy P. S. R., Misra V. N. An overview of utilization of slag and sludge from steel industries. Resources, Conservation & Recycling. 2007. Vol. 50. pp. 40–57.
3. Gökhan Orhan. Leaching and cementation of heavy metals from electric arc furnace dust in alkaline medium. Hydrometallurgy. 2005. Vol. 78, No. 3–4. pp. 236–245.
4. Frenay J., Hissel J., Ferlay S. Recovery of lead and zinc from electric steelmaking furnace dusts by the Cebedeau process. Recycle and Secondary Recovery of Metals. Warrendale, PA : TMS, 1985. pp. 195–208.
5. Mordogan H., Cicek T., Isik A. Caustic soda leach of electric arc furnace dust. Journal of engineering and environmental science. 1999. Vol. 23. pp. 199–207.
6. Ferlay S., Weill P. Alkaline zinc hydrometallurgy: an opportunity for the treatment of complex ores (Zimaval techn.). The 40 Conference of Metallurgists (COM 2001). Toronto, 26–29 august 2001. pp. 41–51.
7. Favorskaya L. V., Stolyarova E. I. Ratio of decomposition of zinc oxidated minerals by caustic soda solution. Izvestiya AN KazSSR. Seriya gornogo dela, stroymaterialov i metallurgii. 1956. No. 6. pp. 92–103.
8. Gurmen S., Emre M. A laboratory-scale investigation of alkaline zinc electrowinning. Minerals Engineering. 2003. Vol. 16, No. 6. pp. 559–562.
9. St-Pierre J., Piron D. L. Elecrowinning of zinc from alkaline solutions at high current densities. Journal of Applied Electrochemistry. 1990. Vol. 20, No. 1. pp. 163–165.
10. Liu Jidong, Su Jialin, Lu Jianhua, Zheng Songzhang, Liu Guocheng. Thermodynamic analysis on system of ZnO – NH₃ – NH₄HCO₃ – H₂O in process of zinc oxide leaching. Inorganic Chemicals Industry. 2015. Vol. 47, No. 6. pp. 30–33.
11. Caravaca C., Cobo A., Alguacil F. J. Considerations about the recycling of EAF flue dusts as source for the recovery of valuable metals by hydrometallurgical processes. Resources Conservation & Recycling. 1994. Vol. 10. pp. 34–41.
12. Ruiz O., Clemente C., Alonso M., Alguacil F. J. Recycling of an electric arc furnace flue dust to obtain high grade ZnO. Journal of Hazardous Material. 2007. Vol. 141, No. 1. pp. 33–36.
13. Jarupisitthorn C., Pimtong T., Lothongkum G. Investigation of kinetics of zinc leaching from electric arc furnace dust by sodium hydroxide. Material Chemistry and Physics. 2002. Vol. 77. pp. 531–535.
14. Dreisinger D. B., Peters E., Morgan G. The hydrometallurgical treatment of carbon steel electric arc furnace dusts by the UBC-Chaparral process. Hydrometallurgy. 1990. Vol. 25. pp. 137–152.
15. Baram I. I. Macrokinetics of heterogeneous processes. Alma-Ata : Nauka, 1986. 209 p.