National University of Science and Technology “MISiS”, Moscow, Russia:

A. P. Lysenko, Professor at the Department of Non-Ferrous Metals and Gold, Candidate of Technical Sciences, e-mail: reikis@yandex.ru
E. A. Shevchenko, Master’s Student at the Department of Non-Ferrous Metals and Gold, e-mail: ShevchenkoE.A@yandex.ru

This paper examines the main techniques for producing secondary aluminium from dump aluminium smelter slags. All the considered techniques can be divided into two major groups: mechanical and hydrometallurgical techniques. The mechanical techniques imply separation of metals from minerals in the slag, whereas the hydrometallurgical techniques are designed to separate salts from oxides. Because the described techniques are not designed to process all the slag components, they have not been implemented on industrial scale. The authors looked at an advanced method for disposal of dump aluminium slags. The method involves water leaching of salts, filtration, evaporation of supernatant solution (which results in the production of covering and/or cleaning fluxes containing sodium and potassium chlorides), electrolysis of the solid residue after melt leaching of sodium fluoride and aluminium fluoride salts and producing a deoxidizer alloy. The applicability of this alloy as a deoxidizer and its compliance with GOST 295–98 have been confirmed. The paper describes the chemical composition of deoxidizer alloys obtained from secondary raw materials. The pilot testing of the proposed technique conducted at the facilities of Bogaevsky Mine and MISiS’ base Teply Stan proved that the technique can be efficiently used to process dump aluminium slags. Thus, the recovery of salts reached 88.4%, the current efficiency – 87%. Experiments helped determine the chemical composition of oxides contained in the slag. The paper examines a deoxidizer introduction process by considering the case study of steel produced in an electric arc furnace and further refined in a ladle furnace. Recommendations are given for the development of an efficient introduction process for secondary aluminium as a deoxidizer for steel.

1. Tribushevskiy L. V., Nemenenok B. M., Rumyantseva G. A., Gorbel I. A. Wasteless technology of processing aluminium chips and slags in a short-flame rotary furnace. Lite i Metallurgiya. 2017. No. 4. pp. 109–118.
2. Leontiev L. I., Ponomarev V. I., Sheshukov O. Yu. Recycling and disposal of steel industry wastes. Ekologiya i promyshlennost Rossii. 2016. Vol. 20, No. 3. pp. 24–27.
3. Tribushevskiy L. V., Nemenenok B. M., Rumyantseva G. A., Kulik M. A. Steel refining using secondary aluminium recycling wastes. Lite i Metallurgiya. 2018. No. 1. pp. 100–105.
4. Tribushevskiy L. V., Nemenenok B. M., Rumyantseva G. A. How the scrap aluminium melting process influences the composition and applicability of the resultant dust. Lite i Metallurgiya. 2018. No. 3. pp. 118–124.
5. Tolaymat Thabet, Xiaolan Huang. Secondary aluminum processing waste: salt cake characterization and reactivity. EPA Report. U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Waste Management Branch. Last updated – September 19, 2017.
6. Lysenko A. P., Puzanov D. S. Recycling of oxide salts resultant from secondary aluminium production: Targets and prospects. Bulletin of Moscow State Open University. Series: Engineering and Technology. 2011. No. 3. pp. 10–15.
7. Lysenko A. P., Selnitsyn R. S. Recycling of dump secondary aluminium slags. Bulletin of Moscow State Open University. Series: Engineering and Technology. 2013. No. 1. pp. 11–18.
8. Lysenko A. P., Selnitsyn R. S. Method to process salt aluminium-containing slags to produce flux covers and aluminium process alloys. Patent RF, No. 2491359. Published: 27.08.2013. Bulletin No. 24.
9. Okunev V. M. Research and development of a hydrometallurgical technique to process aluminium salt slags: PhD dissertation. Moscow, 1979. 171 p.
10. Lysenko A. P., Selnitsyn R. S. Processing of low-grade alumina for obtaining of steel deoxidants in aluminum electrolyzers. Tsvetnye Metally. 2015. No. 3. pp. 14–20.
11. Ruzinov L. P., Gulyanitskiy B. S. Equilibrium transformations in metallurgical reactions. Moscow : Metallurgiya, 1975. 416 p.
12. Reference book in thermodynamics. TBASE. Moscow : KoMet, 1992. 57 p.
13. Morachevskiy A. G., Sladkov I. B. Thermodynamic calculations in metallurgy: Handbook. Moscow : Metallurgiya, 1985. 136 p.
14. HSC Chemistry 5.11: A software programme for thermodynamic calculations. Outokumpu Finland. 2002.
15. Кiss Laszlo, Poncsak S., Antille J. Simulation of the bubble layerin aluminum electrolysis cells. Light Metals. 2005. p. 559.
16. Businger A. Neues Verfahren fur die Aufarbeituag von Aluminium Kratzen. Metall. 1961. No. 10. p. 1014.
17. Rolin M. Conductivite electrique des melanges a base de cryolithe fondue: Systemes NaF-AlF₃, AlF₆Na₃-Al₂O₃ et AlF₆Na₃-CaF₂. Electrochimica Acta. 1972. Vol. 17, Iss. 12, December. pp. 2293–2307.
18. GOST 295-98. Aluminium for deoxidation, manufacture of ferroalloys and aluminothermy. Specifications. Introduced: 2001.07.01.