Empress Catherine II Saint Petersburg Mining University (Saint Petersburg, Russia)
Piirainen V. Yu., Professor, Doctor of Engineering Sciences, Professor, piraynen@gmail.com
Barinkov V. M., Postgraduate Student, barinkov1996@yandex.ru

The growing scarcity of natural resources necessitates the efficient and integrated use of raw materials. One promising direction involves repurposing iron-bearing waste from alumina production as a supplementary feedstock in ferrous metallurgy. Despite extensive research, large-scale implementation of this approach remains limited. Utilizing anthropogenic materials — particularly iron-rich residues — as additives in metallurgical charges supports both resource efficiency and environmentally responsible waste management. This study examines the formation of metallurgical pellets incorporating 50 % red mud, a by-product of alumina production. The formulation was optimized to ensure mechanical integrity and reducing capacity, with high-moor peat employed as both a binder and a reducing agent for Fe₂O₃. Thermal treatment at 560 °C resulted in the formation of magnetic phases, including magnetite and maghemite, enabling subsequent magnetic separation to recover an iron-rich concentrate suitable for inclusion in standard metallurgical feedstocks. The influence of pellet granulometry post-thermal treatment on magnetic separation efficiency was evaluated across a range of magnetic field strengths. Optimal processing conditions were established, yielding a non-magnetic fraction comprising 19.4 % of the total mass. These findings confirm the feasibility of low-temperature thermal treatment of peat–sludge pellets, followed by magnetic separation, to produce a viable intermediate material for use in direct iron reduction processes.
This work was supported by the International Competence Centre in Mining Engineering Education under the auspices of UNESCO as part of the «Science» project (St. Petersburg, Russian Federation).

1. Pelevin A. E. Iron ore beneficiation technologies in Russia and ways to improve their efficiency. Zapiski Gornogo Instituta. 2022. Vol. 256. pp. 579–592.
2. Brichkin V. N., Kurtenkov R. V., Maksimova R. I, Bormotov I. S. Regeneration and recycling of lime component in complex processing of kaolin raw materials. Obogashchenie Rud. 2024. No. 4. pp. 32–38.
3. Trushko V. L., Utkov V. A., Bazhin V. Yu. Topicality and possibilities for complete processing of red mud of aluminous production. Zapiski Gornogo Instituta. 2017. Vol. 227. pp. 547–553.
4. Petkova A. P., Gorbatyuk S. M., Sharafutdinova G. R., et al. Selection of materials and technologies for the electrochemical synthesis of sodium ferrate. Metallurgist. 2024. Vol. 68. pp. 449–459.
5. Eldeeb A. B., Brichkin V. N., Kurtenkov R. V., Bormotov I. S. Study of the peculiarities of the leaching process for self-crumbling limestone-kaolin cakes. Obogashchenie Rud. 2021. No. 2. pp. 27–32.
6. Brichkin V. N., Vasiliev V. V., Bormotov I. S., Maksimova R. I. Production and recycling of limes in integrated mineral processing. Gornyi Zhurnal. 2021. No. 11. pp. 88–94.
7. Xue S.-G., Wu Yu., Li Yi-W., et al. Industrial wastes applications for alkalinity regulation in bauxite residue: A comprehensive review. Journal of Central South University. 2019. Vol. 26, Iss. 2. pp. 268–288.
8. Khalifa A. A., Bazhin V. Yu., Ustinova Ya. V., Shalabi M. E. Study of the kinetics of the process of producing pellets from red mud in a hydrogen flow. Zapiski Gornogo Instituta. 2022. Vol. 254. pp. 261–270.
9. Income from waste: Russian scientists propose a way to process red mud. Nauchnaya Rossiya. 2021. URL: https://scientificrussia.ru/articles/dohody-iz-othodov-rossijskieuchenye-predlozhili-sposob-pererabotki-krasnogo-shlama (accessed: 13.12.2024).

10. Dmitriev A. The comprehensive utilisation of red mud utilisation in blast furnace. Recovery and utilization of metallurgical solid waste. IntechOpen, 2019. 13 p. DOI: 10.5772/intechopen.80087
11. On the state and use of the mineral resources of the Russian Federation in 2022. State Report. Moscow: VIMS, 2023. 640 p.
12. Lebedeva A. A., Bogomolov V. A. The Russian iron ore market in 2017 – 1 months 2024. Promyshlennik Sibiri. 2024. No. 1. pp. 26–28.
13. Lebedev A. B., Noah H. L., Martines Kh. Ya., Balandinsky D. A. The influence of a mixture of nepheline, red mud and calcinated coke on the strength of iron ore pellets. Chernye Metally. 2024. No. 7. pp. 10–18.
14. Aleksandrova T. N. Сomplex and deep processing of mineral raw materials of natural and technogenic origin: state and prospects. Zapiski Gornogo Instituta. 2022. Vol. 256. pp. 503–504.
15. Pyagay I. N., Kremcheev E. A., Pasechnik L. A., Yatsenko S. P. Carbonization processing of bauxite residue as an alternative rare metal recovery process. Tsvetnye Metally. 2020. No. 10. pp. 56–63.
16. Jayasankar K., Ray P. K., Chaubey A. K., et al. Production of pig iron from red mud waste fines using thermal plasma technology. International Journal of Minerals, Metallurgy and Materials. 2012. Vol. 19. pp. 679–684.
17. Zinoveev D. V., Grudinskii P. I., Dyubanov V. G., Kovalenko L. V., Leont′ev L. I. Global recycling experience of red mud – A review. Part I: Pyrometallurgical methods. Izvestiya Vuzov. Chernaya Metallurgiya. 2018. Vol. 61, No. 11. pp. 843–858.
18. Gräfe M., Power G., Klauber С. Bauxite residue issues: III. Alkalinity and associated chemistry. Hydrometallurgy. 2011. Vol. 108, Iss. 1–2. pp. 60–79.
19. Lebedev A. B., Utkov V. A. Chemical interactions of red mud during the cleaning of an industrial gases ejected to the atmosphere from harmful impurities. Russian Metallurgy (Metally). 2020. Vol. 2020. pp. 1653–1657.
20. Agatzini-Leonardou S., Oustadakis P., Tsakiridis P. E., Markopoulos C. Titanium leaching from red mud by diluted sulfuric acid at atmospheric pressure. Journal of Hazardous Materials. 2008. Vol. 157, Iss. 2–3. pp. 579–586.
21. Bibanaeva S. A., Skachkov V. M., Sabirzyanov N. A., Lebedeva E. M., Koryukov V. N., Ufimtsev V. M. Effect of calcium-containing additions on the extraction of alumina from the red mud of alumina production. Rasplavy. 2019. No. 1. pp. 99–102.
22. Korneev V. I., Suss A. G., Tsekhovoy A. I. Red mud. Properties, storage, application. Moscow: Metallurgiya, 1991. 144 p.
23. Tanutrov I. N., Sviridova M. N., Savenya A. N. New process of joint processing of technogenic waste. Izvestiya Vuzov. Tsvetnaya Metallurgiya. 2013. No. 1. pp. 21–26.
24. Gebler I. V., Smolyaninov S. I. Fuel and smelting materials based on peat. Izvestiya Tomskogo Politekhnicheskogo Universiteta. Inzhiniring Georesursov. 1964. Vol. 126. pp. 8–11.
25. Liu X., Han Yu., He F., Gao P., Yuan Sh. Characteristic, hazard and iron recovery technology of red mud – A critical review. Journal of Hazardous Materials. 2021. Vol. 420. DOI: 10.1016/j.jhazmat.2021.126542
26. Zhang Q., Sun Yo., Hun Yu., et al. Review on coalbased reduction and magnetic separation for refractory ironbearing resources. International Journal of Minerals, Metallurgy and Materials. 2022. Vol. 29. pp. 2087– 2105.
27. Chun T. J., Zhu D. Q., Pan J., He Z. Preparation of metallic iron powder from red mud by sodium salt roasting and magnetic separation. Canadian Metallurgical Quarterly. 2014. Vol. 53, Iss. 2. pp. 183–189.
28. Rao M., Zhuang J., Li G., Zeng J., Jiang T. Iron recovery from red mud by reduction roasting magnetic separation. Light metals. Springer Cham, 2013. pp. 125–130.
29. Li G., Liu M., Rao M., et al. Stepwise extraction of valuable components from red mud based on reductive roasting with sodium salts. Journal of Hazardous Materials. 2014. Vol. 280. pp. 774 – 780.
30. Archambo M. S., Kawatra S. K. Red mud: Fundamentals and new avenues for utilization. Mineral Processing and Extractive Metallurgy Review. 2020. Vol. 42, Iss. 2. pp. 1–24.
31. Pat. 2120456 Russian Federation.
32. Pat. 2326519 Russian Federation.
33. Mikhaylov A. V., Bazhin V. Yu., Piiraynen V. Yu. Analysis of prospects of thermal conversion of peat raw materials and their use in ferrous metallurgy. Chernye Metally. 2024. No. 9. pp. 9–14.
34. Mikhailov A. V. Coal-peat compositions for co-combustion in local boilers. Zapiski Gornogo Instituta. 2016. Vol. 220. pp. 538–544.
35. Lobas O. P., Smolyaninov S. I. Investigation of thermal decomposition of peat and the reducibility of iron ore by the method of derivatography. Izvestiya Tomskogo Politekhnicheskogo Universiteta. Inzhiniring Georesursov. 1973. Vol. 235. pp. 26–28.
36. Vyatkin G. P., Senin A. V., Digonsky S. V., Mikhailov G. G. On iron oxide reduction thermodynamics in the FeO–C–H system. Alternativnaya Energetika i Ekologiya. 2011. No. 11. pp. 29–31.
37. Krutilin A. N., Kukharchuk M. N., Sycheva O. A. Solidphase reduction of iron oxides by carbon. Lit'yo i Metallurgiya. 2012. No. 2. pp. 11–16.
38. Demidov A. I., Markelov I. A. Phase transitions and their thermodynamic properties in the iron-oxygen system. Nauchno-tekhnicheskie Vedomosti SPbPU. Estestvennye i Inzhenernye Nauki. 2017. Vol. 23, No. 4. pp. 127–131.
39. Piirainen V. Yu., Mikhailov A. V., Barinkov V. M., Starovoitov V. N. The use of sludge-peat composition for the processing of alumina production waste. Obogashchenie Rud. 2022. No. 6. pp. 51–58.