St. Petersburg Mining University, St. Petersburg, Russia:

A. B. Lebedev, Cand. Eng., Researcher, Scientific Center "Problems of processing of mineral and technogenic resources", e-mail: 2799957@mail.ru
A. S. Ivkin, Cand. Eng., Head of Laboratory, Scientific Center "Problems of processing of mineral and technogenic resources", e-mail: ivkin.alexey@yandex.ru

Millions of tons of red mud (RM) have accumulated in the dumps of alumina production. Increasing the qualitative and quantitative indicators of sintered ore has become increasingly important in recent years due to the transition from iron production in blast furnaces to direct iron reduction technology. An additive (bentonite) is added to the composition of the pellet to improve the pelletization of the charge. The complete replacement of bentonite with the addition of red mud in the production of sinter is of technical interest. For the study, the following components were used: RM, iron ore concentrate, CaO (analytical grade) and SiO₂ (analytical grade). Previously performed works on the study of polymorphism of dicalcium silicate, associated with the measurement of spontaneous crumbling of the sample during the β → γ transition, were studied. A research method was studied that is sensitive to structural changes during polymorphic transformations, which is represented graphically by dielectric characteristics in a high-frequency field. The mechanism of stabilization of dicalcium silicate with the introduction of red mud into the composition of the sinter charge was studied. It is noted that the RM addition in an amount of 2% doubles the softening interval and accelerates the sintering process when heated in the range from 1150 to 1250 °C. Joint crushing and mixing with limestone were carried out for uniform distribution of the RM additive in the volume of the entire sinter charge. Red mud, taken from the sludge storage of the Ural aluminum plant, is presented with a particle size of less than 270 microns. It has been established that the optimal moisture content of RM supplied to sinter plants is 2–4 %. With the RM addition to 2 %, the temperature of the polymorphic transformation β → γ of the transition of dicalcium silicate contained in the sinter decreases. Acceleration of the sintering process of the charge for the production of pellets is possible with the content of RM up to 2 %, which makes it possible to increase the rate of its sintering up to 20 mm/min, which is 3–5 % higher compared to the charge without RM. In this case, the strength of the pellet does not decrease.

1. Polyakov A., Gorlanov E., Mushihin E. Analytical modeling of current and potential distribution over carbon and low-consumable anodes during aluminum reduction process. Journal of the Electrochemical Society. 2022. Vol. 169. No. 5. DOI: 10.1149/1945-7111/ac6a16
2. Litvinenko V., Bowbriсk I., Naumov I., Zaitseva Z. Global guidelines and requirements for professional competencies of natural resource extraction engineers: Implications for ESG principles and sustainable development goals. Journal of Cleaner Production. 2022. Vol. 338. p. 130530. DOI: 10.1016/j.jclepro.2022.130530
3. Sizyakov V. M., Litvinova T. E., Brichkin V. N., Fedorov A. T. Modern physical and chemical equilibrium description in the system Na₂O–Al₂O₃–H₂O and its analogues. Zapiski Gornogo instituta. 2019. Vol. 237. pp. 298–306. DOI: 10.31897/PMI.2019.3.298
4. Ris А. D., Sundurov A. V., Dubovikov O. A. Behavior of bauxite concentrates during the Bayer leaching stage. Vestnik Irkutskogo gosudarstvennogo tekhnicheskogo universiteta. 2019. Vol. 23. No. 2 (145). pp. 395–403.
5. Kantemirov V. D., Titov R. S., Yakovlev A. M. The main trends in the production of iron ore in Russia. Gornaya promyshlennost. 2018. No. 1 (137). pp. 72–74.
6. Zubkova O., Alexeev A., Polyanskiy A., Karapetyan K., Kononchuk O., Reinmöller M. Complex processing of saponite waste from a diamond-mining enterprise. Applied Sciences. 2021. Vol. 11. No. 14. p. 6615. DOI: 10.3390/app11146615
7. Dmitriev A. M., Korobov N. V., Badalyan A. Zh. Development and research of formation technologies on specialized presses with subsequent sintering of high-density details from iron-based powders. Zapiski Gornogo instituta. 2019. Vol. 236. No. 2. pp. 216–228. DOI: 10.31897/pmi.2019.2.216
8. Khalifa A. A., Bazhin V. Yu., Ustinova Y. V., Shalabi M. E. Kh. 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. DOI: 10.31897/PMI.2022.18
9. Omelchenko I. N., Kuznetsov A. A. New trends in the iron ore market. Gumanitarnyi vestnik. 2017. No. 8 (58). p. 7.
10. Ryabchikov М. Yu., Ryabchikova E. S., Mukhina E. Yu., Cimusev Yu. A. Problems of automatic optimization of fuel consumption control for sintering the sinter charge in order to increase productivity and stabilize the quality of the sinter. Vestnik Samarskogo gosudarstvennogo tekhnicheskogo universiteta. Seriya: Tekhnicheskie nauki. 2017. No. 4 (56). pp. 58–68.
11. Boyarintsev А. V., Aung M. M., Aung H. J., Stepanov S. I. Extraction of aluminum in the complex processing of red mud. Vestnik Voronezhskogo gosudarstvennogo universiteta inzhenernykh tekhnologiy. 2018. Vol. 80. No. 3 (77). pp. 317–322. DOI: 10.20914/2310-1202-2018-3-317-322
12. Maksimov L. I., Mironov V. V. Improving the technology for obtaining highly dispersed powders of metallic iron from the sludge of an iron removal station. Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitelnogo universiteta. 2020. Vol. 22. No. 2. pp. 162–173.
13. Karpova К. S., Karpov A. V. Solid-phase reduction of iron oxides in the laboratory. Sovremennye materialy, tekhnika i tekhnologii. 2018. No. 1 (16). pp. 27–32.
14. Ponomareva M. A., Cheremisina O. V., Mashukova Y. A., Lukyantseva E. S. Increasing the efficiency of rare earth metal recovery from technological solutions during processing of apatite raw materials. Zapiski Gornogo instituta. 2021. Vol. 252. pp. 1–10. DOI: 10.31897/PMI.2021.6.13
15. Krylova S. А., Sysoev V. I., Alekseev D. I., Sergeev D. S., Dudchik I. A. Physico-chemical characteristics of high-magnesian siderites. Vestnik Yuzhno-Uralskogo gosudarstvennogo universiteta. Seriya: Metallurgiya. 2017. Vol. 17. No. 2. pp. 13–21.
16. Singh S., Aswath M. U., Ranganath R. V. Effect of mechanical activation of red mud on the strength of geopolymer binder. Construction and Building Materials. 2018. Vol. 177. pp. 91–101. DOI: 10.1016/j.conbuildmat.2018.05.096
17. Liu S., Guan X., Zhang S., Xu C., Li H., Zhang J. Sintering red mud based imitative ceramic bricks with CO₂ emissions below zero. Materials Letters. 2017. Vol. 191. pp. 222–224. DOI: 10.1016/j.matlet.2016.12.028
18. Lebedev A. B., Musinova P. V. Formation of the strength of pelletized multiphase dicalcium silicate sinter. Chernye Metally. 2022. No. 5. pp. 40–46. DOI: 10.17580/chm.2022.05.07
19. Kuznetsov V. S., Suprun I. K., Petrov D. S. Reduction of dust pollution of the atmosphere during storage of iron ore dressing waste. Moskovskiy ekonomicheskiy zhurnal. 2019. No. 1. pp. 199–206.
20. Archambo M., Kawatra S. K. Red mud: fundamentals and new avenues for utilization. Mineral Processing and Extractive Metallurgy Review. 2021. Vol. 42. No. 7. pp. 427–450. DOI: 10.1080/08827508.2020.1781109
21. Aydin S., Aydin M. E., Beduk F., Ulvi A. Removal of antibiotics from aqueous solution by using magnetic Fe₃O₄/red mud-nanoparticles. Science of The Total Environment. 2019. Vol. 670. pp. 539–546. DOI: 10.1016/j.scitotenv.2019.03.205
22. Boikov A. V., Savelyev R. V., Payor V. A., Erokhina O. O. Evaluation of bulk material behavior control method in technological units using DEM. Part 1. CIS Iron and Steel Review. 2020. Vol. 19. pp. 4–7. DOI: 10.17580/cisisr.2020.01.01
23. Hoang M. D., Do Q. M., Le V. Q. Effect of curing regime on properties of red mud based alkali activated materials. Construction and Building Materials. 2020. Vol. 259. p. 119779. DOI: 10.1016/j.conbuildmat.2020.119779
24. Liu S., Guan X., Zhang S., Dou Z., Feng C., Zhang H., Luo S. Sintered bayer red mud based ceramic bricks: Microstructure evolution and alkalis immobilization mechanism. Ceramics International. 2017. Vol. 43. No. 15. pp. 13004–13008. DOI: 10.1016/j.ceramint.2017.07.036
25. Ortega J. M., Cabeza M., Tenza-Abril A. J., Real Herraiz T., Climent M. Á., Sánchez I. Effects of red mud addition in the microstructure, durability and mechanical performance of cement mortars. Applied Sciences. 2019. Vol. 9. No. 5. p. 984. DOI: 10.3390/app9050984
26. Shiryaeva Е. V., Podgorodetskiy G. S., Malysheva T. Ya., Detkova T. V., Gorbunov V. B. Influence of low-alkaline red mud on the composition and structure of sintering charge from iron ore concentrates of various genesis. Izvestiya vysshikh uchebnykh zavedeniy. Chermaya metallurgiya. 2015. Vol. 57. No. 9. pp. 13–17. DOI: 10.17073/0368-0797-2014-9-13-17
27. Frolov Yu. A., Chukin D. M., Polinov A. A., Emelyanov L. G., Kotyshev V. Ye. Investigation of process of sintering of sinter charge in dense and mechanically loosened layer on sintering machines of sinter plant № 5 of PJSC MMK. Metallurg. 2022. No. 3. pp. 8–12. DOI: 10.52351/00260827_2022_03_8
28. Shao F., Zhuang Y., Ni J., Sheng J., Zhao H., Tao S., Yang K. Comparison of the microstructural characteristics and electrical properties of plasma sprayed Al₂O₃ and Al₂O₃–Ca₂SiO₄ coatings immersed in deionized water. Surface and Coatings Technology. 2021. Vol. 422. p. 127530. DOI: 10.1016/j.surfcoat.2021.127530
29. Agrawal S., Rayapudi V., Dhawan N. Extraction of Iron values from Red mud. Materials Today: Proceedings. 2018. Vol. 5. No. 9. pp. 17064–17072. DOI: 10.1016/j.matpr.2018.04.113
30. Kozyrev B. A., Sizyakov V. M. Heap leaching of red mud by the formate method. Obogashchenie Rud. 2021. No. 4. P. 40–45. DOI: 10.17580/or.2021.04.07
31. Sharikov Yu. V., Sharikov F. Yu., Titov O. V. Optimal control of annealing during the preparation of aluminum hydroxide and cement clinker in tubular rotary kilns. Theoretical Foundations of Chemical Engineering. 2017. Vol. 51. No. 4. pp. 503–507. DOI: 10.1134/S0040579517030125
32. Pyagay I. N., Shaidulina A. A., Konoplin R. R., Artyushevskiy D. I., Gorshneva E. A., Sutyaginsky M. Production of amorphous silicon dioxide derived from aluminum fluoride industrial waste and consideration of the possibility of Its use as Al₂O₃–SiO₂ catalyst supports. Catalysts. 2022. Vol. 12. No. 2. pp. 1–13.
33. Mishra B., Gostu S. Materials sustainability for environment: Red-mud treatment. Frontiers of Chemical Science and Engineering. 2017. Vol. 11. No. 3. pp. 483–496. DOI: 10.1007/s11705-017-1653-z
34. Aleksandrov V. I., Vasilyeva M. A. Hydrotransport of thickened iron ore tailings at the Kachkanar MPP based on the results of pilot tests of the hydrotransport system. Zapiski Gornogo instituta. 2018. Vol. 233. pp. 471–479. DOI: 10.31897/PMI.2018.5.471
35. Kozyrev B. A., Sizyakov V. M., Arsentyev V. A. Principles of rational processing of red mud with the use of carboxylic acids. Non-ferrous Metals. 2022. Vol. 53(2). P. 30–34 DOI: 10.17580/nfm.2022.02.05
36. Gabdulkhakov R. R., Rudko V. A., Pyagay I. N. Methods for modifying needle coke raw materials by introducing additives of various origin (review). Fuel. 2022. Vol. 310. p. 122265. DOI: 10.1016/j.fuel.2021.122265
37. Podgorodetskiy G., Gorbunov V., Panov A., Petrov S., Gorbachev S. Complex additives on the basis of red mud for intensification of iron-ore sintering and pelletizing. Light Metals. 2015. pp. 107–111. DOI: 10.1002/9781119093435.ch20
38. Abe J., Kobayashi Y., Kawase K., Tenjimbayashi M., Shiratori S. Facile synthesis of a high electrical and ion conductivity junction-less 3D carbon sponge electrode for self-standing lithium ion battery anode. RSC Advances. 2018. Vol. 8. No. 12. pp. 6390–6396. DOI: 10.1039/C7RA12759F