Saint-Petersburg Mining University, Saint Petersburg, Russia:

V. N. Brichkin, Head of Metallurgy Department, Doctor of Technical Sciences, e-mail: Brichkin_VN@pers.spmi.ru
A. T. Fedorov, Postgraduate Student at the Metallurgy Department, e-mail: s185005@stud.spmi.ru

Presently, one can definitely state a rising interest to potassium-bearing aluminium ores, which is due to a gradual depletion of conventional raw materials and the fact that the ores that are mined today are leaner and have a more complex composition. At the same time, soda-potassium products, potassium fertilizers, aluminium hydroxide, alumina and alumina materials are in high demand and sell at high prices. Today, the focus is on new deposits of urtite rock and nepheline ores, as well as those of ultrapotassium rischorrite and synnyrite rock. That’s why it is very important to have a basic understanding of the nature and properties of the technically important system Na₂O – К₂O – Al₂O₃ – H₂O, which defines the performance of the key processes involved, as well as the output and quality of the final product. In this regard, studying phase equilibria in the above system, the information about which is lacking or inconsistent, can be pointed out as one of the current research priorities. Two methods were tested aimed at reducing the time necessary to reach equilibrium in the Na₂O – K₂O – Al₂O₃ – H₂O system. One involves hydrolytic decomposition of aluminate liquors with aluminium hydroxide used as seed; the other involves a mathematical description of the curves characterizing the kinetics of gibbsite solubility in alkaline liquors with a given mole fraction of K₂O. Similar laboratory equipment and materials were used in the experimental study regardless of the way equilibrium was reached and identified. Through experiments, it was established that the process of approaching equilibrium in predominantly potassium aluminate liquors has complex kinetics and mechanics impeding rapid identification of equilibrium composition of liquors. With regard to the technique that involves gibbsite dissolution in weak sodium-potassium liquors, the authors demonstrate how asymptotic approximation functions can be effectively used to determine maximum solubility of aluminium oxide. The results of experiments aimed at defining the equilibrium compositions of liquors at 60 oC in certain instances of the Na₂O – К₂O – Al₂O₃ – H₂O system have a good and satisfactory correlation with the modelling data based on the additivity principle, which suggests that the modelling technique can effectively be applied to other temperatures and instances of the 4-component system in view.

This research was funded by the Russian Science Foundation under the Agreement No. 18-19-00577-П dated April 28, 2021 on granting funds for basic scientific research and exploratory research.

1. Litvinenko V. S. Digital Economy as a Factor in the Technological Development of the Mineral Sector. Natural Resources Research. 2020. Vol. 29. pp. 1521–1541. DOI: 10.1007/s11053-019-09568-4.
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. 130530.
3. Nurgaliev D. F., Sizyakov V. M., Utkov V. A. Reduction of Alkali Content in Nepheline Sludge for the Production of Heat-Resistant Insulating Materials From it. Refractories and Industrial Ceramics. 2019. No. 60. pp. 174–176.
4. Alekseev A. I. Building closed process circuits for comprehensive processing of apatite-nepheline ores. Journal of Mining Institute. 2015. Vol. 215. pp. 75–83.
5. Sizyakov V. M. Sintering of alkali aluminosilicates and hydrochemical processing of cakes: Process regularities. Journal of Mining Institute. 2016. Vol. 217. pp. 102–112.
6. Siziakova E., Ivanov P. On the mechanism of silica transition into alumina solutions in the leaching of nepheline sinters. Materials Science Forum. 2021. Vol. 1031. pp. 190–195.
7. Dubovikov О. A., Sundurov A. V. Leaching kinetics for thermally activated bauxite. Obogashchenie Rud. 2021. No. 4. pp. 34–39. DOI: 10.17580/or.2021.04.06.
8. Layner A. I. Alumina production. Moscow : Gosudarstvennoe nauchno-tekhnicheskoe izdatelstvo literatury po chernoy i tsvetnoy metallurgii, 1961. 619 p.
9. Xie Yanli, Zhao Qun, Lu Zhenan, Bi Shiwen. Study on the effect of K₂O on seed precipitation in sodium aluminate liquors. Light Metals. 2006. pp. 159–163.
10. Xie Yanli, Zhao Qun, Lu Zhenan, Bi Shiwen. Study on negative effect of K₂O on precipitation of gibbsite. Light Metals. 2005. pp. 219–222.
11. Teslya V. G., Volokhov Yu. A., Sizyakov V. M. Effect of ions in sodium and potassium aluminate liquors on aluminium hydroxide precipitation kinetics. Zhurnal prikladnoy khimii. 1984. No. 591. pp. 534–539.
12. Anikeev V. I., Ananieva N. N., Kotlyagin E. G., Eremeev D. N. Crystallization of aluminium hydroxide during decomposition of the aluminate liquor resultant from nepheline processing. Tsvetnaya metallurgiya. 2003. No. 3. pp. 27–31.
13. Lebedev A. B., Utkov V. A., Khalifa A. A. Sintered sorbent utilization for H₂S removal from industrial flue gas in the process of smelter slag granulation. Journal of Mining Institute. 2019. Vol. 237. pp. 292–297.
14. Kozyrev B. A., Sizyakov V. M. Heap leaching of red mud by the formiate method. Obogashchenie Rud. 2021. No. 4. pp. 40–45. DOI: 10.17580/or.2021.04.07.
15. Alekseev A. I., Kononchuk O. O., Goncharova M. V., Hippmann S. et al. Recovery of CaCO3 from the Nepheline Sludge of Alumina Production. Chemie-Ingenieur-Technik. 2019. No. 4. pp. 1–9.
16. 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. DOI: 10.17580/tsm.2020.10.08.
17. Suss A. G., Damaskin A. A., Senyuta A. S., Panov A. V. et al. The influence of the mineral composition of low grade aluminum ores on aluminium extraction by acid leaching. Light Metals. 2014. pp. 105–109.
18. Siziakova E. V., Ivanov P. V., Boikov A. V. Application of calcium hydrocarboaluminate for the production of coarse-graded alumina. Journal of Chemical Technology and Metallurgy. 2019. Vol. 54. pp. 200–203.
19. Bazhin V. Yu., Glazev M. V. Refractory materials of metallurgical furnaces with the addition of silicon production waste. Non-ferrous Metals. 2022. No 1. pp. 32–39. DOI: 10.17580/nfm.2022.01.05.
20. Rimkevich V. S., Pushkin A. A., Girenko I. V. Complex processing of alkaline aluminosilicates by the fluorideammonium method. Obogashchenie Rud. 2020. No. 4. pp. 27–34. DOI: 10.17580/or.2020.04.05.
21. Gorbunova Ye. S., Zakharov V. I., Alishkin А. R. All-round chemicaldressing technology for processing of rischorrites. Obogashchenie Rud. 2011. No. 4. pp. 12–16.
22. Kozyreva L. V., Korobeynikov A. N., Menshikov Yu. P. A new kind of ultrapotassium rock in the Khibiny Mountains. Recent mineralogical discoveries in the Karelian-Kola Region. Petrozavodsk : Izdatelstvo KarNTs AN SSSR, 1990. pp. 116–129.
23. Antropova I. G., Alekseeva E. N., Budaeva A. D., Dorzhieva O. U. Thermochemical concentration of ultra-potassium aluminosilicate raw materials (synnyrite) using magnesium-containing additives of natural origin. Obogashchenie Rud. 2018. No. 6. pp. 14–19. DOI: 10.17580/or.2018.06.03.
24. Xi Ma, Jing Yang, Hongwen Ma, Changjiang Liu. Hydrothermal extraction of potassium from potassic quartz syenite and preparation of aluminum hydroxide. International Journal of Mineral Processing. 2016. Vol. 147. pp. 10–17.
25. Shuangqing Su, Hongwen Ma, Xiuyun Chuan, Biya Cai. Preparation of potassium sulfate and zeolite NaA from K-feldspar by a novel hydrothermal process. International Journal of Mineral Processing. 2016. Vol. 155. pp. 130–135.
26. Chizhikov D. M., Kitler I. N., Layner Yu. A. Solubility isotherms of the К₂O – Аl₂O₃ – Н₂O system. Proceedings of the Third All-Union Meeting on Alumina Chemistry and Technology. Erevan : NTI SNKh, 1964. pp. 333–342.
27. Agranovskiy A. A., Berkh V. I., Kavina V. A. et al. A metallurgist’s handbook on non-ferrous metals. Alumina production. Moscow : Metallurgiya, 1970. 320 p.
28. Sipos P., Schibeci M., Peintler G., Maya P. M. et al. Chemical speciation in concentrated alkaline aluminate solutions in sodium, potassium and caesium media. Interpretation of the unusual variations of the observed hydroxide activity. The Royal Society of Chemistry. 2006. pp. 1858–1866.
29. Brichkin V. N., Fedorov A. T. Thermodynamic Modelling of Ion Equilibria in the Na₂O – Al₂O₃ – H₂O System with Gibbsite. Tsvetnye Metally. 2022. No. 3. pp. 74–81. DOI: 10.17580/tsm.2022.03.08.
30. Fricke R., Jucaitis P. Untersuchungen uber die Gleichgewichte in den Systemen Al₂O₃ – Na₂O – H₂O und Al₂O₃ – K₂O – H₂O. Zeitschrift fur anorganische und allgemeine Chemie. 1930. Vol. 191. pp. 129–149.
31. Mengjie Luo, Junxiang Ye, Jin Xue, Chenglin Liu et al. Phase equilibrium in the ternary system K₂O – Al₂O₃ – H₂O at 323.15, 333.15, 343.15, and 353.15 K. Journal of Chemical & Engineering Data. 2020. DOI: 10.1021/acs.jced.0c00017.
32. Rosenberg S. P., Healy S. J. A thermodynamic model for gibbsite solubility in Bayer liquors. 4^th International Alumina Quality Workshop, Darwin. 1996. pp. 301–310.
33. Golubev V. O., Chistiakov D. G., Brichkin V. N., Litvinova T. E. Systems and aids mathematical modeling of the alumina refinery methods: problems and solutions. Non-ferrous Metals. 2019. No. 1. pp. 40–47. DOI: 10.17580/nfm.2019.01.07.
34. Golubev V. O., Litvinova T. E. Dynamic simulation of industrial-scale gibbsite crystallization circuit. Journal of Mining Institute. 2021. Vol. 247. pp. 88–101.
35. Abramowitz M., Stegun I. A. et al. Handbook of mathematical functions with formulas, graphs, and mathematical tables, 9^th printing. New York : Dover, 1972. 881 p.
36. Morgunov A. P., Derkach V. V. Fitting of experimental efficiency and reliability curves. Omsk : Omskiy gosudarstvennyi tekhnicheskiy universitet, 2017. 52 p.