Baikal Institute of Nature Management SB RAS (Ulan-Ude, Russia):
Antropova I. G., Head of Laboratory, Candidate of Engineering Sciences, inan@binm.ru
Khomoksonova D. P., Junior Researcher, darkhom@mail.ru

The paper outlines the specific concentration and processing features of refractory high-potassium aluminosilicate raw materials using the example of synnyrites and potassium feldspars. Synnyrite is an ultrapotassic rock (18–21 wt. % K₂O), mainly composed of potassium feldspars (70–80 wt. %) and kalsilite (20–30 wt. %). The paper considers various deep processing scenarios for potassium aluminosilicate rocks based on alkaline and acidic methods with preliminary thermochemical or hydrochemical activation. It is shown that the nepheline method is ineffective for the processing of synnyrites due to an increase in limestone consumption, higher silica values in the raw material (over 50 wt. %) and, consequently, excessive solid waste generation. A combined technology based on sulfuric acid leaching with preliminary thermochemical activation of the original ore in the presence of magnesite or dolomite may be recommended as a promising technology for the complex processing of synnyrite. This approach reduces the sintering costs, recovers the magnesium additives consumed in the form of an additional finished product (magnesium sulfate hexahydrate MgSO₄·6H₂O), and minimizes waste generation. Two options have been proposed for processing synnyrite into final products: the traditional approach with the output of alumina Al₂O₃ and potassium sulfate K2SO4, and a new approach, allowing, for the first time, to produce the more scarce aluminium magnesium spinel MgAl2O4 and potassium magnesium sulfate K₂Mg(SO₄)₂. The new processing method for the aluminium potassium sulphates KAl(SO₄)₂ obtained envisages their solid-phase interaction with potash K₂CO₃ and brucite Mg(OH)₂ (or MgO) to form MgAl2O₄ and K₂Mg(SO₄)₂.

1. Arkhangelskaya V. V. Deposits of synnyrites of Russia. Razvedka i Okhrana Nedr. 2014. No. 6. pp. 20–24.
2. Wang Zhao, Zhang Quanyou, Yao Ying, Yongzhong Jia, Xie Bingjun. The extraction of potassium from K-feldspar ore by low temperature molten salt method. Chinese Journal of Chemical Engineering. 2018. Vol. 26, Iss. 4. pp. 845–851.
3. Ciceri D., Close T. C., Barker A. V., Allanore A. Fertilizing properties of potassium feldspar altered hydrothermally. Communication in Soil Science and Plant Analysis. 2019. No. 50. pp. 482–491.
4. Arsentyev V. A., Gerasimov A. M., Mezenin A. O. Kaolines beneficiation technology study with application of hydrothermal modification. Obogashchenie Rud. 2017. No. 2. pp. 3–9. DOI: 10.17580/or.2017.02.01.
5. Brichkin V. N., Kurtenkov R. V., Eldib A. B., Bormotov I. S. State and development options for the raw materials base of aluminum in non-bauxite regions. Obogashchenie Rud. 2019. No. 4. pp. 31–37. DOI: 10.17580/or.2019.04.06.
6. Potassium on the global market: 68 million tons belong to potassium chloride, and 7 million tons belong to potassium sulfate. URL: https://agrotrade.club/news/view/s/kalij-naglobalnom-rynke-68-mln-tonn-prinadlezit-kaliu-hloristomua-7-mln-tonn-sulfatu-kalia (accessed: 20.09.2021).
7. Ciceri D., Oliveira M., Allanore A. Potassium fertilizer via hydrothermal alteration of K-feldspar ore. Green Chemistry. 2017. No. 19. pp. 5187–5202.
8. Aman S. A., Danzig S. Ya., Dzikovich K. A. at al. Nepheline-kalsilite rocks of Siberia as a complex aluminaagrochemical raw materials. Tsvetnye Metally. 1988. No. 1. pp. 4–43.
9. Danzig S. Ya., Andreeva E. D., Pivovarov V. V. et al. Nepheline rocks are complex aluminum raw materials. Moscow: Nedra, 1988. 190 p.
10. Aman S. A., Danzig S. Ya., Pivovarov V. V., Tikhonov N. N. Assessment of industrial use of nepheline ores. Nonferrous Metallurgy. 1991. No. 7. pp. 6–11.
11. Ponomarev V. D., Sazhin V. S., Ni L. P. Hydrochemical alkaline method of processing aluminosilicates. Moscow: Metallurgy, 1964. 105 p.
12. 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.
13. 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.
14. Lü Li, Chun Li, Zhang Guoquan, Hu Xiaowei, Liang Bin. Decomposition behavior of CaSO4 during potassium extraction from a potash feldspar-CaSO₄ binary system by calcinations. Chinese Journal of Chemical Engineering. 2018. Vol. 26. pp. 838–844.
15. Pat. 2372290 Russian Federation.
16. Matveev V. A., Mayorov D. V., Brichkin V. N., Gorbunova E. S. Khibiny rischorrite is a promising raw materials for producing potassium fertilizers, alumina and other products. Gorny Informatsionno-analiticheskiy Byulleten'. 2015. No. 19 (Special Issue). pp. 146–152.
17. Gorbunova E. S., Zakharov V. I., Alishkin А. R. All-round chemical-dressing technology for processing of rischorrites. Obogashchenie Rud. 2011. No. 4. pp. 12–16.
18. Nikiforov K. A., Khanturgaeva G. I., Gulyashinov A. N. Nonequilibrium processes in the technology of mineral raw materials processing. Novosibirsk: Nauka, 2002. pp. 26–27.
19. Author's certificate 1421693 USSR.
20. Author's certificate 1761671 USSR.
21. Antropova I. G., Alekseeva E. N., Budaeva A. D. Integrated processing method for synnyrite with production of alumina and potassium sulfate. Journal of Mining Science. 2019. Vol. 55, No. 6. pp. 1007–1012.
22. Pat. 2749824 Russian Federation.
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. Shcherbakova T. A., Shevelev A. I. Magnesite raw material base of Russia and prospects of its development. Georesursy. 2016. Vol. 18, No. 1. pp. 75–78.
25. Fedorov V. P. Geological conditions of the localization and formation of the quality of magnesites in the Larginsko-Kaktolginsky region: dis. abstract for the degree of Candidate of Geological and Mineralogical Sciences. Chita, ChitaSTU, 2003. 24 p.