Baikal Institute of Nature Management, Siberian Branch of the Russian Academy of Sciences (Ulan-Ude, Russia):

Antropova I. G., Head of Laboratory, Candidate of Engineering Sciences, inan@binm.ru
Alekseeva E. N., Leading Engineer, styazhkina82@inbox.ru
Budaeva A. D., Junior Researcher, abud@binm.ru

Buryat State University (Ulan-Ude, Russia):
Dorzhieva O. U., Master's Student, styazhkina82@inbox.ru

This paper outlines the results of the thermochemical concentration studies of highly resistant high-potassium aluminosilicate raw materials (synnyrites) from the Kalumny section of the Synnyrsky alkaline massif, producing kalsilite-leucite concentrate. It is shown that the main mineral constituents of synnyrites are microcline and orthoclase from the potassium feldspar group (64.2%) with the general chemical formula of K[AlSi₃O₈] and the K[AlSiO₄] kalsilite, a potassium variety of nepheline (23.6%). Based on the study of the composition, physical and chemical properties of synnyrite and thermodynamic evaluation of the interactions of K[AlSi₃O₈] and K[AlSiO₄] with CaMg(CO₃)₂ and Mg(OH)₂, the method of selecting low-cost magnesium-containing compounds of natural origin to be used as raw material additives in thermochemical decomposition of the main acid-resistant minerals of the source raw material was substantiated. The process parameters of synnyrite sintering with the use of each of the additives were established, ensuring the maximum decomposition of potassium feldspar to the easily liberated form of the K[AlSi₂O₆] leucite. It is shown that the final calcium-and magnesium-containing phases of the sintered material are akermanite (Ca₂Mg(Si₂O₇)) in the case of sintering with dolomite and forsterite (Mg₂SiO₄) when sintering with brucite. The method developed enables reducing the costs of the thermochemical processes required to ensure complete decomposition of synnyrite into the kalsilite-leucite concentrate suitable for further acid treatment. In addition, due to the high content of active potassium, the artificial kalsilite-leucite concentrates formed may be recommended for use as chlorine-free potassium-containing complex fertilizers.
The study was carried out within the framework of the UMNIK grant (project No. 46649/2017).

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