Russian Journal of Applied Chemistry. Vol. 96, No. 9, Pages 827-837, 2023

I. P. Kremenetskaya^a^,*, S. N. Ivashevskaya^b, T. K. Ivanova^{a, c}^,**, V. G. Semenov^d, and V. P. Ilyina^b

^aTananaev Institute of Chemistry and Technology of Rare Elements and Mineral Resources, Kola Scientific Center, Russian Academy of Sciences, Apatity, Murmansk oblast, 184209 Russia

^bInstitute of Geology, Karelian Scientific Center, Russian Academy of Sciences, Petrozavodsk, Karelia, 185910 Russia

^cLaboratory of Nature-Like Technologies and Technosphere Safety of the Arctic, Nanomaterials Science Center, Kola Scientific Center, Russian Academy of Sciences, Apatity, Murmansk oblast, 184209 Russia

^dInstitute for Analytical Instrumentation, Russian Academy of Sciences, St. Petersburg, 198103 Russia

Abstract— Virtually unlimited volumes of serpentine resources stimulate search for new procedures for its processing, including those involving thermal activation. Along with the calcination parameters (temperature, time), the crystal-chemical features of the initial serpentines are an important factor. They predetermine the sequence of the formation of new phases in the course of thermolysis and the content of these phases in the heat treatment product. The influence of the calcination temperature on the thermal decomposition of a serpentine mineral, antigorite, was studied by differential scanning calorimetry, X-ray diffraction analysis, and Mössbauer spectroscopy. Amorphous antigorite is not formed in the course of thermolysis, and the intermediate amorphous magnesia–silicate phase is a mixture of two dehydroxylates differing in the ability to react with acid solutions. The activity of the calcination products was determined by two different methods. The optimum calcination temperature is 750°C; it ensures the maximal content of the amorphous active magnesia–silicate phase.

Keywords: serpentine resources, antigorite, magnesium oxide, silicon oxide, differential scanning calorimetry, Mössbauer spectroscopy, active phase content, acid-neutralizing ability, degree of silicon leaching

Structural and Phase Transformations in the Course of Antigorite Thermolysis