Kyanite concentrate of the Karabash deposit: Phase transformations during heating

Results are provided for a study of the phase transformation during heating of kyanite concentrates of the Karabash deposit, and the effect of temperature, soaking at the final temperature, and grain size on parameters of kyanite thermal decomposition. IR-spectra for kyanite concentrate of a different degree of transformation, and the microstrcuture of a partially decomposed kyanite grain are given. It is shown that thermal decomposition of kyanite proceeds in the range 1300–1400°C, and linear expansion, temperature for the start and decomposition rate depend on kyanite grain size, and the relaxation of elastic stresses of the kyanite crystal lattice is mainly limited by the decomposition reaction factor.