Chemical Composition of Ash in Ulug-Khem Coal

Abstract

The chemical composition and properties of coal ash from the Kaa-Khem (GZh), Mezhegey (Zh), and Elegest (Zh) fields in the Ulug-Khem Basin are compared in order to develop recommendations for the use of such coal. Elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and X-ray fluorescent spectroscopy are used to study the organic and mineral components of the coal and to determine the main ash components (SiO₂, Al₂O₃, Fe₂O₃, CaO, etc.). In accordance with State Standard GOST 11022–95, the ash content of the coal is determined at 815 ± 10°C. The fusibility characteristics (softening point and melting point), the slag viscosity, and the slagging and fouling are calculated. It is found that the ash from the Kaa-Khem coal (39% SiO₂, 14% Al₂O₃, 21% Fe₂O₃, and 12% CaO) is very thermostable (t_so = 1154.6°C). The ash from the Mezhegey coal (10% SiO₂, 8% Al₂O₃, 36% Fe₂O₃, and 24% CaO) is of elevated basicity (I_b = 3.83), with a low melting point (1105.2°C). The ash from the Elegest coal (32% SiO₂, 19% Al₂O₃, 23% Fe₂O₃, and 14% CaO) has a balanced composition, with moderate slag viscosity. Thus, the samples with high melting point (Kaa-Khem and Elegest coal) have little risk of slagging, whereas the Mezhegey coal requires additional measures to decrease the fouling (R_f = 3.28). The results confirm that Tuvinian coal is promising for practical use, if the specifics of the ash are taken into account.