Home – Home – Jornals – Chemistry for Sustainable Development 2025 number 6

A detailed study of high-temperature solid-phase transformations occurring in dispersed microspheres smaller than 10 mm in size (d_m = 3 mm and d₉₉ = 10 mm) belonging to the suspended matter (PM₁₀) of fly ash from the combustion of hard coal from the Ekibastuz and Kuznetsk coal basins has been carried out within the synthesis of glass-ceramics materials. It has been established for PM₁₀ microspheres of macrocomponent composition SiO₂-Al₂O₃-FeO isolated as narrow fractions from fly ash from the combustion of Ekibastuz coal that there is an increase in the content of mullite phase (from 17 to 31 wt%), cristobalite phase is formed (up to 29 wt%); the content of glass phase decreases from 65 to 25 wt%. In the samples of narrow fractions of PM10 microspheres from fly ashes from Kuznetsk coal combustion, crystallisation of the glass phase at 1100 °C leads to a noticeable increase in the concentration of mullite phase (from 3 to 17 wt%), the formation of cristobalite and anorthite phases (3 and 6 wt%, respectively); the amount of glass phase decreases from 93 to 70 wt%. A well-consolidated composite with low porosity (0.4 %), insignificant water absorption (0.2 %), and high strength (56 MPa) was obtained using the direct sintering method based on dispersed microspheres of PM₁₀ fly ash from the combustion of Kuznetsk coal. On the basis of dispersed microspheres of PM₁₀ fly ash from the combustion of Ekibastuz coal, high-porous (open porosity 44-52 %) composites with the homogeneous microporous structure, strength 20-36 MPa, liquid permeability up to 478 L/(m2⋅h⋅bar) and the dispersed microimpurities retention ratio of 0.98-0.99 were obtained. The acid resistance of the obtained glass-ceramic materials is 97-100 %.