Study of the Phase Composition of a Ceramic Sample Based on Ferrodust and Clay at Different Annealing Temperatures

A ceramic sample obtained from the wastes of oil shale (intershale clay) and iron industry (ferrodust from the self-decaying cinder slag of low-carbon ferrochromium) without using any conventional natural materials has been studied. Ferrodust from self-decaying slags is the most representative waste of iron industry with an increased content of calcium oxide (CaO > 40%). The phase transformations were studied on the samples with a composition of 70% intershale clay and 30% ferrodust. The study showed that at an annealing temperature of the samples of 950°C, the carbonates CaCO 3 experienced the thermal decomposition, forming hematite, wollastonite, and diopside, and a liquid phase appeared. When the annealing temperature increased to 1000°C, cristobalite and anorthite formed in the samples, and the content of the liquid phase (glass phase) increased. At an annealing temperature of 1050°C, there were no significant changes except an increase in the cristobalite and anorthite contents. Further increase in the annealing temperature to 1100°C led to higher glass content, which improves the physicomechanical properties of the samples. At 1100°C the contents of anorthite, diopside, and cristobalite increased, while the hematite content decreased, and field spar disappeared, probably transforming into glass.