Thise work analyzes phase transformations in quaternary mixtures (clay–glass–hematite–waste activated sludge (WAS)), processed at 800–1000 °C under conditions of oxygen deficiency. The results of the study showed that, depending on the temperature treatment of mixtures of different compositions, the processes of carbon formation from WAS, carbon participation in reductive processes, and phase transformations in silicate subsystems occur simultaneously. After Ttr = 800 °C the main phases are fayalite and quartz, additional phases are wollastonite and feldspars. After Ttr = 900 °C the main phases are fayalite, quartz, wollastonite, and the additional phases are feldspars. After Ttr = 1000 °C the main phases are wollastonite, iron, quartz, additional phases are hematite, fayalite.
Parra et al. (Thu,) studied this question.