Composition, structure, and thermal behavior of three gasification coarse slag samples based on Zhundong...

To achieve resource utilization of gasification coarse slag, this study selected three coarse slag samples based on Zhundong coal from different types of gasifiers (CS-SH (from Texaco gasifier), CS-YK (from Opposed four-nozzles gasifier), and CS-TY (from Jinhua gasifier)). Composition and structure characteristics of the three slags were systematically analyzed by XRD, SEM, FT-IR, Raman, XPS, and N₂-adsorption desorption methods. Thermal weight loss kinetics parameters under different atmospheres were fitted using the Coats-Redfern model. Results indicate significant property differences among the three slags due to the variations in gasification processes. CS-SH exhibits a "carbon-coated ash" core-shell structure, shows higher contents of fixed carbon (42.31%) and surface carbon (80.20%), and presents a porous flocculent network, with a micropore proportion of 90.95% and specific surface area of 153.23 m² g^-1, making it suitable for use as an adsorption raw material and a co-combustion fuel. CS-YK has the characteristics of medium-calcium fly ash, with activation energies of 44.18 kJ mol^-1 (n = 3) and 110.21 kJ mol^-1 (n = 1) for thermal cracking and combustion, and lower comprehensive combustion index, demonstrating the potential of a building material precursor. CS-TY, with ash content of 93.3%, displays an "ash-coated carbon" structure, where dense inorganic layers inhibit gasification and combustion reactivity, which meets low-calcium fly ash standards and is suitable for high-temperature-resistant building materials. Notably, the SiO₂/Al₂O₃ ratio of CS-TY reaches 2.5, providing a new route for molecular sieve synthesis.