Synthesis of Plate-Like Alumina via Synergistic Activation from Co-Combustion Ash of Coal Gangue and Corn Stalk
This study reports a streamlined route for synthesizing plate-like α-Al2O3 via co-combustion activation of coal gangue and corn stalk, enabling high-value utilization of solid wastes. The introduction of corn stalk significantly reduces the apparent activation energy of coal gangue combustion and increases the acid leaching yield of aluminum to 81.9%. Mechanism analysis reveals that titanium and iron ions in the co-combustion ash leachate act as natural morphology regulators, facilitating the formation of a plate-like structure in the alumina product, with titanium exhibiting leaching behavior consistent with that of aluminum. Furthermore, a high content of AlO6 structural units in the precursor effectively promotes the direct conversion into dense α-Al2O3 crystals during thermal treatment, thereby enhancing product density. Under optimized conditions (800 °C, 1 h), the as-prepared α-Al2O3 exhibits a plate-like morphology, with a median particle size (d50) of 5.70 μm and a density of 4.94 g/cm3. This work provides a new approach for the synergistic resource utilization of coal gangue and biomass waste.