煤矸石钠化焙烧反应机理与过程调控研究OA

[Purposes]To enhance the recovery efficiency of valuable metals from coal gangue,in this study,the mechanism and process regulation of sodium roasting are investigated with Na2CO3 as an activator within the temperature range of 200-900℃.[Methods]The phase transformation behav-ior and structural evolution during roasting were systematically characterized by SEM,FTIR,XRD,XPS,and TG-DSC analyses.[Results]Results indicate that 800℃is the optimal roasting tempera-ture,at which the dense lamellar structure of coal gangue transforms into a porous amorphous mor-phology and crystalline nepheline(NaAlSiO4)can be formed.The coordination environment of alumi-num changes from octahedral[AlO6]to tetrahedral[AlO4],leading to enhanced reactivity.Kinetic analysis based on the Kissinger model reveals an apparent activation energy of 52.91 kJ·mol-1 for the main reaction stage.Thermodynamic calculations by using HSC Chemistry and FactSage show that the reaction SiO2+NaAlO2→NaAlSiO4 exhibits negative Gibbs free energy across the entire tempera-ture range,indicating its spontaneous behavior.At 800℃,the Gibbs free energy reaches equilibrium,consistenting with the experimental results.This study elucidates the structural evolution and thermo-dynamic stability mechanism of sodium-roasted coal gangue,providing theoretical guidance for the ef-ficient metals extraction and resources utilization of high-alumina solid wastes.