An empirical study on the influence of primary particle size distribution of coal gasification slag on its basic physicochemical properties

Abstract

To examine particle-size effects without disturbing the as-formed structure of coal gasification slag (CGS), this work separated raw slag by wet precision sieving into three primary size fractions: <75 μm, 75–150 μm, and >150 μm. The separated fractions were characterized in terms of particle-size distribution, bulk oxides, mineral phases, surface morphology, and pore structure, and the relationships between median primary size and the main physicochemical indices were evaluated. The sieving procedure produced well-bounded fractions, with 75–150 μm representing the largest mass proportion of the raw slag. As the primary size increased, the loss on ignition, residual carbon level, and BET specific surface area decreased, and the amorphous glass phase also declined. In contrast, SiO2, Al2O3, and crystalline-phase proportions rose slightly, whereas CaO and Fe2O3 remained nearly unchanged. These results indicate that primary size records differences in cooling history and carbon retention during gasification. The data provide a basis for size-selective utilization of CGS in cementitious, adsorption, and other resource-oriented applications.