Influence of CaO and Fe2O on the surface tension and structure of SiO2-Al2O3-CaO-Fe2O3-MgO synthetic slags

The surface tension of coal slags influences the adhesion between the slag and furnace walls in slagging gasifiers, which further influences the efficiency, maintenance cost and reliability of the gasifier. The influence of CaO and Fe2O3 on the surface tension and structure of synthetic slags were investigated. The results indicate that the surface tension linearly increases with the increase of CaO content in the synthetic slag. When Fe2O3 exceeds 3.8 mole%, the surface tension of synthetic slag increases slowly with the increase of Fe2O3, which is related to Fe2O3 acting as an intermediate oxide. The degree of polymerization and the electrostatic potential of ions are related to a variation in surface tension, and the number of unsatisfied bonds increases because the Si-O-Si network structure was depolymerized. Here, NBO/T cannot reflect the degree of depolymerization of slag due to the variation in intermediate Fe2O3 contents.