Viscosity of High-Iron Slags from Australian Coals

There is a need to characterize slag flow properties for continuous operation of entrained flow gasifiers at the expected slag tapping temperature range. Slag flow characteristics include the slag phase composition, slag viscosity, and temperature of critical viscosity (TCV). Previous studies of viscosity behavior and viscosity modeling for slags from Australian coal ashes include compositions with up to 15 wt % FeO. This work investigates phase compositions and viscosity behavior of high-iron slags (16.5–21 wt % FeO) from Australian coal ashes, their blends, and fluxed mixtures. The investigated slag compositions are selected from mullite, spinel, and anorthite (feldspar) primary phase fields. A series of viscosity measurements were made over the range of 1200–1600 °C using laboratory-produced slags, and TCV and viscosity contours are presented. The viscosity results are also modeled by a modified Urbain treatment, and two separate sets of polynomial coefficients are generated for evaluating viscosities as a function of the temperature and slag composition.