The fusibility and flow properties of Shell gasifier slag were study in this paper.The physical properties of slag were analyzed with X-ray fluorescence

X-ray diffraction

and scanning electron microscopy.The fusion temperature

viscosity and lowestm tapping temperature for slag with the addition of fluxing CaO were measured by using high temperature fusion furnace and high temperature rotational viscometer.The thermodynamic computer package FactSage was used to predict the proportion of solid

the liquidus temperature as well as the mineral phase formed as a function of composition and temperature.The results showed that the fusion temperature

lowest tapping temperature and viscosity of slag in the temperature range of 1400—1500℃ decreased with increasing CaO content

whereas those values increase rapidly with CaO content higher than 35%.The effect of CaO on the liquidus temperature and the solid content at the same temperature calculated by FactSage was similar.The sub-liquidus phase predicted by FactSage transformed from the anorthite phase to the mullite phase with increasing CaO content.Also

the microstructure of quenched slag changed from a loose and porous state to rod-like crystallization.