Centrifugal atomizer has been widely used to produce metal powders, slag granules through dry slag granulation process. In this process, liquid is poured at the center of the spinning disc, which disintegrates to form droplets, and becomes solid granules/powders on cooling. In this study, a numerical simulation has been carried out to estimate powder size considering phase change into the model, and the obtained results are validated with experimental measurements. Different mechanisms of powder production viz., direct powder formation, ligament to powder formation, and film to powder formation have been captured at various liquid flow rates and angular disc speed. The effect of composition of the model liquid slag and its properties like viscosity, density, surface tension, etc. has been studied using this mathematical model. Further, the effect of superheat on solidification was also considered. Finally, powder size distribution has been correlated with properties of the slag, superheat of the liquid, and process variables. Graphical Abstract: [Figure not available: see fulltext.] © 2021, The Minerals, Metals & Materials Society.