An improved vortex inhibitor 20 for separating slag from molten metal during the discharge of molten metal through a nozzle 14 includes a generally uniform castable refractory body 22 having a generally hemispherical or hemi-ellipsoid shape having a plurality of generally triangular shaped projection elements 30, 32, 34, 36, 38 and 40) defining a plurality of generally constant dimension grooves 42, 44, 46, 48, 50 and 52 extending downward from the top side 26 toward an apex 41 of the vortex inhibitor 20.