Abstract: A stir plug of frusto-conical shape for introducing gas into a mass of molten metal and comprising a plug having an outer core formed of a first refractory material. A wear indicator in the form of a central core comprised of a second refractory material is located within a centrally located recess in the outer core adjacent the bottom end of the plug. The central core extends from the bottom end of the plug towards the top end of the plug and is of a predetermined height less than that of the outer core. The upper end of the central core when exposed by the erosion of the stirring plug provides a visual indication of when that plug should be replaced.

Abstract: A stirring plug for introducing gas into a mass of molten metal and a method of making the plug. The plug is of a generally frusto-conical shape having a central axis and includes plural elongated slots formed of generally smooth walls extending between the top and bottom ends of the plug and arranged in a frustum array. Each of the slots has a predetermined cross sectional area in any plane perpendicular to the central axis. The method comprises providing a member having a hollow frusto-conical shape cavity and inserting plural wax coated steel tapes or plastic tapes in a frustom array therein. The cavity is then filled with a refractory castable mix and it is allow to air set to form a frusto-conical body. That body is then heated to an elevated temperature to form a dense ceramic plug. In the case of the plastic tapes the heating of the mix causes the tapes to melt or sublime to form the slots.

Abstract: An improvement in a slide gate for a container holding molten metal comprising a slide housing and refractory bodies made of a refractory composition, which refractory bodies have been impregnated with carbon-containing media, the improvement residing in employing as the carbon-containing medium an oil containing less than 10% by weight pitch.