A method of purifying steel in a tundish, especially to remove alumina inclusions, comprises passing the steel through at least one refractory board having apertures through it and introducing inert gas into the steel at the upstream side of the foot of the board to cause a stream of bubbles to flow over the upstream side of the board. One of the boards may comprise a ceramic filter element. The boards may be non-vertical and have integral gas supply means. The apertures may taper, may have axes angled from perpendicular to the board's plane and may have high alumina content surfaces. The upstream side of the board may have an exothermic layer.
Dimples can be produced in the surfaces of cast ceramic pieces by casting these pieces in a mold which contains as the dimple producing pattern a layer of bubble pack. In another embodiment of the invention, there is described the mold which incorporates bubble pack to produce dimpled effects in cast ceramic pieces.
Molten steel in tundishes can be contacted with high surface area ceramic shapes which remove the alumina and other impurities contained in steel. Certain ceramic shapes, in particular tundish baffles, having a large surface area which acts as alumina traps for molten steel contained in tundishes are also disclosed.
Molten steel in tundishes can be contacted with high surface area ceramic shapes which remove the alumina and other impurities contained in steel. Certain ceramic shapes, in particular tundish baffles, having a large surface area which acts as alumina traps for molten steel contained in tundishes are also disclosed.
The filtration of molten ferrous metal is accomplished by providing a porous ceramic filter preferably comprising particles of alumina and partially stabilized zirconia that are spaced by interconnected cells to form circuitous and tortuous pathways throughout the ceramic body. The filter is a disc-like structure that can have different surface configurations such as corrugations or a waffle design. The filter can be flat-surfaced with an array of cylindrical openings or counterboard openings extending completely through the filter, or with openings extending partially into the filter from the upper and lower sides of the filter. Several relatively thin filters can be arranged in tandem, if desired.
