Method of repairing ingot mold bottoms

A method for repairing an eroded bottom of an ingot mold which comprises:

• a. removing the eroded portion of the bottom;
• b. forming a casting space in the mold bottom by cutting a hole through the bottom of the mold, the cross-sectional area of the hole varying such that the diameter of the hole at the inner and outer surfaces of the bottom of the mold are larger than the cross-sectional area of the hole at the interior portion of the mold bottom, the sides of the hole tapering outwardly from the interior portion of the mold bottom towards the inner and outer surfaces of the mold bottom;
• c. cutting one or more notches in a portion of the outwardly tapering side of said hole which is between the point of the hole having the smallest cross-sectional area and the outer surface of the mold bottom;
• d. placing the mold in an upright position on a smooth layer of a compactable refractory material;
• e. providing a protective layer of a refractory material about the inner walls of the mold;
• said layer beginning at the interior entrance of said hole and tapering upwardly and outwardly along the inner walls of the mold;
• f. filling said casting space and a portion of the bottom interior volume of the mold with an alumino-thermic welding material in an amount effective to provide sufficient weld metal to fill said casting space;
• g. igniting said alumino-thermic mixture;
• whereby molten metal is formed from the aluminum thermic reaction and gravitates downwardly into and filling the casting space to form, on cooling, an insert firmly welded and locked into the casting space.