PURPOSE: To increase melting capacity and to obtain desired molten metal for castings easily by melting a thermit compsn. for castings consisting of Al, iron oxide, scrap iron, etc. in a refractory reacting vessel, charging the same into an electric furnace and subjecting the molten metal to heat insulating and controlling of components.

CONSTITUTION: Powder 5 of a thermit compsn. for castings consisting of 10W 20% Al, 32W70% iron oxide, 8W50% scrap ion, etc. is prepared. A suitable iron plate 10 is placed on the outflow nozzle 4 of a refractory reacting vessel 3, and the powder 5 is packed therein. The vessel 3 is installed on an electric furnace 6. Desired control element groups 7 are beforehand put in the bottom part of the furnace 6. The powder 5 is fired by a suitable means and is melted by thermit reaction by which slag 9 is separated in the upper layer part and molten metal 8 in the lower layer part. The plate 10 is melted by the heat of the metal 8 and drops together with the metal 8 into the furnace 6. Electricity is conducted to the furnace 6 to insulate the heat of the metal 8 or heat the same and to control the components thereof; thereafter the molten metal is tapped.