METHOD OF CONTROLLING INTERNAL DIAMETER OF RUNNER IN GROOVE TYPE INDUCTION HEATING DEVICE

PROBLEM TO BE SOLVED: To provide a method of controlling an internal diameter of a runner in a groove type induction heating device capable of stably operating an induction furnace provided with the groove type induction heating device by stabilizing the internal diameter of the runner by controlling the deposition of alumina to an inner face of the runner. SOLUTION: In the method of controlling the internal diameter of the runner in the groove type induction heating device disposed in the induction furnace storing molten iron, and having the runner formed by using a magnesite refractory, in the case that electric conductivity in starting the use of the groove type induction heating device is 100%, a concentration of metallic aluminum in molten iron is adjusted to be 0.0009 mass% or higher when a conductance ratio indicating the change of electric conductivity accompanied by the use of the groove type induction heating device is on a rising trend or over a prescribed value within a range of >100% and ≤140%, and the concentration of metallic aluminum in the molten iron is adjusted to be 0, or higher than 0 and lower than 0.0009 mass% when it is on a falling trend or lower than a prescribed value within a range of 65-85%. COPYRIGHT: (C)2010,JPO&INPIT