RECONDITIONING METHOD OF MOLDING SAND BY FLUIDIZED ROASTING FURNACE

摘要

PURPOSE:To minimize fuel consumption by controlling the oxygen content of fluidizing air so that a natural roasting condition is started without frequent start-stop operations of a burner. CONSTITUTION:Molding sand (a) is charged into a furnace up to a prescribed level from a hopper 105 and the charging is stopped. Blasting is started to form a fluidized bed 111 by the molding sand a' in the part below the roasting section 103 above a nozzle 108. The burner 106 is ignited to heat abd roast the sand a' forming the bed 111. The burner 106 is stopped at the point of the time when the bed 111 is heated up to the roasting temp. A takeout port 107 is opened and at the same time, the charging of the sand (a) is restarted. A flow regulating valve 112 is opened to replenish oxygen through an oxygen replenishing pipe 113 and to increase the oxygen contained in the fluidizing air from the nozzle 108. The inside of the bed 111 attains a high oxygen atmosphere state, by which the combustion of the combustible material of the binder contained in the molding sand is accelerated. The temp. of the bed 111 shows an increasing tendency even if the burner 106 is stopped. The quantity of the oxygen is decreased by the valve 112 when the bed 111 attains the prescribed temp.