Abstract: A hot coke bed is established at the bottom of a vertical shaft furnace, e.g. an iron melting cupola. The cupola is then charged with alternate layers of ferrous metal and coke material, respectively. Burners burn hydrocarbon fuel in the presence of a stoichiometric excess of oxygen-enriched air and thus form a hot gas mixture including oxygen. The hot gas mixture passes upwards through the shaft of the cupola thereby providing sufficient heat to melt the ferrous metal. Molten ferrous metal flows downwards under gravity into and through the coke bed and may be removed through a tap hole. At least one jet of oxygen is injected into the hot coke bed so as to maintain it at a temperature sufficient to superheat the molten metal. Preferably a fan is operated to dilute with air the combustion gases above the level of the charge in the shaft and thereby create secondary flames. No air blast is supplied to the cupola.

Abstract: A hot coke bed is established at the bottom of a vertical shaft furnace, e.g. an iron melting cupola. The cupola is then charged with alternate layers of ferrous metal and coke material, respectively. Burners burn hydrocarbon fuel in the presence of a stoichiometric excess of oxygen-enriched air and thus form a hot gas mixture including oxygen. The hot gas mixture passes upwards through the shaft of the cupola thereby providing sufficient heat to melt the ferrous metal. Molten ferrous metal flows downwards under gravity into and through the coke bed and may be removed through a tap hole. At least one jet of oxygen is injected into the hot coke bed so as to maintain it at a temperature sufficient to superheat the molten metal. Preferably a fan is operated to dilute with air the combustion gases above the level of the charge in the shaft and thereby create secondary flames. No air blast is supplied to the cupola.