An electric arc melting furnace includes a furnace shell (1) with an electrode (3) for melting scrap by heat of arc, an air blasting port (20) for blasting air, oxygen or oxygen-enriched air into the furnace shell (1) through an air control valve (19), a carbon blasted quantity indicator (CI) for measuring quantity of carbon to be charged into the furnace shell (1), a scrap charged quantity indicator (SI) for measuring quantity of the scrap charged into the furnace shell (1), an oxygen blasted quantity indicator (OI) for measuring quantity of oxygen blasted into the furnace shell (1) and an arithmetic processor (7) for computing quantity of air required for complete combustion of carbon monoxide (23) in the furnace shell (1) in response to measured value from the indicators (CI)(SI)(OI) to control a degree of opening of the air control valve (19). Air with quantity in proportion to the carbon monoxide (23) is blasted through the air blasting port (20), which enables control of combustion temperature in the furnace shell (1) and control of temperature in the scrap preheating device.
Method and device to feed tuyeres in an electric furnace, the tuyeres comprising a central conduit to deliver a comburent gaseous substance and a peripheral conduit to deliver a cooling gaseous substance, the method providing to send to the central conduit a comburent mixture consisting of oxygen and neutral gas (N.sub.2, Ar, etc.) in defined percentages, the oxygen and the neutral gas being fed, for each of the tuyeres, to a mixing device with a high mixing capacity, at least the pressure of the neutral gas being able to be adjusted on the relative feed line so as to modulate the pressure of the mixture according to the characteristics of the melting process.
The present invention provides an arc-melting apparatus, which attains extremely high efficiency by preheating scraps using exhaust gas from the melting chamber. The arc-melting apparatus needs for no device to carry and supply an iron source to a melting chamber, which makes it possible to preheat the next charge. The arc-melting apparatus has a melting furnace which melts scraps, a preheating shaft connected directly to an upper part of one side of the melting furnace, an arc electrode for melting scraps in the melting furnace, a bucket for supplying scraps to the preheat shaft so as to continuously maintain scraps in the melting furnace and in the preheating shaft, a tapping portion having a tapping hole, being projected outward from the melting furnace and a tilting device for tilting the melting furnace on a side of the tapping portion. The tapping portion is arranged at an orthogonal direction to the direction of the supplied cold iron source. The preheating shaft of the melting furnace and the tapping portion have a distance between the mutual part, so that scraps do not flow out on a the tapping hole side.
The present invention provides an arc-melting apparatus which attains extremely high efficiency by preheating scraps using exhaust gas from the melting chamber. The arc-melting apparatus needs for no device to carry and supply an iron source to a melting chamber, which makes it possible to preheat the next charge. The arc-melting apparatus has a melting furnace which melts scraps, a preheating shaft connected directly to an upper part of one side of the melting furnace, an arc electrode for melting scraps in the melting furnace, a bucket for supplying scraps to the preheat shaft so as to continuously maintain scraps in the melting furnace and in the preheating shaft, a tapping portion having a tapping hole, being projected outward from the melting furnace and a tilting device for tilting the melting furnace on a side of the tapping portion. The tapping portion is arranged at an orthogonal direction to the direction of the supplied cold iron source. The preheating shaft of the melting furnace and the tapping portion have a distance between the mutual part, so that scraps do not flow out on a the tapping hole side.
