A process and apparatus for the production of intermediate hot metal suitable for further refining into steel is disclosed. The basic process includes the steps of heating a charge of ore in a reducing furnace having a reducing atmosphere therein comprising a mixture of reconditioned and recycled top gas from the reducing furnace and off-gas rich in hydrogen and carbon monoxide produced by a cupola melting unit to reduce the ore to iron, partially carburizing the reduced iron in the reducing furnace with carbon-containing off-gas produced by the cupola melting unit, and melting the reduced and carburized iron together with scrap, slag forming additives and fluxes in a cupola melting unit having a reducing atmosphere therein produced by the combustion of a rich fuel/oxidant mixture to form a molten slag and molten iron suitable for the further refining to produce steel. The process contemplates the further refining of the molten iron from the cupola in an electric steelmaking furnace or an oxygen steelmaking converter. In an alternative form of the process, the reduced and carburized iron is cooled within or outside the reducing furnace to form prereduced metal pellets suitable for use as a part of the burden in a melting unit. The apparatus comprises a refractory lined cupola melting unit portion equipped with burners capable of burning a rich fuel/oxidant mixture to produce a reducing atmosphere within the melting unit and off-gas rich in gaseuos reductants, a direct reducing unit portion communicating with the upper end of the melting unit to receive the melting unit off-gas recirculating and conditioning means to recycle at least a portion of the top gas from the upper region of the reducing unit portion to the lower region of the reducing unit portion, means for introducing ore into the direct reduction unit portion of the apparatus, and means for introducing additives and fluxes into the melting unit portion of the apparatus.
This is disclosed a process of recovering molten pig iron or steel pre-products from lumpy iron-oxide containing charging substances. The charging substances are reduced to sponge iron in a direct reduction zone, the sponge iron is smelted in a meltdown gasifying zone under supply of carbon carriers and oxygen-containing gas forming a coal fluidized bed, and CO and H.sub.2 containing reduction gas is produced, which is injected into the direct reduction zone and reacted there. For the commercial utilization of low-quality scrap grades, such as, e.g., automotive scrap, (a) scrap is charged into the meltdown gasifying zone in addition to sponge iron, (b) the scrap has an apparent weight of between 300 and 1000 kg/m.sup.3, preferably between 400 and 600 kg/m.sup.3, and (c) the temperature of the coal fluidized bed is maintained at 1,500.degree. to 1,700.degree. C., The scrap passes the coal fluidized bed, is carbonized and is smelted by maintaining reducing conditions, and possibly present organic impurities are pyrolyzed.
Process and apparatus for producing ferrous or non-ferrous metals from a charge formed by self-reducing agglomerates (comprising pulverized ores, carbonaceous material plus a binder) consisting the apparatus of a shaft furnace, comprising a cylindrical or conical shaft (3), having, at the top portion thereof, loading gates or devices (1) and an outlet for gases through a chimney (19) or a chamber leading the same to heat regenerators (9) to pre-heat blown-in air and also having one or more rows of tuyeres (15) for blowing air; and a cylindrical or conical hearth (5) having a diameter greater than that of shaft (3) by an amount sufficient for positioning fuel feeders (4) directly over a fuel bed; and on the lower part, one or more rows of tuyeres (13) distributed so as to blow air oxygen enriched or not and injecting or not liquid gaseous, or pulverized fuels, this same apparatus being capable of melting 100% metallic charges of any metal and alloys or different proportions of metallic forms and self-reducing agglomerates.
There is disclosed a process of recovering molten pig iron or steel pre-products from lumpy iron-oxide containing charging substances. The charging substances are reduced to sponge iron in a direct reduction zone, the sponge iron is smelted in a meltdown gasifying zone under supply of carbon carriers and oxygen-containing gas forming a coal fluidized bed, and CO and H.sub.2 containing reduction gas is produced, which is injected into the direct reduction zone and reacted there. For the commercial utilization of low-quality scrap grades, such as, e.g., automotive scrap, (a) scrap is charged into the meltdown gasifying zone in addition to sponge iron, (b) the scrap has an apparent weight of between 300 and 1000 kg/m.sup.3, preferably between 400 and 600 kg/m.sup.3, and (c) the temperature of the coal fluidized bed is maintained at 1,500.degree. to 1,7800.degree. C. The scrap passes the coal fluidized bed, is carbonized and is smelted by maintaining reducing conditions, and possibly present organic impurities are pyrolyzed.
An improved method for operating a blast furnace wherein a portion of the charge is prereduced iron ore with a relatively low metallization in the range of 75% to 90% and a relatively high carbon content in the range of 1.5% to 4.5% by weight. The composition of the sponge iron is selected so as to realize an increase in the production of pig iron and a decrease in the consumption of coke while simultaneously maximizing the over-all economy and efficiency of the blast furnace operation. In a preferred embodiment of the invention at least 80% by weight of the carbon content in the sponge iron used as a portion of the charge to the blast furnace is in the form of ferric carbide.
A process for producing sponge iron by directly reducing particulate, iron-oxide-containing material, wherein reducing gas that is formed from carbon carriers and an oxygen-containing gas in a melt-down gasifying zone is introduced into a reduction zone that contains the iron-oxide-containing material, characterized by the combination of the following characteristic features: (i) to the reduction zone, a reducing gas is fed which contains between iron-oxide-containing material 20 g and 100 g per Nm.sup.3 of a dust having a carbon content of between 30 mass % and 70 mass %; and (ii) the iron-oxide-containing material is exposed to the reducing gas for a time period that exceeds the period for a complete reduction. The process of the invention renders it possible to produce a sponge iron of elevated carbon content.
