Abstract: It is an object of the present invention to provide a technique for solving the following problem by properly controlling the flow of gas such as air (oxidizing gas): a problem that the degree of reduction cannot be increased due to the air entering a feedstock-feeding zone or a discharging zone. The technique is a method for producing reduced iron. The method includes a feedstock-feeding step of feeding a feedstock containing a carbonaceous reductant and an iron oxide-containing material into a rotary hearth furnace, a heating/reducing step of heating the feedstock to reduce iron oxide contained in the feedstock into reduced iron, a melting step of melting the reduced iron, a cooling step of cooling the molten reduced iron, and a discharging step of discharging the cooled reduced iron, these steps being performed in that order in the direction that a hearth is moved.

Abstract: Metallic iron nuggets made by reducing-melt of a material containing a carbonaceous reductant and a metal-oxide-containing material, the metallic iron nuggets comprising at least 94% by mass, hereinafter denoted as “%”, of Fe and 1.0 to 4.5% of C, and having a diameter of 1 to 30 mm are disclosed.

Abstract: The amounts of a CaO-containing substance, an MgO-containing substance, and a SiO2-containing substance, contained in a raw material mixture, are adjusted such that manufacturing operation is performed with the slag basicity (CaO+MgO)/SiO2 of 1.3 to 2.3, and with MgO-concentration of 5 to 13% by mass as to the slag composition, which are dependent upon the concentration of each of CaO, MgO, and SiO2, contained in the raw material mixture. This provides a manufacturing method for high-quality granulated metallic iron with low sulfur concentration, wherein a raw material mixture containing an iron-oxide-containing substance such as iron ore and a carbonaceous reducing agent such as a carbon material are subjected to reducing and melting with a moving hearth-type reducing furnace while suppressing sulfur concentration as much as possible, generated in the granulated metallic iron, particularly due to the carbon material such as coal.

Abstract: An object of the present invention is to provide a method for producing metallic iron, in which after a mixture including a carbonaceous reducing agent and iron oxide is fed onto a hearth of a moving hearth reducing-melting furnace and is then heated so that the iron oxide is reduced and melted, metallic iron to be obtained is cooled and is then discharged outside the furnace for recovery. In the method described above, even when powdered metallic iron is squeezed into the surface of the hearth, or the hearth is damaged by slag infiltration and corrosion, the removal and repair can be easily performed, the operation rate and maintenability of the hearth can be improved, and hence a long continuous operation can be suitably performed.

Abstract: Metallic iron nuggets made by reducing-melt of a material containing a carbonaceous reductant and a metal-oxide-containing material, the metallic iron nuggets comprising at least 94% by mass, hereinafter denoted as “%”, of Fe and 1.0 to 4.5% of C, and having a diameter of 1 to 30 mm are disclosed.

Abstract: The present invention is intended to provide a method for producing metallic iron, which comprises the steps of supplying a mixture containing a carbonous reducing agent and iron oxides onto a hearth of a reduction melting furnace of the moving hearth type, heating the mixture for reduction melting of the iron oxides, cooling thus-obtained metallic iron, and discharging the metallic iron to the outside of the furnace for recovery. The method can easily remove or repair the surface of a hearth even when metallic iron powder is buried in the hearth surface or even when the hearth surface suffers from slag infiltration and erosion, can increase an availability factor and maintainability of the hearth, and is suitably practiced for long-term continuous operation.

Abstract: The present invention is intended to provide a method for accelerating separation of granular metallic iron as an objective product and slag as a by-product when the granular metallic iron is produced with reduction melting of raw-material agglomerates that contain an iron-oxide containing material and a carbonous reducing agent, thereby producing metallic iron of a high iron grade in which slag is satisfactorily separated and removed.

Abstract: A method for making metal nuggets comprises heating a material containing a metal-oxide-containing substance and a carbonaceous reductant to reduce metal oxide in the material and then further heating the produced metal so as to melt the metal while allowing the metal to separate from a by-product slag component and to form granular iron. A cohesion accelerator for the by-product slag is mixed into the material to produce metal nuggets having a high metal purity, a large diameter, and superior transportation and handling qualities at a high yield and high productivity.

Abstract: The present invention provides a sealing mechanism of a feeding device for feeding lumps and/or powder to a moving-hearth heating furnace. The feeding device includes a vibrating feeder having a trough in which a hole for feeding the lumps and/or powder to the furnace is formed and a duct for guiding the lumps and/or powder dropped through the hole to a hearth of the heating furnace. The sealing mechanism includes a water sealing mechanism having a skirt plate, a weir plate, a side surface of the duct, and liquid. The skirt plate is provided on the lower surface of the trough. The weir plate is provided above a ceiling of the heating furnace. The liquid is kept in a tank serving as a pool of liquid which is formed by the side surface of the duct and the weir plate.

Abstract: Metallic iron nuggets made by reducing-melt of a material containing a carbonaceous reductant and a metal-oxide-containing material, the metallic iron nuggets comprising at least 94% by mass, hereinafter denoted as “%”, of Fe and 1.0 to 4.5% of C, and having a diameter of 1 to 30 mm are disclosed.

Abstract: The present invention is directed to a method of producing granular metallic iron, including: heating a formed raw material comprising a carbonaceous reductant and a substance containing iron oxide in a reduction melting furnace to subject the iron oxide contained in the formed raw material to solid-state reduction; and carburizing reduced iron resulting from the solid-state reduction with carbon contained in the carbonaceous in the formed raw material and causing resulting molten metallic iron to coalesce into the granular metallic iron, wherein an atmospheric gas present in proximity to the formed raw material in the carburizing and melting step has a reduction degree of not less than 0.5. The present invention is also directed to a method of producing metallic iron, including forming a deposit layer containing slag produced in the reduction melting process on hearth refractories, thereby protecting the hearth refractories while producing the metallic iron.

Abstract: A method of manufacturing a molten metal iron by charging a starting material at least comprising a carbonaceous reducing material and an iron oxide-containing material into a rotary hearth furnace, reducing under heating the charged starting material into a solid reducing iron, carburizing the metal iron in the solid reduced iron with the carbon ingredient in the carbonaceous reducing material, thereby melting the metal iron, separating the slag ingredient contained in the starting material by the melting, and discharging the molten metal alloy in the molten state as it is to the outside of the rotary hearth furnace for recovery, wherein a downward inclined surface is disposed at an angle 3 to 30° relative to the horizontal plane on the upper surface of a hearth of the rotary hearth furnace on which the starting material is placed, and the molten metal iron is discharged at the discharging position for the molten metal iron from the lowest portion of the inclined surface.

Abstract: The present invention is an apparatus and method for the direct reduction of iron oxide utilizing a rotary hearth furnace to form a high purity carbon-containing iron metal button. The hearth layer may be a refractory or a vitreous hearth layer of iron oxide, carbon, and silica compounds. Additionally, coating materials may be introduced onto the refractory or vitreous hearth layer before iron oxide ore and carbon materials are added, with the coating materials preventing attack of the molten iron on the hearth layer. The coating materials may include compounds of carbon, iron oxide, silicon oxide, magnesium oxide, and/or aluminum oxide. The coating materials may be placed as a solid or a slurry on the hearth layer and heated, which provides a protective layer onto which the iron oxide ores and carbon materials are placed. The iron oxide is reduced and forms molten globules of high purity iron and residual carbon, which remain separate from the hearth layer.

Abstract: The present invention is an apparatus and method for the direct reduction of iron oxide utilizing a rotary hearth furnace to form a high purity carbon-containing iron metal button. The hearth layer may be a refractory or a vitreous hearth layer of iron oxide, carbon, and silica compounds. Additionally, coating materials may be introduced onto the refractory or vitreous hearth layer before iron oxide ore and carbon materials are added, with the coating materials preventing attack of the molten iron on the hearth layer. The coating materials may include compounds of carbon, iron oxide, silicon oxide, magnesium oxide, and/or aluminum oxide. The coating materials may be placed as a solid or a slurry on the hearth layer and heated, which provides a protective layer onto which the iron oxide ores and carbon materials are placed. The iron oxide is reduced and forms molten globules of high purity iron and residual carbon, which remain separate from the hearth layer.

Abstract: The present invention is directed to a method of producing granular metallic iron, including: heating a formed raw material comprising a carbonaceous reductant and a substance containing iron oxide in a reduction melting furnace to subject the iron oxide contained in the formed raw material to solid-state reduction; and carburizing reduced iron resulting from the solid-state reduction with carbon contained in the carbonaceous reductant to cause the reduced iron to melt, while separating off gangue components contained in the formed raw material and causing resulting molten metallic iron to coalesce into the granular metallic iron, wherein an atmospheric gas present in proximity to the formed raw material in the carburizing and melting step has a reduction degree of not less than 0.5.

Abstract: A method of manufacturing a molten metal iron by charging a starting material at least comprising a carbonaceous reducing material and an iron oxide-containing material into a rotary hearth furnace, reducing under heating the charged starting material into a solid reducing iron, carburizing the metal iron in the solid reduced iron with the carbon ingredient in the carbonaceous reducing material, thereby melting the metal iron, separating the slag ingredient contained in the starting material by the melting, and discharging the molten metal alloy in the molten state as it is to the outside of the rotary hearth furnace for recovery, wherein a downward inclined surface is disposed at an angle 3 to 30° relative to the horizontal plane on the upper surface of a hearth of the rotary hearth furnace on which the starting material is placed, and the molten metal iron is discharged at the discharging position for the molten metal iron from the lowest portion of the inclined surface.

Abstract: A method for manufacturing reduced iron briquettes, wherein reduced iron obtained by a direct reduction method is made into briquettes using a briquette machine, and whereafter the hot briquettes are subject to gradual cooling at a cooling rate in the range of 150.degree. C. to 250.degree. C. per minute using water spray. The reduced iron briquettes thus obtained are (a) less prone to breakage break during storage and transport; (b) less prone to degeneration into powder accompanying such breakages etc.; and (c) also display an excellent degree of metallization. Hence, the loss in weight during storage and transport can be reduced, and the harmful effects caused by dust to the transport vehicles, ships, loading/unloading equipment, and operators of the same can be reduced. Also, since the number of breakages is reduced, there is also a reduction in the amount of any re-oxidation of the reduced iron which tends to occur at newly exposed faces, whereby a product of more consistent quality can be obtained.

Abstract: Disclosed is a method of manufacturing briquettes of reduced iron, wherein a residual oil on distillation containing petroleum asphalt or petroleum pitch is sprayed on the surfaces of rolls. The petroleum asphalt or petroleum pitch are thermally cracked into hydrocarbon gas and carbon by the heat (650.degree. to 750.degree. C.) of the reduced ion. This makes it possible to prevent briquettes from sticking on roll pockets, and hence to provide stable operation of the briquette manufacturing apparatus.