Abstract: An exhaust gas duct apparatus for use in a rotary-hearth furnace for heating a starting material including a carbonaceous reducing material and an iron-oxide containing material to produce reduced iron or granular metallic iron. In an exhaust gas duct for use in the rotary-hearth furnace, a cooling part for cooling an exhaust gas discharged from the rotary-hearth furnace to solidify a metal salt in the exhaust gas, a collision part for allowing the exhaust gas just after being cooled to collide therewith to drop down the metal salt solidified, and a direction change duct for guiding the exhaust gas after being collided, in a direction other than a direction of dropping the metal salt, are arranged in this order in two stages.

Abstract: The present invention provides a method for producing a granular metallic iron in which an adhesion inhibitor leveler, an agglomerate leveler, a discharger, and the physical state of materials present on the hearth are optimized to thereby enable agglomerate to be spread in a single layer. The agglomerate hence is evenly heat-treated to enable high-quality granular metallic iron to be produced in satisfactory yield.

Abstract: Not only the cracking of granular reduced iron materials is reduced, but also reduced iron materials are fed uniformly onto a furnace floor regardless of a width of the furnace floor. A feeding system for reduced iron material includes a plurality of material feeding equipments 4 provided in a furnace width direction of a mobile furnace floor type reduction melting furnace, wherein each of the material feeding equipments 4 is constructed by a hopper 10 configured to receive reduced iron materials and discharge the materials from a discharge port 10a, a trough 14 configured to connect the discharge port 10a and a material charging portion of the mobile furnace floor type reduction melting furnace configured to receive the reduced iron materials discharged from the discharge port 10a, an exit portion provided on an exit side of the trough 14, and a vibration applying unit configured to cause the trough to vibrate along a furnace floor moving direction.

Abstract: An exhaust gas duct apparatus for use in a rotary-hearth furnace for heating a starting material including a carbonaceous reducing material and an iron-oxide containing material to produce reduced iron or granular metallic iron. In an exhaust gas duct for use in the rotary-hearth furnace, a cooling part for cooling an exhaust gas discharged from the rotary-hearth furnace to solidify a metal salt in the exhaust gas, a collision part for allowing the exhaust gas just after being cooled to collide therewith to drop down the metal salt solidified, and a direction change duct for guiding the exhaust gas after being collided, in a direction other than a direction of dropping the metal salt, are arranged in this order in two stages.

Abstract: Not only the cracking of granular reduced iron materials is reduced, but also reduced iron materials are fed uniformly onto a furnace floor regardless of a width of the furnace floor. A feeding system for reduced iron material includes a plurality of material feeding equipments 4 provided in a furnace width direction of a mobile furnace floor type reduction melting furnace, wherein each of the material feeding equipments 4 is constructed by a hopper 10 configured to receive reduced iron materials and discharge the materials from a discharge port 10a, a trough 14 configured to connect the discharge port 10a and a material charging portion of the mobile furnace floor type reduction melting furnace configured to receive the reduced iron materials discharged from the discharge port 10a, an exit portion provided on an exit side of the trough 14, and a vibration applying unit configured to cause the trough to vibrate along a furnace floor moving direction.

Abstract: A device for producing granular metal iron by placing a mass of a raw material mixture comprising a substance containing iron oxide and a carbonaceous reducing agent onto a heath of a moving heath type heating furnace and heating the mass to reduce iron oxide in the mass, thereby producing the granular metal iron. The device comprises, in addition to the moving heath type heating furnace, a sieving machine, a first magnetic separator and a second magnetic separator, and also comprises a passage through which a discharged substance from the moving heath type heating furnace is supplied to the sieving machine, a passage through which crude granules that have been sieved by the sieving machine are supplied to the first magnetic separator, and a passage through which fine granules that have been sieved by the sieving machine are supplied to the second magnetic separator.

Abstract: The present invention provides a method for producing a granular metallic iron in which an adhesion inhibitor leveler, an agglomerate leveler, a discharger, and the physical state of materials present on the hearth are optimized to thereby enable agglomerate to be spread in a single layer. The agglomerate hence is evenly heat-treated to enable high-quality granular metallic iron to be produced in satisfactory yield.

Abstract: A process for producing a molten steel (G) is disclosed in which particulate metallic iron can be more efficiently melted. The process includes the step of melting, in an electric arc furnace (2), all charge for iron which comprises: particulate metallic iron (A) produced by a method including a step in which a feed material comprising a carbonaceous reducing material and an iron oxide-containing substance is heated in a rotary hearth furnace (1) as a reducing/melting furnace and the iron oxide contained in the feed material is thereby reduced in the solid state to yield metallic iron and a step in which the resultant metallic iron is heated to a higher temperature to melt the metallic iron and the molten iron is aggregated while separating the iron from the slag (B); and scraps (D) which are another feed material for iron. The process is characterized in that the content of carbon in the particulate metallic iron (A) is regulated to 1.0-4.

Abstract: An object of the present invention is to provide a method for producing granulated metallic iron superior in rust resistance. Another object of the present invention is to provide a method for producing such granulated metallic iron. In the method, the granulated metallic iron is produced by agglomerating a material mixture including an iron-oxide-containing material and a carbonaceous reducing agent; charging and heating the agglomerated material mixture in a moving hearth-type reducing furnace to reduce the iron oxide in the material mixture with the carbonaceous reducing agent to obtain hot granulated metallic iron; and cooling the hot granulated metallic iron, wherein the hot granulated metallic iron is cooled while its relative position is changed; and an oxide coating is formed on the surface of the hot granulated metallic iron by bringing moisture into contact with almost the entire surface of the hot granulated metallic iron.

Abstract: 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 are performed in that order in the direction that a hearth is moved. The furnace includes flow rate-controlling partitions, arranged therein, for controlling the flow of furnace gas and the furnace gas in the cooling step is allowed to flow in the direction of the movement of the hearth with the partitions.

Abstract: A method for producing granular iron comprising: charging agglomerates formed from a raw material mixture containing an iron oxide-containing substance and a carbonaceous reducing agent onto a carbonaceous material spread on a hearth of a furnace; and heating the agglomerates to thereby reduce and melt iron oxides in the agglomerates, wherein the temperature of the agglomerates in the furnace is set in a range between 1200° C. and 1500° C.; the oxygen partial pressure in atmospheric gas under which the agglomerates are heated is set to 2.0×10?13 atm or more at standard state; and the linear speed of the atmospheric gas in the furnace is set to 4.5 cm/second or more.

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: A method for producing metallic iron in which 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. Prior to the feed of raw agglomerates, a granular hearth material is bedded on the moving hearth for forming a layered renewable hearth which can be renewed. Part or the entirety of the renewable hearth which was degraded during operation is renewed, and the hearth material for forming a new renewable hearth is fed. The surface of the newly formed hearth is then leveled and mixture is subsequently fed.

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: A hearth material is laid in the form of a layer on the hearth prior to supply of a mixture containing a carbonaceous reducing agent and iron oxides onto a hearth of a reduction melting furnace, thereby forming a renewable hearth capable of being renewed, and the metallic iron is produced while renewing a part or the whole of the renewable hearth, which has deteriorated during operation, with the hearth material.

Abstract: A method for producing metallic iron in which 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. Prior to the feed of raw agglomerates, a granular hearth material is bedded on the moving hearth for forming a layered renewable hearth which can be renewed. Part or the entirety of the renewable hearth which was degraded during operation is renewed, and the hearth material for forming a new renewable hearth is fed. The surface of the newly formed hearth is then leveled and mixture is subsequently fed.

Abstract: An object of the present invention is to provide a method for producing granulated metallic iron superior in rust resistance. Another object of the present invention is to provide a method for producing such granulated metallic iron. In the method, the granulated metallic iron is produced by agglomerating a material mixture including an iron-oxide-containing material and a carbonaceous reducing agent; charging and heating the agglomerated material mixture in a moving hearth-type reducing furnace to reduce the iron oxide in the material mixture with the carbonaceous reducing agent to obtain hot granulated metallic iron; and cooling the hot granulated metallic iron, wherein the hot granulated metallic iron is cooled while its relative position is changed; and an oxide coating is formed on the surface of the hot granulated metallic iron by bringing moisture into contact with almost the entire surface of the hot granulated metallic iron.

Abstract: A hearth material is laid in the form of a layer on the hearth prior to supply of a mixture containing a carbonaceous reducing agent and iron oxides onto a hearth of a reduction melting furnace, thereby forming a renewable hearth capable of being renewed, and the metallic iron is produced while renewing a part or the whole of the renewable hearth, which has deteriorated during operation, with the hearth material.

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: 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.