Kobe Steel, Ltd.

Midrex International B.v. Zurich Branch

Kabushiki Kaisha Kobe Seiko Sho

Kabushiki Kaisha Kobe Seiko Sho (kobe Steel, Ltd.)

Midrex Technologies, Inc.

Midrex International, B.v., Rotterdam, Zurich Branch

Mesabi Nugget LLC

Koji Tokuda

Shuzo Ito

Shoichi Kikuchi

Isao Kobayashi

Osamu Tsuge

Yasuhiro Tanigaki

Akira Uragami

Keisuke Honda

Sumito Hashimoto

Osamu Tsuchiya

Tsuyoshi Mimura

Itsuo Miyahara

Tomoki Uemura

David C Meissner

Hidetoshi Tanaka

Glenn E Hoffman

Masahiko Tetsumoto

Haruyasu Michishita

Takuya Negami

Noriaki Mizutani

Kyle J Shoop

James C Simmons

Hidekazu Okamoto

Robert F Edgar

Eiichi Ito

Katsuma Fujiwara

According to embodiments, disclosed is a method and system to maintain the soft and sparse slag characteristic favorable for an electric arc to efficiently transfer the energy to molten iron with the power input per furnace area higher than 600 KW/m2 while keeping FeO amount less than 5% in the slag and carbon amount higher than 2.5% in the product hot metal at a DRI melting furnace.

Hot metal production from DRI with electric arc heating

A method includes, in a first furnace, melting 40% to 95% by mass of a solid-state direct reduced iron, and separating a molten pig iron having a carbon content of 2.0% to 5.0% by mass and a temperature of 1350 to 1550° C. and a slag having a basicity of 1.0 to 1.4. In a second furnace, a remainder of the solid-state direct reduced iron is melted together with the molten pig iron separated in the first furnace to form a molten material, and oxygen is blown onto the molten material to decarburize into a molten steel. The solid-state direct reduced iron includes 3.0% by mass or more of SiOand AlOin total and 1.0% by mass or more of carbon. A ratio of a metallic iron to a total iron content contained in the solid-state direct reduced iron is 90% by mass or more.

Method for producing molten steel

A method for producing a molten steel may provide: solid-state direct reduced iron containing 3.0% by mass or more of SiOand AlOin total and 1.0% by mass or more of carbon, a ratio of a metallic iron to a total iron content contained in the solid-state direct reduced iron being 90% by mass or more, and an excess carbon content Cx to the carbon contained in the solid-state direct reduced iron being 0.2% by mass or more. Such methods may include: a slag separation including heating the solid-state direct reduced iron and melting it in an electric furnace without introducing oxygen to separate into a molten steel and a slag, and continuously discharging the slag, and a decarburization including blowing, in the electric furnace, a total amount of oxygen introduced into the electric furnace to the molten steel to decarburize the molten steel after the slag separation.

Molten steel production method

A reduced iron production method includes: a reduction-step of producing reduced iron by heating an agglomerate containing iron oxide and carbonaceous reducing agent to reduce the iron oxide and solidifying a product produced by melting the reduced iron; a first-magnetic-separation-step of separating, among granular metallic iron, first slag, and second slag containing more fine-granular metallic iron than the first slag that are contained in the product, at least the granular metallic iron from the first slag by use of a first magnetic separator to separate first slag containing substance and a granular metallic iron containing substance from each other; a second-magnetic-separation-step of separating the second slag from the first slag containing substance or the granular metallic iron containing substance by use of a second magnetic separator having attraction force different from attraction force of the first magnetic separator; and a crushing-step of crushing the second slag.

Reduced iron production method and production apparatus

A rotary hearth furnace includes: a furnace body which surrounds a ring-like space; a hearth portion which forms a bottom portion of the ring-like space and is rotatable in the rotational direction; a gas exhaust portion which discharges an exhaust gas generated in the ring-like space to the outside of the furnace body; an introducing portion; and a flow rate regulating portion. The introducing portion is disposed upstream of the gas exhaust portion in the rotational direction and introduces a pressure regulating gas into a non-heating section of the ring-like space. The flow rate regulating portion is disposed between the introducing portion and the gas exhaust portion and regulates a flow rate of a gas by adjusting an opening area of the non-heating section.

Rotary hearth furnace, and method for producing reduced iron using rotary hearth furnace

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.

Rotary hearth furnace exhaust gas duct apparatus and method for operating same

A method for manufacturing granular metallic iron by reducing a raw material mixture including an iron oxide-containing material and a carbonaceous reducing agent, comprises: a step of charging the raw material mixture onto a hearth of a moving hearth-type thermal reduction furnace; a step of reducing the iron oxide in the raw material mixture by the carbonaceous reducing agent through the application of heat, thereby forming metallic iron, subsequently melting the metallic iron, and coalescing the molten metallic iron to granular metallic iron while separating the molten metallic iron from subgenerated slag; and a step of cooling the metallic iron to solidify; wherein the heat-reducing step includes a step of controlling the flow velocity of atmospheric gas in a predetermined zone of the furnace within a predetermined range. This method makes it possible to manufacture the granular metallic iron of high quality.

Method and apparatus for manufacturing granular metallic iron

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.

Granulated metallic iron superior in rust resistance and method for producing the same

A high purity of molten iron is produced efficiently at a higher productivity, by feeding a raw material mixture containing a carbonaceous reducing agent, an iron oxide-containing material and a CaO-containing material onto a hearth of a moving-hearth reducing furnace, heat-reducing the raw material mixture in the reducing furnace, and melting it in a melting furnace melting, wherein a blending amount of the CaO-containing material in the raw material mixture is adjusted in such a manner that another feeding of the CaO-containing material into the melting furnace makes a basicity of a slag generated in the melting furnace 1.1 or more an feeding amount of the CaO-containing material becomes 40 kg or less per ton of the molten iron obtained in the melting furnace.

Process for producing molten iron

A rotary hearth furnace includes an exhaust gas eductor. The exhaust gas eductor includes a compartment-defining portion and an exhaust duct. The compartment-defining portion is provided on part of a ceiling of the rotary hearth furnace in an exhaust gas discharge region, and an exhaust duct is connected to the compartment-defining portion. The lower surface of the compartment-defining portion lies higher than the lower surface of the other portion of the ceiling. The compartment-defining portion defines a compartment where the exhaust gas stays. The exhaust duct can include a cooling medium injection nozzle. The furnace increases fuel efficiency by completely burning combustible components remaining in exhaust gas generated in the rotary hearth furnace so as to use the combustible components efficiently for the heating and reduction reaction in the rotary hearth furnace, without problems in producing reduced iron.

Rotary hearth furnace and method of operating the same

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. 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.

Method and apparatus for producing reduced metal

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.

Metallic iron nuggets

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.

Method for producing metallic iron

A method producing metallic iron by reducing raw materials including an iron-oxide containing material and a carbonaceous reducing agent under heating, which can minimize re-oxidization of the metallic iron and can efficiently produce metallic iron having a high metallization ratio and high iron purity at high yield. The method produces metallic iron, by heating raw materials including a carbonaceous reducing agent and an iron-oxide containing material in a reduction melting furnace of the moving hearth type, and reducing and melting iron oxides in the raw materials. The reduction melting furnace is partitioned into at least three zones in a hearth moving direction, at least one partitioned zone upstream in the hearth moving direction is a solid-state reducing zone, at least one downstream partitioned zone is a carburization melting zone, and a reduction aging zone is between the solid-state reducing zone and the carburization melting zone.

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Kobe, Japan

Koji Tokuda