Kobe Steel, Ltd.

Kabushiki Kaisha Kobe Seiko Sho

Midrex Technologies, Inc.

Tsuyoshi Mimura

Takao Harada

Koji Tokuda

Hiroshi Sugitatsu

Tomio Suzuki

Masataka Tateishi

Hideaki Fujimoto

Akihide Hikosaka

Takeo Yoshigae

Shingo Yoshida

Shoichi Kikuchi

Shuzo Ito

Haruyasu Michishita

Itsuo Miyahara

Tetsushi Deura

Sei Kimura

Kiminori Hajika

Hitoshi Nakata

Yukimasa Iwamoto

Shuzo Itoh

Katsuma Fujiwara

Takashi Miyake

Tomoaki Omoto

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

Provided is a technique for increasing the yield of reduced iron, thereby improving productivity when manufacturing reduced iron by heating an agglomerate. This method for manufacturing reduced iron includes: a step in which a mixture is agglomerated, said mixture containing an iron oxide-containing substance, a carbonaceous reducing agent, and a melting point regulator; and a step in which reduced iron is manufactured by heating the obtained agglomerate, reducing and partially melting the iron oxide in the agglomerate, and aggregating the iron component. The particle size of the fine particulate iron generated in the step in which the reduced iron is manufactured is adjusted, and the fine particulate iron is blended into the mixture.

Method for producing reduced iron

A steel wire rod is obtained, in which a gas flow rate during gas stirring in molten steel treatment is controlled to be 0.0005 Nm/min to 0.004 Nm/min per molten steel of 1 ton, thereby the rod satisfies a specified composition, and oxide base inclusions in any section including an axis line of the steel wire rod satisfy the following composition X, the inclusions having width of 2 &#x3bc;m or more perpendicular to a rolling direction, wherein the number of the oxide base inclusions of the following composition A is 1 to 20, and the number of the oxide base inclusions of the following composition B is less than 1: In the steel wire rod, drawability and fatigue properties are improved to the utmost.

Steel wire rod having excellent drawability and fatigue properties, and manufacturing method of the same

A method of continuously casting molten steel to produce high surface quality slab by preventing depressions and cracking. The steel is high Al steel having an Al content of 0.1% or more. High-Al molten steel is continuously cast using mold powder containing T&#x2014;CaO (T&#x2014;CaO presumes total Ca converted to CaO): 35 to 55%, SiO: 10 to 30%, AlO: 4.0% or less (excluding 0%), MgO: 0.2 to 1.0%, LiO: 7 to 13%, F: 7 to 13%, C: 10.5 to 14%, and inevitable impurities; and satisfying: 1.6&#x2266;[T&#x2014;CaO]/[SiO]&#x2266;5 and 0.2&#x2266;[LiO]/[SiO]&#x2266;1.1. The method is performed by controlling the molten steel surface level fluctuation speed in the mold; the pouring angle of the molten steel in the width direction of the mold; the stroke in the amplitude; and the negative strip time tN as defined.

Method of continuous casting of high-aluminum steel and mold powder

A process for producing molten iron is a process in which while an inert gas is blown into a molten iron layer in an iron bath type melting furnace through bottom-blown tuyeres provided in a hearth bottom thereof to stir the molten iron layer, a carbon material, an additive flux, and solid reduced iron obtained by heating reduction of carbon composite iron oxide briquettes are charged into the above melting furnace, and top blowing of an oxygen-containing gas is performed through a top-blown lance provided for the melting furnace, so that the solid reduced iron is melted by combustion heat obtained by combusting the carbon material and/or carbon in molten iron to form molten iron.

Process for producing molten iron

A method for manufacturing molten iron comprises charging a carbonaceous material, a flux, and solid reduced iron obtained by thermally reducing carbon composite iron oxide agglomerates into an arc melting furnace and melting the solid reduced iron using arc heating in the melting furnace while an inert gas is blown into a molten iron layer from a bottom blowing tuyere on a bottom of the melting furnace, wherein: a carbonaceous material suspending slag layer is formed in an upper portion of a slag layer formed on the molten iron layer when the solid reduced iron is melted into the molten iron; a carbonaceous material coating layer having the carbonaceous material is formed on the carbonaceous material suspending slag layer; and the molten iron and the slag stored in the melting furnace are tapped from a tap hole formed in a lower portion of a furnace wall of the melting furnace.

Method for manufacturing molten iron

Described herein is a smelting reduction process for smelting and reducing an iron oxide material by introducing same into a smelting reduction furnace together with a solid carbonaceous material, a fluxing agent and an oxygen-containing gas, process comprising: subjecting part or all of the solid carbonaceous material to primary combustion using an oxygen-containing gas with an oxygen content corresponding to a theoretical air ratio of 0.4 to 0.9: separating the resulting reducing gas from combustion residue of the solid carbonaceous material; and introducing the reducing gas into a smelting reduction furnace to effect secondary combustion with supply of a separately introduced oxygen-containing gas for smelting and reducing said iron material.

Smelting reduction process using reducing gas generated in precombustor

Described herein is a process for melting iron material in the production of molten iron, in which cold iron material such as scraps, cold pig iron or reduced iron is charged into a melting furnace, the process comprising: feeding a carbon-containing solid material into a precombustion vessel for primary combustion therein with supply of an oxygen-containing gas with an oxygen content corresponding to 0.4 to 0.9 of theoretical air ratio; separating combustion residues of the carbon-containing solid material from the resulting hot reducing gas; and introducing the reducing gas into the melting furnace for secondary combustion therein with supply of an oxygen-containing gas holding an oxygen concentration corresponding to 0.7 to 1.3 of theoretical air ratio in total with the oxygen-containing gas supplied to the precombustion furnace.

Growing community of inventors

Kakogawa, Japan

Tsuyoshi Mimura