Abstract: 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 SiO2 and Al2O3 in 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.

Abstract: A method for producing a molten steel may provide: solid-state direct reduced iron containing 3.0% by mass or more of SiO2 and Al2O3 in 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.

Abstract: 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.

Abstract: A method for producing a molten steel may provide: solid-state direct reduced iron containing 3.0% by mass or more of SiO2 and Al2O3 in 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.

Abstract: In a method for producing a molten steel according to one aspect of the present invention, the solid-state direct reduced iron contains 3.0% by mass or more of SiO2 and Al2O3 in total and 1.0% by mass or more of carbon. A ratio of a metallic iron to the total iron content contained in the solid-state direct reduced iron is 90% by mass or more, and an excess carbon content Cx is 0.2% by mass or more to the carbons contained in the solid-state direct reduced iron. The method includes a step in a first furnace of melting 40 to 100% by mass of the 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 and a step in a second furnace of melting a remainder of the solid reduced iron together with the molten pig iron separated in the first furnace and blowing oxygen onto the molten material to decarburize into a molten steel.

Abstract: 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.

Abstract: 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.

Abstract: The first purpose of the present invention is to provide a method for producing metallic iron, whereby, in the production of metallic iron by heating an agglomerate, which comprises an iron oxide-containing material and a carbonaceous reductant, in a movable hearth type heating furnace, metallic iron can be efficiently collected from a reduced product containing metallic iron and a slag, said reduced product being obtained by heating the agglomerate.

Abstract: 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 Nm3/min to 0.004 Nm3/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 ?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: composition X: when composition of inclusions is converted to Al2O3+MgO+CaO+SiO2+MnO=100%, Al2O3+CaO+SiO2?70% is given. composition A: when composition of inclusions is converted to Al2O3+CaO+SiO2=100%, 20%?CaO?50% and Al2O3?30% are given; and composition B: when composition of inclusions is converted to Al2O3+CaO+SiO2=100%, CaO>50% is given.

Abstract: 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—CaO (T—CaO presumes total Ca converted to CaO): 35 to 55%, SiO2: 10 to 30%, Al2O3: 4.0% or less (excluding 0%), MgO: 0.2 to 1.0%, Li2O: 7 to 13%, F: 7 to 13%, C: 10.5 to 14%, and inevitable impurities; and satisfying: 1.6?[T—CaO]/[SiO2]?5 and 0.2?[Li2O]/[SiO2]?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.

Abstract: 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.

Abstract: 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.

Abstract: The invention provides a method of continuous casting for producing a slab excellent in surface quality by preventing formation of depressions and occurrence of cracking of a slab even in the case of producing a high Al steel having an Al content of 0.1% or more by continuous casting. At the time of continuous casting of a high-Al molten steel containing prescribed chemical components by using a mold powder, a powder containing T—CaO: 35 to 55%, SiO2: 10 to 30%, Al2O3: 4.0% or less (excluding 0%), MgO: 0.2 to 1.0%, Li2O: 7 to 13%, F: 7 to 13%, C: 10.5 to 14%, and inevitable impurities and satisfying 1.6?[T—CaO]/[SiO2]?5 and 0.2?[Li2O]/[SiO2]?1.1 is used as the mold powder, and operation is carried out while controlling the conditions such as 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 defined by a prescribed relational expression.

Abstract: 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.

Abstract: A method for manufacturing molten iron includes a step of 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 contained in the melting furnace from a bottom blowing tuyere disposed on a bottom of the melting furnace to stir the molten iron layer, wherein the carbonaceous material is charged so that a carbonaceous material suspending slag layer in which the carbonaceous material is suspended is formed in an upper portion of a slag layer formed on the molten iron layer by slag produced when the solid reduced iron is melted into the molten iron and so that a carbonaceous material coating layer composed of only the carbonaceous material is further formed on the carbonaceous material suspending slag layer, and the molten iron and the slag stored in the melting furnace are tapp

Abstract: The present invention provides a method suitable for manufacturing a steel material for obtaining a steel wire rod with decreased amount of hard nonmetallic inclusions and improved drawability and fatigue property by adequately controlling the conditions of secondary refining and manufacturing conditions in a converter. Converter blowing is performed by taking molten iron, cold iron, and steel scrap as main raw materials to be charged into a converter, the ratio of these components based on all the main raw materials being such that the molten iron takes 96 to 100% (means wt. %, same hereinbelow), the cold iron takes 4% or less, and the steel scrap takes 2% or less, and by setting an average P concentration in all the main raw materials to 0.02% or less, and operations are carried out such that a flow rate of gas for stirring molten steel during secondary refining after completion of the converter blowing is set to 0.0005 Nm3/min or more to 0.

Abstract: A bedding carbonaceous material is charged onto a hearth of a rotary hearth furnace, carbonaceous-material containing pellets containing powdery iron ore and powdery coal are placed on the bedding carbonaceous material, and the hearth is caused to pass inside the rotary hearth furnace to heat and reduce the carbonaceous-material containing pellets to solid reduced iron and to heat and dry the bedding carbonaceous material by distillation into char. Subsequently, the solid reduced iron and the char are charged into an iron-melting furnace without being substantially cooled, and an oxygen gas is blown into the iron-melting furnace to melt the solid reduced iron, thereby obtaining molten iron. At least a part of an exhaust gas from the iron-melting furnace is used as a fuel gas for the rotary hearth furnace after being cooled and having dust removed.

Abstract: 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 Nm3/min to 0.004 Nm3/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 Am 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: composition X: when composition of inclusions is converted to Al2O3+MgO+CaO+SiO2+MnO=100%, Al2O3+CaO+SiO2?70% is given. composition A: when composition of inclusions is converted to Al2O3+CaO+SiO2=100%, 20%?CaO?50% and Al2O3?30% are given; and composition B: when composition of inclusions is converted to Al2O3+CaO+SiO2=100%, CaO>50% is given.

Abstract: 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.

Abstract: 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.