In an embodiment, gas emitted during DRI processing and melting is collected and blown in refining, and gas emitted from the refining is collected and used in DRI processing, so that it is possible to circulate gas input to and emitted from each process in a DRI-Smelter-BOF (Basic Oxygen Furnace) scheme and achieve process optimization.

An embodiment provides a method and a system device for refining molten iron, wherein hydrogen reduction DRI is utilized to collect CO.sub.2 gas generated during melting and further reduction and use the gas in decarbonization refining, so as to optimize processes and achieve carbon neutrality. In addition, it is possible to predict the end point of the decarbonization refining by measuring the amount of CO gas generated in decarbonization refining.

A method for producing direct reduction iron includes reducing an iron oxide raw material by a reducing gas containing hydrogen gas to generate direct reduction iron; removing water from an exhaust gas in the reducing and thus hydrogen gas is separated from the exhaust gas; carbonizing and cooling the direct reduction iron using a cooling gas containing carbon as an element, and separating hydrogen gas and methane gas from an exhaust gas in the carbonizing and cooling, wherein the cooling gas is methane gas, wherein the reducing gas further contains the hydrogen gas separated in the removing and the hydrogen gas separated in the separating, and wherein the cooling gas further contains the methane gas separated in the separating.

The invention relates to a method for operating a steelworks, for example in a blast furnace converter route, or with a direct reduction of iron ore with hydrogen with downstream electrical steel route, preferably additionally a secondary steel route. To carry out the method, the following are balanced: A) a number of starting material flows of supplied starting materials, B) a number of by-product material flows from emitted by-products, and C) a number of energy flows of used energy.

A method and system for producing synthesis gas for the production of direct reduced iron in a direct reduction shaft furnace, including: preheating cold feed gas in a heater to form hot feed gas; adding preheated external hydrogen gas to the hot feed gas downstream of the heater; feeding the hot feed gas and the preheated external hydrogen added to the hot feed gas to a reformer; and reforming the hot feed gas and the preheated external hydrogen added to the hot feed gas in the reformer to form the synthesis gas. The method and system also include feeding the synthesis gas to a bustle of the direct reduction shaft furnace for the production of the direct reduced iron in the direct reduction shaft furnace. The method may include adding preheated external hydrogen gas to the synthesis gas downstream of the reformer and upstream of the direct reduction shaft furnace.

Proposed is a system for carbon dioxide capture and carbon recycling for a steel mill. The system includes a fluidized bed reduction furnace configured to reduce fine iron ore to reduced iron by using a reducing gas, a first discharge means configured to discharge an exhaust gas generated from the fluidized bed reduction furnace, a melting furnace configured to manufacture molten iron, a second discharge means configured to discharge an exhaust gas generated from the melting furnace, and a reactor configured such that when the reactor receives the exhaust gas discharged from the fluidized bed reduction furnace and the melting furnace as the reducing gas, the reactor captures carbon dioxide in the reducing gas by reacting the reducing gas with a basic alkaline mixture solution, and then collects a reactant and injects, into the fluidized bed reduction furnace, the reducing gas from which carbon dioxide is removed.

A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace, in which a gas mixture which contains a reducing gas and a nitrogen gas, and has a predetermined temperature, is blown into the shaft furnace. The reducing gas contains 90 volume % or more of a hydrogen gas.

System and method for producing steel is provided that efficiently reduce carbon dioxide emissions. A steel production system includes: a first gas generating section configured to obtain a first gas by converting carbon monoxide, to carbon dioxide, in a gas containing the carbon dioxide and carbon monoxide; a reducing gas supply section 3 configured to supply a reducing gas containing a reducing substance to reduce a reducing agent, the reducing agent containing metal oxide to reduce carbon dioxide and being oxidized by contact with the carbon dioxide; and a reaction section 4 including a plurality of reactors 4a and 4b, respectively connected to at least one of the first gas generating section and the reducing gas supply section 3, and the reducing agent arranged in the reactors 4a and 4b, the reaction section being capable of switching between the first gas and the reducing gas to be supplied to each of the reactors 4a and 4b, wherein a second gas is configured to be supplied to a blast furnace, the second gas being obtained by contacting the first gas supplied to the reactors 4a and 4b with the reducing agent to convert the carbon dioxide to carbon monoxide and the second gas having the carbon monoxide as a main component.

A method for producing molten iron. The reduction of iron oxide-containing material to form a metallized product is performed using a reduction gas consisting at least largely of hydrogen H2. Top gas is accumulated during the reduction process. First sub-quantity of top gas is combined with reducing reduction gas components to provide reduction gas, and second sub-quantity of the top gas, as a discharged gas, is subjected to a gas separation process into a hydrogen-enriched gas flow and a hydrogen-depleted tail gas flow. Metallized product of the reduction process is combined with carbon carriers to be melted in a melting device to form a molten iron, and a smelting exhaust gas is accumulated. Sub-quantity of the tail gas flow is combined with at least a sub-quantity of the smelting exhaust gas, and a tail gas mixture is produced. Sub-quantity of the tail gas mixture is supplied to a thermal use.

A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace, in which a heated gas mixture which contains a reducing gas and a nitrogen gas, the reducing gas containing 90 volume % or more of a hydrogen gas, is blown into the shaft furnace from a tuyere equipped at a lower portion of a reduction zone of the shaft furnace, at least part of the reducing gas is blown into a cooling zone of the reduced iron provided at a lower portion of the shaft furnace at normal temperature, and the reducing gas that has flowed up in the cooling zone is used for reduction of the iron oxide.