A blast furnace operation method according to one aspect of the present invention includes: a process of acquiring a correlation between a carbon consumption in reducing gas and a reduction InputΔC in specific carbon consumption caused by blowing the reducing gas into the blast furnace per molar ratio C/H of carbon atoms to hydrogen atoms in the reducing gas; a process of determining a carbon consumption in the reducing gas where the reduction InputΔC in specific carbon consumption is a predetermined target value or higher on the basis of the correlation acquired per C/H; and a process of adjusting the amount of the reducing gas blown into the blast furnace on the basis of the determined carbon consumption in the reducing gas and the carbon proportion in the reducing gas.

A modular direct reduction system for producing direct reduced iron (DRI) includes a reformer system which receives a flow of feed gas and which discharges a flow of reducing gas, the reformer system including a plurality of separate reformer modules connected together and wherein each reformer module includes a reformer vessel including an internal chamber, a reactor tube extending through the internal chamber of the reformer vessel and containing a catalyst configured to react with the feed gas received by the reactor tube to form the reducing gas, and a burner to burn a fuel gas to heat the reactor tube, and a furnace system connected to the reformer system and including a furnace having a first inlet which receives an iron ore, a second inlet which receives the reducing gas from the reformer system to form the DRI, and an outlet which discharges the DRI.

A device to inject a reducing gas into a shaft furnace includes an external casing whose front face is provided with an outlet for gas injection into the shaft furnace, an internal casing located inside the external casing wherein reducing gas is circulating. The internal casing has an opening matching the gas injection outlet of the front face of the external casing. The front face of the external casing includes an upper and a lower part and the gas injection outlet is in the lower part and inwards from the upper part.

A blast furnace for ironmaking production wherein iron ore is at least partly reduced by a reducing gas which is injected in the stack of the blast furnace. The blast furnace includes an external and an internal wall, having a thickness T.sub.int, in contact with matters charged into the blast furnace. The thickness T.sub.int of the internal wall is substantially constant above and below the injection area of a reducing gas.

A blast furnace for ironmaking production wherein iron ore is at least partly reduced by a reducing gas which is injected in the stack of the blast furnace. The blast furnace includes an external and an internal wall, having a thickness T.sub.int, in contact with matters charged into the blast furnace. The thickness T.sub.int of the internal wall is substantially constant above and below the injection area of a reducing gas.

A method for operating a blast furnace for producing of pig iron, includes the following steps heating a first stream of steam in a first heater, before or after having been mixed with an oxygen source selected from oxygen and oxygen-enriched air, to provide a first heated stream of oxygen-enriched steam; heating a first stream of blast furnace gas from the blast furnace and a first stream of natural gas in a second heater, before or after being mixed together, to provide a heated carbon feed stream; feeding the first heated stream of oxygen-enriched steam and the heated carbon feed stream either as a combined stream or separately to a catalytic partial oxidation reactor to produce a stream of syngas; and feeding the stream of syngas to the shaft of the blast furnace.

A method for operating a blast furnace for producing of pig iron, includes the following steps heating a first stream of steam in a first heater, before or after having been mixed with an oxygen source selected from oxygen and oxygen-enriched air, to provide a first heated stream of oxygen-enriched steam; heating a first stream of blast furnace gas from the blast furnace and a first stream of natural gas in a second heater, before or after being mixed together, to provide a heated carbon feed stream; feeding the first heated stream of oxygen-enriched steam and the heated carbon feed stream either as a combined stream or separately to a catalytic partial oxidation reactor to produce a stream of syngas; and feeding the stream of syngas to the shaft of the blast furnace.

A method of operating an ironmaking or steelmaking plant with low CO.sub.2-emissions is provided. Hydrogen and oxygen are generated by water decomposition and at least part of the generated hydrogen is injected as a reducing gas into one or more ironmaking furnaces with off-gas decarbonation and reinjection into the furnaces of at least a significant part of the decarbonated off-gas and at least part of the generated oxygen is injected as an oxidizing gas in the one or more ironmaking.

A method of operating an ironmaking or steelmaking plant with low CO.sub.2-emissions is provided. Hydrogen and oxygen are generated by water decomposition and at least part of the generated hydrogen is injected as a reducing gas into one or more ironmaking furnaces with off-gas decarbonation and reinjection into the furnaces of at least a significant part of the decarbonated off-gas and at least part of the generated oxygen is injected as an oxidizing gas in the one or more ironmaking.

A fine ratio measuring device that measures the fine ratio of fines adhering to the surface of the material in the form of lumps includes: an illumination unit that illuminates the material in the form of lumps; an imaging unit that captures an image of the material in the form of lumps and produces image data; and an arithmetic unit including a computation unit that computes a characteristic quantity of the image data produced by the imaging unit and a conversion unit that converts the characteristic quantity computed by the computation unit to the fine ratio.