A method for converting a blast furnace plant for synthesis gas utilization includes:

constructing a syngas stove, and constructing a syngas supply system for connecting the syngas stove to a blast furnace;

connecting a first syngas stove to the top-gas supply system, the cold-blast and hot-blast supply systems and operating the first syngas stove for hot blast generation;

disconnecting a first original stove from the top-gas supply system, the cold-blast and hot-blast supply systems; and

converting the first original stove to adapt it for producing syngas. The method includes

connecting the first original stove to the top-gas supply system;

disconnecting the first syngas stove from the cold-blast and hot-blast supply systems, connecting the first original stove and first syngas stove to a gas-combination supply system; and

operating the first original stove and first syngas stove to produce and then supply syngas to the blast furnace via the syngas supply system.

A method for operating a metallurgical furnace and a simplified way of providing synthesis gas for a metallurgical furnace, includes the following steps performing a combustion process outside the metallurgical furnace by combusting a carbon-containing material with an oxygen-rich gas to produce an offgas, which offgas is a CO.sub.2 containing gas; and combining the offgas, while having an elevated combustion-induced temperature due to the combustion process, with a hydrocarbon-containing fuel gas to obtain a first gas mixture having a temperature above a reforming temperature necessary for a reforming process, preferably a dry reforming process; the first gas mixture undergoing the reforming process, thereby producing a synthesis gas containing CO and H.sub.2, the reforming process being performed non-catalytically; and feeding the synthesis gas into the metallurgical furnace.

A method for operating a metallurgical furnace and a simplified way of providing synthesis gas for a metallurgical furnace, includes the following steps performing a combustion process outside the metallurgical furnace by combusting a carbon-containing material with an oxygen-rich gas to produce an offgas, which offgas is a CO.sub.2 containing gas; and combining the offgas, while having an elevated combustion-induced temperature due to the combustion process, with a hydrocarbon-containing fuel gas to obtain a first gas mixture having a temperature above a reforming temperature necessary for a reforming process, preferably a dry reforming process; the first gas mixture undergoing the reforming process, thereby producing a synthesis gas containing CO and H.sub.2, the reforming process being performed non-catalytically; and feeding the synthesis gas into the metallurgical furnace.

A plant complex may include a unit that produces CO.sub.2-containing gases, a gas conducting system for CO.sub.2-containing gases, a gas/liquid separation system, a reformer that is connected to the gas conducting system and where the CO.sub.2-containing gas reacts with H.sub.2 and/or hydrocarbons to give a CO— and H.sub.2-containing synthesis gas mixture. The reformer is connected to a reactor for producing higher alcohols in which the synthesis gas mixture reacts with H.sub.2 to give a gas/liquid mixture containing higher alcohols. For separating off the alcohols of the gas/liquid mixture, the gas/liquid separation system is connected to the reactor for producing higher alcohols.

According to a certain viewpoint of the present invention, there is provided a blast furnace operation method comprising blowing a high-concentration hydrogen-containing gas containing 80 mol % or more of hydrogen gas from a tuyere under: a condition in which a blowing temperature of the high-concentration hydrogen-containing gas is room temperature or higher and 300° C. or lower and a gas volume of the hydrogen gas in the high-concentration hydrogen-containing gas is 200 Nm.sup.3/t or more and 500 Nm.sup.3/t or less; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 300° C. and 600° C. or lower and the gas volume of the hydrogen gas in the high-concentration hydrogen-containing gas is 145 Nm.sup.3/t or more; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 600° C. and 900° C. or lower and the gas volume of the high-concentration hydrogen-containing gas is 125 Nm.sup.3/t or more, or the like.

According to a certain viewpoint of the present invention, there is provided a blast furnace operation method comprising blowing a high-concentration hydrogen-containing gas containing 80 mol % or more of hydrogen gas from a tuyere under: a condition in which a blowing temperature of the high-concentration hydrogen-containing gas is room temperature or higher and 300° C. or lower and a gas volume of the hydrogen gas in the high-concentration hydrogen-containing gas is 200 Nm.sup.3/t or more and 500 Nm.sup.3/t or less; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 300° C. and 600° C. or lower and the gas volume of the hydrogen gas in the high-concentration hydrogen-containing gas is 145 Nm.sup.3/t or more; a condition in which the blowing temperature of the high-concentration hydrogen-containing gas is higher than 600° C. and 900° C. or lower and the gas volume of the high-concentration hydrogen-containing gas is 125 Nm.sup.3/t or more, or the like.

A method for producing direct reduced iron is provided. The method includes circulating a first stream of spent reducing gas exiting a reactor in a reducing gas circuit through at least one carbon dioxide removal unit and a reducing gas heater and the reactor. The method also includes mixing the first stream with reducing gas containing heavier hydrocarbons than methane.

The use of pellets comprising one or more thermoplastic material(s) of more than 40%, based on the total dry weight of the pellets and one or more cellulosic material(s) of more than 20%, based on the total dry weight of the pellets, as a reducing agent in a process for making pig iron in a blast furnace. The pellets can be provided in unground form, as a partial replacement of coke through the top of the blast furnace, or can be provided as reducing agent in the raceway in an amount of higher than 10 kg/ton iron.

The use of pellets comprising one or more thermoplastic material(s) of more than 40%, based on the total dry weight of the pellets and one or more cellulosic material(s) of more than 20%, based on the total dry weight of the pellets, as a reducing agent in a process for making pig iron in a blast furnace. The pellets can be provided in unground form, as a partial replacement of coke through the top of the blast furnace, or can be provided as reducing agent in the raceway in an amount of higher than 10 kg/ton iron.

Provided is a method of operating a blast furnace, including generating a regenerative methane gas using a blast furnace by-product gas, and blowing a blast gas and a reducing agent into the blast furnace from a tuyere, in which the blast gas is oxygen gas, the regenerative methane gas is used as at least part of the reducing agent, and the oxygen gas and/or the regenerative methane gas is preheated before being blown into the blast furnace from the tuyere.