Method of operating blast furnace and blast furnace ancillary facility

A method of operating a blast furnace, comprising

• generating a regenerative methane gas using a blast furnace by-product gas which is a by-product gas discharged from the blast furnace, and
• blowing a blast gas and a reducing agent into the blast furnace from a tuyere,
• wherein 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,
• a consumption rate of circulating carbon atoms in the reducing agent is 55 kg/t or more, and
• the consumption rate of circulating carbon atoms is a carbon equivalent mass of the regenerative methane gas that is blown into the blast furnace as the reducing agent for producing 1 t of hot metal, and is obtained by the following equation:
• [Consumption rate of circulating carbon atoms (kg/t)]=[Mass of methane in regenerative methane gas blown into blast furnace as reducing agent (kg)]×(12/16):
• [Production amount of hot metal (t)].