Abstract: A molten material liquid level detection method that can detect a liquid level of molten material from a residual amount of the molten material with high accuracy and a method for operating a vertical furnace by using the detection method. The molten material liquid level detection method detects a liquid level of molten material remaining in a bottom portion of a vertical furnace after end of discharge of a molten material. The molten material liquid level detection method includes calculating a void fraction of the solid-filled structure, and detecting a liquid level of the molten material after the end of the discharge by using the calculated void fraction and a residual amount of the molten material after the end of the discharge.

Abstract: Provided is a steelmaking line contributing to the realization of a method that achieves energy saving and CO2 emission reduction when producing reduced iron from iron oxide. The steelmaking line comprises: a blast furnace configured to reduce iron oxide; a reducing furnace configured to reduce iron oxide; a methane synthesizer configured to synthesize methane from blast furnace gas and/or furnace top gas, and hydrogen gas; a blower configured to blow the methane gas synthesized by the methane synthesizer into the blast furnace; a heat-reformer configured to heat or heat-reform the blast furnace gas and/or the furnace top gas, and the methane gas synthesized by the methane synthesizer, to generate reducing gas; a reducing gas blower configured to blow the reducing gas into the reducing furnace; and a supply path configured to supply the furnace top gas to the methane synthesizer and/or the heat-reformer.

Abstract: 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.

Abstract: Provided is a method of operating a blast furnace, having generating a regenerative methane gas from 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 of the blast furnace in which the blast gas is oxygen gas and the regenerative methane gas is used as at least part of the reducing agent.

Abstract: A coke layer and an ore layer are formed in a blast furnace. The coke layer is formed of conventional coke and the ore layer is formed of carbon iron composite, conventional coke, and ore. The mixing percentage of the conventional coke in the ore layer with respect to the ore is 0.5 mass % or more. Slowing of the gasification reaction of carbon iron composite in the cohesive zone can be suppressed.

Abstract: A coke layer and an ore layer are formed in a blast furnace. The coke layer is formed of conventional coke and the ore layer is formed of carbon iron composite, conventional coke, and ore. The mixing percentage of the conventional coke in the ore layer with respect to the ore is 0.5 mass % or more. Slowing of the gasification reaction of carbon iron composite in the cohesive zone can be suppressed.