Method for producing reduced iron
AssigneeNippon Steel Corporation
InventorsTakanobu Inada, Moritoshi Mizutani, Yutaka Ujisawa, Naoto Yasuda, Hitoshi Funagane
Life of this patent
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Abstract
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.
Claims2
A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace,
- wherein all of a reducing gas supplied from outside is blown into a cooling zone of the reduced iron provided at a lower portion of the shaft furnace at normal temperature,
- a heated gas mixture which contains a reducing gas which is an unreacted gas and a nitrogen gas, separated from a furnace top, is blown into the shaft furnace from a tuyere equipped at a lower portion of a reduction zone of the shaft furnace,
- the reducing gas supplied from the outside contains 90 volume % or more of a hydrogen gas,
- a lower limit value of a blowing amount of the reducing gas blown into the cooling zone is 600 Nm3/t-Fe,
- the reducing gas that has flowed up in the cooling zone is used for reduction of the iron oxide,
- at least the hydrogen gas which is the unreacted gas and the nitrogen gas are separated and collected from a top gas of the shaft furnace,
- the separated and collected hydrogen gas and nitrogen gas are used as the gas mixture, and
- a blowing amount of the nitrogen gas blown into the shaft furnace from the tuyere equipped at the lower portion of the reduction zone is 330 Nm3/t-Fe or more and 800 Nm3/t-Fe or less.
A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace,
- wherein a heated gas mixture which contains a reducing gas which is an unreacted gas and a nitrogen gas, separated from a furnace top, is blown into the shaft furnace from a tuyere equipped at a lower portion of a reduction zone of the shaft furnace,
- an ammonia gas is blown into a cooling zone of the reduced iron provided at a lower portion of the shaft furnace at normal temperature,
- a hydrogen gas and a nitrogen gas generated by decomposition of the ammonia gas while flowing up in the cooling zone are used as part of the gas mixture,
- at least the hydrogen gas which is the unreacted gas and the nitrogen gas is separated and collected from a top gas of the shaft furnace,
- a part of the separated and collected hydrogen gas and nitrogen gas are used as the gas mixture, and a rest is used as a fuel gas at a time of heating the gas mixture, and
- the amount of the nitrogen gas that circulates in the shaft furnace is held constant.
Dependencies are inferred from the claim text.