Method for producing reduced iron

Patent metadata

Field	Value
Publication number	US-12486548-B2
Application number	US-202117921654-A
Country	US
Kind code	B2
Filing date	May 13, 2021
Priority date	May 14, 2020
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace, in which a gas mixture which contains a reducing gas and a nitrogen gas, and has a predetermined temperature, is blown into the shaft furnace. The reducing gas contains 90 volume % or more of a hydrogen gas.

First claim

The invention claimed is:

1 . A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace, the method comprising:
wherein a heated gas mixture which contains a reducing gas and a nitrogen gas is blown into the shaft furnace, the reducing gas containing 90 volume % or more of a hydrogen gas, and wherein, without changing a blow temperature and a blow amount of the hydrogen gas per unit time, the amount of the reduced iron produced per unit time is increased by increasing the amount of the nitrogen gas added.

2 . A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace, the method comprising:
heating a gas mixture which contains a reducing gas and a nitrogen gas, the reducing gas containing 90 volume % or more of a hydrogen gas, and blowing the heated gas mixture into the shaft furnace, and wherein, without changing a blow temperature and a blow amount of the hydrogen gas per unit time, the amount of the reduced iron produced per unit time is increased by increasing the amount of the nitrogen gas added.

3 . The method for producing reduced iron according to claim 2 , the method comprising:
separating and collecting at least unreacted hydrogen gas and nitrogen gas from a furnace top gas of the shaft furnace; and reusing the separated and collected hydrogen gas and nitrogen gas as part of the gas mixture.

4 . The method for producing reduced iron according to claim 3 , the method comprising:
using part of the separated and collected hydrogen gas and nitrogen gas as a fuel gas at a time of heating the gas mixture.

5 . A method for producing reduced iron that produces reduced iron by reducing iron oxide charged in a shaft furnace, the method comprising:
separately heating a reducing gas and a nitrogen gas, the reducing gas containing 90 volume % or more of a hydrogen gas, mixing the heated reducing gas and the heated nitrogen gas to prepare a gas mixture, and blowing the gas mixture into the shaft furnace.

6 . The method for producing reduced iron according to claim 5 ,
wherein a heating temperature of the nitrogen gas is higher than a heating temperature of the reducing gas.

7 . The method for producing reduced iron according to claim 5 , the method comprising:
separating and collecting at least unreacted hydrogen gas and nitrogen gas from a furnace top gas of the shaft furnace; and reusing the separated and collected hydrogen gas and nitrogen gas as the reducing gas and the nitrogen gas to be heated.

8 . The method for producing reduced iron according to claim 1 ,
wherein, in the gas mixture, a proportion of the nitrogen gas is 90 volume % or less of the reducing gas.

9 . The method for producing reduced iron according to claim 1 ,
wherein, at a time of blowing the gas mixture into the shaft furnace, a temperature of the gas mixture is 900° C. or lower.

10 . The method for producing reduced iron according to claim 2 ,
wherein, in the gas mixture, a proportion of the nitrogen gas is 90 volume % or less of the reducing gas.

11 . The method for producing reduced iron according to claim 2 ,
wherein, at a time of blowing the gas mixture into the shaft furnace, a temperature of the gas mixture is 900° C. or lower.

12 . The method for producing reduced iron according to claim 5 ,
wherein, in the gas mixture, a proportion of the nitrogen gas is 90 volume % or less of the reducing gas.

13 . The method for producing reduced iron according to claim 5 ,
wherein, at a time of blowing the gas mixture into the shaft furnace, a temperature of the gas mixture is 900° C. or lower.

14 . The method for producing reduced iron according to claim 5 ,
wherein, without changing a blow temperature and a blow amount of the hydrogen gas per unit time, the amount of the reduced iron produced per unit time is increased by increasing the amount of the nitrogen gas added.

Assignees

• Nippon Steel Corp

Inventors

• Inada Takanobu
• Mizutani Moritoshi
• Ujisawa Yutaka

Classifications

• C21B13/02 Primary

  in shaft furnaces · CPC title

• C21B2100/40

  Gas purification of exhaust gases to be recirculated or used in other metallurgical processes · CPC title

• C21B2100/64

  Controlling the physical properties of the gas, e.g. pressure or temperature · CPC title

• C21B2100/28

  by separation · CPC title

• F27D17/00

  Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases · CPC title