Method for dephosphorization of molten iron

Patent metadata

Field	Value
Publication number	US-2024229177-A1
Application number	US-202218563597-A
Country	US
Kind code	A1
Filing date	Apr 19, 2022
Priority date	May 26, 2021
Publication date	Jul 11, 2024
Grant date	—

Abstract

A method for dephosphorization of molten iron includes, while blowing a hydrogen gas, a hydrocarbon gas, or a mixture of these gases into molten iron held in a vessel, supplying a slag-forming agent and an oxygen source to perform a dephosphorization treatment of the molten iron and obtain dephosphorized molten iron, and after the dephosphorization treatment, separating slag floating on a surface of the dephosphorized molten iron from the dephosphorized molten iron. In this method for dephosphorization of molten iron, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

First claim

1 . A method for dephosphorization of molten iron, comprising:
while blowing a hydrogen gas, a hydrocarbon gas, or a mixture of these gases into molten iron held in a vessel, supplying a flux and an oxygen source to perform a dephosphorization treatment of the molten iron and obtain dephosphorized molten iron, and after the dephosphorization treatment, separating slag floating on a surface of the dephosphorized molten iron from the dephosphorized molten iron.

2 . The method for dephosphorization of molten iron according to claim 1 , wherein
after the slag is separated, the dephosphorized molten iron is deoxidized with a deoxidizing agent.

3 . The method for dephosphorization of molten iron according to claim 1 , wherein
a carbon content in the molten iron before the dephosphorization treatment is 0.5 mass % or lower.

4 . The method for dephosphorization of molten iron according to claim 1 , wherein
the molten iron is obtained by melting a cold iron source.

5 . The method for dephosphorization of molten iron according to claim 4 , wherein
the cold iron source includes reduced iron.

6 . The method for dephosphorization of molten iron according to claim 1 , wherein
the vessel is a ladle.

7 . The method for dephosphorization of molten iron according to claim 1 , wherein
before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

8 . The method for dephosphorization of molten iron according to claim 2 , wherein a carbon content in the molten iron before the dephosphorization treatment is 0.5 mass % or lower.

9 . The method for dephosphorization of molten iron according to claim 2 , wherein the molten iron is obtained by melting a cold iron source.

10 . The method for dephosphorization of molten iron according to claim 3 , wherein the molten iron is obtained by melting a cold iron source.

11 . The method for dephosphorization of molten iron according to claim 8 , wherein the molten iron is obtained by melting a cold iron source.

12 . The method for dephosphorization of molten iron according to claim 9 , wherein the cold iron source includes reduced iron.

13 . The method for dephosphorization of molten iron according to claim 10 , wherein the cold iron source includes reduced iron.

14 . The method for dephosphorization of molten iron according to claim 11 , wherein the cold iron source includes reduced iron.

15 . The method for dephosphorization of molten iron according to claim 2 , wherein, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

16 . The method for dephosphorization of molten iron according to claim 3 , wherein, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

17 . The method for dephosphorization of molten iron according to claim 4 , wherein, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

18 . The method for dephosphorization of molten iron according to claim 5 , wherein, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

19 . The method for dephosphorization of molten iron according to claim 6 , wherein, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

Assignees

• Jfe Steel Corp

Inventors

• Ogasawara Futoshi
• Kawabata Ryo

Classifications

• C21C2300/08

  Particular sequence of the process steps · CPC title

• C21C7/072

  Treatment with gases (C21C7/06, C21C7/064, C21C7/068 take precedence) · CPC title

• C21C5/54

  Processes yielding slags of special composition · CPC title

• C21C1/02 Primary

  Dephosphorising or desulfurising · CPC title

• C21C7/10

  Handling in a vacuum · CPC title