Method for operating converter and method for producing molten steel

Patent metadata

Field	Value
Publication number	US-2024167112-A1
Application number	US-202118282266-A
Country	US
Kind code	A1
Filing date	Nov 4, 2021
Priority date	Mar 17, 2021
Publication date	May 23, 2024
Grant date	—

Abstract

When supplying oxygen source to molten pig iron inside a converter-type refining furnace and performing desiliconization, dephosphorization, and decarburization refining, one or more of slag removal flow shape, slag removal flow velocity, and slag surface shape while discharging slag through a throat is measured to estimate one or both of a slag removal amount and physical properties of removed slag. When sequentially performing one or both of desiliconization and dephosphorization, an intermediate step of discharging part or all of generated slag through the throat, and the remaining other refining step, in the intermediate step, the method measures one or two of slag removal flow shape, slag removal flow velocity, and slag surface shape, estimates one or both of amount and physical properties of slag removed, estimates remaining slag amount, or remaining slag amount and composition, and determines an auxiliary raw material amount to be fed in the other refining step.

First claim

1 - 6 . (canceled)

7 . A method for operating a converter that supplies an oxygen source to molten pig iron inside a converter-type refining furnace and performs desiliconization refining of the molten pig iron, and dephosphorization refining and decarburization refining of the molten pig iron,
wherein the method measures one or two or more selected from a slag removal flow shape, a slag removal flow velocity, and a slag surface shape when removing slag through a throat to estimate one or both of an amount and physical properties of removed slag.

8 . A method for operating a converter that, when supplying a gaseous oxygen source to molten pig iron inside a converter-type refining furnace through a top-blowing lance and optionally further blowing in an oxidizing gas or an inert gas through a bottom-blowing tuyere to perform desiliconization refining of the molten pig iron and dephosphorization refining and decarburization refining of the molten pig iron, selects one of the following combinations of refining steps:
a combination of one refining step of performing part of desiliconization refining of the molten pig iron, and another refining step of performing dephosphorization refining of the molten pig iron after the desiliconization refining alone or in combination with decarburization refining; and another combination of one refining step of performing one or both of desiliconization refining and dephosphorization refining of the molten pig iron, and another refining step of performing one or both of dephosphorization refining and decarburization refining of the molten pig iron, and performs, between the one refining step and the other refining step, an intermediate slag removal step of removing slag generated in the one refining step through a throat, characterized by, in the intermediate slag removal step, measuring one or two or more selected from a slag removal flow shape, a slag removal flow velocity, and a slag surface shape to estimate one or both of an amount and physical properties of removed slag; estimating an amount of slag remaining inside the converter-type refining furnace, or the amount and composition of slag remaining inside the converter-type refining furnace; and determining, based on the estimation result, an amount of auxiliary raw material to be fed in one of the types of refining in the other refining step.

9 . The method for operating a converter according to claim 7 , wherein
the method estimates a mass-based slag removal amount W (t) from a horizontal distance L (m) reached by a slag removal flow at a certain distance down from the throat and a slag thickness h e (m) at a throat position using the relational expressions of the following Mathematical Expressions 1 to 3:

[

Expression
⁢

1

]



W
=

∫
0
t

Δ
⁢
W
/
Δ
⁢

t
·
dt

(
1
)

[

Expression
⁢

2

]



Δ
⁢
W
/
Δ
⁢
t

=

∫
0
h

ρ
⁢

w
⁡
(
h
)

⁢

v
⁡
(
h
)

·
dh

+
b

=

aw
e

⁢

v
e

⁢

h
e

+
b

(
2
)

[

Expression
⁢

3

]



v
e

=

L
=

g

2
⁢
H

(
3
)

where

Assignees

• Jfe Steel Corp

Inventors

• Amano Shota
• Kono Yuki

Classifications

• C21C1/02 Primary

  Dephosphorising or desulfurising · CPC title

• C21C1/04

  Removing impurities other than carbon, phosphorus or sulfur · CPC title

• C21C5/32

  Blowing from above (C21C5/35 takes precedence) · CPC title

• C21C5/36

  Processes yielding slags of special composition · CPC title

• C21C5/4673 Primary

  Measuring and sampling devices · CPC title