Method for predicting degree of contamination of molten steel during ladle exchange

Patent metadata

Field	Value
Publication number	US-9460248-B2
Application number	US-201313778933-A
Country	US
Kind code	B2
Filing date	Feb 27, 2013
Priority date	Aug 30, 2010
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

Predicting a degree of molten steel contamination during ladle exchange includes setting a casting quantity (Q) and a residual quantity (Qrm). Casting quantity (Q) is the molten steel amount transferred from a tundish to a mold when a first ladle operation ends. Residual quantity (Qrm) is the molten steel amount existing in the tundish when a second ladle starts. Casting amount (Qplug), a first contaminant concentration is calculated as a function of Q rm and a proportional coefficient. Casting amount (Qpeak), the amount a second contaminant concentration, is calculated as a function of Q rm and a second proportional coefficient. A preliminary degree of contamination is a linear function of Q, Qplug, and Qpeak. A second preliminary degree of contamination is an exponential function of Q, Qplug, and Qpeak. The smaller of the two preliminary degrees of contamination is selected to obtain a degree of contamination at the ladle operation end and a second degree of contamination at the second ladle operation start.

First claim

The invention claimed is:

1. A method for predicting a degree of contamination of molten steel during ladle exchange, the method comprising the steps of:
providing a first ladle conveying a quantity of molten steel;
providing a second ladle conveying a quantity of molten steel;
the first ladle and second ladle each performing an operation to supply the respective quantity of molten steel to a tundish in turn;
a contamination prediction system, (1) determining a casting quantity (Q), the amount of molten steel transferred from the tundish to a mold at the end of an operation of the first ladle, and determining a residual quantity (Qrm), an amount of molten steel existing in the tundish at the start of the operation of the second ladle; (2) calculating, a first casting amount (Qplug), the casting amount of the molten steel contained in the tundish, when a concentration of contaminants is substantially 0.1, Qplug being determined as a function of Qrm and a first proportional coefficient (g), where g is determined as Qplug/Qrm and has a value between 0.1 and 0.3, and calculating a second casting amount (Qpeak), which is the casting amount of the molten steel contained in the tundish, when a concentration of contaminants is substantially 1, Qpeak being determined as a function of Qrm and a second proportional coefficient (h), where h is determined as Qpeak/Qrm and has a value between 0.2 and 0.4; (3) determining a first preliminary degree of contamination as a linear function of the casting quantity Q, the first casting amount Qplug, and the second casting amount Qpeak, and determining a second preliminary degree of contamination as an exponential function of the casting quantity Q, the first casting amount Qplug, and the second casting amount Qpeak; and (4) obtaining a first degree of contamination at the end of the operation of the first ladle and obtaining a second degree of contamination at the start of the operation of the second ladle by selecting the a smaller of the first preliminary degree of contamination and the second preliminary degree of contamination.

2. The method of claim 1 , wherein when the first degree of contamination at the end of the operation of the first ladle is obtained, the first proportional coefficient (g) has a value of 0.1 to 0.2, and the second proportional coefficient (h) has a value of 0.2 to 0.3; when the second degree of contamination at the start of the operation of the second ladle is obtained, the first proportional coefficient (g) has a value of 0.1 to 0.3 and the second proportional coefficient (h) has a value of 0.2 to 0.4.

3. The method of claim 1 , wherein, in step (3), the linear function is represented by the following equation 1:

(

Q
-

Q
plug

)

(

Q
peak

-

Q
plug

)

Equation
⁢

⁢
1

and the exponential function is represented by the following equation 2:

exp
⁡

(

-
f

·

(

Q

Q
rm

-

Q
peak

)

)

Equation
⁢

⁢
2

wherein f is a third proportional coefficient having a value from 3 to 8.

4. The method of claim 1 , further comprising the step of determining a total degree (Tc) of contamination as a function of the first degree of contamination and the second degree of contamination.

5. The method of claim 4 , wherein the Tc is calculated by the following equation 3:
Tc=A×C 1(1− A )× C 2  Equation 3

wherein C 1 is the first degree of contamination, C 2 is the second degree of contamination, and A is a weight value.

6. The method of claim 5 , wherein the weight value (A) has a value from 0.25 to 0.35.

7. The method of claim 1 , further comprising, a step of selecting the greater of the selected smaller preliminary degree of contamination and zero to obtain the first preliminary degree of contamination or the second preliminary degree of contamination.

Assignees

• Hyundai Steel Co

Inventors

• Ahn Jae Hwan
• Kim Kyung Soo
• Moon Hong Kil

Classifications

• B22D11/16 Primary

  Controlling or regulating processes or operations · CPC title

• C21C1/04

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

• G06F30/23 Primary

  using finite element methods [FEM] or finite difference methods [FDM] · CPC title

• B22D11/181

  responsive to molten metal level or slag level · CPC title

• B22D1/00 Primary

  Treatment of fused masses in the ladle or the supply runners before casting {(for continuous casting B22D11/10; metallurgical processing, e.g. refining of iron or other metal C21, C22, C25C)} · CPC title