Molten manganese-containing steel production method, holding furnace, and molten manganese-containing steel production equipment using holding furnace

Patent metadata

Field	Value
Publication number	US-2016053350-A1
Application number	US-201314783221-A
Country	US
Kind code	A1
Filing date	Apr 11, 2013
Priority date	Apr 11, 2013
Publication date	Feb 25, 2016
Grant date	—

Abstract

A manganese-containing molten steel production method comprises: a preparation step in which a molten ferroalloy or a molten non-ferrous metal is prepared by carrying out denitrification or nitrogen-absorption prevention during a procedure of retaining the molten ferroalloy or molten non-ferrous metal, in order to prevent later processing or additional denitrification due to nitrogen absorption; a maintaining step in which the molten ferroalloy or molten non-ferrous metal is maintained at a temperature at or above the melting point thereof; and a united pouring step in which the molten ferroalloy or molten non-ferrous metal is subjected to united pouring together with pre-prepared molten steel. In the present invention, while the maintaining step is being carried out, so too is a nitrogen-absorption prevention or denitrification step in which the molten ferroalloy or molten non-ferrous metal is subjected to nitrogen-absorption prevention or denitrification.

First claim

1 . A method of producing molten manganese-containing steel, the method comprising:
preparing a molten ferroalloy or a molten nonferrous metal; maintaining the molten ferroalloy or the molten nonferrous metal at a temperature equal to or higher than a melting point thereof; and pouring the molten ferroalloy or the molten nonferrous metal into prepared molten steel, wherein in the maintaining of the molten ferroalloy or the molten nonferrous metal, the molten ferroalloy or the molten nonferrous metal is subjected to a nitrogen-absorption prevention process or a denitrification process.

2 . The method of claim 1 , wherein the maintaining of the molten ferroalloy or the molten nonferrous metal is carried out in a holding furnace together with the nitrogen-absorption prevention process or the denitrification process, and
the nitrogen-absorption prevention process or the denitrification process comprises supplying argon (Ar) gas to the holding furnace as an atmospheric gas to maintain an interior of the holding furnace at a positive pressure.

3 . The method of claim 1 , wherein the maintaining of the molten ferroalloy or the molten nonferrous metal is carried out in a holding furnace together with the nitrogen-absorption prevention process or the denitrification process, and
the nitrogen-absorption prevention process or the denitrification process comprises agitating the molten ferroalloy or the molten nonferrous metal in at least one of upper and lower regions of the holding furnace using argon (Ar) gas.

4 . The method of claim 1 , wherein the nitrogen-absorption prevention process or the denitrification process comprises adding silicon (Si) to the molten ferroalloy such that the molten ferroalloy has a silicon (Si) content of 1.5 wt % or greater.

5 . The method of claim 2 , wherein the holding furnace comprises:
a case; an accommodation unit disposed in the case and comprising an internal space to accommodate a molten or solid ferroalloy or nonferrous metal; a heating unit configured to heat the ferroalloy or nonferrous metal contained in the accommodation unit; and a cover disposed on an upper side of the accommodation unit to close the internal space of the accommodation unit, wherein the cover comprises an atmospheric gas supply unit connected to an inert gas supply unit and supplying an atmospheric gas to the accommodation unit so that the ferroalloy or the nonferrous metal melted in the accommodation unit is denitrified or prevented from absorbing nitrogen.

6 . The method of claim 5 , wherein the preparing of the molten ferroalloy or the molten nonferrous metal is performed in the holding furnace.

7 . The method of claim 1 , wherein the molten ferroalloy or the molten nonferrous metal is prepared in an amount greater than a required amount in the pouring of the molten ferroalloy or the molten nonferrous metal, and
after the required amount of the molten ferroalloy or the molten nonferrous metal is poured into the molten steel, a remaining amount of the molten ferroalloy or the molten nonferrous metal is continuously maintained at a temperature equal to or greater than the melting point.

8 . The method of claim 2 , wherein the preparing of the molten ferroalloy or the molten nonferrous metal comprises melting solid FeMN or a solid Mn metal having a manganese (Mn) content and a phosphorus (P) content according to the following formula:
P content (wt %)<−0.026×(target Mn content (wt %) of Mn-containing molten steel+(4.72×10 −4 )×(target Mn content (wt %) of Mn-containing molten steel) 2 .

9 . The method of claim 6 , wherein the heating unit of the holding furnace comprises an induction coil, and
the preparing of the molten ferroalloy or the molten nonferrous metal comprises induction heating using the induction coil.

10 . The method of claim 1 , wherein the pouring of the molten ferroalloy or the molten nonferrous metal comprises:
pouring the molten ferroalloy or the molten nonferrous metal into a ladle in which the molten steel is contained; and agitating the molten steel together with the molten ferroalloy or the molten nonferrous metal, wherein the agitating is performed by supplying an inert gas through a lower side of the ladle.

11 . The method of claim 1 , wherein the pouring of the molten ferroalloy or the molten nonferrous metal comprises:
pouring the molten ferroalloy or the molten nonferrous metal into a ladle in which the molten steel is contained; and agitating the molten steel together with the molten ferroalloy or the molten nonferrous metal, wherein the agitating is performed using an agitator inserted through an upper side of the ladle into the molten steel and the molten ferroalloy or the molten nonferrous metal.

12 . The method of claim 1 , wherein in the maintaining of the molten ferroalloy or the molten nonferrous metal, the molten ferroalloy or the molten nonferrous metal is maintained at a temperature of 1300° C. to 1500° C., and
immediately prior to the pouring of the molten ferroalloy or the molten nonferrous metal, the method further comprises heating the molten ferroalloy or the molten nonferrous metal in consideration of states of the molten steel and target states of high manganese molten steel.

13 . The method of claim 1 , wherein after the pouring of the molten ferroalloy or the molten nonferrous metal, the method further comprises performing an RH vacuum refining process or a ladle furnace (LF) refining process in which at least one of Al, C, Cu, W, Ti, Nb, Sn, Sb, Cr, B, Ca, Si, and Ni is supplied to the molten steel and the molten ferroalloy or the molten nonferrous metal.

14 . The method of claim 13 , wherein the RH vacuum refining process is performed together with a dehydrogenation process.

15 . A holding furnace comprising:
a case; an accommodation unit disposed in the case and comprising an internal space to accommodate a solid or molten ferroalloy or a solid or molten nonferrous metal; a heating unit configured to heat the ferroalloy or nonferrous metal contained in the accommodation unit; and a cover disposed on an upper side of the accommodation unit to close the internal space of the accommodation unit, wherein the cover comprises an atmospheric gas supply unit connected to an inert gas supply unit and supplying an atmospheric gas to the accommodation unit so that the ferroalloy or the molten nonferrous metal melted in the accommodation unit is denitrified or prevented from absorbing nitrogen.

16 . The holding furnace of claim 15 , wherein the heating unit comprises at least one of:
an induction coil wound around the accommodation unit; an electrode bar disposed in the cover; and a plasma generator disposed in the cover.

17 . The holding furnace of claim 16 , further comprising a control unit connected to the heating unit,
wherein the molten ferroalloy or the molten nonferrous metal is maintained at a temperature of 1300° C. to 1500° C. under the control of the control unit, and immediately prior to the molten ferroalloy or the molten nonferrous metal is poured into molten steel, the molten ferroalloy or the molten nonferrous metal is heated under the control of the control unit.

18 . The holding furnace of claim 15 , wherein an atmospheric gas supply tube is disposed in the cover disposed on the upper side of the accommodation unit, and the cover comprises a vent to maintain an interior of the holding furnace at a constant positive pressure when an atmospheric gas is supplied to the interior of the holding furnace.

19 . The hold

Assignees

• Posco

Inventors

• Han Woong-Hee
• Yim Chang-Hee
• Song Min-Ho
• Kang Soo-Chang
• Ahn Chong-Tae

Classifications

• F27D7/02

  Supplying steam, vapour, gases or liquids · CPC title

• C21C5/5241

  in an inductively heated furnace · CPC title

• C21C7/0006

  Adding metallic additives · CPC title

• F27D7/06

  Forming or maintaining special atmospheres or vacuum within heating chambers (supplying steam, vapour, gases or liquids F27D7/02) · CPC title

• C21C5/5205

  in a plasma heated furnace · CPC title