WO1992015413A1 - A method and arrangement for purging molten metal in a container with the aid of a gas - Google Patents

A method and arrangement for purging molten metal in a container with the aid of a gas Download PDF

Info

Publication number
WO1992015413A1
WO1992015413A1 PCT/SE1992/000103 SE9200103W WO9215413A1 WO 1992015413 A1 WO1992015413 A1 WO 1992015413A1 SE 9200103 W SE9200103 W SE 9200103W WO 9215413 A1 WO9215413 A1 WO 9215413A1
Authority
WO
WIPO (PCT)
Prior art keywords
nozzle
gas
molten metal
container
arrangement
Prior art date
Application number
PCT/SE1992/000103
Other languages
French (fr)
Inventor
Thomas Falk
Original Assignee
Mefos Stiftelsen För Metallurgisk Forskning
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mefos Stiftelsen För Metallurgisk Forskning filed Critical Mefos Stiftelsen För Metallurgisk Forskning
Publication of WO1992015413A1 publication Critical patent/WO1992015413A1/en

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00Treatment of fused masses in the ladle or the supply runners before casting
    • B22D1/002Treatment with gases
    • B22D1/005Injection assemblies therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00Treatment of fused masses in the ladle or the supply runners before casting
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27DDETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D3/00Charging; Discharging; Manipulation of charge
    • F27D3/16Introducing a fluid jet or current into the charge

Definitions

  • the present invention is concerned with the delivery of ⁇ 5 a pressurized gas to a molten metal bath contained in a container, for the purpose of purging and/or agitating the molten metal, in accordance with the preamble of Claim 1, and relates to a method of clearing the throughflow passage of a gas-delivery nozzle from the 10 solid metal blockages that are liable to occur when the delivery of gas to the melt is stopped.
  • the invention also relates to an arrangement according to the preamble of Claim 2 for carrying out the inventive method.
  • Ladles are used to transport and to treat molten metals in the steel, metal and ferroalloying industries.
  • an inert gas such as argon, is injected into the melt through the bottom of the ladle. Hitherto, this gas has
  • the molten material is unable to penetrate the pores or channels.
  • porous plugs place a limit on the gas- pressures that can be used, which in turn places a limit
  • the object of the present invention is to eliminate the aforesaid problems encountered with the use of nozzles for injecting gases into ladles, so as to enable the porous plugs used hitherto to be replaced with nozzles.
  • the inventive nozzle may, for example, be mounted on the bottom of a molten metal container, such as a ladle, converter or the like.
  • the nozzle is connected to a container which contains gas under high pressure, through the intermediary of a valve which functions to « control the gas flow and gas pressure.
  • the nozzle or a part of the nozzle, is comprised of an electrically conductive material of such electrical resistance as to generate heat when an electric current is passed therethrough.
  • the nozzle includes a heating wire which is connected to a source of electric current and which is wound around the nozzle tube or around the region of the gas throughflow passage, said
  • tube preferably being made of a ceramic material.
  • Pro ⁇ vided on the bottom end of the nozzle is a screw-thread ⁇ ed tube for connection with a quick-coupling between the nozzle and the conduit or pipe leading to the gas-flow control valve.
  • the nozzle is surrounded by a body of
  • the valve of the gas container is opened to allow gas to pass from the container while, at the same time causing an electric current to be applied to the nozzle, such as to heat at the nozzle and therewith
  • 2 orifice is suitably from 0.2 to 15mm , preferably from
  • the gas pressure will suitably lie in a range of from 5 to 250 bars, preferably from 10 to 50 bars. It will be understand from the aforegoing that when using nozzles to deliver a purging gas to molten metal contained in a ladle, the nozzle will become blocked by the molten metal which is drawn into the nozzle immedi- ately the supply of gas is cut-off, by closing the gas- flow control valve, this molten metal freezing on the nozzle walls and forming a solid plug. In accordance with the invention, when the valve is opened to allow pressurized gas to flow from the gas container an elec- trie current is, at the same time, supplied to the nozzle, which subsequently becomes hot enough to melt or at least partially melt the plug.
  • the force of the gas entering the nozzle is then suffi ⁇ cient to push the plug from the nozzle and into the molten metal bath.
  • the gas pressure and gas flow can then be adjusted to values appropriate to gas-purging purposes and also to the geometry of the container, i.e. the ladle or converter.
  • the arrangement also includes a monitoring means which monitors the state of gas throughflow and which func ⁇ tions to switch off the supply of electric current to the nozzle when gas flows freely therethrough

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Charging Or Discharging (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

In the purging and agitation of molten metal carried in a ladle by injecting a pressurized gas into the molten metal through the intermediary of a nozzle mounted on the wall or on the bottom of the container, there is proposed a method for clearing the nozzle of blockages that are caused by molten metal being drawn into the nozzle-throughtflow passage immediately the flow of pressurized gas is cut-off, and freezing on the walls of the nozzle to form a blockage. The inventive method is characterized by passing an electric current through at least part of the nozzle at the same as the supply of pressurized gas is switched on, such as to heat and therewith at least partially melt the metal blockage in the throughflow passage of the nozzle, this at least partially melted metal blockage being forced from the passage by the pressurized gas flowing therethrough.

Description

A Method and Arrangement for Purging Molten Metal in a Container with the aid of a Gas.
The present invention is concerned with the delivery of ^ 5 a pressurized gas to a molten metal bath contained in a container, for the purpose of purging and/or agitating the molten metal, in accordance with the preamble of Claim 1, and relates to a method of clearing the throughflow passage of a gas-delivery nozzle from the 10 solid metal blockages that are liable to occur when the delivery of gas to the melt is stopped. The invention also relates to an arrangement according to the preamble of Claim 2 for carrying out the inventive method.
15 Ladles are used to transport and to treat molten metals in the steel, metal and ferroalloying industries. In order to the agitate and refine, or purge, the melt an inert gas, such as argon, is injected into the melt through the bottom of the ladle. Hitherto, this gas has
20 been supplied through the intermediary of so-called purging stones or porous plugs, such plugs either con¬ sisting of a ceramic porous body or a ceramic body which contains many very fine channels. The pores or channels are so disposed in the plugs that while gas is able to
25 pass through, the molten material is unable to penetrate the pores or channels.
Such porous plugs are encumbered with several drawbacks. For example, it can be difficult to cause the plugs to
30 allow gas to pass therethrough while preventing molten metal or slag from entering the pores or channels and freezing on the walls thereof, so as to cause blockages. $ Furthermore, porous plugs place a limit on the gas- pressures that can be used, which in turn places a limit
35 on the volume of gas that can be injected into the melt. Because of the success obtained with the use of nozzles or like devices in converters, it has been desirable to use nozzles for the purpose of injecting purging gas into molten metal contained in ladles, instead of the aforesaid porous plugs. When attempting to replace porous plugs with nozzles, it was found that immediately the supply of purging gas was interrupted or terminated, molten metal was drawn into the nozzle and froze onto the walls of the gas-throughflow passage, therewith causing a blockage. Attempts to remove this frozen metal plug have generally failed, meaning that the gas was unable to flow through the nozzle. As a result of this problem, the use of nozzles in ladles for the aforesaid purpose has not been pursued. It should be mentioned that this problem does not occur in converters, because a converter can be tipped sideways when purging is not in progress, so that the nozzle opening or nozzle ori¬ fice is located above the surface of the metal bath.
The object of the present invention is to eliminate the aforesaid problems encountered with the use of nozzles for injecting gases into ladles, so as to enable the porous plugs used hitherto to be replaced with nozzles.
This object is achieved with the inventive method and the inventive arrangement, which have the characteristic features set forth in the characterizing clauses of respective method and apparatus claims.
The invention will now be described in more detail with reference to two exemplifying embodiments of an inven¬ tive nozzle arrangement.
The inventive nozzle may, for example, be mounted on the bottom of a molten metal container, such as a ladle, converter or the like. The nozzle is connected to a container which contains gas under high pressure, through the intermediary of a valve which functions to « control the gas flow and gas pressure.
* 5 According to a first embodiment of the invention the nozzle, or a part of the nozzle, is comprised of an electrically conductive material of such electrical resistance as to generate heat when an electric current is passed therethrough.
10
According to a second embodiment the nozzle includes a heating wire which is connected to a source of electric current and which is wound around the nozzle tube or around the region of the gas throughflow passage, said
15 tube preferably being made of a ceramic material. Pro¬ vided on the bottom end of the nozzle is a screw-thread¬ ed tube for connection with a quick-coupling between the nozzle and the conduit or pipe leading to the gas-flow control valve. The nozzle is surrounded by a body of
20 ceramic material. When injecting gas into the bath of molten metal, the valve of the gas container is opened to allow gas to pass from the container while, at the same time causing an electric current to be applied to the nozzle, such as to heat at the nozzle and therewith
25 melt, or partially melt, the frozen metal plug in the nozzle tube or nozzle throughflow-passage. This molten, or semi-molten metal, will then be blown from the nozzle tube and into the metal bath by the pressurized gas entering the nozzle tube, and therewith
30 enable the gas to pass freely through the nozzle. Agita¬ tion and refinement of the molten metal can now take place. The cross-sectional area of the nozzle tube
2 orifice is suitably from 0.2 to 15mm , preferably from
2
1.0 to 5.0 mm . When the nozzle is clear, i.e. un-
35 blocked, the gas pressure will suitably lie in a range of from 5 to 250 bars, preferably from 10 to 50 bars. It will be understand from the aforegoing that when using nozzles to deliver a purging gas to molten metal contained in a ladle, the nozzle will become blocked by the molten metal which is drawn into the nozzle immedi- ately the supply of gas is cut-off, by closing the gas- flow control valve, this molten metal freezing on the nozzle walls and forming a solid plug. In accordance with the invention, when the valve is opened to allow pressurized gas to flow from the gas container an elec- trie current is, at the same time, supplied to the nozzle, which subsequently becomes hot enough to melt or at least partially melt the plug.
The force of the gas entering the nozzle is then suffi¬ cient to push the plug from the nozzle and into the molten metal bath. The gas pressure and gas flow can then be adjusted to values appropriate to gas-purging purposes and also to the geometry of the container, i.e. the ladle or converter.
The arrangement also includes a monitoring means which monitors the state of gas throughflow and which func¬ tions to switch off the supply of electric current to the nozzle when gas flows freely therethrough

Claims

C L A I S
1. In the injection of pressurized gas into a molten metal bath contained in a container through the interme¬ diary of a gas-delivery nozzle, for the purpose of agitating and purging the molten metal, said nozzle being mounted on the wall or on the bottom of said container, a method for clearing said nozzle of block¬ ages that are caused by molten metal being drawn into the nozzle-throughflow passage immediately the flow of pressurized gas is cut-off and freezing on the walls of said nozzle to form a blockage, c h a r a c¬ t e r i z e d by heating the nozzle with the aid of an electric current to a temperature at which the metal blockage will at least partially melt and therewith be removed from the nozzle throughflow passage by the gas which then passes through said nozzle.
2. An arrangement for carrying out the method accord¬ ing to Claim 1, comprising a container for gas under high pressure, a molten metal container, a nozzle, and a valve which is incorporated in a conduit extending between the nozzle and the gas container, c h a r a c¬ t e r i z e d in that the nozzle is connected to a source of electric current; and in that when current is applied to the nozzle the arrangement is such as to at least partially melt any metal that may have solidified in the nozzle throughflow passage.
3. An arrangement according to Claim 2, c h a r a c - t e r i z e d in that at least a part of the nozzle is comprised of an electrically conductive material of a kind which will be heated by the current passing there¬ through.
4. An arrangement according to Claim 2 or Claim 3, c h a r a c t e r i z e d in that the nozzle carries an electric heating wire,
5. An arrangement according to Claim 4, c h a r a c¬ t e r i z e d in that the heating wire is wound around the through-flow passage of the nozzle.
6. An arrangement according to any one of the preced¬ ing Claims, c h a r a c t e r i z e d by means for switching off the supply of electric current when the gas flows freely through the nozzle.
PCT/SE1992/000103 1991-03-04 1992-02-20 A method and arrangement for purging molten metal in a container with the aid of a gas WO1992015413A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9100616-3 1991-03-04
SE9100616A SE470009B (en) 1991-03-04 1991-03-04 Method and apparatus for gas flushing metal melts in a container

Publications (1)

Publication Number Publication Date
WO1992015413A1 true WO1992015413A1 (en) 1992-09-17

Family

ID=20382038

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1992/000103 WO1992015413A1 (en) 1991-03-04 1992-02-20 A method and arrangement for purging molten metal in a container with the aid of a gas

Country Status (4)

Country Link
EP (1) EP0574479A1 (en)
AU (1) AU1350292A (en)
SE (1) SE470009B (en)
WO (1) WO1992015413A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1910707B2 (en) * 1969-03-03 1977-01-13 Neitzel, Herward, 5657 Haan FLOOR SLIDER CLOSURE FOR THE POINT OF POTS CONTAINING METAL MELT AND METHOD OF OPERATING THE SAME
EP0329645A1 (en) * 1988-02-19 1989-08-23 Veitscher Magnesitwerke-Actien-Gesellschaft Gas bubbling plug
EP0379647A2 (en) * 1988-12-19 1990-08-01 Didier-Werke Ag Refractory nozzle and induction coil therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1910707B2 (en) * 1969-03-03 1977-01-13 Neitzel, Herward, 5657 Haan FLOOR SLIDER CLOSURE FOR THE POINT OF POTS CONTAINING METAL MELT AND METHOD OF OPERATING THE SAME
EP0329645A1 (en) * 1988-02-19 1989-08-23 Veitscher Magnesitwerke-Actien-Gesellschaft Gas bubbling plug
EP0379647A2 (en) * 1988-12-19 1990-08-01 Didier-Werke Ag Refractory nozzle and induction coil therefor

Also Published As

Publication number Publication date
AU1350292A (en) 1992-10-06
SE9100616D0 (en) 1991-03-04
SE470009B (en) 1993-10-25
EP0574479A1 (en) 1993-12-22
SE9100616L (en) 1992-09-05

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