EP0421990A1 - Entrainement d'un gaz de lavage a travers un bain de fusion s'ecoulant dans une poche de coulee - Google Patents

Entrainement d'un gaz de lavage a travers un bain de fusion s'ecoulant dans une poche de coulee

Info

Publication number
EP0421990A1
EP0421990A1 EP88906850A EP88906850A EP0421990A1 EP 0421990 A1 EP0421990 A1 EP 0421990A1 EP 88906850 A EP88906850 A EP 88906850A EP 88906850 A EP88906850 A EP 88906850A EP 0421990 A1 EP0421990 A1 EP 0421990A1
Authority
EP
European Patent Office
Prior art keywords
nozzle
gas
melt
pressure
ladle
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP88906850A
Other languages
German (de)
English (en)
Inventor
Mikael Brunner
Henrik Gripenberg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde Sverige AB
Original Assignee
AGA AB
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 AGA AB filed Critical AGA AB
Publication of EP0421990A1 publication Critical patent/EP0421990A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • B22D1/002—Treatment with gases
    • B22D1/005—Injection assemblies therefor

Definitions

  • the present invention relates to a method for scavenging gas through a melt in a ladle during the processing stage, the gas being supplied through a nozzle device disposed beneath the surface of the ladle bath, and for keeping the nozzle device free of melt during the charging, transport and casting phases.
  • scavenging stones have hitherto been employed in the art for supplying the gas.
  • a scaven ⁇ ging stone consists of a porous body of ceramic material. The poro ⁇ sity of the material may be of such a nature as to permit the pas ⁇ sage of gas while the melt cannot permeate through the pores.
  • scavenging stones is fraught with a number of drawbacks.
  • the scavenging stone may, in ad ⁇ dition, become blocked by the adhesion of metal or slag.
  • the steel may also break out through the stone.
  • the permitted gas pressure is limited, since excessively high gas pressure may destroy the scavenging stone. This drawback limits the gas flow which may be possible.
  • the scavenging stone suffers from a poor degree of flexibility in respect of the employment of different gas flows.
  • the object of the present invention is to obviate the above- outlined drawbacks inherent in the employment of scavenging stones and to solve the problem of opening and closing of nozzles in ladles.
  • the present invention is substantially characterised in that the nozzle device is, by the intermediary of a switchable valve ar ⁇ rangement, connected to a gas supply source of variable gas pressure which causes the nozzle device to assume one open and one substan ⁇ tially closed position, such that the nozzle, at low gas pressure, allows the passage of a gas flow which is sufficient to keep the nozzle free of the melt but is insufficient to influence the melt proper, and, at high gas pressure, allows the passage of a gas flow of such a magnitude that agitation and refining of the melt take place.
  • the present invention is further characterised in that the noz ⁇ zle device is of a cross-sectional area in the range of between 0.2 and 15 mm 2 ; that the differential pressure in a substantially closed nozzle, i.e. the difference between the gas pressure in the nozzle and the ferros atic pressure from the melt, is greater than 0.05 bar; and that the differential pressure in an open nozzle lies in the range of between 5 and 250 bar.
  • the cross-sectional area lies in the range of between 0.1 and 5.0 mm 2 and the differential pressure for an open nozzle is in the range of between 10 and 50 bar.
  • a ladle 1 is shown with a melt 2.
  • a nozzle device 3 for scavenging the melt.
  • a three-way valve 4 is disposed at the ladle 1 and is connected to the nozzle device 3 and to quick-coupling devices 5 to which conduits from gas supply equipment 6 and 7, respectively, may be connected.
  • the nozzle is opened and closed by variable gas pressures. Closure is obtained at low pressure when the nozzle merely allows the passage of a very slight gas flow. However, this flow is of sufficient magnitude to keep the nozzle free of melt but is insufficient to influence the melt proper.
  • the pressure is raised, the nozzle allows the passage of a desired gas volume for the contemplated process.
  • the pressure is once again reduced and the nozzle closes.
  • This opening and closing effect in the nozzle is attained by combining a nozzle of slight inner diameter and a gas supply system which allows for both low and high gas pressures. Two examples are given below of different nozzle cross-sectional areas.
  • the differential pressure is, here, taken to mean the difference between the pressure at the nozzle and the ferrostatic pressure from the melt.
  • the nozzle is open. If a lower gas flow is required for the processing, a lower operational pressure is selected. Hence, an optimum gas flow may be set for each ladle size and process involved, by selecting nozzle cross-sectional area and gas pressure. At 0.1 bar, the nozzle gives such a slight flow that it is, to all intents and purposes, closed.
  • differential pressure is taken to mean the difference between the pressure at the nozzle and the fer ⁇ rostatic pressure from the melt.
  • One basic pre-condition for the scavenging system according to the present invention is that a gas flow be always maintained through the nozzle, when the melt is charged into the ladle, which entails that gas must be supplied during the charging, during the transport of the ladle and during the casting process itself. This feature is made possible by the employment of the above-mentioned three-way valve 4 which is disposed on the ladle 1. Through the valve, gas supply to the nozzle device 3 may be effected from dif ⁇ ferent gas supply equipment units.
  • a stationary gas supply network 7 is connected, by the intermediary of the quick coupling devices 5, to the valve 4.
  • the conduit from the network 7 is disconnected and, in ⁇ stead, the nozzle 3 is supplied via the valve 4 from a mobile gas supply unit which accompanies the ladle during its travel.
  • a moving gas hose which supplies the nozzle with gas during transport.
  • the nozzle is then connected, by the intermediary of the three-way valve and an available quick coupling, back to a stationary gas supply network.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

Le procédé décrit sert à entraîner un gaz de lavage à travers un bain de fusion s'écoulant dans une poche de coulée au moyen d'une buse disposée dans le fond de la poche de coulée. En faisant varrier la pression du gaz, on peut placer la buse dans une position ouverte et dans une position sensiblement fermée. A une pression de gaz faible, la buse permet le passage d'un courant de gaz de quantité suffisante pour empêcher le bain de fusion d'obstruer la buse mais de quantité insuffisante pour influencer le bain de fusion à proprement parler. A une pression de gaz élevée, la buse permet le passage d'un courant de gaz d'une amplitude telle que l'agitation et le raffinage du bain de fusion se produisent. L'ordre de grandeur de la section transversale de la buse est, dans ce cas, compris entre 0,2 et 15 mm2. La pression différentielle au moment où la buse est en position sensiblement fermée, c'est-à-dire la différence entre la pression du gaz dans la buse et la pression ferrostatique provenant du bain de fusion, est supérieure à 0,05 bar et la pression différentielle au moment où la buse est en position ouverte est comprise entre 5 et 250 bars.
EP88906850A 1987-06-05 1988-06-28 Entrainement d'un gaz de lavage a travers un bain de fusion s'ecoulant dans une poche de coulee Withdrawn EP0421990A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8702338A SE8702338L (sv) 1987-06-05 1987-06-05 Gasspolning av smaelta i skaenk
PCT/SE1988/000356 WO1990000242A1 (fr) 1987-06-05 1988-06-28 Entrainement d'un gaz de lavage a travers un bain de fusion s'ecoulant dans une poche de coulee

Publications (1)

Publication Number Publication Date
EP0421990A1 true EP0421990A1 (fr) 1991-04-17

Family

ID=26659836

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88906850A Withdrawn EP0421990A1 (fr) 1987-06-05 1988-06-28 Entrainement d'un gaz de lavage a travers un bain de fusion s'ecoulant dans une poche de coulee

Country Status (6)

Country Link
EP (1) EP0421990A1 (fr)
DK (1) DK307190D0 (fr)
FI (1) FI906412A7 (fr)
NO (1) NO905600D0 (fr)
SE (1) SE8702338L (fr)
WO (1) WO1990000242A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895785A (en) * 1972-08-01 1975-07-22 United States Steel Corp Method and apparatus for controlling the operation of a steel refining converter
FR2473064A1 (fr) * 1980-01-02 1981-07-10 Siderurgie Fse Inst Rech Procede de brassage pneumatique d'un bain de metal en fusion
JPS5757817A (en) * 1980-09-19 1982-04-07 Kawasaki Steel Corp Method for controlling bottom blowing gas in steel making by composite top and bottom blown converter
JPS57143421A (en) * 1981-02-27 1982-09-04 Nippon Steel Corp Switching method for bottom blowing gas
FR2501722B1 (fr) * 1981-03-11 1986-08-14 Siderurgie Fse Inst Rech Procede de brassage pneumatique d'un bain metallique

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9000242A1 *

Also Published As

Publication number Publication date
NO905600L (no) 1990-12-27
NO905600D0 (no) 1990-12-27
SE8702338L (sv) 1988-12-06
SE8702338D0 (sv) 1987-06-05
FI906412A0 (fi) 1990-12-27
DK307190A (da) 1990-12-28
FI906412A7 (fi) 1990-12-27
DK307190D0 (da) 1990-12-28
WO1990000242A1 (fr) 1990-01-11

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