US3870508A - Electroslag refining - Google Patents

Electroslag refining Download PDF

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Publication number
US3870508A
US3870508A US323320A US32332073A US3870508A US 3870508 A US3870508 A US 3870508A US 323320 A US323320 A US 323320A US 32332073 A US32332073 A US 32332073A US 3870508 A US3870508 A US 3870508A
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United States
Prior art keywords
mould
metal
refined
bath
ingot
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Expired - Lifetime
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US323320A
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English (en)
Inventor
John Barry Cartwright
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British Iron and Steel Research Association BISRA
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British Iron and Steel Research Association BISRA
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C22B9/18—Electroslag remelting

Definitions

  • Clt t t mould introducing a ompactable material into the ⁇ Si ⁇ Int. Cl C22d 7/00, B22d 27/02 annular Spacing f d between the Solid member Field of Search 75/10 EB? 13/9; and the internal mould w'alls, forming a bath of molten l64/5O- 1 l48/26 slag within the mould, passing an electric current through the slag bath to maintain the temperature of l l References Cited the bath at or above the melting point of the metal to UNITED STATES PATENTS be refined and causing droplets of unrefined metal to 3.2341108 2/1966 Peras 75/10 travel through the molten Slag bath and to Collect 3,305,923 2/1967 Zimmer 75/10 R above the member and compactable material which 3,344,839 10/1967 Sunnen 164/52 droplets form a pool of refined liquid metal which pro- 3,496t280 u e O /10 gressively solidifies to form an
  • an electricallyconductive slag within a mould is maintained in a molten state and at a temperature above the melting point of the metal to be refined.
  • Unrefined metal is introduced into the mould and is refined as it passes in droplet form through a bath of the molten slag, refined droplets collecting to form a pool beneath the slag bath.
  • the mould walls are cooled by the circulation of a coolant, normally water, and a solidified ingot is built up beneath the molten metal pool.
  • the metal to be refined may be introduced to the mould in the form of one or more consumable electrodes which extend into the upper open-end of the mould, and the slag may be maintained molten by passage of an electric current from the electrode(s) to the baseplate on which the mould stands; alternatively, the metal may be introduced in molten form or as particulate matter, for example in the form of scrap or pellets, electrical energy being supplied to the slag bath by means of one or more non-consumable electrodes or plasma torches. In each case, electrical current flows from the electrode or plasma torch, through the slag bath and solidified ingot to the mould baseplate from which it is returned to the electricity supply.
  • electroslag refining plant have hitherto incorporated baseplates having internal passages for the flow ofa coolant (normally water).
  • a coolant normally water
  • Such baseplates are expensive to construct'and suffer from the disadvantage that starting stubs cannot satisfactorily be welded to their upper surfaces.
  • electroslag refining apparatus includes a cooled mould into the open lower end of which extends a member constructed of an electrically-conductive material weldably compatible with the metal
  • the space defined between the upstanding member and the opposed wall of the mould may be filled with a compactable material, e.g. crushed used slag, which will not react with the molten slag employed during operation of the process and will permit movement of the mould relative to the formed ingot.
  • a ring of heat-resisting material e.g. asbestos, may be p0- sitioned above the crushed slag to prevent, or reduce, flow of molten slag into the space formed between the upstanding member and the mould.
  • the mould may, during operation of the process, move vertically relative to the formed ingot; in such an arrangement the space between the member and the opposed surface of the mould is sufficient to permit thermal expansion of the member without preventing movement of the mould relative to the ingot formed.
  • FIG. 1 is a sectional elevational view of electroslag refining apparatus embodying the invention.
  • FIG. 2 is a similar view of alternative electroslag refining apparatus embodying the invention.
  • the apparatus illustrated in FIG. 1 includes an openended cooled mould I mounted on and insulated from an uneooled baseplate 2 constructed of mild steel plate.
  • a consumable electrode 3 extends into the upper openend of the mould 1.
  • Welded to the upper surface of the baseplate 2 is a member 4 which extends upwardly into the lower open-end of the mould 1 and which comprises a mild steel lower portion 4a and an upper portion 41; cut from one end of the electrode 3 and welded to the lower portion.
  • the member 4 may consist entirely of a material weldably compatible with the material to be refined.
  • the annular space defined between the internal wall of the mould l and the member 4 is filled with a compactable material 5 which is substantially inert with respect to the molten slag to be employed in the process.
  • crushed used slag may be employed.
  • a ring 6 of heat-resistant material, e.g. asbestos, is placed above the material 5.
  • the area of the upper surface of the member 4 is sufficiently large to support the ingot to be formed and to carry the full working current which will, during operation, flow from the electrode 3.
  • the permissible surface area of member 4 is limited only by the fact that the volume of crushed slag between the member and the mould must be large enough to ensure that thermal expansion of the member does not exert a force on the mould wall sufficient to prevent movement of the mould relative to the baseplate.
  • the diameter of the member 4 is between two-fifths and ninetenths of the internal diameter of the mould 1. For example, in the melting of an electrode within a mould of internal diameter 12 inches, a member of 9 inches diameter is employed and the current conveyed to the molten slag from the electrode 3 is of the order of 320 KW.
  • the electrode 3 and baseplate 2 are electrically connected to a current source 7.
  • the crushed slag 5 and the asbestos ring 6 prevent molten slag from penetrating the space between the member 4 and the wall of the mould 1. It has been found that if molten slag is allowed to enter this space,
  • the member 4 can readily be removed from the ingot bottom by breaking the weldW and can be re-used with a minimum of preparation.
  • the mould comprises an ingot form ing section 1 and a lower extension piece 11 which seats upon the baseplate 2, and the crushed slag 5 is positioned between the member 4 and the internal wall of the mould extension piece 11.
  • the mould 1 remains stationary during a melt, a duct 12 being provided for admitting molten slag to the base of the mould for starting purposes and means being provided for lowering the electrode 3 as melting proceeds to maintain a pre-determined gap between the electrode tip and the surface of the molten metal pool.
  • the upper surface area of the member 4 is sufficiently large to support the ingot formed and to carry the full melting current which will, during operation, flow from the electrode 3.
  • the present invention is advantageous in that cooling of the baseplate on which the mould rests is unnecessary.
  • baseplates have been cooled (usually water-cooled) in order to prevent melting of the baseplate by the molten slag.
  • the presence of the member 4 has the effect of concentrating the working current within the central portion of the mould.
  • a method of forming an ingot of refined metal by the electroslag refining process comprising the steps of introducing into the lower open end ofa cooled mould a solid un-cooled electrically-conductive member of a material weldably compatible with the metal to be refined, the member having a surface area sufficient to conduct the full working current employed in the process but small enough to leave an annular space heneath the top of said member between its periphery and the internal walls of the mould, filling said annular space with a compactible electrically insulating material which accommodates reductions in the annular spacing caused by differential thermal expansion between the member and the lower end of the mould into which the member extends and which is readily removed from the surfaces of the member and the ingot formed following completion of the process, forming a bath of molten slag within the mould and above the member and the electrically insulating material, passing an electric current through the slag bath to maintain the temperature of the bath at or above the melting point of the metal to be refined and causing droplets of unrefined
  • the electrically insulating material comprises crushed used slag covered by a ring of heat-resistant material.
  • the mould includes a lower extension piece mounted on the steel baseplate and wherein the solid member extends upwardly into the said extension piece of the mould.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
US323320A 1972-01-27 1973-01-12 Electroslag refining Expired - Lifetime US3870508A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB388672A GB1364192A (en) 1972-01-27 1972-01-27 Electroslag refining

Publications (1)

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US3870508A true US3870508A (en) 1975-03-11

Family

ID=9766730

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US323320A Expired - Lifetime US3870508A (en) 1972-01-27 1973-01-12 Electroslag refining

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US (1) US3870508A (forum.php)
JP (1) JPS4884004A (forum.php)
DE (1) DE2303441A1 (forum.php)
FR (1) FR2169290B1 (forum.php)
GB (1) GB1364192A (forum.php)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3234608A (en) * 1959-11-19 1966-02-15 Renault Continuous-casting method of melting metals in a slag medium by using consumable electrodes
US3305923A (en) * 1964-06-09 1967-02-28 Ind Fernand Courtoy Bureau Et Methods for bonding dissimilar materials
US3344839A (en) * 1963-11-28 1967-10-03 Soudure Electr Autogene Process for obtaining a metallic mass by fusion
US3496280A (en) * 1968-08-15 1970-02-17 United States Steel Corp Method of refining steel in plasma-arc remelting
US3507968A (en) * 1968-09-26 1970-04-21 Arcos Corp Electroslag melting apparatus
US3771997A (en) * 1967-08-02 1973-11-13 Foseco Int Titanium oxides in electroslag processes

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1608227A1 (de) * 1967-02-07 1970-12-03 Ass Elect Ind Herstellung von Metallbarren nach dem Elektroschlackeverfahren

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3234608A (en) * 1959-11-19 1966-02-15 Renault Continuous-casting method of melting metals in a slag medium by using consumable electrodes
US3344839A (en) * 1963-11-28 1967-10-03 Soudure Electr Autogene Process for obtaining a metallic mass by fusion
US3305923A (en) * 1964-06-09 1967-02-28 Ind Fernand Courtoy Bureau Et Methods for bonding dissimilar materials
US3771997A (en) * 1967-08-02 1973-11-13 Foseco Int Titanium oxides in electroslag processes
US3496280A (en) * 1968-08-15 1970-02-17 United States Steel Corp Method of refining steel in plasma-arc remelting
US3507968A (en) * 1968-09-26 1970-04-21 Arcos Corp Electroslag melting apparatus

Also Published As

Publication number Publication date
FR2169290B1 (forum.php) 1976-05-14
JPS4884004A (forum.php) 1973-11-08
DE2303441A1 (de) 1973-08-02
FR2169290A1 (forum.php) 1973-09-07
GB1364192A (en) 1974-08-21

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