US3689046A - Apparatus for purifying metallic melts in a vacuum - Google Patents

Apparatus for purifying metallic melts in a vacuum Download PDF

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Publication number
US3689046A
US3689046A US3689046DA US3689046A US 3689046 A US3689046 A US 3689046A US 3689046D A US3689046D A US 3689046DA US 3689046 A US3689046 A US 3689046A
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United States
Prior art keywords
melt
degassing
chambers
container
vacuum
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Expired - Lifetime
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English (en)
Inventor
Edouard De Bie
Boris Tougarinoff
Franz Sperner
Justus Moll
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Societe Generale Metallurgique de Hoboken SA
Leybold Heraeus Verwaltung GmbH
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Leybold Heraeus Verwaltung GmbH
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention relates to a method and apparatus for purifying metallic melts and of degassing them in a vacuum. It applies particularly to melts of copper, wherein the melt is fed continuously from a container for the molten bath by means of a barometric intake pipe to a device for vacuum treatment located above the melt, and which thereafter flows back to the same molten bath container through a barometric discharge pipe. Copper must be thoroughly degassed, since traces of oxygen would decrease electrical conductivity. In other words, copper is a very critical material which is a subject of the invention.
  • the known methods are all based on a relatively rapid passage of the melt through the single degassing chamber. This causes the disadvantage of poor or no degassing of the lower layers of the metal flowing from the barometric intake pipe to the discharge pipe because of inadequate mixing and of the small surface area of the melt which it is desired to degass. It is an additional disadvantage of the known methods that there are no provisions for purifying the melts of foreign bodies and slags which are present in the solid or liquid states. Failure to comply with the last mentioned requirement may not have overly serious consequences in steel melts for which the known methods are primarily intended, but causes an unacceptable deterioration of the material in the production of high-purity copper.
  • a two-stage method for degassing metals disclosed in US. Pat. No. 3,367,396 causes a portion of the metal to be led in a cyclic path, the pressure decreasing in the direction of flow, but the second stage employs the socalled pouring stream degassing method.
  • the latter method requires a certain drop, and therefore a spatial separation of the two degassing stages. This makes it impossible to build a compact apparatus so that heat losses through the large surface are substantial even when good thermal insulation is employed, and are not tolerable for an extended use of the degassing process.
  • the pouring stream degassing method has the disadvantage of a short dwell time so that the complete removal of all gases from the melt is not always possible.
  • the object of the invention is the avoidance of the disadvantages resulting from the known methods, and particularly the provision of a method for copper purification which results in a totally degassed ultimate product of high purity.
  • This object is achieved by the invention by performing the degassing operation in at least two degassing chambers adapted to be separately evacuated and located on the same level, the two chambers being passed sequentially by the stream of molten metal and sealed from each other by the metal against transfer of gas therebetween.
  • This arrangement has the advantage that a much higher vacuum can be reached in the second chamber because of the absence of conveying gas, and that the molten metal can be purified simultaneously in the second chamber of particles of foreign matter and of slag in the solid or liquid state.
  • the power requirements and dimensions of the pumping units are held within tolerable limits. It is possible not only to reach a higher vacuum in the second chamber, but also, depending on the capacity of the chamber to achieve an adequate dwell time for the melt.
  • the arrangement of the chambers on a common level results in the particular advantage of a compact structure because both chambers can be enclosed in a common insulating shell. Also, the heat losses are greatly reduced thereby.
  • a preferred apparatus for performing the method is arranged in such a manner that the device for vacuum' treatment consists of two degassing chambers separated by a partition wall, a liquid seal being interposed between the chambers and filled with the molten metal, each of the chambers communicating with a barometric pipe which is immersed in the melt to be degassed.
  • an inclined, step or wave shaped flow area for the molten metal is preferably provided with the second degassing chamber.
  • degassing chambers as well as the barometric pipes may be arranged substantially concentrically, the liquid seal being annular.
  • the first, inner degassing chamber is enveloped by the second, outer chamber. Because of the greater radius of the second chamber, it s possible to provide there not only a longer flow path for the molten metal, but also a larger volume so that an optimal dwell time for the melt can be adjusted. Moreover, there is achieved a particularly simple design of the apparatus with a minimum of thermal losses. Because the basic elements have rotational symmetry, there is obtained an apparatus of increased mechanical strength.
  • the inner barometric pipe is preferably employed as the suction pipe, and its upper end is provided with a dish shaped enlargement having an annular groove offset from its outer circumference, the groove jointly with the partition of hollow cylindrical shape bounding the space for the liquid seal.
  • the dish shaped enlargement constitutes a so-called downflow skirt for the melt, the surface of the melt being enlarged particularly at the outer rim of the skirt, and the release of gas from the melt being greatly facilitated by the formation of a film having two exposed surfaces as the melt runs off the rim.
  • FIGS. 1 to 4 show:
  • FIG. 1 l is a sectional view of the embodiment of the invention showing a melt container with different superimposed degassing devices;
  • FIG. 2 is a sectional view of a modification of the embodiment shown in FIG. 1;
  • FIG. 3 is a section of a device with several sequentially arranged degassing devices according to FIG. 1 or FIG. 2;
  • FIG. 4 is a schematic representation of a device with several degassing devices according to FIG. 1 or FIG. 2, arranged in parallel.
  • FIG. 1 shows a melt container 1 which is a warming furnace to keep the melt warm. It is equipped with an induction heater 2 for the molten metal 3.
  • a degassing apparatus generally indicated by numeral 4 is superimposed on the warming furnace. Said degassing apparatus has two degassing chambers 5,6 juxtaposed at the same level and separated from each other by an upright partition wall 7. The bottom of degassing apparatus 4 has a groove shaped recess 8 partly engaged by a partition 7 extending thereinto. The cooperation of these two structural features will be described in more detail below.
  • the upper ends of the degassing chambers 5,6 are connected to vacuum lines 9,10, which lead to separate pumps or sets of pumps, not shown.
  • a barometric suction conductor pipe 11 terminates in the bottom portion of the degassing chamber 5, while the bottom portion of degassing chamber 6 leads to the barometric discharge pipe 12. Moreover, a supply line 13 for injecting a conveying gas inert to metal, such as nitrogen, into the metal melt, leads into the barometric feed pipe 11. An additional settling space 14 is provided between degassing chamber 6 and barometric discharge pipe 12.
  • liquid separators 17,18 arranged in front of or below the orifices of the lines have the shapes of plates about which gas may freely flow.
  • the melt container as well as the degassing apparatus 4 are provided with a lining 19 which consists of graphite or a graphite bearing material from which partition 7, pipes 1 1,12 and separators 17,18 are also made.
  • a metallic shell 20 With the exception of the barometric pipes, all parts of the apparatus are enveloped by a metallic shell 20.
  • a non-illustrated layer of thermally insulating material is preferably interposed between the shell and the liner 19.
  • the apparatus according to the invention operates as follows:
  • FIG. 2 there is shown a modified form of the device of FIG. 1 in which elements having the same function are designated by the same numerals, with suffix 0 added.
  • the barometric intake and discharge pipes 11a, 12a as well as the degassing chambers 5a,6a are concentric cylindrical elements in this case.
  • the central barometric intake pipe 11a is provided with a dish shaped enlargement 22 at its upper end, the enlargement being provided with an annular recess 23 spaced from the rim thereof.
  • Recess 23, jointly with the lower end of the cylindrically tubular partition wall 7a, provides the space for the liquid seal 16a.
  • the lower end of the cylindrical partition wall 7a is provided with arcuate recesses which constitute well-defined passages for the molten metal.
  • the lands of the partition 7a between the recesses rest on the dish shaped enlargement 22 in the recess 23.
  • the liquid separators 17a which are perforated plates are located within the partition and pass the entire conveying gas and a portion of the gas originally present in the metal to the vacuum line 90, and thence to the pumps.
  • the melt After passing the liquid seal 16a, the melt runs in a thin film over the flow surface 15a of the dish shaped enlargement 22, and from there into the settling space as a freely falling film 24 exposed on both sides to the vacuum in degassing chamber 6a.
  • Degassing chamber 6a communicates with vacuum line 10a and the associated pumping plant through the liquid separator 18a which is also a perforated plate.
  • the melt returns from the settling space 14a through an annular space bounded between the barometric discharge pipe 12a and the barometric intake pipe 110.
  • Barometric discharge pipe 12a is provided at its lower end with a bottom 25 in which the lower end of the intake pipe 11a is inserted in a liquidtight engagement.
  • the metal melt therefore must leave the barometric discharge pipe 12a through radial discharge openings 26.
  • Said discharge openings 26 are not located too closely adjacent the intake opening of the barometric intake pipe 11a, but it is immaterial whether a portion of the circulating melt is'again drawn into the intake pipe immediately after leaving the discharge pipe because a high rate of circulation of the melt is beneficial in causing the entire contents of the melt container la to participate in a short period in the purification process in the degassing device 4a.
  • Heat losses from degassing device 4a are reduced by special heat insulation 21 which may consist of glass wool, rock wool or graphite wool, and which in turn is surrounded by a metallic shell 20.
  • the degassing apparatus and the operating personnel are additionally protected by a radiation protection device 27 comprising several sheet metal shields.
  • the method and apparatus of the invention are eminently suitable for intermittent operation, that is, for the degassing of a batch located in a melt container, as well as for continuous operation.
  • the degassing apparatus communicates with a continuously operating melting plant and also with a continuously operating apparatus for the casting of continuous billets or ingots.
  • a continuously operating installation is diagramatically illustrated in FIG. 3.
  • Three melt containers la, 1b, I I c, are provided with respective superposed degassing devices 40, 4b, 4c and are arranged in series.
  • the first melt container communicates with the continuously operating melting apparatus 29 by way of a trough 28.
  • the last melt container supplies a continuously operating billet or ingot casting plant 31 through control valves 30.
  • the molten metal 3 flows from a preceding melt container over an overflow 32 to the subsequent melt container.
  • the arrangement of FIG. 3 is employed if the ultimate product is required to be a metal of extreme purity and freedom from gases. It is possible to closely approach the theoretical limit of purity if an oxidizing gas such as air, oxygen and/or chlorine or chlorine compounds are fed to the first stage in the melt container 1a and/or in the degassing device 40 together with the conveying gas.
  • the oxidizing gases facilitate the removal of such impurities as lead, arsenic, antimony, selenium, tellurium and sulfur down to an amount of 1 part per million or less.
  • the second stage (1b to 4b) is supplied with a reducing gas, such as hydrogen, carbon monoxide, a hydrocarbon and/or chlorine or a chlorine compound which permits a metal to be obtained completely free from oxygen.
  • a reducing gas such as hydrogen, carbon monoxide, a hydrocarbon and/or chlorine or a chlorine compound which permits a metal to be obtained completely free from oxygen.
  • the metal is mixed with a neutral gas, such as nitrogen, to remove all residual gases present other than oxygen. Casting may then follow.
  • FIG. 4 diagrammatically illustrates a parallel arrangement of three melt containers 1a,lb,1c with superposed degassing devices 4a,4b,4c.-
  • This arrangement permits a fully continuous operation, degassing being performed in one of the devices while casting and/or supplying the metal to be purified takes place in the other one.
  • the arrangement of FIG. 4 further permits subjecting the metal in the several melt containers and/or the associated degassing devices to various chemical treatments or reactions, the several portions of the melt so treated being led together and mixed prior to pouring into molds. It is possible, for example, to modify the treatment by introducing first an oxidizing agent and subsequently a reducing agent into the one device or to proceed in the opposite sequence as described above. This permits obtaining an ultimate product of desired specific properties.
  • FIGS. 3 and 4 do not exhaust the possible combinations of individual degassing devices. It is entirely possible in certain cases only two melt containers with superposed degassing devices may be required for achieving a pure metal or specific properties. On the other hand, combinations of four or more sets, and combinations of series-arranged and parallel sets are also possible. Obviously, the method of the invention is applicable not only to a continuous casting process, but also to the casting of individual shapes.
  • Apparatus for purifying and degassing molten metals by vacuum comprising, in combination, a melt container; a device located above the melt for vacuum treating said melt; means for continuously feeding said melt from said container to said device by a conveying gas; barometric intake pipe means communicating with said melt container for passing said melt from said container to said device; barometric discharge pipe means communicating with said melt container for returning said melt to said container after vacuum treatment by said device; and two degassing chambers in said vacuum device located on a common level and being separately evacutable, said two chambers being passed in sequence by the flowing melt and being sealed gastight from each other by said melt, said melt forming an annular liquid seal between said chambers, said degassing chambers being substantially concentric with said barometric pipe means.
  • Apparatus according to claim 1 wherein the inner barometric pipe serves as suction pipe and is provided at its end with a dish shaped enlargement having an annular recess spaced from the rim of the enlargement, the recess jointly with the lower end of the cylindrically tubular partition bounding the space for the liquid seal.
  • Apparatus according to claim 1 characterized in that several of the devices for vacuum degassing are arranged above melt containers which are arranged in series as for continuous cascading flow therethrough.
  • Apparatus according to claim 1 characterized .in that several of the devices for vacuum degassingare arranged above melt containers arranged in parallel for continuous flow therethrough.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
US3689046D 1969-03-14 1970-03-13 Apparatus for purifying metallic melts in a vacuum Expired - Lifetime US3689046A (en)

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DE19691912936 DE1912936B2 (de) 1969-03-14 1969-03-14 Vorrichtung und betriebsverfahren zum reinigen und vakuum entgasen von schmelzfluessigen metallen

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BE (1) BE744073A (de)
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4071356A (en) * 1976-11-24 1978-01-31 Nippon Steel Corporation Method for refining a molten steel in vacuum
US4241904A (en) * 1978-08-18 1980-12-30 Nippon Steel Corporation Molten-metal treating vessel
US4456478A (en) * 1982-05-07 1984-06-26 Arbed S.A. Method of and apparatus for metallurgically treating molten metals
US4612044A (en) * 1983-09-30 1986-09-16 Vacmetal Gesellschaft Fur Vakuum-Metallurgie Mbh Method of vacuum treating metal melts, and vessel for use in the method
US20030051509A1 (en) * 2001-09-14 2003-03-20 Asahi Glass Company, Limited Vacuum degassing apparatus for molten glass
US20120167633A1 (en) * 2009-03-09 2012-07-05 Norio Hirayama Glass-Melting Device for Producing Glass Fiber and Method for Producing Glass Fiber
US8689588B2 (en) 2009-03-09 2014-04-08 Nitto Boseki Co., Ltd. Glass-melting device for producing glass fiber and method for producing glass fiber using same
CN106947847A (zh) * 2017-03-25 2017-07-14 华北理工大学 一种压力循环脱气设备及其精炼钢水的方法
US11001519B2 (en) 2018-03-15 2021-05-11 Owens-Brockway Glass Container Inc. Vacuum refining of molten glass

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3906340A1 (de) * 1989-02-24 1990-08-30 Mannesmann Ag Verfahren und vorrichtung zur vakuumbehandlung von metallen

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2054922A (en) * 1933-10-12 1936-09-22 American Smelting Refining Vacuum treatment of metals
US2859262A (en) * 1955-09-05 1958-11-04 Hoerder Huettenunion Ag Apparatus for degasifying liquid metal
US3215423A (en) * 1962-08-01 1965-11-02 Pennsalt Chemicals Corp Degassing system for metal alloy furnace
US3321300A (en) * 1963-08-13 1967-05-23 Conzinc Riotinto Ltd Degassing of metals or alloys
US3342250A (en) * 1963-11-08 1967-09-19 Suedwestfalen Ag Stahlwerke Method of and apparatus for vacuum melting and teeming steel and steellike alloys
US3367396A (en) * 1965-04-05 1968-02-06 Heppenstall Co Installation for the vacuum treatment of melts, in particular steel melts, and process for its operation
US3457064A (en) * 1966-05-24 1969-07-22 Chemical Construction Corp Continuous vacuum degassing of liquids

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2054922A (en) * 1933-10-12 1936-09-22 American Smelting Refining Vacuum treatment of metals
US2859262A (en) * 1955-09-05 1958-11-04 Hoerder Huettenunion Ag Apparatus for degasifying liquid metal
US3215423A (en) * 1962-08-01 1965-11-02 Pennsalt Chemicals Corp Degassing system for metal alloy furnace
US3321300A (en) * 1963-08-13 1967-05-23 Conzinc Riotinto Ltd Degassing of metals or alloys
US3342250A (en) * 1963-11-08 1967-09-19 Suedwestfalen Ag Stahlwerke Method of and apparatus for vacuum melting and teeming steel and steellike alloys
US3367396A (en) * 1965-04-05 1968-02-06 Heppenstall Co Installation for the vacuum treatment of melts, in particular steel melts, and process for its operation
US3457064A (en) * 1966-05-24 1969-07-22 Chemical Construction Corp Continuous vacuum degassing of liquids

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4071356A (en) * 1976-11-24 1978-01-31 Nippon Steel Corporation Method for refining a molten steel in vacuum
US4241904A (en) * 1978-08-18 1980-12-30 Nippon Steel Corporation Molten-metal treating vessel
US4456478A (en) * 1982-05-07 1984-06-26 Arbed S.A. Method of and apparatus for metallurgically treating molten metals
US4612044A (en) * 1983-09-30 1986-09-16 Vacmetal Gesellschaft Fur Vakuum-Metallurgie Mbh Method of vacuum treating metal melts, and vessel for use in the method
US20030051509A1 (en) * 2001-09-14 2003-03-20 Asahi Glass Company, Limited Vacuum degassing apparatus for molten glass
US6948338B2 (en) * 2001-09-14 2005-09-27 Asahi Glass Company, Limited Vacuum degassing apparatus for molten glass
US20120167633A1 (en) * 2009-03-09 2012-07-05 Norio Hirayama Glass-Melting Device for Producing Glass Fiber and Method for Producing Glass Fiber
US8689588B2 (en) 2009-03-09 2014-04-08 Nitto Boseki Co., Ltd. Glass-melting device for producing glass fiber and method for producing glass fiber using same
US8689586B2 (en) * 2009-03-09 2014-04-08 Nitto Boseki Co., Ltd. Glass-melting device for producing glass fiber and method for producing glass fiber
CN106947847A (zh) * 2017-03-25 2017-07-14 华北理工大学 一种压力循环脱气设备及其精炼钢水的方法
CN106947847B (zh) * 2017-03-25 2019-04-30 华北理工大学 一种压力循环脱气设备及其精炼钢水的方法
US11001519B2 (en) 2018-03-15 2021-05-11 Owens-Brockway Glass Container Inc. Vacuum refining of molten glass

Also Published As

Publication number Publication date
DE1912936A1 (de) 1971-02-04
BE744073A (fr) 1970-06-15
GB1248556A (en) 1971-10-06
DE1912936B2 (de) 1971-05-19

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