US3729097A - Filtration of molten metal - Google Patents

Filtration of molten metal Download PDF

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Publication number
US3729097A
US3729097A US00128876A US3729097DA US3729097A US 3729097 A US3729097 A US 3729097A US 00128876 A US00128876 A US 00128876A US 3729097D A US3729097D A US 3729097DA US 3729097 A US3729097 A US 3729097A
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US
United States
Prior art keywords
filter
molten metal
metal
molten
ladle
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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.)
Expired - Lifetime
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US00128876A
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English (en)
Inventor
D Collins
B Gillett
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Alcan Research and Development Ltd
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Alcan Research and Development Ltd
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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
    • C22B9/02—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves
    • C22B9/023—By filtering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/01—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D39/00—Equipment for supplying molten metal in rations
    • B22D39/02—Equipment for supplying molten metal in rations having means for controlling the amount of molten metal by volume
    • B22D39/026—Equipment for supplying molten metal in rations having means for controlling the amount of molten metal by volume using a ladler
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D43/00—Mechanical cleaning, e.g. skimming of molten metals
    • B22D43/001—Retaining slag during pouring molten metal
    • B22D43/004—Retaining slag during pouring molten metal by using filtering means
    • 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 filter comprises a [52] US. Cl ..210/69, 210/71 y m de of a ma erial which is not attacked by the [51] Int. Cl. ..B01d 35/28 molten m l n i pr ided wi h one or more aper- [58] Field of Search ..210/69, 71, 72, 83, tures at or r the bottom these pe r ing 210/242 covered with filter material so that solid inclusions are removed from molten metal entering the filter body. [56] References cued 4 Claims, 2 Drawing Figures UNITED STATES PATENTS 3,654,150 4/1972 Eccles ..2lO/69 Patented April 24, 1973 3,729,097
  • the present invention relates to casting of light metals, particularly aluminum (including aluminum alloys) but also of other metals having comparably low melting points, such as magnesium and its alloys.
  • the present invention relates to a method of filtering molten metal in the production of castings.
  • the production of light metal castings, other than pressure die castings, is essentially a manual operation, in which molten metal is withdrawn from a holding furnace by means of a ladle. Large quantities of internal combustion engine pistons are produced by pouring molten aluminum alloy by means of a hand-held ladle into permanent steel moulds. In producing this class of gravity die-castings molten metal is taken from the holding furnace in a quantity measured only by the operators eye and any surplus in'the ladle is returned to the holding furnace before refilling the ladle for the next casting operation.
  • Piston castings for example, are machined. Any inclusions of hard aluminum oxide are very objectionable both for the wear imposed on the cutting tools during machining and for the likely wear on the cylinder surfaces from any hard oxide exposed on the cylindrical outer surface of the piston. In the production of aluminum alloy piston castings .by normal production methods, a significant proportion of the castings are rejected for this reason.
  • a glass cloth bag has been found to be a particularly suitable medium for the removal of solids, such as aluminum oxide, in this context.
  • the metal In the production of aluminum alloy castings the metal is melted in a large capacity melting furnace from which it is transferred to a number of small holding furnaces, from which one or occasionally more operators may draw molten metal by means of a ladle.
  • the aluminum oxide dross is mainly produced in the melting furnace and during pouring from the melting furnace into the holding furnace, but does not arise to any significant extent in the holding furnace.
  • Such oxide dross as is produced in the holding furnace is in the form of a very fine film. Filtration of the metal in the holding fur nace should therefore very largely obviate the introduction of oxide, particularly in the form of large hard grains, into the castings.
  • filter fixtures of various kinds have required periodic vertical adjustment to take account of variation in the metal level in the furnace or have retarded removal of metal from the furnace when the metal level is low. Such filter fixtures have thus reduced the rate of production attainable by the operator and have thus not been generally adopted in the production of aluminum alloy castings. It has already been proposed to filter aluminum in a holding furnace by means of a crucible which is supported by a framework extending across the mouth of the furnace. Metal enters the crucible through apertures in the bottom and rises through a bed of granular filter material.
  • the disadvantage of that type of filtering device is that the level of metal in the crucible is dependent upon the level of molten metal in the holding furnace with the result that a decrease in metal level also results in a drop in the metal level in the crucible with resultant difficulty in withdrawal of molten metal in a ladle.
  • the crucible was held on a variable support for height adjustment. Since in such arrangement the support extends downwardly into the furnace from above it causes obstruction in the accessibility of the pool of metal in the filter to the ladle.
  • the filter body is arranged as a free floating unit in the holding furnace.
  • the most suitable material for the construction of a floating filter body for filtering molten aluminum is plumbago (graphite) which is sub stantially unaffected by molten aluminum and has an appropriate density, that is to say somewhat less than the density of molten aluminum.
  • plumbago graphite
  • any other material which can resist molten aluminum and has a density in the range of 1.5 2.5 would be suitable for the purpose of filtering molten aluminum and indeed some material of lower density may be employed in some circumstances.
  • the width and depth of the pool of molten metal within the filter must be sufficient to permit substantially unimpeded removal of metal in the ladle.
  • the height of the filter body above the metal level must be kept small so as to avoid obstruction of the handling of the ladle by the operator.
  • the filter must be arranged so that it is fairly stable and not easily overturned by accidental contact with the ladle, which would result in the admission of unfiltered metal into the pool of metal within the filter body. In general it is preferred that the mouth diameter of the mouth of the filter body be in excess of its depth.
  • FIG. 1 illustrates one form of filter for carrying out the method of the present invention.
  • FIG. 2 illustrates a second form of filter for carrying out the method of the invention.
  • FIGS. l and 2 a body 1 of molten aluminum alloy is maintained in a holding furnace 2, which is heated by gas burners 3.
  • the holding furnace 2 is shown greatly reduced in size and in practical operation it would be substantially larger in diameter than the filters 4 and 4'.
  • the filter 4 shown in FIG. 1 comprises a cylindrical body 5 having an outwardly extending peripheral flange 6.
  • a shallow groove 7 is formed in the wall of the cylindrical body 5 near the bottom end of the filter body 4. This permits a layer of glass cloth 8 to be secured across the open bottom end of the body 5 by means of a glass binder thread 9.
  • the body 5 is formed of dense graphite of a density around 2.5 but may be formed of other material which is substantially unaffected by molten aluminum, provided that such material is less dense than molten aluminum.
  • the weight of the filter body can be increased by means of an iron ring embedded in the graphite so as to be protected from contact by molten aluminum to sink the filter 4 further into the aluminum, but this is not usually necessary.
  • metal is removed from the pool of mo]- ten metal within the filter 4 by means of a ladle 10. This reduces the level of the metal in the filter and the body 5 rises in the body 1 of metal. Metal then rises through the glass cloth 8 to restore the level of the metal in the filter body with that of the body 1. Any grains of oxide or other solid in the metal are removed by the filtering action of the glass cloth 8. As the filter body rises in the metal as the result of the removal of a ladle full of molten metal, there is some tendency for the solid grains to be shaken off the glass cloth and thus the filter has some self-cleaning tendency.
  • FIG. 2 An alternative form of floating filter 4' is shown in FIG. 2.
  • the floating filter 4 takes the form of a graphite crucible with a series of apertures 11 formed in the bottom of it.
  • a bed 12 of granular filter material is supported in the bottom of the filter and performs the same function as the glass cloth 8.
  • the bed 12 is preferably trapped beneath in a perforated disc (not shown).
  • the floating filter of FIG. 1 is the preferred arrangement, both because metal removed in the ladle is more quickly replaced through the glass cloth and because the filter body is more inherently stable and is very difficult to upset by contact with the ladle.
  • the layer of glass cloth is very easy to replace.
  • a method of filtering metal in the production of castings comprising placing a freely floating filter member in a body of molten metal, said filter member having an open top and an imperforate side wall formed of a material, which is substantially unaffected by the molten metal, while permitting molten metal to enter the filter member at the bottom end thereof through a filter medium associated with said bottom end, so that said molten metal rises from below the level of said body and only through said filter medium to form a pool in said member, said filter member allowing sufficient width and depth of said pool formed by said rise of filtered molten metal within said member, to permit substantially unimpeded removal of metal in a ladle, and withdrawing molten metal through the top of said filter member by inserting a ladle into submergence in said pool and removing the filled ladle through said top of the member, and thus causing further molten metal to rise into said filter member through said filter medium from the body of molten metal.
  • a method according to claim 2 in which the pool of molten metal is formed in essentially cylindrical shape by containment in said side wall of essentially cylindrical form, said molten metal being filtered by rising through glass cloth constituting said filter medium closing said bottom end of the filter member.
  • a method according to claim 3 which includes stabilizing the floating of said member by providing outward support in the molten metal, around the mouth of the member, with a peripheral flange.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US00128876A 1970-04-01 1971-03-29 Filtration of molten metal Expired - Lifetime US3729097A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1553670 1970-04-01

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US3729097A true US3729097A (en) 1973-04-24

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US (1) US3729097A (enrdf_load_stackoverflow)
CA (1) CA934170A (enrdf_load_stackoverflow)
GB (1) GB1342732A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4113241A (en) * 1977-09-22 1978-09-12 Swiss Aluminium Ltd. Apparatus for the filtration of molten metal in a crucible type furnace
US4124506A (en) * 1977-09-22 1978-11-07 Swiss Aluminium Ltd. Method for the filtration of molten metal in a crucible type furnace
US4394271A (en) * 1981-04-23 1983-07-19 Groteke Daniel E Apparatus and method for filtration of molten metal
DE9014187U1 (de) * 1990-10-12 1991-01-03 Kirchmeier, Hans, 5067 Kürten Filter für Flüssigmetalle
US5129998A (en) * 1991-05-20 1992-07-14 Reynolds Metals Company Refractory hard metal shapes for aluminum production
US6270717B1 (en) * 1998-03-04 2001-08-07 Les Produits Industriels De Haute Temperature Pyrotek Inc. Molten metal filtration and distribution device and method for manufacturing the same
US20040084172A1 (en) * 1999-08-05 2004-05-06 Pyrotek Engineering Materials Limited Distributor for use in metal casting
CN104289020A (zh) * 2014-10-09 2015-01-21 宜兴市锦桢铸造材料有限公司 一种汤勺过滤器
CN105886789A (zh) * 2016-06-03 2016-08-24 北京科技大学 一种超重力过滤复合净化铝及铝合金熔体的方法
CN106256913A (zh) * 2016-06-27 2016-12-28 百色学院 一种液态金属回路用熔化罐

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US444500A (en) * 1891-01-13 Jfsjfj
US763325A (en) * 1903-09-04 1904-06-21 George A Hancock Floating water-filter.
US2373320A (en) * 1940-11-12 1945-04-10 Gen Motors Corp Electrolytic reduction of aluminum bromide
US2913117A (en) * 1958-01-13 1959-11-17 G & S Metal Products Floating skimmer
US3478878A (en) * 1966-11-18 1969-11-18 Storm Products Co Soldering apparatus
US3654150A (en) * 1969-08-08 1972-04-04 Alcan Res & Dev Method for filtering molten metal

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US444500A (en) * 1891-01-13 Jfsjfj
US763325A (en) * 1903-09-04 1904-06-21 George A Hancock Floating water-filter.
US2373320A (en) * 1940-11-12 1945-04-10 Gen Motors Corp Electrolytic reduction of aluminum bromide
US2913117A (en) * 1958-01-13 1959-11-17 G & S Metal Products Floating skimmer
US3478878A (en) * 1966-11-18 1969-11-18 Storm Products Co Soldering apparatus
US3654150A (en) * 1969-08-08 1972-04-04 Alcan Res & Dev Method for filtering molten metal

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4113241A (en) * 1977-09-22 1978-09-12 Swiss Aluminium Ltd. Apparatus for the filtration of molten metal in a crucible type furnace
US4124506A (en) * 1977-09-22 1978-11-07 Swiss Aluminium Ltd. Method for the filtration of molten metal in a crucible type furnace
DE2838504A1 (de) * 1977-09-22 1979-04-05 Alusuisse Vorrichtung zum filtrieren von geschmolzenem metall
US4394271A (en) * 1981-04-23 1983-07-19 Groteke Daniel E Apparatus and method for filtration of molten metal
DE9014187U1 (de) * 1990-10-12 1991-01-03 Kirchmeier, Hans, 5067 Kürten Filter für Flüssigmetalle
US5129998A (en) * 1991-05-20 1992-07-14 Reynolds Metals Company Refractory hard metal shapes for aluminum production
US6270717B1 (en) * 1998-03-04 2001-08-07 Les Produits Industriels De Haute Temperature Pyrotek Inc. Molten metal filtration and distribution device and method for manufacturing the same
US20040084172A1 (en) * 1999-08-05 2004-05-06 Pyrotek Engineering Materials Limited Distributor for use in metal casting
US7036555B1 (en) 1999-08-05 2006-05-02 Pyrotek Engineering Materials Limited Distributor device for use in metal casting
US7131482B2 (en) 1999-08-05 2006-11-07 Pyrotek Engineering Materials Limited Distributor device for use in metal casting
CN104289020A (zh) * 2014-10-09 2015-01-21 宜兴市锦桢铸造材料有限公司 一种汤勺过滤器
CN105886789A (zh) * 2016-06-03 2016-08-24 北京科技大学 一种超重力过滤复合净化铝及铝合金熔体的方法
CN106256913A (zh) * 2016-06-27 2016-12-28 百色学院 一种液态金属回路用熔化罐
CN106256913B (zh) * 2016-06-27 2019-03-26 百色学院 一种液态金属回路用熔化罐

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Publication number Publication date
CA934170A (en) 1973-09-25
GB1342732A (enrdf_load_stackoverflow) 1974-01-03

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