US3836613A - Method of making liner in an induction melting furnace - Google Patents

Method of making liner in an induction melting furnace Download PDF

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Publication number
US3836613A
US3836613A US00194949A US19494971A US3836613A US 3836613 A US3836613 A US 3836613A US 00194949 A US00194949 A US 00194949A US 19494971 A US19494971 A US 19494971A US 3836613 A US3836613 A US 3836613A
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United States
Prior art keywords
liner
furnace
refractory
composition
dry
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Expired - Lifetime
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US00194949A
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English (en)
Inventor
K Granitzki
P Schiefer
H Hess
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VFG VERTRIEBSGES fur GIESSTEC
VFG VERTRIEBSGES fur GIESSTECHNISCHE ERZEUGNISSE MBH DT
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VFG VERTRIEBSGES fur GIESSTEC
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/16—Making or repairing linings ; Increasing the durability of linings; Breaking away linings
    • F27D1/1626—Making linings by compacting a refractory mass in the space defined by a backing mould or pattern and the furnace wall
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/14—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B14/00—Crucible or pot furnaces
    • F27B14/06—Crucible or pot furnaces heated electrically, e.g. induction crucible furnaces with or without any other source of heat
    • F27B14/061—Induction furnaces

Definitions

  • a dry refractory tertiary quartzite granular composition is filled between the furnace wall and a form defining the inner shape of the liner and densified as by vibration applied to the form.
  • the form is removed to leave a selfsupporting liner.
  • the exposed inner surface of the liner is impregnated with a binder to a depth less than the total thickness of the liner to form an inner strengthened shell having a thickness of from 1-8 mm.
  • the inner shell is then sintered leaving the outer zone of said linear unsintered.
  • Induction melting furnace of the crucible and trough type are generally lined with plastic, semi-plastic and/or dry compositions having a base of a refractory metal oxide such as MgO, A1 0 SiO spinels, and the like.
  • the refractory lining is rammed up with the refractory composition, also called fritting composition, with the aid of a precisely centered sheet-metal form which creates a cavity, or the composition is poured in and vibrated.
  • the sintering agent which is usually in the form of boric acid, must be mixed in dry form with the composition.
  • Such dry compositions are rammed up or vibrated in place with the aid of a form which in this case 3,836,613 Patented Sept. 17, 1974 serves both for the transfer of the energy, e.g., by vibration to densify the loose granular mixture, and, mainly, for the purpose of giving stability to the granular mixture.
  • the object of the invention is to create a self-supporting liner which eliminates the losses involved in forms expended during construction of the liner, but provides the greatest possible protection against mechanical and thermal stresses.
  • this invention contemplates a self-supporting liner for an induction melting furnace constructed of an unsintered densified mass of a refractroy oxide or mixture of oxides having on its inside surface intergral therewith a shell consisting of the same mass but containing a binding agent which becomes stronger at elevated temperatures.
  • This invention further contemplates a method for preparing a self-supporting liner for an induction melting furnace which method comprises the steps of:
  • a self-supoprting liner for an induction furnace is made, pursuant to the present invention, by filling a form within the furnace which form defines the space to be filled. Such space when filled constitutes the liner.
  • the liner is filled with a dry refractory material, especially a refractory material of the tertiary quartzite type having a grain configuration of round to cubic.
  • the refractory material is in admixture with a sintering agent, desirably dry boric acid.
  • Vibrational energy is applied to the so-filled form. This energy effects compacting the loose granular mixture to a dense mass and provides stability to the granular mixture.
  • binding agent which becomes stronger at elevated temperatures.
  • binding agents include phosphate binding agents especially monoaluminum phosphate and derivatives thereof containing phosphorus.
  • the binding agents effect is to impart durability and mechanical strength to the liner before and when being sintered. While the amount of binding agent can vary over a wide range, a quantity between 0.05 and 0.07 cubic centimeters of binding agent per square centimeter of surface area treated is enough. Generally spoken, the quantity of binder suffices which is sucked in by the dry liner material on the inside surface.
  • the inside wall is subjected to a temperature between 400 and 700 C. to effect strengthening the inner shell of the wall and to provide the same with good mechanical properties.
  • a self-supporting liner comprising, on the coil side exclusively, a highly compacted, dry granular structure of refractory oxide or oxide mixture to which a dry sintering agent, preferably boric acid, has been added is provided.
  • the inner surface layer of said liner has an integral shell comprising a binding agent which becomes stronger at elevated temperatures which has been subjected to elevated temperatures.
  • the thickness of the strengthened shell is preferably provided by applying to the inner surface layer a binding agent especially a phosphate binding agent, particularly a monoaluminum phosphate binder with variable phosphate members.
  • a binding agent especially a phosphate binding agent, particularly a monoaluminum phosphate binder with variable phosphate members.
  • suitable binders include, for example, sodium silicates of varying soda to silica ratio (such as water glass), silicic acid esters, tar, dextrine solutions, and sulfite waste liquor.
  • the preferred starting material for these refractory compositions are quartzites having a tertiary quartzite base, since they have a round to cubic grain which is particularly well suited for dense packing. These quartzites are fine to coarsely crystalline in their mineralogical nature, and they may or may not contain a binding agent, for example, the so-called basal cement.
  • FIG. 1 is a graph summarizing the eifect of temperature of expansion for three different compositions.
  • FIG. 2 shows the grain size and configuration of re fractory metals used in the liner of the present invention.
  • FIG. 3 is a cross-sectional diagram showing a liner, form and furnace during construction.
  • FIG. 1 shows the expansion characteristics of the compositions as a percentage, in relation to the temperature in C.
  • the three compositions show a like expansion up to about C., but above this temperature they differ, in that Composition B tends to shrink while Composition A and Composition C have an expansion of just under 9% at about 1600 C.
  • the invention utilizes these expansion characteristics, and it is pointed out that in crucible furnaces the refractory liner is an annular body which in the case of expansion, due to the effect of temperature, for example, can only increase in diameter.
  • the thermal expansion characteristics be adjusted on the basis of the mineralogy of the refractory liner, preferably tertiary quartzite, and on the basis of the amount of sintering agent used, in such a manner that in the 1600 C. temperature range, and with a sintering agent content of 1%, an expansion of the refrac tory composition of 7 to 9% will be achieved.
  • Example A is best performed by a liner having a tertiary quartzite base material with round to cubic grain form.
  • the grain form can be produced by appropriate precessing of the very hard rock.
  • the tertiary quartzite with a basal cement structure, which is used here, is substantially harder than a rock quartzite.
  • the least suitable grain form is also shown in FIG. 2, and is marked B. It is a grain form existing preferably in crushed rock quartzites, see curves B and C in FIG. 1.
  • Another feature of the invention is the adjustment of the grain analysis in such a manner that, on the one hand, an optimum compaction is possible, and on the other hand, there is still room for further compaction in grain interstices when the annular furnace liner undergoes thermal expansion.
  • Examples of the grain composition of the invention are given in Table 1 at the end of this description, by way of example. Accordingly, 60 to 40% of the grain composition consists of grains of 5.0 to 0.6 mm., 30% of grains smaller than 0.06 mm., and the balance of 0.6 and 0.06 mm. grains.
  • energy is delivered through the inserted form which establishes the cavity in the refractory grain mixture, to a suflicient extent to produce an optimum density.
  • This furnace lining is not, of course, sufiiciently stable to withstand mechanical stresses, such as, for example, those produced by the vibrations of the electrical energy of the induction coil-
  • a phosphate binder is added to the self-supporting furnace liner after removal of the form.
  • FIG. 3 is a cross section of the crucible of an induction furnace which consists of an outer wall 1, an intermediate form 2 and the refractory liner 3. The latter is adjoined on the inside by'the form 4, which is removed after the compaction or densification in order then to permit the application of the phosphate binder to the surface of the refractory liner 3, which is preferably performed by spraying.
  • a special mineral-chemical binder is added to the portion of the liner adjacent the melt.
  • This is a phosphate binder, preferably a monoaluminum phosphate binder with variable phosphate members.
  • binders which may also contain chromium oxide additives, develop strengths between and 20 kg./ crn. even at room temperature when added in quantities of 6 to 8% to the dry granular mixture.
  • a liner in accordance with the invention it is desirable to prepare a liner in accordance with the invention in such a manner that the dry, refractory granular composition, mixed with the dry sintering agent, is compacted in the furnace to a total pore volume of 16 to 24%, using a removable, re-usable form. The form is then removed and the inner layer of the liner is impregnated with the binding agent.
  • the furnace can be started up in the customary manner using a burner system, a starting ingot and/or a batch of molten metal, because the liner creates conditions no difierent from those known in the past.
  • the cavity between furnace wall and form was filled up with dry tertiary quartzite having a grain size composition as described in Example 1 of Table 1 in mixture with dry boric acid (1% of the mass).
  • a vibrator driven by compressed air was attached to the form and put into operation for 6 minutes. Thereafter the form was re moved from the furnace.
  • On the interior surface of the liner monoaluminum phosphate was sprayed in a quantity of 1 litre per square meter of the surface. Thereafter, the lining was heated to 400 C. by induction heating. Finally the furnace was charged with material to be melted and heated to melting temperatures above 1500 C. During this heating the inner shell of the liner was sintered, whereas the outer zones of the liner remained unsintered.
  • Example 1 Example 2
  • Example 3 Grain size composition (mm.) (percent) (p ereent) (percent) Total 43. 45 54. 60 57. 15
  • heating step (e) is carried out at a temperature between 400 and 700 C.
  • binding agent is selected from the group consisting of sodium silicates, silicic acid esters, tar, dextrine solutions and sulphite waste liquor.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)
  • Compositions Of Oxide Ceramics (AREA)
US00194949A 1970-11-04 1971-11-02 Method of making liner in an induction melting furnace Expired - Lifetime US3836613A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2054136A DE2054136C2 (de) 1970-11-04 1970-11-04 Selbststehendes Futter in einem Induktionsschmelzofen und Verfahren zu seiner Herstellung

Publications (1)

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US3836613A true US3836613A (en) 1974-09-17

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US (1) US3836613A (enExample)
DE (1) DE2054136C2 (enExample)
FR (1) FR2112459B1 (enExample)
GB (1) GB1372534A (enExample)
IT (1) IT943640B (enExample)
SE (1) SE376651B (enExample)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218418A (en) * 1978-06-22 1980-08-19 Crystal Systems, Inc. Processes of casting an ingot and making a silica container
WO1982003451A1 (fr) * 1981-03-31 1982-10-14 Zhukov Leonid Fedorovich Procede de garnissage d'une installation metallurgique
US4818224A (en) * 1987-12-11 1989-04-04 Shell Oil Company Process
US5495495A (en) * 1995-05-25 1996-02-27 Saint-Gobain/Norton Industrial Ceramics Corporation Dense lining for coreless induction furnace
US10295260B2 (en) 2016-10-18 2019-05-21 Saint-Gobain Ceramics & Plastics, Inc. Ceramic liner and method of forming
CN114383390A (zh) * 2021-12-30 2022-04-22 潍坊信合节能科技有限公司 一种中频感应透热炉及中频感应透热炉炉衬烘干工艺
US20230349638A1 (en) * 2022-04-05 2023-11-02 Doggone Investment Co. LLC Apparatus and method for production of high purity copper-based alloys

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2612912C2 (de) * 1976-03-26 1984-09-06 Dörentruper Sand- und Thonwerke GmbH, 4926 Dörentrup Verfahren und Vorrichtung zur Fertigstellung eines Schmelzofens
BE837268A (fr) * 1975-12-31 1976-06-30 Materiaux refractaires ameliores destines a constituer le revetement interieur de fours a usage metallurgique et plus specialement des fours electriques a induction
DE3725173A1 (de) * 1987-07-29 1989-02-16 Fleischmann Adolf A Fa Heissreparaturverfahren an rinneninduktionsoefen fuer metallschmelzen
GB2393500B (en) * 2003-01-29 2004-09-08 Morgan Crucible Co Induction furnaces and components
CN102584187B (zh) * 2012-01-16 2013-10-16 芜湖市天地电子科技有限公司 一种高硼管及其制备方法

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4218418A (en) * 1978-06-22 1980-08-19 Crystal Systems, Inc. Processes of casting an ingot and making a silica container
WO1982003451A1 (fr) * 1981-03-31 1982-10-14 Zhukov Leonid Fedorovich Procede de garnissage d'une installation metallurgique
US4480820A (en) * 1981-03-31 1984-11-06 Institut Problem Litia Akademii Nauk Ukrainskoi Ssr Method of lining metallurgical assembly
US4818224A (en) * 1987-12-11 1989-04-04 Shell Oil Company Process
US5495495A (en) * 1995-05-25 1996-02-27 Saint-Gobain/Norton Industrial Ceramics Corporation Dense lining for coreless induction furnace
DE19621423A1 (de) * 1995-05-25 1996-12-12 Saint Gobain Norton Ind Cerami Kernloser Induktionsofen und Verfahren zu dessen Herstellung
US10295260B2 (en) 2016-10-18 2019-05-21 Saint-Gobain Ceramics & Plastics, Inc. Ceramic liner and method of forming
US11181321B2 (en) 2016-10-18 2021-11-23 Saint-Gobain Ceramics & Plastics, Inc. Ceramic liner and method of forming
CN114383390A (zh) * 2021-12-30 2022-04-22 潍坊信合节能科技有限公司 一种中频感应透热炉及中频感应透热炉炉衬烘干工艺
US20230349638A1 (en) * 2022-04-05 2023-11-02 Doggone Investment Co. LLC Apparatus and method for production of high purity copper-based alloys
US11993828B2 (en) * 2022-04-05 2024-05-28 Doggone Investment Co. LLC Apparatus and method for production of high purity copper-based alloys
US12234531B2 (en) 2022-04-05 2025-02-25 Doggone Investment Co. LLC Apparatus and method for production of high purity copper-based alloys
US12371760B2 (en) 2022-04-05 2025-07-29 Doggone Investment Co. LLC Apparatus and method for production of high purity copper-based alloys

Also Published As

Publication number Publication date
FR2112459A1 (enExample) 1972-06-16
GB1372534A (en) 1974-10-30
DE2054136A1 (enExample) 1972-05-25
DE2054136C2 (de) 1975-04-10
DE2054136B2 (de) 1972-05-25
IT943640B (it) 1973-04-10
FR2112459B1 (enExample) 1977-01-28
SE376651B (enExample) 1975-06-02

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