EP0248396B1 - Verfahren zum Herstellen von Hüllmaterial durch kombiniertes Umschmelzen mit Elektronenstrahlen und Vakuum-Lichtbogen - Google Patents

Verfahren zum Herstellen von Hüllmaterial durch kombiniertes Umschmelzen mit Elektronenstrahlen und Vakuum-Lichtbogen Download PDF

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Publication number
EP0248396B1
EP0248396B1 EP87107945A EP87107945A EP0248396B1 EP 0248396 B1 EP0248396 B1 EP 0248396B1 EP 87107945 A EP87107945 A EP 87107945A EP 87107945 A EP87107945 A EP 87107945A EP 0248396 B1 EP0248396 B1 EP 0248396B1
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EP
European Patent Office
Prior art keywords
ingot
melting
zirconium
sponge
process according
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.)
Expired - Lifetime
Application number
EP87107945A
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English (en)
French (fr)
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EP0248396A2 (de
EP0248396A3 (en
Inventor
Samuel Austin Worcester
Charles Robert Woods
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.)
CBS Corp
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Westinghouse Electric Corp
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Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Publication of EP0248396A2 publication Critical patent/EP0248396A2/de
Publication of EP0248396A3 publication Critical patent/EP0248396A3/en
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Classifications

    • 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
    • C22B9/20—Arc remelting
    • 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
    • C22B34/00—Obtaining refractory metals
    • C22B34/10—Obtaining titanium, zirconium or hafnium
    • C22B34/14—Obtaining zirconium or hafnium
    • 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
    • C22B9/22—Remelting metals with heating by wave energy or particle radiation
    • C22B9/228—Remelting metals with heating by wave energy or particle radiation by particle radiation, e.g. electron beams

Definitions

  • This invention relates to the production of purified zirconium.
  • the conventional process for making zirconium metal utilizes a fluidized bed process in which the ore is subjected to a chlorination step which produces a relatively impure, hafnium-containing zirconium tetrachloride and by-product silicon tetrachloride (which by-product is relatively easily separated).
  • the hafnium and zirconium containing material is then subjected to a number of purifying operations and also a complex hafnium separation operation. These operations result in purified oxides of zirconium and hafnium, which, of course, are maintained separate.
  • the purified oxides are separately chlorinated.
  • Zirconium and hafnium are commonly reduced from the chloride by means of a reducing metal, typically magnesium.
  • U.S. Patent Specification No. 3,966,460 describes a process of introducing zirconium tetrachloride vapor onto molten magnesium, with the zirconium being reduced and traveling down through the magnesium layer to the bottom of the reactor and forming a metallic sponge.
  • the metallic sponge (containing remaining chloride and some remaining excess reducing metal) is then placed in a distillation vessel for removal of the remaining salt and reducing metal by high temperature vacuum distillation.
  • the sponge material is generally crushed, screened and pressed into electrodes for vacuum arc melting. Particularly, the material is multiple (typical double or triple) vacuum arc melted to provide ingots which are then further fabricated into various shapes.
  • Most of the zirconium currently is used to produce Zircaloy.
  • Zircaloy tubes as cladding material to contain the uranium dioxide fuel.
  • a Zircaloy ingot is processed into a so-called "trex" and pilgering operations are used to reduce the trex inside diameter and wall thickness to size.
  • Ultra-pure zirconium has been proposed for a liner for the inside surface of Zircaloy tubing which is used as a cladding for nuclear fuel and is described in, for example, U.S. Patent Specification No. 4,372,817 (Armijo et al.).
  • a similar use of moderate purity material is proposed in U.S. Patent Specification No. 4,200,492 (Armijo et al.).
  • the ultra-pure zirconium material described has been purified by iodide cells to produce so called "crystal bar” material.
  • This rather expensive crystal bar processing is performed after reduction and is described, for example, in U.S. Patent Specification No. 4,368,072 (Siddal).
  • EB (electron beam) melting of materials has been discussed in a number of U.S. patent specifications. EB melting has been used to consolidate crushed particles or chips in so called hearth furnaces and to separate impurities by either overflowing floating inclusions (U.S. Patent Specification No. 4,190,404 (Drs et al.)) or to produce an electrode for arc melting (U.S. Patent Specification No. 4,108,644 (Walberg et al.)).
  • U.S. patent specifications have described the EB melting of powders or granules, often producing an ingot in a chilled mold. These powder melting EB patents include U.S. Patent Specification No.
  • Patent Specification No. 3,091,525 (D'A. Hunt) describes adding a small amount of zirconium, for example, to hafnium, for example and melting in an EB furnace to deoxidize the hafnium.
  • Japanese application 1979-144789 Kawakita published as patent publication 1981-67788 describes the use of a very small ingot with a high power density and ultra slow melting to produce a deep molten pool to produce a high purity ingot directly usable for lining of Zircaloy tubing for nuclear reactor applications.
  • Such laboratory sized apparatus with its high powered consumption and very low throughput is, of course, not practical for commercial production.
  • a process for producing zirconium in purified form for use in lining the interior of zirconium alloy fuel element cladding comprises reducing zirconium tetrachloride to produce a sponge of metallic zirconium which is distilled to generally remove residual magnesium and magnesium chloride, and melting the distilled sponge to produce an ingot of non-crystal bar material, by forming said distilled sponge into a consumable electrode by pressing crushed virgin sponge into the form of an electrode and then welding an end fitting to the electrode; melting said consumable electrode in a multiple swept beam electron furnace with a feed rate of from 2,5 cm to 51 cm (1 to 20 inches) per hour to form an intermediate ingot, the intermediate ingot having a diameter of greater than 12,7 cm (5 inches); and vacuum arc melting said intermediate ingot to produce a homogeneous final ingot having 50 - 300 ppm iron, 250 - 450 ppm oxygen and 500 - 1000 ppm of total impurities.
  • this process provides material much purer than the so called sponge material and almost as pure as the crystal bar material, at a fraction of the cost of crystal bar material.
  • Generally purified zirconium produced according to the present invention has oxygen in the 250-450 ppm range (and preferably less than about 350) and iron in the 50-300 ppm range.
  • Total impurities are generally in the 500-1000 ppm range (total impurities for these purposes generally comprise the elements listed in the afore-mentioned U.S. Patent Specification No. 4,200,492).
  • the energy input via the electron beams is maintained to a moderate level such that the molten pool on the upper portion of the intermediate ingot has a depth of less than about one fourth of the ingot diameter, thus lowering power costs.
  • an argon sweep is provided in the electron beam furnace during melting. Multiple passes may be made both through the EB furnace and the vacuum arc furnace.
  • the distilled zirconium sponge is formed into a consumable electrode for use in a production EB furnace.
  • a production furnace is generally shown in the afore-mentioned U.S. Patent Specification No. 3,219,435, but with the multiple beams being constantly swept across the surface of the molten pool (as defined herein, a production EB furnace has an output "intermediate" ingot having a diameter greater than five inches, and generally greater than six inches.
  • this consumable electrode for EB melting is formed by pressing crushed virgin sponge (not recycle scrap). The compact and an appropriate end fitting are welded to form the consumable electrode.
  • the consumable EB electrode is melted in a production electron beam furnace with a feed rate of from 2.54 - 50.8 cms per hour (1 to 20 inches per hour). It has been found that small amounts of residual magnesium chloride remain in the electrode and absorb some moisture. Melting at faster than 50.8 cms (20 inches) per hour results in this moisture reacting to oxidized zirconium and thus causing an unacceptably high oxygen level in the product. Conversely too slow a melting rate, while possibly removing some oxygen from the molten pool (as described in the afore-mentioned Japanese patent publication 1981-67788) is uneconomical.
  • an argon sweep is provided in the electron beam furnace during melting. It is felt that this helps remove moisture which has been vaporized off the electron from the furnace, minimizing contamination of the output intermediate ingot.
  • the argon sweep is at a flow of 10,000-1,000,000 liters per second, with the liters measured at a pressure of 1,33 ⁇ 10 ⁇ 5 Pa (10 ⁇ 5 Torr) (rather than at standard conditions).
  • the argon sweep can be established, for example, with pumps capable of handling 60,000 liters per second and with a pressure of 1,33 ⁇ 10 ⁇ 5 Pa (10 ⁇ 5 Torr) measured with no argon flow, by controlling argon introduction to a rate to raise the pressure to approximately 1,33 ⁇ 10 ⁇ 4 Pa (10 ⁇ 4 Torr).
  • the sponge used to form the consumable electrode is generally virgin material (as opposed to recycled scrap or turnings) and preferably is selected high quality material and generally selected for low oxygen content.
  • the material is arc melted (and preferably double arc melted or even triple arc melted) to homogenize the impurity distribution. It has been found that in production EB furnaces, with their relatively shallow molten pool (the molten pool being shallow both in comparison to arc melting, where the molten pool is typically about twice the ingot diameter and in comparison to non-multiple swept beam, laboratory type furnaces where the fixed single beam covers essentially the entire surface of the molten pool and produces molten pools of about one diameter in depth) do not produce a homogeneous product.
  • the zirconium material beneath the molten pool is, of course, solid, and can be slowly withdrawn as material from the electrode drips into the pool, as it is known in the prior art.
  • the shallow molten pool results in a non-homogeneous product, and only by following such melting with vacuum arc melting can a homogeneous product be obtained.
  • non-swept beam EB furnaces having very high power costs for very low throughput, are impractical for commercial applications.
  • This invention lowers oxygen by removing at least some of the moisture prior to melting while the laboratory type of EB furnace is generally removing oxygen from the molten pool.

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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)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Claims (6)

  1. Ein Verfahren zur Erzeugung von Zirconium in gereinigter Form zur Verwendung in der Auskleidung des Inneren einer Zirconiumlegierungsbrennstoffelementummantelung, die das Reduzieren von Zirconiumtetrachlorid zur Erzeugung eines Schwammes von metallischen Zirconium umfaßt, welches destilliert wird, um allgemein Restmagnesium und Magnesiumchlorid zu entfernen, und Schmelzen des destillierten Schwammes zur Erzeugung eines Barrens aus nicht kristallisiertem Barrenmaterial,
    durch
    a) Formen des destillierten Schwammes zu einer verbrauchbaren Elektrode durch Pressen von zerdrücktem jungfräulichem Schwamm zu der Form einer Elektrode und dann Schweißen eines Endanschlusses an die Elektrode;
    b) Schmelzen der verbrauchbaren Elektrode in einem Vielfachverschwenkungsstrahlelektronenofen mit einer Zufuhrrate von 2,54 cm (1 Zoll) bis 50,8 cm (20 Zoll) pro Stunde, um einen Zwischenbarren zu erzeugen, wobei der Zwischenbarren einen Durchmesser aufweist, der größer ist als 12,7 cm (5 Zoll);
    c) und Vakuumlichtbogenschmelzen des Zwischenbarrens; um dadurch einen homogenen endgültigen Barren zu erzeugen, der 50 bis 300 ppm Eisen, 250 bis 450 ppm Sauerstoff und 500 bis 1000 ppm gesamte Unreinheiten besitzt.
  2. Ein Verfahren nach Anspruch 1, gekennzeichnet dadurch, daß der Zwischenbarren auf seinem oberen Teil einen geschmolzenen Teich mit einer Tiefe von weniger als einem Viertel des Barrendurchmessers aufweist.
  3. Ein Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß eine Argonspülung in dem Elektronenstrahlofen während des Schmelzens vorgesehen ist.
  4. Ein Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß die Argonspülung eine Strömung von 10.000 bis 1.000.000 Liter pro Sekunde ist, gemessen bei einem Druck von 1,33 X 10⁻⁵ Pa (10⁻⁵ Torr).
  5. Ein Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß Vielfachdurchläufe durch den Elektronenstrahlofen gemacht werden.
  6. Ein Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß Vielfachdurchläufe durch den Vakuumlichtbogenofen gemacht werden.
EP87107945A 1986-06-05 1987-06-02 Verfahren zum Herstellen von Hüllmaterial durch kombiniertes Umschmelzen mit Elektronenstrahlen und Vakuum-Lichtbogen Expired - Lifetime EP0248396B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US87118386A 1986-06-05 1986-06-05
US871183 1986-06-05

Publications (3)

Publication Number Publication Date
EP0248396A2 EP0248396A2 (de) 1987-12-09
EP0248396A3 EP0248396A3 (en) 1990-04-25
EP0248396B1 true EP0248396B1 (de) 1993-04-28

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EP87107945A Expired - Lifetime EP0248396B1 (de) 1986-06-05 1987-06-02 Verfahren zum Herstellen von Hüllmaterial durch kombiniertes Umschmelzen mit Elektronenstrahlen und Vakuum-Lichtbogen

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EP (1) EP0248396B1 (de)
KR (1) KR880000607A (de)
DE (1) DE3785605T2 (de)
ES (1) ES2040712T3 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4849016A (en) * 1987-12-18 1989-07-18 Westinghouse Electric Corp. Combined ultra slow electron beam and vacuum arc melting for barrier tube shell material
US5062887A (en) * 1991-02-08 1991-11-05 Westinghouse Electric Corp. Process for chloride removal from sponge metal
JP4058777B2 (ja) * 1997-07-31 2008-03-12 日鉱金属株式会社 薄膜形成用高純度ルテニウム焼結体スパッタリングターゲット及び同ターゲットをスパッタリングすることによって形成される薄膜

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1110877B (de) * 1959-04-24 1961-07-13 Heraeus Gmbh W C Verfahren zum Erschmelzen von Metallbloecken mittels Elektronenstrahlen
US3091525A (en) * 1959-05-01 1963-05-28 Stauffer Chemical Co Deoxidation of refractory metal
DE1121281B (de) * 1959-11-07 1962-01-04 Heraeus Gmbh W C Schmelzanlage zum Schmelzen von Metallen unter reduziertem Druck
FR1331472A (fr) * 1962-05-22 1963-07-05 Applic Electro Thermiques Et C Procédé pour la purification de métaux à température de fusion élevée, notamment du zirconium, et dispositif pour la mise en oeuvre de ce procédé
US4108644A (en) * 1976-11-11 1978-08-22 Viking Metallurgical Corp. Manufacture of reactive metals and alloys
JPS5667788A (en) * 1979-11-08 1981-06-08 Tokyo Shibaura Electric Co Manufacture of cladding tube for nuclear fuel element
JPS60124452A (ja) * 1983-12-07 1985-07-03 Hitachi Ltd 高純度金属スリ−ブの製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Winkler et al., VACUUM METALLURGY, 1971, Elsevier, Amsterdam-London-New York; pp. 270, 271, 618, 619, 625, 626# *

Also Published As

Publication number Publication date
KR880000607A (ko) 1988-03-28
DE3785605D1 (de) 1993-06-03
EP0248396A2 (de) 1987-12-09
DE3785605T2 (de) 1993-08-12
EP0248396A3 (en) 1990-04-25
ES2040712T3 (es) 1993-11-01

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