EP0108178B1 - Removal of alkali metals and alkaline earth metals from molten aluminium - Google Patents

Removal of alkali metals and alkaline earth metals from molten aluminium Download PDF

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Publication number
EP0108178B1
EP0108178B1 EP82305965A EP82305965A EP0108178B1 EP 0108178 B1 EP0108178 B1 EP 0108178B1 EP 82305965 A EP82305965 A EP 82305965A EP 82305965 A EP82305965 A EP 82305965A EP 0108178 B1 EP0108178 B1 EP 0108178B1
Authority
EP
European Patent Office
Prior art keywords
impeller
axis
vessel
rotation
molten
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
Application number
EP82305965A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0108178A1 (en
Inventor
Ghyslain Dubé
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.)
Rio Tinto Alcan International Ltd
Original Assignee
Alcan International Ltd Canada
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Alcan International Ltd Canada filed Critical Alcan International Ltd Canada
Priority to DE8282305965T priority Critical patent/DE3276823D1/de
Priority to EP82305965A priority patent/EP0108178B1/en
Priority to CA000440674A priority patent/CA1215237A/en
Priority to NO834081A priority patent/NO162028C/no
Priority to AU21077/83A priority patent/AU562966B2/en
Priority to ES527104A priority patent/ES8504267A1/es
Priority to JP58210695A priority patent/JPS59100231A/ja
Publication of EP0108178A1 publication Critical patent/EP0108178A1/en
Application granted granted Critical
Publication of EP0108178B1 publication Critical patent/EP0108178B1/en
Expired legal-status Critical Current

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Classifications

    • 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
    • F27D27/00—Stirring devices for molten material
    • 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
    • C22B21/00—Obtaining aluminium
    • C22B21/06—Obtaining aluminium refining
    • C22B21/062—Obtaining aluminium refining using salt or fluxing agents

Definitions

  • This invention relates to the removal of contaminant quantities of alkali metals and alkaline earth metals from molten aluminium by reaction with aluminium fluoride.
  • U.S. 3,620,716 discloses a method of removing magnesium from molten aluminium by fluxing with a cover flux containing AIF 3 . According to this document, the flux is stirred into the melt and the melt is then left for at least a few hours to allow reaction between the flux and the contaminant.
  • the particulate aluminium fluoride-yielding material is supplied to enter the vortex and become entrained in the molten aluminium and the stirring of the molten aluminium is continued until the alkali metal and alkaline earth metal content is reduced to a desired low level.
  • the vortex was preferably generated by means of a multi-blade impeller having blades inclined to its axis of rotation and in the already described process this was preferably arranged somewhat eccentrically in relation to the axis of a cylindrical vessel having a vertically arranged axis. It was found that optimum results were achieved by careful dimensioning of the impeller in relation to the dimension of the treatment vessel and also to the depth of molten metal to be contained in the vessel, generally a vessel for transferring a body of molten metal from a reduction cell to a casting station.
  • d is the overall diameter of the bladed portion of the impeller
  • h is the height of the impeller blades
  • y is the vertical distance from the bottom of the crucible interior to the midpoint of the impeller blades
  • H is the vertical distance from the bottom of the crucible interior to the quiescent level of molten metal in the crucible
  • D is the internal diameter of the crucible.
  • the impeller was preferably eccentrically located at a distance of 0.1­0.25D and more preferably at a distance of 0.25-0.7 d in relation to the axis of the vessel.
  • Solid particulate material can be entrained in and reacted with alkali metal contaminants in molten aluminium by generation of a vortex in such non-cylindrical masses with similar efficiency to that achieved when the metal is contained in an upright cylindrical crucible, thus permitting the process to be employed in all forms of transfer crucible, particularly crucibles having an essentially continuous, rounded sidewall surface free from recesses or abrupt angles, which would result in locally stagnant zones within the upwardly spiralling molten metal flow in the peripheral region of the vessel.
  • the stirrer In performing the process of the present invention in the crucibles illustrated in Figures 1-4 the stirrer is constructed and arranged to operate in the same way as in our co-pending European Patent Application No. 82.302448.4.
  • the stirrer is supported by a lid (not shown) and a duct is arranged on the lid for the supply of a particulate aluminium fluoride-yielding material (which expression embraces compounds such as KAIF 4 on to the surface of the molten metal in the vessel).
  • alkali and alkaline earth metals react preferentially with AIF 3 (compared to aluminium) to form mixed alkali cryolithionite compounds, e.g. Na 5 Al 3 F 14 , Na 3 LiAlF 3 , and Li 3 Na 3 Al 2 F 12 .
  • the vessel may be shaped as shown in Figures 2 and 3, and may be axially tilted with even an axially tilted stirrer (Fig. 4), although a vertical axis of stirrer rotation is preferred because of the effect of gravity on vortex generation.
  • the diameter D is the minimum internal diametrical dimension (i.e. measured through the geometric axis of the vessel) of the metal-containing vessel in the plane of impeller rotation.
  • Blade diameter d and eccentricity x are also measured in the plane of impeller rotation, while blade height h, distance y, and distance H are all measured along the axis of impeller rotation, and pitch angle 8 is measured with reference to the axis of impeller rotation.
  • Figure 1 represents the surface, having perimeter 10', of a body of molten metal contained in a cylindrical crucible tilted with respect to the impeller axis.
  • G is the geometric axis of the elliptical surface of the molten metal
  • D is the short diameter of the ellipse
  • L is the long diameter of the ellipse.
  • the eccentricity x is clearly greater than D/4, but the axis of impeller rotation is spaced from the crucible wall by a distance C greater than D/4.
  • the cross-sectional configuration of the crucible 10" in the plane of impeller rotation is bathtub-shaped, having semicircular ends and straight parallel sides spaced apart by a distance equal to the diameter of the semi-circular ends.
  • the minimum diameter D through the geometric axis G in this plane is the distance between the parallel sides (viz. the diameter of the semi-circular ends), while the long diameter L is equal to A+D, where A is the spacing between the centres of the semi-circles.
  • the crucible 10"' shown in elevational cross-section in Figures 3 and 4 has a geometric axis G tilted with respect to the vertical.
  • the axis of rotation of the impeller 14 is vertical; hence y is a vertical distance (from the midpoint of the impeller blades to the point on the crucible floor vertically beneath that midpoint) and eccentricity x is measured in the horizontal plane P of impeller rotation, which is at an oblique angle to G.
  • a mass of molten metal, held in a tilted cylindrical crucible assumes an essentially non-cylindrical shape, having an elliptical surface.
  • the top surface of the body of metal in the tilted, tapering crucible of Figures 3 and 4 is also ellipsoidal in shape.
  • the treatment material may comprise aluminium fluoride, possibly containing up to 50% inert material, such as aluminium oxide.
  • aluminium fluoride may be added in chemically-bound form, such as a fluoaluminate of sodium or potassium. Conveniently it may be added as NaF/AIF 3 having a low NaF/AIF 3 ratio by weight, for example 0.6-0.7/1.
  • Aluminium fluoride may also be added admixed with other alkali metal fluorides or chlorides or alkaline earth metal fluorides or chlorides.
  • any active fluorine-containing compound could be added, i.e. any such compound which on addition to molten aluminium will liberate a fluoride which is reactive towards alkali or alkaline earth metal contaminants and does not introduce other undesirable contaminants into the molten aluminium.
  • KBF 4 and K 2 TiF 6 are examples of such compounds.
  • aluminium fluoride or “aluminium fluoride-yielding material”.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP82305965A 1982-11-09 1982-11-09 Removal of alkali metals and alkaline earth metals from molten aluminium Expired EP0108178B1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
DE8282305965T DE3276823D1 (en) 1982-11-09 1982-11-09 Removal of alkali metals and alkaline earth metals from molten aluminium
EP82305965A EP0108178B1 (en) 1982-11-09 1982-11-09 Removal of alkali metals and alkaline earth metals from molten aluminium
CA000440674A CA1215237A (en) 1982-11-09 1983-11-08 Removal of alkali metals and alkaline earth metals from molten aluminium
NO834081A NO162028C (no) 1982-11-09 1983-11-08 Fremgangsmaate ved fjerning av alkali- og jordalkalimetaller fra smeltet aluminium, samt apparat for utfoerelse av fremgangsmaaten.
AU21077/83A AU562966B2 (en) 1982-11-09 1983-11-08 Removal of alkali metals and alkaline earth metals from molten aluminium
ES527104A ES8504267A1 (es) 1982-11-09 1983-11-08 Un metodo de separar metales alcalinos y metales alcalino-terreos contaminantes de una masa no cilindrica de aluminio fundido contenida dentro de un recipiente
JP58210695A JPS59100231A (ja) 1982-11-09 1983-11-09 アルミニウムの精製方法およびその装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP82305965A EP0108178B1 (en) 1982-11-09 1982-11-09 Removal of alkali metals and alkaline earth metals from molten aluminium

Publications (2)

Publication Number Publication Date
EP0108178A1 EP0108178A1 (en) 1984-05-16
EP0108178B1 true EP0108178B1 (en) 1987-07-22

Family

ID=8189827

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82305965A Expired EP0108178B1 (en) 1982-11-09 1982-11-09 Removal of alkali metals and alkaline earth metals from molten aluminium

Country Status (7)

Country Link
EP (1) EP0108178B1 (no)
JP (1) JPS59100231A (no)
AU (1) AU562966B2 (no)
CA (1) CA1215237A (no)
DE (1) DE3276823D1 (no)
ES (1) ES8504267A1 (no)
NO (1) NO162028C (no)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3367112D1 (en) * 1982-11-16 1986-11-27 Alcan Int Ltd Removal of impurities from molten aluminium
GB8428251D0 (en) * 1984-11-08 1984-12-19 Alcan Int Ltd Treating aluminium
US5080715A (en) * 1990-11-05 1992-01-14 Alcan International Limited Recovering clean metal and particulates from metal matrix composites

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3620716A (en) * 1969-05-27 1971-11-16 Aluminum Co Of America Magnesium removal from aluminum alloy scrap

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3459536A (en) * 1964-11-06 1969-08-05 Interlake Steel Corp Method for mixing molten metal
GB1367069A (en) * 1970-10-22 1974-09-18 British Aluminium Co Ltd Removal of non-metallic constituents from liquid metal
US4060409A (en) * 1976-02-23 1977-11-29 Kennecott Copper Corporation Mechanically stirred furnace for pyrometallurgical operations and processes
US4058394A (en) * 1976-02-23 1977-11-15 Kennecott Copper Corporation Pyrometallurgical system for solid-liquid contacting
CA1188107A (en) * 1981-05-19 1985-06-04 Ghyslain Dube Removal of alkali metals and alkaline earth metals from molten aluminium
JPS6017009A (ja) * 1983-07-11 1985-01-28 Mitsubishi Metal Corp 製錬炉の羽口部構造

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3620716A (en) * 1969-05-27 1971-11-16 Aluminum Co Of America Magnesium removal from aluminum alloy scrap

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
The Shorter Oxford English Dictionary (1973), page 480 *

Also Published As

Publication number Publication date
ES527104A0 (es) 1985-04-01
DE3276823D1 (en) 1987-08-27
AU562966B2 (en) 1987-06-25
EP0108178A1 (en) 1984-05-16
NO162028C (no) 1989-10-25
NO834081L (no) 1984-05-10
JPS59100231A (ja) 1984-06-09
NO162028B (no) 1989-07-17
ES8504267A1 (es) 1985-04-01
CA1215237A (en) 1986-12-16
AU2107783A (en) 1984-05-17

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