EP0065534A1 - Cathode pour cellule d'electrolyte fondu pour la preparation d'aluminium. - Google Patents

Cathode pour cellule d'electrolyte fondu pour la preparation d'aluminium.

Info

Publication number
EP0065534A1
EP0065534A1 EP81903120A EP81903120A EP0065534A1 EP 0065534 A1 EP0065534 A1 EP 0065534A1 EP 81903120 A EP81903120 A EP 81903120A EP 81903120 A EP81903120 A EP 81903120A EP 0065534 A1 EP0065534 A1 EP 0065534A1
Authority
EP
European Patent Office
Prior art keywords
aluminum
elements
cathode according
aluminide
solid cathode
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.)
Granted
Application number
EP81903120A
Other languages
German (de)
English (en)
Other versions
EP0065534B1 (fr
Inventor
Tibor Kugler
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 Switzerland AG
Original Assignee
Alusuisse Holdings AG
Schweizerische Aluminium AG
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 Alusuisse Holdings AG, Schweizerische Aluminium AG filed Critical Alusuisse Holdings AG
Priority to AT81903120T priority Critical patent/ATE9234T1/de
Publication of EP0065534A1 publication Critical patent/EP0065534A1/fr
Application granted granted Critical
Publication of EP0065534B1 publication Critical patent/EP0065534B1/fr
Expired legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/08—Cell construction, e.g. bottoms, walls, cathodes

Definitions

  • the invention relates to an exchangeable wettable solid-state cathode for a melt flow electrolytic cell for the production of aluminum.
  • the electrolysis generally takes place in a temperature range of about 940-970 ° C.
  • the electrolyte becomes poor in aluminum oxide.
  • aluminum oxide in the electrolyte there is an anode effect, which results in a voltage increase from, for example, 4-4.5 V to 30 V and above.
  • the crust formed from solidified electrolyte material must be hammered in and the aluminum oxide concentration increased by adding new aluminum oxide (alumina).
  • cathodes made of titanium ciboride, titanium carbide, pyrolytic graphite, boron carbide and other substances are used beaten, mixtures of these substances, which are known, for example, to be sintered together, are also used.
  • cathodes that can be wetted with aluminum offer decisive advantages.
  • the deposited metal already flows when a very thin layer is formed on the cathode surface facing the anode surface. It is therefore possible to remove the deposited liquid aluminum from the gap between the anode and cathode and to feed it to a sump located outside the gap. Thanks to the thin aluminum layer on the solid cathode, the non-uniformities known from conventional electrolysis with respect to the thickness of the aluminum layer - under the influence of electromagnetic and convectional forces - do not form. Therefore, the interpolar distance can be reduced without losing current density, i.e. a significantly lower energy consumption per unit of reduced metal is achieved.
  • DE-OS 28 38 965 proposes solid-state cathodes made of individually replaceable elements, each with at least one power supply. Since wettable cathode materials based on hard metals, such as borides, nitrides and carbides of titanium, chromium and hafnium, are relatively expensive, the replaceable solid-state cathodes are partially substituted.
  • the interchangeable elements are made of two materials made from two materials, made of two materials that are mechanically rigidly connected to one another and resistant to thermal shocks - an upper part protruding from the molten electrolyte into the separated aluminum and a lower part arranged exclusively in liquid aluminum.
  • the upper part at least in the area of the surface, is unchanged from aluminum wettable Material, while the lower part or its coating consists of an insulator material resistant to the liquid aluminum.
  • the inventor has therefore set himself the task of creating exchangeable solid-state cathodes with simple manufacturing technology, which have a lower brittleness and yet meet all the economic and technical requirements of modern aluminum electrolysis.
  • the cathode consists of an aluminide of at least one metal from the group formed from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten, without binding phase from metallic aluminum.
  • the non-aluminum components of the aluminide thus belong to Group IV A, V A and / or VI A of the Periodic Table of the Elements.
  • the aluminides are present as individual binary compounds or as ternary, quaternary or quinary alloys. Their chemical and thermal resistance allows them to be used in both fast-flowing electrolytes and molten aluminum, although they are only sparingly soluble in the latter. However, this solubility drops sharply with falling temperature.
  • the solubility of a metallic non-aluminum component of the aluminide in the liquid aluminum is of the order of magnitude of approximately 1%.
  • the cathode selenium elements are thus removed until the liquid aluminum deposited is saturated with one or more of the metallic non-aluminum components.
  • the cathode elements made of an aluminide can take any known form, they can be formed from sub-elements combined in holders, in particular in the form of vertically arranged plates or rods. Because of the alloying of the aluminide cathode, however, elements firmly connected to the carbon base cannot be used; these must be interchangeable for economic and technical reasons. Since aluminide cathodes can not only be sintered, but can also be cast, the actual cathode elements and the holders can also be of a more complicated shape and / or can be formed in one piece. According to a further embodiment, aluminide cathode elements are arranged in refractory holders made of insulator material and resistant to molten aluminum.
  • aluminide balls and / or granules are also possible to pour into the electrolysis cells and distribute them evenly from the bath flow. If necessary, balls or granules that come into contact exclusively with the liquid metal can also consist of a corresponding insulator material.
  • the cathode elements For all geometrical shapes of the cathode elements, it is essential that the aluminide contains no metallic aluminum binding phase. This would melt at the working temperature of the electrolytic cell, which is why the cathode elements would be destroyed within a short time.
  • the metals titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and / or tungsten can be alloyed with de.n aluminides in a stoichiometric ratio, because their melting point is always above the electrolysis temperature of aluminum.
  • These metals are also known to be used as structural parts in the aluminide, for example as a honeycomb structure which is encased or sintered by the aluminide.
  • Aluminides are recovered from the deposited metal and can be used again to manufacture cathode elements. This creates a material cycle with relatively low losses.
  • titanium aluminides are preferably used as exchangeable, wettable solid-state cathodes.
  • titanium alloys with a few percent aluminum or aluminum alloys with a few percent titanium are normally used in the art.
  • the ⁇ -phase in relation to the alloy composition between TiAl and TiAl 3 has proven to be a very good cathode material.
  • Aluminum is characterized by TiAl 3 needles embedded in a matrix of TiAl.
  • An alloy richer in aluminum would not only, as mentioned, have an effect on the stability of the solid-state cathodes, but would also negatively affect the working conditions of the electrolytic cell.
  • phase diagrams for Ti-Al alloys in the relevant specialist literature show that the melting points of the ⁇ phase are between 1340 and 1460 ° C. These relatively low melting points allow the moldings to be produced from the aluminides both by melt metallurgy and by powder metallurgy.
  • the solubility of titanium in liquid aluminum is around 1.2%.
  • the aluminum deposited on the cathode elements will therefore alloy the titanium aluminide elements until its titanium content is enriched to 1.2%. This dissolves approximately 30 kg of the solid cathode material per ton of electrodeposited aluminum. 3 With a TiAl 3 cathode, this means a consumption of 11.15 kg titanium per ton of aluminum produced. If the cathode plates are inserted parallel to the underside of the carbon anodes, in practice the titanium aluminide is stripped down to around 50% of the original thickness.
  • cathode elements When changing the anode, 60 kg of cathode elements are brought into the electrolytic cell, which expediently form a unit that corresponds dimensionally to the working surface of the anode. Before inserting the new cathode elements, the residues, in the present case 30 kg, of the cathode residues must be removed from the electrolytic cell.
  • the aluminum obtained by electrolysis which contains the usual impurities in addition to 1.2% titanium, is placed in a holding furnace, for which the usual facilities are used. In this furnace, the temperature of the liquid metal is slowly lowered to approximately 700 ° C.
  • the TiAl 3 that crystallizes out when the temperature drops has a density of 3.31 g / cm 3 and therefore sinks to the bottom in the lighter liquid aluminum.
  • known means such as tilting the furnace, suctioning off the liquid metal or centrifuging, the aluminum containing 0.2% titanium is separated from the precipitate.
  • the aluminum can be tarem boron, a boron-aluminum alloy or a boron compound, such as potassium borofluoride, can be treated, the titanium content of the deposited aluminum being able to be reduced to 0.01% by weight by precipitation of the titanium as titanium diboride.
  • the TiAl 3 precipitate formed on cooling the aluminum to 700 ° C. still contains small amounts of metallic aluminum, which are removed by a suitable treatment, for example an acid wash. If a titanium-rich alloy than TiAl 3 is desired, the phase that can be used for aluminide cathodes extends to TiAl, aluminum can be removed by chlorination.
  • the titanium aluminide obtained is transferred to the same system for the production of cathodes as the cathode residues discussed above. Examples of such systems are facilities for molding or di powder metallurgical shaping, which allow the production of the desired cathode shapes.
  • the small but unavoidable titanium losses can be compensated for by adding titanium dioxide in the electrolyte, to the alumina or to the alkalis of the alumina factory.
  • cathode elements can be made from other aluminides and used in aluminum electrolysis:
  • FIG. 1 and 2 show schematic vertical sections of aluminide cathodes connected to carrier plates.
  • FIG. 1 shows an essentially rectangular aluminide cathode plate 10 with a cover surface 12 running parallel to the underside of the anode.
  • the formation of a window 14 improves the flow conditions in the electrolyte.
  • the plate 10 On the underside, the plate 10 has a dovetail 16, which can be inserted into a corresponding recess in the carrier plate 18 made of insulating material.
  • This support plate 18 always remains in the area of the liquid metal in the working electrolysis cell.
  • the support structure for carrier plates is designed so that the plates cannot be moved laterally.
  • FIG. 2 Another variant of aluminide cathode plates 20 is shown in FIG. 2. Both the formation of a window 22 and the bevelled underside are intended on the one hand to save wettable material and on the other hand to optimize the flow conditions in the bath.
  • the plate 20 is fastened in a carrier or support plate 26 by means of an extension 24 directed downwards in the center.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

Une cathode solide interchangeable et mouillable pour l'electrolyse d'electrolyte fondu est constituee d'au moins un compose intermetallique d'aluminium du groupe IV A, V A ou VI A du systeme periodique des elements. Le compose d'aluminium et de titane en phase (Alpha) s'est montre particulierement avantageux. La forme d'execution representee a la figure 1 consiste en deux parties assemblees (10 et 18). La partie (10) dans la partie superieure est constituee en aluminate alors que la partie inferieure (18) et en un materiau isolant.
EP81903120A 1980-11-26 1981-11-16 Cathode pour cellule d'electrolyte fondu pour la preparation d'aluminium Expired EP0065534B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81903120T ATE9234T1 (de) 1980-11-26 1981-11-16 Kathode fuer eine schmelzflusselektrolysezelle zur herstellung von aluminium.

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CH873780A CH645675A5 (de) 1980-11-26 1980-11-26 Kathode fuer eine schmelzflusselektrolysezelle zur herstellung von aluminium.
CH8737/80 1980-11-26
DE3045349A DE3045349C2 (de) 1980-11-26 1980-12-02 Kathode für eine Schmelzflusselektrolysezelle zur Herstellung von Aluminium

Publications (2)

Publication Number Publication Date
EP0065534A1 true EP0065534A1 (fr) 1982-12-01
EP0065534B1 EP0065534B1 (fr) 1984-09-05

Family

ID=25703715

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81903120A Expired EP0065534B1 (fr) 1980-11-26 1981-11-16 Cathode pour cellule d'electrolyte fondu pour la preparation d'aluminium

Country Status (11)

Country Link
US (1) US4410412A (fr)
EP (1) EP0065534B1 (fr)
JP (1) JPS57501865A (fr)
AU (1) AU546045B2 (fr)
BR (1) BR8108889A (fr)
CA (1) CA1191816A (fr)
CH (1) CH645675A5 (fr)
DE (1) DE3045349C2 (fr)
SU (1) SU1243629A3 (fr)
WO (1) WO1982001899A1 (fr)
ZA (1) ZA818047B (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2103246A (en) * 1981-07-01 1983-02-16 Diamond Shamrock Corp Electrolytic production of aluminum
CH654031A5 (de) * 1983-02-10 1986-01-31 Alusuisse Verfahren zur herstellung von festkoerperkathoden.
US5472578A (en) * 1994-09-16 1995-12-05 Moltech Invent S.A. Aluminium production cell and assembly
US8747515B2 (en) * 2003-12-27 2014-06-10 Advance Material Products, Inc Fully-dense discontinuously-reinforced titanium matrix composites and method for manufacturing the same
CN109312484B (zh) * 2016-03-30 2022-02-11 美铝美国公司 用于垂直电解池的装置和系统
WO2020072541A1 (fr) * 2018-10-03 2020-04-09 Alcoa Usa Corp. Systèmes et procédés de production électrolytique d'aluminium
CN115383111B (zh) * 2022-08-26 2023-12-19 山东滨州华创金属有限公司 多组元含能合金材料制备工艺及多组元含能合金材料

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US993002A (en) * 1911-02-28 1911-05-23 Russell & Erwin Mfg Co Double-acting floor-hinge.
US3168394A (en) * 1962-05-10 1965-02-02 Arthur F Johnson Purification of aluminum
US3416917A (en) * 1962-11-13 1968-12-17 Gen Electric Superconductor quaternary alloys with high current capacities and high critical field values
US3391999A (en) * 1964-08-17 1968-07-09 Texaco Inc Preparation of metal aluminides
US4071420A (en) * 1975-12-31 1978-01-31 Aluminum Company Of America Electrolytic production of metal
US4187155A (en) * 1977-03-07 1980-02-05 Diamond Shamrock Technologies S.A. Molten salt electrolysis
CH635132A5 (de) * 1978-07-04 1983-03-15 Alusuisse Kathode fuer einen schmelzflusselektrolyseofen.
US4224128A (en) * 1979-08-17 1980-09-23 Ppg Industries, Inc. Cathode assembly for electrolytic aluminum reduction cell
GB2062862B (en) * 1979-11-08 1984-03-14 Sumitomo Metal Ind Fully automatic ultrasonic flaw detection apparatus
US4239606A (en) * 1979-12-26 1980-12-16 Aluminum Company Of America Production of extreme purity aluminum

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8201899A1 *

Also Published As

Publication number Publication date
DE3045349C2 (de) 1982-12-23
CH645675A5 (de) 1984-10-15
ZA818047B (en) 1982-11-24
JPS57501865A (fr) 1982-10-21
AU7709081A (en) 1982-06-03
DE3045349A1 (de) 1982-07-08
EP0065534B1 (fr) 1984-09-05
SU1243629A3 (ru) 1986-07-07
WO1982001899A1 (fr) 1982-06-10
BR8108889A (pt) 1982-10-26
AU546045B2 (en) 1985-08-15
CA1191816A (fr) 1985-08-13
US4410412A (en) 1983-10-18

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