US2975111A - Production of titanium - Google Patents

Production of titanium Download PDF

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Publication number
US2975111A
US2975111A US722408A US72240858A US2975111A US 2975111 A US2975111 A US 2975111A US 722408 A US722408 A US 722408A US 72240858 A US72240858 A US 72240858A US 2975111 A US2975111 A US 2975111A
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United States
Prior art keywords
bath
cathode
titanium
deposition
cell
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Expired - Lifetime
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US722408A
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English (en)
Inventor
Lawrence J Reimert
Erastus A Fatzinger
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New Jersey Zinc Co
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New Jersey Zinc Co
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Priority to US722408A priority Critical patent/US2975111A/en
Priority to BE576598A priority patent/BE576598A/fr
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/06—Operating or servicing
    • 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
    • C25C3/26—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium
    • C25C3/28—Electrolytic production, recovery or refining of metals by electrolysis of melts of titanium, zirconium, hafnium, tantalum or vanadium of titanium

Definitions

  • the improvement of our present invention comprises (a) eflecting circulation of the, bath in contact with the deposition cathode so as to maintain substantially uniform concentrations of the titanium trichloride and titanium dichloride in all portions of the bath which are adjacent and make contact with the deposition cathode and the auxiliary cathode, the auxiliary cathode being in direct communication with the deposition cathode through the medium of the bath therebetween, (b) distributing the electrolyzing current between the deposition and auxiliary cathodes so as to maintain substantially different current densities thereat, the current density at the auxiliary cathode being such as to effect electrolytic reduction of titanium trichloride to titanium dichloride but insufiicient to develop such polarization as to effect significant electrolytic reduction of titanium dichloride to metallic titanium.
  • the molten salt baths which are useful in practicing our invention comprise one or more of the halides of the alkali metals and alkaline earth metals.
  • the chlorides, bromides, iodides and fluorides of sodium, potassium and lithium as well as the same halides of calcium, magnesium, barium and strontium may be used with advantage.
  • an individual halide may be used as a single constituent ba-th, wenow prefer to use a combination of these halides inasmuch as such combinations are characterized by relatively lower melting points than the individual salts.
  • a content of titanium ions having a valence of less than four, i.e. titanous ions, may be established in such a molten salt bath by any one of a number of procedures.
  • titanium dichloride from an extraneous source may be introduced directly into the bath.
  • the titanium dichloride may be formed in situ in the bath by dispersing finely divided metallic titanium throughout the bath and by then bubbling titanium tetrachloride into the bath so that, as a result of the reaction between the metallic titanium and the titanium tetrachloride, titanium dichloride is formed in the bath.
  • the method of our present invention makes it particularly advantageous to establish the requisite lower valence titanium content of the bath without any danger of loss of control of electrolyzing conditions by introducing titanium tetrachloride directly into the bath while maintaining the aforementioned electrolyzing conditions.
  • its presence in the molten halide salt bath in amount of at least about 0.1% by Weight of the bath imparts to the bath the characteristic ofreadily assimilatingtitanium tetrachloride when the latter is brought into contact with the bath.
  • the titanium tetrachloride is advantageouslysupplied to the bath by introducing it directly into the molten bath either with or without a carrier gas such as argon.
  • the cell atmosphere should, of course, be compartmented to maintain separation between the atmosphere above the portion of the bath into which the titanium tetrachloride is introduced and the portion of the bath from which the chlorine is evolved at the anode.
  • the cell is advantageously tightly closed in order to control the .cell atmosphere.
  • the cell electrodes should, of course, be constructed of material which will not introduce extraneous elements into the fused bath.
  • a nonnietallic anode such as graphite or carbon should be used, graphite having been found in practice to be wholly suitable for this purpose.
  • Cathodes and cell walls of nickel, and preferably of corrosion-resistant nickel base alloys, are useful in practicing the invention. At the prevailing cell temperature, the aforementioned cathode materials have been found not to contaminate the deposited metallic titanium to any significant degree and may be used in solid or foraminous form.
  • the relative position between, and the arrangement of, the anode and cathode within the molten salt body should be such that (a) chlorine evolved at the anode will rise in the body of molten bath without entering the body of molten bath adjacent the distal surface of the cathode, (b) the body of molten bath between the anode and the proximate cathode surface and the body of molten bath adjacent the distal surface of the cathode are in communication with one another through a multiplicity of passages, and (c) the distance between the anode and the proximate cathode surface, and hence the resistance of the bath between these surfaces, is sufficiently small to permit electrolytically induced depletion of the titanium content of the molten bath between these surfaces.
  • a closed cell 1 is provided with a fused salt bath 2 in which a cylindrical cathode is preferably but not necessarily immersed.
  • the deposition cathode comprises a cylindrical side wall body portion 3 closed at its lower end withan impervious bottom wall 4 but open at its top end.
  • the side wall portion 3 is composed advantageously of sheet material having large openings 5 punched at intervals throughout its surface and having a lining of screen material 6 secured to the inner surface of the side wall portion.
  • the impervious bottom wall and side wall portions are constructed of sheet metal composed of a corrosion-resistant nickel-base alloy, and the pervious screen 6 is constructed advantageously of Dutch weave wire mesh screen of the same alloy, the screen having 14 mesh per inch in one direction and 120 mesh per inch in the other direction.
  • the anode assembly for the cell comprises a silica dome 8 extending downwardly into the interior of the side walls 3 of the cathode assembly, the lower extremities of the dome being immersed in the fused salt bath 2.
  • the dome is secured to a graphite anode base 9 which is provided with ports 19 and a depending anode section 11 whichis screwed into the anode base.
  • the ports 10 permit escape of chlorine gas from the surface of the bath within the dome 8 into a chlorine efiluent tube 12 which extends through the roof of the cell.
  • the roof of the cell is also provided with a titanium tetrachloride inlet line 13 so as to supply the tetrachloride to the lower portion of the main body portion B of the fused salt bath 2.
  • a separate auxiliary cathode structure is positioned in the main body portion B of the fused salt bath.
  • This structure comprises advantageously a cylindrical body portion 14 supported by a current carrying rod 15 extending into the cell through the cell roof.
  • the body portion of the auxiliary cathode is preferably formed with a relatively large surface area and this has been accomplished in practice by constructing the body portion 14 of wire screen made of 0.08 inch nickel wire and having 4 meshes per lineal inch.
  • other types of foraminous conducting material can be used effectively for the auxiliary cathode provided that the openings in the material are not so fine that they will be blocked by small amounts of titanium metal inadvertently deposited on the material during cell operation.
  • the smooth-surfaced, or even a corrugated surfaced, cell wall is elfective as an auxiliary cathode.
  • the chlorine evolved at the anode leaves the surface of the bath within the confines of the silica dome 8 which thus define a compartment C in the cell atmosphere containing the evolved chlorine.
  • the portion of the cell atmosphere exterior of this chlorine compartment defined by the walls comprises a compartment D into or through which titanium tetrachloride, with or without an inert carrier gas such as argon may be introduced.
  • titanium tetrachloride is absorbed by the body portion B of the bath so that it is added only to that portion of the bath in contact with the auxiliary cathode and with the distal surface of the deposition cathode.
  • the body portion A of the bath is maintained substantially completely depleted of titanium ions by control of the electrolyzing conditions.
  • the unabsorbed argon is withdrawn from compartment D through an exit line 16 in the cell roof.
  • the electrolyzing condition which assures the maintenance of titanium-depletion in the .body portion A of the molten bath between the anode and the proximate cathode surface comprises the use of a voltage sufiiciently high to strip the body portion A of the bath substantially completely of its titanium chloride content.
  • a voltage sufiiciently high to strip the body portion A of the bath substantially completely of its titanium chloride content.
  • a back electromotive force below about 2.2 volts, in this cell is an indication of the presence of-titanium chloride in the body portion A.
  • the back electromotive force is maintained so as to maintain appropriate depletion of titanium ions in the body portion A of the bath either by control of the cell voltage, or, as described in the copending application of Earl W. Andrews, Serial No. 628,117, now abandoned, by controlling the rate at which the titanium tetrachloride is delivered to the cell for assimilation by the molten bath.
  • Measurement of the back electromotive force at intervals of 15 minutes is generally sufliciently frequent to permit the maintenance of a substantially uniform back electromotive force to within about one-tenth of a volt.
  • the electrolyzing condition which assures the establishment and maintenance of the desired concentration and relative proportions of titanium dichloride and titanium trichloride in the main body portion B of the molten bath comprises the maintenance of substantially different current densities at the deposition cathode and at the auxiliary cathode or cathodes.
  • polarization causes the surface-to-bath potential to rise to the point where decomposition of titanium dichloride is attained with resulting electrolytic reduction of the dichloride to titanium metal.
  • the same result would be attained at the auxiliary cathode if the same current density prevailed at this cathode, assuming the bath composition to be substantially the same adjacent both cathodes.
  • the auxiliary cathode effects reduction of titanium trichloride to titanium dichloride
  • the incoming titanium tetrachloride reacts with some of the titanium dichloride to form titanium trichloride, and the remainder of the titanium dichloride is reduced to titanium meta at the deposition cathode.
  • the diflerence between the cathode surface-to-bath potential required to reduce titanium dichloride to titanium metal and that required to reduce titanium trichloride to titanium dichloride is approximately 0.3 volt.
  • the potential applied to a cell containing titanium dichloride and titanium trichl'oride dissolved in fused alkali chlorides is increased from an initial low value, no significant current passes through the electrolyte until the applied potential is sufficient to reduce the trichloride to dichloride and chlorine. Then as the potential is increased the current increases rapidly. At first the increase in current with further increase in applied potential is limited only by the'ohmic resistance of the bath and the cell components.
  • the cathode reaction is influenced by the rate at which trivalent titanium ions can diffuse to the cathode surface.
  • the current becomes equivalent to the rate at which trivalent titanium ions diffuse into the cathode layer, it changes little with increasing applied potential until the cathode becomes sufliciently polarized to permit the reduction of the dichloride to metallic titanium. Beyond this point the current again increases rapidly with increasing applied potential.
  • the electrolyzing current should be distributed between the deposition andauxiliary cathodes so as to maintain substantially different current densities thereat, the lower current density prevailing at the auxiliary cathode and being such as to effect electrolytic reduction of titanium trichloride to titanium dichloride but insuflicient to develop such polarization as to effect electrolytic reduction of titanium dichloride to metallic titanium.
  • the reduction of titanium trichloride to titanium dichloride can be determined and monitored by analyzing a sample of the main body portion B of the bath for its average titanium valence, an average valence of 2.5 to 2.2 indicating proper control of the minimum polarization required in the practice of our invention.
  • the maximum value of the proper range of polarization is, of course, readily indicated by the deposition of metalcathode or as one of two or more auxiliary cathodes.
  • the distribution of electrolyzing current between the deposition and auxiliary cathodes can be effected either by electrical control exterior of the cell or 'by choice of cathode surface area, or by a combination of both means.
  • a wire screen provides, for a given lateral area, a greater bath contact surface area than a smooth nonforaminous surface.
  • melt was considered stripped when the current had dropped below 70 amperes. During stripping, no current was passed to the cell wall, because in the absence of titanium tetrachloride feed there was no need for valence Although the point of introduction of the titanium 5 control.
  • the titanium metal was recovered from the tetrachloride feed into the cell bath has been shown in deposition cathodes and was found to total 5830 grams. the accompanying drawing to be located between the Of this, 4150 grams were coarser than 200 mesh (Tyler auxiliary and deposition cathodes, it must be understood Standard) and upon arc melting yielded an ingot of 106 that the location of this point is not critical. Thus, the Brinell.
  • One sheet extended along the entire cell wall, spaced one Example! inch inwardly therefrom, and the other sheet was coex-
  • a rectangular cell was partially filled with pre-dried tensive with the first but spaced inwardly /2 inch thereeutectic melt.
  • the improvement which comprises effecting circulation of the bath in contact with the distal surface of the deposition cathode so as to maintain substantially uniform concentrations of the titanium trichloride and titanium dichloride in all portions of the bath which are adjacent said distal surface and an auxiliary cathode also in contact with the bath, the average valence of the titanium ions in the bath being within the range of 2.5 to 2.2, the auxiliary cathode being in direct communication with the deposition cathode through the medium of the bath therebetween, the cell atmosphere above the deposition cathode being in direct communication with the cell atmosphere above the auxiliary cathode, distribut- '10 auxiliary cathodes so as to maintain substantially dif ferent current densities thereat, the current density at the auxiliary cathode being such as to effect electrolytic reduction of titanium trichloride to titanium dichloride but insuflicient to develop such polarization as to effect significant electrolytic reduction of titanium dichloride to metallic titanium, the resulting titanium dichloride being available substantially throughout
  • the deposition cathode so as to maintain substantially uniform concentrations ofthe titanium trichloride and titanium dichloride in all portions of the bath which are ing the electrolyzing current between the deposition and adjacent said distal surface and an auxiliary cathode also in contact with the ,bath, the auxiliary cathode being in direct communication with the deposition cathode through the medium of the bath therebetween, the cell atmosphere above the deposition cathode being in direct communication with the cell atmosphere above the auxiliary cathode, distributing the electrolyzing current between the deposition and auxiliary cathodes so as to maintain substantially different current densities thereat, the current density at the auxiliary cathode being such as to eifect electrolytic reduction of titanium trichloride to titanium dichloride with a resulting average titanium valence of 2.5 to 2.2 in the portion of the bath adjacent the deposition and auxiliarycathodes but insufficient to develop such polarization as to effect electrolytic reduction of titanium dichloride to metallic titanium to such extent as to produce at

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  • 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)
US722408A 1958-03-19 1958-03-19 Production of titanium Expired - Lifetime US2975111A (en)

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US722408A US2975111A (en) 1958-03-19 1958-03-19 Production of titanium
BE576598A BE576598A (fr) 1958-03-19 1959-03-11 Procédé de fabrication de titane.

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3067112A (en) * 1959-07-31 1962-12-04 Lonza Chemical And Electrical Method for the electrolytic decomposition of titanium tetrachloride
US3082159A (en) * 1960-03-29 1963-03-19 New Jersey Zinc Co Production of titanium
US3173849A (en) * 1961-01-30 1965-03-16 M S A Res Corp Oxygen generation
US3274083A (en) * 1963-05-13 1966-09-20 Titanium Metals Corp Electrolytic production of titanium
US4381976A (en) * 1980-11-27 1983-05-03 Pechiney Ugine Kuhlmann Process for the preparation of titanium by electrolysis
US4521281A (en) * 1983-10-03 1985-06-04 Olin Corporation Process and apparatus for continuously producing multivalent metals
US4657643A (en) * 1985-03-28 1987-04-14 Pechiney Process for continuously controlling the proportion of metal dissolved in a bath of molten salts and the application thereof to the continuous feed of an electrolysis cell with salts of said metal
US4675084A (en) * 1985-03-19 1987-06-23 Pechiney Process for improving the purity of transition metals produced by electrolysis of halides thereof in a bath of molten salts
US4686025A (en) * 1984-03-12 1987-08-11 Pechiney Apparatus for the production of a metal by electrolyzing halides in a molten salt bath, by a simultaneous continuous double deposit
US5110426A (en) * 1989-10-17 1992-05-05 Compagnie Europeenne Du Zirconium Cezus Method of and an apparatus for introducing at least one halide in the liquid or gaseous state into the bath of a cell for dry electrolysis
US20060207874A1 (en) * 2005-03-18 2006-09-21 Tdk Corporation Plating apparatus
US20090045070A1 (en) * 2006-02-06 2009-02-19 Becker Aaron J Cathode for electrolytic production of titanium and other metal powders

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2741588A (en) * 1951-10-05 1956-04-10 Nat Lead Co Electrolytic production of titanium metal
US2848397A (en) * 1954-07-06 1958-08-19 New Jersey Zinc Co Electrolytic production of metallic titanium

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2741588A (en) * 1951-10-05 1956-04-10 Nat Lead Co Electrolytic production of titanium metal
US2848397A (en) * 1954-07-06 1958-08-19 New Jersey Zinc Co Electrolytic production of metallic titanium

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3067112A (en) * 1959-07-31 1962-12-04 Lonza Chemical And Electrical Method for the electrolytic decomposition of titanium tetrachloride
US3082159A (en) * 1960-03-29 1963-03-19 New Jersey Zinc Co Production of titanium
US3173849A (en) * 1961-01-30 1965-03-16 M S A Res Corp Oxygen generation
US3274083A (en) * 1963-05-13 1966-09-20 Titanium Metals Corp Electrolytic production of titanium
US4381976A (en) * 1980-11-27 1983-05-03 Pechiney Ugine Kuhlmann Process for the preparation of titanium by electrolysis
US4521281A (en) * 1983-10-03 1985-06-04 Olin Corporation Process and apparatus for continuously producing multivalent metals
US4686025A (en) * 1984-03-12 1987-08-11 Pechiney Apparatus for the production of a metal by electrolyzing halides in a molten salt bath, by a simultaneous continuous double deposit
US4675084A (en) * 1985-03-19 1987-06-23 Pechiney Process for improving the purity of transition metals produced by electrolysis of halides thereof in a bath of molten salts
US4657643A (en) * 1985-03-28 1987-04-14 Pechiney Process for continuously controlling the proportion of metal dissolved in a bath of molten salts and the application thereof to the continuous feed of an electrolysis cell with salts of said metal
US5110426A (en) * 1989-10-17 1992-05-05 Compagnie Europeenne Du Zirconium Cezus Method of and an apparatus for introducing at least one halide in the liquid or gaseous state into the bath of a cell for dry electrolysis
US20060207874A1 (en) * 2005-03-18 2006-09-21 Tdk Corporation Plating apparatus
US7540946B2 (en) * 2005-03-18 2009-06-02 Tdk Corporation Plating apparatus
US20090045070A1 (en) * 2006-02-06 2009-02-19 Becker Aaron J Cathode for electrolytic production of titanium and other metal powders

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