US2876180A

US2876180A - Fused salt bath for the electrodeposition of transition metals

Info

Publication number: US2876180A
Application number: US398193A
Authority: US
Inventors: Jr John T Burwell; Quentin H Mc-Kenna
Original assignee: Horizons Titanium Corp
Current assignee: Horizons Titanium Corp
Priority date: 1953-12-14
Filing date: 1953-12-14
Publication date: 1959-03-03
Anticipated expiration: 1976-03-03

Description

Unified tates Patent FUSED SALT BATH FOR THE ELECTRODEPOSI- TION OF TRANSITION METALS Claims. (C1. 204+ This invention relates to the production of transition metals such as titanium and, more particularly, to the production of a fused salt bath containing the transition metal in a form capable of being cathodically deposited by fused salt electrolysis as well as the electrolysis of this bath with the electrodeposition of the transition metal.

In the copending applications of Merle E. Sibert and John T. Burwell, Jr., Serial No. 358,194 and Serial No. 383,401, new Patent No. 2,828,251, there are described methods of producing cathode deposits and cladding d'eposits of certain transition metals including titanium by electrolysis in a fused salt bath wherein the source of the electrodeposited transition metal comprises a solid anode composed of the carbide of the transition metal or a mutual solid solution of the carbide and monoxide of the transition metal or the transition metal in impure metallic form.- Although these methods produce the desired transition metal without impairment of the composition of the fused saltbath, they do require intermittent replenishment of the anode material. Moreover, any oxygen present in the bath, either as an oxide contaminant or as water, is liberated at the anode 'and combines with the transition metal component of the anode material. The resulting -transition metal oxide appears to migrate to the cathode in the form of charged molecules or particles and thus contaminates the transition metal cathode deposit.

We have now found that the advantages of the aforementioned Sibert and Burwell methods may be maintained without the interruption of operation required by replenishment of the anode material provided that the bath composition which is formed during the operation according to the Sibert and Burwell method be produced in advance and be used with a substantially inert "car bonace'ous anode. We have also found that under these latter conditions any oxygen present in the bath is effectively removed in the form of carbon-oxygen gases at the -carbonaceous anode. Moreover, the formation of the electrolysis bath extraneously of the electrolysis operation makes possible a manifold increase in the 'concentration of the transition metal content of the bath and hence a manifold increase in the rate at which the transition metal is electrodeposited as compared with the Sibert and Burwell methods. The method of the present invention is concerned with the production of the aforementioned fused salt bath of the Sibert and Burwell applications and containing the transition metal in a form capable of being cathodically deposited during fused salt electrolysis of the type known as electrowinning. Our novel method comprises fusing either an alkali metal halide or an alkaline earth metal halide, or both, in further admixture with 5 to 50% by weight of a halide of the transition metal. There is then introduced into this fused salt a solid product composed of the carbide of the transition metal or a mutual solid solution of the carbide and the monoxide of the transition metal or the transition metal itself in relatively impure metallic form. Heating of the resulting solid-containing fused salt is continued until the transiice 2 tion metal content of the solid product has been substantially completely converted to the halide of the transition metal in which the metal is present in a lower valence form than in the originally present halide of said metal, and in which the halogen corresponds to the halide of said originally present halide of the transition metal, in solution in the fused salt by reaction with the transition metal halide constituent of the fused halide salt mass. The resulting fused salt bath is then capable of being electrolyzed in the fused state to effect cathodic deposition of the transition metal introduced into the fused salt by the aforementioned thermal-reaction step, andthe resulting spent electrolyte is advantageously returned to the afoiementioned reaction zone as the fused salt with which the solid transition metal product is reacted.

The method of our present invention is equally-applicable to the production of fused salt baths containing any of. the polyvalent transition metals which can be electrodeposited by the method of the aforementioned Sibert and Burwell applications. That is, the present method is capable of producing equally useful fused salt baths containing a lower halide of any of the transition metals titanium, niobium, tantalum and vanadium. Inasmuch as the production of such a fused salt bath containing a titanium halide is representative of the production of the corresponding baths containing the other aforementioned transition metal halides, the following discussion will be directed simply to the titanium'aspect of the invention in the interest of simplicity. However, it must be understood that what is said with respect to the production and use of the titanium bath applies with equal force and effect to the production of corresponding fused salt baths containing the halides of each of the other transition metals niobium, tantalum and vanadium.

The fused salts in which the titanium halide is formed pursuant to our invention may comprise one or more of the alkali halides such as sodium and potassium chlorides, bromides, iodides and fluorides or one or more of the alkaline earth metal halidessuch as calcium, barium, strontium and magnesium chlorides, bromides, iodides and fluorides, or mixtures of one or more of each of these alkali metal halides and alkaline earth metal halides, in further combination with from 5 to 50% by weight of a halide of the transition metal, i. e. a titanium halide. Although simple halides of titanium are useful, such as titanium tetrafluoride, tetrachloride, trichloride, tetrabromide and tetraiodide, we presently prefer to use the complex or double fluorides such as sodium and potassi-ur'n fluot'itanates. The latter are readily soluble in the fused alkali and alkaline earth metal halides, are also relatively non-volatile at bath temperatures within the range of 800 to 1200 C., and can be readily obtained in substantially pure form. In fact, the only important criteria in the choice of the aforementioned salts are their volatility and the fusion point of their mixtures. Thus, we have found that a mixture of sodium chloride and 5 to 50% by weight of potassium fluotitanate is particularly effectiveby virtue of a melting point well below 800 C. and stability at temperatures as high as 1200 C.

The components of the fused salt should be of high purity and should be substantially completely anhydrous in order to minify the introduction of extraneous impurities, including oxygen, into the electrodeposited titanium which is produced by the subsequent electrolysis of the titanium-containing fused salt bath. The alkali metal halides and alkaline earth metal halides are commercially available in a state of purity adequate for use in the practice of the method of our invention. The alkali metal fluotitanates, if used as the transition metal halide in compounding a fused salt mixture in practicing the invention, should be of recrystallized quality in order to avoid the inclusion of the impurities normally present in the fluotitanates as initially produced.

Fusion of the components of the salt bath is carried out under conditions which will insure the absence of atmospheric oxygen and moisture. Thus, we have found it advantageous to carry out this fusion in a closed reaction vessel in which an inert atmosphere of argon or the like may be maintained. The salt in the reaction vessel may be heatedby any means which will not introduce impurities ther'einto. For example, the exterior'of the reaction vessel, which should be formed of a corrosion resistant material such as graphite or the like, may be heatedby any suitable means. On the other hand, the saltmay be heated by electric resistance elements within the reaction vessel itself or by means of an alternating current passing "through electrodesimmersed in the salt. The salt should be heated to a temperature at least50 C.,' and advantageously about 100 C., above its fusion point in order to insure adequate fluidity of the fused mass. In general, the fusion points of the various bath compositions described hereinbefore are such that an ultimate bath temperature of about 750 C. will insure the requisite bath fluidity. Temperatures from about 750 to 1300 C., and preferably within the range of 800 to 1200 C., are effective in promoting the reaction between the titanium halide component of the bath and the solid titaniferous material, higher temperatures within these ranges promoting more rapid and more complete reaction.

The introduction of the titanium component of the titaniferous material into the aforementioned fused salt mixture is assured by simply immersing the solid titaniferous material in the bath. The solid titaniferous materials useful for this purpose are those in which the titanium is present as an interstitial rather than a substitutional solid material. These titaniferous materials include, as described in the aforementioned Sibert and Burwell "applications, titanium carbide, a mutual solid solution of titanium carbide and titanium monoxide, and metallic titanium in relatively impure form. In the carbide, for example, the carbon and titanium are present in interstitial atomic arrangement rather than in the form of a compound.v Thus, in each of these titaniferous materials the titanium of the carbide or impure metal appears to exist as the metal itself. Although the dense form of the titanium carbide described in the aforementioned application may be used satisfactorily in practicing our invention, we presently prefer to produce the carbide in a less dense form so that it will have a degree of porosity which will promote more rapid reaction with the titanium halide component of the fused salt mixture. The production of such a less dense form of the titanium carbide is described in the copending application of Bertram C. Raynes, Merle E. Sibert and John T. Burwell, In, Serial No. 398,191, filed concurrently herewith, and which has now issued as United States Patent 2,813,069, and the lower practical limit for the density of such a porous carbide is that which will insure adequate mechanical strength for convenient handling. However, there is no lower limit for the density of the carbide, the carbide-monoxide solid solution or the impure metal with respect to their reactivity and utility,

The solid titaniferous material may be introduced into the fused salt bath either in the form of relatively large lumps or in the form of smaller lumps of about ,41. inch maximum dimension or even in the form of finely divided particles. When the solid titaniferous material is added in relatively coarse form, it is advantageous to suspend it in the bath in a graphite basket, but the finely divided solid material may be simply charged directly to the bath where it readily reacts with the titanium halide component of the bath with resulting extraction, and dissolution in the bath,' of the titanium component of the titaniferous material.

Extraction of the titanium component of the solid titaniferous material, and its resulting dissolution in the fused salt bath, is effected by reaction between the titanium halide component of the bath and the titanium component of the aforementioned type of solid titaniferous material. In this reaction the metalliferous titanium component of the solid material is oxidized to a titanium compound and the titanium halide component of the bath is correspondingly reduced to a lower valence titanium halide. For this reason, then, the practice of the invention is restricted to the use of transition metals capable of existing in at least two ditferent valence states in the form of halide salts, and this requirement is satisfied only by titanium, niobium (columbium), tantalum and vanadium. With each of these elements, its halide which is incorporated in the fused salt is the higher or highest valence form, and the final bath composition containing the transition element in the form of one of its lower valence halides. It will be readily understood, therefore, that the amount of the transition metal which is extracted from the solid transition metal material is a function of the amount of the transition metal higher valence halide which is incorporated in the initial salt mixture and the difference in valence of the transition metal in the two forms of its halide which predominate in the bath before and after the aforementioned reaction. In the case of titanium, each mol of alkali metal fluotitanate (inwhich the titanium has the valence of four) will extract one-third mol of titanium from the solid titaniferous material.

The resulting fused salt bath containing the extracted titanium component of the solid titaniferous material is capable of being electrolyzed in the fused state with the resulting electrodeposition of the extracted titanium component in the form of titanium metal. In transferring the fused salt bath to an electrolytic cell, unless the bath is formed in situ in the cell, it is advantageous to filter the bath to remove any residual solid such as carbon or unreacted titaniferous material. The transfer of the fused salt may be carried out through pipes of graphite or other inert material communicating between the thermal reactor and the electrolytic cell. The electrolytic cell equipment, and the electrolytic conditions such as cell voltage and cathode density for this electrolysis, are the same as set forth in the aforementioned Sibert and Burwell applications, although as described hereinafter there is a notable advantage in using graphite or other solid carbonaceous material as the anode. The primaryproduct of the electrolysis is titanium metal which is deposited on the cell cathode either as a recoverable titanium deposit or as a titanium cladding layer on a base metal cathode material. The halogen associated in the form of a salt with the extracted component of the solid titaniferous material is also liberated at the anode but re-combines with the lower valence titanium halide until the concentration of the higher valence titanium halide has been reconstituted. The resulting spent cell bath, after completion of this electrolytic decomposition of the extracted titanium component of the bath, is therefore substantially identical with the original fused halide salt with which the "titaniferous solid material was reacted, and thus the spent cell bath may be returned directly to the fused salt-solid material reactor for a completely cyclic operation. If desired, however, the production of the titanium-containing bath and its subsequent electrolysis may take place successively and repeatedly in a single vessel which thus serves both as the reactor and as the electrolytic cell.

There is also formed at the anode, during electrolysis of the extracted titanium-containing fused salt bath, a small amount of carbon monoxide (and occasionally a still smaller amount of carbon dioxide) as aresult of the combination of the carbon component of the carbonaceous anode and the oxygen liberated at the anode from any oxide or moisture contained in the fused salt bath. Thus, the electrolysis with a carbonaceous anode of a titanium-containing bath produced pursuant to the present invention functions as a purification operation for the removal of contaminating oxygen. This purification aspect of the invention is particularly valuable where the solid titaniferous material which is reacted with the fused-halide salt comprises relatively impure titanium metal produced from a previous electrolytic operation and characterized by the presence of oxygen as its principal objectionable impurity. It will be readily appreciated, accordingly, that the titanium metal deposited on the cathode during this electrolytic operation may be used as the solid titaniferous material which is reacted with the fused halide salt, and in this way the subsequently repeated deposition of the titanium metal by electrolysis produces the transition metal in a purer form than that originally cathodically deposited. The practice of themethod of our invention thus makes possible the production of titanium metal having a hardness as low as Rockwell A-50 and even lower.

The practice of the invention is illustrated by the following specific examples:

Example I p Titanium carbide was prepared by heating to about 2000 C. under a vacuum a mixture of pure titanium dioxide and an amount of carbon 2 to 3% over that theoretically required to reduce the oxide to the carbide. The resulting carbide was then ground to minus 325 mesh in water in an iron ball mill. The slurry obtained was treated with 20% hydrochloric acid until all reaction ceased. The milled carbide was then washed with water until all the acid and the by-products from the acid had been removed, after which the product was evaporated to dryness.

. A mixture was then prepared consisting of 100 parts of milled carbide, 1.5 parts of methyl cellulose having a viscosity of 4000 centipoises, 3 parts of calcium fluoride, and approximately 12 parts of water. The ingredients were thoroughly mixed until completely dispersed. Rods 1 inch in diameter were produced by extruding the resulting plastic mass through an extrusion orifice. After air drying for 24 hours, the rods were placed in a graphite crucible which was induction heated under vacuum conditions to a temperature of about 20002l00 C., for a period of about of an hour. Within a few minutes after reaching this temperature, the pressure conditions within the heating furnace had reached a steady state and the pressure was not allowed to increase substantially during the %-hour' heat treatment.

A thermal reactor was provided consisting of a cylindrical graphite crucible. This crucible was placed in a gas-tight cell provided with an electrical resistance heating element and with an inlet and outlet for argon gas. The outlet line was provided with a valve to control the argon flow through the cell and prevent back-diifusion of air into the cell. The cell was thus supplied with argon carefully purified of air and water vapor.

A salt mixture was prepared consisting of a mixture of 100 parts of sodium chloride and 16 parts by weight of recrystallized potassium titanium fluoride (in which the titanium has a valence of four). The metal carbide lumps were first added to the crucible and then the salt mixture was added. The cell was carefully evacuated and flushed with argon three times and after a third filling of argon it was heated to 859 C. The reactor cellwas held at this temperature for 6 hours as measured from the time when the salt had become entirely molten. It was then cooled toroom temperature while maintaining the argon atmosphere in the cell. The frozen salt cake, which was found to have a brownish to purplish color as contrasted to the water-white color of the initial constituents, was removed from the crucible and the bottom portion of the cruciblecharge containing unreacted 6 carbide lumps was separated from the remainder of the salt cake.

The resulting salt cake was then introduced into an electrolytic cell consisting of a cylindrical graphite container. This cell was fitted with electrical connections and inlets for pure argon gas so that electrolysis could be carried out under a controlled atmosphere. The cell also contained a chamber on top which was separated from both the outside atmosphere and the cell atmosphere by gas-tight partitions through which a cathode could be inserted and removed. This chamber provided a means for cooling the cathode deposit in an inert atmosphere. The cell was evacuated and flushed with argon three times after which it was heated to approximately 975 C. until the salt was entirely molten.

At this stage a graphite -rod was inserted into the center of the bath through the gas-tight opening in the top of the cell, and pre-electrolysis was begun by applying a voltage of 1.5 volts between this rod as the cathode and the crucible as the anode. The current was initially approximately 10 amperes but after about 1 hour it fell rather abruptly to about /3 of this value, thus indicating that most of the oxygen-containing impurities in the cell bath had been discharged. At this point the graphite rod was withdrawn from the bath and was-replaced by a cathode consisting of a steel cone supported by a nickel shank which was sleeved with graphite in the region where it leaves the controlled atmosphere zone of the cell. This cathode, like the original graphite rod, was tightly sealed against leakage of air where it emerged from the cell. The temperature of the cell was lowered to 850 C. As soon as the cathode was immersed in the bathgth'e cell voltage was applied between it and the crucible anode and the electrolysis was thus begun while promptly lowering the cell bath temperature to about 850 C. The cellvoltage was 2.2 volts and produced a cell current of about 50 amperes which corresponded to a cathode current density of about amp/dun The electrolysis was continued for a total of about 60 ampere-hours after which the cathode was withdrawn to cool in the gas-tight chamber above the cell through which purified argon was also kept flowing. After coo-ling in the removal chamber, the cathode deposit was cracked off the cathode.

The separated cathode deposit was then dry mortared and soaked in 1000 cc. of hot water containing .1 to .15% of H 0 This water was decanted and replaced by 1000 cc. of fresh similar H O -hot water solution, and this washing and decanting operation was repeated for a total of six washings. The deposit was then wet mortared to break it down completely, following which the above-described washing step was repeated ten more times. After the lastdecantation, the cathode depoSit was rinsed once in plain cold water and was then covered with cold concentrated HCl for 20 minutes. The acid was then rinsed off with water, the water was rinsed off with alcohol, and the finely divided solid product was then air dried in an oven. The resulting metal powder was melted into an ingot under an argon atmosphere. The yield of titanium in the form of this ingot corresponded to a cell current eificiency of about and had a hardness of 56 on the Rockwell A scale.

The electrolytic bath was returned from the electrolytic cell to the thermal reactor to which a fresh lot of metal carbide pellets had been added and the entire process was repeated. The product of the second electrolysis gave a similar yield having a Rockwell A hardness of 53. The whole process was again repeated using the same electrolytic salt bath in the reactor, and the resulting product had a Rockwell A hardness of 50.

Example 11 The procedure described in Example I was repeated with the only changes being that the thermal reaction and the electrolysis were carried out in the same cell and The operation described in Example I was repeated except that the bath consisted of 50 parts of NaCl, 50 parts of KCl and parts of recrystallized potassium titanium double fluoride (in which the titanium has a valence of four) and that the temperature of electrolysis was 800 C.

Example IV 'The operation described in Example I was repeated except that the pre-electrolysis step was omitted. The hardness of the resulting titanium ingot was R 68. After the bath had been recycled through the thermal reaction step, the second ingot had a hardness of R 56 and after recycling again through the complete operation the hardness of the third ingot was R 50. After a fourth similar cycle, the hardness of the titanium ingot was R 48.

- Example V The operation described in Example I was repeated substituting 15 parts of recrystallized potassium niobium fluoride (KgNbFq) for the titanium salt used in Example I. The resulting niobium metal was of high purity.

Example VI The operation described in Example I was repeated substituting 15 parts of recrystallized potassium tantalum fluoride (K TaF- for the titanium salt used in Example I. The resulting tantalum metal was of high purity.

Example VII The operation described in Example I was repeated substituting 15 parts of recrystallized potassium vanadium fluoride (K VF for the titanium salt used in Ex ample -I. The resulting vanadium metal was of high purity.

It will be appreciated, accordingly, that the method of our invention makes possible a highly efficient recovery of the aforementioned transition elements by a combination of thermal reaction and electrolysis. This combination is particularly amenable to commercial scale operation because the thermal reaction and electrolysis may be carried out simultaneously in separate and independently controlled reactionzones. Our method is also characterized by the fact that the fused salt or salt mixtures used in practicing the invention may be recycled between the thermal reaction and electrolysis operations. Therefore, the only consumable reactant is the solid titaniferous material. Any solid titaniferous material remaining unconsumed at the end of each extraction reaction period, and generally this reaction is effected within one to six hours depending upon the temperature of the fused salt and the degree of subdivision of the solid titaniferous material, may be readily separated from the salt bath in the reaction zone and recovered for reuse. Such recovery is advantageously effected by mechanically agitating the unused solid titaniferous material, together with any residual carbon particles from the titanium carbide, in order to separate from the useful titaniferous component any residual non-usable material such as carbon. The solid titaniferous component of this mechanically agitated mixture may then be separated by any conventional means so that it may be returned to the thermal reaction stage. Thus, except for relatively small make-up quantities of the salt component of the fused bath to compensate for mechanical losses, the only win sumable raw material comprises the solid titaniferous material which is used as one of the reaction components. This economy of raw materials, coupled with the con tinuity of operation and the high degree of purity of its primary product (the transition metal such as titanium), characterizes our method as one pre-eminently suitable for commercial scale operation.

We claim:

1. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state with the resulting catholic deposition of the transition metal which comprises fusing a least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of a halide,

of the transition metal, capable of being retained in said fused halide salt and in which the transition metal is present in a higher valence form; introducing into the re sulting fused salt mass a solid product of the group consisting of a carbide of the transition metal, a mutual solid solution of the carbide and of the monoxide of the transition metal and the transition metal in relatively impure metallic form, continuing the heating of the fused halide salt-solid product mixture until the transition metal content of said solid product has been substantially completely converted to the halide thereof by reaction with the fused halide salt mass, and recovering separately from any residual bath-insoluble component of the added solid product the resulting transition metal halide-containing fused salt bath in which the transition metal is present in a valence form lower than the higher valence form in which it was originally present in the transition metal halide provided for the fused salt bath prior to introduction therein of said solid transition metal material.

2. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of an alkali metal double fluoride of the transition metal, in which the transition metal is present in a higher valence form; introducing into the resulting fused salt mass a solid product of the group consisting of a carbide of the transition metal, a mutual solid solution of the carbide and of the monoxide of the transition metal and the transition metal in relatively impure metallic form, continuing the heating of the fused halide salt-solid product mixture until the transition metal content of said solid product has been substantially completely converted to the halide thereof by reaction with the fused halide salt mass, and recovering separately from any residual bath insoluble component of the added solid product the resulting transition metal halide-containing fused salt bath in which the transition metal is present in a valence form lower than the higher valence form in which it was originally present in the transition metal halide provided for the fused salt bath prior to introduction therein of said solid transition metal material.

3. The method of forming a fused salt bath containing a, halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 5 0% by weight of a halide of the. transition metal, capable of being retained in said fused halide salt and in-which the transition'metal is present in a higher valence form; introducing into the resulting fused salt mass a solid product of the group consisting of a carbide of the transition metal, a mutual solid solution of the carbide and of the monoxide of the transition metal and the transition metal in relatively impure metallic form, continuing the heating of the fused halide salt-solidproduct mixture at a temperature within the range'of 800-1200 C. until the transition metal content of said solid product has been substantially completely converted to'the halide thereof by' reaction with the fused halide salt mass, and recovering separately from any residual bath-insoluble component of the added solid product the resulting transition metal halide-containing fused salt'bath.

4, The method of forming a fused salt bath containing a titanium halide and capable of being electrolyzed in the fused state with the resulting cathodic deposition of titanium metal which comprises fusing at least one halide salt'of the group consisting of alkali and alkaline earth metal halides in combination with from to 50% by weight of an alkali metal-titanium double fluoride, introducing into the resulting fused salt mass a solid product of the group consisting of titanium carbide, a mutual solid solution of titanium carbideand of titanium monoxide and titanium metal in relatively impure metallic form, continuing the heating of thefused halide salt-solid product mixture until the titanium content of said solid product has been substantially completely converted to the halide thereof by reaction with the fused halide salt mass, and recovering separately from any residual bath-insoluble component of the added solid product the resulting titanium halide containing fused salt bath.

5. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of a halide of the transition metal, capable of being retained in said fused halide salt and in which the transition metal is present in a higher valence form; introducing into the resulting fused salt mass a solid product of the group consisting of a carbide of the transition metal, a mutual solid solution of the carbide and of the monoxide of the transition metal and the transition metal in relatively impure metallic form, continuing the heating of the fused halide salt-solid product mixture until the transition metal content of said solid product has been substantially completely converted to the halide thereof by reaction with the fused halide salt mass, recovering separately from an residual bath-insoluble component of the added solid product the resulting transition metal halide-containing fused salt bath in which the transition metal is present in a valence form lower than the higher valence form in which it was originally present in the transition metal halide provided for the fused salt bath prior to introduction therein of said solid transition metal material, and electrolyzing the recovered fused salt bath in the presence of a carbonaceous anode to effect electrodeposition of the transition metal component of the transition metal halide introduced into the fused salt from the solid transition metal product.

6. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of a halide of the transition metal, capable of being retained in said fused halide salt and in which the transition metal is present in a higher valence form; introducing into the resulting fused salt mass a solid product of the group consisting of a carbide of the transition metal, a mutual solid solution of the carbide and of the monoxide of the transition metal and the transition metal in relatively impure metallic form, continuing the heating of the fused halide salt-solid product mixture until the transition metal content of said solid product has been substantially completely converted to the halide thereof by reaction with the fused halide salt mass, recovering separately from any residual bath-insoluble component of the added solid product the resulting transition metal halide,- containing fused salt bath in which the transition metal is present in avalence form lower than the higher valence form in which it was originally present in the transition metal halide provided for the fused salt bath prior to introduction therein of said solid transition metal material, electrolyzing the recovered fused salt bath in the presence of a carbonaceous anode to effect electrodeposition of the transition metal component of the transition metal halide introduced into the fused salt from the solid transition metal product, and using the resulting spent electrolyte as the fused salt mass with which the solid transition metal product is reacted.- I

7. The method of forming a fused salt bath containing a titanium halide and capable of being electrolyzed in the fused state with the resulting cathodic deposition of titanium metal which-comprises fusing at-least one halide salt of the group consisting alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of an alkali metal-titanium double fluoride, introducing into the resulting fused salt mass a solid product of the group consisting of titanium carbide, a

mutual solid solution of titanium carbide and of titanium monoxide and titanium metal in relatively impure metallic form, continuing the heating of the fused halide salt-solid product mixture until the titanium metal content of said solid product has been substantially completely converted to the halide thereof by reaction with the fused halide salt mass, recovering separately from any residual bath-insoluble component of the added solid product the resulting titanium halide-containing fused salt bath, electrolyzing the recovered fused salt bath in the presence of a carbonaceous anode to effect electrodeposition of the titanium component of the titanium halide introduced into the fused salt from the solid titaniferous material, and using the resulting spent electrolyte as the fused salt mass with which the solid titaniferous material is reacted.

8. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of beling electrolyzed in the fused state between an inert non-consumable anode and a cathode with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of a halide of the transition metal, capable of being retained in said fused halide salt and in which the transition metal is present in a higher valence form; introducing into the resulting fused salt mass a solid carbide of the transition metal with resulting conversion of the transition metal component of the carbide to a halide thereof by reaction with the fused halide salt mass, and electrolyzing the resulting fused salt bath between an inert non-consumable anode and a cathode to effect electro-disposition of the transition metal at said cathode.

9. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state between an inert non-consumable anode and a cathode with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of 11 the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of a halide of the transition metal capable of being retained in said fused halide salt and in which the transition metal is present in a higher valence form in a reaction zone, introducing into the resulting fused salt mass in said reaction zone a solid carbide of the transition metalwith resulting conversion of the transition metal component of the carbide to a halide thereof by reaction with the fused halide salt mass, transferring the resulting fused salt bath to an electrolyzing zone out of direct contact with the solid carbide, and electrolyzing said fused salt bath between an inert non-consumable anode and a cathode in said electrolyzing zone to effect electrodeposi tion of the transition metal at said cathode.

10. The method of forming a fused salt bath containing a halide of a polyvalent transition metal of the group consisting of titanium, niobium, tantalum and vanadium and capable of being electrolyzed in the fused state between an inert non-consumable anode and a cathode with the resulting cathodic deposition of the transition metal which comprises fusing at least one halide salt of the group consisting of alkali and alkaline earth metal halides in combination with from 5 to 50% by weight of a halide of the transition metal capable of being retained in said fused halide salt and in which the transition metal is present in a higher valence form in a reaction zone, introducing into the resulting fused salt mass in said reaction zone a solid carbide of the transition metal with resulting conversion of the transition metal component of the carbide to a halide thereof by reaction with the fused halide salt mass, continuously transferring the resulting fused salt bath as it is produced to 'an electrolyzing zone out of direct contact with the solid carbide, electrolyzing the resulting fused salt bath between an inert non-consumable anode and a cathode to effect electrodeposition of the transition metal at said cathode, and continuously returning a portion of the resulting titanium-depleted fused salt bath from the electrolyzing zone to the reaction zone for further reaction with the solid carbide therein.

References Cited in the file of this patent UNITED STATES PATENTS,

OTHER REFERENCES Journal of Metals, September 1956, Electrolytic Titanium, by Sibert et al., p. 1165.

The Chemical Age (London), May 5, 1928, page 33, article by Dyson.

Chemical Abstracts, vol. 44 (1950), page 5228.

Claims

1. THE METHOD OF FORMING A FUSED SALT BATH CONTAINING A HALIDE OF A POLYVALENT TRANSITION METAL OF THE GROUP CONSISTING OF TITANIUM, NIOBIUM, TANTALUM AND VANADIUM AND CAPABLE OF BEING ELECTROLYZED IN THE FUSED STATE WITH THE RESULTING CATHOLIC DEPOSITION OF THE TRANSISTION METAL WHICH COMPRISES FUSING A LEAST ONE HALIDE SALT OF THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METAL HALIDES IN COMBINATION WITH FROM 5 TO 50% BY WEIGHT OF A HALIDE OF THE TRANSITION METAL, CAPABLE OF BEING RETAINED IN SAID FUSED HALIDE SALT AND IN WHICH THE TRANSITION METAL IS PRESENT IN A HIGHER VALENCE FORM; INTRODUCING INTO THE RESULTING FUSED SALT MASS A SOLID PRODUCE OF THE GROUPE CONSISTING OF A CARBIDE OF THE TRANSITION METAL, A NUTUAL SOLIDE SOLUTION OF THE CARBIDE AND OF THE MONOXIDE OF THE TRANSITION METAL AND THE TRANSITION METAL IN RELATIVELY IMPURE METALLIC FORM, CONTAINUING THE HEATING OF THE FUSED HALIDE SALT-SOLID PRODUCT MIXTURE UNTIL THE TRANSITION METAL CONTENT OF SAID SOLID PRODUCE HAS BEEN SUBSTANTIALLY COMPLETELY CONVERTED TO THE HALIDE THEREOF BY REACTION WITH THE FUSED HALIDE SALT MASS, AND RECOVERING SEPARATELY FROM ANY RESISTANCE BATH-INSOLUBLE COMPONENNT OF THE ADDED SOLID PRODUCT THE RESULTING TRANSITION METAL HALIDE-CONTAINING FUSED SALT BATH IN WHICH THE TRANSITION METAL IS PRESENT IN A VALENCE FORM LOWER THAN THE HIGHER VALENCE FORM IN WHICH IT WAS ORIGINALLY PRESENT IN THE TRANSITION METAL HALIDE PROVIDED FOR THE FUSED SALT BATH PRIOR TO INTRODUCTION THERIN OF SAID SOLID TRANSITION METAL MATERIAL.