US2837426A

US2837426A - Cyclic process for the manufacture of titanium-aluminum alloys and regeneration of intermediates thereof

Info

Publication number: US2837426A
Application number: US485325A
Authority: US
Inventors: Kamlet Jonas
Original assignee: National Destillers and Chemical Corp
Current assignee: Millennium Petrochemicals Inc
Priority date: 1955-01-31
Filing date: 1955-01-31
Publication date: 1958-06-03
Anticipated expiration: 1975-06-03

Description

United States "Patented June 3, 1958 CYCLIC PROCESS FOR THE MANUFACTURE OF TITANIUM-ALUMINUM ALLOYS AND REGEN- ERATION F INTERMEDIATES THEREOF No Drawing. Application January 31, 1955 Serial No. 485,325

14 Claims. (Cl. 75175.5)

This invention relates to a cyclic process for the manufacture of titanium-aluminum alloys and the regeneration of the intermediates of said process. More particularly, it relates to a process for the manufacture of titanium-aluminum alloys containing from 0.1% to 95% of titanium, and for the processing of the by-products of said process to regenerate the intermediate chemical compounds required for the manufacture of said alloys.

Manchot and Richter (Annalen 357, 140-144 (1907)) reacted potassium fluotitanate with metallic aluminum in quantity far in stoichiometric excess of that required by the equation:

at advanced temperatures, and obtained a titaniumaluminum alloy containing 9.4% of titanium. In my co-pending application Serial No. 382,206, filed September 24, 1953, now Patent No. 2,785,971, granted March 19, 1957, I have shown that alloys containing from 53% to 95% of titanium (the remainder being aluminum) may be obtained by the reaction, at advanced temperatures, of alkali metal fiuotitanates with aluminum in quantities within a closely specified range. I now find that alloys of titanium and aluminum containing from 0.1% to 95 of titanium can be obtained by the reaction, at advanced temperatures, of alkali metal fluotitanates with metallic aluminum, employing per gramrnole of alkali metal fluotitanate (i. e. per 207.9 grams of Na TiF or per 175.8 grams of LigTlFs, or per 240.1 grams of K TiFe), from 38.5 grams to 47.9 kilograms of metallic aluminum, and that this reaction may be adapted to a cyclic regeneration of the reagents thereof.

This very broad range of titanium contents in the alloys obtained requires somewhat difierent modes of operating, depending on the melting point of the alloy to be prepared. The following chart represents the approximate melting point of the series of alloys preferable by the process of this invention:

Percent Ti: Approximate melting point, C. 0.1 to 1 660 to700 30 1280 37.3 (TiAl 1350 40 1370 Binary alloys containing up to 37.28% of titanium consist of crystals of titanium aluminide (TiAl dispersed in excess aluminum. The binary alloy containing 37.28% of titanium corresponds to TiAl in composition. Binary um metal.

2 alloys containing 37.28% to 53% of titanium consist of crystals of titanium aluminide dispersed in excess titani- Binary alloys containing more than 53% of titanium comprise simple solutions of the aluminum in the titanium and do not form intermetallic compounds. Formation of alloys containing up to of titanium proceeds at a rapid rate. As arule, the more aluminum that is used (within the limits above described), the more rapid and complete is the reaction between the alkali metal fiuotitanate and the aluminum, and the formation of the titanium-aluminum alloy. As the amount of aluminum is decreased, the reaction with the alkali metal fiuotitanate becomes slower, and there is a greater tendency for incomplete reduction of the alkali metal fluotitanate with formation of divalent and trivalent titanium compounds. By prolonged heating, however, alloys con' taining up to 95 titanium may however be obtained by this method.

The temperatures at which this reaction may be efiected may vary quite widely. It is desirable to have at least one of the reagents (i. e. the aluminum) in a molten state, and preferably both the aluminum and the alkali metal fiuotitanates should be in a molten state. Thus, the lower limit of temperature for this reaction is set by the melting point of aluminum, i. e. 660 C. Both reagents are molten in the range of -1100 C. The upper limit of temperature for this reaction is set by the boiling point of aluminum (1800 C.) and the melting point of the alloy being prepared. It is desirable, at the conclusion of the reaction, to be able to separate a molten regulus of titanium-aluminum alloy from the concomitant slag consisting of molten alkali metal aluminum fluoride and aluminum fluoride. Thus, the temperature range for this reaction may be given as 660 C. to 1800 C., with a'preferred range between 900 C. and 1550 C., depending on the composition of the alloy being prepared. In the case of the higher melting alloys, it may be found preferable to allow the reaction mixture of titanium-aluminum alloy and slag to cool and solidify and thereafter to separate the crystallized slag (consisting of alkali metal fiuoaluminate and aluminum fluoride) from the alloy by leaching or dissolving the former in Water and separating the resultant solution from the insoluble alloy (e. g. by filtering or centrifuging).

A preferred method for effecting this step of the invention is to mix the calculated quantity of molten aluminum and alkali metal fluotitanate in a refractorylined crucible in an induction furnace, and then to heat the mixture with agitation, if necessary, until the reaction is complete and a final temperature between 900 C. and 1550 C. is attained at which the salt mixture (i. e. the slag) is molten and the binary alloy may or may not be molten. If both components of the reaction mixture are molten, they may be separated by decantation in the usual manner. If the slag is molten and the alloy is solid, they may be separated by decantetion or filtration (e. g. by screening through a metal mesh filter), in the usual manner. 1

Another preferred method of effecting this step is to permit the reaction mixture of slag and alloy to cool and solidify, and thereafter to separate these components by comminution and screening or (as above described, by leaching the water-soluble slag from the insoluble alloy by treatment with water. Graphite-lined crucibles are, as. a rule, suitable for effecting the reaction of this invention since they are not attacked by the reagents at the indicated reaction temperatures.

Although some of the alkali metal fluotitanates are known to form crystalline hydrates at lower temperatures, they are, of course, employed as anhydrous salts at the temperature-ranges involved in the process of this i-n 3 vention. Since the aluminum is always employed in the molten state, it need not be comminuted prior to addition to the reaction mixture, but may be added to the crucible as bar or pig aluminum or in the molten state.

The titanium-aluminum alloys thus prepared have a wide range of utility in industrial metallurgy. They are employed to refine grain structure, remove gas occlusions,

increase tensile strengths, increase resistance to leaking of castings, improve mechanical properties, decrease the electrical conductivity, increase impact resistance, increase resistance to acids, saline and other aggressive solutions, increase corrosion resistance, improve castings and lower the casting temperatures of various metals and alloys (Journ. Inst. Metals 1930, 531; Chem. Zentr. 19371, 2002; 1944I, 242; Alluminio 16, (1947); U. S. Patents 2,252,241 and 2,376,681; Metallurstschaf-t 21, 683 (1942); Chimie & Industrie 26, 338 (1932); Aluminum 17, 79 (1934); 16, 635 (1937); 20, 452 (1938); 26, 2 (1944); British Patent 473,916; Zeit. anorg. Chem. 150, 26 (1926); Comptes rendus 220, 690 (1945); Journ. Metals 3 Trans. 1143 (1951).

Thus, weldable titanium alloys containing 5% aluminum and 2.5% tin show good ductility with yield strengths of about 110,000 p. s. i. Other titanium alloys containing 6% aluminum and 4% vanadium show excellent hightemperature properties with reported yield strengths of 190,000 p. s. i. and 14% elongation at room temperature. Titanium alloys containing of aluminum demonstrate superior elevated-temperature properties.

Similarly, alloys containing of aluminum and 5% of titanium, preparable by the process of this invention, show excellent corrosion resistance. The development of such titanium-aluminum alloys is discussed by Gonser (Industrial and Engineering Chemistry 42, 222-226 (1950) and by Hansen and Kessler (Society of Automotive Engineers, January 12-16, 1953), and by Larsen, Swazy, Busch and Freyer in the United States Officeof Naval Research, Rept. Titanium Symposium, -124 (1949).

A very important industrial outlet for the titanium aluminum alloys of this invention is as a partial or total replacement of the manganese alloys employed for sulfur control in the manufacture of steel (Roach and Stewart, Iron Age, June 4 and June 11, 1953; Goldschmidt and (K/cil, U. S. Patents 1,075,782 (1913) and 1,136,670

Another highly important industrial outlet for the titanium-aluminum alloys of this invention is as intermediates in the manufacture of pure metallic titanium.

In my co-pending patent application Serial No. 382,206, filed September 24, 1953, I describe a process whereby alloys of titanium and aluminum containing more than 53% of titanium (and therefore free of the intermetallic compound TiAl are leached with aqueous alkali solutions whereby the aluminum is separated from the alloy and metallic titanium remains behind.

Pure metallic titanium may also be obtained from such alloys of titanium and aluminum containing more than 53% titanium (devoid of the intermetallic compound TiAl by distilling off the aluminum (preferably under reduced pressure). A preferred procedure involves the removal of the aluminum from the alloy by heating in the presence of an aluminum halide (e. g. AlFg, AlCl AiBl'g), whereby the subhalide is formed (e. g. AlF, AlCl, AlBr) and distilled from the alloy under reduced pressure. This technique is described by Cueilleron and Pascaud (Comptes rendus a 1 Academic des Sciences 233, 745- 747 (1951), ibid, 235, 1220-1221 (1952) and by Ramamurthy (Journ. Scien. lndustr. Research (India) 11B, 545-546 (1952), and isa modification of the wellknown subhalide process for the recovery of aluminum from alloysand for the refining of aluminum from scrap and secondary metal. The alloy or aluminum-containing scrap is heated to 1000-1200 C. and the aluminum 4 l trihalide (usually AlCl is added, whereby the aluminum monohalide (AlCl) distills over. The distilling vapor is passed through a condenser at 500-600 C. whereby the aluminum monohalide dismutates to the aluminum trihalide and metallic aluminum. The aluminum trihalide is in the vapor state (AlCl sublimes at 192 C.) and may be recirculated through the alloy or aluminum-containing scrap, whereas the aluminum formed in the dismutation is recovered in a compact form and in a state of high purity. Thus, by the circulation of the sublimed AlCl through the alloy, the process can be operated on a continuous or semicontinuous basis. (Zintl, Krings, Banning, Morawietz and Gastinger, Zeit. anorg. allgem. Chemie 245, 8 (1940), German Patent 742,330 (1939); Wellmore, U. S. iatent 2,184,705 (1939); Klemm and'Voss, Zeit. anorg. allgem. Chemie 251, 233 (1943); Gross, Mining Magazine 81, #2,126 (1929), German Patent 830,113 (1949); Weiss, Erzmetall 8, 214 (1950); Ardel Nerke, Swiss Patent 255,157 (1946) and British Patent 631,585 (1947); Aluminum Industrie, Swiss Patent 261,162 (1947) and German Patent 812,118 1950) Vereingten Aluminumwerke, German Patents 816,017, 843,598 and 846,016; Gross, Campbell, Kent and Levi, Discussions Faraday 1948, #4, 206-215; Weiss, Zeit, Erzbergbau u. Metallhuttenw. 3, 241-4 (1950).

By the application of this subhalide process to the removal of the aluminum from titanium-aluminum alloys containing 53% to 95 of titanium, it is possible to obtain a pure sponge titanium assaying less than 0.06% of nitrogen, less than 0.10% of oxygen, less than 0.25% of aluminum, less than 0.15% of chloride; with Brinnell hardness between and 250.

In effecting the process of this invention, the choice of the reagents is often of considerable importance. In the preparation of the high-titanium alloys required as intermediates in the manufacture of pure metallic titanium (the specifications for which are quite stringent), it is usually desirable to employ a pure virgin aluminum as a reagent. In the preparation of many other alloys, such as those intended for use in the manufacture of steel as a partial or a total replacement for manganese, it is entirely feasible and practical to employ the cheaper scrap or secondary aluminum, the contaminants or alloyed elements contained therein not being deleterious to the use of the ultimately obtained titanium alloy in steel manufacture.

The by-product mixture of molten salts obtained with these titanium-aluminum alloys consists of substantially eouimolecular proportions of alkali metal fluoaluminate (M AlF and aluminum fluoride. Since the starting materialthe alkali metal fluotitanateis not a common article of commerce, it is a further purpose of this invention to provide a simple process for the conversion of this by-product mixture of M AlF and All-* to the original starting material, i. e. the alkali metal fluotitanate M TiF I have found that this regeneration of the alkali metal fluotitanates may be etfected by the following sequence of steps:

Step A The slag, comprising a substantially equimolecular mixture of alkali metal fiucaluminate and aluminum fiuoride, separated from the titanium-aluminum alloy as above described is dissolved in Water and is then reacted with a quantity of a member of the group consisting of the hydroxides, carbonates and bicarbonates of the alkali metals and ammonium at least suficient to precipitate all of the aluminum ion as aluminum hydroxide. The reaction involved is:

ing point of the reaction mixture, i. e. from 70' C. to

100 C. The preferred reagent on the basis of cost and effectiveness is sodium carbonate (soda ash). If ammonia or an alkali metal hydroxide is employ'ed,.it is desirable to avoid th'e'use of a stoichiometric. excess ofthe reagent which may dissolve some of the precipitated aluminum hydroxide. If an excess of one of these reagents is employed and some aluminum hydroxide is redissolved, the treatment of the reaction mixture with a carbon dioxide-containing gas will reprecipitate the dissolved Al(OH) At the conclusion of this step, the p-recepitatedl aluminum hydroxide is filtered from the solution of alkali metal fluoride (which may contain NH F if ammonia was used as a precipitant). The filtercake of aluminum hydroxide is washed with waterandthe combined filtrate and washings are used inthe next step of the process.

The aluminum hydroxide thus recovered may be calcined by the processes wel known in the art. (e. g. at 1000l200 C.) to recover a good gradeof alpha-alumina suitable for use in theelectrolytic manufacture of aluminum metal.

Step B The combined filtrate and washings from the preceding step, comprising a solution of ammonium fluoride and/or alkali metal fluorides. is now reacted with titanic sulfate, in acidic medium, where the following reaction occurs:

The alkali metal fiuotitanate precipitates from the solution. The formation of the co-product of alkali metal sulfate or ammonium sulfate further serves to salt out or insolubilize the alkali metal fiuotitanate.

The reaction of the fluoride salt solution with the titanic sulfate may be effected at any temperature between C. and the boiling point of the reaction mixture. I prefer to effect the reaction at a temperature between 70 C. and 105 C. and thereafter to cool and (if necessary) concentrate the reaction mixture to precipitate the alkali metal fiuotitanate and separate it from the concomitant lay-product of ammonium sulfate and/or. alkali metal sulfate.

Sodium fluotitanate is soluble in water at C. to the extent of 60-70 grams per liter, potassium fluotitanate to the extent of 1113 grams per liter, and these solubilities are further diminished by the salting-out effect of the alkali metal sulfate produced as co-products of the reaction of this invention.

It is essential that the reaction of this invention be effected in an acidic medium. In an alkaline medium, alkali metal fiuotitanates will hydrolyze with the precipitation of hydrated titanium dioxide. It istherefore essential that sufficient free sulfuric acid be present in the reaction medium to yield an acidic reaction.

Titanic sulfate, or titanium disulfate-Ti(SO -can be obtained by the action of hot sulfuric acid or oleum on titanium dioxide (Von Bichowsky, U. S. Patent 1,915,- 393; Weizmann and Blumenfeld, British Patent 209,480; Titan Co., British Patent 471,397; French Patent 813,- 785; Kirkham and Spence, British Patent 263,886; Boguslavskaya and Ottamanovskaya, Journ. Gen. Chem. (USSR) 10, 673 (1940) and exists as the anhydrous salt and in the form of number of hydrates.

I find further that the basic titanium sulfates, such as titanium oxytrisulfate (Ti O(SO and titanyl sulfate (13030 or the hydrates thereof, may be used in the proces set this invention, providing that the reaction medium contains sufiicient sulfuric acid to provide a total of at least two sulfate ions for each titanium ion in the reaction mixture and in. addition to render the mixture.

acidic in reaction, e. g.

These basic titanium sulfates may be prepared by the hydrolysis of titanic sulfate or bythe. controlled. reaction of titanium dioxide with sulfuric acid (Chem. Zentralblatt 192411, 2289; 1927-1, 2234, 1930i, 1.672;.Rosenheim and Schutte,.Zeitschr. anorg. Chemie 26,, 239,50 (1901); German Patent 123,860;BritishPatenh 290,491; U. S. Patent 1,980,812; U. S..Patent 1,559,12113LB fitiSh Patent 364,613; German. Patent. 599,502).

1 also find that a mixture of titanium dioxide and sulfuric acid may be used in the processv of. this invention, providing that at leasttwo. moles.- of H are used per mole of TiO and sufiicient sulfuric acid'. in excess' is employed to give an acidic reaction in the me.- dium.

Thus, a solution of ammonium and/or alkali metal fluorides may be digested with TiO and H 50 in an acidic medium, preferably at 70 C. to C., to give the corresponding alkali metal fiuotitanate, according. to the reaction, e. g.:

The titanium dioxide used in this modification maybe in the form of anatase, brookite, rutile', as amorphous metallurgical grade titanium dioxide, as a. concentrate derived by chemical beneficiation (.e; g; the high titania slag derived in the Sorel, Quebec, operation of' the Quebec Iron & Titanium Corporation as a co-product in'the electrothermal smelting of ilmenite) or as; the low iron titania concentrate obtained by the chemical process: described inmy co-per1ding application Serial No.v 358,161, filed May 28, 1953. An excellent and highly reactive form of titanium dioxide for use in this: modification of the process is the hydrated titanium: dioxide (titanic; acid or metatitanic acid) derived by the hydrolysis of titanium salts (such as Ti (SO or TiCl andznow manufactured in large tonnages as intermediates in the: preparation of pigment grade titaminum dioxide;

A preferred embodiment of the process of this inven.- tion involves the use of the crude technicall solution of titanic sulfate, which may contain considerable amounts of iron sulfates, obtained in the Washburn process for the manufacture of titanium. dioxide (U. S. Patent 1,889,027 (1933); British Patent 288,569 (1927);. French Patent 652,357 (1928); Canadian Patent 299,992 (1930). Ilrnenite (or a high-titania iron-oxide con:- taining ore or slag) is ground, digested with concentrated sulfuric acid, diluted with water, treated with a: reducing agent to convert ferric sulfate to the ferrous state clarified by the addition of antimony sulfide and a proteinaceous material which serve to carry down all suspended matter, cooled to separate and crystallize out a large portion of the ferrous sulfate in the solution, and thereafter filtered to separate the filtrate of titanic sulfate.

The solution at this stage will contain 420 to 450 gms.- Ti(SO 80 to 85 gms. FeSO and 65 to 70 gms. free H SO per liter. This solution may be further evapm rated in lead-lined evaporators to approximately 600 gms. Ti(SO gms. FeSO and 70 gms. free H SO per liter. Either of these technicalsolutions may be usedias a source of titanic sulfate in the process of this invention. As long as the reaction mixture is maintainedin the acidic state, the iron salts show no tendency toprecipitate, and the alkali metal fluotitanates are precipitated in a state of high purity. The ferrous sulfate remains dissolved in the filtrate and in no ways interferes with the recovery of the alkali metal fluotitanate.

Thus, it becomes feasible by this process to make alkali metal fluotitanates employing the cheapest technical form of titanium salt solution now industrially available, i. e. the crude FeSO -containing titanic sulfate solution of the Washburn process. This solution is often concentrated further, cooled and filtered to remove more E280 and finally allowed to form a solid cake containing the equivalent of about 20% TiO 50% H 80 and 30% water and ferrous sulfate, proportions corresponding approximately to Ti(SO .9H O in composition. This cake is also ideally suitable for use in the process of this invention. All present processes for the manufacture of titanium metal require the use of a highly purified titanium salt as a starting material, as does the sodium reduction of alkali metal fiuotitanate process described and claimed in my co-pending application Serial No. 438,873, filed June 23, 1954. It is therefore highly important to stress that such high purity alkali metal fluotitanates may be obtained 'by the process of this invention although we use as raw material the crude FesO -containing titanic sulfate solution obtained in the widely practiced Washburn process.

The following examples are given to define and to illustrate the present invention but in no way to limit it to reagents, proportions or conditions described therein. Obvious modifications will occur to any person skilled in the art.

Example I A graphite-lined crucible is charged with 172 kgs. of molten aluminum metal and 623 kgs. of anhydrous sodium fiuotitanate is added in small portions. The reaction mixture is placed in an induction furnace and is heated with agitation, until the reaction is complete and the reaction mixture has attained a temperature of about 1400 C. The molten reaction mixture is maintained near this temperature for about 15 minutes and is then cooled and allowed to solidify. The solidified mass is broken mechanically into lumps and is then leached with 17,000 liters of hot water. The hot solution is filtered from the insoluble alloy, which is washed free of soluble matter with a further 2000 liters of hot water. The filtrate and washing are combined. The alloy thus recovered is dried. There is thus obtained 200 kgs. of an alloy containing 70% of titanium and 30% of aluminum.

To the hot filtrate obtained above, there is now added 636 kgs. of soda ash and the reaction mixture is heated and agitated at 90-100 C. until no further carbon dia oxide is evolved and the precipitation of aluminum hydroxide is complete. The precipitate is filtered off and is washed with small amounts of boiling water until free of soluble matter. The filtrate and washings are combined. The filtercake of aluminum hydroxide, on being calcined at l0001200 C. by the well known techniques of the prior art, is converted to 200 kgs. of a good grade of alpha-alumina.

The combined filtrate and washings (containing NaF) are now treated with a slurry of titanic sulfate obtained by the digestion of 240 kgs. of titanium dioxide in 675 kgs. of 66 B. sulfuric acid. The reaction mixture is heated with agitation for 30 minutes at 90100 C., and is then concentrated to a volume of 4000 liters, preferably under reduced pressure. (In the cyclic operation of this process, it is desirable to add 38 kgs. of sodium fluoride (5% per cycle) to the filtrate and washings prior to reaction with titanic sulfate to compensate for mechanical losses). The reaction mixture is now cooled, and the precipitated sodium fiuotitanate is'filtered ofl, and dried by a short heating (e. g. in a rotary kiln at 150-200 C.). There is thus recovered (in the cyclic operation of this process) the 623 kgs. of anhydrous sodium fluotitanate required in the first step of the process.

On concentrating and crystallizing the filtrate from the Na TiF precipitate, preferably at a temperature above 35 C., there is recovered a salable by-product of 840 kgs. of saltcake.

Example II A crucible is charged with 252 kgs. of molten aluminum metal and 721 kgs. of anhydrous potassium fiuotitanate is added in small portions. The reaction mixture is placed in an induction furnace and is heated, with agitation, until the reaction is complete and the reaction mixture has attained a temperature of about 1300" C. The molten reaction mixture is maintained near this temperature for about 20 minutes and is then cooled and allowed to solidify. The solidified mass is broken mechanically into lumps and is then leached with 15,000 liters of hot water. The hot solution is filtered from the insoluble alloy, which is then washed free of soluble matter with a further 3,000 liters of hot water. The filtrate and washings are combined. The alloy thus recovered is dried. There is thus obtained 290 kgs. of an alloy containing 50% titanium and 50% aluminum.

To the hot filtrate obtained above, there is now added with good agitation 730 kgs. of 28% aqua ammonia and the reaction mixture is heated and agitated at 90- 100 C., While passing through a stream of a carbon dioxide-containing gas (e. g. filtered flue gas) until the precipitation of aluminum hydroxide is complete. The precipitate is filtered off and is washed with small amounts of boiling water until free of soluble matter. The filtrate and washings are combined. The filtercake of aluminum hydroxide, on being calcined at 1000"- 1200" C., is converted to 190 kgs. of a good grade of alpha-alumina.

The combined filtrate and washings (containing KF and NH F) are now heated with a quantity of the titanic sulfate filtercake from the Washburn process (containing about 20% TiO 50% H 30% water and minor amounts of FeSO containing the equivalent of 240 kgs. of titanium dioxide. The reaction mixture is heated with agitation for 30 minutes at 100 C., and is then concentrated to a volume of 4500 liters, preferably under reduced pressure. (In the cyclic operation of this process, it is desirable to add 85 kgs. of KF.2H O (5% per cycle) to the filtrate and washings prior to reaction with titanic sulfate to compensate for mechanical losses.) The reaction mixture is now cooled, and the precipitated potassium fiuotitanate hydrate is filtered off and dehydrated by calcining at 200-300 C. in a rotary kiln. There is thus recovered (in the cyclic operation of this process) the 721 kgs. of anhydrous potassium fluotitanate required in the first step of the process.

On neutralizing the filtrate with aqua ammonia, concentrating and crystallizing, there may be recovered a salable by-product of 795 kgs. of ammonium sulfate.

Having described my invention, what I claim and desire to protect by Letters Patent is:

l. A cyclic process for the manufacture of titaniumaluminum alloys containing 0.1% to of titanium, and the regeneration of the intermediates of said process which comprises in combination the steps of initially reacting an alkali metal fluotitanate with metallic aluminum in stoichiometric excess at temperatures between 650 C. and 1800 C. to obtain the said titanium-aluminum alloy and a by-product salt mixture of alkali metal fiuoaluminate and aluminum fluoride, thereafter separating said alloy from said salt mixture, reacting said salt mixture of alkali metal fluoaluminate and aluminum fluoride, in an aqueous medium, with at lest one member of the group consisting of ammonium hydroxides, ammonium carbonates, ammonium bicarbonates, alkali metal hydroxides, alkali metal carbonates, and alkali metal bicarbonates in quantity sufiicient to precipitate all of the aluminum ions in the salt mixture as aluminum hydroxide, separating said precipitate of aluminum hydroxide from the resulting solution containing at least one member of the group consisting of ammonium fluoride and alkali metal fluorides, reacting said solution with a titanium containing product comprising at least one member of the group consisting of titanic sulfate, basic titanium sulfate, and titanium dioxide, the reaction mixture containing at least two equivalents of sulfate ion for each equivalent of titanium ion, separating the resultant alkali metal fluotitanate from the reaction mixture, and recycling said separated alkali metal fluotitanate to the above said initial reaction of alkali metal fluotitanate and metallic aluminum.

2. The process of claim 1 where from 38.5 grams to 47.9 kilograms of metallic aluminum is reacted with each gram-mole of alkali metal fluotitanate.

3. The process of claim 1 Where the alkali metal fluotitanate is sodium fluotitanate.

4. The process of claim 1 where the alkali metal fluotitanate is potassium fluotitanate.

5. The process of claim 1 where the reaction mixture of the alkali metal fluotitanate and metallic aluminum is brought to a terminal temperature within the range of 900 C. to 1550 C.

6. The process of claim 1 wherein the titanium-containing product employed is titanic sulfate of composition Ti(SO 7. The process of claim 1 wherein the titanium-containing product employed is titanium dioxide in the presence of at least suflicient sulfuric acid to provide an acidic reaction medium containing at least two moles of sulfate ion per mole of titanium ion.

8. The process of claim 1 wherein the titanium-containing product employed is titanic sulfate containing iron sulfate and free sulfuric acid.

9. The process of claim 1 wherein the titanium-containing product employed is in the form of a solution containing 400 to 700 grams per liter of Ti(SO together with iron sulfate and free sulfuric acid.

10. The process of claim 1 wherein the titanium-containing product employed is a hydrated titanium dioxide obtained by the hydrolysis and filtration of a member of the group consisting of titanic sulfate and titanium tetrachloride.

11. The process wherein the titanium-aluminum alloys prepared as described in claim 1 containing more than 53% of titanium are comminuted and leached with an alkali metal hydroxide solution to dissolve the aluminum contained therein and separate the titanium metal content thereof.

12. The process wherein the titanium-aluminum alloys prepared as described in claim 1 containing more'than 53% of titanium are distilled to volatilize the aluminum contained therein and separate the titanium metal content thereof.

13. The process wherein the titanium-aluminum alloys prepared'as described in claim 1 containing more than 53% of titanium are distilled in the presence of an aluminum trihalide to volatilize the aluminum contained therein as the aluminum monohalide and separate the titanium metal content thereof.

14. The process wherein the titanium-aluminum alloys prepared as described in claim 1 containing more than 53% of titanium are distilled in the presence of aluminum trichloride to volatilize the aluminuin contained therein as aluminum monochloride and separate the titanium metal content thereof.

Annalen der Chemie, vol. 357, pp. -144 (1907). Article by Manchot et al.

Journal of Metals, June 1952, pp. 610-164. Pub. by the A. I. M. E., N. Y., N. Y.

U. S. DEPARTMENT OF COMMERCE PATENT-OFFICE CERTIFICATE or CORRECTION Patent No 3 ,4 Jonas Kamlet June 3,, 1.958

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and. that the said Let uers Patent should read as corrected below.

Column 2, line 26,. for WO -lim (h read' 9G0-ll00*6, column 3, line 16, for "Patents 2,252,241" read Patenjas 2,252,423. .e-g line 18, for "16," read 19, column. 4, line 17, for (3929)" read (EWB) Signed and sealed this 5th day of August 195$.

(SEAL) Attest:

KARL AXLINE mean 0. wxrson Attesting Officer Cmmiseiomr of Patents U S DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF ECTIGN Patent N- 37,4 J0me Kamlet June 3,. l958 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let oers Patent should read as corrected below.

Column 2, line 26,] for "go -4.1m? m zeaa 9e0-11o0 m celumn 3, line 16,. for "Patents 2,252,241" read Patents 2,252,423. line 18, for "16," read 19,-. column 4, line 17, for (1929)" read lee (1949) t Signed and sealed this 5th day e1 August 1958::

(SEAL) Attest:

KARL H, AXLINE RQBER'E' C. EATSGN Attesting Officer 7 winner ef Patfiilit

Claims

1. A CYCLIC PROCESS FOR THE MANUFACTURE OF TITANIUMALUMINUM ALLOYS CONTAINING 0.1% TO 95% OF TITANIUM, AND THE REGENERATION OF THE INTERMEDIATES OF SAID PROCESS WHICH COMPRISES IN COMBINATION THE STEPS OF INITIALLY REACTING AN ALKALI METAL FLUOTITANATE WITH METALLIC ALUMINUM IN STOICHIOMETRIC EXCESS AT TEMPERATURES BETWEEN 660*C. AND 1800*C. TO OBTAIN THE SAID TITANIUM-ALUMINUM ALLOY AND A BY-PRODUCT SALT MIXTURE OF ALKALI METAL FLUOALUMINATE AND ALUMINUM FLOURIDE, THEREAFTER SEPARATING SAID ALLOY FROM SAID SALT MIXTURE, REACTING SAID SALT MIXTURE OF ALKALI METAL FLUOALUMINATE AND ALUMINUM FLUORIDE, IN AN AQUEOUS MEDIUM, WITH AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF AMMONIUM HYDROXIDES, AMMONIUM CARBONATES, AMMONIUM BICARBONATES, ALKALI METAL HYDROXIDES, ALKALI METAL CARBONATES, AND ALKALI METAL BICARBONATES IN QUANTITY SUFFICIENT TO PRECIPITATE ALL OF THE ALUMINUM IONS IN THE SALT MIXTURE AS ALUMINUM HYDROXIDE, SEPARATING SAID PRECIPITATE OF ALUMINUM HYDROXIDE FROM THE RESULTING SOLUTION CONTAINING AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF AMMONIUM FLUORIDE AND ALKALI METAL FLUORIDES, REACTING SAID SOLUTION WITH A TITANIUM CONTAINING PRODUCT COMPRISING AT LEAST ONE MEMBER OF THE GROUP CONSISTING OF TITANIC SULFATE, BASIS TITANIUM SULFATE, AND TITANIUM DIOXIDE, THE REACTION MIXTURE CONTAINING AT LEAST TWO EQUIVALENTS OF SULFATE ION FOR EACH EQUIVALENT OF TITANIUM ION, SEPARATING THE RESULTANT ALKALI METAL FLUOTITANATE FROM THE REACTION MIXTURE, AND RECYCLING SAID SEPARATED ALKALI METAL FLUOTITANATE TO THE ABOVE SAID INITIAL REACTION OF ALKALI METAL FLUOTITANATE AND METALLIC ALUMINUM.