US2840465A

US2840465A - Method of producing titanium

Info

Publication number: US2840465A
Application number: US315604A
Authority: US
Inventors: Douglas S Chisholm; Don F Hall
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1952-10-20
Filing date: 1952-10-20
Publication date: 1958-06-24
Anticipated expiration: 1975-06-24

Description

June 24, 1958 D. s. cHlsHoLM Erm. 2,840,455f

METHOD 0F PRODUCING TITANIUM Filed ocu 2o. 1952 I5v Sheets-Sheet 1 June 24, 1958 D. s. cHlsHoLM :TAL l 2,840,465A

METHOD oF PRoDUcING TITANIUM v l Filed oct. 2o. 1952 f 3 sheets-sheet 2 Il: Mg loar/l'c/es i i g I I gfelf Tis/conge O n Il INVENTORS.

www@

A TTORNE YS June 24, 1958 n. s. cHlsHoLM Erm. 2,840,465

METHOD 0F PRODUCING TITANIUM Filed oct. 2o, 1952 s sheetsheet :s

Aff in J 66 INVENToRs. @Dug/0s CM'S/m/n BY om F. f-/a// Arrow/Ys Mari-ion on rnonucnso TITANIUM 1 Douglas S. Chisholm and Don F. Hall, Midland, Mich.,V

assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Application Uctober 20, 1952, Serial No. 315,604 s calms. (ci. lsaaa arent method of and apparatus for the production of the metals, -titanium and zirconium, by reacting a volatile halide thereof, especially the tetrachloride, with magnesium.

Heretofore in the reduction of titanium tetrachloride,

for example, in accordance with the reaction: ZMg-l- TiCl4=Ti-l- 2MgCl2, the magnesium used has been in the form of a pool of themolten metal in a retaining vessel with the upper surface ofthe poolrexposed to the vapor of the titanium tetrachloride. In the `ensuing reaction, there is formed a sponge-like mass of metallic titanium in situ, together with molten magnesium chloride as a by-product. A number of disadvantages nure to this practice which limits its usefulness. VAmong these disadvantages are that some of the magnesium becomes occlucled in the titanium sponge yand is thus prevented from being used, thereby lowering the eiliciency ofthe reduction operation. The sponge so-formed in situ sticks to the Walls of and tends to form a bridge in the retaining vessel and is diicult to remove, in spite of the fact that the magnesium metal during-the reduction more or less floats upon molten magnesium chloride. Another disadvantage is that the reaction tends to'getfout of control allowing the magnesium to overheat and vaporize, thereby producing an undesirable flame-like ret action in which the magnesium `burns as avapor inthe titanium tetrachloride vapor forming dust-like particles of metallic titanium instead of sponge. Thedust-like' particles of titanium thus produced are exceedingly .difcult, if not impossible, to recover as massive titanium metal. Another disadvantage is that the titanium sponge is bulky and very reactive vwhile hot necessitating essentially batchwise operation to permit cooling for the removal of the Vsponge from the-retaining vessel and replacement of the supply of magnesium metal for the reduction. Similar diiiculties arise in the reduction of zirconium tetrachloride with magnesium. insofar as we are aware, there is neither a method nor an apparatus: extant for the production Vof either titanium or zirconium metal by the reduction of the tetrachloride of these metals with magnesium which are not hampered in one way or another by the foregoing diiiiculties. Accordingly, it is the principal object of the invention to provide an improved method Vof and apparatus'for carrying out the reduction of the aforesaid halides YWithout the diticulties attendant upon; the use ofthe conventional methods and means.- Otherobjects andLadvantages will become apparent as the `description of the invention proceeds.

Pursuant to the present invention,'it has 'been dis-` covered in reacting titanium tetrachloride v'apor,Y for with apparatus for practicing the same.

hice

Patented June 24, 1958 vapor, ignition and smoldering ofthe powder` occurs inv from the zone of formation as the particles fare brought to ignition temperature. At the same time by abstracting sufficient of the. resulting heat of the reducing lreaetion'frorn the smolderingmass of magnesium'particles through the supporting surface, they are prevented from bursting into llame and the reacting particles are maintained in a smoldering do lnot run together, instead they remain `as a porous mass, thereby providing interstices throughout the pile.

The titanium tetrachloride vapor is thereby .enabled to,

permeate the-pile and use all the magnesium particles, and much of the molten magnesium chloride is able.' to more or less drain Vaway from the smoldering portion of the train as the reaction proceeds. As a result, there is yformed inrsitu a Vtitanium sponge occupying a space about twice that ofthe consumed train orl piley of mag-v nesium particles without producing titanium metal dust,

the sponge being substantially free from unreactedmagnesium metal. Moreover, the sponge so-'producedimay be readily removed from the Isupporting surface VVbeyond the smoldering zone of the train without'interrupting the reductionv operation. The method is preferably carried out in continuous manner by continuously lengthen-l ing the train or pile 'of magnesium particles at oney end ahead of the smoldering portion,l at arate sufficientl to keep Va supply of magnesium particles aheadof Vthe smoldering ones,-while removing` the producedsponge from the other end behind the smoldering portion. Analogous results are obtained on applying the same methodY with zirconium tetrachloride vapor. The invention then consists of the. improved methodand apparatus herein fully described and particularly pointed` out in the claims, theannexed drawing and following description setting forth various modes of practicing the invention. K Y 'j H In the said annexed drawing, Fig. 1 is a'sc'hematic diagram illustrating the method of the invention together.l

Fig. 2 is a side elevation largely paratus according to the invention.

Fig. 3 Ais a horizontal section line 3h3 of Fig. 2.

in section. of, an'. ap-

On referring to Fig. l, it will be apparent that this is ydiagrammatic representation of the method generally`out` lined above and the ligure illustrates the-principle of carrying out the reaction in accordance with the inven-l particle feeder 4, 'above the supporting surface for del Y* positing thereupon the. magnesium particles, ,the .rate of example with magnesium, that by particulating the magtion, as applied to the production of titanium, for example,

by a controlled smolden'ng of a trainV orpile of particles of magnesium in an atmosphere oftitanium'tetrachloride vapor. In this figure is shown, a supporting surface" 1, on which the reaction of the magnesium particles with the halide vapor is to take place; The supporting surface `is provided with ltemperature control means comprisingsetv of pipes 2, embeddedy in the supporting' surface,

through Vwhich air at a suitable temperatureimayibe passed. The supporting surface is placed within'an enve lope, not shown, for retaining an ambient atmosphere=3 of titanium tetrachloride vapor with which the magnesium particles( Aare to react. Means are providedsuch'as-'the deposition beingsubject to control, as by means of lt-lle valveS. A Withthis `apparatus, a train of particulated magnesium is show-n as havingbeen depositedfupon'thesupprtng state until consumed. Theparv ticles ,ofmagnesiurn Vthus treated reach a temperature` t at .least above that of the molten magnesium chloride formed in the reactionas a by-product,.but the particles f' of the apparatus on the:

3 surface by a relative sideways movement of the feeder outlet 6 with respect to the supporting surface in the direction of left to right. The train of particles Yso-formed passes 4through a number of changes occurring in sequence' in more or less distinct Zones moving'along the train in the ensuing reaction which consumes the train as it forms leaying Vtitanium sponge in situ.

As .to these changes, the train begins, as aforesaid, with the deposition of the particles on the supporting surface. This. takes placeu at the pile-.or train-forming zone 7 below the feed-pipe 6 .from which the particles fall. The particles at this stagesare relatively cold; that is the temperature is belowV that at which they will spontaneously ignite in the tetrachloride atmosphere. The pile-forming zone is followedby a preheating zone 8 in which the particles a're subjected Ato heating bothY by Contact with the-supporting surface and by contact with adjacentparticles already ignited and burning in the following pzone.

The heating which occurs in the preheating zone raises the temperature of vthe particles progressively alongVv the preheating zone to a temperature atwhich ignition or burning ofthe magnesium particles in the halide'ratrnosphere begins. Thus, -a-n ignition zone is `established adjacent to the hotter end of the preheating zone, as indicated by numeral 8, the hotter end being remote from the zone of formation. The ignition Zone on the forward end is sharply distinct from the preheating vzone while the rear of the ignition zone merges into a smoldering zone designated by numeral 10 where the particles become hotteras the reaction proceeds. In the front of the smold-V ering zone, the ignited particles communicate some of their heat to adjacent unignite-:l particles and as already mentioned thereby maintain ignition in the ignition zone. Burning ofthe particles continues in the smoldering Zone until all magnesium particles are consumed forming titanium sponge in situ as a loaf or cake and molten magnesium chloride.

In the smoldering zone, more than enough heat is liberated -to maintain the reaction at a smoldering pace, and,accordingly, in this zone, the smoldering particles are subjected .to a heat exchange in which a sucient amount'ofthe heat of the reaction is abstracted from the" pile 4as through Athe supporting surface, by means of a cooling air blast through pipes 2, to prevent the smoldering particles from overheating and bursting into flame. The amount of heat exchange required to maintain the burningof the ignited particles at a smoldering pace is readily ascertained by trial as by watching Vthe smoldering zone and suppressing the reaction by cooling the supporting surface enough to prevent flame formation. been found by maintaining the supporting surface under the smoldering zone at a temperature sufficient to cause ignition of the particles in the halide atmosphere but not in excess of about 900 to 950 C. the reaction rate can be maintained at a smoldering pace. A preferable temperature for the supporting surface is above that suf# cient to maintain the by-product magnesium chloride in the molten state (e. g. about 708 C.) but less than about 850 Temperatures lower than the melting point of magnesium chloride can be used (e. g. 600 C.) if the solid .magnesium chloride which then tends to collect upon the supporting surface can be removed.

Bothduring and Ifor some time after the smoldering action,:a substantial proportion of the magnesium chloride drains out of the sponge. The Zone of Ysuch drainage ofA the trainis indicated at 11 and partially overlaps the smolderingY zone 10. The resulting partially drained sponge 12 ileftat thev end of the smolderingzone, `after all the magnesium has been consumed in reducing tetrachlorideyapor, may be removed from the supporting surface, asby a cooled scraper 13, in the form of chunks of sponge 14.

Wby-pro'duct magnesium chloride which in part drains optof the sponge andloff the` supporting. surface L.

It has.

. this'lrnode of operation, theV supporting surface for theA as shown, may be collected in any convenient manner below the supporting surface, and, if desired, reworked for its magnesium content in conventional manner for reuse in the method.

The foregoing method may be conducted advantageously upon a moving hearth or supporting sunface which moves sideways away from the train-forming zone beneath the magnesium particle feeder at a rate which is equal, on the average, to the rate at which the zone of ignition moves toward the forming end of the train. In this way, the various zones above described in connection with Fig. l are obtained which remain in the same relative positions and the process is thereby made continuous. In such mode of operation, the path of the train of magnesium. particles is preferably madein the form of a segment of a circle as by the use of a revolving supporting surface arranged beneath a magnesium particle feeder which remains stationary with respect to `the supporting surface on which th'eefeeder deposits the particles as the surface moves. Y l

This mode of operationand `an apparatus therefor is illustrated in Figs?. Vand 3 which will now be described. In

magnesium particles may be in the form of a hollow air cooled disc 15, for example, secured to the lower end ofV thehollow drive shaft 16, the discV being within the reaction vessel-'17 which holds the atmosphere containing the titaniumtetrachloride vapor to -be reduced. The reaction vessel 17 is supported in a furnace setting 18'by means ofV which the disc 15'may be heated to a temperature suicient at least to initiate the reaction of the magnesium with the halide vapor to begreduced and preferably to maintain the Aby-product magnesium chloride in the molten state. The reaction vessel 17 is provided with a gas tight cover 19 for retaining withinV the vessel the atmosphere containing `the halide-vapor with :which the magnesium is to react. The cover is provided with an opening 20 through which passes the aforesaid shaft 16. The stufng box 21, secured to thecover around the'opening 20, provides a gas tight seal for the shaft 16.V The shaft is supported near its upper end by means ofthe thrust-bearing 22 which rests on supportf23. Drive pulley 24 is secured to the upper end of theshaft and is driven by means of motor 25 through the reductionfgearingV `26, pulley 27, and belt 28.

Throughthe hollow shaft 15 Vextends the pipe 29 for.

return air from the hollowdisc escapes up the annular' space 33 between the outside of pipe 29 and the inside of the hollow shaft 16.

The particulated magnesium to be deposited upon the disc 1S is introduced into the' vessel from a supply hopper 34 through a screw conveyor `35 and feed pipe 36, the outlet 37 of-which is arranged directly over the disc 15 al short distance inward `of its periphery. Receptacle 33 ho'ldsa supply` of the halide .(e. g. liquid titanium tetrachloride) 'which' is vaporized in the vessel 17 and reduced to metal on the disc' V15.l Thereceptacle 38 is connected to thefinside of the reaction vessel through the cover by pipe 39 having a valve 40 for controlling the rate of introduction of the'halide into the vessel. A` manometer 41 provides 'a means for ascertaining the difference in the pressure between vthe atmosphere outside the vessel and that on the inside. "Extending through the cover 19 at anoblique angle is a viewingldevice consisting of a tube 42 with a transparent eye-piece 43 through which'may be seen the upper sidelof the hollow disc 15. r1he `reaction vessel 17'is provided .Witha hopper bottom 44cmthe `inside'of which. is arranged'theinclined `screw conveyor 45. As shown, the screw conveyor comprises the single plate helixr46 wound on the shaft'47, the helix having small openings 1S.-'tlzi'enthrcugh tofallowliquidto ldraiuso that the conveyor will not function to elevate liquid. The lower end of the shaft 47 is journaled in the bearing 49 mounted in the vessel. The upper end of the conveyor extends into an inclined tube 50 which passes through the vessel to the outside. Thelower end 51 of the inclined tube extends into the vessel for a sufficient distance to form a seal with the pool 52 of molten magnesium chloride which is maintained in the vessel during operation. The vessel is provided with an outlet 53 below the surface 54 of the pool of molten magnesium chloride, the outlet being provided with a trap 55 lby means of which the level of the surface 54 is maintained above the lower end 51 of the inclined pipe. The trap has an outlet 56 outside the furnace setting through which molten magnesium chloride is withdrawn from the pool. The upper end of the inclined pipe is provided with a ange 57 to which is secured the cover plate 58. The cover plate is provided with an opening 59 which forms a bearing for the upper end of the screw conveyor shaft 47. Near the upper end of the inclined tube 50 is a downwardly extending T, 60, having a flanged opening 61 to which Vmay be detachably secured the vessel 62 by means of clamps 63.

An air cooled scraper indicated generally by numeral 64 (Fig. 3) is provided over the disc 15 for removing the metal sponge formed thereon. As shown, this device comprises a hollow scraper head 65 carried on one end of a hollow shaft 66 by means of which the head 65 is moved back and forth across the upper surface of the disc 15 as indicated in dotted outline. The shaft 66 extends through a tube 67 one end of which is joined to the side of the vessel 17, around an opening 68 therein, and the other extends through the side of the furnace setting 18.Y A stung box 69.is provided on the outer end of the tube 67 for making a seal around the shaft 66, the seal permitting longitudinal reciprocatory movement Without leakage of air into the vessel 17. A bearing in the form of an annular ring 70, together with the stuling `box 69,maintains the shaft 66 aligned in the bore of tube 67. Reciprocatory motion of the shaft 66 is provided through the link 71 connecting the shaft with the crank pin 72 on gear wheel 73 which is rotated by pinion 74 on motor 75.

Cooling of the scraper head 65 is elected by means of the pipe 76 which extends through shaft 66 to near the inside of the working face 77 of the scraper head. The pipe 76 is connected by a iiexible hose 78 `toa source of air (not shown). The air delivered by the pipe 76 to the scraper head exhausts through the annular space 79 between the inside of the shaft 66 and the outside of the pipe 76.

ln operation, as with titanium tetrachloride for example,

number of more orls distinct zones of action which characterize the method. 4With the apparatus of Figs; 2 and 3, a series 'of zones similar to that of Fig. 1 is formed butin a train having the form of a segment of a circle instead of a straight line since the train is deposited upon a revolving surface from a fixed feeding point. Referring to Fig. 3 in particular, these zones are indicated as follows: pile or train-forming zone, 81; Vpreheating zone, 82; ignition zone, 83; smoldering zione, 84; drainage zone, 85; sponge removal zone, 86. The depth of the pile or train is controlled by the rate of actuation of the screw conveyor 35 as well as by the rate of turning of the disc l15.

The depth of the train which gives satisfactory burning or smoldering does not appear to be sharply critical. If the train is relatively thin propagation of the smoldering zone yinto the preheating zone is more or less erratic and discontinuity of operation may result.` .If the train depth is excessive, there is a tendency for some magnesium particles to be left unburned. Proper depths for the train are readily ascertained by trial during operation and are 'evidenced by continuity of the burning orV reaction of the magnesium in the tetrachloride vapor without llame, and

the absence of unconsumed magnesium particles in the resulting sponge. Successful operation' has been had, for

' example, at depths ranging from 1A: inch to as much as 11/2 inches. Y

In any event, the rate of turning of the disc mustnot exceed the rateV at which the ignition zone 82 progresses along the train which becomes heated, then ignites, and Smolders in zones progressing along the trainas indicated in the drawing. It will be understood that the'lengths of 'the zones is not critical and varies with operating conditions, and sufficient time should be allowed in generating the train for the smoldering to be completed before removing the sponge from the disc.` By directing the viewing tube at the point in thetrain where the ignition zone merges into the preheating zone, the ratev of turning of the disc can be adjusted readily to that which will'maintain the ignition zone close to the pileor train-forming the reaction vessel is maintained at a temperature sucient to maintain the pool 52 of magnesium chloride in Ythe molten state, the molten magnesium chloride of the pool forming a seal against the escape of tetrachloride vapor from the reaction vessel through the outlet 53 and the tube 50. The tetrachloride to be reduced is introduced into the reaction vessel at a rate preferably suti'cient to maintain therein a slightly greater pressure of the halide vapor than the atmospheric pressure outside the vessel. In starting up, the heating of the vessel by the furnace setting 18 in time heats the hollow disc 15 until it is hot enough to initiate the reducing reaction between particulated magnesium and the tetrachloride vapor. When the disc is thus made sufficiently hot feeding thereon of the train of particulated magnesium is begun. This is accomplished by revolving the disc 15 slowly by starting motor 25 and operating the screw conveyor 35 so as to convey magnesium particles from the supply hopper 34 to the upper surface of the disc 15. While magnesium particles are allowed to fall from the outlet 37 ontothe slowly moving disc 15, a train of particles is thereby laid down as indicated at 80. As already explained in connection with Fig. l, that by the formation of the train of magnesium particles upon a heated supporting surface in the tetrachloride atmosphere, there is established in theV train a tion is continuous, is for example from about 0.1 to 0.5

foot per minute for particles passing through a No. V20 sieve with 95 percent retention on a No. 200 sieve and laid in a train containingper lineal foot from` lto 36 grams of magnesium. For example,.a disc, 20 inches kin diameter on which is formed a pile of magnesium particles Y' in the form of a segment of aY circle about 2 incheswide and about 21/2V inches. from the periphery of the disc, may be turned at the rate of about 0.2 to 0.6 R. P. M. depending upon the rate of smoldering. The smoldering zone thus moves along the sequential train on the disc inV a direction opposite to that in which the disc rotates, and, by a suitable regulation of the speed of rotation ofthe disc, is maintained constantly at about the same position with respect to the outlet 37 during operation. Thevbyproduct magnesium chloride in part drains out ofthe resulting sponge in the drainage zone 85 and drips off the disc into the pool 52 while the disc turns.

y The partially drained sponge left after the smoldering has ceased is periodically pushed or scraped ol the 'disc in chunks by the. cooled scraper head 65, which is caused to reciprocate back and forth across theV path of `the train by actuating motor 75, the head being cooled suliiciently to prevent the sponge from sticking to it` by directing air into the head through theV hose 78 Withl this scraper device, the `sponge is somewhat compacted on be- Iing subjected to the pressure of the scraper head as it pushes against the sponge in scraping it off the disc, as the sponge is at a temperature generally above 708 C., the melting point of magnesium chloride, and somewhat plastic at this stage. The resulting more or less compacted hot chunks or pieces of sponge fall into the pool 52 of molten magnesium chloride and on actuating the screw conveyor 4S are carried out of the pool through a seal `of magnesium chloride in tube 50 into the vessel 62, out `of contact withair. After sufficiently cooling the chunks in the vessel, it may be removed from the conveyor and emptied. Much of the by-product megnesium chloride overflows through the trap 55 and is discharged at 56, the balance of the magnesium chloride is contained in the Vvpores of the sponge.

The titanium sponge thus produced is readily worked into massive metal by conventional methods to yield a high quality metal.

In providing the particulated magnesium for use in the method, it is desirable to eliminate particles which are dust-like from the feed, although a small amount, such as up toV 5 percent by weight, of dust-like particles can be tolerated. In general, it is desirable to use particles larger than those passing through a No. 200 sieve (of the standard screen scale) to avoid loss by dusting. A rela tively short drop, such as 6 inches, from the outlet 37 of the feed pipe to the supporting surface is desirable as the short drop tends to lessen dusting and also undesirable bouncing and rolling of the particles on reaching the supporting surface. Large particles arerobjectionable be cause on melting they coalesce into still larger molten masses which tend to flow off the reaction supporting surface without forming the sequence of zones described. Particles between these extremes may be used and may be produced in various known ways, such as by grinding, chipping, milling, and atomizing. Particles which are more or less equiaxed, such as those made by the usual atomizing methods, produce the best results. Equiaxed particles as large as those passing through a No. l() sieve may be used, although somewhat finer particles are preferable, such as Athose passing through a No. sieve with at least 95 percent retention on a No. ZOO-sieve.

The particles of magnesium as introduced into the tetrachloride atrnosphere, on being caught upon the supporting surface for reaction, are relatively cold so that reaction does not commence to a significant extent until the particles are actually in the form of a pile or train upon the supporting surface. This mode of operation overcomes the clogging at the outlet 37 which can occur when the particles vfed through it are too hot or too tineV and tend to burn las they fall through the .pipe 36. If desired, an inert gas, such as argon or helium, may be fed into the pipe 36 as though a pipe connection 64 to block the tendency for the vapor of vthe volatile halide to enter the pipe 36 from the reaction vessel 17. The dilution, if any, which may result from the presence of the inert gas in the atmosphere in the reaction vessel does not significantly alfect the reduction reaction, although provision for venting the inert gas from the reaction vessel may be required as by means of a vented condenser, not shown.

The particles of magnesium may be deposited upon the hearth or supporting surface at as rapid a rate as that at which the zone of ignition advances in the resulting train or elonfated pile. At the same time, the halide to be reduced is introduced into the reaction vessel at a rate suflicient to maintain therein a pressure of the halide vapor preferably in excess of the atmospheric pressure outside the vessel. For example, the vapor pressure in the reaction vessel of the halide to be reduced may exceed the atmospheric pressure by 1 to 2O inches of water (as in manometer 4l) but other pressures may be used.

While the invention has been exemplied with particular reference to the deposition of the train .or pile of particulatedf magnesium upon flat surfaces, it is to beunderstood that other solid supporting surfaces may be used in .8 similar manner, although notilat, such as cylindrical or conical surfaces. ln s uch instances, the cylinder or cone, for example, is arrange'dto revolve on its 'axis in such a manner that the underside of a more or less horizontal plain surface willbe tangent to the revolving surface at least at the place Where the particles are deposited. It will be found also that even though the supporting surface is made to slope away from the point of deposition of the particles so as to facilitate drainage of the by-product magnesium chloride, the tendency for the particles to roll oi i.. reduced, if not completely counteracted, during their reaction with the halide vapor, the reaction products of which give adhesion tothe particles for cach other and the supporting surface when wet with molten magnesium chloride.

Among the advantages of the invention are that the magnesium, in particulate 'form and arranged in a pile and made to smolder, becomes lcompletely consumed in the atmosphere of the halide to be reduced. There is, therefore, a maximum efciency of use of the magnesium. The metal obtained from the reduced halide vapor is substantially all in the form of easily recoverable sponge, there being substantially no produced metal in the form of dustlike particles which are diicult, if not impossible, to recover. The method is adapted to continuous operation without contamination of the metal product by the atmosphere. The reduction operation is subject to easy accurate control by regulation of the input of particulated magnesium metal and removal o'f reaction heat. The magnesium is not fed onto an already reacting body of magnesium instead 'the magnesium reacts with the halide vapor without hindrance 'from the magnesium supply for the reaction because theV pile or train of magnesium particles used in the reduction is formed in the reaction zone before the reaction occurs. The reaction is confined to the surfaces of the particles of magnesium in the pile or train; hence the walls of the reaction vessel enclosing the halide vapor to be reduced do nnot become fouled up with metal reduced from the halide. The reaction or" the magnesium with the halide vapor can be carried out upon horizontal or sloping surfaces without confining sidewalls because the magnesium is in patriculate form and the particles neither run together nor off the surfaces.

We claim:

l. The method of producing titanium sponge by reacting magnesium with titanium tetrachloride which comprises depositing upon a supporting surface in an atmosphere containing titanium tetrachloride vapor a pile of magnesium in particulate form, said surface having a temperature above the melting point of magnesium chloride whereby the magnesium particles burn in the titanium tetrachloride vapor forming titanium sponge in situ and molten magnesium chloride; removing vheat from the burning pile at a rate sullcient to maintain the burning at a smoldering pace; and draining molten magnesium chloride from the pile as it Smolders.

2. The method of producing titanium sponge by reacting magnesium with titanium tetrachloride which comprises depositing upon a supporting surface in an atmosphere containing titanium tetrachloride vapor a pile of magnesium in particulate form, said surfaces having a temperature above the melting point of magnesium chloride whereby the magnesium particles burn in the titanium tetrachloride vapor forming titanium sponge in situ and molten magnesium chloride; removing heat from the burning pile at a rate suflicient to maintain the burning at a smoldering pace; draining molten magnesium chloride from therpile as it Smolders; and removing the resulting titanium sponge from the.supporting surface.

3. The method of reacting magnesium with titanium tetrachloride vapor which comprises catching a falling stream of particulated magnesium on a heat-absorbing surface moving in a direction sideways of the stream so as to form an elongated shallow pile ,of Vparticulated magnesium on the said surface, said falling stream of particulated magnesium having a temperature below that at which the particles spontaneously ignite in titanium tetrachloride vapor while providing the pile with an ambient atmosphere comprising titanium tetrachloride vapor; maintaining the said heat-absorbing surface at a temperature of at least 708 C., whereby the portion of the pile remote from the point receiving the falling stream becomes heated and smolders on the said surface in the said atmosphere producing molten titanium sponge in situ and moltenA magnesium chloride, a portion of said molten magnesium chloride dripping oif the heat-absorbing surface as the particles smolder, the smoldering progressing along the pile toward the point of formation; removing heat from the smoldering portion of the pile through the said heatabsorbing surface at a rate sufficient to prevent the smoldering portion of the pile from bursting into flame, the rate of sideways movement of the heat-absorbing surface being equal to the average rate of progression of the smoldering along the pile; and removing from the heatabsorbing surface the so-formed titaniumr sponge beyond the smoldering portion. j

4. The method of producing titanium sponge by Vreacting magnesium with titanium tetrachloride which comprises depositing upon a supporting surface in an atmosphere containing titanium tetrachloride vapor a pile of magnesium in particulate form, said surface having a temperature above the melting point of magnesium chloride whereby the magnesium particles burn in the titanium tetrachloride vapor forming titanium sponge in situ and molten magnesium chloride, a portion of said molten magnesium chloride dripping off the supporting Vsurface as the magnesium particles burn; removing heat from the burning pile at a rate sufficient to maintain the burning at Ia smoldering pace; collecting in a pool the magnesium chloride which drips oif the supporting surface; and withdrawing the so-produced titanium sponge from the reaction zone through the said pool.

5. The method of producing titanium sponge by reacting magnesium with titanium tetrachloride which comprises forming an atmosphere containing titanium tetrachloride vapor in a reaction zone; depositing upon a heat-absorbing surface in the said zone above the bottom thereof a pile of magnesium in solid particulate form, said surface having a temperature above the melting point of magnesium chloride, whereby the magnesium particlesburn in the Said atmosphere forming titanium sponge in situ and molten magnesium chloride, a portion of said molten magnesium chloride dripping off the heat-absorbing surface as the magnesium particles burn; removing heat from the burning pile at a rate suicient to maintain the burning at a smoldering pace; collecting in a pool below the heat-absorbing surface the portion of the magnesium chloride which drips off the heat-absorbing surface; and scrap- 'l0 Y ing the titanium sponge so-formed olf the heat-absorbing surface into the said pool. p

6.'The method of reacting magnesium with titanium tetrachloride vapor which comprises catching a falling stream of particulated magnesium on a heat-absorbing surface moving in a direction sideways of the stream so as to l.

form an elongated shallow pile of particulated magnesium on the said surface, said falling stream of particulated magnesium having a temperature below that at which the particles spontaneously ignite in titanium tetrachloride vapor while providing the pile with an ambient atmosphere comprising titanium tetrachloride vapor; maintaining the said heat-absorbing-surface at a temperatur-enf at least 708 C., whereby the portion of the pile remote from the point receiving the falling stream becomes heated and Smolders onV the said surface in the said atmosphere producing titanium sponge in situ and molten magnesium chloride, a portion of said molten magnesium chloride dripping off the heat-absorbing surface as the. vparticles smolder, the smoldering progressing along the pile toward the point of formation; removing heat from the smoldering portion of the pile through the said heat-absorbing surface. at a rate sufficient to prevent the smoldering portion of the pile from bursting into flame, the ratel of sideways movement of the heat-absorbing surface being equal to the average rate Vof progression of the smoldering along thepile; collecting in a pool below the heat-absorbing surface the magnesium chloride which drips olf the heatabsorbing surface; and removing from the heat-absorbing surface the so-formed titanium sponge beyond the smoldering' portion.

References Citedin the le of this'rpatent UNITED STATES PATENTS 1,321,684 Turner ,Nov. 11, 1919 1,373,038 Weber Mar. 29, 1921 1,558,965 Clevenger Oct. 27, 1925 2,205,854 Kroll .Tune 25,` 1940 2,564,337 Maddex Aug.14, 1951 2,567,838 Blue Sept. 11, 1951 2,586,134 Winter Feb. 19, 1952 2,607,674 Winter Aug. 19, 1952 2,663,634 Stoddard Vet al Dec. 22, 1953 2,763,542 Winter Sept. 18, 1956 2,766,113 Chisholm et al Oct. 9, 1956 FOREIGN PATENTS l 386,621 Great Britain Feb. 16, 1933 832,205 Germany Feb; 21, 1952 686,845 Great Britain Feb. 4, 1953 OTHER REFERENCES Metal Powder Report, vol. 7, No. 4, December 1952, page 50. Y

Claims

1. THE METHOD OF PRODUCING TITANIUM SPONGE BY REACTING MAGNESIUM WITH TITANIUM TETRACHLORIDE WHICH COMPRISES DEPOSITING UPON A SUPPORTING SURFACE IN AN ATMOSPHERE CONTAINING TITANIUM TETRACHLORIDE VAPOR A PILE OF MAGNESIUM IN PARTICULATE FORM, SAID SURFACE HAVING A TEMPERATURE ABOVE THE MELTING POINT OF MAGNESIUM CHLORIDE WHEREBY THE MAGNESIUM PARTICLES BURN IN THE TITANIUM TETRACHLORIDE VAPOR FORMING TITANIUM SPONGE IN SITU AND MOLTEN MAGNESIUM CHLORIDE; REMOVING HEAT FROM THE BURN-