US2826492A

US2826492A - Process and apparatus for producing titanium metal continuously

Info

Publication number: US2826492A
Application number: US414821A
Authority: US
Inventors: Morash Norman
Original assignee: Nat Lead Co
Current assignee: NL Industries Inc
Priority date: 1954-03-08
Filing date: 1954-03-08
Publication date: 1958-03-11
Anticipated expiration: 1975-03-11

Description

PROCESS AND APPARATUS FOR PRODUCING TITANIUM METAL CONTINUOUSLY Filed March '8, 1954 2 Sheets-Sheet 1 INVENTOR Norman Morosh FIGJ AGENT N. MoRAsH PROCESS AND APPARATUS FOR PRODUCING TITANIUM METAL CONTINUOUSLY Filed March 8, 1954- March 11, 1958 2 Sheets-Sheet 2 INVENTOR Norman Morush BY 7 dv lfl m AGENT PROCESS AND APPARATUS FOR mam-Jase TITANIUM METAL CONTINUOUSLY States Patent F Norman Morash, Westfield, N; 1]., assignor to National Lead Company, New York, N. Y., a corporation of This invention relates in general to a method for producing a refractory metal from a refractory metal halide and specifically to a process and means for producing a titanium metal compact of continuous length by reacting titanium tetrachloride with molten alkali metals or alkaline earth metals including magnesium, the instant inyention being an improvement over the process and apparatus disclosed and claimed in the 'copending application of Schmidt et al., Serial No. 349,222, filed April 1:6, 1953, for Continuous Process for Production of Titanium Metal which has been assigned to the assignee of the instant application.

As pointed out in said copending application, the processes which have heretofore been developed for producing titanium metal by reduction of titanium tetrachloride with alkali metals and alkaline earth metals including magnesium have been, for themost part, batchtyp'e operations. For example, the Kroll Patent No. 2,205,854, June 25, 19 40, and the Schle'chtenet al. Patent No. 2,482,127, September 20, 1949, describe methods for producing titanium metal by reacting titanium tetrachloride with a molten alkaline earth metal in a reaction pot whereby a titanium metal product is formed which c'omprises a hard metallic sponge-lLce mass of material. It is characteristic of these processes that the metallic sponge adheres tightly to the walls of thereaction pot and can be removed therefrom only at great expense, lossjoftime and impairment of the quality of the titanium metal. Other examples of current efforts to produce titanium metal are the Maddex Patent No. 2,564,337, August 14, 1951, and the Winter, In, Patent No. 2,586,134, February 19, 1952, each of whichis directed towards the production' of refractory metals in a manner to avoid the distinct disadvantages of a batch type process,

The copending application of Schmidtet al.,de scribes and claims a process andapparatus for producing refractory metal billets ofcontinuous length While utilizing a reciprocating ram which periodically collects andcom presses the refractory metal in the reaction vessel to form'successive compacts which, in turn, are integrated and expelled from the reaction vessel as a billet of continuous length.

, An object of the instant invention isto. provide an proved method and means for producing a, high qi'ia ty refractory metal compact substantially cont'i nously Another object of the invention is to provide an proved method for consolidating and reeoverin g titanium metal from a molten salt bath as a, titaniutn metal compact of substantially continuous length. v,

A still further object of the mention is to provide improved means for continuously forming andexpelling a titanium metal billet from the molten salt bath of a reactor of the type herein described. i p

These and other objects of the instantinventlion will become more apparent from the following' more 'com plete description and the accompanying drawings in whichy Figure 1 is a schematic front elevation, partly in sec- 6 2,826,492 Pi'atente d Mar. 11, 1958 7 2 tion, of apparatus of this invention for producing a titanium metal campact substantially continuously.

Figure 2 is anenlarg'ed fragmentary view of the reaction chamber'sh'own in Figure 1 including details of the compact expelling screws; and

Figure 3 is a transverse sectional view of the apparatus on line 33 of Figure 2. e In its broadest aspects, the present invention relates to an improved process for forming a refractory metal continuously by reacting a halide of the refractory metal with a molten metallic reducing agent in a molten salt bath to form a refractory metal in the molten salt bath; and continuously consolidating the refractory metal as it is formed in the bath while simultaneously, expelling it therefrom as a refractory metal compact of continuous length.

More specifically, in accordance with the instant inventhan, the substantially continuous production of a refractory metal, such as, for example, titanium metal, is effected by providing a molten salt bath in a reaction chamber having an open bottom end, charging the molten salt bath with a reducing agent such as sodium or magnes'ium metal, and introducing titanium tetrachloride to form titanium metal dispersed throughout the molten salt bath; and continuously consolidating the titanium metal inth'e bath to form a titanium metal compact therein which is simultaneously expelled from the bath and from the bottom end of the vessel'as a single integrated titanium metal compact of continuous length, sometimes referred to hereinafter as a titanium metal billet.

In one specific embodiment of the invention involving thepreparation of substantially pure titanium metal, a molten salt bath comprising a molten metal halide, preferably magnesium chloride, is provided within a suitable reaction vessel which, as shown schematically in Figure l, is an open ended metallicreaction vessel 8 formed of stainless steel or other suitable type of metal and having, in cross section, the configuration of two intersecting circles. The inside dimensions of the vessel may be uniform throughout its length, but superior results have 'been achieved by forming its lower end, sometimes hereinafter referred to as the tail-pipe portion 9 thereof, as shown in Figure. l, with progressively larger internal dimensions so that the metal billet may free itself from the walls of the vessel as the billet is expelled therefrom.

The inside of the reaction vessel above the tail-pipeporti'on 9 thereof constitutes a reaction chamber 10, the bottom end of which is open but provided with removable clo-sure means 11 which is preferably in the form of a metal endplug designed to conform in cross section to the cross section of the reaction vessel 8 so as to fit up into the open bottom end thereof; and adapted to be displaceably held therein by suitable counterbalancing means such as indicated schematically at 12 in Figure l. of the drawings. The counterbalancing means 12 is adapted to permit constant downward displacement of the end-plug 11 during expulsionof thecompact and, as hereinafter described, simultaneously to exert sufficient force upwardly against the refractory metal compact such that the particles of refractory metal in the bath will be effectively compacted by the action of the screws and the entrained salts pressed out of the compact. A hydraulic piston operating under a steadily decreasing volume of air may be used, but for simplicity of illustration, a fulcrumed lever of the first class is shown wherein the weight W represents a constant force acting to displaceably support the end-plug 11 in the open bottom end of the reaction chamber.

The salt bath 13 is composed of a halide salt of a metal or metals selected from the group consisting of the alkali metals alkaline earth metal including magnesium. It will be found convenient, whenever practical, to employ a product of the reduction as the salt bath, for instance when titanium tetrachloride is being reduced with magnesium, the salt bath may be composed of magnesium chloride. The salt bath materials may be introduced into the reaction chamber before the cover 14 is put in positron, or may be charged into the chamber by way of a feed pipe, hereinafter described; and'are maintained in a molten condition therein by heat exchange means which, as shown especially well in Figure 1, may comprise a furnace arranged around and extending longitudinally of the reaction vessel and embodying a plurality of heating units of varying capacity to provide the heat necessary to maintain the molten salt bath within a preferred temperature range hereinafter described.

As shown especially well in Figure l, the lower end of the furnace 15 terminates at approximately the bottom end of the reaction chamber 10 such that the tail-pipe portion 9 of the reaction vessel is unheated, its overall length being such that the retention time of the compacted metal billet in the relatively cool tail-pipe portion of the reaction vessel will correspond substantially to the time required for the metal billet to cool down sufliciently both to freeze the salts entrained in the billet and to preclude contamination of the billet by the oxygen in the atmosphere. In this connection auxiliary cooling means, such as, for example, cooling coils 16, are arranged around the reaction vessel adjacent the upper end of the tail-pipe portion 9, which corresponds to the bottom end of the reaction chamber 10, to accelerate the dissipation of heat therefrom, if necessary, and hence provide positive control of the temperature in this critical region of the reaction vessel.

As indicated by the size and arrangement of the heating units of the furnace 15, the latter is designed in a manner to heat the reaction chamber, and hence the salt bath 13 non-uniformly, i. e. such that the temperature of the salt oath adjacent the lower end of the reaction chamber 10 is maintained at a minimum value corresponding substantially to the freezing temperature of the salt bath; and increases substantially uniformly upwardly to a maximum temperature in the upper regions of the bath for most etficient reaction between the halide of the refractory metal and the reducing metal. This temperature range will vary, of course, depending upon the melting points of the materials used to form the salt bath. In particular, when magnesium chloride is employed as the salt bath, the temperature gradient of the bath varies from the freezing temperature of the salt bath of about 712 C. adjacent the bottom end of the reaction chamber 10 to a maximum temperature of from about 880890 C. adjacent the top of the bath, the preferred average temperature of the salt bath in the reaction chamber being about 800 C. As pointedout above, the lowest temperature of the salt bath is substantially adjacent the bottom end of the chamber 10, corresponding to the lower end of the furnace 15 so that at and below this point the molten salt bath will freeze and automatically form an effective seal between the compact being formed in the open bottom end of the reaction chamber and the inner walls thereof.

Roughly then, the bottom end of the reaction chamber 10 corresponds substantially to the freezing level of the,

salt bath within the reaction vessel. Since collection and compacting of the titanium metal is carried out in the molten salt bath, the freezing level of the molten salt bath represents the very lowest point in the reaction chamber at which the titanium metal compact may be formed. Preferably, however, the end-plug 11 which serves tem- The reducing agent such as magnesium, calcium, sodium or other metal having a reducing potential greater than titanium may be charged into the molten salt bath from the top thereof either in the form of solid metal or in a molten condition.

Since the boiling points'of magnesium and calcium respectively are higher than the melting point of magnesium chloride, these reducing metals may be used successfully with a magnesium chloride salt bath. However, since the boiling point of sodium is lower than the melting point of magnesium chloride, it would be necessary, when using sodium as a reducing metal, to employ a salt bath comprising sodium chloride or a suitable eutectic having a melting'point lower than the boiling point of sodium. When magnesium metal is used as the reducing metal, it is charged into the reaction vessel in the form of solid rods or bars by way of a feed pipe 17, one end of which intersects the wall of the reaction vessel and the opposite end of which is provided with a pair of air locks, indicated generally at 18, whereby the rods of magnesium metal may be introduced successively into the feed pipe while excluding air from entering the reaction chamber. In the preferred construction shown, the longitudinal axis of the feed pipe 17 extends upwardly at an angle to the longitudinal axis of the reaction vessel, the inner end of the feed pipe intersecting the wall of the reaction vessel at a point above the top surface 19 of the molten salt bath 13.

The halide of the refractory metal, in this instance vaporous titanium tetrachloride, may be introduced in either of two ways, i. e. either above the upper surface of the molten salt bath or below the upper surface of the bath. Preferably, the titanium tetrachloride is fed into the molten salt bath 13 below the upper surface 19 thereof, by a feed pipe 20, which intersects the wall of the reaction vessel at a point well below the upper region of the salt bath, the longitudinal axis of the feed pipe 20 extending upwardly at an acute angle with the longitudinal axis of the reaction vessel. Although the feed pipe 20 is shown, for simplicity, substantially in the plane of the feed pipe 17, it will be understood that the two pipes may be in different vertical planes.

' As pointed out above, the titanium tetrachloride is fed into the bath preferably at a point below the upper surface thereof and although the titanium tetrachloride may be in liquid form, it is preferred to use gaseous titanium tetrachloride. To'this end suitable heating means, indicated generally at 21, may be provided for vaporizing a source 22 of liquid titanium tetrachloride which is conporarily as the bottom end-closure of the reaction chamber and against which the formation of a titanium metal compact is initiated, is, located within the reaction chamber at a point somewhat above the freezing level of the molten salt bath, and highly satisfactory results have been achieved when the end-plug 11 is located at a point in the chamber at which the temperature of the magnesium chloridesalt bath is from about'715-720" C.

nected by means of a flexible connection 23 to the feed pipe 20.. The feed pipe 20 may be wrapped or otherwise covered with suitable heat insulating material to prevent condensation of the gaseous tetrachloride therein.

Since the presence of oxygen in the reaction vessel dur ing the reaction is exceedingly detrimental to the quality of titanium metal produced, the titanium tetrachloride feed pipe is carefully sealed against the admission of oxygen into the reaction vessel. As one expedient to this end, suitable apparatus, indicated generally at 24, is connected to the outer end of the feed'pipe 20 to maintain helium or a similar inert gas in the feed pipe at all times so that whenever the vaporous titanium tetrachloride feed is shut off, sufficient helium gas is present in the feed pipe to preclude the entry of air or oxygen into the molten salt bath. In like manner, the inert atmosphere within the feed pipe precludes admission of the molten salt bath up into the open inner end thereof. The vertical distance from the inner end of the titanium tetrachloride feed pipe 20 to the upper surface 19 of. the salt bath 13 may vary to some degree, and'successful operation of the reactor has been achieved when the feed pipe enters the bath at r a 'pointnearer the bottom than the top of the bath.

control means comprising a tap pipe 25, the inner end of which, as shown especially Well in Figure 1, intersects the wall of the reaction chamber at substantially the height selected for the preferred level of the molten salt. The tap pipe 25 slopes downwardly and its outer end is provided with a removable closure 26 to permit the introduction of a clean-out rod or the equivalent for clearing the tap pipe in the event it becomes clogged. Intersecting the tap pipe adjacent its outer end is the upper open end of a substantially vertical delivery pipe 27, the upper end of which is provided with an extension 28 also capped. The capped ends of the

respective pipes

25 and 28 provide access to the interiors of the respective pipes for rodding or clearing the latter of any condensed materials deposited therein, but which, during normal operation, are capped to exclude the admission of air to the reaction chamber. Specifically, the material which overflows from the molten bath 13 comprises, in the main, molten magnesium chloride which is formed by reaction of the reduced chlorides of titanium with the molten magnesium metal. Hence, as the reaction proceeds the level of the molten magnesium chloride rises until it overflows into the tap pipe 25 and thence by way of the delivery pipe 27 into a heated recovery vessel 29. Since solidification of the molten magnesium chloride within the aforemenioned pipes would clog the pipes, the latter are designed not only so'that they may be readily rodded but are preferably insulated to insure free flow 'of the molten magnesium chloride therethrough. 7

Since molten magnesium metal has a lower specific gravity than that of molten magnesium chloride, one would expect it to float on the surface of the latter and be lost through the tap pipe 25. However, it is postulated and there is some evidence to indicate that particles of titanium metal attach themselves to the globules of molten magnesium metal, thereby increasing the specific gravity of the latter such that the globules of molten magnesium metal migrate toward the bottom of the bath. Consequently, no significant amount of molten magnesium metal is carried out of the bath by way of the overflow pipes.

Pursuant to the objects of the invention, the titanium metal which is being continuously formed in the bath by reaction of the reduced chlorides of titanium, i e. the dichlorides and trichlorides, with the globules of molten magnesium metal, is continuously consolidated, that is to say, brought together into the form of a single compact mass of material comprising substantially pure titanium metal. V

In brief, the consolidation of the titanium metal is effected continuously by the use of a pair of continuously rotating self-cleaning screws which are disposed in the reaction chamber 10, and dimensioned, as shown especially well in Figures 2 and 3, to maintain a free running fit with the walls thereof; and with adjacent flights of the screws in overlapping relationship. As the pair of screws rotate theyserve to collect the titanium metal being forme'd in the bath and carry it downwardly continuously to the bottom thereof; and simultaneously to compactithe titanium metal against the upper end of the aforementioned removable end-plug 11 (or previously compactedtitanium metal) at the bottom of the reaction chamber with sufiicient pressure to squeeze therefrom a large proportion of the inclusions of molten magnesium and/ or molten salt and form a substantially solid titanium metal compact. In addition, the continuously rotating .screws serve to continuously expel the compacted titanium metal from the bath by way of the open bottom end of the reaction chamber as a titanium metal billet of continuous length. 7

Referring to the drawings, the screws, which are indicated generally at 30-'30, are arranged with their longitudinal axes'in the vertical plane of the major axis of the reaction chamber (see Figure 3) and in spaced parallel relationship; and with the adjacent flights'3'1 of the respective screws in overlapping relationship, as shown especially well in Figure 2, by which arrangement the flights of each screw serve to clean off and otherwise preclude the accumulation of titanium metal particles on the flights of the other screw. The number of flights on each screw may vary but preferably the flights should extend substantially the entire length of that portion of the screw shaft which projects into the reaction chamber and in particular into the molten salt bath therein. It will be appreciated that during the operation of the reactor, innumerable discrete particles of titanium metal as well as incipient titanium metal sponge are dispersed throughout the molten salt bath and tend to accumulate on or freeze to the walls of the reactor as well as any other solid objects extending into the bath. Hence, it is imperativethat the screws be constructed as shown not only so that the perirneters of the flights of the screws will be disposed immediately adjacent the inner walls'of the reactionchamber, which to this end is formed to have, in cross section, the shape of two intersecting circles, and so that the flights of the screws will overlap throughout the portions thereof extending into the reaction chamber. While by and large the greater amount of titanium metal is formed in the molten salt bath, some is formed by reaction of the vapors which ascend into the upper end of thereaction chamber above the upper level of the bath and precipitate out on the upper walls and upper ends of the screws. Hence, the desirability of providing overlapping flights throughout the lengths of the screws. v

The lower ends of the screws are shown terminated at a point substantiallyhalf-way between the inlet of the feed pipe 20 and the bottom end of the reaction chamber, and while this disposition of the terminal ends of the screws is wholly satisfactory, it will be understood, that it 'is not critical and that variation thereof may be made and are contemplated within the scope of the invention.

The portion of the screws which extend upwardly above the upper end wall or cover 14 of the reaction chamber are hereinafter referred was the screw shafts 32. These screw shafts are rotatably supported in a bearing structure/Which, as shown especially well in Figure 1, comprises a bushing housing 33 mounted on the top of the cover 14 of the reaction chamber; and a cage 34 which extends upwardly from the cover 14 and is provided with transversem'emb'ers 35 which serve to support a pair of vertically spaced stabilizing bearings 36-36 and a thrust bearing 37, the lat ter being disposed substantially intermediate the stabilizing bearings. The bushing housing 33 is provided with suitable sealing glands to preclude the entry of air into the reaction chamber while the thrust bearings serve to support the shafts against vertical displacement.

The shafts 32 are adapted to be rotated in opposite directions and to this end are provided with a motor driven gear-train indicated generally at 38 which as shown is located above the upper stabilizing bearing. Above the gear-train, each shaft is provided with a sealed cap 39 rotatably engaged thereon and within which its respective screw shaft terminates, each cap having a pair of radially extending

pipes

40 and 41 respectively for delivering a coolant into and from the upper end of its shaft. 7

In this connection it should be explained that since the temperatures employed in carrying out the reaction in the reaction chamber are in the range of from 712 C.

to 890 C., it is preferable to cool the screws to prevent their distortion. Consequently, the screws are of hollow construction, that is to say both the shafts and flights are provided with passages therethrough, as shown especially well in Figure 2, whereby a coolant may be circulated through the shafts and flights to preclude over heating. Hollow flight screws of this general type have i been used in industry in other capacities, and consequently the structural details of the screws do not form a part of theinstant invention but are shown for clarity and as an illustration of one type of hollow flight screw 7 which may be used successfully for the continuous production of a refractory metal billet in the manner of this invention. 7 7

As shown, each screw shaft 32 comprises an inner tube 42 and an outer tube 43, the coolant being delivered by the inlet pipe 40 into the upper end of the inner tube 42 and passing down to the bottom end of the screw from which point the coolant returns upwardly through the hollow flights 31 and the annular passage between the inner and outer tubes into the sealing cap 39 at the upper end of the shaft and from thence into the outlet pipe 41.

Any suitable type of coolant may be used and preferably one which will not react adversely with the reaction products in the reaction vessel in the event of a leak or break occurring in one of these screws. Titanium tetrachloride is suggested as a satisfactory coolant since titanium tetrachloride is one of the reactants and consequently cannot be expected to cause any serious damage if inadvertently released into the reaction chamber. By circulating the coolant at a rate such as to maintain the temperature of the coolant preferably below its boiling point, although not necessarily so, the screws may be effectively cooled to preclude deterioration and destruction.

Although the drawings of the apparatus shown are schematic in nature, nevertheless they tend to illustrate the principal elements of a type of apparatus which may be used to produce titanium metal compacts. However, some modifications of the apparatus are contemplated within the scope of the invention, particularly changes whereby the overall height of the reaction chamber may be decreased such that shorter screws may be used perhaps to better advantage.

As pointed out above, the temperature of the salt bath varies throughout the bath and is critical for the successful operation of the reactor. This is particularly true of the temperature of the bath at the lower end of the reaction chamber where freezing of the salt bath must occur in order to insure a seal between the compact being formed and the open bottom end of the reaction chamber. For a magnesium chloride bath the freezing point is about 712 C. which is, therefore, the maximum permissible temperature of the bath at the open bottom end of the reaction chamber. If other salts are employed, then the freezing temperature of the bath would be different. For example, if a sodium chloride bath is employed, then the maximum temperature of the bath at the open bottom end of the reaction chamber would be about 800 C.

The process by which the titanium metal billet is formed using the apparatus of this invention is illustrated especially well in Figure l and described briefly as fol lows: The reaction vessel is made ready for operation by adjusting the counterbalance 1.2. so as to hold the steel end-plug ill in place in the bottom end of the reaction chamber 19 and preferably at a point at which the temperature of the bath is slightly above freezing, as for example about 7l5720 C. If available, it is preferred to drop a piece of titanium metal sponge into the reaction chamber onto the top of the end-plug 11 to serve as a starting material on which to form a compact in which instance the end-plug 11 would be located further down in the chamber so as to bring the titanium metal sponge at the aforesaid temperature level.

The molten salt bath R3 in the reaction chamber is prepared by adding crushed anhydrous magnesium chloride to the reactor and then heating the reactor to melt the anhydrous magnesium chloride and establish an average temperature in the molten salt bath of about 800 C. Heat is also applied to the magnesium chloride recovering vessel 29 to bring it up to a temperature of about 800 C., and similarly heat is applied to the titanium tetrachloride feed pipe and the magnesium chloride overflow pipes to prevent solidification of the respective compounds therein.

After purging the entire system of oxygen and other deleterious gases, by means of the-helium source 24 which is attached to the feed pipe 20, the valves of the titanium tetrachloride vaporizing chamber 22 are opened to admit vaporous titanium tetrachloride into the feed pipe.

For optimum performance, the titanium tetrachloride vaporizing chamber should be kept at a temperature from between 500600 C. and the feed pipe at a temperature between 300400 C.

The magnesium metal in the form of half-pound sticks is then added into the reaction chamber 10 from the air lock 18, the vaporous titanium tetrachloride being concurrently fed into the bath initially at a relatively low rate and subsequently at an increased rate as the reaction proceeds. The magnesium metal is preferably added in amounts of 5% excess over the theoretical amount to reduce the titanium tetrachloride introduced.

As the titanium metal begins to form in the bath, the motor driven screws 30-30 are started and turned continuously at a very slow rate of rotation so as to preclude sufficient agitation of the salt bath as would unify the temperature of the bath, as for example no faster than about 10 R. P. M., whereby the flights 31 of the screws collect and move the particles of titanium metal being formed in the bath downwardly to the bottom thereof. A coolant is simultaneously circulated through the screws in the manner hereinabove described. Molten magnesium chloride will have formed in the bath, and some of this molten magnesium chloride will penerate down between the walls of the reaction chamber and the end-plug 11, as indicated in Figure 2, but is effectively prevented from escaping from the lower open end of the reaction chamber by being frozen at a point substantially opposite the cooling coils 10 of the reaction chamber to form a seal.

As the reaction continues, the amount of titanium metal collected and compressed at the bottom of the chamber by the action of the screws steadily increases until a point is reached at which the compression exerted by the screws on the compacted metal exceeds the force supporting the end-plug 11 in the bottom of the reaction chamber. This force may be a combination of that exerted by the fulcrumed weight Wand the friction force of the frozen magnesium chloride. When the compression force exerted by the screws exceeds the aforementioned force which supports the end-plug 11 in the bottom of the reaction chamber, the end-plug together with the compacted titanium metal begin to move downwardly slowly through the tail pipe portion 9 of the reaction chamber, the magnesium chloride seal being constantly maintained by the freezing of the magnesium chloride as it reaches the bottom end of the reaction chamber substantially opposite the cooling coil 16. The speed of movement of the compact is governed, of course, by the rate at which the titanium metal is being collected and compacted by the continuously rotating screws. Once the compact has begun to move downwardly, its movement is continuous and steady, the force differential between the compacting force of the screws and the constant combined counteracting forces exerted by the fulcmmmed weight W and the friction force of the frozen magnesium chloride being sufficient to press substantially all of the molten magnesium chloride salts from the compact in the molten salt bath whereby the billet expelled fromthe tail pipe of the reactor is of remarkably uniform density and composition.

The billet comprises, in the main, substantially pure titanium metal and relatively minor amounts of'frozen salt which may be separated from the pure titanium metal by well known leaching and/ or distillation techniques. It

From the foregoing description it will be manifest that the process and apparatus of the present invention provides a continuous, relatively simple, inexpensive and highly productive method for producing titanium metal of high purity and ductility; and that the titanium metal billet is extruded as a continuous length of substantially solid metal from which impurities may be readily removed at minimum expense, thereby precluding the high losses of metal,

time and equipment which have characterized earlier batch methods for producing refractory metals.

Although the invention has been illustrated by its application to the production of titanium metal using magnesium as a reducing metal, it is within the purview of the invention to utilize other reducing metals, such as sodium; and to form other refractory metals, such as zirconium, from the halide of the metal by the process and apparatus hereinabove described.

While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto, and other variations and modifications may be employed within the scope of the following claims.

I claim:

1. A process for producing a refractory metal compact which comprises: providing a reaction bath consisting of a molten halide salt of a metal selected from the group consisting of the alkali metals and alkaline earth metals including magnesium; introducing a reducing metal into said molten metallic salt bath; feeding a halide of said refractory metal to said molten metallic salt bath and reacting said halide with said reducing metal to form a refractory metal in said bath; and continuously consolidating and compressing the refractory metal in said bath to produce therein and simultaneously expel therefrom a relatively dense refractory metal compact of continuous length.

2. A process for producing a refractory metal compact which comprises: providing a reaction bath consisting of a molten halide salt of a metal selected from the group consisting of the alkali metals and alkaline earth metals including magnesium; introducing a reducing metal into said molten metallic salt bath; feeding a chloride of said refractory metal to said molten metallic salt bath and reacting said chloride with said reducing metal to form a refractory metal in said bath; continuously consolidating and compressing the refractory metal in said bath to produce therein and simultaneously expel therefrom a dense refractory metal compact of continuous length; and maintaining a seal between said molten metallic salt bath and a portion of said expelled compact by freezing a portion of said salt bath.

3. A process for producing a titanium metal compact which comprises: providing a bath consisting of molten magnesium chloride; introducing magnesium metal into said magnesium chloride bath to form molten magnesium metal in said bath and reacting said titanium tetrachloride with said magnesium metal to form titanium metal in said bath; continuously collecting the titanium metal in said bath and continuously compressing the collected titanium metal in said bath with a compression force sufiicient to squeeze substantially all inclusions of said molten salt from said collected titanium metal and form a relatively dense titanium metal compact in said bath, said compression force being suflicient also to simultaneously expel said titanium metal compact from said bath.

4. A process for producing a titanium metal compact which comprises: providing a bath consisting of molten magnesium chloride in a reaction chamber; introducing magnesium metal into said magnesium chloride bath to form molten magnesium metal in said bath; heating said bath in a manner to provide a temperature gradient in said bath ranging from the freezing point of said magnesium chloride adjacent the bottom of said reaction chamber to a temperature of at least about 840 C. adjacent the upper end thereof; feeding titanium tetrachloride to said magnesium chloride bath and reacting said titanium tetrachloride with said magnesium metal to form titanium metal in said bath; continuously collecting and compressing the titanium metal into the bottom of said reaction chamber at a level above the freezing point of said magnesium chloride bath to produce therein and simultaneously expel therefrom a relatively dense titanium metal compact.

5. A process for producing titanium metal compact which comprises: providing a bath consisting of molten magnesium chloride in a reaction chamber having a removable end-closure adjacent its bottom end; introducing magnesium metal into said magnesium chloride bath to form molten magnesium metal in said bath; feeding titanium tetrachloride to said magnesium chloride bath and reacting said titanium tetrachloride with said magnesium metal to form titanium metal in said bath; continuously collecting titanium metal in said bath; continuously compressing the collected titanium metal in said bath against said removable end-closure with sufficient force to squeeze substantially all inclusions of said molten salt from said collecting titanium metal and form a relatively dense titanium metal compact in said bath, said compression force serving simultaneously to provide a pressure differential between the compact and the displaceable end-closure in a direction to effect displacement of said removable end-closure, thereby to displace the titanium metal compact continuously from said reactor chamber.

6. A process for producing substantially pure refractory metal which comprises: providing a bath consisting of a molten halide salt of a metal selected from the group consisting of the alkali metals and alkaline earth metals including magnesium; introducing a reducing metal into said molten metallic salt bath to form molten reducing metal in said bath and reacting a halide of said refractory metal with said reducing metal to form a refractory metal in said bath; continuously collecting and compressing the refractory metal in said bath to produce therein and simultaneously expel therefrom a relatively dense compact of refractory metal including entrained salts; and then treating said compact to separate the entrained salts from the refractory metal.

7. In a process for producing a refractory metal by reacting a multivalent halide of the refractory metal with a reducing metal in a bath consisting of a molten halide salt of a metal selected from the group consisting of alkali metals and alkaline earth metals including magnesium, the steps comprising: introducing the halide of said refractory metal into said bath to react with said reducing metal and form said refractory metal in said bath; and continuously collecting and compressing the refractory metal in said bath to form a relatively dense refractory metal compact therein and simultaneously to expel the refractory metal compact from said bath.

References Cited in the file of this patent UNITED STATES PATENTS 2,171,439 Von Zeppelin Aug. 29, 1939 2,271,960 Taylor Feb. '3, 1942 2,549,642 Seelig Apr. 17, 1951 2,564,337 Maddex Aug. 14, 1951 2,570,989 Seelig Oct. 9, 1951 2,618,550 Hampel et al Nov. 18, 1952 2,676,882 Hatch Apr. 27, 1954 2,753,254 Rick July 3, 1956 2,758,921 Schmidt Aug. 14, 1956 OTHER REFERENCES Hatch et al.: Abandoned application Serial No. 189,404, filed Oct. 10, 1950.

Claims

1. A PROCESS FOR PRODUCING A REFRACTORY METAL COMPACT WHICH COMPRISES: PROVIDING A REACTION BATH CONSISTING OF A MOLTEN HALIDE SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF THE ALKALI METALS AND ALKALINE EARTH METALS INCLUDING MAGNESIUM, INTRODUCING A REDUCING METAL INTO SAID MOLTEN METALLIC SALT BATH: FEEDING A HALIDE OF SAID REFRACTORY METAL TO SAID MOLTEN METALLIC SALT BATH AND REACTING SAID HALIDE WITH SAID REDUCING METAL TO FORM A REFRACTORY METAL IN SAID BATH, AND CONTINUOUSLY CONSOLIDATING AND COMPRESSING THE REFRACTORY METAL IN SAID BATH TO PRODUCE THEREIN AND SIMULTANEOUSLY EXPEL THEREFROM A RELATIVELY DENSE REFRACTORY METAL COMPACT OF CONTINUOUS LENGTH.