US3549140A - Apparatus for producing titanium and other reactive metals - Google Patents

Description

United States Patent Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-Flehr, Hohbach, Test, Albritton & Herbert ABSTRACT: A reaction vessel is provided with a three-outlet nozzle for discharging titanium chloride and molten magnesium entrained within an inert helium enveloping stream into a downwardly extending flame from the upper portion of the vessel. A closed loop recirculates a counterflow stream of inert gas through the reaction vessel which opposes the motion of the reactants from the nozzle, controls the formation and agglomeration of titanium metal, and lifts out and separates the chaff and carries it out in the counterflow stream, The heavier agglomerated metal shot produced in the reaction falls under gravity and its prior inertia to the bottom of the vessel where it is collected in a collecting chamber maintained under an inert atmosphere. The collection chamber includes means for densifying the metal before it is exposed to air.

[I] Cljw xg/aa 2 24 22 SHEU 1 BF 2 PATENTED 115022 1970 INVENTOR.

Da l Y Ingersoll 27 7M f M Attorneys This application ARPARATUS FOR PIiODUQING TITANIUM AND OTHER REACTIVE METALS V is a divisional of my copending application Sela; No. 648,061, filed June '22, l967, now US. Pat. No.

BACKGROUND OF THE INVENTION This invention relates to the production of titanium and other reactive metals and more particularly to the production of pure titanium by alkali metal reduction of its chloride.

- Many methods and apparatus for producing the pure base metal from reactive metal salts'are known. In one system for the? production of titanium metal the tetrachloride is reduced by an alkali metal at elevated temperatures to produce titanium sponge and alkali m'e'talchlorideucontrolled production and segregation of these products presents formidable problems because the'reaction must be carried out in an inert atmosphere or vacuum to prevent chemical reaction with or- 'diria-ry atmospheric compounds, such as oxygen or nitrogen.

Additionally, the metals ponge which is formed tends to retain included alkali chloride and requires-extensive handling and reprocessing, such as washing with aqua re'gia to remove impti r itie'sand multiple remelting under inert or vacuum atmospher'eto form the final metal ingotThere is, therefore, a

need for a new and improved method and apparatus for formthe above character which facilitates the recovery of the pure reactive metal substantially free of gaseous contaminants and 'co'incidently formed byproducts and unreacted raw materials.

. Another object of the invention is to provide a method and apparatus of the above character in which all the processing steps from the reduction step through the formation of the pure metal ingot are carried out within a common inert atmbsphere.

Another object of the inventionis to provide a method and apparatus of the above character which is particularly adapted for the" production of titanium metal from titanium chloride reduction with magnesiumor sodium; In general, however, the

method is applicable to any reactive metal whose halide is exothermically reduced to the base metal by a reducing metal such as magnesium or sodium.

"As used herein, inert atmosphere means an atmosphere which is unreactive with respect to the components of the reduction reaction being carried out. For titanium metal, atniospheres of helium or argon are satisfactory. Also, the term alkali metal (and the resulting alkali halide) is to be taken in a broad sense as including those reducing metals which can be used to exothermically reduce the refractory metal halide. This would include not only the group I alkali metals but also such alkaline-earth metals in group II as magnesium and calci- In general, the present invention makes use of a process and apparatus in which the base metal is produced from its halide by exothermic reductidn with an alkali metal in an inert atmosphere. The entire reaction is carried out within a vertically extending reaction chamber which also permits separation of the metal produced from the other reaction products and unreactedspecies. The process consists of forming the metal halide and alkali metal in'to fluid streams andcausing the streams to impinge in free space in the upper region of the reaction chamber to form a downwardly extending reaction torch in which the alkali metal reduces the metal halide and liberates cylindrical'envelope of inert gas which entrains the reactants and confines the reactionwithin a zone spaced from the walls of the reaction vessel.

The reaction chamber includes means for establishing a countercurrent flow of inert atmosphere upwardly through the vessel and means for withdrawing the countercurrent flow together with entrained materials from the upper region of the vessel. The material formed within the torch is expelled to form a stream of reaction'products falling-through the vessel under gravity and inertia of the entraining gas stream. This stream is cooled by the counterflow gas and its motion is opposed thereby. In so doing, the base metal is cooled and agglomerated into heavier solid particles while the other materials remain in fluid form or collect independently from the metal.

In a preferred form of the invention, the countercurrent stream is adjusted to avalue such that the metal agglomerate continues to fall to a collection zone near the bottom of the vessel. The chaff and other reaction products are separated from the downwardly falling stream by the force of the countercurrent flow gas for subsequent removal from the upper region of the vessel within the counterflow stream.

The reaction torch is formed by an injector nozzle which simultaneously delivers the components of the reaction entrained within a stream or envelope of inert gas so that the components impinge in free space below the nozzle. The metal halide and alkali metal are delivered to the regions within the stream of inertgas so as to react while being confined within the gas.

The foregoing objects and features of the invention will become apparent from the following description and claims when taken in conjunction with the accompanying drawings.

DESCRIPTlON or THE DRAWINGS FIG. '1 is an elevational view, partly in schematic, of one form of apparatus for carrying out the process of the invention.

FIG. 2 is a longitudinalcross-sectional view of the injector nozzle of the reactor of FIG. 1 taken along the lines 2-2 thereof.

FIG. 3 is an end view of the injector nozzle of FIG. 2 taken along the lines 3-3.

APPARATUS Referring to FIG. 1, the apparatus of the invention is shown and consists of a reaction'chamber 10 in which the reaction of the metal halide with reducing metal takes place. The reaction chamber consists preferably of an elongate upright cylindrical vessel 12 having a vertically extending cavity 14 therein. The lower end of the vessel is provided with conically converging walls 16 terminating in a discharge outlet 18 for metal produced in the vessel. The outlet 18 is provided with a diverting chute 20 for selectively discharging the metal product into either of storage bins 22 or 24. Storage bin 22 is used for the collection and segregation of contaminated (startup) metal and bin 24 is used to collect the pure metal formed during the main portion of a production run.

Means is provided for supplying an upwardly flowing coun-.

terstream 25 of inert atmosphere and includes an inlet plenum 26 provided about the lower end of the vessel and coupleds, through openings 28 therein into the lower region of cavity 14. Plenum 26 is connected to a source 27 of inert gas through suitable piping and valving. Counterflow stream 25 passes upwardly through the cavity 14 to the upper region thereof and is withdrawn through an outlet plenum 30 coupled through openings 32. A high volume pump 34 is connected in series in I a recirculating loop and delivers the atmosphere into inlet plenum 26, the pressure at the inlet plenum being indicated by.; pressure gauge 36 which can also be used to pressure test the system. Outlet plenum 30 is connected to a cyclone 38 one other efficient separator for removing entrained solid materials from the stream, solids output 40 of which is connected to a holding hopper 42. The gas outlet 44 of the cyclone is connected to a cooler and trap 46 for cooling the counterflow stream and for collecting unreacted metal halide therefrom. Cooler and trap 46 includes a heat exchanger connected to a source of refrigeration such as a cooling water supply (not shown) through inlet and outlet connections 48, 49 and is provided with trap discharge outlet 50. The stream of inert atmosphere is delivered downwardly and is supplied to the inlet of the high-volume pump 34 to form a closed loop for recirculating the inert atmosphere. Suitable means 51 is provided for selectively connecting the inlet plenum 26 and collector enclosure 100 to a source of vacuum.

Means forming a bypass loop 52 provides a source of inert atmosphere to a high-pressure pump 54, the output of which is connected to one input 56 of an injector nozzle 60 supported at the top of the vessel 12.

INJECTOR NOZZLE Referring particularly to FIGS. 2 and 3, there is shown in detail the construction of an injector nozzle 60 suitable for practicing the invention. Thus, the nozzle 60 consists of means for simultaneously delivering three fluids to its discharge end in separated streams. Such means includes an outer tubular member 62 which can also serve as the principal support for the other members by suitable connections. Disposed within the outer tubular member is an intermediate tubular member 64 which, together with member 62, defines an outer annular opening or outlet 66 for discharging a cylindrical envelope of inert gas. An inner tubular member 68 is mounted within the intermediate tubular member 64 and forms therewith an intermediate annular opening 70 surrounded by portions of the outer annular opening 66. Member 68 also provides a discharge orifice 72 located within the intermediate annular opening 70. Suitable piping 74 connects the inner tubular member and orifice 72 to a source 75 of molten magnesium and piping 76 connects the annular opening 70 to a source 77 of metal halide. For simplicity and concreteness in the follow ing discussion, it will be assumed that reduction of titanium tetrachloride with molten magnesium is being carried out in an atmosphere of helium.

As shown (FIG. 2), the inner tubular member 68 projects beyond both the outer and intermediate tubular members and preferably the intermediate tubular member 64 projects somewhat beyond the end of the outer tubular member 62. As will be explained, the relative length of the members aid in defining the dimensions of the reaction zone which is developed in the operation of the apparatus.

When in full operation, the reaction flame or torch zone of the reaction appears as shown in greatest detail in FIG. 2. Thus, titanium tetrachloride is supplied in an annular stream 80 surrounding a stream 82 of molten magnesium. Both streams 80, 82 are surrounded by an annular stream 84 of high-pressure helium. Streams 80, 82, 84 are separately discharged into free space and remain separate at the tip of the nozzle and for a small distance beyond. A partial vacuum may be said to exist at points 86 between the metal stream and the titanium tetrachloride stream and 88 between the titanium tetrachloride stream and the inert gas stream. These partial vacuum regions 86, 88 as well as the relative projection of the members 62, 64, 68 provide separation of the streams, propulsion for the reactants and direct the reactant streams to a focus at 90 where the streams fully impinge and reaction takes place. A sight port 91 can be provided at the upper region of the vessel so that the flame produced by the reaction can be visually observed. OPERATION Operation To operate the apparatus, the system is purged of air and moisture as completely as possible'and circulating counterflow stream 25 of inert gas is started. Stream 25 is recycled upwardly through the reaction vessel 12, the cyclone separator 38, cooler and trap 46 and blower or pump 34. Blower 34 is preferably equipped to adjust the volume of the counterflow stream to compensate for temperature and density variations in the gas stream. The system is tested for leaks by supplying inert gas through a valve to the system and observing the pressure drop that results when valve is turned off. When the system is leaktight, the high-pressure helium stream 84 is started so that all circulating inert gas can be purified at once.

To purify the system, a small stream 82 of molten magnesium is introduced into the high-pressure inert gas stream 84. Any oxygen, water vapor, or gaseous contaminants react with this molten magnesium, purifying the atmosphere to a great extent. The unwanted reaction products, as well as those later produced by the primary reaction, (hereinafter grouped together under the term chaff) are entrained in the counterflow inert gas stream and discharged from the vessel through the outlet 32 and are separated and collected in the separator 38. This chaff is anhydrous and is, accordingly, ideally suited to electrolytic recovery of the magnesium value.

At this time, stream of TiCl, is injected into stream 84 along with the molten magnesium. This initiates the primary reaction producing titanium metal and chaff consisting of MgCl unreacted magnesium metal, unreacted titanium chloride and other impurities, including titanium metal fines. The chaff consists of materials having a lower density than the pure metallic titanium and this constitutes a basis for separation. Complete separation of titanium fines is not required since the electrolytic treatment of the chaff will also recover it.

As the reaction stabilizes, the supply of molten magnesium and TiCL, is adjusted to produce a stable flame or torch which is directed down into reaction vessel, the products of the flame falling downwardly under gravity through the vessel where they are opposed by the countercurrent inert gas stream. This combination of flame and countercurrent flow provides the proper environment for the sequential formation and agglomeration of the titanium metal, and for separation of the reaction products. For convenience, the following discussion will consider the successive regions through which the products fall as distinct zones.

1. High temperature zone 92, (temperature over 3,300 F.) In this zone the titanium metal is molten and the other products are gaseous. As the titanium cools to 3,300F., it solidifies and agglomerates into nodular or spherical particles, called shot and represented by small circles in the drawings.

2. Midtemperature zone 94, (temperature 1,300" to 2,600 F.) In this zone MgCl is forming liquid droplets which solidify when they reach their fusion temperature. Under most conditions these will tend to collide with each other and so enlarge rather than collect upon the previously-formed metal shot because the metal shot remains at a higher temperature than the gas stream even though the temperature of the gas stream at this point is cool enough to solidify the molten MgCI In this zone the velocity of the entraining high-pressure, highvelocity inert gas stream is still high enough to propel and carry the entrained MgCl through the counterflow gas stream.

3. Low temperature zone 96, (temperature below 1,300 F.) In this zone the droplets of unreacted magnesium, which condense at about 2,000 F. and may be mixed with MgCl become solidified. It is also in this zone that the momentum developed in the torch and its entraining gas stream become dissipated by the continuous resistance of the counterflow gas stream 25.

4. Reversal zone 98. At the bottom of the reaction flame the momentum and velocity of all the reaction products are considerably reduced. At this point, the counterflow stream 25 and entraining gas stream 84 are balanced. Below this, the heavier titanium shot continues falling to the bottom of the vessel for collection; but, the lighter chaff, represented by dashes, becomes entrained in the counterflow stream and is carried up the periphery of the vessel to be discharged through the openings 32 to cyclone separator 38, as previously explained.

Preferably, there is also provided an enclosure having a collecting chamber 102 containing collection bins 22 and 24 and a processing chamber 104 separated from chamber 102 by a gastight bulkhead 106 and door 108. Each of chambers 102, 104 has a connection to inert gas supply and vacuum 21 so that the atmosphere in either area can be purified independently of each other and the rest of the system. The collecting chamber 102 can also have electrical and cooling liquid connections for permitting melting and cooling of the raw product into buttons for hardness testing and quality control.

Chamber 104 is equipped with devices for molding pressing, sinterlng, and welding, so that the titanium shot can be densified and/or alloyed, pressed into bars or discs sintered to increased strength, and welded together toform bars, rods or billets suitable for use as consumable electrodes for melting, billets for forging or other forms. Alternatively, the metal could be fed directly, under the same atmosphere, to a suitable melting furnace. The metal formed from the above will have superior properties and purity. since they are formed from material not yet exposed to air or other gaseous contaminants. ln final form, the metal is cooled to ambient temperatures, and is removed by closing the gastight door 108 and ejecting it through a series of sphincter seals 1 10.

My invention allows the control of the extreme temperature and energy of the reaction by regulating the amount of reactants available for the reaction and by diluting, dispersing and cooling the reaction zone. The reactants, products, and byproducts are entrained in the cooling inert gas stream 84 and also, for a finite distance beyond the nozzle tip are enveloped and surrounded by this cooling stream which directs and propels the reaction while also restricting its expansion. By adjusting the supplies of titanium tetrachloride, reducing metal, and inert gas, the reaction is easily regulated to proper rate.

Thus, there has been provided a new and improved method and apparatus for continuously producing titanium metal in pure form and for separating it from the chaff within the reaction vessel. By removing the chaff immediately, the entire process is simplified and improved and many steps heretofore necessary, such as washing out the impurities with aqua regia, can now be eliminated. By maintaining the metal product under inert atmosphere until after densification is completed, the opportunity for impurities to be introduced by contact with air is greatly reduced.

While there is described herein a preferred method and apparatus for forming and separating the titanium metal, it will be understood that the invention is broader in concept. Of particular importance is the combined use of a confined downwardly extending reaction torch and a counterflow cooling stream to obtain the titanium metal agglomerate uncon taminated by included impurities. Thus, the invention could be modified to remove all the reactants in the counterflow stream or at the bottom of the vessel and separate the pure titanium shot by pneumatic, mechanical, electrostatic or other means.

To those skilled in the art to which this invention relates many modifications and adaptations of the invention will occur. For example, while an annular coaxial configuration of nozzle discharge has been disclosed other configurations exist that can be used to produce similar results. Thus, a plurality of jets spaced about a circle could be substituted to form an annular inert gas stream, or the molten magnesium and titanium chloride could be introduced entrained in separate linear inert gas streams having intersecting paths within a second inert gas stream or as multiple coherent streams. Furthermore, the invention is adapted to the production of many other refractory metals such as zirconium, hafnium and the like which may be reduced by magnesium or other alkali metals such as sodium and calcium. Accordingly, the disclosure and descriptions herein are to be taken as illustrative of the invention and not as a limitation thereof.

I claim:

1. In apparatus for producing a metal from its halide by exothermic reduction with an alkali metal in an inert atmosphere and for separating the metal so roduced, means forminga vessel having a vertically exten ing interior cavity, a fluid dispensing nozzle mounted in said vessel in an upper region within said cavity, said nozzle including an inner tubular member having an unobstructed discharge outlet surrounded by an intermediate tubular member forming an annular opening therewith, said inner and intermediate tubular members serving to inject separate streams of reactants into said vessel to impinge in free space within said cavity, said nozzle also including an outer tubular member surrounding said inner and intermediate tubular members, said outer tubular member serving to direct a high-pressure stream of inert gas so as to envelope and contain said impinging streams of reactants, a discharge opening in a lower region of said vessel for removal of metal from the bottom of saidvessel, means forming an inert gas inlet in a lower region of said vessel, means forming an inert gas and chaff outlet in an upper region of said vessel, means forming a closed loop with said inlet and outlet means for continuously circulating an atmosphere of inert gas, said loop including a separator for removing chaff.

2. Apparatus as in claim 1 further including a means forming a bypass loop connected from said closed loop to said nozzle for supplying inert gas thereto.

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