US2879984A - Apparatus with rotating element for metal production - Google Patents

Description

March 31, 1959 E. G. HELLIER 2,879934 APPARATUS WITH ROTATING ELEMENT F OR METAL PRODUCTION Filed Oct. 26, 1955 FIG.

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ATTORNEY United States Patent APPARATUS WITH ROTATING ELEMENT FOR METAL PRODUCTION Edward G. Hellier, Hingham, Mass, asslgnor to National Research Corporation, Cambridge, Mass., :1 corporation of Massachusetts Application October 26, 1955, Serial No. 542,859

6 Claims. (Cl. 266-34) This invention relates to the production of metals and more particularly to the production of refractory metals such as titanium, zirconium and the like. This application is in part a continuation of my application Serial No. 442,525, filed July 12, 1954, now abandoned.

A principal object of the present invention is to pro vide improved apparatus for growing relatively large crystals of a refractory metal such as titanium by the reduction of a compound of the refractory metal dispersed in a fused salt bath.

Another object of the invention is to provide apparatus of the above type which gives a relatively high yield of relatively large crystals of titanium by the reduction of a titanium compound dissolved in a fused salt.

Other object of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the apparatus possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

Fig. 1 is a diagrammatic, schematic embodiment of one form of the invention;

Fig. 2 is a diagrammatic, enlarged sectional view taken along the line 2-2 of Fig. 1; and

Fig. 3 is a diagrammatic, sectional view taken along the line 33 of Fig. 2.

The present invention is particularly directed to improved apparatus for the production of refractory metals in the form of relatively large crystals which can be readily water leached. For convenience of illustration, the invention will be initially described in connection with apparatus specifically designed for the production of large crystals of titanium by a process wherein a titanium halide, preferably a titanium lower chloride, is dissolved in a fused salt comprising sodium chloride and this lower chloride of titanium is reduced to titanium metal by means of a reducing agent such as sodium. This specific embodiment is given for illustrative purposes only without intent to limit the scope of the invention.

In a preferred form of apparatus embodying the invention, a chamber is provided for holding a fused salt bath which contains a compound of the metal (e.g., titanium) to be produced. As mentioned above, this salt bath is preferably sodium chloride and a lower chloride of titanium is preferably the dissolved titanium compound. The reactor also preferably includes a means for distributing the reducing agent (e.g., sodium) in a uniform fashion across the surface of the fused salt bath so that the sodium can enter the bath uniformly across the whole upper surface, at least during the initial stages of the reduction reaction. This sodium distribution means comprises a metallic element which is tions.

This disc-shaped element is mounted above the surface of the fused salt bath. The apparatus also includes means for rotating the disc-shaped element about an axis which is substantially normal to the fused salt bath so that the disc rotates in a plane substantially parallel to the fused salt bath surface. Due to the cutaway portions, the circumference of the disc varies from a circle so as to provide portions thereof having dilferent radii. Means are also provided for feeding liquid sodium to the disc near its axis so that the sodium will travel outwardly across the upper surface of the disc by centrifugal force. Since the sodium will leave the disc from various portions of the circumference thereof which have different radii, the droplets of sodium leaving the disc will have different horizontal velocities, the velocities being a direct function of the distance from the axis to the points of departure.

The disc is also preferably provided with a means for assuring feed of most of the sodium to the points on the disc of greatest radii. Accordingly, the amount of sodium leaving any point on the circumference of the disc is a direct function of the square of the distance between that point and the axis of the disc. This differential feed is preferably achieved, in a preferred embodiment of the invention, by providing spiral grooves on the upper surface of the disc, the spirals being arranged to feed the greatest quantities of sodium to circumferential points having the greatest radii. The arrangement described above gives a particularly uniform distribution of sodium over a relatively large surface area of the molten salt. Since, in one preferred embodiment, the level of the fused salt bath will rise during the reduction period, the apparatus also includes a means for measuring the level of the fused salt bath. The apparatus also preferably includes a means for increasing the speed of rotation of the disc as the level rises to give a flatter trajectory to the sodium droplets. Accordingly, the complete surface of the fused salt will be covered, even though the level thereof has risen substantially.

Referring now to the drawing, there is illustrated one embodiment of the invention wherein 10 represents the reactor made of nickel or the like, having a top 12 which can be water cooled, if desired. In a preferred embodiment of the invention, the reactor is the type described in the copending application of Vaughan, Serial No. 441,108, filed July 2, 1954. The reactor includes a reaction space 14 containing a charge of fused salt 16 which, in the preferred process mentioned briefly above, comprises a solution of lower titanium chlorides in sodium chloride. The reactor may also contain a grid 17 for supporting the titanium crystals formed during the reduction operation. The means generally indicated at 18 for distributing the sodium over the surface of the fused salt 16 preferably includes the disc-shaped metallic element 20 carried by a rotatable shaft 22 and a feed tube 24 for feeding sodium 25 to disc element 20. The shaft 22 is driven by a variable speed motor 21 controlled by a suitable level-measuring device. This level-measuring device is preferably a radioactive source 23a arranged to be scanned by a radiation-sensitive element 23. One such method of level measurement is shown in US. Patent 2,647,826 to Jordan. As the level of the melt rises, the level-measuring device 23 increases the speed of the motor 21 so that the area covered by the fed sodium remains substantially constant even through the distance between the disc 20 and the surface of the salt bath decreases. As seen best in Figs. 2 and 3, disc element 20 has cutaway portions 26 so that the circumference of the disc-shaped element 20 is not a circle but has circumferential portions of different radii capable of imparting different horizontal velocities to droplets 25 of sodium flung from the disc at the points of different radii. The disc-shaped element 20 also preferably includes spiral grooves 28 which are so designed as to cause larger amounts of sodium to be thrown from points of the greatest radii with respect to the shaft axis. In other words, most of the sodium is fed to those points on the circumference of the disc 20 which are spaced the farthest distances from the axis 22. As can be seen best in Fig. 3, the spiral grooves 28 are so designed that the size of the groove increases as a function of its length. Thus the grooves extending to the outer portions of element 20 are the deepest so as to carry the greatest amount of sodium. The same effect can be achieved by varying the width of the grooves. Alternatively, the spirals can be of uniform size with more spirals being provided for feeding sodium to each unit of circumference as the radius increases. Accordingly, the amounts of sodium thrown from the various points on the disc increase with the square of the radii of these points so that the sodium will fall uniformly on the surface of the melt 16.

The above arrangement provides a solid cone of sodium spray which covers the surface of the molten salt bath. As the level of the salt bath rises, the cone is flattened by increasing the shaft speed so that sodium is still fed to the outer circumference of the bath.

In a preferred embodiment of the invention, the disc 20 and shaft 22 are preferably formed of titanium, this being particularly true when titanium is the refractory metal to be produced and when any titanium tetrachloride is present. This latter condition will be found in those cases where titanium tetrachloride vapor is reduced to titanium dichloride or titanium trichloride by sodium within the reactor 10, this being one preferred method of making the mixture of titanium dichloride and sodium chloride. In this method of operation, a feeding tube (not shown) may be provided for feeding the titanium tetrachloride into the reactor 10. In this embodiment of the invention, it is also preferred to provide a stirrer (not shown) for agitating the molten salt bath 16 during the formation of the sodium chloride-titanium dichloride mixture. While titanium is the preferred metal for constructing the disc 20 and the other elements of the sodium feed system, other refractory metals such as zirconium, tantalum and the like may be employed. Additionally, while a fiat disc is the simplest type of construction, it should be apparent that the element may take the shape of a pyramid or cone without detracting from the essential features of the invention. Equally, numerous modifications of the specific type of spiral illustrated can be provided.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description, or shown in the accompanying drawing, shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for producing crystalline refractory metal by reduction of a refractory metal compound dissolved in a fused salt bath, the apparatus comprising a reaction chamber for holding a fused salt bath, a metallic element mounted above the surface of the fused salt bath, means for rotating the element about an axis sub stantially normal to the fused salt bath so that the element rotates in a plane substantially parallel to the fused salt bath surface, and means for feeding a liquid metal reducing agent to the element near the axis of rotation thereof, the circumference of the element varying from a circle to provide portions of different radii capable of imparting different horizontal velocities to droplets of reducing agent flung from the element at the point of different radii.

2. Apparatus for producing titanium by reduction of a titanium compound dissolved in a fused salt bath, the apparatus comprising a reaction chamber for holding a fused salt bath, a titanium disc mounted above the surface of the fused salt bath, means for rotating the disc about an axis substantially normal to the fused salt bath so that the disc rotates in a plane substantially parallel to the fused salt bath surface, and means for feeding a liquid metal reducing agent to the disc, the circumference of the disc varying from a circle to provide portions of different radii capable of imparting different horizontal velocities to droplets of reducing agent flung from the disc at the points of different radii.

3. Apparatus for producing crystalline refractory metal by reduction of a refractory metal compound dissolved in a fused salt bath, the apparatus comprising a reaction chamber for holding a fused salt bath, a metallic disc mounted above the surface of the fused salt bath, means for rotating the disc about an axis substantially normal to the fused salt bath so that the disc rotates in a plane substantially parallel to the fused salt bath surface, and means for feeding a liquid metal reducing agent to the disc, the circumference of the disc varying from a circle to provide portions of different radii capable of imparting different horizontal velocities to droplets of reducing agent flung from the disc at the points of different radii, the means for feeding the liquid metal reducing agent to the disc and the surface of the disc being arranged to provide feed of the greatest amounts of liquid reducing agent to points of greatest radii on the disc.

4. Apparatus for producing crystalline refractory metal by reduction of a refractory metal compound dissolved in a fused salt bath, the apparatus comprising a reaction chamber for holding a fused salt bath, a metallic element mounted above the surface of the fused salt bath, means for rotating the element about an axis substantially normal to the fused salt bath so that the element rotaes in a plane substantially parallel to the fused salt bath surface, and means for feeding a liquid metal reducing agent to the element, the circumference of the element varying from a circle to provide portions of different radii capable of imparting different horizontal velocities to droplets of reducing agent flung from the element at the points of different radii, the surface of the element having grooves for guiding the liquid metal outwardly in a non-uniform fashion so that the amount of reducing agent leaving a point on the circumference having a given radius is a direct function of the square of the radius at that point.

5. Apparatus for producing crystalline refractory metal by reduction of a refractory metal compound dispersed in a fused salt bath, the apparatus comprising a reaction chamber for holding a fused salt bath, a metallic element mounted above the surface of the fused salt bath, means for rotating the element about an axis substantially normal to the fused salt bath so that the element rotates in a plane substantially parallel to the fused salt bath surface, and means for feeding a liquid metal reducing agent to the element, the circumference of the element varying from a circle to provide portions of different radii capable of imparting different horizontal velocities to droplets of reducing agent flung from the element at the points of different radii, the element having spiral grooves on the upper surface thereof for feeding the greatest quantities of reducing metal per unit of circumference to portions of the element of greatest radius, the amount of reducing agent fed from a given point being a direct function of the square of the distance between that point and the axis of the element.

6. Apparatus for producing titanium by reduction of a titanium compound dissolved in a fused salt bath, the apparatus comprising a reaction chamber for holding a fused salt bath, a titanium disc mounted above the surface of the fused salt bath, means for rotating the disc about an axis substantially normal to the fused salt bath so that the disc rotates in a plane substantially parallel References Cited in the file of this patent UNITED STATES PATENTS Butcher et al. June 4, 1867 Von Pazsiczky Sept. 1, 1942 Truthe Dec. 8, 1942 Landgraf Aug. 22, 1944 Hancox et a1 Mar. 13, 1951 Jordan Aug. 4, 1953

Claims (1)

1. APPARATUS FOR PRODUCING CRYSTALLINE REFACTORY METAL BY REDUCTION OF A REFRACTORY METAL COMPOUND DISSOLVED IN A FUSED SALT BATH, THE APPARATUS COMPRISING A REACTION CHAMBER FOR HOLDING A FUSED SALT BATH, A METALLIC ELEMENT MOUNTED ABOVE THE SURFACE OF THE FUSED SALT BATH, MEANS FOR ROTATING THE ELEMENT ABOUT AN AXIS SUBSTANTIALLY NORMAL TO THE FUSED SALT BATH SO THAT THE ELEMENT ROTATES IN A PLANE SUBSTANTIALLY PARALLEL TO THE FUSED SALT BATH SURFACE, AND MEANS FOR FEEDING A LIQUID METAL REDUCING AGENT TO THE ELEMENT NEAR THE AXIS OF ROTATION THEREOF, THE CIRCUMFERENCE OF THE ELEMENT VARYING FROM A CIRCLE TO PROVIDE PORTIONS OF DIFFERENT RADII CAPABLE OF IMPARTING DIFFERENT HORIZONTAL VELOCITIES TO DROPLETS OF REDUCING AGENT FLUNG FROM THE ELEMENT AT THE POINT OF DIFFERENT RADII.

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