US2837811A - Electrode composition - Google Patents

Description

ELECTRODE COMPOSITION Gerald G. Hatch, Chicago, Ill., assignor to Kennecott Copper Corporation, New York, N. Y.

Original application May 31, 1950, Serial No. 165,346,

now Patent No. 2,676,882, dated April 27, 1954. Divided and this application June 23, 1953, Serial No. 371,092

1 Claim. (Cl. 29-191.2)

The present invention is particularly adapted to a method for the recovering of elementaltitanium from a reaction mixture produced in accordance with the method disclosed in Glasser and Hampel application Serial No. 90,954, entitled, Method for the Production of Titanium, and assigned to the same assignee as the present application. It will be realized, however, that the features of the invention may be utilized in connection with the recovery of refractory metals other than titanium, such as, for example, zirconium, beryllium, chromium, cobalt, manganese, molybdneum, nickel, platinum, silicon, tungsten, and the like, and that it will also be applicable to the recovery of refractory metals from admixture with salts of reducing metals such as sodium, potassium, lithium, calcium, strontium, barium, and magnesium.

Briefly, the above-described process consists in reacting liquid titanium tetrachloride with an alkali metal amalgam such as sodium amalgam to form a reaction product containing powdery titanium particles, sodium chloride, to- Vgether with any sub-halides to titanium produced in the reaction, as well as residual mercury. Since the sodium content of the original amalgam is generally quite low and since an excess of sodium in the amalgam with respect toV titanium tetrachloride is used, large quantities of mercury appear in the reaction product. The removal of such large quantities of mercury is a considerable task, since the mercury adheres readily to the reaction product. While the mercury can be removed by distillation or gravity filtration, these are very time-consuming and expensive operations.

With the foregoing in mind, an object .of the present invention is to provide a convenient method for the recovery of refractory metal from admixture with compounds having lower fusing points than the metal.

Yet another object of the present invention is to provide a compressed mixture of titanium metal and sodium chloride crystals from which titanium metal can be readily recovered, and which is stable in air, water, and other reagents. n

Other objects and features of the present invention will be apparent from the following description and the appended claim.

The method of the present invention generally consists ;o,f compressing the reaction product from the amalgam reaction, which will contain powdery titanium,` mercury, and sodium chloride under elevated temperatures to thereby squeeze out all or a major portion of the mercury present and also substantial quantities of the sodium chloride. This compression is eifected in the presence of an inert gas such as argon, helium, neon, krypton, and the like, under substantially atmospheric pressures. The reaction mixture is compressed to a coherent shape preferably containing at least 35% by weight titanium with the balance being essentially sodium chloride. This mixture can then be treated for the recovery of metallic z method described in my copending application Serial No. 165,347, now abandoned, filed concurrently herewith. Another method for the recovery of titanium from such a mixture which may be used is the vacuum distillation of the sodium chloride present. In addition, the rod can be conveniently melted in an induction furnace where the sodium chloride is removed by volatilization.

The advantages of the present invention are quite substantial. For one, the compression of the titanium into coherent form directly upon removal from the reaction zone removes the tendency for the titanium to become contaminated, since the Vcrystals of Vtitanium are compressed into a much less reactive form Vthan the submicroscopic particles which are produced by the reaction. Further, vacuum conditions are not essential in the 'removal'of mercury and sodium chloride according to Vthe present invention, but such removal may be effected in the presence of an inert gas at substantially atmospheric pressures. The process also has the advantage of flexibility in that it can be made part of a continuous or semicontinuous process by using the process of the present in,

has been made to the use of gravity type filters or distil- Y lation to remove most of the mercury prior to the treatment of the reactionmass for the removal of sodium chloride.k By removing the sodium chloride in accordance with the present invention, a considerable amount of heat is saved, since the heat required is only sufficient to melt the sodium chloride and not necessarily to vaporize it.

Another advantage which can be realized by the practice of the present invention is the convenience by which titanium alloys can be prepared. Thus, the alloying elements may beradded to the reaction mass prior to the compression step before the removal ofv mercury and sodium chloride, and the alloying elements are carried through the compression step into the final compressed mixture. Y p

A very important advantage arising from the present invention is that the titanium rod or pencil which is produced as a result of the compression contains agglom,y

. erated particles of titanium which are sul'liciently large titanium in any one of a number of manners. For ex- 7 ample, the mixture may be introduced into an arc melting furnace as a consumable electrode according to the to be stable upon exposure to air. Thus, the compressed' product may be stored for indefinite periods priorto further treatment.

While the foregoing description of the process wa's con-l cerned with the recovery of elemental titanium by a reaction involving reduction with a sodium amalgam, itV

will be appreciated that the same process can be applied to the recovery of other reactive metals, such as zirconium, which, in finely divided form, are extremely reactive to air, oxygen, nitrogen and aqueous liquids. mentioned previously, the process is also applicable to the recovery of titanium'and other refractory metals from Y Figure 1 is a cross-sectional view of y 'an-,apparatusde-fv signed Vto carry out the process of the present invention; and

Figure 2 is a fragmentary cross-sectional view of the lower portion of the apparatus showing the conditioner thebeginning of the compression operation,

As shown on the drawing:

Patented June 1Q, 1958 Y Another 'type is illustrated in the- Reference numeral denotes generally a casing consisting of an outer jacket 11 and an inner casing 12. The inner casing 12 has aninlet 13 formed therein for receiving the products from the reaction. zone which will normally comprise a large percentage of mercury, sodium chloride, and titanium metal in the form of a very line powder. Below the inlet 13, there is a cylindrical reservoir portion 14 having a relatively large number of perorations 15 therearound. For the sake of better illustra-l tion, the size of the perforations 15 has been exaggerated in the drawings, as the actual size of such pcrforations will normally be less than abouti/s of an'inch in diameter.

The inner casing' 12 below the reservoir portion 14 is formed with a tapered perforatedV wall lportion 16. The tapered wall portion 16 terminates in a restricted orifice 17 having a perforated conduit 13 depending therefrom. A batiie 19 is disposed between the tapered wall portion 16 and the outer jacket 11, and a second battle 20 between the conduit 13 and the jacket 11 are provided `for purposes which will be hereinafter described.

At the base of the outer jacket 11 andthe perforated conduit 18, is a cylindrical member 21 having a base ange 22 which' can be secured to the inlet of an are melting furnace where the compressed product is to be used as a consumable electrode in an arc melting process. An inlet 23 and an outlet 24 are provided along the cylinder 21 for circulating an. inert gas such as argon and the like Within the cylinder 21. A cooling coil 25 around the base of the cylinder 21 is provided to aid in freezing the compressed mixture after the removal of some of its sodium chloride content.

The top of the casing 12is provided with a peripheral flange portion 26 to which is secured ay closure member 27, asV by means of bolts 28. The. closure member 27 is provided with an inlet 29 for introducing an inert gas of the type described within the casing 12. A 'boss 30 on the' closure member 27 has an axial bore therethrough for slidably receiving a shaft' 31 carrying a plunger 32. The diameter of the plunger 32 is only slightly smaller than the interior diameter of the casing 12 so that the plunger 32 is freely reciprocable within the reservoir portion 14 of the assembly, and permits the inert gas from the inlet 29 to ow past the plunger 32.

The casing 16 and its adjuncts are disposed within a furnace 35 having a plurality of spaced heating elements 36 therein which control the temperature of the furnace. Provision should be made for independently controlling the temperatures attained by the various heating elements since it is desirable to operate the upper section of the furnace at a substantially lower temperature than the bottom of the furnace.

The operation of the apparatus shown in Figure 1 will now be described. The furnace temperatures are adjusted so that the temperature at the tapered wall portion 16' of the casing is below the melting point lof sodium chloride, and normally within the range from room temperature of l500 F. and preferably from 600 to 1500 F. The lower portion of the furnace is operated at a somewhat higher temperature, so that the temperature below the restricted orifice 17 is above the melting point of sodium chloride, and, where the system is operated under an atmospheric pressure of argon, this temperature will be in the range from about 1500 to 1800 F. However, these ranges of temperatures may overlap, as long as a suticiently long section o f the apparatus is operated at a temperature above the melting point of the salt to be removed.

A supply of reaction products ,from the amalgam reaction zone is introduced into the casing through the inlet 13 Vand is compressed by downward strokes of the plunger 32 against the tapered side wall 16 and assault through the orifice 17 of the inner casing 14. The tapered side wall 16 effectively magnies the compressive force exerted by the plunger 32 so that `most of the mercury is removed before the reaction mixturepasses `through 4 .t the orice 17. The mercury is removed by gravity flow through a downwardly inclined discharge pipe 40 formed in the outer jacket 11 and extending through the furnace 35.

The mixture entering the restricted orifice 17 is free or substantially free from mercury, and consists essentially of titanium crystals and sodium chloride. Since the temperature occurring below the orifice 17 is above the rneltingpointV of sodium. chloride, further compression of the mixture at these temperatures causes the sodium chloride toflow through the perforations in the conduit 18 fand accurnmulate on the balile 2|),` from which' it', may' be drained through a discharge conduit 41' in communication therewith. Sodium chloride is remarkably uid at temperatures even slightly above its melting point, so that a large amount of the sodium chloride present can be removed through the compression operation. lt will be understood that the process can be carried ,out to remove practically all of the sodium chloride, but this is not usually the most economical mode of procedure.

'In normal instances, enough sodium chloride will be removed during the compression to form a mixture of titanium and sodium chloride having at least 35% by weight titanium. A suitable rod for use as a consumable electrode in an arc melting process is prepared by carrying out the compression of the mixture until a compact containing about titanium and 25% sodium chloride remains.

The compressed product, as illustrated in Figure 1, is in the form of a self-sustaining rod 42. The. compression 0f the titanium crystals at the elevated tem? peratures used for removing sodium chloride vis suicient to agglomerate very tine particles of titanium metal originally present into a stable form so that the finished rod 42 is stable in air may be stored for extended periods prior to Vrecovery of metallic titanium therefrom. To facilitate the freezing of the extruded mixture o f titanium and sodium chloride crystals after the removal of substantial portions of the sodium chloride, the cooling coils 25 are provided with a circulating cooling medium suchas water.

"The apparatus shown in'Figure l is show n `in the coursel of a continuous extrusion operation wherethe rod- 42 is continuously fed through the flange 22 of the cylinder 21'. To initiate the original compression, an anvil 45 (Fig. 2) having a base portion 46 secured to the ange 22 by meansV of bolts 47 is inserted within the cylinder 2.1. The anvil 45 has a tapered upper end portion 48 arranged to be snugly seated within the `bore of the cylinder 21. The anvil 45 is maintained in this position until a sufficient amount of the reaction. product has been introduced into. the system and the plunger 32 has compressed the mass until the compressed mixtureV at the `base of the .conduit 18 is suiciently rigid to form a self-sustaining structure. Thereupon, the anvil` 45 is removed Vand the extrusion may be operatedV continuously as illustrated ,inFigure l.

The reduction in volume of the reaction product within the apparatus Iis quite substantial, being on the order of 20 times or more.

While the present invention hasV been described primarily with respect tojtreating a reaction product conf,

may .be ejected without departingfrom the scope of theV no vel ,concepts .of the present invention.

I claim as my invention:

A consumable electrode comprising a rod of a compressed mixture of about 75% by weight of titanium particles and about 25% by weight of sodium chloride, the titanium particles being suiciently large to be stable toward air.

References Cited in the le of this patent UNITED STATES PATENTS 2,205,854 Kroll June 25, 1940 2,522,679 Kroll Sept. 19, 1950 2,564,337 Maddex Aug'. 14, 1951 2,621,121 Winter Dec. 9,' 1952 OTHER REFERENCES Preparation and Properties of Ductile Titanium, R. S.

Dean et al. pages 1-13, Metals Technology, Technical Publication 1961, February 1946 by American Institute of 5 Mining and Metallurgical Engineers.

U. S. Air Force Project Rand, Titanium & Titanium- Base Alloys, published Mar. 13, 1949 by the Rand Corp. Santa Monica, Calif., pages 52-58 inclusive.

Journal of Metals, April 1950. Ductile Titanium,

10 Vpages 634-64O inclusive by Maddex et al., page 640 relied upon. 75-84.

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