US2858196A - Extraction apparatus - Google Patents

Description

1958 A. E; BALLA'RD ETAL 2,858,195

EXTRACTION APPARATUS FiledSept. 18, 1945 I IN V EN TORS 425622 15 Bai/a'rur 5749720771.

United States Patent Ofilice 2,858,196 Patented Oct. 28, 1958 EXTRACTION APPARATUS Albert E. Ballard and Harlow R. Brigham, Oak Ridge, Tenn., assignors to the United States of America as represented by the United States Atomic Energy Commission Application September 18, 1945, Serial No. 617,127

1 Claim. (Cl. 23-267) This invention relates to an apparatus for contacting solvents with materials either liquid-liquid phase or liquid-solid phase contact. More particularly, this invention concerns an apparatus whereby relatively volatile solvents may be contacted with volatile or non-volatile materials without certain attendant hazards. In the chemical industry there are many instances Where it is desired to contact a solvent comprising a relatively volatile liquid with a solution, suspension or slurry of the materials to be treated with the solvent. One such type of process is described in detail in the copending application in the name of Albert E. Ballard, one of the herein-named inventors, Ser. No. 32,832, filed June 14, 1948, now U. S. Letters Patent No. 2,758,007, issued August 7, 1956. As therein described a process is proposed which includes the contacting of certain chemical materials With an ether solvent. While this may be accomplished, as described in said companion application, by means of columns and other equipment containing few or no moving parts, in some instances in order to save space and for other purposes a different type of apparatus may be desired.

In the handling of volatile liquids, such as volatile ether solvents, or in other instances of processes using various hydrocarbons which are inflammable and which may have a low flash point, there may be attendant dangers if conventional equipment is used with an ordinary agitator therein. For example, the rotating shaft in an ordinary agitator might under some circumstances in rotating at high speed generate considerable frictional heat which would be conducted through the metal parts of the associated tanks thereby heating up the volatile solvent. If the heat generation is sufliciently great, ignition may occur and fires or explosions may be caused thereby.

In the apparatus of the present invention we provided equipment whereby relatively volatile, inflammable solvents may be employed in chemical processes requiring and utilizing vigorous agitation by a mechanical agitator, in a considerably safer and more convenient manner than heretofore accomplishable.

This invention has for one object to provide an improved apparatus adapted for contacting of a solvent With materials to be treated therewith accompanied by vigorous agitation.

Another object is to provide an improved extraction apparatus which includes at least one mechanical agitator associated therewith.

Still another object is to provide an apparatus of the class described in which the agitating equipment may be operated at high speed without attendant danger from overheating.

A still further object is to provide an extraction apparatus of the class indicated wherein access to the interior of the apparatus may be obtained without disturbing the agitator and inlet pipes as well as other parts.

Still another object is to provide an apparatus particularly useful for extracting materials containing uranium compounds by means of a relatively volatile solvent such as a lower aliphatic ether.

Other objects will appear hereinafter.

We have found that a suitable apparatus for handling relatively volatile liquids under the conditions indicated may be constructed comprising a tank member, and a closure member covering the tank and adapted to be securely attached to an external support. The closure member is provided with a plurality of inlets and a substantially rigidly mounted motor-driven agitator. This agitator member is connected from the driving motor into the interior of the tank through a gland adapted to be cooled with inert gas thereby eliminating possible hazard due to friction-al heat. The closure member, as arranged in the present invention, serves to function as an interposed shield between the driving motor and the interior of the tank. Also the closure member is arranged so that the tank member may be removed from this closure member without materially disturbing the closure member which, as described, carries the motor driven agitator and other parts.

For a more complete understanding of the present invention, reference will be made to the attached drawing forming a part of the present application.

Fig. 1 is a side elevation view of the apparatus, which view is largely in section. Fig. 2 is a sectional view showing in detail the construction of the: cooled packing gland associated with the agitator shaft.

Referring now to Fig. l, the apparatus is comprised of the tank 1. The tank has a tapered bottom 2 for facilitating the drawing out of any residues therefrom, for example, through conduits 3 and 4. Suitable shutoff valves (not shown) may, of course, be provided in conduits 3 and 4. The tank 1 is inclosed in a temperature control jacket 5 of conventional construction through which may be circulated heating or cooling fluid in the usual manner as may be required.

In accordance with the present invention, the tank portion is bolted by bolts 6 to the closure member 7. The cover member 7 is, in turn, preferably integral with the wall bracket member 8 adapted to be secured to some suitable support.

The closure member 7 is provided with a number of inlet conduits or comparable openings for the insertion or attachment of pipes and the like designated 9, 10, and 11, the member 10, for example, being a connection to an explosion vent. Suitable conduits for supplying material into the apparatus or for Withdrawing materials may be inserted through or connected to these various parts as may be required. For example, conduits 22 and 23 may beprovided for drawing off ether and water, the sludge being removed through conduits 3 and 4. The exact number of such conduits is not a limitation on the present invention, the foregoing merely being illustrative.

An agitator shaft 12 supported by packing gland 13 likewise passes through closure member 7. All of the aforementioned parts may be securely mounted inasmuch as access may be had to tank 1 by disconnecting pipes at 3 and 4, unbolting bolts 6 and dropping down the tank.

Referring now to Fig. 2, the agitator shaft is sealed in a movable manner as may be observed by reference to this figure. The agitator shaft 12 is driven by moto-r 14 which rotates the shaft 12 in the absorbent packing 16. The shaft is also packed with leather, asbestos and the like packing 17. A number of holes or open ings designated 18 are provided for permitting the flow around the shaft of nitrogen or other inert gas thereby providing a cooled seal. A small pipe (not shown) may be attached at 19 for gas supply. That is, should frictional heat develop from the rotation of the shaft 12, this heat would be removed by the inert gas forced in through 19runder slightpositive pressure, thereby preventing-ignition of the ether fumes. A plurality of packing nuts of usual construction are provided, namely members 20 and 21, for applying pressure on the aforementioned packing.

In the operation of the apparatus, the material-to be extracted, such as a solution containing a uranium salt as, for example, U nitrate solution, is introduced into the rapparatus. Solvent may be introduced through the opening 9, for example, and a salting out agent, such as coppernitrate, through opening 11, and the materials mixed together by means of the agitator rotated at high speed. After the extraction, the various phases within the tank 1 may be-permitted to settle, and the different phases withdrawn through the several conduits. That is, atthe end of the settling period-any sludge and some of the aqueous liquid may be drawn off through conduits 3 and 4. Then the aqueous acidic layer stripped of -U may be withdrawn through conduit 22 by pumping, aspiration or in some other manner, there-by allowing the ether v(extract layer containing the U) to fall to the lower end of conduit 23. Then the extract may be withdrawn through conduit 23. Or the removal of any sludge may be delayed to the end of the process. At the completion of the process, the tank may be removed by unbolting it at 6 and access gained to the interior, if this is desired for cleaning or other purpose, without disturbing the agitator and other parts.

In general, in the extraction of uranium materials with a relatively volatile solvent such as ethyl ether or similar solvents, several units such as above described are connected together. That is, the ether phase from one extraction step is transferred to another unit and agitated with water, for example, for transferring the U materials from the ether extract to an aqueous phase. The aqueous phase then containing the U component may be conductedto precipitation where U peroxide is thrown down. Since the proportions of solvent, the use of salting out agents, precipitation details and the like detailsare described in said companion case referred to above, such description is not repeated herein. It appears sufficient to point out herein that we have provided an apparatus whereby a volatile solvent may be vigorously contacted with material to be treated with the solvent with a minimum of hazard from possible heat generation due to rapid rotation of the agitating mechanism employed for bringing about the aforementioned vigorous contact. Even though a volatile inflammable solvent is employed, by means of the cooled packing gland, danger from overheating due to the high speed rotating shaft is minimized. It has been found that by vigorously contacting, for example ethyl ether with uranium nitrate solutions,v that the valuable U may be very efiiciently extracted into the ether solvent away from the undesired materials which also may be present along with the U. As already indicated, copper nitrate and other components may be included for facilitating this extraction as'described in the companion application. The present apparatus may be advantageously employed in such'extraction processes under circumstances where column operation as described in the companion case is undesired or Where space for such apparatusis .not available.

The apparatus parts herein described may be constructed of the usual materials. For example, tank member 1 may be made of any of the various stainless steels which resist nitric acid as may be the agitator shaft and impeller. The particular design of the shaft and impeller shown is exemplatory and other designs of impellers which give thorough mixing may be used. While, in most instances, sufficient inert gas escapes between the shaft and the packing and ultimately out through vent 10 with the other fumes, thereby giving adequate-inert gas flow for heat adsorption, if desired, the gland may be provided with a separate exhaust port for the inert gas forv obtaining greater flow. Other changes and additions will be apparent from the description herein.

It is to be understood that all matters contained in the above'description and examples are illustrative only anddo not-limit the scope of this invention as itis intended to claim the invention as broadly as possiblezin view of the prior art.

\Veclairn:

Inan apparatus for carrying out a chemical extraction process, in combination, means forming a tank, supporting means for the tank comprising a fixed supporting member having an integral portion forming a closure member for the top of the tank and to which the tank is detachably secured, said closure member having therein a plurality of fittings providing for communication intothe interior of the tank, said closure member having mounted'thereon amotor driven agitator including a fluid cooled shaft seal and a shaft extending therethrough into the interior of the tank, said apparatus having the characteristic that the tank may be detached from theelosure member and removed without disturbing any connections to the fittings in the closure member and without disturbing the agitator.

References Cited in thefile of this patent UNITED-STATES PATENTS 686,059 Hart'shorn et al. -n Nov. 5, 1901 1,295,223 Smith Feb. 25,1919 1,733,724 Downs Oct. 29, 1929 2,366,669 Maude .a Jan. 2, 1945

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