US2574268A - Manufacture of uranium tetrachloride - Google Patents

Description

Nov. 6, 1951 M. D. KAMEN MANUFACTURE OF URANIUM TETRACHLORIDE Filed Nov. 30, 1944 INVENTOR. (ll/4X77 0. m/m /v Patented Nov. 6, 1951 MANUFACTURE OF URANIUM 'TETRACHLORIDE Martin D. .Kamen, .Berkeley, Calif., assignor to V H g the United :Statesof America as represented by the United States Atomic Energy Commission Application November 30, 1944, Serial N 0. 566,009

. S-Claims.

4 This invention -re1atesl'to the manufactureof uranium tetrachloride and more particularly to a. process using trichloroacetylchloride and an oxide of uranium for the manufacture of uranitetrachloride.

It is an object of this invention to provide an improved process of producing uranium tetrachloride or high chemical purity and in crystalline form. I

Another object of the invention is to provide animproved trichloroacetylchloride and uranium oxideprocess of producing uranium tetrachloride inwh-ich the product is of uniform purity and *si-dereactions productive of other uranium chloridesand other objectionable compounds are minimized.

Another object of the invention is to provide 'an improved process of producing uranium tetra- V chloride which involves a reaction of trichloroacetylchloride vapor with an oxide of uranium.

A general advance in the art and other objects which will appear hereinafter are also contemplated.

It has now been found that uranium tetrachloride can be prepared in high yield and high purity by maintaining a continuous flow of triel-iloroacetylchloride over a charge of uranium oxide (U02, U03, or U308) heated to a temperature'within therange of 135 to 225 0. and as "near 180 C. as practicable, the pressure being substantially atmospheric. It has also been {found that an apparatus particularly suited to parryout this procedure comprises vaporizing and reaction chambers so connected and arranged that the trichloroacetylchloride vapors may be forced by gravity from the vaporizing chamber into the reaction chamber and the gaseous products formed in the reaction chamber are forced to exit through the vaporizing chamber.

How the foregoing objects and related ends are accomplished will be apparent from the following xposition; in which are disclosed the principles, the organization, and divers embodiments of the invention including the best mode contemplated iorcarrying out the same, all of which is amplified by the accompanying drawing in which suitable apparatus is shown diagrammatically. Proportions of reagents are specified as parts by weight throughout the written description.

Referring now to the single sheet of the drawing, there is shown a reaction vessel 3 connected 5110 .a condenser L. which is in turn connected to asupplyreservoir 2. An inner gas l-ine'C extends through the condenser and into the reaction vesgel. The reaction vessel is shaped somewhat like an hourglass and comprises a reaction chamber A and a vaporizing chamber B. These chambers are supported on sand bath heaters 5 and v6, respectively. The sand heater 5 is supported on a bracket 1 and the sand heater 6 is supported on a bracket 8. Both brackets are secured to the upright of a stand 9 which rests on the surface ll. At the other end of the apparatus the upright of a stand [2 s pports a bracket 13 which in turn supports bracket M which in its turn, through a clamp l5, supports the ,elevated end of the condenser at which end is vent .4. The upright of the stand I2 alsosupports a bracket 7 Hi to which is secured a clamp H which in turn supports the reservoir 2. Usually the reservoir 2 is graduated and has a gravity feed valve H3 whereby the rate at which the liquid reactant trichloroacetylchloride is being utilized can be regulated. A container for an inert .gas under pressure (not shown) is connected at the upper end of the line C. The outer jacket E of the condenser has the usual inlet I9 and outlet 2| for a cooling fluid.

In operation the reaction chamber A is charged with uranium dioxide and the reaction vessel 3 connected to the condenser L. A gentle stream of inert gas such as nitrogen is flowed into the reaction chamber A through the line C to sweep out the air. The flow of inert gas continues throughout the reaction during which time it serves to sweep out by-product gases and. excess trichloroacetylchloride vapor. Heat is then applied to the reaction chamber A to raise .the temperature of the uranium oxide to 180 C. and said temperature is maintained while a flow of trichloroacetylchloride is started through the valve 18. This trichloroacetylchloride collects in the vaporizing vessel B. After a pool of the desired size has collected, heat is applied and the addition of trichloroacetylchloride from the reservoir 2 regulated to keep the liquid level in vessel B substantially constant. Upon the application of heat to the vaporizing chamber B some of the trichloroacetylchloride vapor that is evolved enters the condenser L and is refluxed. Another portion of the vapor flows by gravity into the reaction chamber where it reacts with the uranium dioxide, usually forming carbon monoxide, carbon dioxide, phosgene and chlorine. These gases are swept up into the condenser along with some trichloroacetylchloride vapor by means of the nitrogen entering through the line 0. Some of the phosgene is dissolved in the trichloroacetylchloride and carried back into the reaction chamber where it reacts with the wa :dioxide, or in vacuum.

iii'u'm dioxide. The gases which are iiot condensed in the condenser are vented through the line 4, preferably into a suitable scrubber which may be of conventional design and operation.

During the process additional trichloroacetyh chloride is supplied as it is consumed in the reaction witli'tliecharge of uranium oxide and the process iscontinued until all the charge of the uranium oxide has been converted to U014. At this time, i. e. when the reaction of the charge of uranium oxide is complete, the evolution-of reaction gases ceases, thereby providing a, readyf;

indication of the completion of the process.

In carrying out the present p oce s involving" uranium dioxide in the preduc'ti'on of ranium tetrachloride the reaction temperature should be maintained as near 180 C. as practicahhowever;

of this invention may be made without departing from the principle, breadth and spirit thereof and it is to be understood therefore that this invention is not limited to the specific embodiments thereof except as encompassed in the claims.

What is claimed is:

1; A proce'ss Qf producingurahium' tetrachloride comprising passingtrichloroacetylchloride vapors over an oxide of uranium maintained at a temperature within the range of 135 C. to 225 C., and.,1 ecoyering the uranium tetrachloride.

"' 2. ;Tlie process of producing uranium tetraclno- V ride comprising reacting uranium trioxide with tricli'loroacetylchloride vapor at a reaction temfper"ature wit the range of 135 C. to 225 C. in which the trichloroacetylchloride vapor is passed continuously over. the reaction mass, and recovsatisfactory results may be obtained in the range v of 135 to 225 C.

Substantially atmospheric pressure in the reaction zone is preferred, although elevated'or reduced pressures-are not objectionable and" small pressure variations do not materially affect 'the yields or purity of the product. 1

' The reaction is usually complete in less than five hours, the time depending to some extent on the crystalline form and particle size of the raw material, the temperature of the reaction," and the size of the charge. A reaction time of from two to five hours'has been found suitable. Trichloroacetylchloride of ordinary commercial purity is satisfactory for thereaction'. The process "maybe carriedout in glass or metal apparatus.

inert gases other than nitrogen may b i d butin the case of materials like illuminating gas some pyrolysis may occur.

-;The present invention is particularly useful in the treatment of uranium trioxide since itprovides a method for obtaining uranium tetrachloride instead ofthe pentachloride normally obtained. w

After the uranium tetrachloride hasbeen produced it may be removed from the reaction chamber in any desired manner, such as'byremoving the reaction chamber from theremainder of the apparatus and pouring the crystalline product therefrom. It should be" transferred to a dry container and maintained in storage under environment of a dry inert gas such as'carbon It may be noted that the uranium tetrachloride may frequently be associated with appreciable Quantities of uranium pentachloride formed during the course of the main'reaction; Ihese two chlorides may,vif desired, be separated ingan'y suitable manner, such as by extraction with a selective 'solvent for one of them. Carbon tetrachloride is an example of a suitable solvent for this purpose, since it has a preferential solvent action towards the pentachloride. Any non-volatile im purities such as uranium oxychloride or unrev acted uranium oxide still remaining in admixture with the uranium tetrachloride maybe separated, if desired, by a step of sublimation wherein the desired tetrachloride is sublimed away from the associated non-volatile impurities.

The uranium tetrachloride produced 'in accordance with the present invention hasa crystal size and structure especialy suitable for sublimation or vaporization'in vacuum apparatus. Its form allows it to be readily outgassed and there is little tendency for it'to be transported as a dust while being processed in region of reduced pressure.

Many' apparently widely different embodiments 152, pages 87-89.

544 and545,1917.' I

ering the uranium tetrachloride.

3.-Th'e"process comprising reacting trichloroacetylchloride vapor with uranium dioxide at a temperature of about=180 C. to produce uranium tetrachloride,: and recovering, the uranium tetra- Ch10ride.t=:=' r r; 4. The process of producing uranium tetrachloride containing some uranium pentachloride from an oxide of uranium comprising P reacting said oxide with the vapors of;trichloroacetylchloride at an elevated temperature of the orderof 180.- C. for a period of time in the range of two to five hours, andrecovering-r the uranium tetrachloride.

.and recovering said uranium tetrachloride.

8. The processcomprising, reacting trichloroacetyl chloride vapor with an oxide of uranium selectedjfrom the group consisting of UO2,'-U O3 and U308 at a reaction temperature of about.180

C. and in the presenceof an inert gas while at atmospheric pressure to produce uranium tetrachloride of :high quality-and having a crystal and form suitable for processing in'an evacuated system.

W l VM'A'RTIN D. REFERENCES CITE-D,

The following references are of recordin the file. of this patent:- 1-

-A General Method of Preparing Anhydrous Chloridesed. Chauvenet'Compt. rend'., volume (Chemical Abstracts, volume 5, pa e 1036.) 1

Roscoe, Journal of the Chemical Society,'New

Sen, volume 12, pages 933-935 (1874).

'Camboulives, Comptes Renders, volume 150,

pages 175-177 (1910). Crudes, Chemical} Abstracts, volume 11 pages Mellor, Comprehensive Treatise on Inorganic and Theoretical Chemistry, volume 12; pages v and a1 (1932). Published by Longmanaor and Company Londoni e j f if

Claims (1)

1. A PROCESS OF PRODUCING URANIUM TETRACHLORIDE COMPRISING PASSING TRICHLOROACETHYLCHLORIDE VAPORS OVER AN OXIDE OF URANIUM MAINTAINED AT

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