LOS ALAMOS NATIONAL LABORATORY. PATENTS REPRESENTING LOS ALAMOS lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll fiEf RESEARCH USO05098682A [II] Patent Number: 5,098,682 Q “’”’’’-”: [45] Mar. 24,1992 - 1%0.6 Foropoulos, Jr. et al. Date of Patent: *42 [5-$] DEHYDRATION OFPLUTONIUMOR 4,859,441 8/1989 Lambard .. .... .... .... .... ..... 423/19 [AA NEPTUNIUM TRICHLORIDE HYDRATE OTHER PUBLICATIONS [75] Inventors: Jerry Foropoulos, Jr.; Larry R. Freeman et al., J. Inorg. IVucl. Chenr.) 7,224-227 (1958). Avens, both of Los Alamos; Eddie A. Cleveland, The Chemisfty of Plutonium, pp. 353-358, Trujillo, Espanola, all of N. Mex. Gordon and Breach Science Pub]. (1970) New York. [73] Assignee: The United States of America as Primmy Examirrer-Edward A. Miller represented by the United States Attorney, Agent, or Firm—Bruce H. Cottrel; Paul D. Department of Energy, Washington, Gaetjens; William R. Moser D.C. [57] ABSTRA~ [21] Appl. No.: 755,280 A process of preparing anhydrous actinide metal tri- [22] Filed: Sep. 5, 1991 chlorides of plutonium or neptunium W reacting an aqueous solution of an actinide metal trichloride se- [51] Int. ~.' .............................................~lG56/~ lected from the group consisting of plutonium trichlo- [52] U.S. Cl . ......................................423/25 l.423/l9. 423/250 ride or neptunium trichloride with a reducing agent capable of converting the actinide metal from an oxida- [58] Field of Search .......................... 423/250. 251.19 tion state of +4 to +3 in a resultant solution, evaporat- [56] References Cited ing essentially all the solvent from the resultant solution U.S. PATENT DOCUMENTS to yield an actinide trichloride hydrate material, dehy- drating the actinide trichloride hydrate material by 2,578,416 12/1951 Fried et al. ..........................423/250 heating the material in admixture with excess thionyl 2,859,097 11/1958 Davidson e! al. ...................423/251 chloride, and recovering anhydrous actinide trichloride 2,860,032 11/1958 Davidson elal ...................423/251 is provided. 2,860,948 11/1958 Fried ..................................... 423/19 3,700.710 10/1972 Mottuse~ al. ....................... 252/431 4,519,986 5/1985 Pastor e! al. .......................... 423/19 10 Claims, No Drawings 5,098,682 1 2 drate 10 .anhydrous plutonium trichloride, such a pro- DEHYDRATION OF PLUTONIUM OR cess beirig further applicable to trivalent neptunium NEPTUNIUM TRICHLORIDE HYDRATE trichloride as well. Accordingly, it is an object of this invention to pro- This invention is the result of a contract with the 5 vide a process of converting plutonium trichloride hy- Department of Energy (Contract No, W-7405 -ENG-36), drate to anhydrous plutonium trichloride. It is a further object of the invention to provide a FIELD OF THE INVENTION process of converting neptunium trichloride hydrate to anhydrous neptunium trichloride. The present invention relates to the field of actinide 10 SUMMARY OF THE INVENTION chemistry and particularly to the chemistry of phsto- nium and neptunium. To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, BACKGROUND OF THE INVENTION as embodied and broadly described herein, the present 15 invention provides a process of preparing anhydrous Anhydrous actinide trichlorides such as plutonium actinide metal trichlorides of plutonium or neptunium trichloride and neptunium trichloride are important by reacting an aqueous solution of an actinide metal starting materials for chemical synthesis. PI utonium trichloride selected from the group consisting of pluto- trichloride can be prepared by a number of methods nium trichloride or neptunium trichloride with a reduc- such as the reaction of either carbon tetrachloride or 20 ing agent capable of converting the actinide metal from phosgene with plutonium oxide, the reaction of either an oxidation state of +4 to + 3 in a resultant solution, hydrogen chloride or phosgene with plutonium oxalate, evaporating essentially all the solvent from the resultant the reaction of plutonium metal with chlorine, the reac- solution to yield an actinide tnchlonde hydrate mate- tion of plutonium hydride with hydrogen chloride, or rial, dehydrating the actinide trichloride hydrate mate- the reaction of a mixt.ure..of ammonium chloride and 25 rial by heating the material in admixture with excess liquid hydrogen chloride with plutonium oxide, While thionyl chloride, and recovering anhydrous actinide such reactions are all reasonably efficient in producing trichloride. In a preferred process, the thionyl chloride plutonium trichloride, they suffer from disadvantages admixed with the hydrate material is a liquid. such as poor waste minimization and greater radiation DETAILED DESCRIPTION exposures to personnel. In addition, when plutonium 30 oxide is used, itmust be initially prepared, usually by The present invention concerns the use of thionyl calcining an oxalate which itself is generally first pre- chloride in the dehydration of actinide trichloride hy- cipitated from an aqueous solution. Similarly, the use of drates wherein the actinide is plutonium or neptunium plutonium hydride or plutonium metal requires that the to yield the respective anh ydrous trichloride. metal be initially produced. In these cases, the end prod- 35 Aqueous solutions of plutonium trichloride and nep- uct of a first multi-step process is used to feed another tunium trichloride are readily preparedly by dissolution multi-step process. of plutonium compounds and neptunium compounds in One desirable route in the preparation of anhydrous hydrochloric acid. However, obtaining the anhydrous plutonium trichloride would be to use a solution of product from these solutions has generally proven diffi plutonium in hydrochloric acid. It is previously known 40 cult. that evaporation of such plutonium solutions can yield Thionyl chloride is the dehydrating agent used to plutonium chloride hydrate and that the anhydrous convert the particular hydrate to the anhydrous materi- product can then be obtained by heating the hydrate in als. Previously, it had been believed that the trivalent a stream of dry hydrogen chloride. While this method is plutonium and neptunium systems would not permit the useful, such a process is generally unsuitable for prepa- 45 thionyl chloride dehydration process to operate. The rations of the anhydrous product because of the quanti- thionyl chloride can be admixed with the particular ties of gas needed and the added difficulties of drying, hydrate material as either a gas or a liquid, preferably as recycling and/or scrubbing the hydrated HC1 by-pro- a liquid. As a gas, thionyl chloride may accomplish the duct. Moreover, attempts to obtain the anhydrous mate- dehydration of the plutonium chloride hydrate with rial directly from the aqueous solution simply by evapo- 50 slow heating, e.g., bypassing thionyl chloride vapor ration and further heating suffer from significant forma- over the solid plutonium chloride hydrate while heating tion of plutonium oxychloride occurs upon dehydra- at above about 8(Y C. One manner of contacting the tion. hydrate and the gaseous thionyl chloride is to distribute Thionyl chloride, SOC12, has long been known to the solid upon a porous fnt and pass the gas through and produce anhydrous chlorides from many metal hy- 55 around the solid hydrate material. By admixing the drates. It has also been used in organic chemistry as a thionyl chloride as a liquid in a liquid-solid slurry with coreactant to remove water from a reaction mixture. the hydrate material, the need for a large reactor vol- The use of thionyl chloride as a dehydrating agent for ume for gas drying and handling can be avoided. Fur- preparation of anhydrous inorganic chlorides is de- ther, the use of thionyl chloride in the present process of scribed by Freeman et al. in J. Inorg. Nucl. Chem., vol. 60 preparing the anhydrous product can reduce or mini- 7, pp.224-227 (1958). However, Freeman et al. report mize waste products and reduce overall radiation expo- that the process was not applicable to plutonium tri- sure to personnel. Excess thionyl chloride used in the chloride. This is in contrast to their work with other present process can be recycled with the only waste chlorides such as thorium, copper, magnesium, or iron, stream including sulfur dioxide and HCI which can be and numerous ianthanide metal chlorides. 65 easily scrubbed via reaction with soda lime. Sumrisinszly, the present inventors have now discov- In the present invention, actinide trichloride hydrate ered that th~onyl chloride can be used as a dehydrating material can be converted to the corresponding anhy- agent for the conversion of plutonium trichloride hy- drous material by heating the hydrate material in admix- 5.098.682 3 4 ture with thionyl chloride, said heating at temperatures attributable to water. Elemental analysis indicated and for time sufficient to dehydrate said hydrate mate- 66.77c Pu and 3 1.07c Cl with about I-2CZ impurities —_ rial. such as alkalis, alkaline earths and traces of silicon and In a general process of the present invention, an aque- iron. ous solution of plutonium trichloride or neptunium 5 Although the present invention has been described trichloride is reacted with a reducing agent capable of with reference to specific details, it is not intended that converting all of the respective actinide ions to the + 3 such details should be regarded as limitations tmon the oxidation state, i.e.,