US2892681A

US2892681A - Separation process for zirconium and compounds thereof

Info

Publication number: US2892681A
Application number: US112404A
Authority: US
Inventors: Howard W Crandall; John R Thomas
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-08-25
Filing date: 1949-08-25
Publication date: 1959-06-30
Anticipated expiration: 1976-06-30

Description

United States Patent Ofiice 2,892,681 Patented June 30, 1959 SEPARATION PROCESS FOR ZIRtIONIUM AND COMPOUNDS THEREGF Howard W. Crandall, Berkeley, Calif., and John R. Thomas, Silver Spring, Md., assiguors to the United States of America as represented by the United States Atomic Energy Commission No Drawing. Application August 25, 1949 Serial No. 112,404

22 Claims. (Cl. 23-88) This invention relates to compounds of zirconium and to a process for the separation of zirconium from aqueous solutions, and it more especially relates to the separation of zirconium from columbium, rare earths, yttrium and alkaline earth metals.

The present invention also relates to the extraction of zirconium from an organic solvent solution of a zirconium chelate compound.

During neutron irradiation of uranium there are produced in addition to the transuranic elements, Np and Pu, other elements of lower atomic weight, known as fission fragments. These radioactive fission fragments are composed of two distinct groups of elements, namely, a light element group and a heavy element group. The light element group contains elements having atomic numbers between about 35 and 46 and the heavier element group is composed of atomic numbers between about 51 and 60. The elements of both of these groups as originally produced, being considerably overmassed and undercharged, are highly unstable. By means of beta radiation they quickly transform themselves into' isotopes of other elements having longer half-lives. The fission fragments and the resulting decay products are collectively known as fission products.

The various radioactive fission products have halflives that range from a fraction of a second to thousands of years. Those having very short half-lives may be substantially eliminated by aging the neutron-irradiated material for a reasonable period of time before further processing. Those radioactive fission products having very long half-lives do not have a sufliciently intense radiation to endanger personnel protected by moderate shielding. On the other hand, the radioactive fission products that have half-lives ranging from a few days to a few years have dangerously intense radiations which cannot be eliminated by aging for practical storage periods. These fission products are chiefly radioactive isotopes of Sr, Y, Zr, Cb, Ru, Te, I, Cs, Ba, La, Ce, and Pr.

The material from the neutronic reactor contains a total amount of fission products that is rarely above 1% by weight of the uranium and usually substantially below this concentration, e.g., one part per thousand parts and even one part per million parts of uranium. In order to recover a particular fission product, it is necessary to separate it from large masses of uranium, from plutonium, and from other fission products. Various processes have been developed for separating uranium and plutonium from the fission products.

The zirconium isotope Zr is produced as one of the fission products. It is a fi-emitting isotope with a halflife of 65 days and thus disintegrates to Cb which is also p-emitting and has a half life of 35 days. It disintegrates to M a nonradioactive isotope which occurs in natural molybdenum in the amount of about 16% For use in research including medical and metallurgical research the radioactive isotopes Zr and Cb in pure form are desired.

Zirconium occurs in various ores, principally as ZrO in baddeleyite and as ZrSiO which is called zircon. By various methods aqueous solutions of zirconium salts are obtained from these ores.

It is an object of the present invention to provide new compounds of zirconium A second object of this invention is to separate Zirconium from its aqueous solutions.

A third object of the present invention is to separate zirconium from aqueous solutions containing salts of zirconium and other fission products of uranium.

Another object of this invention is to separate zirconium from an aqueous solution also containing a salt of a rare earth.

A further object of the present invention is to provide a process for the separation of zirconium from an aqueous solution also containing a yttrium salt.

Still a further object of this invention is to separate zirconium from an aqueous solution also containing an alkaline earth salt. a

-It is also an object of this invention to provide a means for separating zirconium from an organic solvent solution and especially from anorganic solvent solution ob tained in the extraction of zirconium as a chelate from aqueous solutions.

Other objects of this invention will 'be apparent from the description which follows:

We have found that a suitable separation of zirconium from an acidic aqueous solution of a tetravalent zirconium salt can be obtained by contacting the aqueous solution with a certain type of chelating agent alone or as an organic solvent solution to form a zirconium chelate compound. When the organic solvent is present the zirconium chelate compound is extracted; otherwise, it is separated by filtration or other suitable means.

The chelating agent of the present invention is a fluori nated B-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl, and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine. Of course, the R group may contain various substituents such as halogen groups and nitro groups. It is preferred that R and R both be fluorine atoms and examples of such a class of diketones are:

Tnifluoroacetylacetone CHr-C-CHg-F-O F;

Propionyltrifluoroacetone Isovaleryltrifluoro acetone Heptanoylu'ifiuoroacetone Benzoyltrifluoroacetone p-Fluorobenzoyltrifiuoroacetone p-Phenylbenzoyltrifluoroacetone p-Ethylbenzoyltrifiuoroacetone Examples of suitable fluorinated p-diketones containing less than three fluorine atoms are:

Difiuoroacetylacetone The efficiency of chelation-extraction is not the same for all. 2-thenoyltrifluoroacetone, benzoyltrifluoroacetone and trifluoroacetylacetone are preferred fluorinated fl-diketones to be used in the process of the present invention.

The organic solvent for the present invention is a substantially water-immiscible organic compound which is liquid at the temperature of carrying out the process. Examples of siutable types of organic solvents are aromatic hydrocarbons, chlorinated aromatic hydrocarbons, chlorinated parafiinic hydrocarbons and aliphatic ketones. Specific examples are benzene, toluene, chlorobenzene, hexafiuoroxylene, chloroform, carbon tetrachloride, trichloroethylene and methyl isobutyl ketone (also known as hexone). Benzene, toluene, hexafluoroxylene and hexone are the preferred solvents.

The acid present in the aqueous solution is a strong inorganic acid. The acid concentration is at least 0.001 N and preferably at least 0.1 N. It has been found possible to chelate-extract zirconium by the process of the present invention from aqueous solutions containing a strong inorganic acid in a concentration as high as 12 N by utilizing a higher concentration of the fluoriuated p-diketone as will be seen from data presented below. Examples of strong inorganic acids that are present in the aqueous solution from which zirconium is to be separated are as follows: nitric acid, hydrochloric acid, perchloric acid, and sulfuric acid. Nitric acid and hydrochloric acid are the preferred acids. The preferred acid concentration is between 0.1 and 2 N, especially when using the process to separate zirconium from colum'bium, rare earths, yttrium and alkaline earths.

The temperature at which the process is carried out may be varied considerably; for example, temperatures of 10 to 60 C. are satisfactory. The preferred temperature is room temperature.

The time of contact between the aqueous solution and the chelating agent or the aqueous solution of the chelating agent of this invention is dependent upon the temperature, the organic solvent, the specific chelating agent and numerous other factors including the efficiency of contacting the materials. While a wide range of contact time is suitable a time of at least 15 minutes is preferred.

When the chelating agent, namely, the fiuorinated B- diketone having the formula described above, is used with an organic solvent, the concentration of the chelating agent may be varied Widely. The concentration will depend upon the degree of extraction desired, upon the concentration of the zirconium salt in the initial aqueous solution, upon the nature and concenration of the strong inorganic acid, and upon the presence or absence of small amounts of water-soluble complexing agents for zirconium, that is, agents which complex zirconium to form water-soluble complexes. Some of the strong inorganic acids exhibit a mild complexing action upon zirconium thereby producing a lower distribution coefficient for zirconium for a particular hydrogen ion concentration as compared with the coefficient using a noncomplexing strong inorganic acid like perchloric acid. The effect of the complexing action of such a strong inorganic acid can be overcome by increasing the concentration of the fluorinated fl-diketone in the organic solvent. It is preferred that the concentration of the fluorinated fl-diketone in the organic solvent be at least 0.01 M and concentrations of at least 0.03 M are especially preferred. The efliciency of extraction is increased with increasing amount of chelating agent and the efficiency is approximately inversely proportional to the third power of the hydrogen ion concentration.

The ratio of the organic solvent solution to aqueous solution may be varied considerably, but the preferred range of ratio is between 10:1 and 1:10.

Examples of suitable water-soluble salts of tetravalent zirconium that may be used as aqueous solutions heretofore defined are as follows: zirconyl chloride and zirconium nitrate. Of course, when these tetravalent zirconium salts are present in low concentrations, especially in tracer concentrations, such as concentrations of the order of 10- to 10 M, the ionic species of zirconium has been found to be Zr(OH)+ at acidities of about 0.005 N and higher and Zr(OH) or ZrO+ at lower acidities. In aqueous solutions having acid concentrations of less than 0.1 N there is considerable zirconium loss from solutions by hydrolyzing of zirconium; therefore, an acidity of at least 0.1 N is preferred.

The new compounds of zirconium of this invention are compounds of tetravalent zirconium and the fluorinated fi-diketones. They are represented by the following general formulas:

wherein R, R and R represent the'same groups as indicated above for the general formula of the chelating agent. It is seen that there are two possible formulas for the zirconium chelate compounds, since the p-diketone may enolize in either of two ways. In either case, zirconium is bonded to the oxygen atoms by a covalent bond and a coordinate bond and due to resonance the two compounds would be identical. These compounds are solids which have a negligible solubility in water, and which are soluble in benzene, toluene and other organic solvents. The solubility of zirconium chelate compound of 2-thenoyltrifluoroacetone at various temperatures has been studied and the data are presented below in the examples of the process. These chelate compounds are destroyed by aqueous solutions containing agents that form water-soluble complexes with zirconium, e.g., oxalic acid and hydrofluoric acid. These chelate compounds or coordination compounds of tetravalent zirconium and the fluorinated ,B-diketones are colored and those of natural-ocourring or nonradioactive zirconium may be used to form decorative coatings.

In one embodiment of this invention the zirconium chelate compound is prepared by contacting an aqueous solution containing a tetravalent zirconium salt with a fluorinated B-diketone of the type described above or with an organic solvent solution of the fluorinated fi-diketone.

In this embodiment the amount of fluorinated B-diketone used is preferably less than the stoichiometric amount for the formation of the tetravalent zirconium chelate compound so that the latter when formed will not be contaminated with excess fluorinated B-diketone when precipitated from the aqueous solution or when extracted from the aqueous solution where organic solvent is used. The aqueous solution used in this embodiment contains the strong inorganic acid in the concentration described above. Other conditions such as the ratio of organic solvent solution and aqueous solution are those mentioned above. When the fiuorinated fi-diketone is used alone the precipitated chelate compound is separated by settling, centrifugation, filtration or other suitable means. When an organic solvent solution of fluorinated/S-diketone is used the resultant aqueous phase and organic solvent extract phase are separated, e.g., by settling or centrifugation, and the organic solvent extract phase contains a zirconium chelate compound of the fluorinated ,B-diketone.

In the second embodiment of the present invention zirconium is separated from aqueous solution containing the tetravalent zinconium salt by contacting the aqueous solution as described in the first embodiment. The amount of fluorinated fl-diketone is preferably much greater than the stoichiometric amount for the formation of tetravalent zirconium chelate compound. In this embodiment the conditions described above for acidity of the aqueous solution, temperatures, etc. are used.

The zirconium may be separated from the organic solvent solution of zirconium chelate compound by contacting the solution with an aqueous solution containing an agent which converts zirconium of the chelate compound to a water-soluble, organic-insoluble compound and separating the resultant organic solvent phase and aqueous extract phase containing a zirconium compound. The volume ratios of organic solvent solution and aqueous solution and other conditions may be varied as in the case of the first embodiment. Examples ofcomplexing agents suitable for converting zirconium into water-soluble complexes are hydrofluoric acid and oxalic acid. The concentration of complexing agent can be varied widely, e.g., between 1X10" to 1 M, and it varies with the particular agent, the zirconium concentration in the organic solvent solution from which it is to be extracted, and the total amount of free and combined fluorinated p-diketone.

The zirconium may also be separated from the organic solvent solution of tetravalent zirconium chelate compound by diluting the organic solvent solution with an additional quantity of organic solvent to provide a maximum concentration of free and combined fiuorinated fl-diketone of less than 0.01 M and contacting the resultant diluted solution with an aqueous solution containing at least 1 N strong inorganic acid and preferably at least 2 N strong inorganic acid. It is also preferred that this aqueous solution contain a complexing agent of the type described above to enhance the extraction of zirconium into the aqueous solution. The aqueous extract phase and organic solvent phase are separated by settling or centrifugation.

In a third embodiment of this invention zirconium is separated from its aqueous solution by contacting the aqueous solution of the type described above with a chelating agent of this invention in the absence of an organic solvent and at a temperature above the melting point of the B-diketone. The amount of the fluorinated fl-diketone chosen is a considerable excess so that excess fl-diketone acts as a solvent for the zirconium chelate compound.

In a fourth embodiment of this invention zirconium is separated from an aqueous solution containing salts of tetravalent zirconium and another metal, such as pentavalent columbium, yttrium, rare earths in the trivalent state, alkaline earths, or mixtures thereof. The aqueous solution, of course, contains the strong inorganic acid in the concentration described above and preferably 0.1 to 2 N. Other conditions are those of the second embodiment.

Another embodiment comprises separating zirconium from an organic solvent solution of a zirconium chelate compound of a fluorinated S-diketone of the formula presented above. The process of this embodiment is described in the second embodiment in conjunction therewith as a complete extraction and re-extraction process.

The following examples taken alone and in combination illustrate the embodiments of this invention.

EXAMPLE 1 Table I Element: Distribution of coeflicient 1 Zirconium Plutonium 26 Columbium 0.054 Strontium 0.0077 Yttrium 0.007 1 Cerium (trivalent) 0.0006

1 Distribution coefiicient is the ratio of concentration of the metal value in organic solvent and aqueous phases.

EXAMPLE II A solution of 1 M Z-thenoyltrifluoroacetone in anhydrous benzene was allowed to evaporate in contact with a quantity of a 0.1 M zirconyl chloride in 5 N perchloric acid to provide the stoichiometric amount of zirconium assuming the chelate compound formed contained four B-diketone groups united with one atom of zirconium. The product obtained was filtered and washed with water to remove excess salt and acid. The product was then washed with benzene to remove any excess Z-thenoyltrifluoroacetone and air was drawn through the filter to evaporate the residual benzene. The product was dried at room temperature over a desiccant. A 0.2097-g. sample of the product was analyzed by moistening with concentrated sulfuric acid followed by ignition to zirconium dioxide. Zr found was 0.0262 g., which is in agreement with the calculated weight for ZrO of 0.0265 g., assuming the chelate compound or complex produced was obtained by the substitution of one hydrogen atom in each of 4 molecules of 2-thenoyltrifluoroacetone with one atom of zirconium, i.e., assuming the compound was zirconium tetrakis(2-thenoyltrifluoroacetonate).

The solubility of this zirconium chelate compound in benzene at various temperatures was determined by rotating a quantity of the chelate compound at each temperature with about 7 ml. of the solvent in a constant temperature bath for five to twenty hours and then removing a -ml. sample through a cotton filter for analysis. More solvent was then added to the remaining portion of the tetravalent zirconium chelate compound of 2-thenoyltrifiuoroacetone and the process was repeated until consistent values were obtained as shown by the analyses. The analyses of zirconium chelate compound dissolved in the benzene were made by evaporating the 5-ml. samples in vacuo, weighing to obtain total solute, moistening it with sulfuric acid, igniting, and weighing the 210 obtained. The results are presented below in These data calculated concentrations for the chelate compound in benzene of 0.018, 0.026, and 0.038 M for 20, 30, and 40 C. respectively.

The foregoing description and data illustrate one method of preparing the tetravalent zirconium chelate compounds of the present invention and illustrate the solubility of this type of compound in an organic solvent.

A similar study of the solubility of the chelate compound in anhydrous benzene containing various concentrations of Z-thenoyltrifluoroacetone at 20 C. and in water-saturated benzene at 20 C. was carried out. The solubility data were substantially the same as the value of 10.7 mg. calculated as ZrO /5 ml. presented above, for example, the solubility in 0.08 M 2-thenoyltrifluoroacetone solution in anhydrous benzene was 10.9 mg. calculated as ZrO /5 ml.

EXAMPLE III A 0.086 M zirconyl chloride solution in 5 N perchloric acid was treated with various benzene solutions of 2-thenoyltrifluoroacetone. Distribution coefiicients for zirconium between organic and aqueous phases as high as 161 were obtained.

EXAMPLE IV In some of the following experiments tracer concentrations of radioactive zirconium were used. In other experiments macroconcentrations of nonradioactive zirconium were used. The inactive zirconium used was ZrOCl .6H O which was recrystallized several times from concentrated hydrochloric acid to give relatively large needles of pure white ZrOC] .8I-l O. This salt was used to prepare an aqueous solution containing 0.1 M Zr(IV) in l N perchloric acid, thus making the solution 0.2 M in chloride ion. The solution was clear, giving only a slight Tyndall beam, and remained so over a period of several months. The radioactive zirconium used was quite pure, except for columbium produced by zirconium disintegration. The zirconium was further separated from the colmnbiurn by providing a 1 N nitric acid solution containing the radioactive zirconium, extracting the zirconium into a benzene solution of 2-thenoyltrifluoro acetone and washing the benzene phase with 2 N perchloric acid. The benzene solution was diluted tenfold with benzene and the zirconium was re-extracted'by a small volume of 2 N perchloric acid.

The following experiments were carried out by mixing 25 ml. each of an aqueous solution and a benzene solution of 2-thenoyltrifluoroacetone in a -ml. flask using vigorous shaking while in a 25 C. constant temperature bath.

In the experiments using macroconcentrations of zirconium a colorimetric method of zirconium analysis of aqueous phase using alizarin for determining zirconium was used. The reproducibility of the alizarin method of analysis was of the order of 3%. In the experiments using tracer concentrations of zirconium the analyses for zirconium were carried out using usual radioactive counting methods. Aliquots from both aqueous and solvent phases, usually 0.1 ml., were counted on glass cover slides using a Geiger counter or a vibrating reed electrometer equipped with a recording potentiometer.

Table III presented below shows the effect of increased Z-thenoyltrifiuoroacetone concentration in the benzene upon the increase of the zirconium distribution coefficient. The aqueous solution used contained 2 N perchloric acid and a tracer concentration of Zr(IV) salt.

Table III Zr Distribution Ooefiicient l H thnooco s w-canoe wmuswcrenmm 1 See footnote to Table I for definition.

Table IV below presents the data on the study of the effect of varying the Zr(IV) concentration on the extraction coefficient using 2 N perchloric acid and using 0.01 M 2-thenoyltrifluoroacetone solution in benzene. The coeflicients are corrected in the third column to the values that would be obtained if the free p-diketone concentration were the same in the other experiments as in the tracer experiment.

These data show that the extraction is substantially unefiected by a variation in the zirconium concentration in the aqueous solution from which it is chelated-extracted. Of course, the distribution coefiicient can be increased by increasing the concentration of iluorinated fl-diketone in the organic solvent; for example, using a benzene so1ution containing 0.04 M Z-thenoyltrifluoroacetone and 2 N perchloric acid containing about 0.003 M Zr(IV) a zirconium distribution coeflicient (organic solvent/aqueous) of about were obtained.

Table V presents data from the experiments studying. the dependence of zirconium extraction or distribution on the hydrogen ion concentration. The data were obtained using aqueous solutions containing tracer concentrations of Zr(IV) at 25 C. V V

9 Table V Zr Distribution Coefliclent 1 1 See footnote of Table I for definition.

The gamma counts per minute in the aliquot of the benzene phase for the experiments using an aqueous solution containing 0.012 perchloric acid and 0.0012 M 2- thenoyltrifluoroacetone in benzene were 2,950 as compared with 70 beta counts per minute in the aliquot of the aqueous phase. Using these analyses the zirconium distribution coeflicient was determined to be 42.5. These data also illustrate the concentration of the tracer solution used. V

Thezirconium distribution coefiicient between organic and aqueous phase using a tracer solution of Zr(IV) containing 0.27 M sulfuric acid and perchloric acid to provide a 2 M total acidity at 25 C. and using a benzene solution containing 0.05 M 2-thenoyltrifluoroacetone was 0.69. Other data show that the complexing effect of sul-. fate anion, which reduces the distribution coeificient, can be overcome by providing a sutficiently high concentration of fluorinated fi-diketone, such as Z-thenoyltrifluoroacetone. I

In Table VI below the zirconium distribution coeflicients are presented to show the very marked effect of hydrofluoric acid upon the zirconium distribution coefiicient. These data were obtained using 'a tracer solution of Zr(IV) containing 2 N perchloric acidiat 25 C. and benzene solutions of Z-thenoyltrifluoroacetone.

. See footnoteoi Table I for definition.

' The foregoing data show zirconium can be extracted by contacting the organic solvent'solutio'n of the tetravalent zirconium chelate compound of fluorinated fi-diketone with an aqeuous solution containing hydrofluoric acid. The degree of extraction is dependent upon the HF concentration and dependent upon the total concentration of free and combined fluorinated fi-diketone in the organic solvent.

EXAMPLE V A uranium slug from a neutronic reactor was dissolved in nitric acid to provide a solution containing 2.3 M uranyl nitrate and 0.33 N nitric acid. The solution contained a small amount of plutonium and about 0.1 curie of beta and gamma radiation per ml. The solution was stored for 100 days from the time that the slug was removed from the neutronic reactor. The distribution of beta activity was calculated to be approximately as follows: 26% Ce, 26% Sr, 23% Y, 12% Zr, 3.5%

Ru, 3.2% Cb, as counted through 11 mg./cm. total absorber. One ml. of this solution was mixed with 1 5 ,B-diketone under these radiation conditions.

of 0.5 M Z-thenoyltrifluoroacetone in benzene. Aliquots of the benzene layer were removed at various time intervals and 2-thenoyltrifluoroacetone analyses were carried out to determine the stability of the fluorinated The mixing time was a total of 45 hours. The Z-thenoyltrifluoroacetone analyses indicated that the compound was stable under these radiation conditions.

EXAMPLE VI A series of experiments was carried out in which benzene and hexone solutions of 2-thenoylt1ifluoroacetone were agitated with aqueous solutions having the nitric acid concentrations indicated in Table VII presented below. In some of these experiments zirconium tracer was initially present as chelate compound in organic solvent and in other experiments it was initially present in the aqueous solution. The initial aqueous solution in the first and second experiments also contained 2.3 M uranyl nitrate. The initial aqueous solution in the third and fourth experiments contained 3'N sulfuric acid. In the fifth experiment the aqueous solution contained 0.09 M oxalic acid. In the last three experiments the aqueous solutions contained aluminum nitrate in a concentration of 0.75, 0.7; and 0.7 M respectively.

In the first experiment in Table VII the equilibrium was reached in twominutes. In the second experiment only of equilibrium was reached in six minutes, but before fourteen minutes complete equilibrium was attained. The data of the table show the extraction and re-extraction of process of the present invention using benzene and hexone. It was found rfrom these and other experiments that the concentration of 2-thenoyltrifluoroacetone in hexone required to attain the same level of extraction of Zr(IV) was three to four times as high as the concentration in benzene. I

EXAMPLE VII A series of extraction experiments of zirconium from benzene solution of the tetravalent zirconium chelate compound of 2-thenoyltrifluoroacetone and containing 0.1 M Z-thenoyltriflnoroacetone using various aqueous media was carried out. Equal volumes and a mixing for twenty minutes were used in each case. The data are presented in Table VIII.

Table VIII Diketone Cohen, Zr Distri- M v Aqueous Solution bution Coefficient 1 0. H2O 81 0. 1 N H 0. 04 0. 2 N H 0. 03 0. 9.6 N HNOa 0.006 0. 0.1 M H2020; and 2 N H0103... 0. U1 0. H1O. 249 0. l M H0 107 0. 0.1 M H2020 I. I 0. 0.5 N HF 0. 09 1 H1O 1---. 0.5 N HNOs--- 182 1 1 N HNO; 60

l See footnote of Table I for definition.

- These data show that the chelate compound of this invention can be extracted by diluting the organic solvent solution to provide a total chelate agent concentration of 0.01 M or less and/or by using complexing agents, such as oxalic acid and hydrofluoric acid.

EXAMPLE VIII Aqueous solutions containing 0.5 N nitric acid and individual tracer concentration of radioactive metal salts were mixed in each case with an equal volume of 0.03 M 2-thenoyltrifluoroacetone solution in benzene for fifteen minutes. The extraction data are presented in Table Tab'le IX Distribution Tracer Element Coetl-lcient 1 Ch a. 4 X Zr 1.3 1 X 10% C III ca. R?l ca. 1 X 10 1 See footnote of Table I for definition.

The data were based upon the determination of the beta activity of these tracer elements in the organic and aqueous phases at equilibrium.

EXAMPLE IX In a study of the chelation-extraction of tracer zirconium from 2 N nitric acid by agitation for ten minutes by an equal volume of xylene containing various concentrations of Z-thenoyltrifluoroacetone the percent zirconium extracted was determined. The data are presented below in Table X.

It was found that the extraction of tracer zirconium from 0.5 to 8 N nitric acid and from 1 to 12 N hydrochloric acid was between 98 and 100%. There was no extraction of tracer zirconium from an aqueous solution containing 1% oxalic acid, but when the solution also contained 10 N hydrochloric acid or 13 N nitric acid the zirconium extraction was 50 and 87% respectively.

The process of the present invention may be carried out using batch or continuous conditions with equipment commonly used for cocurrent or countercurrent operation in the continuous process.

The foregoing illustrations and embodiments of this invention are not intended to limit its scope, which is to be limited entirely by the appended claims.

What is claimedis:

l. A process for the separation of zirconium from a mixture containing zirconium, columbium, a rare earth, and an alkaline earth, which comprises contacting an aqueous solution containing salts of tetravalent zirconium, pentavalent columbium, a rare earth in the trivalent state, and an alkaline earth and containing at least 0.001 N of a strong inorganic acid with a solution in a substantially water-immiscible organic solvent of a fluorinated diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine, and separating the resultant aqueous phase containing said salts of columbium, rare earth, and alkaline earth and organic solvent extract phase containing a zirconium chelate compound of the fluorinated fi-diketone.

2. The process of claim 1 in which the fluorinated fi-diketone is trifluoroacetylacetone.

3. 'I'he process of claim 2 in which the organic solvent is benzene.

4. The process of claim 1 in which the fluorinated S-diketone is benzoyltrifiuoroacetone.

5. The process of claim 1 in which the fluorinated fi-diketone is 2-thenoyltrifiuoroacetone.

6. The process of claim 5 in which the organic solvent is benzene.

7. The process of claim 1 in which the fluorinated fi-diketone is Z-thenoyltrifiuoroacetone and in which the organic solvent is xylene.

8. The process of claim 1 in which the fluorinated ,B-diketone is 2-thenoyltrifluoroacetone and in which the organic solvent is hexone.

9. The process of claim 1 in which the inorganic acid is nitric acid and the concentration is between 0.1 and 2 N.

10. The process of claim 1 in which the inorganic acid is hydrochloric acid and the concentration is between 0.1 and 2 N.

11. A process for the separation of zirconium from a mixture containing zirconium, columbium, a rare earth, and an alkaline earth, which comprises contacting an aqueous solution containing salts of tetravalent zirconium, pentavalent columbium, a rare earth in the trivalent state, and an alkaline earth and containing at least 0.001 N of a strong inorganic acid with a solution in a substantially water-immiscible organic solvent of a fluorinated fi-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine, separating the resultant aqueous phase containing said salts of columbium, rare earth, and alkaline earth and organic solvent extract phase containing a zirconium chelate compound of the fluorinated p-diketone, contacting said extract phase with an aqueous solution containing oxalic acid which converts zirconium of said chelate compound to a water-soluble, organic solvent-insoluble compound, and separating the resultant organic solvent phase and aqueous extract phase containing a zirconium compound.

12. A process for the separation of zirconium from a mixture containing zirconium and columbium, which comprises dissolving said mixture in an aqueous solution of a strong inorganic acid to provide a solution having at least 0.001 N acid concentration and salts of tetravalent zirconium and pentavalent columbium, contacting said solution with a substantially water-immiscible organic solvent solution of a fluorinated fl-diketone wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydro gen and fluorine, and separating the resultant aqueous phase and organic solvent extract phase containing a 13 zirconium chelate compound of the fluorinated fi-diketone.

13. The process of claim 12 in which the inorganic acid is nitric acid in a concentration of 0.1 to 2 N, in which the fluorinated ,B-diketone is trifluoroacetylacetone, and in which the organic solvent is benzene.

14. The process of claim 12 in which the inorganic acid is nitric acid in a concentration of 0.1 to 2 N, in which the fluorinated ,B-diketone is 2-thenoyltrifluoroacetone, and in which the organic solvent is benzene.

15. A process for the separation of Zirconium from a mixture containing zirconium and a rare earth, which comprises dissolving said mixture in an aqueous solution of a strong inorganic acid to provide a solution having at least 0.001 N acid concentration and salts of tetravalent zirconium and rare earth maintained in the trivalent state, contacting said solution with a substantially water-immiscible organic solvent solution of a fluorinated p-diketone having the general formula:

RCf-OH2C(JZR wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine, and separating the resultant aqueous phase and organic solvent extract phase containing a zirconium chelate compound of the fluorinated fi-diketone.

16.' A process for the separation of zirconium from a mixture containing zirconium and alkaline earth, which comprises dissolving said mixture in an aqueous solution of a strong inorganic acid to provide a solution having at least 0.001 N acid concentration and salts of alkaline earth and tetravalent zirconium, contacting said solution with a substantially water-immiscible organic solvent solution of a fluorinated fl-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine, and separating the resultant aqueous phase and organic solvent extract phase containing a zirconium chelate compound of the fluorinated B-diketone.

17. A process for the separation of zirconium from an organic solvent solution of a tetravalent zirconium chelate compound of a fluorinated B-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicmls and R and R are members of the group consisting of hydrogen and fluorine, which comprises contacting said solution with an aqueous solution containing oxalic acid which converts zirconium of said chelate compound to a water-soluble, organic solvent-insoluble compound, and separating the resultant organic solvent phase and aqueous phase containing a zirconium compound.

18. The process of claim 17 in which the chelate compound is a compound of zirconium and Z-thenoyltrifluoroacetone and in which the organic solvent is benzene.

19. The process of claim 17 in which the chelate compound is a compound of zirconium and trifluoroacetylacetone and in which the organic solvent is benzene.

20. A process for the separation of zirconium from an organic solvent solution of a tetravalent zirconium chelate compound of a fluorinated 8-diketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine, which comprises contacting said solution with an aqueous solution containing hydrofluoric acid which converts zirconium of said chelate compound to a water-soluble, organic solvent-insoluble compound, and separating the resultant organic solvent phase and aqueous phase containing a zirconium compound.

21. A process for the separation of zirconium from an organic solvent solution of a tetravalent zirconium chelate compound of a fluorinated fl-d-iketone having the general formula:

wherein R is a member of the group consisting of alkyl, aryl, aralkyl, alkaryl and heterocyclic radicals and R and R are members of the group consisting of hydrogen and fluorine, which comprises diluting said solution with solvent to provide a final total free and combined concentration of fluorinated ,B-diketone of less than 0.01 M, contacting the diluted solution with an aqueous solu tion containing at least 1 N strong inorganic acid, and separating the resultant organic solvent phase and aqueous phase containing a zirconium compound.

22. The process of claim 21 in which the strong inorganic acid is nitric acid and the acid concentration is at least 2 N.

References Cited in the file of this patent UNITED STATES PATENTS 2,161,184 McKone et al. June 6, 1939 2,227,833 Hixson et al. Ian. 7, 1941 FOREIGN PATENTS 289,493 Great Britain Apr. 30, 1928 OTHER REFERENCES Huffman et al.: The Separation of Zirconium and Hafnium by Extraction With Thenoyltrifluoroacetone, AECD-2387, October 7, 1948, 5 pages. Technical Information Branch, Oak Ridge, Tenn.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2 892 68l June 30, 1959 Howard W. Crandall et alo It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7 Table II second column, line 1 thereof for "8206" read 86,2 column 12 lines 65 to 70 the formula should appear as shown below insiaead of as in the patent:

Signed and sealed this 8th day of October 1963,

(SEAL) Attesti EDWIN Lo REYNOLDS ERNEST W. SWIDER Attesting Officer AC ting Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE, OF CORRECTION Patent N0o 2 892 68l June 30 1959 Howard W, Crandall et al,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, Table Il second column,line l thereof for "82.6" read 86,2 column 12 lines 65 to 70 the formula should appear as shown below inst zead of as in the patent:

Signed and sealed this 8th day of October 1963.,

(SEAL) Attest:

EDWIN Lo REYNOLDS ERNEST W. SWIDER fiesting Officer AC t i n q CommissionQr Patents