DE1803344C - Process for the production of ammonium uranium (IV) pentafluoride - Google Patents

Description

The invention relates to a method for production by AmmoniiinuiranOVl-penlullt'orid.

Aminoniumuran (IV) -pentafluorid, NLL ₁ I) I ¹¹ S, which is sometimes referred to as NIl ₄ I- '· Ul ·'. Specified, is, rope known for many years and is as an intermediate / for successive production of Urantetralluorid (UF ₄ ), Uranium hexalluoride (UF ,,) and uranium metal. These products are suitable for the production of fissile uranium metal as well as for the production of nuclear fuels (e.g. UC) to generate electricity. This compound is a green crystalline solid, which is known to occur in two different crystal forms, which are referred to as <i or // forms and are characterized by their X-ray diffraction imisters (cf. Inorganic Chemistry 2, p. 7 ¹ W to 893 [ 1963]) differ.

Up to now, ammonium uranium (IV) pentafluoride was produced by reacting ammonium luoride with uranium tetrafluoride produced under anhydrous conditions. This procedure is technically uninteresting, as it requires the use of pure reagents, in addition to making the finished anhydrous Product essentially requires the exclusion of water.

In the conversion of ammonium uranium (V) pentafhoride to uranium hexalluoride by known methods, the NH ₄ UF _{5 is} first heated to its decomposition temperature, whereby uranium tetratluoride and ammonium fluoride are produced. Practically all impurities in the NH ₄ UF _{5 are introduced} into the UF ₄ . The solid uranium tetrafluoride is then obtained and, for example, fluorinated in a fluidized bed to obtain gaseous uranium hexalluoride. The uranium tetrafluoride must be relatively free of impurities, especially sodium and / or potassium compounds, since these impurities are fluorinated to solid sodium and potassium luoride, these salts remaining in the fluidized bed and accumulating there, possibly melting and consequently inactivation cause of the fluidized bed. Therefore, the UF _{4 should} preferably contain no more than about 0.25% (250 ppm) total sodium and potassium impurities (parts and percentages are based on weight). This criterion requires corresponding purity requirements for the ammonium uranium (IV) pentafluoride, from which UF _{4 is obtained} for the fluidized fluorination. Such NH ₄ UF ₅ products should similarly no more than about 25 (H) ppm (0.25%), and preferably less than about 2000 ppm (0.20%) of sodium and potassium (combined) based on the Uranium as a metal.

In order to obtain UF ₄ products with correspondingly low sodium and potassium contents for fluidized bed purposes, it has hitherto been necessary to process ore concentrates with relatively low sodium and potassium contents in order to achieve the required low sodium and potassium values in the UF ₄ obtained. For example, it has been necessary to start with ore concentrates containing no more than about 3 (HX) ppm (0.30%) sodium and potassium (combined) based on the uranium in the ore.

Other metallic impurities are also in UF, UF and _h, which are used for various purposes, undesirably, so that the I lerslollcr limits have been set for a number of impurities in addition to sodium and potassium. Vanadium and molybdenum should be mentioned of these impurities, these lilemems being harmful in that they _{are converted into their volatile fluorides during the fluorination of LJF 4} to IM · ',, which tend to settle on the system during the distillation of the LJF ,, knock down.

Aiumoniunuirand V) pentalluoride produced in the crystalline form has been found to consistently contain lower levels of impurities than the crystalline / (- material produced from the same uranium ore In particular, it has been found that the pollution from sodium and potassium is low. The reason for this phenomenon is not fully understood, but it is believed that the crystalline lattice accepts fewer heteroatoms than does the // lattice is. Ls, therefore, is desirable in the \ Ierstcllung of ammonium uranium (l V) -pentafluorid used for the recovery of UF _4, which is optionally used in Uranhexalluorid by a Fließbettlluoricrung, a Ammoniumuraii (IV) -pentalUiorid in the crystalline. «-Form

The invention relates to a process for the production of crystalline ammonium uranium (IV) penlafluoride, which is predominantly in the crystalline form and less than about 2500 parts Contains sodium and / or potassium per 1 million parts of uranium, the process also being based on uranyl salt Solutions derived from ore concentrates containing more than 0.3% and even up to Contains 3% sodium and potassium (taken together). The process according to the event exists therein, at a temperature of at least 85 C, hydrogen fluoride, hydroxylamine or a hydroxylamine supplying compound and an aqueous solution of a uranyl salt, the chloride, copper (II) - and It contains ammonium ions to decompose, with the concentration of hydroxylamine acting as such or in the form of a hydroxylamine-donating compound is present in the solution to at least 0.07 moles per liter of the solution is kept with at least 75% of the uranium in crystalline ammoniumimuran (IV) pentalluoride being transformed.

Preferably, the hydroxylamine or the hydroxylamine-providing compound is added in portions during the course of the reaction in a total amount of 1.0 to 1.5 moles per mole of uranium and at such a rate that the concentration of hydroxylamine, either as such or in the form of a Hydroxylamine-providing compound is maintained between 0.07 and 0.50 moles per liter of solution until at least 75% of the uranium has been converted to crystalline ammonium uranium (IV) pentalluoride. Furthermore, the molar ratio of chloride ions to copper (M) ions is preferably used at least; 4: 1 and the amount of hydrogen fluoride used is at least so large that all the uranium present is converted into ammonium uranium (IV) pentalluoride, choosing at least 0.01 mol Cu ^{1 f} ions per Liier solution and at least 1 mol grazing and preferably I to I ₁ S Ammouiumionen moles per mole of uranium eingesel / t. _{UO 2} F ₂ is preferably used as the aryl salt, and the hydroxylamine is

e als (him oiler nls llydroxykmimsnlz / u-

is

The uranyl salt soluble in the successful process can be obtained from uranium ore concentrates by adding an acid, for example hydrofluoric acid, hydrochloric acid or sulfuric acid, to obtain the corresponding uranyl luoride, chloride or uranyl chloride. Preferably the fluoride (UO ₂ Is) is used because this compound is more economical in terms of total acid consumption and provides two of the five fluoialoins required in the ammonium uranium (IV) pentalluoride end product. The following explanations therefore relate to the use of Ufauyllliiorid as an example for Uianylsalzc. Instead of UO ₂ F ', however, the sulfate (UO ₁ SOj) or the chloride (UO ₂ Cl ₂ ) can also be used, the amount of HF used being increased in a corresponding manner by the five fluorine atoms required for the NII ₄ UF ₅ final product to be delivered

These ore concentrates, which for example consist mainly of uranium oxides and / or their hydrates and preferably mainly contain UO, or its hydrates, some U ₁ O ₈ or LJO, being present and the concentration of these compounds usually between about 70 and i) 5 ( Weight percent or more will almost always contain small to appreciable amounts of impurities which may vary depending on the source and method of concentrating the ore. Commonly present impurities are sodium and / or potassium (in amounts of approximately 0.2 Percent by weight, if special VVi.ubeitimgsstufen are carried out, and up to 3 percent by weight or even more), these impurities are often associated with other impurities, such as vanadium, molybdenum, iron or copper compounds Ore concentrate slurried with water, the water being an acid , preferably hydrofluoric acid, either as gaseous hydrogen fluoride or in the form of an aqueous hydrofluoric acid solution has been added to provide at least about 2 moles of HF per mole of uranium in the ore. An excess of HF can optionally be added. The mixture obtained is stirred until the ore concentrate appears to be essentially completely dissolved, so that in this way a uranyl salt solution is formed which mainly contains UO ₂ F, together with practically all of the impurities that were originally contained in the ore concentrate, the remainder being made up of excess HF, if HF is still present. The hydrogen fluoride is also dissolved in the solution.

By uranyl luoride solution or another uranyl salt solution, which has been prepared in this way, hydrogen fluoride is added, and preferably in an amount that is at least sufficient to include the 5 moles of fluorine per mole of uranium which Im the end product are required to make available / u. It also becomes a catalytic amount of a soluble one Copper salt, for example copper sulphate or chloride, preferably in an amount of at least Approximately O ΙΠ moles of copper (II) ions per liter of solution.

30th

35

40

45 and a chlorine ion (Cl) ion is added as a stabilizer for the copper ions, the chloride ions preferably being added in an amount sufficient to set a Cl: Cu '' mismatch of at least approximately 4. A soluble ammonium salt, for example ammonium sulfate, is added to provide ammonium ions, preferably in amounts of about 1 mole of NII ₄ per mole of uranium in the solution. The ammonium ion level is not unduly critical. Usually the ammonium ions should be added in amounts between about 1 mole and about 1.5 moles per mole of uranium.

The ammonium salt can be added fresh or in the form of a recyclable liquid which is obtained after the ammonium uranium (IV) pentalluoride has been separated off. As the ammonium salt. the ammonium fluoride, which is obtained in the subsequent pyrolysis of NH ₄ UF ₅ into UF ₄ and NH ₄ F, can also be added.

Suitable ammonium salts are ammonium sulfate, chloride and bisulfal. Mixtures of ammonium salts can also be used. However, it is preferable to refrain from using ammonium nitrate (NH ₄ (NO ₁ )) unless this compound is added in small amounts, as this salt tends to consume hydroxylamine due to its oxidizing properties.

The dissolved ore solution, which contains UO ₂ F ₂ along with copper, chloride and ammonium ions, is heated to at least about 85 ° C., and preferably to a temperature between about 95 and about 105 "C. During the addition of hydroxylamine or a hydroxylamine The hydroxylamine or hydroxylamine-donating compound can be added in a single batch or in portions in such an amount that the hydroxylamine concentration is maintained at a value not appreciably lower than about 0.07 mole Hydroxylamine per liter of solution during the main course of the reaction, that is, until at least about 75% of the uranium in the solution has been converted to ammonium uranium (IV) pentafluoride.

The method according to the invention can be represented in summary form by the following equation :

- Cu ^{+ +}

UO ₂ F, t- 2HF l • NH ₄ F l • NH ₁ OH ⁺ >

he

NH ₄ UF ₅ + 1 / 2N ₂ O t- 2- 1 / 2H ₂ O 4- H ⁺

The reaction is rapid within ites preferred temperature range. Substantially complete precipitation of the NH ₁ UF ₅ is generally accomplished in no more than about 30 minutes, this period of time often being between about 5 and 25 minutes and often times of as little as about 5 to 10 minutes being required.

The hydroxylamine can, as such or in the form of a convenient manner, provide hydroxylamine Connection. Instead of hydroxylamine itself, one or more can be used Hydroxylamine salts, for example Hydroxylaininsul-

i 803 344

fal, (NHjOII) ₂ SU ₁ ,, hydroxylumin ^{bisulful, 1} NH ₃ OH ■ HSO ,,, or hydroxylamine hydrochloride, NH ₃ C) IICI, use. Also suitable as hydroxylamine-yielding compounds are the oximines, ie compounds of the formula

• \

= NOH

wherein R ₁ and R ₂ ft ^{| rc 'nc} Alkylgiuppe having 1 to 6 carbon atoms, or R, and R ₂ together form a cyclohexyl group. For example, it can be acetoxime, (CHj) ₂ C =NOII, cyclohexanone oxime or methyl isobutyloxime, hydrolysis in aqueous acidic solution yielding hydroxylamine and the corresponding ketone.

To ensure complete conversion of the uranium into ammonium uranium (IV) pentafluoride is the total amount of hydroxylamine used, either as such or in the form a hydroxylamine-donating compound, generally at least 1 mole per mole of uranium.

The hydroxylamine acts as a reducing agent to convert Cu ⁺⁺ into Cu ⁺ , which then acts to reduce the hexavalent uranium to the tetravalent state, again Cu ^{+ H} according to the equation

2Cu ^{+ +} + NH ₃ OH '

--- »2Cu ⁺ + 1 / 2N ₂ O + 1 / 2H ₂ O + 3H ⁺

is produced.

It has also been found, surprisingly, that the relative concentration of hydroxylamine in the reaction medium critically determines the crystal structure of the precipitated crystalline NH ₄ UF ₅ . If the concentration of the hydroxylamine is above approximately 0.07 mol per liter of solution, then ammonium uranium (IV) pentafluoride is formed. If the concentration of hydroxylamine falls below approximately 0.07 mol per liter of solution, then / (- ammonium uranium (IV) pentafluoride precipitates kept in the reaction mixture above the critical limit when the majority of the uranium in the uranyl salt has been converted into NH ₄ UF _5. This can optionally be achieved by adding a large excess of hydroxylamine to the reaction mass at the beginning of the reaction, with a such an excess is sufficient to maintain the required concentration of hydroxylamine during the reaction period, even after some of the hydroxylamine has decomposed, which may occur in the reaction medium To provide hydroxylamine per mole of uranium available in order to provide the one mole that is necessary for e a complete response is required. after the hydroxylamine lost through decomposition has been compensated. However, such a procedure has the disadvantage that it is costly in terms of hydroxylamine, and there is also a tendency that considerable amounts of NH ₃ OHUF ₅ are formed as a by-product in the precipitate.

It has been found, however, that the required concentration of hydroxylamine can be maintained can, taking significant amounts of hydroxylamine

ίο can be saved and an essentially complete suppression of the formation of / (- NH ₄ UF ₅ and NH ₃ OHUFj is possible by adding a smaller initial charge of hydroxylamine, which is then added in portions

of the hydroxylamine connects. The initial / .ugabe as well as the subsequent additions are like this adjusted to have a hydroxylamine concentration between about 0.07 moles and about 0.50 moles per liter of solution during the predominant

NH ₄ UF ₅ precipitation period is maintained, preferably until at least about 75% of the uranium in solution has been precipitated _{as NH 4} UF _5. Hydroxylamine concentrations below about 0.08 mol per liter result in the formation of / (- crystals. Concentrations above about 0.50 mol per liter produce NH ₃ OHUF ₅ as an impurity. This latter compound, although obviously due to the Quality of the UF ₄ pyrolysis product has no adverse effect, undesirable because it provides water during pyrolysis, which converts part of the uranium into UO ₂ , which consumes 6 fluorine atoms per molecule of UO ₂ during fluorination and therefore excessive fluorine consumption during the subsequent process For example, it has been found that these concentrations can be achieved by adding a total of about 1 mol up to about 1.10 mol of hydroxylamine per mole of uranium in the solution, added in 4 to 6 separate, approximately equal aliquots during a reaction time for a batch process of 15 to 20 minutes or a single aliquot of vo n approximately 0.20 moles of hydroxylamine per mole of uranium in the feed and by subsequent continuous or intermittent addition of hydroxylamine in an amount approximately equal to the amount of hydroxylamine consumed can be maintained.
In order to achieve maximum purity of the product, the hydroxylamine concentration should be kept above the critical 0.07 mol concentration during the entire reaction period. However, such a procedure is costly not only for the hydroxylamine but also for the uranium, since it requires the reaction to be interrupted before the hydroxylamine is consumed and before the uranium reaction is complete before the end of the grooving period. It was found that crystalline ammonium uranium U V) -

fio penlafiuond mil correspondingly high purities (for example 99% and above) for use in the production of UF ₄ according to the fluidized bed process can be produced if the critical concentration of hydroxylamine is maintained for so long

(> 5 will be until at least about 75% of the total Precipitation have occurred. The time span outside the specified limits can not only include the end line span of the reactions during which the

Final amounts of NH ₃ OH ⁺ react, but also the instantaneous drop in concentration below the critical value during the earlier reaction periods, which period of time obviously has little or no adverse effect unless extended excessively.

The process according to the invention can be carried out batchwise or continuously. In either method, some or all of the filtrate obtained after separation of the NH ₄ UF ₅ can be recycled so that the copper and chlorine initially added are not lost and the loss of uranium is also reduced will. Such recycling can be continued until dangerous impurities have accumulated, at which point the entire filtrate can be discarded or parts of the filtrate can be branched off and discarded in an expedient manner.

The ammonium uranium (IV) pentafluoride product is a green crystalline salt which X-ray diffraction analysis indicates that it is predominantly in the crystalline α-form. This is shown by strong diffraction peaks at the d values of 8.4, 3.49, 3.03 and 2.13A, which are characteristic of the U-NH ₄ UF ₅ (cf. Inorganic Chemistry, 2, p. 799 to 803 [1963] p. 802). The NH ₄ UF ₅ salt obtained usually shows only very weak diffraction peaks, the complete absence of such peaks at the (/ values of 6.97, 4.01, 3.48, 3.24 and 2.02 Å being characteristic for the / (- NH ₄ UF _5. The ammonium imine (IV) pentafluoride is also free from contamination by NH ₃ OHUF ₅ , provided that excess hydroxylamine, as explained above, is avoided. This results from the complete absence of X-ray diffraction packs in ( / Values of 7.68, 3.19, 2.42, 2.22, 2.11, 2.07 and 2.00 Å _{, which are characteristic of NH 3 OHUF 5.} The totality of the invention is NH ₄ UF ₅ extremely high. It is usually about 99.5% or more as determined by spatiotemporal analysis, and there are very low levels of harmful impurities, particularly sodium and potassium.

The following examples illustrate the invention. The details relate, unless otherwise indicated on the weight.

example 1

H) Og of an ore concentrate consisting essentially of uranium oxides, mainly UO ₃ , together with small amounts of impurities such as 3000 parts of Na, 200 parts of K, 40 parts of V and 300 parts of Mo per million parts of uranium, and 78.5 % U (equivalent to 78.5 g or 0.33 mol of uranium as metal) are slurried with 250 ml of water in a corrosion-resistant (graphite-impregnated) vessel. To this slurry are added 60 ml (67 g) of an aqueous 48% strength hydrofluoric acid, corresponding to 4.9 moles of HF per mole of uranium in the ore, with stirring. Stirring is continued for approximately 10 minutes until the ore concentrate is essentially completely dissolved. In this way a uranyl salt solution is formed which contains mainly UO ₂ F ₂ , with excess dissolved HF being present along with the impurities noted above.

To the solution described above, 4 g of CuSO ^. 5H ₂ O and then 5 ml of 37% HCl are added, producing a solution containing approximately 3 g of Cu per liter, the HCl / Cu molar ratio being approximately 4. Then 12 g of ammonium fluoride, corresponding to approximately 1 mole of NH ₄ F per mole of uranium, are added to the solution.

The mixture produced in this way is then ^{heated to 100 °} C., whereupon a total of 225 ml (corresponds to 270 g) of an aqueous solution of hydroxylamine sulfate, ammonium sulfate and ammonium bisulfate, which consists of approximately 7 percent by weight of hydroxylamine sulfal (NH ₃ OH HSO ₄ ) and 18 percent by weight of ammonium sulfate ([NH ₄ ] ₂ SO ₄ ), corresponding to 12 g or 0.35 mol of NH ₃ OH ⁺ (1.06 mol of NH ₃ OH per mol of uranium in the solution), is added. The hydroxylamine solution has been previously heated to 100 "C and is added in four separate portions of 100, 65, 40 and 20 ml at 3.5 minute intervals. In this way a concentration of at least about 0.07 mol per liter of NH is obtained ₃ OH ⁺ in the solution during the precipitation of 86.5% of the uranium (see Table 1 below) After the first addition, the reaction is rapid, resulting in precipitation of crystalline NH ₄ UF ₅ and consumption of hydroxylamine according to the equation

UO ₂ F ₂ + 2HF + NH ₄ F + NH ₃ OH 'Cu'

NH ₄ UF ₅

1 / 2N ₂ O he

+ 2 -1 / 2H ₂ O + H ⁴

caused.

The first addition of HK) ml of the hydroxylamine solution produces an absorption concentration of NH ₃ OIP of approximately 0.34 mol / l, this (15 concentration during the 3.4-minute period during the next addition to approximately 0.09 Mol / l sinl After the second addition (65 ml) the concentration in NH ₃ OH ^{+ increases} momentarily to 0.28 Mo

109635/2

and then drops to about 0.08 mol / L over the next 3.5 minutes. After the third addition (40 ml) the NH ₃ OH ⁺ concentration increases momentarily to 0.19 mol / l and then falls again to approximately 0.08 mol / l in 3.5 minutes. The last encore

of 20 ml brings the concentration of NH ₃ OH ⁺ momentarily to 0.13 mol / l, this concentration gradually falling to 0 over the next 5 to 10 minutes. The progress of the reaction is shown in Table 1 below.

Table I.

Encore

1.
2.
3.
4th

Total mole

Moles of NH ₃ OH ⁺
per Mon! U

0.472
0.306
0.188
0.094
1.06

Time in minutes

3.2 to 3.5

3.5 to 7.0

7.0 to 10.5

10.5 to 11.2

11.2 to 16.0 NH ₃ OIl ^ concentration

Moles / i

0.34 to 0.09
0.28 to 0.08
0.19 to 0.08
0.13 to 0.10
0.100 to 00

% Conversion to

NH ₄ UF ₅ after expiry

the time span

34.3
63.5
84.0
86.5
100.0

The green crystalline precipitate obtained is separated off from the mother liquor by filtration, a liquid being obtained which contains 80 ppm of uranium, based on the metal. This corresponds to a yield of approximately 99.95% based on the uranium in the ore concentrate. The crystalline NH ₄ UF ₅ product is dried at 120 ° C. and analyzed. A spectrographic analysis shows a purity of 99.8%, the separation of the elements Na, K, V and Mo, which were initially present in the ore concentrate, is as follows:

Table II

35

pollution

, [Concentration in parts per million parts of U ore concentrate [NH _t UFj product

'3000

200

300

300
80

4th
10

40

45

An analysis of the NH ₄ UF ₅ by X-ray diffraction shows that its crystal form consists essentially of the α structure since its pattern shows strong diffraction peaks at d-values of 8.4, 3.49, 3.03 and 2.13 Å , which are characteristic of U-NH ₄ UF ₅ so, while only weak peaks occur at the d- values 6.97, 4.01, 3.48, 3.24 and 2.02 A, which are characteristic of the 0- Shape are. In addition, no diffraction peaks at the d · values 7.68, 3.19, 2.42, 2.22, 2.11, 2.07 and 2.00 Å, which are characteristic of _{the compound NH 3} OHUF, are found .

Example 2

606 g of a composite ore concentrate of the same kind as described in Example 1, dai 74,9VeU (corresponding to 454 g or 1.91 mole of uranium in the form of metal) which are at 1.41 Waiter in a 3,8- 1-vessel slurried. With stirring, 392 g of a 6s aqueous 48% hydrofluoric acid, corresponding to 4.9 moles of HF per mole of uranium in the heart, are added to this slurry with stirring.

now. The stirring is continued for about 10 minutes until the ore concentrate is essentially completely dissolved. In this manner, approximately 1.71 of a uranyl salt solution is formed which contains primarily UO ₂ F ₂ and an excess of dissolved HF along with minor amounts of impurities that are present with the uranium in the ore concentrate.

To the solution described above, 19 g of CuSO ₄ -SH ₂ O and then 33 ml of 37% hydrochloric acid are added, whereby a solution is obtained which contains approximately 3 g of Cu per liter. The molar ratio of HCl / Cu is approximately 5. Then 70 g of ammonium fluoride, corresponding to 1 mol of MH ₄ F per mol of uranium, are added to the solution.

The mixture produced in this way is then heated to 100 ° C. A total of 500 ml of a liquid is then added in portions, containing 25.1% (NH ₃ OH) ₂ SO ₄ and 26.8% ( _{NH 2} SO ₄ based on weight containing. These mixes corresponding to 70 g or 2.06 MoINH ₃ OH ⁺ (ie 1.08 Mo 'NH ₃ OH ⁺ per mole of uranium). The liquid is pre-heated to 100 ⁰ C and added in five separate Portioncr, ie in five 100 ml portions to Begini and added every 3 minutes until the total addition of 500 ml is made. After the first addition, the reaction occurs quickly, causing precipitation of crystalline NH ₄ UF ₅ and consumption of hydroxylamine.

The first addition of 100 ml of the hydroxylamine liquid produces an initial concentration of about 0.23 mol / l NH ₃ OH ⁺ , while the following additions result in slightly smaller momentary increases in the NHjOH ⁺ concentration due to the dilution by the hydroxylamine liquid itself so that after the fifth and last addition the instantaneous increase is about 0.18 mol /. During each 3-minute period, the NH ₃ OH ⁺ concentration falls to a fraction of the concentration present at the beginning of these periods of time, the fraction being in accordance with the kinetics of the above reaction , which is proportional to the UO ₂ F ₂ concentration fluctuates.

The approximate NH ₃ OH ⁺ concentration true of the five FlUssigkeitazugaben are as follows:

11th 1803 344 -p 12th Table IH Hydroxylamine Concentration
Minor % Conversion to
NH ₄ UF ₅ after expiry Time in minutes the time span Clogged mole
NH ₁ OH ⁺ per MoI U 0.23 to 0.06 18.0 in be O to 3 0.28 to 0.08 35.0 0.216 3 to 6.0 0.29 to 0.11 53.0 1. 0.216 6.0 to 9.0 0.31 to 0.15 70.0 2, 0.216 9.0 to 12.0 0.34 to 0.18 85.0 3. 0.216 12.0 to 15 0.18 to 0.10 92.0 4th 0.216 15 to 16.7 0.10 to 00 99.8 5. 16.7 to 20

From Table III it can be seen that of the total of almost 100% conversion over 90% then can be achieved when the hydroxylamine concentration is above 0.07 mol per liter, while less than 10% of conversion at concentrations below 0.07 moles per liter after completion the reaction take place.

The resulting green crystalline precipitate is separated from the mother liquor by filtration to give a liquid containing approximately 50 parts per million parts of uranium on a metal basis. This corresponds to a yield of 99.8% of the uranium contained in the ore concentrate. The crystalline NH ₄ UF ₅ product is ^{dried at 120 °} C. (667 g = 1.90 mol are obtained) and analyzed. Spectrographic analysis shows a purity of 99.8%. The elements Na, K and other elements that are present in the ore concentration or in the end product are present in the following quantities:

Table IV pollution Contamination in
that together
set ore,
Parts per million
Parts U *) ND - ■ Not detectable. pollution
by doing
NH..UF, product,
Parts per million
Parts U N / A 5000 400 K 1000 100 Fe HMX) 300 Mn 800 ND *) Si 300 40 Cu 50 80 Ni 50 ND *) Approx 400 40 Cr 70 ND *) B. 20th ND *) Ti 200 3 V .... 2 (XX) 20th Mon 5 (X) 6th

From the above table IV it can be seen that the NH ₄ UF ₅ crystallized out in the η-form contains only very few impurities and the impurities contained in the original material are largely in the conversion of the uranyl salt into the a-ammomumuran ( IV) pentafluoride must be switched off.

Analysis of the NH ₄ UF ₅ by X-ray diffraction shows that its crystal form consists essentially of the α structure, since its pattern has strong diffraction peaks at the tf values of 8.4, 3.49, 3.03 and 2.13 Å, which are characteristic of the a-NH ₄ UF ₅ shows, while only weak peaks at the d values 6.97, 4.01, 3.48, 3.24 and 2.02 A, which door the / J- Shape are characteristic. In addition, there are no diffraction peaks at d-values of 7.68, 3.19, 2.42, 2.22, 2.11, 2.07 and 2.00. These values are characteristic of the compound NH ₃ OHUF ₅ .

Example 3

100 g of a uranium ore concentrate, which is similar to the ore described in Example 1 and contains 73.8% U (corresponding to 73.8 g or 0.31 mol of uranium as metal), are mixed with 200 ml of water in a corrosion-resistant ll- »carbate« - Vessel (impregnated with graphite) slurried. 55 ml (corresponding to 62 g) of an aqueous 48% HF solution containing 29.8 g of HF corresponding to 4.8 mol of HF per mol of uranium in the ore are added to this slurry with stirring. Stirring is continued for approximately 10 minutes until the ore concentrate is essentially completely dissolved. In this way a uranyl salt solution is obtained which mainly contains UO ₂ F ₂ with an excess of dissolved HF together with minor amounts of impurities which are present with the uranium in the ore concentrate.

3 g of copper sulfate pentahydrate (CuSO ₄ 5H ₂ O) and then 4 ml of a 37% HCl solution are added to the solution described above. In this way a solution is obtained which contains about 2.5 g Cu per liter, the molar ratio HCl / Cu amounts to about. 4 Then 12 g of ammonium fluoride, corresponding to 1 Mo NH ₄ F per mole of uranium, are added to the solution.

The mixture produced in this way is then heated to 100 ° C , whereupon a total of 23 | Acctoxime, (CH ₃ ) ₂ CNOH corresponding to 10.5 g or 0.31 Mo! Hydroxylamine (ie 1.00 mol of hydroxyl am in per mole of uranium) can be added in separate portions . The portions are added in terms of weight and the frequency with which a concentration of approximately 0.07 McNH ₃ OH ⁺ per liter of solution is maintained until 91% of the uranium in the solution has been converted to NILUF. Specifically , the Acetoxitn is served in eight portions of approximately 3 g portions, each at 2 minute intervals

added until the total addition of 23 g has been made. The reaction occurs quickly after the first addition of the acetoxime. thereby causing precipitation of crystalline NH ₄ L ¹ F- "and consumption of hydroxylamine.

The initial addition of 3 g of acetoxime produces an instantaneous concentration of approximately 0.15 mol per liter of hydroxylamine, while each subsequent addition increases the hydroxylamine concentration by approximately 0.15 mol. During each 2-minute period, the concentration is reduced to a fraction of the concentrations present at the beginning of the individual periods, the reduction in kinetics corresponding to the reaction (!), Which varies _{proportionally to the UO 2} F _{: concentration.} The approximate NH, OH '' concentrations during the eight acetoxime additions are given in Table V:

Table V

Encore

1.

3.
4th
5.
6th
7th
8th.

Zcii in Minutes 2 0 until 4th 2 until 6th 4th until 8th 6th until 10 8th until 12th H) until 14th 12th until 16.8 14th until 20th 16.8 until

Moles of NH ₃ (JH "per mole of U

0.1305 0.1305 0.1-305 0.1305 0.1305 0.1305 0.1305 0.0865 Hyclroxyluminkon / cnU'ilion
Minor

0.15 to 0.05
0.20 to 0.07
0.22 to 0.09
0.24 to 0.11
0.26 to 0.13
0.28 to 0.15
0.30 to 0.18
0.28 to 0.10
0.10 to 00

% Conversion to
I ₄ UI ⁷ ; after the time has elapsed

10.0
20.5
33.6
42.0
52.4
63.5
73.3
87.2
100.0

The green crystalline precipitate obtained is separated from the mother liquor by filtration, yielding a liquid containing 50 parts per million parts of uranium in terms of metal. This corresponds to a yield of 99.98% of the uranium contained in the ore concentrate. The crystalline NH ₄ UF <product is dried at 120 "C and analyzed. Line spectrographic analysis shows a purity of 99.8%, whereby it is found that the elements Na, K, V and Mo, which were present as impurities, are as stated Table VI below shows that the concentrations of these elements in the ore concentrate and in the end product are given in the table.

Table Vl pollution Concentration in parts per I millionTcilc U

Ore concentrate

24,000 1500 7 (X) 100 500 40 20th 4th

NH «UFj product

The analysis of the NH ₄ UF ₅ by X-ray diffraction shows that its crystal form consists essentially of the α structure, and that its pattern shows strong diffraction packets at the ii values of 8.4, 3.49, 3.03 and 2.13 A. which are characteristic of W-NH ₄ UFj. Only weak peaks are found at the rf values 6.97.4.01.3.48.3.24 and 2.02 A, which are characteristic of the / I form. In addition, no diffraction packs were found at the d-values 7.68, 3.19, 2.42, 2.22, 2.11, 2.07 and 2.00 . These values are characteristic of the compound NH ₃ OH UF ₅ .

Example 4

Two 100 g servings of an ore concentrate with high sodium and uranium oxide content. the 66.5% uranium and 3.0% sodium (30,000 parts per 1 million Parts U) along with other minor amounts of impurities such as 0.3% K

(3000 ppm), are suspended separately in water and an excess of HF in the amounts specified in the previous Examples 1 to 3. The essentially clear solutions obtained, mainly UO ₂ F, with excess

If they contain dissolved HF, 4 g of CuSO ₄ -5H ₂ O, 5 ml of 37% hydrochloric acid and 12 g of NH ₄ F are added.

Each of the two identical solutions thus formed becomes an aqueous solution of

Hydroxylamine and ammonium sulfate and bisuirate (see Example 1) added, but according to methods which differ from the method described in example 1:

A. 500 ml of the hydroxyl amine solution are added to the first solution at once in a single charge (corresponding to about 2.20 mol ₁ NHjOH ⁺ pn mol uranium), whereupon the mixture is ^{heated to 0} C and at this temperature ins

held for a total of 20 minutes. During this time the hydroxylamine concentration is always kept essentially above 0.07 mol pn liter, namely between 0.90 mol per liter immediately after the addition of the single batch down to 0.17 mol after 8.5 minutes. At this point practically all of the uranium in the solution has been converted to NH ₄ UF.

B. The second solution is a total of 250 m of the hydroxylamine solution (corresponding to 1.05 Mc NHjOH * per mole of uranium) at KXVC in Horn of a continuous stream with a Flicli speed of about 12.5 ml per Wed

(> o

<> s

zero for a period of 20 minutes. At the end of this period, practically all of the uranium in the solution is converted to NH ₄ IJr ₅ . Throughout the period, the concentration of the hydroxyl imine in the solution is always significantly less than 0.07 mole per line, and varies from less than about 0.01 mole per liter to about 0.027 mole per line.

The progress of the reactions is shown in Tables VI-A and VIl-B .

Table VI-A

Encore Time in minutes Added moles of NH ₁ OII '
per mole of IJ NHjOir concentration
Minor % Conversion to
NH ₄ UP ₉ after completion
the time span small addition 0 2.20 0.0 to 0.9 1 to 2 0 0.9 to 0.75 27 2 to 3 0 0.75 to 0.61 49 3 to 4 0 0.61 to 0.49 67 4 to 5 0 0.49 to 0.39 80 5 to 6 0 0.39 to 0.31 90 6 to 7 0 0.31 to 0.25 95 7 to 8.5 0 0.25 to 0.17 99.95 + Total NH ₃ OH ⁺ 2.20

Table VIl-B

Encore Time in minutes Added moles of NH ₃ OH ⁴
per mole of U NH ₃ OH ^ concentration
Minor % Conversion to
NH ₄ UF ₃ after completion
the time span Continuously in an even a lot of 0.0575 moles per minute 0 to 1 0.0575 <0.01 5.4 I to 3 0.1150 <0.01 22.2 3 to 5 0.1150 <0.01 28.0 5 to 7 0.1150 <0, () l 38.5 7 to 10 0.1725 <0.01 to 0.01 54.0 10 to 15 0.2875 0.01 to 0.015 77.5 15 to 18 0.1725 0.015 to 0.020 91.5 18 to 20 0.1150 0.020 to 0.027 99.95 + Total NH ₃ OH ⁺ 1.150

The green crystalline precipitates obtained are carried by their corresponding mother liquors Filtration separated, whereby liquids are obtained, which in both cases 50 ppm or less uranium (as U) included. This corresponds to yields of more than 99.95%, based on the uranium in the ore concentrate. The products have a similar physical appearance and appearance in both cases filter easily in the same way.

The crystalline NH ₄ UF ₅ products are dried at 120.degree. C. and analyzed.

The X-ray diffraction analyzes show how the following explanations will show considerable differences in terms of the crystal shape:

X-ray imaging analysis

The product A was chosen mainly from (! -NH ₄ UFs with considerable amounts of NH ₁ OIH) I ',, (20 to 40 "' ii). As from the strong adjustment packs at the d- values 8.4, 2.49 , 3.03 and 2.13 A. These values are characteristic of U-NH ₄ UF _5. There are somewhat weaker peaks at d values of 7.68, 3.19, 2.42, 2.22, 2 , 11, 2.07 and 2.00 Å. These values are characteristic of the compound NH ₃ OHUF _5. No peaks are found for d values

of 6.97, 4.01, 3.48, 3.24 and 2.02 Å. These values are characteristic of / J-NH ₄ UF ₅ . This shows that practically no / J-NH ₄ UF ₅ is present.

Product B consists mainly of

(io measured from / J-NH ₄ UF ₅ , as from the strong diffraction peaks at d-values of 6.97, 4.01, 3.48, 3.24 and

2.02 Ä can be seen. These values are characteristic of / (- NH ₄ UF _5. With d-values of 8.4, 3.49,

3.03 and 2.13 A are very weak peaks fcst- <> s. These peaks are characteristic of H-NH ₄ UF ₅ . There is no evidence of peaks which are characteristic of the compound NHjOHlJF ₅ .

Speklrogruphisuhc analyzes /. Own the substantial Difference in the elimination of sodium and potassium in the «- and // - crystals (cf. the following Table VIII).

Table VIII

a time span of 22.5 minutes, d. H. from 2.5 to 25.0 minutes, set:

pollution

N / A
K.

Concentration in parts per million parts I.

original Hr / kon / enlrut

30 (K) O
300

M-NH ₄ IJIv the product (A)

«(X) 200

/ (- NII ₄ UIv l'roilukl (U)

9000 2 (MM)

IS

From Table VIII above, it can be seen that the crystalline form of ammonium uranium (IV) fluoride retains significant amounts of the impurities originally present in the ore and uranyl brine, as opposed to the crystalline alpha form. It can also be seen that the process according to the invention _{is suitable for the production of U-NH 4} UF ₃ with very low sodium and potassium impurities. This NH ₄ UF ₅ is suitable for the production of UF ₄ in a fluidized bed. One can also assume extremely heavily polluted uranium ores and uranyl salt solutions. If the / 3 salt is produced from the same ore and from the same uranyl salt solution, it is heavily contaminated with sodium and potassium, so that it is not suitable for the production of UF ₄ in a fluidized bed.

Zuiiinicrviill ml in /ujjcscl/.ler Minulen j,,. ₄ ssK 2.5 to 5.0 10.1 5.0 to 7.5 9.3 7.5 to 10.0 8.5 10.0 to 12.5 7.7 12.5 to 15.0 6.9 15.0 to 17.5 6.3 17.5 to 20.0 5.5 20.0 to 22.5 4.7 22.5 to 25.0 4.0

63JT

Example 5

35

100 g of an ore concentrate containing 78.5% U (corresponding to 78 ^ 5 g or 0.33 mol uranium as metal) is mixed with water, 48% HF, CuSO ₄ · 5 H ₂ O, 37% HCl and NH ₄ F in the same amounts as given in Example 1 treated.

The mixture is heated to 10O ⁰ C, after which 84 ml are added to a liquid, the 25.1 weight percent (NH ₃ OH) ₂ SO ₄ and 26.8 percent by weight of (NH ₄ J ₂ SO _4, corresponding to 11.4g or 0.383 MoI NH ₃ OH ⁺ ie 1.16MoI NH ₃ OH ⁺ ^ per mole of uranium in the batch. The addition takes place in the following way:

step 1

21 ml of the liquid (which contains 2.85 g or 0.0865 mol of NH ₃ OH ⁺ ) is added all at once, so that an initial concentration of 0.227 mol / l of NH ₃ OH ^{+ is set} in the solution. This concentration has dropped to 0.080 mol / l in 2.5 minutes.

' Level 2

Immediately after the end of the 2.5-minute period of stage 1, the remaining 63 ml of the fio Hydfoxylaminulfatlösung (corresponding to 8.55 g or 0.2965 MoI NH ₃ OH ^f ) in the form of a continuous stream from a burette with a steadily decreasing Speed added. The speed is determined from kinetic values that are available for this reaction system. A constant concentration of [NH ₃ OH ') of 0.080 mol / l in the solution is thereby obtained. _{At the end of stage 2, the reaction mixture is quickly filtered to separate off the precipitated NH 4 UFj.} The product is washed and dried at 120 ° C. The amount of NH ₄ UF _{5 obtained} is 101.2 g, which corresponds to a recovery of 87% of the uranium in the ore concentrate.

An X-ray diffraction analysis of the product obtained shows that it consists of practically pure (J-NH ₄ UF _5. This is evident from the very strong diffraction peaks at rf values 8.4, 3.49, 3.03 and 2.13 Å . These values are characteristic of the «crystals. No peaks are found at one of the d values 6.97, 4.01, 3.48, 3.24 or 2.02 A. These values are characteristic of the / / Crystals.

level 3

Immediately after the separation of the precipitated NH ₄ UF ₅ described above, the filtrate (which _{begins to develop a further NH 4} UF ₅ precipitate during the filtration) is ^{heated again to 100 °} C. and kept at this temperature for a period of 10 minutes, until the rest of the uranium has precipitated. During this stage, the [NH ₃ OH ^ concentration determined falls continuously from 0.080 mol / l to below 0.03 mol / l.

The precipitated NH ₄ UF ₅ is separated off, washed and dried at 120 ° C. 15.7 g of the product are obtained (which corresponds to approximately 13% of the uranium in the ore concentrate).

An X-ray diffraction analysis of the product from stage 3 shows that the product consists predominantly of // - NH ₄ UF ₅ . This is evident from the very strong diffraction peaks at d values of 6.97, 4.01, 3.48, 3.24 or 2.02 A. These values are characteristic of the // form. Practically no peaks at ii values, which are characteristic of the u-shape, are found.

It can be seen from this that maintaining the hydroxylamine concentration in the solution at a value of 0.08 mol per liier results in precipitation of NH ₄ UF ₅ exclusively in the crystalline n-form.

The following table IX shows a comparison of the elimination of the impurities in the production of NH ₄ UF ₁ with Liiiiliiilltmi ^{1 of} the erliniluiig.igetiuil.ien process, with v.eldn'ni ilie crystalline n-form er / eiigl

/ IΛ

(Example I) is given to the considerable retention of the impurities when carrying out a process in which the crystalline form is formed (Example 4B) ₁ where ore concentrates and uranyl salt solutions are used as Ausgungsmuteriulicn, which initially contain different amounts of such impurities. Since in all cases the amounts of impurities are given in parts of the impurity (as metal) per million parts of uranium (as metal), the values given for the ι ο ore concentrate reflect the proportions of the impurities in the uranium salt. In a similar way, the amounts of impurities shown for the ammonium uranium pentalluoride product can also be transferred to uranium tetrafluoride (UF ₄ ), which is ultimately produced from the NH ₄ UF ₅ by pyrolysis.

η parts per Million Shares : U - 9 Table IX Erzkonzcnlral Example I. Example 41 20th 2 uikI Urunylsal / -
solution ..- NM ₄ UF ₅
plus trace • / 1-NII ₄ UF ₅
plus trace - 4000 Products and metallic impurities // - NIl ₄ UF, .1-NM ₄ UF ₅ 1,000 30,000 2000 9,000 - 24,000 1,500 8000 600 Ver
ruin 5,000 400 - HX) 3,000 300 100 70 N / A 1,000 - - 3 (XX) 200 2 0 (X) <40 1000 H) O - 700 100 200 <40 300 - - K 200 - <80 70 2000 20th -30 - 500 20th JO 40 4th 4th 30th - V 800 20th 500 6th 70 10 20th - Mon 10,000 _: - 4000 2000 2000 - 1,000 300 Fe 1 (XX) HX) 8 (X) ND *) 2 (X) K) (XX) <4 () Mn 5 (XX) <4 () 1 (XX) 3 (X) <-K! Si 200 70 ND *) <20 ND *) 200 1 Cr 1! Ti

35

40

45

55 The founding process enables the production of ammonium uranium (IV) pentufluoride in very high bulges as well as in very high purities and uranium ore concentrates of varying grades. The process enables the use of ore concentrates with relatively high levels of un detrimental impurities such as nairium, potassium, molybdenum and vanadium. In this way, the use of ore concentrates is possible which previously could not be used to remove these impurities without further treatment.

Claims (6)

Patent claims: 1. A process for the production of crystalline ammonium uranium (IV) pentafluoride, characterized in that that at a temperature of at least 85 "C hydrogen fluoride, hydroxylamine or a hydroxylamine-donating compound and an aqueous solution of a uranyl salt which Contains chloride, copper (II) and ammonium ions, be brought to reaction, the concentration of hydroxylamine being either from such or in the form of a hydroxylamine-supplying compound is present in the 1 ösung at least 0.07 moles per liter of solution is maintained until at least 75% of the 1 'ins in crystalline ammonium uranium (IV) -pentafluond converted have been. 2. The method according to claim 1, characterized in that that the hydroxylamine or the hydroxy 1-amine supplying compound in portions during the course of the reaction in a total amount of 1.0 to 1.5 moles per mole of uranium and in one such a rate is added that the concentration of hydroxylamine that either as such or in the form of a hydroxylamine-donating compound, between 0.07 and maintaining 0.50 moles per liter of the solution until at least 75% of the uranium is crystalline Ammonium uranium (IV) pentafluoride have been converted. 3. The method according to claim 1 or 2, characterized in that the molar ratio of chloride ions to copper (II) ions is at least 4: 1, the amount of hydrogen fluoride used is at least sufficient to remove all of the uranium present in ammonium uranium (IV) -pen1 To convert afluoride, at least 0.03 moles of Cu ⁺⁺ ions per liter of the solution are used and at least 1 mole and preferably 1 to 1.5 moles of ammonium ions are used per mole of uranium. 4. The method according to any one of the preceding claims, characterized in that UO ₂ F _{2 is used} as the uranyl salt. 5. The method according to any one of the preceding claims, characterized in that the hydroxylamine is added as the oxime or as the hydroxylamine salt. 6. The method according to any one of the preceding claims, characterized in that the Urrfsei / ung between hydrogen fluoride, hydroxylamine or hydroxylamine supplying compound and chloride, copper (II) - and ammonium ions containing urunylsal / Iösung at a temperature in the range of ¹ > 5 to 105'C is carried out.