DE1542179B1 - Process for the production of compact metal oxide or metal carbide microspheres - Google Patents

Description

1 2

The present invention relates to a method for large amounts of soluble metal salts are so in the production of compact metal oxide or metal previously known method for the production of carbide microspheres by dropping a uranium microspheres by solvent dehydration as dioxide, uranium trioxide, thorium dioxide, Plutonium raw material completely unsuitable,
Dioxy, plutonium trioxide, zirconium dioxide, beryllium 5 The object of the present invention is the simple oxide, yttrium oxide aquasols or a mixture of such compact microspheres that are used in the production of metal carbide micro-cores that are no longer the. Above mentioned disadvantages show up to 5 moles of colloidal carbon per mole. i'f _; .,
Contains metal, in a dehydrating solvent, to solve this problem, the invention consists of isolating the dehydrated microspheres from the ent- ίο of a process for the f ^ sKtelluög of compact watering solvents and possibly sintered metal oxide or metal carm ^ microspheres through Dropping in of uranium dioxide, uranium trioxide, thorium. For nuclear reactor fuel elements, metal dioxide, plutonium dioxide, plutonium trioxide and zirconia compounds are required, to which actinide compounds include kondioxide, beryllium oxide, yttrium oxide, thorium dioxide, uranium dioxide - 15 or a mixture thereof, in the production of the dioxide, plutonium dioxide and plutonium trioxide, metal carbides with up to 5 moles of colloidal carbon thinning oxides such as zirconium dioxide, yttrium oxide and substance per mole of metal, in a dehydrating solvent, beryllium oxide and the isolation of these metal oxides of the dehydrated microspheres made from the corresponding metal carbide. aqueous solvents and optionally sintering-die metal cations of said actinidene oxides. The invention is characterized in that and diluting oxides are U ⁺⁴ , (UO ₂ ) + ² , Th ⁺⁴ , the Aquasol with an ammonia-releasing Pu + ⁴ , (PuO ₂ ) + ² , (ZrO) + ² , Be + ² and Y + ³ . Agents mixed and the mixture in a dehydrating-tight microspheres from these oxides alone or the solvent, the temperature of which is sufficient for a combination with other metal oxides and / or extensive decomposition of the ammonia-releasing carbon in the size range of 50 to 200 microns 25 agent.

are for the production of fuel assemblies for high- In the Aquasol, up to the saturation concentration

temperature nuclear reactors such as gasification one or more salts of one or more

cooled reactors important. Such microspheres contain metal cations U + ⁴ , (UO ₂ ) + ² , Th + ⁴ , Pu + ⁴ , (PuO ₂ ) + ² ,

are made up of two parts, a core and a supernatant Be + ² and Y + ^s dissolved and optionally up to 5 mol

train. The core part contains the actinidene oxide, either 30 colloidal carbon per mole contained in the Aquasol-

alone or in solid solution with another oxide. be dispersed in a metal.

The core can also be formed from an actinidene carbide and carbon can be formed from an actinidene carbide as the starting material. For the process according to the invention, the core must be micro, have a good spherical shape, strength and high density on spheres of high quality, which are proven by the. For fission product retention, the core made with known processes is by far superior to an impermeable coating made of refractory, and in addition, working conditions are widespread within substantially metal oxide or pyrolytically produced soot and oversight. The coated microspheres are then driven in much easier can be controlled
40 The dissolved metal salts in the aquasol used as the starting material correspond to the metal spheres desired in the microspheres to be produced in microspheres by dewatering aquasol droplets in oxides, ie they comprise metal salts with the catalysts Making solvent. In this process ionen U + ⁴ , (UO ₂ ) + ⁸ , Th + ⁴ , Pu + ⁴ , (PuO ₂ ) + ² , (ZrO) ⁺² , the sol droplets are in a dehydrating solution 45 Be + ² and Y ⁺³ , their Anions to determine water-soluble salts are injected and removed in dehydrated form from the type, such as the metal chlorides, bromides, solvents. Since this is a large volume nitrates, sulfates, formates and acetates; monovalent part of the droplets, ie water, has been removed, the anions are preferred.

Size of the droplets during dehydration strong. Some metal oxide aquasols contain due to the

decreased. The 5 ° obtained by this process used to prepare them

Microspheres often have holes, cracks and hollow metal salts. For example, uranium dioxide zirconia

tidy up inside. Through precise control of the condioxide aquasole by peptizing a lower

Although the proportion of damaged blow from water-containing uranium dioxide with a method can

Balls are reduced, however, this control is made of zirconyl salt, the obtained Aquasol

the process extremely difficult and results in 55 zirconyl salts in solution and on the surface of the

still contains a considerable proportion of harmful uranium dioxide micelles absorbed,

adhere to microspheres. In the same way, Aquasols are produced by peptides

In other known processes for the preparation of a metal oxide with a salt of the same

Made of metal microspheres by solvent drainage. With the inventive

If the starting material is based on metal oxide aquasols, high quality microspheres can be made

restricts. Incidentally, produce such aquasols contained in the aquasols.

Metal salts remain in soluble form in the micro- The method according to the invention also enables

balls. As a result, only very small quantities can produce microsphere cores from aquasols,

soluble metal salts in the for the production of the micro which are mixed with metal salt solutions to

spheres used Aquasols are approved and 65 an Aquasol with a content of dissolved metal salts

there have to be cumbersome procedures to avoid it. So can be according to this procedure

of losses of metal ions from the dewatered containing uniform metal oxide mixtures

Microspheres are carried out. Manufacture Aquasols with large microspheres from Aquasols, which contain oxide

Particles of a metal and dissolved salts of the same can fertilize the Aquasol, expressed as metal oxide,

or another metal. in the range from 1 to 500 g per liter and preferably

It is advantageous to use an Aquasol which is between 50 and 150 g per liter. The amount of

one or more dissolved salts of one or more of the dissolved metal salts in the Aquasol is preferably located

Metal cations U ⁺ *, (UOO ⁺² , Th ⁺⁴ , Pu ⁺⁴ , (PuOa) ⁺² , 5 between 0.1 g per liter and the highest not yet available

(ZrO) ⁺² and Y ⁺³ in amounts up to the saturation concentration level leading to flocculation. The ammonia

contains tration. dispensing agent is combined with the Aquasol in one

The concentration of metal compounds mixed in the amount which Aquasol used to form a metal as a starting material can vary in oxide gels from the metal-wide range contained in the Aquasol. So the overall concentration can be sufficient. If the metal oxide aquasol tration of metal compounds in the Aquasol, expressed is largely free of dissolved metal salts, between 1 and 500 g per liter and partly as much ammonia-releasing agent is added as the metal oxide, preferably between about 50 and 150 g per liter that the pH value of the Aquasol to a pH of 1.0 to 0.1. Dissolved metal salts can be contained in the Aquasols units below the gelation pH value of the sol, ranging from 0 to the saturation concentration. 15 represents. When the Aquasol is used in substantial quantities, it is said to contain "dissolved metal salts" if the liquid phase is saturated with soluble metal salts if the liquid phase is saturated with the solvent. The dissolved 300% of the metal salts required to precipitate the metal salts can be supplied in the Aquasol in amounts of over borrowed stoichiometric amounts of ammonia.
0.1 g per liter should be included. The metal salts used in the process according to the invention are preferably present in amounts which do not consist of the ammonia-releasing agents are generally sufficient to flocculate the sol particles, but mean from compounds which, when heated, can also lead to flocculation amounts of metal salts dissolved above room temperature by thermal decomposition Used in the starting material, emit significant amounts of ammonia when space becomes available. Under the name Metalloxydaquasole 25 temperature, however, are relatively stable. Due to their low reaction rate of metal and ammonia oxydaquasols, which do not contain any dissolved metal salts or release at room temperature, these compounds can also be added to metal oxide aquasols in less than amounts that lead to flocculation to the metal oxide aquasols against the salts dissolved at room temperature. without immediately producing a reaction leading to flocculation of the sol particles. If the Aquasol drops then contain sufficient amounts of dissolved metal salts through contact. By varying the concentration of the solution and the dehydrating solvent heated by the dehydrating solvent, these compounds decompose rapidly, increasing the amount of ammonia released into the dehydrating solvent. The ammonia reacts with the drops brought in, after dehydration, metal compounds in the aquasols and forms a metal oxide gel in microspheres of various sizes. The ammonia will be. the Aquasol is preferably un-

The production of metal carbide microspheres for indirect use in fuel assemblies for nuclear reactors before being added to the dehydrating solution. However, the ammonia-releasing substance has become very important recently. These agents can also be mixed with the microspheres several hours prior to use made from microspheres. The temperature is kept at the correct temperature,
According to the method can be used for the production of micro- The mixed with the starting aquasols amount of balls with a very intimate, uniform mixture of ammonia-releasing agent should advantageously be of metal oxide and carbon from metal oxide 45 such that it is sufficient to remove from the in the aquasols with a Content of dispersed metal compounds containing colloidal sol droplets are used in the case of Konlem carbon. The dispersed tact with the dehydrating solvent allow a metal-carbon-containing metal oxide aquasole to form oxydgel. Metal oxide aquasols, which are widely produced by various simple processes. are free of dissolved metal salts, commercially available finely divided carbon 50 mixed with as much ammonia-releasing agent (soot) is suitable. The dispersion of the carbon that the pH of the starting material on in the Aquasol can easily be done by adding 1.0 to 0.1 and preferably about 0.8 to 0.4 pH-Einman the carbon of the Aquasol or with the solution to be mixed is added to the solution to be mixed below the gelation pH value of the sol and is made with. Dispersed below the gelation pH of an ultrasonic mixer. Another method is the pH value, which method consists in gelling the carbon in the sol within 15 minutes of setting this pH value using an ultrasonic mixer or a mixer. If the starting aquasol is dispersed with high shear force in water and contains substantial amounts of dissolved metal salts, carbon suspension is then added to the Aquasol or the ammonia-releasing agent in an amount to be mixed with the Aquasol metal salt solution 60 which is 70 to 300% and preferably 100% . The dispersion of the carbon in the 150 ° / ₀ of the employed to precipitate the metal salts in the off Aquasol process is not critical starting material required stoichiometric amount table. Ammonia supplies.

The microspheres can be made from the metal oxide and inventive method the compounds hexa- 65 metal oxide-carbon aquasoles, which the am-

methylentetramine, acetamide, ammonium carbamate, monia-releasing agents contain using

Ammonium cyanate, urea and mixtures of a solvent column are produced as they are

same preferred. The total amount of metal compounds in German Offenlegungsschrift 1 542 157

5 6

and 1,542,158. In this system with saturation concentrations of water in one, the aquasol droplets will have a high column rising countercurrent out of the area from above in a high column that is permitted by the setting of drying conditions. Introduced at a solvency for hot dehydrating solvent. Water from about 1 to 30 ° / ₀ was satisfactory. The hot solvent heats the drops and results are achieved. Preferred solvents are a decomposition of the ammonia-releasing, for example, hexanol, ethylhexanol and ethylbutanol. By means of, and the released ammonia reacts with solvents with too high a water-dissolving power, the metal oxide sol particles and, if necessary, those with a certain water content from the dissolved metal salts can be returned to form the corresponding distillation vessel, whereby the oxide gel in the aqueous droplets. On their way io effective water dissolving power is decreased. So through the column down the drops are for example butanol, which is dehydrated in the heat. The dehydrated microspheres are collected at the solvency capacity for water of about 28 weight trays of the column, continuously showing percent, almost saturated with water in the leads, freed from solvent and introduced into the column before sintering. In contrast, ethylhexanol is further dried. 15 which in the heat a solvency for water of

The device consists of a high column of 4 to 6 percent by weight, in almost anhydrous

with a conical bottom in which the micro-shape is returned to the column. Hexanol, which

drop balls. The dehydrating solvent will have a solvency for water of 10 to in the heat

Introduced into the column from below and at the top, which has 11 percent by weight, has a water content

Column withdrawn. The sol can be used on various 20 from 3 to 6%.

The dehydrating solvent occurs in the form of drops in the top of the column. For example, a narrow tube or mean with a temperature of about 60 to 120 ⁰ C an injection needle with an inner diameter in the column and is used when leaving the column of 0.15 to 0.6 mm to the sol in about 10 to 40 ⁰ C cooled. This temperature is used to introduce the solvent and the preferred range is for the release of ammonia to form in the particles. Preferably, the needle is surrounded by aquasol droplets in most ammonia-releasing a larger capillary tube, which is ideal. In the case of ammonia-releasing agents, such as solvent is carried out and the sol is in urea, higher solvent temperatures in the same direction can be used with this solvent stream.

guided. In another mode of operation, the sol is in 30 It is advantageous to have the aquasol droplets in the column

a suitable solvent to a drop of generally to a water content of below

uniform size emulsion containing dispersive 50 ° / ₀ and preferably to dry at 25 ° / o. if

yed and the emulsion partially dehydrated the product obtained as a product through a suitable inlet

approximately device introduced into the column. The microspheres unreacted precipitant, am-

dehydrated microspheres are formed from the conical 35 monium salts and other neutralization products.

The bottom part of the column is withdrawn. hold, these must be removed before sintering.

In this process, the solvent for reuse of the microspheres with ammonia can be prepared by acting to fix the oxide components, then passed to a distillation vessel where the water is washed with water and finally removed from it in an inert. The distillation vessel serves as a 40 gas stream or dried under vacuum. Preferably a solvent reservoir for the system and the microspheres can be heated ^{slowly to 110 ° C. by setting the water removal and the distillation 40 during drying.} The microspheres obtained can be temperature controlled so that there is a soldering can then be sintered.

supplies solvent with the desired water content. With the method according to the invention In the solvent supply line, a significant progress in the manufacture of material coolers for adjusting the solvent to the materials for nuclear reactor fuel assemblies can be achieved. In early wished Temperature. Hexamethylenetetramine was used to attempt this driving has the advantage that the conditions in the production of thorium oxide gels from thorium column can be varied over a wide range. nitrate used. However, it was found that the

A gel that is suitable for the process according to the invention is produced in this way for several hours

Apparatus consists of a 178 cm column standing converted back into brine. With further

Height and 7.6 cm in diameter with a conical bottom own preliminary tests was hexamethylenetetramine

to catch the settling microspheres. with previously prepared thorium oxide aquasols for

The solvent is mixed 10.2 cm above the column making gel beads. This method

bottom pumped into the column and 10.2 cm below the 55 has a number of significant difficulties

The top of the column is discharged from the column. which are not in the method according to the invention

The choice of solvent for this system is incurred. So the gel beads obtained were not very important. The best results are obtained with the watered and of low strength, so that their hand-higher alcohols with the desired solvency are associated with considerable difficulties for water. The solvent should be inert 60. The drainage took place only after the pearls, which had no undesirable physical properties, had been formed, separated and introduced into a separate direction, such as, for example, tendency to emulsify. Finally, one that allows the microspheres to settle does not have such a uniform size and surface area and low density and cannot be heated to a temperature as high as the density of the microspheres as that achieved for the decomposition of the ammo according to the invention ,
The process according to the invention represents a simple aqueous drop process introduced into this system. Since the rate of hydrolysis is sufficient. In addition, the selected ammonia-releasing agents must vary with the temperature

increases, these agents can be used at room temperature, where the rate of hydrolysis is very slow and no precipitation has yet been effected in which Aquasol are dissolved. If those containing the precipitant Aquasole will then be exposed to the higher temperatures of the dehydrating solvent the ammonia release is significantly accelerated and the water-containing oxide is precipitated in the droplets. By the dehydrating solvent is gradually extracted from the precipitated drops until water is largely extracted dry microspheres can be obtained.

The invention is illustrated in more detail by the following examples, but is not restricted to the same.

example 1
Manufacture of thorium dioxide microspheres

To produce a thorium dioxide sol with a thorium dioxide content of 15.5 percent by weight, aqueous thorium dioxide was precipitated with ammonia, the precipitate was washed free of electrolytes with aqueous ammonia solution and then with water, then nitric acid was added to lower the pH value and finally to form a sol heated to about 100 ⁰ C. Of this sol, 4.0 g of hexamethylenetetramine were added to 190 ml with vigorous stirring. The mixture had a pH of 4.0.

The hexamethylenetetramine treated sol was injected through a 23 gauge hypodermic needle, which was surrounded by a 2.8 mm wide capillary through which a stream of hexanol in the same direction flowed, injected into the head of a 213 cm high column, through which hexanol in countercurrent was pumped. The conditions in the column were as follows:

So injection rate 2.6 ml / min

Flow rate of the solvent

to the needle 110 ml / min

to the column 690 ml / min

Temperature of the solvent

to the needle 28 ° C

to the column 10O ⁰ C

from the column 74 ⁰ C

^{110 0} C in the distillation vessel

The microspheres collected on the column bottom were concentrated for about 15 minutes dipped aqueous ammonium hydroxide solution, washed free of electrolytes with water and dried.

The particles obtained consisted of smooth microspheres 150 to 250 microns in size. From the The same sol had microspheres produced under the same conditions but without hexamethylenetetramine had an irregular shape and deep holes, and were often broken. By adding Hexamethylenetetramine to the starting sol, the spherical shape of the particles was improved and the hole and fracture formation is significantly reduced.

Example 2
Manufacture of uranium dioxide microspheres

To produce a uranium dioxide sol, a uranyl chloride solution was electrolytically reduced to the corresponding uranium IV salt and the chloride ions were then removed by electrodialysis. The temperature of the system was 40 ^° C. in both processes. The sol obtained had an equilibrium pH of 2.5 and a specific conductivity of 3.2 × 10 ^-3 Ω- ¹ × cm- ¹ . The size of the uranium dioxide micelles was determined by an electron microscope The sol concentration was 95.8 g UO ₂ per liter of sol.
Part of this sol was left without further treatment

ίο injected into the column described in Example 1. A second part of the sol was mixed with so much hexamethylenetetramine that its pH value was 4.4 fraud. For the addition of the hexamethylenetetramine, 12.0 g of hexamethylenetetramine in 50 ml of water were used dissolved and this solution mixed with 50 ml of the sol.

The two sol samples, with and without hexamethylene

tetramine treatment, was passed through the column in sequence. The conditions in the column were the same in both cases, namely:

Sol injection rate 2.7 ml / min

Flow rate of the solvent

to the needle 100 ml / min

to the column 750 ml / min

Temperature of the solvent

to the needle 4O ⁰ C

to the column 95 ⁰ C

from the column 7O ⁰ C

^{108 0} C in the distillation vessel

The microspheres were treated with ammonia as in Example 1, washed and dried.

The sol that was not treated with hexamethylenetetramine only became microspheres obtained with deep holes while using the hexamethylenetetramine treated Sols microspheres perfect in every respect were obtained. The latter had a shiny black surface and no pitting or distortion of the shape. Both brines became Microspheres 150 to 300 microns in size were obtained.

Example 3

Manufacture of microspheres
with two metal oxide components

(Uranium dioxide and zirconium dioxide)

To prepare the sol, the corresponding hydrous oxides were precipitated together in a UO ₂ : ZrO ₂ weight ratio of 4: 1. The precipitate was washed free of electrolytes with dilute ammonia solution and water and then peptized to a sol by lowering the pH with nitric acid and the acidified sol was heated to reflux temperature for 1 hour. The sol had a pH of 1.5 and a specific conductivity of 3.0 x 10 ^-2 Ω- ¹ · cm ^"1. The micelle size of the sol was an average of 10 ηαμ.

A portion of the sol was mixed with 1.5 g of crystalline hexamethylenetetramine treated. This amount of hexamethylenetetramine became the pH of the sol brought to 4.1. Another part of the sol was not treated with hexamethylenetetramine.

009 546/406

The two sol samples, with and without hexamethylenetetramine treatment, was sent through the column under the following conditions:

Sol injection rate 2.0 ml / min

Flow rate of the solvent

to the needle 85 ml / min

to the column 700 ml / min

Temperature of the solvent

to the needle 30 ⁰ C

to the column 100 ⁰ C

from the column 75 ° C

^{110 0} C in the distillation vessel

The microspheres were treated with ammonia as in Example 1, washed and dried. the Microspheres made from the hexamethylenetetramine treated sol had a black glossy surface and no errors whatsoever. The microspheres from the one not treated with hexamethylenetetramine Sol showed deep holes and were largely broken or chipped. The microspheres out both sols were 100 to 250 microns in size.

B ei s ρ i e 1 4

Manufacture of uranium dioxide carbon microspheres

A uranium dioxide-carbon Aquasol with a molar ratio of carbon to uranium metal of 4.4: 1 was used as the starting material. The uranium dioxide sol used to prepare the starting material consisted of the sol described in Example 2. This sol contained 95.8 g of UO ₂ per liter of sol. The colloidal carbon dispersion used to prepare the starting material was prepared by dispersing colloidal carbon (carbon black) in 0.019 η ammonia solution containing a dispersant. A sodium salt of a polymerized alkylnaphthalenesulfonic acid was used as the dispersant. The carbon dispersion had a concentration of 9.76 weight percent carbon. The colloidal carbon used consisted of spherical particles with an average size of 55 μm.

To prepare the starting solution, 296 ml of the uranium dioxide sol were mixed with 57.2 g of the aqueous carbon dispersion. The carbon: uranium ratio 4.4 was chosen to achieve a uranium dicarbide after sintering. An excess of carbon was used because of the considerable loss of carbon on sintering by volatilization and reaction with oxygen. The uranium dioxide-carbon sol mixture had a pH of 2.6 and a specific conductivity of ³ 2,8-10- Q ¹ -C m. ¹

Part of this sol mixture was not treated with hexamethylenetetramine. Another part of the The mixture was mixed with so much hexamethylenetetramine solution that it had a pH of 4.0 would have. The hexamethylenetetramine solution was made by dissolving 12 g of crystalline hexamethylenetetramine obtained in 50 ml of water.

The untreated and the treated sol were passed through successively under the following conditions sent the column described in example 1:

Sol injection rate 4.0 ml / min

Flow rate of the solvent

to the needle 100 ml / min

to the column 750 ml / min

Temperature of the solvent

to the needle 40 ° C

to the column 95 ° C

from the column 74 ° C

112 ° C in the distillation vessel

The microspheres were as in Example 1 with

Treated with ammonia, washed and dried. The microspheres obtained from the untreated sol had deep holes. For the hexamethylenetetramine treated sol microspheres, the Holes completely disappeared. The microspheres obtained from both sols had a size im Range from 150 to 300 ιημ.

These microspheres can be converted into uranium dicarbide by sintering.

Example 5

Manufacture of uranium dioxide microspheres
from a dissolved uranium IV chloride

containing Aquasol

To prepare the starting material, a uranium dioxide sol was mixed with a uranium IV chloride solution. To produce the uranium dioxide sol, a uranyl chloride solution was electrolytically made into one Uranium IV chloride solution reduced, uranium dioxide precipitated from the solution with an aqueous ammonia solution, the precipitate washed free of electrolytes, dispersed in water, treated with 6 η sulfuric acid solution

acidified and the acidified uranium dioxide suspension heated to 100 ° C for 1 hour under nitrogen.

100 ml of the uranium dioxide sol obtained, which contained 100 g of UO ₂ per liter of suspension, were mixed with 211 ml of a uranium IV chloride solution of 95 g of UO ₂

mixed per liter corresponding concentration. Then a saturated solution of hexamethylenetetramine, which contained a total of 16.1 g of hexamethylenetetramine, with vigorous stirring to this Mixture given.

For the production of uranium dioxide microspheres, this sol was under the following conditions in the column described in example 1 injected:

Sol injection rate 2.3 ml / min

Flow rate of the solvent

to the needle 85 ml / min

to the column 690 ml / min

Temperature of the solvent

to the needle 29 ° C

to the column 100 ⁰ C

from the column 74 ⁰ C

^{112 0} C in the distillation vessel

The microspheres were treated with ammonia as in Example 1, washed and dried. The product consisted of perfectly black microspheres ranging in size from 115 to 250 microns. It is clear from this that the process according to the invention for the production of microspheres high quality from aquasols, which contain considerable amounts of dissolved metal salts, are used can be.

Example 6

Manufacture of microspheres

with two oxide components from a sol,

which due to the brine production process

contained dissolved metal salts

To produce a uranium dioxide-zirconium dioxide aquasol, freshly precipitated water-containing uranium dioxide was peptized with zirconyl nitrate solution. A uranyl chloride solution was electrolytically reduced to a uranium IV chloride solution. 1040 ml of this uranium IV chloride solution, which contained the equivalent of 50 g UO ₂ per liter, were mixed with aqueous ammonia solution to form a uranium dioxide precipitate. The water-containing uranium dioxide precipitate was filtered off and washed free of electrolytes. The washed precipitate was slurried with water to give 605 ml of suspension. 45 ml of zirconyl nitrate solution with a _{concentration corresponding to 287 g of ZrO 2} per liter were added to this uranium dioxide suspension while stirring. The mixture was heated to 100 ° C under nitrogen for 2 hours; a non-settling black sol was obtained.

4.4 g of crystalline hexamethylenetetramine were dissolved in 200 ml of this sol with vigorous stirring. The pH of the sol was increased from 1.7 to 4.0 by the hexamethylenetetramine. The sol was like in Example 1 used to manufacture microspheres.

The conditions in the column were as follows:

Sol injection rate 2.8 ml / min

Flow rate of the solvent

to the needle 90 ml / min

to the column 690 ml / min

Temperature of the solvent

to the needle 28 ° C

to the column 100 ⁰ C

from the column 73 ° C

^{108 0} C in the distillation vessel

As in Example 1, the microspheres were soaked in concentrated ammonia solution for about 15 minutes treated, washed free of electrolytes with water and dried.

Perfect microspheres were obtained. They had a black glossy surface and ranged in size from 100 to 250 microns.

Example 7

Production of uranium dioxide-zirconium dioxide-

Microspheres from a sol,

which was obtained by mixing a uranium dioxide aquasol with a zirconium salt solution

A uranium dioxide was produced in the same way as in Example 5, except that the uranium dioxide precipitate was acidified with nitric acid before peptization. Of this sol, which contained 61 g of UO ₂ per liter, 268 ml were mixed with 118 ml of a zirconyl nitrate solution with a concentration corresponding to _{287 g of ZrO 2 per liter.} The weight ratio UO ₂ : ZrO ₂ in this sol was 3.25: 10. To 100 ml of this Aquasol was added 2.0 hexamethylenetetramine solution obtained by dissolving 12 g of solid hexamethylenetetramine in 50 ml, whereby the pH of the sol was brought to 1.0.

From the Aquasol treated with hexamethylenetetramine, under the following conditions were as in example 1 microspheres produced:

Sol injection rate 2.5 ml / min

Flow rate of the solvent

to the needle 100 ml / min

to the column 690 ml / min

Temperature of the solvent

to the needle 40 ⁰ C

to the column 101 ⁰ C

from the column 74 ⁰ C

in the distillation vessel IH ⁰ C

Black microspheres with an average size of 350 microns were obtained. the Microspheres were immersed in concentrated ammonia solution for about 15 minutes, electrolyte free »Ο washed and dried.

Claims (6)

Patent claims: 1. Process for the production of compact metal oxide or metal carbide microspheres by Dropping a uranium dioxide, uranium trioxide, thorium dioxide, plutonium dioxide, plutonium trioxide, Zirconium oxide, beryllium oxide, yttrium oxide aquasols or a mixture thereof, during manufacture of metal carbides with up to 5 moles of colloidal carbon per mole of metal, in a dehydrating Solvent, isolation of the dehydrated microspheres from the dehydrating solvent and optionally sintering, thereby characterized in that the Aquasol is mixed with an ammonia-releasing agent and the mixture in a dehydrating Solvent, the temperature of which for a substantial decomposition of the ammonia-releasing Means is enough. 2. The method according to claim 1, characterized in that one is used as the dehydrating solvent Butanol, hexanol, ethylhexanol or ethylbutanol are used. 3. The method according to claim 1 and 2, characterized in that the microspheres up to a water content of less than 50 weight percent dries before they are removed from the dehydrating Removes solvent. 4. The method according to claim 1 to 3, characterized in that one of dissolved metal salts largely free Aquasol and the ammonia-releasing agent in one for setting the Aquasols to a pH of 1.0 to 0.1 pH units below the gelation pH of the Sols sufficient amount used. 5. The method according to claim 1 to 3, characterized in that an Aquasol is used which contains one or more dissolved salts of one or more of the metal cations U ⁺⁴ , (UO ₂ ) + ² , Th ⁺⁴ , Pu + ⁴ , (PuO ₂ ) + ² , (ZrO) + ² and Y + ³ in amounts up to saturation concentration. 6. The method according to claim 1 to 5, characterized in that the Aquasol with the ammonia-releasing agent mixed in an amount that is when the sol is introduced into the dehydrating Solvent to form a metal oxide gel from the metal compounds in the sol droplets sufficient.