JPS5950605B2 - How to treat uranium solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for extracting uranium from dilute uranium solutions containing acids or alkalis, such as extracts from uranium ores with acids or alkalis, or eluates of uranium from adsorbents in adsorption methods. The present invention relates to a processing method for concentrating uranium from a uranium-concentrating solution and recovering acid or alkali.

In recent years, due to the depletion of low-grade fuels such as oil and coal, nuclear power has been occupying a major position as an alternative energy source, and securing uranium, the raw material for nuclear power, has become an important issue.

This uranium is usually produced as uranium ores such as uranite and bitumenite, and is recovered from these ores by extraction methods.

Furthermore, uranium exists in seawater at a concentration of about 3 ppb as uranyl carbonate, and attempts have been made to recover this uranium by adsorption methods and the like.

When recovering uranium from natural resources in this way, it is necessary to concentrate dilute uranium solutions containing acids and alkalis, such as extracts from ores and eluates from adsorbents.

Until now, known methods for concentrating uranium from dilute uranium solutions include ion exchange, ion flotation, and solvent extraction.

However, the ion flotation method requires a long processing time and
It is unsuitable as an industrial method because it has drawbacks such as low recovery efficiency of coexisting acids and alkalis, and the solvent extraction method uses a large amount of solvent and must be carried out in special equipment. , it is not practical in that it inevitably increases the cost.

The present inventors have conducted various studies to develop a method for efficiently concentrating uranium and recovering acids and alkalis using simple operations from a dilute uranium solution. It was discovered that the objective could be achieved by filtering under pressure, and based on this knowledge, the present invention was accomplished.

That is, the present invention provides a method for processing a uranium solution, which comprises filtering a dilute uranium solution containing an acid or alkali through a polymer electrolyte membrane under pressure and separating it into an acid or alkali solution and a concentrated uranium solution. It provides:

The polymer electrolyte used as a filtration membrane in the method of the present invention is a polymer compound having a dissociative group such as a carboxylic acid residue, a sulfonic acid residue, a phenolic hydroxyl group, or an ammonium residue in its molecule.

In addition, an ultrafiltration membrane such as an acetylcellulose membrane or a polycarbonate membrane to which a polymer electrolyte or a charged dye is bonded can also be used.

Although not necessarily necessary, if the substance coexisting in the dilute uranium solution is alkali, one with an acid-type dissociative group, and if the coexisting substance is an acid, one with an ammonium-type dissociative group. It is advantageous to use, respectively.

The dilute uranium solution to be treated by the method of the present invention includes a dilute uranium solution containing an acid or alkali obtained by leaching uranium ore with an acid or alkali by an extraction method, and a dilute uranium solution containing various acids or alkalis obtained by leaching uranium ore in seawater by an adsorption method. After capturing with a capturing agent, there is an eluent obtained when the captured substance is eluted with an acid or an alkali.

In addition to uranium at a concentration of 1 to 20 mg/l, these dilute uranium solutions contain alkalis such as sodium carbonate, ammonium carbonate, sodium hydrogen carbonate, sodium phosphate, and disodium hydrogen phosphate, or acids such as hydrochloric acid and sulfuric acid. Contained at a concentration of 1 molar.

Treatment according to the method of the invention is carried out by passing a dilute uranium solution through a polymer electrolyte membrane under pressure.

The pressure used at this time is within a range of 10 kg/cm2 or less.

Through this treatment, acids or alkalis are concentrated in the permeated liquid, and uranium is concentrated in the residual liquid.

Through a single treatment according to the present invention, uranium is concentrated 20 times, and more than 90% of acids and alkalis are recovered.

In order to suitably carry out the method of the present invention, a plate-shaped polymer electrolyte membrane is placed inside a glass tube, and a dilute uranium solution is pressurized from the top to the bottom or from the bottom to the top.

At this time, the pressure shall be 10 kg/cm' or less, and the temperature shall be 5 to 50°C.

In addition, the membrane surface is stirred to eliminate concentration polarization.

After several hours of pressure filtration, an acid or alkali solution is recovered from the permeate, and a highly concentrated uranium solution is recovered from the concentrate.The acid or alkali solution can be reused as it is as a desorption solution or processing solution.

According to the present invention, the concentration of uranium in a dilute solution and the recovery of acids and alkalis can be performed simply and efficiently, and therefore it is suitable as an industrial method.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Using a commercially available polymer electrolyte membrane (composite membrane of sodium polystyrene sulfonate and polyvinylbenzyltrimethylammonium chloride, membrane thickness 100 μm, molecular weight cut off 500), uranium enrichment was 100 μg/l, hydrogen carbonate 1-'J 200ml of dilute aqueous uranium solution with a concentration of 0.5mol/1
was concentrated 10 times by pressure filtration at a pressure of 4 kg/cm2 and a permeation rate of 60 m1/hr.

In this way, the uranium concentration was concentrated to 970 μg/l, and 90% of sodium hydrogen carbonate was recovered.

Example 2 200 ml of an eluent (uranium concentration 2 mg/l) obtained by eluting an adsorbent treated in seawater for 10 days with a 0.5 M sodium bicarbonate aqueous solution was transferred to a commercially available polymer electrolyte membrane (molecular weight cut off). 500) using a pressure of 6 kg/cm2
The mixture was filtered under pressure and concentrated 10 times.

In this way, the uranium concentration was concentrated to 19 mg/1, and 85% of sodium bicarbonate was recovered.

Example 3 Polycarbonate ultrafiltration membrane (flat plate, 47 mmφ,
Using a polymer electrolyte membrane with polystyrene sulfonic acid pressed onto the pore size (0.015μ), a dilute uranium aqueous solution (
Uranium concentration 2.5mg/1), pressure 6kg/cm
It was filtered under pressure using □ and concentrated 10 times.

In this way, the uranium concentration was concentrated to 20 mg/l, and 90% of the hydrochloric acid was recovered.

Example 4 A dilute uranium solution (uranium concentration 2 mg/1) eluted with 0', OIN hydrochloric acid was filtered at a pressure of 6 mg/1 using an acetylcellulose type ultrafiltration membrane with poly-L-lysine crimped onto it.
It was filtered under pressure at kg/cm2 and concentrated 10 times.

The uranium concentration was concentrated to 15 mg/1, and 90% of hydrochloric acid was recovered.

Claims (1)

[Claims] 1. A method for processing a uranium solution, which comprises filtering a desired uranium solution containing an acid or alkali under pressure through a polymer electrolyte membrane and separating it into an acid or alkali solution, a uranium solution, and a uranium concentrate.