JPS5939374B2 - How to recover uranium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering uranium from a sulfuric acid acidic low concentration uranium solution containing organic matter.

Uranium is a useful substance as nuclear fuel, but since it is a radioactive substance, it is necessary to reduce the amount of uranium in the water discharged from smelters and factories to virtually zero.

In particular, when recovering uranium from uranium ore, one method is to leach the uranium ore with a large amount of sulfuric acid, extract uranium from the leachate with an extractant containing amine as a main component, and discharge the extraction residue as washing water after neutralization. It is adopted as one process.

However, since a small amount of uranium still remains in the residual liquid extracted with this amine, processing of the sludge after neutralization has become a problem.

In order to solve this problem, it is necessary to substantially remove uranium from the amine extraction residue (hereinafter referred to as sulfuric acid acidic low concentration uranium solution containing organic matter).

A simple method for removing uranium from these solutions is to bring it into contact with a uranium adsorbent.

The adsorbent for this purpose must satisfy the following requirements.

(1) Since the raw water is a sulfuric acid acidic solution, it can adsorb uranium in the sulfuric acid acidic aqueous solution. (2) Since the uranium concentration is very low, it has a strong absorption ability. (3) Many substances other than uranium can be absorbed. (4) Because the raw water is the residual liquid from amine extraction, the eluted uranium combines with amines to form salts or complexes. (5) It has the ability to adsorb uranium by bonding uranium and amine or breaking the bond; (5) It has strong resistance to organic contamination because several types of organic substances other than amines are mixed in the raw water; (6) Uranium adsorbed on the adsorbent can be easily desorbed and regenerated; and (7) the desorbent is easily available and inexpensive.

Further, the sulfuric acid acidic low concentration uranium solution will be explained in detail as follows.

Organic substances that coexist in sulfuric acid acidic low concentration uranium solution include:
Generally, it often contains amines, alcohols, and hydrocarbons at the same time.

That is, 3 having 7 to 15 carbon atoms such as trioctylamine.
Several hundred pp of amines, aliphatic alcohols with 6 to 12 carbon atoms such as 2-ethylhexylene alcohol, and hydrocarbons such as kerosene are added to a low concentration uranium solution with acidic sulfuric acid.
The content ranges from m to tens of thousands of ppm.

In particular, since most of the amines exist in combination with uranium, uranium cannot be adsorbed and removed using commercially available uranium adsorbents such as ion exchange resins for uranium, activated carbon, and oil adsorbents such as Kapok. is extremely difficult.

In the present invention, the sulfuric acid acidic low concentration uranium solution has a pH of 0.
5 to 3.5 and the uranium concentration is 0.1 to 30 pp
Refers to those containing m.

Furthermore, this solution contains other metals such as iron and manganese in addition to uranium, and it is necessary to selectively adsorb and remove only uranium from among these metals.

As a result of intensive study on these points, the present inventors found that
Polymer materials that have a pyridine skeleton structure in the main chain or side chain have an extremely excellent effect on uranium adsorption, and work effectively even under adverse conditions in the presence of organic substances such as those mentioned above, allowing for adsorption and desorption. The present inventors have discovered that the present invention is an excellent uranium adsorbent that can withstand repeated use.

In the present invention, a sulfuric acid acidic low concentration uranium solution in which organic substances such as amines coexist is brought into contact with a polymeric material having a pyridine skeleton structure in its main chain or side chain, and then the polymeric material is brought into contact with a uranium desorbing agent. This invention relates to a method for selectively and almost completely collecting and recovering uranium from a low concentration uranium solution acidified with sulfuric acid without being affected by organic matter.

The polymer material having a pyridine skeleton structure in the main chain or side chain in the present invention can be obtained by polymerizing a monomer containing a pyridine skeleton structure or by introducing a compound having a pyridine skeleton structure into the main chain or side chain of an appropriate polymer. obtained by

Vinylpyridines are conveniently used as monomers for this purpose.

Examples of vinylpyridines include 2-vinylpyridine,
Examples include 3-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine, 2-methyl-6-vinylpyridine, and 5-ethyl-2-vinylpyridine.

It can be obtained by copolymerizing these monomers alone or with other monomers.

Other monomers include styrene, aromatic vinyl compounds such as vinyltoluene, and unsaturated nitriles such as acrylic esters and methacrylic esters.

Other methods for introducing a pyridine skeleton structure into a polymer include a method in which a polymer having a hydroxyl group or a carboxylic acid group is subjected to an esterification reaction with pyridinecarboxylic acids or hydroxypyridines;
Examples include, but are not limited to, a method of reacting a polymer having a group with an aminopyridine or a pyridine carboxylic acid to obtain a polymer having a pyridine skeleton structure with an acid amide bond.

In the present invention, the polymer material having a pyridine skeleton structure in its main chain or side chain preferably has a three-dimensional structure from the viewpoint of strength.

To obtain a three-dimensional structure, it is generally necessary to add a crosslinking agent.

It is convenient to use polyvinyl monomers as crosslinking agents.

Examples of polyvinyl monomers include aromatic polyvinyl compounds such as hashivinylbenzene, divinyltoluene, divinylnaphthalene, trivinylbenzene, and diacrylic phthalate; aliphatic polyvinyl compounds such as ethylene glycol diacrylate and ethylene glycol dimethacrylate; divinylpyridine; Examples include nitrogen-containing polyvinyl compounds such as trivinylpyridine, divinylquinoline, and divinylisoxoline.

Another method for providing a three-dimensional structure is the method of quaternization crosslinking.

As the quaternized crosslinking agent, 1,2-dichloroethane, ■, 2
- Jibromueson, ■.

In the case of 2-chlorobutane, α,ω-alkyl dihalides can be used.

Among these crosslinking agents, divinylbenzene is generally easily available and convenient.

These crosslinking agents can be used in a ratio of 1 to 60 parts to the total monomers.

The polymer material in the present invention can have either a porous structure or a gel type structure, but a porous structure is preferable.

Moreover, this polymeric material can also be used together with a suitable carrier as required.

For example, it can be molded into an appropriate shape together with other materials such as inorganic materials such as activated carbon, silica gel, alumina, and graphite, or organic polymers such as polyvinyl chloride and polyvinylidene chloride.

Although the polymer material of the present invention can be used as it is,
It is preferably used in the form of pyridine sulfate by soaking it in an aqueous sulfuric acid solution.

By adopting the present invention, a polymeric material having a pyridine skeleton structure in the main chain or side chain adsorbs uranium that is not bonded to an amine, and also adsorbs uranium that is in the form of a complex or salt with an amine. can do.

Furthermore, the uranium collected in the polymeric material of the present invention can be easily desorbed from the polymeric material by contacting it with a sulfuric acid solution using a sulfuric acid solution as a desorbing agent, and the polymeric material can be reused. can.

A sulfuric acid solution as a desorbent having a concentration of 0.5 to 10 normal can be used.

In the present invention, the method of bringing the sulfuric acid acidic low concentration uranium solution into contact with the polymeric material can be any of the known solid-liquid contact methods, such as a batch stirring method, a fixed bed ion exchange method, and a moving bed ion exchange method. Examples include methods.

By employing the present invention, uranium can be selectively adsorbed from a sulfuric acid acidic low concentration uranium solution containing organic substances such as amines.

Furthermore, it is possible to remove uranium bonded to amines, and the polymer material of the present invention can be easily reused by desorbing uranium, and the desorbed uranium can also be removed. can be used as a resource.

Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples.

Example 1 4-vinylpyridine 41 and industrial divinylbenzene 10
1 g of benzoyl peroxide was added to the solution, and the mixture was reacted at 80° C. for 5 hours.

The obtained polymer was washed with methanol, crushed into pieces of about 20 to 50 meshes in size, and then thoroughly washed with an aqueous N-sulfuric acid solution.

This poly? -50771/ into a 3,000rn/ beaker and sulfuric acid acidic low concentration uranium solution shown in Table-1 2.
000m/ was added and stirred for 24 hours, the uranium concentration in the acidic low concentration uranium solution was 0.000m/. O decreased to 5ppm.

Comparative Example 1 In the same manner as in Example 1, commercially available ion exchange resins Amberlite IRA-400 (manufactured by Rohm & Barth), DOWEX 5BR-P (manufactured by Dow Chemical Company), and Diaion 5A-11A (manufactured by Mitsubishi Made by Chemicals (Porous Resin Amberly) XAD-4 (manufactured by Rohm & Bath Co.)
The same sulfuric acid acidic low concentration uranium solution used in Example 1 was treated using a uranium adsorbent such as , activated carbon and kapok (oil adsorbing vegetable fiber).

The results are shown in Table 2A.

In addition, a sulfuric acid acidic low concentration uranium solution containing no organic matter was treated using the polymer obtained in Example 1, the above-mentioned commercially available ion exchange resin, and porous resin, and the results were compared with the results in the coexistence of organic matter. Shown in 2B.

A sulfuric acid acidic low concentration uranium solution containing no organic matter is
Uranium oxide was dissolved in a normal aqueous solution of sulfuric acid (pH 1.1) to give a uranium concentration of 0.31 ppm.

As can be seen from Table 2B, commercially available ion exchange resins and porous resins significantly reduce their uranium adsorption ability in the coexistence of organic matter, whereas the adsorbent used in the present invention has excellent uranium adsorption ability even in the coexistence of organic matter. Adsorption ability can be maintained.

Example 2 A mixture of 130 g of 2-vinylpyridine, 90 g of industrial grade divinylbenzene, 50 g of isooctane and 3.3 g of benzoyl peroxide was mixed with 510 g of water.

It was dispersed in a mixture of 100 g of sodium formate, 2 g of gelatin and 0.5 g of polyvinyl alcohol.

It took one hour to raise the temperature to 800C, and the reaction was carried out at this hot water temperature for 7 hours.

After cooling, the obtained polymer was washed with methanol by Soxhlet extraction to obtain a white opaque resin (porous resin) 5
50m/ was obtained.

After the resin was washed with 2N sulfuric acid, a glass tube for chromatography was filled with Loom/, and a sulfuric acid acidic low concentration uranium solution shown in Table 3 was passed from the top at a rate of 10,100 O/Hr.

Analysis of the uranium concentration in the treated solution after 25 hours of flowing water revealed that it was 0.02 ppm. After thoroughly washing the resin with water, 1300 ml of 4N sulfuric acid was heated to 50°C and the flow rate was 50 ml/hr. It was eluted with

The results are shown in Table 4. Comparative Example 2 In Example 2, the resin was commercially available quaternary amine type Amberlite IRA-400 (manufactured by Rohm and Haas).
A low concentration sulfuric acid solution was passed through the tube in exactly the same manner except for the following steps.

The uranium concentration in the treatment solution after 25 hours of passing was 0.15 p.
It was pm.

Example 3 After washing 200rILl of the resin obtained in Example 1 with 2N sulfuric acid, 100m of the resin was washed with a diameter of 15mm and a height of 1000m.
A sulfuric acid acidic low concentration uranium solution 401 shown in Table 5 was passed through the column at a flow rate of 10,100 O/Hr.

The amount of uranium adsorbed on this resin was 0.0392 g.

After thoroughly washing this resin with water in step 11, the column was heated to 50°C.
moisturize, heat 4N-sulfuric acid to 50°C, and increase the flow rate to 5.
When eluted at 0 m1/Hr, the amount of uranium eluted was 0.
It was 0387g.

Thereafter, the same operation was repeated 50 cycles.

Claims (1)

[Claims] 1. Contacting a sulfuric acid acidic low concentration uranium solution in which organic matter coexists with a polymeric material having a pyridine skeleton structure in its main chain or side chain, and then contacting the polymeric material with a uranium desorbent. Features: A method for collecting and recovering uranium. 2. The method according to claim 1, wherein the polymeric material having a pyridine skeleton structure in its main chain or side chain is a copolymer of vinylpyridines and divinylbenzenes. 3. The method according to claim 1, wherein the coexisting organic substance is one or a mixture of two or more of amines, alcohols, and hydrocarbons. 4 A patent in which the sulfuric acid acidic low concentration uranium solution in which organic matter coexists is the raffinate solution obtained by extracting the liquid obtained by leaching uranium-containing ore with sulfuric acid using an amine extractant containing tertiary amine as the main component. The method according to claim 1. 5. The method according to claim 1, wherein the uranium desorbent is an aqueous sulfuric acid solution.