JPS5939163B2 - Composite magnetic adsorbent for uranium - Google Patents

Description

Detailed Description of the Invention The present invention uses a uranium adsorbent having uranium adsorption ability selected from titanic acid, magnesium hydroxide, and manganese dioxide, using ferromagnetic fine particles with an average particle size of approximately 0.01 to 5μ as cores. , relates to a composite magnetic adsorbent for uranium, characterized in that it is deposited directly on the surface of the ferromagnetic fine particles.

There are already frequent warnings of energy shortages in the near future.

For this reason, various energy sources are being researched and developed, and the most promising means for the time being seems to be the use of nuclear power.

However, regarding uranium, which is the base material for nuclear power generation, Japan's reserves of the resource are extremely small, and currently we have no choice but to mostly rely on imports from overseas.

On the other hand, there is a huge amount of uranium dissolved in canned water, and collecting and separating it is of great significance for Japan, which has extremely limited uranium resources.

Traditionally, adsorption methods have been considered effective for extracting uranium from seawater, and inorganic materials include metal oxides such as titanic acid and manganese dioxide, and hydrated metals such as aluminum hydroxide and magnesium hydroxide. Oxides, metal sulfides such as galena, activated carbon, or composites of activated carbon and metal oxides are known.As for organic materials, chelate-forming resins such as ion exchange resins and resorcinarsonic acid-formalin resins are known. ing.

In particular, inorganic adsorbents such as titanic acid, magnesium hydroxide, and manganese dioxide are considered to be excellent adsorbents.

When using an inorganic adsorbent to adsorb uranium, the general operations currently underway are as follows.

First, an aqueous solution containing one or several kinds of adsorbent raw material metal salts is prepared, and then, for example, by hydrolysis, a precipitate is deposited, and this precipitate is washed, filtered, and dried.

If necessary, perform mineral acid treatment during this time. The obtained fine powder adsorbent is suitably processed into granules, plates, or fibers, and then put into seawater.

After being in contact with seawater for several hours or days, the adsorbent is separated from the seawater.

Adsorbed uranium. The adsorbent is also treated with normal hydrochloric acid or immersed in an ammonia-ammonium carbonate aqueous solution to desorb uranium.

Reuse the adsorbent. Considering the above treatment method, extremely dilute uranium in seawater (0.00/11 seawater)
In order to efficiently adsorb 331n9) onto an adsorbent, it is expected that it is best to use an adsorbent with as large a surface area as possible, that is, to use as fine an adsorbent as possible to increase the contact area with seawater.

However, even if the ultrafine adsorbent dispersed in seawater adsorbs uranium, subsequent separation and collection operations from the seawater must rely on sedimentation or filtration; Therefore, it has a serious drawback that its separation and collection is extremely difficult.

As a result of intensive research into a method for easily separating and collecting uranium adsorbents from seawater or solutions containing uranium, the present inventors discovered that titanium By using a uranium composite magnetic adsorbent obtained by directly depositing a uranium adsorbent having uranium adsorption ability selected from magnesium hydroxide, manganese dioxide, and manganese dioxide on the surface of the ferromagnetic particles, the objective can be well achieved. The present invention was completed based on the knowledge that this can be done.

That is, according to the present invention, the uranium adsorbent is adsorbed onto the magnetic fine particles and becomes integrated, producing the same result as adding magnetism to the uranium adsorbent. This has the extremely remarkable effect of not only being able to easily separate and collect the adsorbed uranium, but also allowing easy recovery treatment after separating the adsorbed uranium.

Next, the present invention will be specifically explained.

The magnetic fine particles used in the present invention are magnetite, γ-
It is a ferromagnetic ferrite made of Fe8.03 and various other ferromagnetic ferrites, such as Mg, Ni, Mn, Co, Zn, etc., and its average particle size is about 0.
01 to 5μ is appropriate.

That is, if the average particle size is too small, the magnetism becomes weak and magnetic separation becomes difficult, and if the average particle size is too large, the contact area becomes small, which is inappropriate.

The magnetic fine particles are dispersed and suspended in distilled water, and in order to advantageously isolate the particles, it is effective to disperse them by irradiating them with ultrasonic waves.

Next, an aqueous solution containing one or more kinds of metal salts as adsorbent raw materials prepared separately in advance, such as titanium sulfate or titanium tetrachloride for Ti, magnesium carbonate for Mg, and manganese sulfate for M and n, is added to the above solution. Pour into the magnetic fine particle suspension and stir to mix.

At this time, it is appropriate to add the raw metal salt to the magnetic fine particles at a mixing weight ratio of about 0.5 to 5 in terms of the adsorbent raw metal.

That is, if the mixing ratio is too small, the adsorbent's ability to adsorb uranium becomes weak, and if it is too large, there is a limit to the amount that can be deposited on the magnetic particles, which is uneconomical.

Next, hydrolysis by pH adjustment and other usual precipitation operations are performed.

Precipitate formation is promoted on the surface of dispersed magnetic fine particles,
A precipitate is deposited.

In this way, the magnetic fine particles with the uranium adsorbent deposited on their surfaces are separated, washed, and dried using a suitable magnetic separator.

The composite magnetic adsorbent for uranium thus obtained is poured into seawater and dispersed, brought into contact with seawater to adsorb uranium, and then magnetically collected using an appropriate magnetic separation device.
Separates from seawater.

The adsorbent adsorbing uranium desorbs uranium using a conventional method.

The adsorbent that has desorbed uranium can be reused as is or after being activated.

Next, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 10μ of magnetite fine particles with an average particle size of 0.5μ
Add to ml of distilled water and irradiate with -28KC ultrasonic waves for about 10 minutes to fully disperse.

Add this to Ti20■/100ml! Add titanium sulfate and boil gently for about 30 minutes.

After cooling, the supernatant liquid is removed to obtain a slurry of magnequitotic acid composite fine powder.

This fine powder naturally exhibits ferromagnetism.

This stuff is seawater (uranium concentration 0.0033η/13)
57 and left to stand for 5 hours while stirring gently to adsorb uranium.

Next, this is passed through a magnetic separation device mainly using electromagnets to collect only the composite adsorbent, and then fresh seawater is added and left for 5 hours for magnetic separation.

This operation was repeated to bring 301 pieces of seawater into contact.

Seawater temperature was maintained at 30°C.

After the contact with seawater was completed, the composite adsorbent containing magnetically separated uranium was immersed in an ammonium carbonate-ammonia water mixture solution heated to 90°C and held for 1 hour while shaking to desorb uranium. .

The uranium concentration in the desorption solution was determined using a solid-state fluorescence method, and as a result, 70 μg of uranium was determined.

This corresponds to a capture rate of about 70% for uranium. Example 2 The same operation as in Example 1 was performed except that magnesium carbonate was used as the raw material metal salt, and a magnetite-magnesium hydroxide composite fine powder was obtained. As a result, 65 μg of uranium was present.

(Capture rate: 65%) Example 3 The same operation as in Example 1 was performed except that magnesium ferrite with an average particle size of 1 μm was used instead of magnetite and manganese sulfate was used as the raw metal salt. A ferrite-manganese dioxide composite fine powder was obtained, and the uranium adsorption operation was performed in the same manner as in Example 1. As a result of quantitative determination,
60 μg of uranium was present.

Claims (1)

[Scope of Claims] 1. Using ferromagnetic fine particles with an average particle size of about 0.01 to 5μ as cores, a uranium adsorbent having a uranium adsorption capacity selected from titanic acid, magnesium hydroxide, and manganese dioxide is applied to the ferromagnetic fine particles. A composite magnetic adsorbent for uranium that is deposited directly on the surface. 6