JP2000206290A - Treatment device for adsorbent for metal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to extract an adsorbent adsorbing metal elements from a container without scattering them. SOLUTION: A funnel 27 whose circumferential face is shaped like a truncated cone and which is made of wire gauge is placed on the downstream side inside a column 2 to be filled with an adsorbent 1. A lower opening 27b of the funnel 27 is connected to an outlet 26 of the column 2 and communicates with a recovery container 13 through an exhaust pipe 12 outside the column 2. An extraction valve 14 is fitted onto the exhaust pipe 12 to perform an opening and closing operation. A space 28 whose section partitioned by the column 2 and the funnel 27 is an approximate right triangle and which is shaped annularly is connected with an exhaust pipe 17. When metal elements are adsorbed, a radioactive liquid waste is separated from the adsorbent 1 in the space 28 through the wire gauge of the funnel 27 and is exhausted. When the adsorbent 1 is dried, hot air is also separated from it by the funnel 27. The adsorbent 1 that is dried and granulated is guided and exhausted from the inside of the column 2 by the funnel 27 and is housed in the recovery container 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for treating a metal element adsorbent for adsorbing a metal element such as uranium or chromium onto an adsorbent such as insoluble tannin and performing a recovery treatment.

[0002]

2. Description of the Related Art Conventionally, actinide elements such as uranium, thorium and transuranium elements, heavy metal elements including cadmium, lead, chromium, mercury and iron, or cobalt, cesium,
As an adsorbent of a metal element for adsorbing a metal element such as strontium, there is an adsorbent composed of a stabilized gel-like composition using condensed tannin as a raw material. JP-A-5-66291 proposes a production method and a method for adsorbing and separating a metal element. This adsorbent is prepared by dissolving condensed tannin powder in ammonia water and mixing with an aqueous aldehyde solution using, for example, a condensed tannin which is present in a large amount and does not contain persimmon astringent as disclosed in the above-mentioned publication. It is obtained by producing a composition and stabilizing the gel composition by aging or heating. The stabilized gel composition becomes a composition insoluble in any of water, acid and alkali.

[0003] The adsorbent thus obtained is
It not only excels in the adsorption performance of uranium, thorium, and uranium in seawater generated from the nuclear fuel production process, but also from the process of handling the transuranium elements, curium, americium, neptunium, plutonium, and further metal elements generated from the reprocessing process. It has excellent adsorption performance for various metal elements such as cadmium, lead, hexavalent chromium, mercury, iron, cobalt, cesium, and strontium. In addition, since the adsorbent having adsorbed the metal can be incinerated without generating toxic gas, the volume of the adsorbent can be greatly reduced by incineration, and the amount of solid waste generated can be reduced.
Further, depending on the metal element adsorbed, the solid substance becomes a metal oxide containing no impurities, and thus can be reused. Furthermore, since this adsorbent is a gel composition, its form is not easily collapsed, and the adsorbed metal element can be easily dissolved from the gel composition to recover and purify the metal.

By the way, in order to adsorb a metal element such as uranium or transuranium from a waste liquid containing uranium or transuranium discharged in a process of handling nuclear fuel, for example, mechanical means or the like is installed in a column which is a packed cylinder. Fill the adsorbent of the gel composition disintegrated to the desired size to the desired height, supply the radioactive waste liquid into the column in this state, and adsorb the metal element such as uranium or transuranium element to the adsorbent Let it. Adsorption is carried out until breakthrough of the adsorption capacity of the adsorbent is reached. The adsorbent on which the metal element has been adsorbed in this manner is in a state of being tightly packed in the column and cannot be easily extracted. The processing for drying and extracting the used adsorbent is performed by the steps shown in FIG. In FIG. 5, the upper lid 3 (or the lower bottom may be disassembled) of the column 2 filled with the adsorbent 1 on which the metal element has been adsorbed, and the adsorbent 1 is manually scraped out of the column 2 or sucked by a suction machine or the like. Then, it is stored and placed on the drying vat 4 (see FIG. 3A). Next, these drying vats 4 are housed in a box-shaped dryer 5 and heated to dry the adsorbent 1 (see FIG. 2B). Then, the dried adsorbent 1 is filled into the collection container 7 by the food box 6 (see FIG. 3C),
The volume of the waste is reduced by burning or the like, and a specific metal element is recovered as a metal oxide containing no impurities and reused.

[0005]

However, in such a method for removing the used adsorbent, the fluidity of the adsorbent 1 is extremely poor because water is contained between the particles of the adsorbent 1 in the column 2. Cannot be easily extracted from the column 2. Therefore, since the upper lid 3 or the lower bottom of the column 2 must be dismantled and the adsorbent 1 must be manually scraped out, the work becomes labor intensive and takes a long time. There is a risk of peripheral contamination due to scattering of objects. In addition, not only the column 2 but also many other devices such as a drying vat 4, a dryer 5, a food box 6, and the like are required, resulting in a disadvantage that the cost is increased. In view of such circumstances, an object of the present invention is to provide a processing device for a metal element adsorbent capable of easily taking out the adsorbent without fear of scattering.

[0006]

A metal element adsorbent treatment apparatus according to the present invention supplies a solution containing a metal element into a container containing an adsorbent for adsorbing the metal element, and supplies the solution containing the metal element to the container. The metal element is adsorbed on the adsorbent and dried, and the adsorbent is discharged in the treatment device for the metal element adsorbent. A guide part to pass through is arranged,
An opening / closing means for removing the adsorbent from the container is provided. The adsorbent in the container is filled and stored up to the guide portion, and a solution containing the metal element is flowed into the container to adsorb the metal element to the adsorbent and adsorb until the adsorbent reaches a breakthrough in the adsorption capacity. The solution after passing through the adsorbent and deprived of the metal element in the process or the solution before reaching the adsorbent passes through (permeates) the guide surface and is separated from the adsorbent or permeates into the adsorbent I do. Further, the used adsorbent having the metal element adsorbed thereon flows out along the surface of the guide portion and is taken out of the column and recovered by switching the open / close member after drying. The guide portion may be formed in a tapered shape, the upper opening may be in contact with the inner surface of the container, and the lower opening may be connected to the outlet of the container.

Further, a space separated by the container and the guide portion may be formed around the guide portion, and a discharge pipe or a supply pipe may be connected to this space. The solution separated from the adsorbent after passing through the surface of the guide portion is discharged from the space through the discharge pipe. Alternatively, the solution supplied to the space of the container passes through the adsorbent through the guide portion. Further, at least a part of the guide portion may be formed in a mesh shape or a hole may be formed in at least a part. The solution passing through the guide portion is circulated through a mesh or a hole in the surface of the guide portion, and the adsorbent is discharged along the guide portion without passing through the mesh or the hole.

[0008]

FIG. 1 is a block diagram showing an embodiment of the present invention.
3 to FIG. 3, the same parts as those in the above-described prior art will be described using the same reference numerals. FIG. 1 is a schematic configuration diagram of an apparatus for treating an adsorbent according to an embodiment of the present invention, and FIG.
FIG. 3 is a main part configuration diagram of a take-out mechanism including a column filled with a metal element, and FIG. 3 is a flowchart showing an adsorption drying process and a take-out process of an adsorbent. In the adsorbent treatment apparatus 10 shown in FIG. 1, a filling cylinder, for example, a column 2 is filled with the adsorbent 1 composed of the insoluble tannin composed of the gel composition using the above-mentioned condensed tannin as a raw material. A solution supplied from a waste liquid tank (not shown) via the supply pipe 11, for example, a radioactive waste liquid is supplied to the upper portion 2 a of the column 2.
And metal elements such as uranium and thorium contained in the radioactive waste liquid are adsorbed by the adsorbent 1.
Further, in this processing apparatus 10, as shown in FIGS.
The discharge pipe 12 is provided with a withdrawal valve 14 that can be switched between open and closed, as an opening and closing means. By opening the valve, the adsorbent 1 in the column 2 can be discharged into the collection container 13. ing.

An air heater 16 is connected to the upper part 2a of the column 2 via a pipe 15, and the heated air is supplied to the upper part 2a of the column 2 as hot air. The adsorbent 1 is located in the lower 2b area of the column 2.
A discharge pipe 17 for discharging the hot air or the radioactive waste liquid passing therethrough is connected to the discharge pipe 17, and the discharge pipe 17 is provided with exhaust temperature measuring means 18 for measuring the exhaust temperature of the internal hot air. Here, the temperature of the hot air supplied to the adsorbent 1 is adjusted so that the substance contained in the radioactive waste liquid or the like adhering to the adsorbent 1 or the column 2, for example, a nitric acid compound is not decomposed and generates heat or expands in volume. The temperature is set lower than the temperature at which such a substance is decomposed. For a radioactive waste liquid containing uranium or the like, the temperature is set to, for example, about 140 ° C., and the temperature is measured by the supply air temperature measuring means 19.

The exhaust gas temperature measuring means 18 and the supply air temperature measuring means 19 are connected to the air heater 16 via the control means 20, and when the adsorbent 1 in the column 2 is dried by hot air, the drying proceeds. In this state, the exhaust gas temperature is measured as a substantially constant temperature T0. However, when drying is completed, the exhaust gas temperature rises to a temperature T1 exceeding T0 and gradually rises. The heater 16 is turned off, and the supply of hot air is stopped. The temperature T0 is, for example, about 35 ° C. to 50 ° C., and the exhaust temperature T1 is, for example, about 80 ° C. A washing liquid such as water is supplied to the column 2 through the pipe 22.
The cleaning liquid supply means 23 supplied from a is connected.

In the adsorbent removal mechanism 25 including the column 2 and the extraction valve 14 shown in FIG. 2, a discharge port 2 communicating with the discharge pipe 12 is provided at the center of the lower part 2b of the column 2.
6, a funnel 27 having a substantially frustoconical peripheral surface shape is mounted as a guide portion below the substantially cylindrical column 2. The funnel 27 is formed of a metal mesh made of a suitable metal material, and an upper opening 27a having a maximum inner diameter of a truncated conical peripheral surface is in contact with the inner peripheral surface of the column 2 and a lower opening 27b having a minimum inner diameter is provided with an outlet 26. It is connected to. Therefore, the upper opening 27a has a diameter substantially the same as the inner diameter of the column 2, and the lower opening 27b has a diameter substantially the same as the inner diameter of the outlet 26. A space 28 is formed in the lower part 2b of the column 2 and is partitioned by the peripheral surface 2c and the peripheral surface of the funnel 26, and communicates with the discharge pipe 17.

An adsorbent processing apparatus 10 according to the present embodiment.
Is configured as described above. Next, a processing method for adsorption drying and removal of the adsorbent 1 will be described with reference to a flowchart shown in FIG. In order to adsorb and separate only the metal element such as uranium from the radioactive waste liquid containing the metal element such as uranium, the column 2 is filled with an adsorbent 1 composed of a pulverized gel-like composition, Column 2
By supplying a radioactive waste liquid into the inside (step 101), only the metal element can be adsorbed on the adsorbent 2 with a high adsorption rate. The waste liquid from which most of the metal elements have been adsorbed and removed flows out into the space 28 through the wire mesh which is the peripheral surface of the funnel 27 below the column 2. The gas is discharged from the space 28 to the outside of the column 2 via the discharge pipe 17 (step 1).
02). Since the adsorbent 1 has an extremely high adsorption capacity for metal elements such as uranium, measuring the residual ratio of the metal element in the radioactive waste liquid discharged from the column 2 allows the adsorbent 1 in the column 2 to reach a breakthrough point. You can confirm that it has been reached. When the adsorption capacity of the adsorbent 1 reaches the breakthrough, the supply of the radioactive waste liquid is stopped, and the adsorption step is completed. In this state, the metal element is adsorbed on the adsorbent 1 in the column 2 and is tightly packed in the column 2, so that the adsorbent 1 cannot be easily removed.

Next, for example, water is supplied from the cleaning liquid supply means 23 as a cleaning liquid into the column 2 and flows therethrough. Radioactive waste liquid remaining in the column 2 is extruded and passed through the funnel 27 to pass through the space 28 and the discharge pipe 17. It is discharged (step 103). At this time, since the metal element such as uranium is adsorbed by the adsorbent 1, it does not dissolve in the cleaning liquid such as water. Here, if the drying treatment is performed without passing water through the column 2, ammonium fluoride and other nitric acid salts in the remaining radioactive waste liquid are dried and precipitated, and the adsorbent is fixed, and the column 2 Emission from ash becomes difficult. The air heated by the air heater 16 has a temperature of about 14
The hot air of about 0 ° C. is supplied to the column 2 through the pipe 15 to dry the adsorbent 1 (Step 104). The hot air that has passed through the adsorbent 1 is discharged into the space 28 through the wire mesh of the funnel 27 and is discharged outside through the discharge pipe 17. When the adsorbent 1 is ventilated, heat is taken away as heat of vaporization of water contained in the adsorbent 1, so that the temperature of the hot air that has passed through the adsorbent 1 decreases and the hot air that has passed through the adsorbent 1 is exhausted at, for example, about 35 ° C to 50 ° C. It is discharged at the temperature T0. This exhaust gas temperature is detected by the exhaust gas temperature measuring means 18. As the drying of the adsorbent 1 proceeds, the volume of the adsorbent 1 decreases, and the height in the column 2 also gradually decreases from h1 in FIGS. 1 and 2, and at the end of drying, the volume is reduced to about the height h2 (for example, 1 / 5). During this time, the exhaust temperature of the hot air is maintained at a substantially constant temperature T0 because heat is continuously taken away.

When the drying of the adsorbent 1 is completed, the heat is not deprived when the hot air passes through the adsorbent 1, and the exhaust temperature becomes T0.
Gradually rises from. When the exhaust gas temperature measured by the exhaust gas temperature measuring means 18 rises from T0 to T1 (for example, 80 ° C.), the control means 20 stops driving the air heater 16 and the hot air supply ends and the drying step ends. I do. Adsorbent 1
When is dried, the adsorbent 1 shrinks and becomes a granule having excellent fluidity. In this state, if the extraction valve 14 is opened, the granular adsorbent 1 in the column 2 is guided by the funnel 27, flows out through the discharge port 26 and the discharge pipe 12, and is easily stored in the collection container 13. In this way, the volume of the adsorbent 1 is greatly reduced, and the adsorbent 1 can be easily discharged and collected from the column 2.
Thereafter, the adsorbent 1 can be decomposed by incineration to decompose the adsorbent 1 made of insoluble tannin, and a metal element such as uranium can be recovered as a metal oxide with high purity, thereby preventing generation of secondary waste.

As described above, according to the present embodiment, when the metal element is adsorbed, the radioactive waste liquid after the metal element is adsorbed is easily separated from the adsorbent 1 in the column 2 through the wire mesh of the funnel 27 and discharged. Hot air can be used for drying
Can be separated out in the column 2 through the wire mesh and exhausted to the outside. In addition, when the adsorbent 1 after drying is recovered, the granulated adsorbent 1 is guided to the outlet 26 by the funnel 27 through the outlet pipe 12. The radioactive waste liquid and hot air for drying can be easily separated and discharged from the adsorbent 1 and the adsorbent 1 can be easily taken out by the simple adsorbent 1 take-out mechanism 25. In addition, radioactive waste liquid and radioactive metal elements such as uranium can be taken out of the column 2 without scattering and without causing peripheral contamination.

FIG. 4 shows a modification of the adsorbent processing apparatus 10 according to the present embodiment.
0, the supply pipe 11 for supplying the radioactive waste liquid to the column 2 is connected near the lower portion 2b of the column 2 and the space 28
And a discharge pipe 17 for discharging the waste liquid that has passed through the adsorbent 1 to the outside of the column is connected near the upper portion 2a of the column 2. Therefore, when the metal element is adsorbed, the radioactive waste liquid is supplied into the column 2 and is discharged from the space 28 to the funnel 27.
, Penetrates the adsorbent, flows upward from below, and is discharged from the discharge pipe 17 in the upper portion 2a. In this case, the cleaning liquid of the cleaning liquid supply means 23 and the air heater 16
Similarly, the hot air heated by the above flows from the pipe 22 and the pipe 15 in the column 2 from downstream to upstream. Alternatively, it may flow from upstream to downstream as in the embodiment shown in FIG.

In the above-described embodiment, the funnel 27 formed of a wire mesh is used as the guide portion. However, the tapered peripheral surface of the funnel 27 is not limited to a mesh-like structure such as a wire mesh. Any material or configuration may be used as long as it is liquid-permeable and air-permeable, and may be, for example, a porous sintered metal peripheral surface or a peripheral surface formed with an appropriate number of small holes such as punch holes. Further, the wire mesh, the holes, and the like do not necessarily need to be formed on the entire peripheral surface of the funnel 27, and may be formed on a part thereof. In addition, the treatment apparatus 10 for the adsorbent 1 according to the present invention is not limited to waste such as the above-mentioned radioactive waste liquid containing uranium, but includes uranium and thorium generated from a nuclear fuel production process, and transuranium generated from a reprocessing process. The elements curium, americium, neptunium, plutonium,
Cadmium generated from the process of handling metal elements,
For drying and taking out the adsorbent 1 that adsorbs these metal elements from various solutions including wastewater containing various metal elements such as lead, hexavalent chromium, mercury, iron, cobalt, cesium and strontium, and seawater containing uranium Can be used.
The column 2 constitutes a container.

[0018]

As described above, the apparatus for treating a metal element adsorbent according to the present invention is provided with a guide section for accommodating the adsorbent in a container, guiding the outflow thereof, and passing the solution. An opening / closing means for removing the adsorbent from the container is provided, so that when the metal element is adsorbed, the solution after the metal element has been adsorbed can be easily separated from the adsorbent through the guide section and discharged, and the adsorbed substance after drying When collecting the adsorbent, the granulated adsorbent can be guided by the guide part and easily discharged to the outside, and can be easily collected and recovered.With a simple structure, the solution etc. can be easily separated and discharged from the adsorbent, and the adsorbent can be taken out. Easy to do. In addition, the adsorbent and the metal element can be taken out of the container without being scattered.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an adsorbent processing apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing an adsorbent removing mechanism of the processing apparatus shown in FIG.

FIG. 3 is a flowchart showing a process of treating the adsorbent in the adsorbent treating apparatus according to the embodiment.

FIG. 4 is a main part configuration diagram showing a modification of the adsorbent processing apparatus according to the embodiment.

FIG. 5 is a diagram showing a step of drying and taking out an adsorbent on which a metal element is adsorbed in a conventional method of treating an adsorbent, wherein (a) shows a step of transferring the adsorbent from a column to a drying vat; (b) is a diagram illustrating a process of drying the adsorbent, and (c) is a diagram illustrating a process of transferring the adsorbent to a collection container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adsorbent 2 Column 10 Adsorbent processing apparatus 12 Discharge pipe 14 Extraction valve 17 Discharge pipe 25 Adsorbent take-out mechanism 27 Funnel 28 Space

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Nobumura 622-1, Funashiishikawa, Tokai-mura, Naka-gun, Ibaraki Prefecture Inside Mitsubishi Nuclear Fuel Co., Ltd. (72) Inventor Tsugio Nakagawa 622, Funai-ishikawa, Tokai-mura, Naka-gun, Ibaraki Address 1 F term in Mitsubishi Nuclear Fuel Co., Ltd. (reference) 4G066 AB06A AB06B AB29A AB29B BA28 CA12 CA46 CA49 CA50 DA08

Claims (1)

[Claims] 1. A solution containing a metal element is supplied into a container containing an adsorbent for adsorbing a metal element, and the metal element in the solution is adsorbed by the adsorbent and dried. In the apparatus for treating a metal element adsorbent that is discharged, a guide portion that accommodates the adsorbent, guides the outflow thereof, and passes the solution is disposed in the container, and the adsorbent is removed from the container. An apparatus for treating a metal element adsorbent, comprising an opening / closing means for taking out the metal element.