JP7701334B2 - How to dispose of silicon oil - Google Patents

Description

The present invention relates to a method for treating silicone oil.

In the controlled area of a nuclear power plant, facilities and equipment that use silicon oil are installed, and silicon oil is discharged periodically. Incineration, which can reduce the volume of waste, is a common method of disposing of waste oil, so it is conceivable to use a similar incineration method for silicon oil as well. For example, Patent Document 1 discloses a processing method in which the gas generated by incinerating silicon oil is filtered through a ceramic filter, and the incineration ash of the silicon oil is collected from the ceramic filter and disposed of as pellet-shaped waste.

JP 2012-26818 A

In the treatment method of Patent Document 1, a large amount of silicon dioxide (SiO ₂ ) fine particles are generated by incinerating the silicon oil, so frequent replacement of the ceramic filter is necessary. Ceramic filters are expensive, and since fine particles derived from the silicon oil discharged from the controlled area of the nuclear power plant are adsorbed, the waste must be treated as radioactive waste, so frequent replacement is problematic in terms of cost. Due to this background, the silicon oil is actually stored in liquid form at the site as before. However, even if silicon oil is stored in liquid form, it cannot solve the problem that a new dedicated storage facility and notification to related organizations are required as the storage amount increases.

The present invention was made based on this background, and aims to provide a method for disposing of silicone oil that can reduce the effort and cost required for disposing of silicone oil.

In order to achieve the above object, the method for treating silicone oil according to the present invention comprises the steps of:
A step of pouring granular material formed of a non-flammable porous material and silicone oil into a container;
an adsorption process in which an operator, wearing gloves, stirs the granular material and the silicon oil in the container while touching the granular material and the silicon oil with his/her hand, thereby adsorbing the silicon oil onto the granular material to such an extent that the silicon oil does not adhere to other objects even if the granular material comes into contact with the other objects;
Includes.

The present invention provides a method for disposing of silicone oil that can reduce the effort and cost required for disposing of silicone oil.

1A and 1B are diagrams illustrating the processing of silicon oil in a container according to an embodiment of the present invention. 1 is a flowchart showing the flow of a method for treating silicon oil according to an embodiment of the present invention. 4A and 4B are photographs showing the appearance of the granular material after adsorption of silicone oil in an example.

The method for treating silicon oil according to the embodiment of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or equivalent parts are given the same reference numerals.

The method for treating silicon oil according to the embodiment is a method for stably solidifying silicon oil by adsorbing the silicon oil to a large number of granular bodies formed of a non-flammable adsorbent that adsorbs silicon oil. Specifically, as shown in FIG. 1, silicon oil and a large number of granular bodies are placed in container 1, and the two are stirred in container 1 to adsorb the silicon oil to the granular bodies. This makes it possible to solidify the silicon oil to a degree that it does not fall under the category of designated flammable materials as defined by the Cabinet Order on the Regulation of Hazardous Materials.

Methods for solidifying silicone oil include solidifying the silicone oil using a coagulant, or soaking the silicone oil into an object that absorbs liquids, such as a rag or sponge. However, with either method, the silicone oil gradually seeps out to the surface over time, making it a designated combustible material as stipulated in the Cabinet Order on the Regulation of Hazardous Materials. On the other hand, with the silicone oil treatment method according to the embodiment, the silicone oil once adsorbed onto the granular material does not seep out to the surface of the granular material, and the heat of combustion of the non-flammable granular material that has adsorbed the silicone oil does not make it a designated combustible material as stipulated in the Cabinet Order on the Regulation of Hazardous Materials.

The adsorbent according to the embodiment is formed of a porous material having a large number of micropores. The porous material is, for example, a porous ceramic material formed of a ceramic material. The average diameter of the micropores is set to a degree that allows the silicone oil to be trapped by surface tension. Specifically, the average diameter of the micropores is, for example, 10 μm or less, preferably 1 μm or less, and more preferably 0.3 μm or less.

For example, diatomaceous earth, clay, zeolite, zirconia, and alumina can be used as the raw material for the adsorbent according to the embodiment, but it is preferable to use diatomaceous earth. Diatomaceous earth is a deposit containing fossilized diatom shells, and contains silicon dioxide as a main component. Various additives, for example, sodium carbonate, may be added to the raw material for the adsorbent. The granular material according to the embodiment may be of any shape, but is preferably spherical or cylindrical, for example. As an example, the granular material according to the embodiment is cylindrical, formed within a range of 0.5 mm to 2 mm in diameter and 1 to 3 mm in length.

The granular body according to the embodiment is manufactured, for example, by crushing the raw material diatomaceous earth into a powder using a crusher, adding water to the crushed diatomaceous earth and kneading it, molding the kneaded product, and then firing it at a high temperature. By firing the molded product at a high temperature, impurities contained inside can be removed. In the kneading process, additives may be added as necessary. In the molding process, for example, the product may be molded into a cylindrical shape using an extrusion molding machine.

The granular material according to the embodiment is able to trap and stably hold the silicone oil inside the micropores due to the action of surface tension, so it remains in a dry state even after absorbing the silicone oil. A dry state means that the silicone oil does not seep out from the surface after absorbing the silicone oil, and even if it comes into contact with another object, the silicone oil does not adhere to the other object. In the dry state, oxygen cannot come into contact with the silicone oil trapped in the micropores, so sufficient flame retardancy can be obtained despite the silicone oil being absorbed.

Next, the flow of the method for treating silicon oil according to the embodiment will be described with reference to FIG.
First, the silicon oil to be disposed of, which is contained in the can 2, is poured into the container 1 (step S1). At this time, it is preferable to confirm that the temperature of the silicon oil is equal to or higher than the pour point. This is because, if the temperature of the silicon oil is lower than the pour point, the fluidity decreases, and the silicon oil may not be adsorbed by the granules in the process described below. If the temperature of the silicon oil is lower than the pour point, the silicon oil may be appropriately heated in the can 2 before being poured.

Next, a large number of granular materials are poured into the container 1 into which the silicone oil was poured in step S1 (step S2). The granular materials are packed in bags 3 and can be poured directly into the container 1.

Next, the silicone oil and a large number of granules are stirred in the container 1, and the silicone oil is absorbed by the granules (step S3). This stirring can be done manually, for example, by an operator wearing gloves. In this process, the silicone oil is repeatedly brought into contact with the entire surface of the granules, so that the silicone oil is absorbed quickly and reliably by the granules, and the completion of the absorption of the silicone oil is confirmed by touching the granules.

Next, the granules that have absorbed the silicon oil in the process of step S3 are collected from the container 1 (step S4). The granules that have absorbed the silicon oil may be returned to the bag 3 in which the granules were packed before absorption. The bag 3 containing the granules that have absorbed the silicon oil may be transported to, for example, a solid waste storage facility of a nuclear power plant and stored together with other solid waste.
The above is the flow of the silicone oil treatment method.

The method for treating silicon oil according to the embodiment has the following advantages over the storage of liquid silicon oil. First, to store liquid silicon oil, a dedicated storage facility different from the solid waste storage facility is required, but with the method for treating silicon oil according to the embodiment, granular material adsorbing silicon oil can be stored in an existing solid waste storage facility. Also, to store a certain amount of liquid silicon oil or more, a notification to the fire department is required, but with the method for treating silicon oil according to the embodiment, since the granular material adsorbing silicon oil does not fall under the designated combustible material specified by the Cabinet Order on the Regulation of Hazardous Materials, a notification to the fire department is not required even if a certain amount or more is stored. And the granular material adsorbing silicon oil can be disposed of as solid waste in the same manner as other solid waste.

As described above, the method for treating silicon oil according to the embodiment includes a process for adsorbing silicon oil to granules formed of a non-combustible porous material. Therefore, compared to other treatment methods such as incineration, the silicon oil can be solidified using a simple method, and can be stored in a solid waste storage facility like other solid waste. In addition, the granules formed of a non-combustible porous material can be obtained inexpensively. As a result, the effort and cost required for disposing of silicon oil discharged from within the controlled area of a nuclear power plant can be reduced compared to conventional methods.

The present invention is not limited to the above embodiment, and the following modifications are also possible.

(Modification)
In the above embodiment, the adsorbent is charged into the container 1 after the silicone oil is charged into the container 1, but the present invention is not limited to this. Conversely, the adsorbent may be charged into the container 1, and then the silicone oil may be charged into the container 1.

In the above embodiment, the adsorbent and silicon oil are added and stirred manually, but the present invention is not limited to this. The adsorbent and silicon oil may be added manually and stirred using an agitator. The agitator may, for example, be equipped with a stirring blade capable of stirring the target material by rotating, and may be held manually so that the stirring blade comes into contact with the adsorbent and silicon oil in the container 1.

In addition, a processing device that introduces and agitates the adsorbent and silicon oil may be used to process the adsorbent and silicon oil. The processing device may be configured, for example, to be installed above the container 1, introduce the adsorbent and silicon oil contained therein into the container 1 in response to a user's instruction, and then rotate the adsorbent and silicon oil introduced into the container 1 to agitate the target object with an agitator blade.

In the above embodiment, the diatomaceous earth is crushed, kneaded, molded, and fired as a manufacturing process for the granular material, but the present invention is not limited to this. For example, if the purity of the diatomaceous earth is high, the diatomaceous earth may be crushed into granules using a crusher, and the granular material may be dried to manufacture the granular material. The granular material may be dried, for example, by natural drying or high-temperature drying.

In the above embodiment, the solidification of the silicone oil discharged from within the controlled area of the nuclear power plant was carried out, but the present invention is not limited to this. The treatment method of the above embodiment may be applied to the treatment of silicone oil discharged from other locations, not limited to the controlled area of the nuclear power plant.

The above embodiments are examples, and the present invention is not limited to these, and various embodiments are possible without departing from the spirit of the invention described in the claims. The components described in the embodiments and variations can be freely combined. Furthermore, inventions equivalent to the inventions described in the claims are also included in the present invention.

The present invention will be specifically explained below with reference to examples. However, the present invention is not limited to these examples.

(Example)
In the example, liquid silicone oil stored at a power plant was disposed of. The silicone oil to be disposed of was used silicone oil that had been divided into 20 L cans and stored.

The specific procedure for the treatment is described below. First, the silicon oil stored in a 20 L can was poured into the work container, and then a total of 30 kg (60 L) of the adsorbent granules was poured into the work container. The capacity of the work container was 170 L. The adsorbent granules were a commercially available road surface oil treatment material manufactured by crushing diatomaceous earth into powder, forming it, and baking it at high heat. Next, the granules and silicon oil were manually stirred in the work container. As a result, the silicon oil was easily adsorbed into the granules by the worker simply by stirring it manually. The granules with the silicon oil adsorbed were in a smooth state as shown in Figure 3 (a), and no silicon oil was attached to the gloves of the worker after the work.

Next, the granules with the silicone oil adsorbed were returned to the bag in which they were originally stored, and the granules were observed for a long period of time to see if the silicone oil would seep out from the granules. As a result, as shown in Figure 3(b), the silicone oil did not seep out from the granules with the silicone oil adsorbed, and no silicone oil adhered to the bag.

Subsequently, test results proved that the granular material with silicon oil adsorbed on it was not a designated flammable material in terms of the heat of combustion, and we received the opinion from the fire department that the granular material with silicon oil adsorbed on it was not a designated flammable material as stipulated in the Cabinet Order on the Control of Hazardous Materials.

1 container 2 cans 3 bags

Claims (4)

A step of pouring granular material formed of a non-flammable porous material and silicone oil into a container ;
an adsorption process in which an operator, wearing gloves, stirs the granular material and the silicon oil in the container while touching the granular material and the silicon oil with his/her hand , thereby adsorbing the silicon oil onto the granular material to such an extent that the silicon oil does not adhere to other objects even if the granular material comes into contact with the other objects ;
A method for treating silicon oil comprising the steps of: The silicone oil was discharged from within the controlled area of a nuclear power plant.
The method for treating silicon oil according to claim 1. The granules are formed of a porous ceramic material.
The method for treating silicon oil according to claim 1 or 2. The granules include diatomaceous earth.
The method for treating silicon oil according to claim 3.

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