Container disposal method

Abstract

To provide a method for safely and easily disposing of a container in which a water-prohibitive deleterious substance or a toxic substance is stored.SOLUTION: A method for disposing of a container containing a water-prohibitive deleterious substance or toxic substance, comprising the steps of: attaching a plug to a valve opening of the container, the plug being brought into an open state by a pressure lower than a pressure test pressure of the container; and putting the container with the plug attached into a heating furnace and heating the container.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for disposing of containers. [Background technology]

[0002] In containers containing water-resistant or pyrophoric substances that ignite and pose an explosion risk when exposed to air or water, even the smallest amount of air or water cannot be allowed to get mixed in. For example, Patent Document 1 discloses a method for handling pyrophoric substances that can safely handle pyrophoric substances by preventing air from leaking into piping from a valve, and a valve device used for this method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-232291 Summary of the Invention [Problem to be solved by the invention]

[0004] In particular, when disposing of containers (such as discarded cylinders) that have contained water-resistant, toxic or deleterious substances by incineration, it is necessary to open the sealed container before placing it in the incinerator to prevent explosions. However, there is a risk of toxic gas being generated when opening the container, making it an extremely difficult task.

[0005] On the other hand, there is a growing need for the disposal of containers that have contained water-resistant, deleterious or toxic substances, making it difficult for users to secure disposal sites. This has led to the risk of accidents occurring due to improper disposal or long-term storage, such as corrosion of the containers.

[0006] An object of one embodiment of the present invention is to provide a method for safely and easily disposing of a container that has contained a water-resistant deleterious or poisonous substance. [Means for solving the problem]

[0007] A first aspect of the present invention is A method for disposing of containers that have contained water-resistant deleterious or poisonous substances, comprising the steps of: an attachment step of an open plug that is attached to the valve opening of the container and that is in an open state when subjected to a pressure that is less than the pressure test pressure of the container; and a step of heating the container with the stopper attached in a heating furnace.

[0008] A second aspect of the present invention is In the method for waste disposal of containers according to the first aspect, the deleterious or toxic substance includes a superacid, which is an acid stronger than 100% sulfuric acid.

[0009] A third aspect of the present invention is In the method for disposing of a container according to the first aspect, the plug is a relief valve that opens when a pressure equal to or less than 0.5 times the pressure test pressure of the container is applied.

[0010] A fourth aspect of the present invention is In the method for waste disposal of a container according to the first aspect, the step of attaching the release plug is carried out in a sealed container under an inert gas atmosphere.

[0011] A fifth aspect of the present invention is In the method for disposing of a container according to the first aspect, the step of attaching the release plug is carried out while the temperature of the container is maintained below the melting point of the deleterious or poisonous substance.

[0012] A sixth aspect of the present invention is In the method for disposing of containers according to the first aspect, the heating step involves storing the container in a metal can filled with a non-combustible buffer material and heating the container.

[0013] A seventh aspect of the present invention is The method for disposing of containers according to the first aspect further comprises a step of treating exhaust gas generated in the heating step in a secondary combustion furnace. [Effects of the Invention]

[0014] According to one embodiment of the present invention, a container that has contained a water-resistant deleterious or poisonous substance can be disposed of safely and easily. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a flowchart showing an example of a container disposal method according to a first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Details of the embodiment of the present invention] An embodiment of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0017] <First embodiment of the present invention> (1) Disposal method of container First, the container disposal method of this embodiment will be described. FIG. 1 is a flowchart showing an example of the container disposal method of this embodiment. As shown in FIG. 1, the container disposal method of this embodiment includes, for example, an open-plug attachment step S110, a valve opening step S120, and a heating step S130. Furthermore, after the heating step S130, an exhaust gas treatment step S140 may be performed as necessary. In the present invention, the "open plug" refers to a part that can be attached to the opening of a container, is in a closed state when attached, but opens when the pressure inside the container reaches a certain level or higher.

[0018] The containers targeted for disposal in this embodiment are waste cylinders and other containers that contained water-resistant deleterious or toxic substances (hereinafter simply referred to as deleterious substances). Examples of water-resistant deleterious or toxic substances include substances containing superacids, which are acids stronger than 100% sulfuric acid. Here, "water-resistant" refers to the property of igniting, generating heat, or generating flammable or harmful gases upon contact with water. This embodiment describes the disposal of a container that contained antimony pentafluoride, a superacid. Antimony pentafluoride reacts violently with water to produce hydrogen fluoride, a substance that is extremely harmful and dangerous to humans. Therefore, it is necessary to safely dispose of the container without exposing the deleterious substances contained in the container to moisture in the air. Other substances subject to this waste disposal method include molybdenum hexafluoride and iodine pentafluoride.

[0019] The container to be disposed of in this embodiment is, for example, a small waste cylinder, the capacity of which is, for example, 500 mL or less. Therefore, in this embodiment, the release cap attachment step S110 and the valve opening step S120, which will be described later, can be performed in a glove box or the like. Note that the above operations can be performed in a glove box for waste cylinders up to 2 L in volume.

[0020] In this embodiment, for example, it is not necessary to check whether or not a deleterious substance is present in the container or the amount of the deleterious substance remaining. The container disposal method of this embodiment can be used regardless of whether or not the container has contents, thereby simplifying the process. For example, about 5 to 6 500 mL containers can be stored in a glove box and processed at one time.

[0021] (Release valve installation step S110) The release plug attachment step S110 is, for example, a step of attaching a plug to the valve opening of the container that opens when a pressure less than the pressure test pressure of the container is applied. In this embodiment, a case will be described in which a relief valve is attached to the valve opening of the container as the release plug. A relief valve is a valve equipped with a mechanism that opens in proportion to the increase in pressure when the pressure on the upstream side (in this case, inside the container) exceeds a set value, and then closes again when the pressure falls below the set value. Note that if the diameters of the valve opening of the container and the relief valve do not match, the relief valve may be attached to the valve opening via an appropriate joint.

[0022] The containers targeted for disposal in this embodiment are containers that contained water-resistant deleterious substances, and for safety reasons, they rarely have relief valves or safety valves attached. In this embodiment, the relief valve is used not as a safety device to prevent accidents such as the container exploding in the event of an abnormal pressure increase, but as a stopper to safely and easily release any deleterious substances remaining in the container inside the heating furnace.

[0023] The relief valve used can be a commercially available one. In the release plug attachment step S110, it is preferable to attach a relief valve to the valve port that opens at a pressure of 0.5 times or less the pressure test pressure of the container. It is more preferable to use a release plug that opens at a pressure of 1 MPa or less, and it is particularly preferable to use a release plug that opens at a pressure of 0.5 MPa or less. This prevents the container from opening before the heating step S130, and makes it possible to safely and easily open the container in the heating step S130.

[0024] The release plug attachment step S110 is preferably performed in a sealed container (e.g., in a glove box) in an inert gas atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere). The containers to be disposed of in this embodiment are small waste cylinders as described above, and the work can be easily performed by placing the container in a glove box. This allows the release plug attachment step S110 and the valve opening step S120 to be performed without the deleterious substances in the container coming into contact with moisture in the air, enabling safer processing.

[0025] The release stopper attachment step S110 is preferably performed while the temperature of the container is maintained below the melting point of the deleterious substance inside the container. Specifically, the work can be performed by setting the temperature inside the glove box below the melting point of the deleterious substance. In this embodiment, the temperature can be set to below 8.3°C, the melting point of antimony pentafluoride, so temperature setting is relatively easy. This causes the deleterious substance inside the container to become solid, making the release stopper attachment step S110 safer.

[0026] (Valve opening process S120) The valve opening step S120 is, for example, a step of opening the valve port of a container with a relief valve attached to the container. Even when the valve port is opened, the relief valve keeps the container sealed, preventing the substance inside the container from coming into contact with moisture in the air. Like the release plug attachment step S110, the valve opening step S120 is preferably performed in a sealed container (in a glove box) with an inert gas atmosphere, and the temperature of the container is preferably maintained below the melting point of the deleterious substance inside the container. Furthermore, before or after opening the valve port of the container, it is preferable to place the container in a flammable polyethylene (PE) bag or the like and seal it. This prevents a large amount of deleterious substance from being released all at once, even if the relief valve is opened before the container is placed in a heating furnace.

[0027] (Heating process S130) The heating step S130 is, for example, a step in which a relief valve is attached to the container, the container is placed in a heating furnace with the valve opening open, and the container is heated to a temperature above the boiling point of the deleterious substance inside the container. When the container is heated and the internal pressure of the container exceeds the set pressure of the relief valve, the relief valve opens, and the deleterious substance inside the container is gradually released and thermally decomposed. This allows the deleterious substance inside the container to be safely disposed of. Note that there are no particular limitations on the type of heating furnace used in the heating step S130, but it is preferable to use a batch-type heating furnace, which makes it easy to control the heating temperature and temperature rise rate.

[0028] Furthermore, in the heating step S130, it is preferable to store the container (encased in a PE bag) in a metal can (e.g., a pail) filled with non-combustible buffer material (e.g., vermiculite). It is preferable not to seal the pail. This stabilizes the position of the container during heating and reduces the oxygen around the container, allowing for safe heating. Furthermore, in the heating step S130, it is preferable to place the pail containing the container in a metal can (e.g., a drum) before heating. This allows for safer heating.

[0029] In the heating step S130, the temperature of the heating furnace is gradually increased, allowing the material to be released from the container into the furnace without a sudden rise in internal pressure after the relief valve is opened. For example, it is preferable to hold the material at a temperature slightly higher than the boiling point for about 0.5 to 1 hour, then set the furnace temperature to 600°C or higher and 1000°C or lower, and heat for 0.5 to 2 hours. Specifically, the temperature and time can be set depending on the type of deleterious substance to be treated, the amount of container to be treated, etc.

[0030] (Exhaust gas treatment process S140) Furthermore, if the hazardous substances remaining in the container are completely decomposed and rendered harmless in the heating step S130, this is not necessary, but if exhaust gas that requires treatment is generated, it is preferable to further perform the exhaust gas treatment step S140 and treat the exhaust gas in a secondary combustion furnace.

[0031] Specifically, for example, the generated exhaust gas is subjected to a secondary combustion step S141, and if necessary, a rapid cooling step S142, a dust removal and desalination step S143, and a soot and dust treatment step S144. The exhaust gas discharged from the heating furnace during heating in the heating step S130 is first introduced into a secondary combustion furnace, where it is burned at a high temperature of 800°C or higher for a predetermined time (e.g., 2 seconds or more), thereby rendering the exhaust gas discharged from the container harmless. If there is any cinders discharged during secondary combustion, they can be treated separately.

[0032] The exhaust gas after secondary combustion is introduced into a heat exchanger, where it undergoes heat exchange with feed air from a blower provided in association with the heat exchanger, and can then be sent to a downstream quench tower. Here, the feed air used for the heat exchange may be introduced into the heating furnace as combustion air after heat exchange. In the quench tower, the exhaust gas is rapidly cooled, for example, by heat exchange with cooling water, and the cooled exhaust gas is sent to a downstream dust collector. Rapid cooling of the exhaust gas protects the dust collector and exhaust fan located downstream of the quench tower from heat damage, thereby improving the life of the equipment. Here, when the exhaust gas is introduced from the quench tower to the dust collector, chemicals such as hydrated lime or activated carbon may be added from a supply unit, if necessary.

[0033] <Other Embodiments of the Present Invention> Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the invention.

[0034] For example, in the above-described embodiment, a case where a relief valve is attached to the valve opening of the container is described, but the stopper attached to the valve opening is not limited to a relief valve. Specifically, a safety valve equipped with a mechanism that opens when a certain pressure is reached and does not close thereafter may also be used. However, from the viewpoint of gradually releasing the deleterious substance in the container and performing treatment more safely, it is preferable to use a relief valve equipped with a mechanism that opens in proportion to an increase in pressure and then closes again, as in the above-described embodiment. [Example]

[0035] Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0036] In this example, a small waste cylinder containing antimony pentafluoride, a superacid, was disposed of. The volume of this waste cylinder was 400 mL, the content at the time of sale was 100 g, and the pressure test pressure was 3.2 MPa. Antimony pentafluoride remained in the waste cylinder.

[0037] First, the waste cylinder was placed in a glove box, and the inside of the glove box was filled with an inert gas atmosphere. The temperature inside the glove box was set to be less than 8.3°C, which is the melting point of antimony pentafluoride. Then, a relief valve (manufactured by Kinki Seisakusho, model number NO210RV, set pressure 0.2 MPa) was attached to the cylinder mouth of the waste cylinder inside the glove box. After the relief valve was attached, the valve mouth of the container was opened.

[0038] The waste cylinder was then removed from the glove box and the container was packed in a double ziplock PE bag. The packed waste cylinder was placed in a pail and vermiculite was filled into the gaps to prevent the waste cylinder from moving. A hole was made in the lid of the pail to prevent it from being airtight. The pail containing the cylinder was then placed in a drum and placed in a heating furnace.

[0039] The heating furnace was heated to 800°C over 1 hour after loading, and then heated for 0.5 hours. After heating was completed, the container was removed from the furnace and checked for any abnormalities such as rupture. The relief valve attached to the container was also removed and it was confirmed that the contents were completely empty.

[0040] From the above, it was confirmed that the method described in the first embodiment of the present invention allows safe and easy disposal of containers that have contained water-resistant deleterious or poisonous substances. [Explanation of symbols]

[0041] S110 Release valve installation process S120 Valve opening process S130 Heating process S140 Exhaust gas treatment process S141 Secondary combustion process S142 Rapid cooling process S143 Dust removal / desalination process S144 Soot and dust treatment process

Claims

1. A method for disposing of containers that have contained water-resistant deleterious or poisonous substances, comprising the steps of: an attachment step of an open plug that is attached to the valve opening of the container and that is in an open state when subjected to a pressure that is less than the pressure test pressure of the container; and a step of heating the container with the stopper attached in a heating furnace.

2. 2. The method for disposing of containers according to claim 1, wherein the deleterious or toxic substance includes a superacid, which is an acid stronger than 100% sulfuric acid.

3. 2. The method for disposing of a container according to claim 1, wherein the plug is a relief valve that opens when a pressure equal to or less than 0.5 times the pressure test pressure of the container is applied.

4. 2. The method for disposing of a container according to claim 1, wherein the step of attaching the release plug is performed in a sealed container under an inert gas atmosphere.

5. 2. The method for disposing of containers according to claim 1, wherein the step of attaching the release plug is performed while the temperature of the container is maintained below the melting point of the deleterious or poisonous substance.

6. 2. The method for disposing of containers according to claim 1, wherein the heating step involves heating the containers while they are housed in a metal can filled with a non-combustible buffer material.

7. 2. The method for disposing of containers according to claim 1, further comprising a step of treating exhaust gas generated in the heating step in a secondary combustion furnace.

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