JP2007295942A - Treatment agent for asbestos-containing material and treating method of asbestos-containing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment agent capable of preventing asbestos from scattering from an asbestos-containing material and easily detoxicating the asbestos incorporated in the asbestos-containing material when disposing the asbestos-containing material. <P>SOLUTION: The treatment agent for asbestos-containing material contains polyvinyl alcohol, water-soluble calcium salt and water dissolving them. When the asbestos-containing material such as a concrete wall, on which the asbestos is sprayed, is broken down after applying the treatment agent, the scattering of the asbestos is prevented. Also, the asbestos-containing material broken down in such a manneris detoxified only by being subjected to heat treatment at 400-800°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a treatment for asbestos-containing materials and a method for treating asbestos-containing materials, and particularly relates to an aqueous treatment agent for asbestos-containing materials and a method for treating asbestos-containing materials using the same.

  Asbestos (asbestos) is a fibrous compound in which silica (silicon oxide) and magnesium are bonded, and has properties such as flexibility, heat resistance, and chemical inertness. It has been widely used as a useful spraying material for concrete walls as a material to be applied, but it has been revealed that it causes health damage to the human body, causing asbestosis, lung cancer and mesothelioma. Currently, its use is prohibited. In addition, since old buildings using asbestos may be scattered into the atmosphere due to deterioration, the removal of asbestos and the dismantling of the building itself are being promoted. However, asbestos is a fibrous material as described above, and is lightweight, so it is scattered during removal work from concrete walls and building demolition work, and is healthy for workers and nearby residents. There is a high possibility of causing damage. Therefore, measures have been studied to peel off or disassemble the asbestos spray layer safely without scattering the asbestos in the asbestos-containing material such as a concrete wall sprayed with asbestos.

  Patent Document 1 relates to a method for preventing dust of asbestos from being scattered, and this method includes a water retention agent such as starch and polyvinyl alcohol and a thickener such as cellulose and polyvinyl alcohol. The medicine which mixed two types of components as an essential component is apply | coated and cured with respect to an asbestos containing material, and the asbestos containing material is removed after that. It is thought that the chemical | medical agent used here osmose | permeates into an asbestos containing material, and fixes asbestos, As a result, it is thought that scattering of asbestos can be prevented.

  However, the method described in Patent Document 1 can only prevent the asbestos from scattering, and does not assume the detoxification of the asbestos-containing material. Therefore, the asbestos-containing material removed by the application of the method needs to detoxify asbestos separately. However, for that purpose, it is necessary to heat and melt the asbestos-containing material to a high temperature of about 1,500 ° C., which requires a special device and implementation environment, which is difficult to implement and expensive.

  On the other hand, as a method for detoxifying asbestos, Non-Patent Document 1 describes a method of heating an asbestos-containing material together with a compound containing calcium. In this method, a chemical reaction between calcium and silica proceeds at a relatively low temperature of about 600 to 700 ° C. As a result, silica and magnesium constituting asbestos are separated. And the asbestos-containing material can be easily rendered harmless at a low cost.

  However, the method described in Non-Patent Document 1 can only detoxify the asbestos-containing material and can prevent the asbestos from being scattered when the asbestos-containing material is removed or disassembled. is not.

Japanese Patent Laid-Open No. 10-323614 Nikkei Ecology, December 2005, page 57

  An object of the present invention is to dispose of an asbestos-containing treatment agent that can prevent asbestos from being scattered from the asbestos-containing material and can easily detoxify the asbestos contained in the asbestos-containing material. It is to be realized.

  The treatment agent for asbestos-containing materials of the present invention contains polyvinyl alcohol, a water-soluble calcium salt, and water in which these polyvinyl alcohol and calcium salt are dissolved.

  This treatment agent penetrates when applied to the asbestos-containing material, and fixes asbestos on the surface and inside of the asbestos-containing material by the interaction between the polyvinyl alcohol and the calcium salt. For this reason, the asbestos-containing material to which this treatment agent is applied is less likely to scatter the asbestos into the environment even when subjected to a destructive action during dismantling work. In addition, when the asbestos-containing material to which this treatment agent is applied is heated as it is, a chemical reaction between the calcium element derived from the calcium salt and the silica constituting the asbestos proceeds, and the asbestos is separated into silica and magnesium, which is harmless. It becomes.

  This treatment agent for asbestos-containing materials usually has a polyvinyl alcohol concentration of 0.1 to 20% by weight and a calcium salt concentration of 0.1 to 3% by weight in terms of calcium. Polyvinyl alcohol usually has a polymerization degree of 200 to 1,000 and a saponification degree of 80 to 94%. Furthermore, the calcium salt used here is usually at least one of calcium chloride and calcium nitrate.

  The method for treating an asbestos-containing material according to the present invention is a step of applying a treatment agent containing polyvinyl alcohol, a water-soluble calcium salt, and water dissolving these polyvinyl alcohol and calcium salt to the asbestos-containing material, Disassembling the asbestos-containing material to which the treatment agent is applied. Moreover, this dismantling method usually further includes a step of heat-treating the disassembled asbestos-containing material at 400 to 800 ° C.

  In this treatment method, when the treatment agent is applied to the asbestos-containing material, the treatment agent penetrates into the asbestos-containing material. The infiltrated treatment agent fixes asbestos on the surface and inside of the asbestos-containing material by the interaction between polyvinyl alcohol and calcium salt. For this reason, if the asbestos-containing material is disassembled after this step, the asbestos-containing material is unlikely to scatter the asbestos into the environment even if it receives a destructive action during the dismantling operation. Further, when the asbestos-containing material disassembled after the treatment agent is applied is heated as it is in the above temperature range, the chemical reaction between the calcium element derived from the calcium salt and the silica constituting the asbestos proceeds, and the asbestos becomes silica. And separated into magnesium and detoxified.

  The other processing method of the asbestos-containing material according to the present invention is a step of applying a treatment agent containing polyvinyl alcohol, a water-soluble calcium salt, and water dissolving these polyvinyl alcohol and calcium salt to the asbestos-containing material. And a step of heat-treating the asbestos-containing material coated with the treatment agent at 400 to 800 ° C.

  In this treatment method, when the treatment agent is applied to the asbestos-containing material, the treatment agent penetrates into the asbestos-containing material. The infiltrated treatment agent fixes asbestos on the surface and inside of the asbestos-containing material by the interaction between polyvinyl alcohol and calcium salt. Then, when the asbestos-containing material is heated in the above temperature range after this step, the asbestos stays in the asbestos-containing material without scattering, and a chemical reaction between the calcium element derived from the calcium salt and the silica constituting the asbestos proceeds. Then, it is separated into silica and magnesium and rendered harmless.

  Since the treatment agent for asbestos-containing material according to the present invention is composed of the above-mentioned components, when disposing of the asbestos-containing material, it can prevent the asbestos from scattering from the asbestos-containing material, and the asbestos-containing material Asbestos contained in can be easily detoxified.

  Since the processing method of the asbestos-containing material according to the present invention uses the above-described processing agent according to the present invention, the asbestos-containing material can be disassembled while preventing the asbestos from being scattered, and disassembled as necessary. Asbestos contained in the later asbestos-containing material can be easily detoxified.

  Since the processing method of the asbestos-containing material according to the present invention uses the above-described processing agent according to the present invention, the asbestos contained in the asbestos-containing material can be easily detoxified while preventing the asbestos from scattering.

  The treatment agent for asbestos-containing materials of the present invention is in the form of an aqueous solution containing polyvinyl alcohol, a water-soluble calcium salt, and water in which these are dissolved.

  Various commercially available polyvinyl alcohols can be used, but those having a polymerization degree of 200 to 1,000 are preferred. When the degree of polymerization is less than 200, the asbestos-containing material to which the treatment agent of the present invention is applied is not easily fixed because the crushing strength is insufficient, and asbestos is difficult to be fixed. It may be easy to do. On the contrary, when the degree of polymerization exceeds 1,000, the treatment agent of the present invention hardly penetrates into the asbestos-containing material, so it takes a long time to treat the asbestos-containing material using the treatment agent. Depending on the case, there is a possibility that the asbestos fixing effect by the treatment agent becomes insufficient and asbestos scattering cannot be effectively prevented. The degree of polymerization here is an average degree of polymerization measured based on Japanese Industrial Standard JIS K6726 (1994) “Testing method of polyvinyl alcohol”.

  The polyvinyl alcohol preferably has a saponification degree of 80 to 94%. When the degree of saponification is outside this range, the treatment agent of the present invention hardly penetrates into the asbestos-containing material, so that it takes a long time to treat the asbestos-containing material using the treatment agent. There is a possibility that the asbestos fixing effect by the agent becomes insufficient and the scattering of asbestos cannot be effectively prevented. The degree of saponification here is measured based on Japanese Industrial Standard JIS K6726 (1994) “Testing method of polyvinyl alcohol”.

  Incidentally, in the treatment agent of the present invention, the polymerization degree and saponification degree of polyvinyl alcohol can be appropriately selected according to the permeability of the treatment agent of the present invention to asbestos-containing materials.

On the other hand, various calcium salts can be used as long as they are water-soluble and have high solubility in water. Specifically, calcium chloride (CaCl ₂ ) or calcium nitrate (Ca (NO ₃ ) ₂ ) is preferably used, and these can be used in combination. These calcium salts not only have high solubility in water, but also can maintain the treatment agent at approximately neutrality, so there is little possibility of decomposing and modifying polyvinyl alcohol in the treatment agent, and also contain asbestos Since the possibility of harming the work environment when spraying the treatment agent on the object is small, the stability and safety of the treatment agent can be achieved.

  Incidentally, the calcium salt forms a hardly soluble salt when added to an aqueous solution of a water-soluble polymer other than polyvinyl alcohol, for example, an aqueous solution of sodium alginate or sodium silicate. No salt is formed. Therefore, the treatment agent of the present invention has good applicability to asbestos-containing materials and can be applied uniformly.

  Here, calcium salts other than those in the above specific examples may be used, but calcium sulfate (gypsum) having low solubility in water is not suitable for the treatment agent of the present invention.

  In the treatment agent of the present invention, the concentration of polyvinyl alcohol is usually preferably set to 0.1 to 2% by weight. When this concentration is less than 0.1% by weight, the asbestos-containing material to which the treatment agent of the present invention is applied is likely to collapse due to insufficient crushing strength. , Asbestos may be scattered easily. On the other hand, if it exceeds 2% by weight, the treatment agent of the present invention hardly penetrates into the asbestos-containing material, so that it takes a long time to treat the asbestos-containing material using the treatment agent. There is a possibility that the asbestos fixing effect by the agent becomes insufficient and the scattering of asbestos cannot be effectively prevented.

  The concentration of the calcium salt is usually preferably 0.1 to 3% by weight in terms of calcium (that is, in terms of calcium element). If this concentration is less than 0.1% by weight, it may not be possible to sufficiently prevent the asbestos contained in the asbestos-containing material from scattering, and the asbestos contained in the asbestos-containing material may not be sufficiently harmless. is there. Conversely, if it exceeds 3% by weight, the asbestos detoxification effect proportional to the concentration cannot be obtained, which is uneconomical.

Next, the processing method of the asbestos containing material using the processing agent of this invention is demonstrated.
The asbestos-containing material that can be treated using the treatment agent of the present invention is not particularly limited. For example, a gypsum board used for a slate board, a factory roof (slate corrugated board) material, an outer wall, an interior, a floor, and the like. Asbestos-containing insulation materials such as fireproof covering plates that cover steel pillars, insulation materials used as building materials containing asbestos such as steel and cement boards and floor tiles, pipes, fireproof covering plates that cover steel columns, and asbestos were sprayed A concrete surface such as a concrete wall or ceiling has permeability of the treatment agent.

  When the asbestos-containing material is a building material used in a concrete surface or building of a building, and the entire building is destroyed or the asbestos-containing material part is partially destroyed and removed ( In the present application, destroying or removing asbestos-containing material is collectively referred to as “disassembly”), and the above-described treatment agent is applied to the asbestos-containing material. The treatment agent can be applied using various coating tools such as rollers, sprays, brushes, and irons.

  Here, the asbestos-containing material coated with the treatment agent is usually left to stand for several hours and dried. At this time, the treatment agent applied to the asbestos-containing material penetrates from the surface of the asbestos-containing material to the inside. And the asbestos which exists in the surface and inside of an asbestos containing material is fixed in the surface and inside of an asbestos containing material by interaction with the polyvinyl alcohol and calcium salt which are contained in a processing agent.

  Next, the asbestos-containing material is disassembled. Here, asbestos contained in the asbestos-containing material is fixed by the action of the treatment agent as described above, so it is difficult to peel off from the surface, and the asbestos-containing material is broken and separated into a large number of asbestos-containing material pieces. Even it is held in each piece. That is, asbestos contained in the asbestos-containing material is difficult to be dusted when the asbestos-containing material is disassembled, and scattering into the environment is prevented. Therefore, according to this method, the asbestos-containing material can be safely disassembled.

  The asbestos-containing material that has been disassembled, for example, the above-mentioned many asbestos-containing material pieces, is usually subjected to asbestos detoxification treatment. Here, the asbestos-containing material after dismantling is put into a heating furnace and heat-treated at 400 to 800 ° C. In this heat treatment, asbestos in the asbestos-containing material undergoes a chemical reaction between the constituent silica and calcium element derived from the calcium salt in the treatment agent, and is separated into silica and magnesium to be rendered harmless. . Therefore, the asbestos-containing material after the detoxification treatment can be safely discarded.

  On the other hand, if the asbestos-containing material is a building material that has already been removed from the building, or a building piece that has not been used, and a concrete piece that has been generated by the dismantling of the building, there is no need for dismantling again. Asbestos contained in the asbestos-containing material can be safely rendered harmless.

  In this case, first, the treatment agent of the present invention is applied to the asbestos-containing material by the method as described above, and left as it is for several hours to dry. Thereby, the asbestos contained in the surface and inside of the asbestos-containing material is fixed to the asbestos-containing material, and scattering is prevented. Next, the asbestos-containing material coated with the treatment agent is put into a heating furnace and heat-treated at 400 to 800 ° C. In this heat treatment, asbestos in the asbestos-containing material is detoxified by separating into silica and magnesium as described above. Therefore, according to such a processing method, the asbestos-containing material can be rendered harmless while preventing the asbestos from being scattered, and the asbestos-containing material after the detoxification treatment can be safely discarded.

Reference example 1
Five types of polyvinyl alcohols having different degrees of polymerization (the degree of saponification is 85%) are used. The concentration of polyvinyl alcohol is 0.1% by weight and the concentration of calcium chloride is 0.5% by weight (0.18% by weight in terms of calcium). 5 types of aqueous solutions (treatment agents) were prepared. Then, 10 milliliters of pulverized asbestos-containing material (slate corrugated plate) is put into a cylindrical container having an inner diameter of 10 mm, and 1 milliliter of the treatment agent is added on the pulverized material so that the entire amount penetrates into the pulverized material. Time was measured. The results are shown in FIG. In FIG. 1, the permeation time (relative value) is a relative value when the permeation time is 100 when the polymerization degree of polyvinyl alcohol is 2,000. According to FIG. 1, it is apparent that the treatment agent has a rapid delay in permeation time when polyvinyl alcohol having a polymerization degree exceeding 1,000 is used. According to this result, the polymerization degree of polyvinyl alcohol used in the treating agent is preferably 1,000 or less.

Reference example 2
For the asbestos-containing material (slate corrugated sheet), among the five types of treatment agents prepared in Reference Example 1, four types using polyvinyl alcohol having a polymerization degree of 1,000 or less were individually applied, and at room temperature for 5 hours. Dried. And the crushing strength was measured about the asbestos containing material processed in this way. The crushing strength here is the maximum stress per unit area at the time of crushing measured with a force gauge (“AD-4932A-50N” of A & D Co., Ltd.), and the polymerization degree of polyvinyl alcohol is 1,000. It is a relative value when the crushing strength is 100. The results are shown in FIG. According to FIG. 2, the crushing strength is stable when the degree of polymerization of polyvinyl alcohol is in the range of 200 to 1,000. According to this result, the polymerization degree of polyvinyl alcohol used in the treating agent is preferably 200 or more.

Reference example 3
Seven types of polyvinyl alcohol having different saponification degrees (all polymerization degrees are 200), the polyvinyl alcohol concentration is 0.1% by weight, and the calcium chloride concentration is 0.5% by weight (calculated in terms of 0.18% by weight). 7 aqueous solutions (treatment agents) were prepared. Then, the penetration time was measured for each treatment agent in the same manner as in Reference Example 1. The results are shown in FIG. In FIG. 3, the permeation time (relative value) is a relative value when the permeation time is 100 when the saponification degree of polyvinyl alcohol is 87%. According to FIG. 3, it is apparent that the treatment agent has a rapid delay in permeation time when polyvinyl alcohol having a saponification degree of less than 80% and more than 94% is used. According to this result, the saponification degree of polyvinyl alcohol used in the treatment agent is preferably 80 to 94%.

Reference example 4
Four types of aqueous solutions (treatment agents) using polyvinyl alcohol having a polymerization degree of 200 and a saponification degree of 85%, a calcium chloride concentration of 0.5% by weight (calculated as 0.18% by weight) and different polyvinyl alcohol concentrations Was prepared. And these processing agents were apply | coated separately with respect to the asbestos containing material (slate corrugated sheet), and it dried at room temperature for 5 hours. The crushing strength of the asbestos-containing material thus treated was measured in the same manner as in Reference Example 2. This crushing strength is a relative value when the crushing strength when the polyvinyl alcohol concentration is 5% by weight is defined as 100. The results are shown in FIG. According to FIG. 4, the crushing strength rapidly decreases when the concentration of polyvinyl alcohol is less than 0.1% by weight. According to this result, the concentration of polyvinyl alcohol in the treatment agent is preferably 0.1% by weight or more.

Reference Example 5
Five types of aqueous solutions (treatment agents) using polyvinyl alcohol having a polymerization degree of 200 and a saponification degree of 85%, a calcium chloride concentration of 0.5% by weight (calculated in terms of 0.18% by weight) and different polyvinyl alcohol concentrations Was prepared. Then, the penetration time was measured for each treatment agent in the same manner as in Reference Example 1. The results are shown in FIG. In FIG. 5, the permeation time (relative value) is a relative value when the permeation time is 100 when the polyvinyl alcohol concentration is 3% by weight. According to FIG. 5, it is clear that the treatment agent has a rapid delay in permeation time when the polyvinyl alcohol concentration exceeds 2% by weight. According to this result, the polyvinyl alcohol concentration in the treatment agent is preferably 2% by weight or less.

Reference Example 6
Polyvinyl alcohol having a polymerization degree of 200 and a saponification degree of 85% was used, and seven types of aqueous solutions (treatment agents) having a polyvinyl alcohol concentration of 0.1% by weight and different calcium chloride concentrations (calcium conversion) were prepared. Then, 5 g of these treatment agents were individually added to 20 g of the asbestos-containing material (slate corrugated plate), and heat-treated at 700 ° C. for 2 hours, and the decomposition rate of asbestos was examined. The decomposition rate was determined from the change in peak intensity by measuring the peak intensity by X-ray diffraction. The results are shown in FIG. According to FIG. 6, the decomposition rate is remarkably lowered when the calcium chloride concentration (calcium conversion) is less than 0.1% by weight, and is approximately 100% when the concentration is 0.1% by weight or more. According to this result, the calcium chloride concentration in the treating agent is preferably set in a range of about 0.1 to 3% by weight in terms of calcium.

Reference Example 7
Polyvinyl alcohol having a polymerization degree of 200 and a saponification degree of 85% was used, and five types of aqueous solutions (treatment agents) having a polyvinyl alcohol concentration of 0.1% by weight and different calcium chloride concentrations (calcium conversion) were prepared. And these processing agents were apply | coated separately with respect to the asbestos containing material (slate corrugated sheet), and it dried at room temperature for 5 hours. The crushing strength of the asbestos-containing material thus treated was measured in the same manner as in Reference Example 2. This crushing strength is a relative value when the crushing strength when the calcium chloride concentration (calcium conversion) is 10% by weight is defined as 100. The results are shown in FIG. According to FIG. 7, the crushing strength increases as the calcium chloride concentration (calcium conversion) increases, but does not change greatly even if the concentration exceeds 3% by weight. According to this result, the calcium chloride concentration in the treating agent is considered to be sufficient even if it is 3% by weight or less in terms of calcium.

Comparative Example 0.6 liters of water was uniformly applied to 1 m ^{2 of} asbestos-containing spray material (asbestos content = 4.2% by weight) sprayed on the walls of the building and dried at room temperature for 5 hours. Then, the asbestos-containing spray material was removed from the wall while being destroyed. At this time, when the asbestos concentration in the work was measured by the method prescribed in “Measurement method of specific dust concentration related to asbestos” (December 27, 1989, Environment Agency Notification No. 93), 220 fibers / It was 10 liters / liter, which is the boundary standard for the Air Pollution Control Law.

Example 1
An aqueous solution (treatment agent) having a concentration of polyvinyl alcohol (polymerization degree = 600, saponification degree = 85%) of 0.5% by weight and calcium chloride concentration of 0.5% by weight (calculated 0.18% by weight). Prepared. When this treatment agent was used in place of water under the same conditions as in the comparative example and removed in the same manner as in the comparative example, the environmental concentration of asbestos during the operation was 0.8 fiber / liter, and the site of the Air Pollution Control Law It was well below the boundary standard of 10 fibers / liter.

  Next, the removed asbestos-containing corrugated slate plate pieces were collected, put into a heating furnace, and heat-treated at 700 ° C. for 2 hours. The asbestos content of the asbestos-containing corrugated sheet slate plate after the heat treatment was measured by X-ray diffraction. Asbestos decomposition rate was about 100% (residual asbestos content was 0.2% by weight or less of the detection limit). Met.

Example 2
A treatment agent similar to that of Example 1 was prepared except that the polyvinyl alcohol concentration was changed to 0.05% by weight. When this removal agent was used to remove the same as in the comparative example, the environmental concentration of asbestos during the work was 65 fibers / liter, exceeding 10 fibers / liter, which is the site boundary standard for the Air Pollution Control Law. However, the asbestos scattering was significantly suppressed as compared with the comparative example.

Example 3
A treatment agent similar to that of Example 1 was prepared, except that the calcium chloride concentration was changed to 0.14% by weight (0.05% by weight in terms of calcium). When this removal agent was used for removal work similar to the comparative example, the environmental concentration of asbestos during the work was 0.9 fibers / liter, which was below the 10 fiber / liter, which is the site standard for the Air Pollution Control Law. It was.

  Next, the removed asbestos-containing corrugated slate plate pieces were collected, put into a heating furnace, and heat-treated at 700 ° C. for 2 hours. And about the asbestos content corrugated slate board piece after heat processing, when the asbestos content was measured by X-ray diffraction, the decomposition rate of asbestos was 55% (residual asbestos amount was 1.9 weight%).

The graph which shows the result of the reference example 1. The graph which shows the result of the reference example 2. The graph which shows the result of the reference example 3. The graph which shows the result of the reference example 4. The graph which shows the result of the reference example 5. The graph which shows the result of the reference example 6. The graph which shows the result of the reference example 7.

Claims (7)

Polyvinyl alcohol,
Water-soluble calcium salt,
Water dissolving the polyvinyl alcohol and the calcium salt;
A processing agent for asbestos-containing materials.   The treatment agent for asbestos-containing materials according to claim 1, wherein the polyvinyl alcohol concentration is 0.1 to 2% by weight, and the calcium salt concentration is 0.1 to 3% by weight in terms of calcium.   The treatment agent for asbestos-containing materials according to claim 1 or 2, wherein the polyvinyl alcohol has a polymerization degree of 200 to 1,000 and a saponification degree of 80 to 94%.   The treatment agent for asbestos-containing materials according to any one of claims 1 to 3, wherein the calcium salt is at least one of calcium chloride and calcium nitrate. Applying a treatment agent containing polyvinyl alcohol, a water-soluble calcium salt, and water dissolving the polyvinyl alcohol and the calcium salt to asbestos-containing materials;
Disassembling the asbestos-containing material coated with the treatment agent;
Of processing asbestos-containing materials including   The processing method of the asbestos containing material of Claim 5 which further includes the process of heat-processing the disassembled said asbestos containing material at 400-800 degreeC. Applying a treatment agent containing polyvinyl alcohol, a water-soluble calcium salt, and water dissolving the polyvinyl alcohol and the calcium salt to asbestos-containing materials;
A step of heat-treating the asbestos-containing material coated with the treatment agent at 400 to 800 ° C .;
Of processing asbestos-containing materials including

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