JPH0512307B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an asbestos modification treatment agent and treatment method, and more specifically, it relates to an asbestos modification treatment agent and a treatment method, and more specifically, it is mainly used for asbestos treatment for walls, ceilings, etc. of building structures that are treated as industrial waste. The present invention relates to a treatment agent and a treatment method for modifying and rendering harmless asbestos-containing materials that are no longer needed, such as sprayed asbestos, slate boards, brake shoes, etc.

[Conventional technology] Asbestos includes white asbestos (chrysotile,
In addition to asbestos (mainly composed of MgO and SiO ₂ ), there is also a small amount of tea asbestos (amosaite, Fe ₂ O ₃ ,
SiO ₂ as the main component), blue asbestos (crocidolite, Fe ₂ O ₃ / SiO ₂ as the main component), etc. are also used, and they have properties such as fire resistance, durability, heat insulation, and abrasion resistance. It has excellent properties as a natural fiber with advantages. For this reason, such asbestos has been widely used in construction-related fields as molded plates or as sprayed materials such as fireproof coatings, sound-absorbing materials, and heat-insulating materials.

However, such asbestos causes the generation of acicular fiber dust, and it has been found that when this acicular fiber becomes dust and is taken into the human body, it has an adverse effect on health, and this asbestos pollution has become a major social problem. It's here.

For this reason, the idea of removing and disposing of the asbestos-containing materials that have already been used has arisen, and the asbestos-containing materials that have been removed and become waste are packed in bags or concrete and buried in the soil. Several methods have been tried, such as burying the

However, when asbestos-containing materials are disposed of in this way, there is a possibility that they may be exposed from the soil to the surface due to some chance, such as an earthquake, and turn into dust again, causing pollution. In some cases, the disposal of asbestos-containing materials using this method has been banned. For this reason, how to treat asbestos-containing materials into harmless substances has become a major issue.

By the way, asbestos is a chemically extremely stable substance that does not dissolve in ordinary acids except hydrofluoric acid, and was thought to be extremely difficult to modify chemically. Therefore, no attempt has been made to chemically modify this asbestos, and the reality is that no fundamental solution has been reached regarding the treatment of asbestos.

[Problems to be Solved by the Invention] Therefore, the present inventors focused on the fact that asbestos is a basic substance, and found that the basic component contained in asbestos also reacts with MgO and Fe ₂ O ₃ . From the viewpoint of whether it is possible to chemically or physically destroy the SiO ₂ or the SiO ₂ and MgO or Fe ₂ O ₃ compounds that are thought to cover the surface of asbestos,
The present invention was arrived at as a result of intensive studies on various substances.

Therefore, an object of the present invention is to provide an asbestos modification treatment agent that can chemically modify asbestos itself and render it harmless.

Another object of the present invention is to provide a method for modifying asbestos, which uses such a modifying agent to chemically modify asbestos and render it harmless.

[Means for Solving the Problems] In other words, the present invention provides a solution to a mixture of one or more acids having one or more elements of sulfur, nitrogen, or halogen, and an aqueous inorganic polymer compound. It is an asbestos modification treatment agent containing one type or a mixture of two or more types, and by bringing such a modification treatment agent into contact with fibrous asbestos and causing a reaction, this asbestos is made into agglomerates. This is a method for modifying asbestos by solidifying it.

The acid containing one or more elements of sulfur, nitrogen, or halogen used in the present invention is:
It refers to something that has any of these elements and exhibits properties as an acid in an aqueous solution state. Examples of acids containing sulfur include sulfur, sulfuric anhydride, fuming sulfuric acid, persulfuric acid, and sulfurous acid. Further, examples of acids containing nitrogen include nitric acid, fuming nitric acid, nitrous acid, etc. Furthermore, examples of acids containing halogen include hydrofluoric acid, hydrochloric acid, hydrobromic acid,
Hydroiodic acid, perfluoric acid, perchloric acid, perbromic acid, periodic acid, etc. can be mentioned. These acids can be used alone or as a mixture of two or more, and ammonium salts and metal salts of these acids can also be used in combination.

Note that the acid used in the present invention is suitable for asbestos containing MgO and
In the case of chrysotile (white asbestos), which has SiO ₂ as its main component, any of the acids mentioned above can be suitably used as its basicity is relatively strong, but this asbestos is not commonly used. Furthermore, although it is used only in extremely small quantities, if asbestos other than the above-mentioned chrysotile is used, such as amosite (brown asbestos) or crocidolite (blue asbestos), these may be SiO ₂ . Fe ₂ O ₃ is the main component, and its basicity is weak, so it reacts slowly with ordinary acids, and the modification may not proceed easily. Hydrogen acid, perfluoric acid or a mixture of a salt of a fluorine-containing acid and other acids is preferably used.

In addition, in the present invention, the aqueous inorganic polymer compound used together with the above acids has water solubility or water dispersibility, and has Si-O, Ti-O, Al-
It is a polymer compound that has at least one type of bond such as O, etc. When dissolved or dispersed in water, it is dissolved or dispersed in water as a polymer or dispersed in the form of a colloid, and when dried, it solidifies and forms itself. It has the ability to form a film. Examples of the water-soluble or water-dispersed liquid of this aqueous inorganic polymer compound include water glass, aqueous solution of alkyl silicate partial hydrolyzate, colloidal silica, aqueous solution of alkyl titanate partial hydrolyzate, titania sol,
Examples include alumina sol, which can be used alone or as a mixture of two or more.

In producing the modification treatment agent of the present invention, first, the aqueous solution of the aqueous inorganic polymer compound or water acidic liquid is added to the aqueous solution of the acid with stirring, and mixed thoroughly. At this time, the aqueous inorganic polymer compound may gel and precipitate.
It is necessary to stir sufficiently.

In the modifying treatment agent of the present invention, the concentration of acids is appropriately set such that the pH thereof is 3.5 or less, preferably in the range of 3.0 to 0.5, taking into account its reactivity. When the pH is lower than 0.5, it becomes difficult for an aqueous solution or aqueous dispersion of an aqueous inorganic polymer compound to exist stably, and gelation occurs and precipitates are likely to be formed. The concentration of the aqueous inorganic polymer compound is preferably about 0.5 to 20% by weight, preferably about 1 to 10% by weight as a solid content in the aqueous solution or dispersion of the modifying agent. If the amount used is less than 0.5% by weight, the ability to modify asbestos will be insufficient, and if it is more than 20% by weight, it may gel and precipitate in an aqueous solution or dispersion, which is not preferable.

In the present invention, in order to treat asbestos using a modification treatment agent, the modification treatment agent may be sprayed or applied directly onto the asbestos, or the modification treatment may be carried out while stirring and/or pulverizing the asbestos. At this time, in order to increase the reactivity of the modifying agent to asbestos, if necessary, the modifying agent and/or
Alternatively, the mixture can be heated to an appropriate temperature.

In addition, if the reaction between the modification treatment agent of the present invention and asbestos is completed and surplus acid remains, neutralize it using lime etc. Also, if acids containing nitrogen or halogen are used, Since reaction products with asbestos are often soluble in water, an appropriate amount of water-soluble or water-dispersible organic polymer compounds, such as polyacrylamide, polyvinyl butyral partial hydrolyzate, polyacrylic, is added to the modification treatment agent. It is also possible to add an emulsion or the like and form a water-insoluble film after drying for sealing.

Furthermore, this modification treatment agent can, in some cases, form a coating layer such as a spray layer on the surface of asbestos without disposing of it, and repair it in that state, or
It can be applied when carrying out containment processing.
Even in this case, the asbestos can be modified while being agglomerated by spraying or applying the modifying agent.

[Function] When asbestos is treated with the modifying treatment agent of the present invention, the acicular fibrous asbestos dissolves and solidifies into a lumpy substance. The reason for this can be considered as follows.

In other words, for example, if asbestos is chrysotile, the reason why it does not dissolve in ordinary acids even though it is basic and contains MgO/SiO ₂ as its main component is that its surface is difficult to dissolve in ordinary acids.
It is thought that this is because it is covered with a film whose main component is SiO ₂ .

However, when this asbestos is treated with the modifying agent of the present invention, which is an aqueous solution or aqueous dispersion containing the above-mentioned acids and an aqueous inorganic polymer compound, the inorganic polymer compound solidifies on the asbestos surface to form a film. Shrinkage stress occurs during this process. This shrinkage stress causes minute cracks in the film that is difficult to dissolve in normal acids that exists on the surface of asbestos, and active points are generated there, through which acids can enter and destroy the asbestos that exists inside the asbestos. It is thought that it reacts with basic MgO/SiO ₂ to form an acid salt of Mg.

[Example] Hereinafter, the present invention will be specifically described based on Examples.

Example 1 White asbestos (chrysotile) 40% by weight and cement 60%
The test piece was a product from which sprayed asbestos was removed, which contained % by weight.

A modification treatment agent having the following composition (weight % in terms of solid content) was prepared.

Sulfuric acid: 15 wt% Ammonium persulfate: 5 wt% Silica sol (as SiO2): 10 wt% This modification treatment agent was added to the above asbestos specimen at a weight ratio of 80%, and heated to 80°C. After stirring for 1 hour, it was dried and solidified.

When the components of the specimen after solidification were analyzed using X-ray diffraction, chrysotile was undetectable.
Instead, magnesium sulfate and silica, as well as trace amounts of calcium sulfate and iron sulfate were detected, and the acicular fibrous specimen had solidified into a lump.

Therefore, through this modification process, the acicular fibrous asbestos was modified into lumps, and its composition was also rendered harmless as described above, and it was found that it solidified in this state. did.

Example 2 A specimen was prepared from sprayed asbestos containing 40% by weight of brown asbestos (amosite) and 60% by weight of cement.

A modification treatment agent having the following composition (weight % in terms of solid content) was prepared.

Hydrofluoric acid...10wt% Nitric acid...5wt% Ethylsilicate partial hydrolyzate (as _SiO2 )...5wt% This modification treatment agent was added to the asbestos specimen above at a weight ratio of 70%. After heating to 70°C and stirring for 1 hour, the mixture was dried and solidified.

After solidification, 10% by weight of lime (solid content equivalent weight%) was added to the specimen to neutralize excess acid.
And 20% of 5wt% acrylic emulsion aqueous solution
% was added with stirring and dried and solidified. In this way, the fluoride was encapsulated in the form of calcium fluoride, and the nitrate was encapsulated in the acrylic emulsion, thereby modifying it into a poorly water-soluble substance.

The obtained treated product solidified into lumps, and as a result of analysis by X-ray diffraction method, amosite was undetectable, and calcium sulfate, calcium oxide,
Characteristic peaks of calcium fluoride, iron nitrate, iron fluoride, silica, etc. were observed.

[Effects of the Invention] According to the present invention, when asbestos-containing materials are disposed of as industrial waste, the acicular fibers are agglomerated and solidified without scattering, and the acicular fibers are It can be modified to make it harmless, and the practical effect is extremely significant.

Claims (1)

[Scope of Claims] 1. One or more mixtures of acids containing one or more elements of sulfur, nitrogen, or halogen, and one or more aqueous inorganic polymer compounds. An asbestos modification treatment agent characterized by containing a mixture thereof. 2. A treatment agent containing one or a mixture of two or more acids containing one or more elements of sulfur, nitrogen, or halogen, and one or a mixture of two or more aqueous inorganic polymer compounds. 1. A method for modifying asbestos, which comprises bringing the asbestos into contact with fibrous asbestos and reacting with the asbestos, thereby clumping and solidifying the asbestos.