JP2009214078A - Process for detoxifying asbestos, and soil conditioner obtained by the process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for detoxifying asbestos using an easily available material and further capable of reusing the processed asbestos as a soil conditioner, and the soil conditioner obtained by the process. <P>SOLUTION: Asbestos and an acid treating agent are put into a mixer and mixed for about two hours. In the next place, the asbestos treated with the acid is taken out from the mixer, and put into a mixer other than the mixer used for the first treatment. Then, calcium oxide and water are added to the asbestos and the mixture is kneaded. Chrysotile changes to calcium silicate and the like owing to a chemical reaction of asbestos with unslaked lime and oxygen, and a high temperature treatment with a heat generated by adding water to unslaked lime. Then, adding water and kneading are finished when the kneaded material of the asbestos, the unslaked lime, and the water becomes a solid bunched up completely together. Thereafter, the solid is taken out from the mixer, cooled, and pulverized into granules to be the soil conditioner. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention has been widely used for heat insulation of buildings in the past, but asbestos detoxification to detoxify asbestos, whose use is currently prohibited due to danger to the human body, and its treatment has become a major problem The present invention relates to a treatment method and a soil conditioner by the treatment method.

Asbestos is a kind of natural mineral fiber consisting of very fine needle-like crystals. It has excellent durability, heat resistance, chemical resistance, etc., and it is inexpensive, so it is a construction material and electrical product as a “miracle mineral”. It has been widely used in automobiles, household goods, etc. However, when asbestos scatters into the air and enters the human lungs, fine needle-like crystals pierce the lungs, causing lung cancer, malignant mesothelioma, and pulmonary fibrosis after decades of incubation. . Therefore, it is currently prohibited to use it as a substance that causes serious health damage to the human body, and its existence and treatment are a major social problem. Then, there exists an asbestos scattering prevention construction method which prevents asbestos from scattering by impregnating asbestos with water and spraying a lime powdery body after that (patent document 1). In addition, asbestos treatment methods include an asbestos dissolution treatment method in which asbestos is heated and melted at a high temperature of 1500 to 2000 degrees in a melting furnace, and then the melted asbestos is solidified and buried as waste (patent) Reference 2).
Japanese Patent No. 3787350 JP 2007-319838 A

  However, the asbestos scattering prevention method described above only prevents asbestos from being scattered in the air, and since a large amount of asbestos remains, it is difficult to say that the risk of asbestos has been eliminated. In addition, since the asbestos melting treatment method described above involves heating and melting asbestos at a high temperature, a melting furnace that can withstand high temperatures is required on a large scale, and it requires initial costs such as installation of the melting furnace, and heat treatment. There is a problem that the fuel cost for doing so increases. Furthermore, since the melted asbestos is solidified and buried, it is necessary to secure land as a buried treatment site for burying a large amount of asbestos waste, and the cost of managing the buried treatment site is high. There is also.

  The present invention has been made in view of the above-mentioned disadvantages of the prior art. Asbestos is reliably rendered harmless by using a material that can be easily obtained without using a large apparatus, and further, asbestos after processing. An object of the present invention is to provide an asbestos detoxification treatment method that can be reused as a soil conditioner and a soil conditioner by the treatment method.

The means of this invention comprised in order to solve the subject mentioned above is a 1st process process which mixes an asbestos or an asbestos containing material with the acid treatment agent which consists of plant-type vinegar , and acid-processes, and this 1st process process. It comprises a second treatment step in which acid-treated asbestos or asbestos-containing material is reacted with water and quicklime to produce a solidified product containing calcium silicate or the like.

  The first processing step and the second processing step may be performed using a transportable concrete mixer.

  Furthermore, the solidified product containing calcium silicate or the like may be crushed into granules and used as a soil conditioner.

Moreover, the means which comprises this invention which concerns on Claim 4 mixes an asbestos or asbestos containing material with the acid treatment agent which consists of a plant-type vinegar , and acid-processes, Furthermore, this acid-treated asbestos or asbestos containing material is water. And to be produced by kneading with quicklime.

The present invention has the following effects by adopting the above-described configuration.
(1) Asbestos is acid-treated as a first treatment to degrade needle-like crystals, and as a second treatment, it is changed to calcium silicate or the like by a chemical reaction with quick lime and heat treatment generated by mixing water and quick lime. At the same time, it can be solidified to make asbestos harmless.
(2) Since the asbestos is heat-treated using the heat generated by the reaction between water and quicklime, it is not necessary to perform a combustion process using a large amount of fuel, and the processing cost can be reduced. Since there is no generation of carbon dioxide, the environment is not adversely affected.
(3) Any processing agent that is expensive and requires special handling in handling by using plant vinegar such as quick lime, fir vinegar, wood vinegar, bamboo vinegar, etc. Since it does not need to be used, asbestos treatment can be performed at low cost and the safety of work can be improved.
(4) By using a transportable concrete mixer, it is possible to carry the asbestos treatment directly on-site, so there is no need to transport the pre-treatment asbestos to the treatment plant. In addition, the processing cost can be reduced, and the risk of asbestos scattering during transportation can be avoided.
(5) Since asbestos is kneaded with quicklime to change to a solidified product mainly composed of calcium silicate, it can be effectively used as a soil conditioner without discarding the detoxified asbestos. .
(6) Since the solidified material can be effectively used as a soil conditioner without being discarded, it is economical because it is not necessary to secure land and facilities for disposal.
(7) Since the acid treatment agent is not a chemical, but a plant-derived liquid selected from rice vinegar, wood vinegar, bamboo vinegar, etc., safe soil improvement that does not harm asbestos to the human body It can be made into an agent.

Hereinafter, an embodiment of the present invention will be described with reference to the flowchart of FIG. First, asbestos removed from a building or the like and an acid treatment agent are put into a mixer (step 1). In this embodiment, a general concrete mixer truck is used as a mixer. However, the present invention is not limited to a concrete mixer truck, and various concrete mixers can be used, and the size of the mixer may be appropriately selected according to the amount of asbestos to be processed. By using a concrete mixer that can be carried in, the mixer can be carried directly into the site where asbestos is present, and asbestos treatment can be carried out on the spot. Rapid processing is possible. Moreover, there is no danger of scattering by carrying asbestos before a long distance. However, since the metal portion may be significantly corroded by the acid treatment agent, it is desirable to perform resin processing for coating the metal portion of the mixer with a resin in order to prevent corrosion.

  As the acid treatment agent, any of plant vinegars such as fir vinegar, wood vinegar, and bamboo vinegar is used. These are strongly acidic liquids having a pH of around 3.0 that can acid-treat asbestos, and all are plant-derived liquids. The acid treatment agent is preferably used in an amount of about 3 times the volume of asbestos. This is an amount obtained by experiment, and by using about three times the amount, the asbestos needle crystal can be softened and deteriorated more reliably.

  And asbestos and an acid treatment agent are mixed with a mixer (step 2). In order to ensure acid treatment of asbestos, it is desirable to have a mixing time of about 2 hours. By mixing and acid-treating asbestos, acicular crystals of asbestos can be dissolved and softened and deteriorated. Further, asbestos is often removed from buildings as spraying material waste in a state of being mixed with cement or the like, and has an effect of dissolving and removing cement or the like adhering to asbestos by acid treatment. Next, the acid-treated asbestos is taken out from the mixer and separated from the acid treatment agent (step 3). In addition, when taking out from a mixer, it is good to isolate | separate asbestos and an acid treatment agent reliably by taking out asbestos so that it may crawl using a net | network. Since the acid treatment agent thus separated from asbestos can be used multiple times for different asbestos treatments, the acid treatment agent is not wasted. However, when the acid treatment agent is used repeatedly, foaming that occurs when mixed with asbestos gradually decreases. This is because acetic acid is gradually neutralized with lime adhering to asbestos. Therefore, it is preferable to replace with a new acid treatment agent when the amount of foaming is about half of the initial level. When discarding the used acid treatment agent, only the supernatant of the acid treatment agent is discarded, and the precipitate is not discarded in addition to asbestos.

Next, the acid-treated asbestos is put into a mixer different from the mixer used in the first treatment (step 4). The mixer uses a general concrete mixer that can be transported in the same manner as in Step 1. In addition, it is quick lime to mix with asbestos in step 5 mentioned later, and since there is no possibility that corrosion will occur, it is not necessary to resin-process a mixer. And quicklime is added to asbestos (step 5). It is recommended that quick lime be added in an amount of about 3 times the volume of asbestos.

After adding quicklime, asbestos and quicklime are kneaded with a mixer while adding water little by little (step 6). Water is preferably added in small amounts of about 1/4 to 1/2 times the volume of asbestos. Since tap water or river water can be used as water, asbestos treatment can be performed at low cost. In addition, when water is added to quicklime, it generates heat intensely, so put a rubber cap on the opening of the mixer in advance, open two holes in the cap, and one is for water use to insert a hose, If the other one is for steam removal, work safety can be secured.

When asbestos and quicklime are kneaded, they gradually solidify and absorb oxygen in the air to cause a chemical reaction. Moreover, when water is added little by little to quick lime, the quick lime changes to slaked lime, and at the same time, a strong heat generation of about 100 degrees or more occurs, and the asbestos is treated at a high temperature by the heat. Since the acicular crystals of chrysotile are deteriorated and softened by the acid treatment in Step 2, chrysotile [Mg ₆ Si ₄ O ₁₀ (OH) ₈ ] and quick lime [as the main components of asbestos] are obtained by this chemical reaction and high-temperature treatment. CaO] and oxygen [O ₂ ] are harmless to human body into calcium silicate [CaSiO ₄ ], magnesium silicate [MgSiO ₄ ], magnesium hydroxide [Mg (OH) ₂ ], and slaked lime [Ca (OH) ₂ ] Change. In this way, asbestos can be reliably rendered harmless. Then, when the asbestos, quicklime and water kneaded product becomes a dumpling-like solidified product, hydration and kneading are finished. In this way, the present invention pays attention to the fact that asbestos is composed of fine acicular crystals and has a very large surface area, and thus has high reactivity. By performing acid treatment, high temperature treatment, and reaction treatment with quicklime, fine acicular shapes are obtained. Asbestos is detoxified by rounding the tip so that the crystal does not pierce the cells and degrading it, and then changing it to a substance that is not harmful to the human body.

After completion of the kneading operation, the solidified product is taken out from the mixer and cooled (step 7). Then, the cooled solidified product is crushed into fine particles (step 8). The solidified product produced by kneading with quicklime and water is not toxic and is mainly composed of calcium silicate, magnesium silicate, magnesium hydroxide and slaked lime that do not adversely affect the human body. By spraying, it can be effectively reused as a soil conditioner that improves acidic soil to weak acidity. Moreover, if it sprays on the volcanic ash soil etc. which contain many active aluminum which makes a soil acidic, it can utilize effectively also as a soil improvement agent which corrects active aluminum by the chemical reaction shown below.
Al ³ + OH ⁻ → Al (OH) ₃
The acid treatment agent used for acid treatment of asbestos is vinegar liquid, wood vinegar liquid, bamboo vinegar liquid, etc. which are plant-derived liquids that are not harmful to the human body, so the soil conditioner is used with peace of mind as being harmless to the human body can do. The solidified product becomes hard and hard to be crushed when it is completely cooled. Therefore, it is desirable that the pulverization is performed after the heat has been lowered to some extent and before it is completely cooled.

As a result of inspecting the solidified material produced by kneading with a polarizing microscope, it was confirmed that the residual rate of the asbestos needle crystals after the treatment can be reduced to about 2% or less by performing the detoxification treatment according to the present invention. did. And the slightly remaining needle-like crystals of about 2% or less are also kneaded with quick lime so that they do not scatter and are fixed to quick lime, and the change to calcium silicate and the like due to a chemical reaction is continuously continued. As a result, the asbestos needle crystal completely disappears, and asbestos can be completely detoxified.

Table 1 shows the analysis result of the content of the solidified product produced by the detoxification treatment method according to the present invention. The analysis was performed using an alkali melting method, and the solidified product was treated with hot hydrochloric acid, and then analyzed for silicic acid and the like by alkali dissolution. In addition, it is the custom of chemical analysis that the analysis item is shown in the acid form, and it does not mean that the contained component is in the acid form. As shown in the table, the solidified product after the treatment is mainly composed of silicon dioxide and calcium oxide, and it can be seen that asbestos harmful to the human body is reliably detoxified.

It is a flowchart which shows the process process of the asbestos detoxification processing method.

Claims (5)

  A first treatment step in which asbestos or an asbestos-containing material is mixed with an acid treatment agent for acid treatment, and the asbestos or asbestos-containing material acid-treated in the first treatment step is reacted with water and quicklime to react with silicic acid. An asbestos detoxification treatment method comprising a second treatment step produced in a solidified product containing calcium or the like.   The asbestos detoxification method according to claim 1, wherein the acid treatment agent is a plant vinegar solution such as a rice vinegar solution, a wood vinegar solution, or a bamboo vinegar solution.   The asbestos detoxification method according to claim 1 or 2, wherein the first treatment step and the second treatment step are performed using a transportable concrete mixer.   The asbestos detoxification method according to any one of claims 1 to 3, wherein the solidified product containing calcium silicate or the like is crushed into granules to form a soil conditioner.   An asbestos or an asbestos-containing material mixed with an acid treatment agent, acid-treated, and further, the asbestos produced by mixing the acid-treated asbestos or asbestos-containing material with water and quicklime is rendered harmless.

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