JP2007295943A - Method of detoxification by dissolving asbestos - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the adverse effect of asbestos crystals on a living body by dissolving asbestos with the chemical reaction of phosphoric acid selected as a practical treatment chemical, which is harmless to the living body, without burden on the global environment, inexpensive and easily handlable, among chemicals capable of dissolving asbestos. <P>SOLUTION: Asbestos reacts to the plain phosphoric acid solution, but loses the fluidity because the viscosity of the reaction product is high if the concentration is high. As a result, the dissolution reaction at the center is prevented, which causes the unevenness of the unreacted substance (lumps). If the concentration is excessively low, the overall reaction declines. In this way, it is important to set the concentration according to the state of the asbestos (whether air-borne asbestos or mixed with cement, etc.), and specifically, addition of a specific quantity of hydrogen peroxide solution is the most effective to prevent the unevenness in the reaction and to prevent the malodor generated at the time of reaction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

Detailed Description of the Invention

  The present invention relates to a treatment method for detoxifying mainly asbestos crystals by a chemical reaction of phosphoric acid.

  Due to the harmfulness of asbestos used in buildings, etc., the handling method to prevent this is a wetting method by spraying water. For final disposal, bury it in the soil with the straw in a vinyl bag. A method of hardening with concrete. A method of melting in a high temperature furnace. The method of containment with the current bag. Enclosure method is performed.

Problems to be solved by the invention

  As a method for handling and treating asbestos that is harmful to living organisms, conventional methods are too dangerous. In order to fundamentally detoxify asbestos, the crystal structure must be deformed (in a spherical shape) to be melted away.

Means to solve the problem

Phosphoric acid reacts with the metal ion portion of the asbestos molecule to dissolve the asbestos into a phosphate. In the first stage, alkaline earth Ca, Mg, etc. in the asbestos molecule are transparently dissolved as the first phosphate, and the reaction proceeds sequentially, and the pH value increases from the acidity of phosphoric acid to a weakly alkaline level, so A di-salt (MHPO ₄ ) to a tertiary salt (M ₃ (PO ₄ ) ₂ ) are produced and converted to crystals that are safe for the living body, different from asbestos.

  The optimum conditions for asbestos treatment with a phosphoric acid solution vary depending on the object of the treatment.

  First, when a high concentration phosphoric acid solution is applied to the asbestos layer (sprayed) on the steel frame or wall surface with an adhesive or the like for the purpose of heat insulation, the thickness is about 20 mm or more. As a result, asbestos on the surface reacts violently and partially dissolves, and the periphery (surface) is covered with a high concentration of reaction product, resulting in a high viscosity. As the process progresses, the periphery begins to harden, and the back part is not dissolved compared to the surface layer part.

On the other hand, for the purpose of reducing the viscosity (concentration) of phosphoric acid, if water is added excessively, the original reactivity is lowered, and various test results show that aqueous solutions with a phosphoric acid concentration in the range of 30-50% (commercially available 75-85% Dilute phosphoric acid solution with water) is suitable for use.

However, the treatment with the phosphoric acid solution alone has the following problems.
(A) Odor is generated when asbestos dissolves in the phosphoric acid solution.
(B) In the dissolution reaction with a simple phosphoric acid solution, lumps (unevenness) are likely to occur in the dissolved asbestos.

These problems can be improved by adding hydrogen peroxide water.
When hydrogen peroxide water is added, the odor generated during the reaction with asbestos is reduced, and the amount of asbestos dissolved is increased.

  Further, by adding hydrogen peroxide solution, the solubility of asbestos is averaged, and it is fine and uniform, and a clean dissolution result can be obtained.

  Asbestos sprayed on a steel frame or a wall surface for the purpose of preventing heat or the like contains approximately 3 to 5% hydrogen peroxide in a phosphoric acid solution. Aerial spraying of higher concentrations is harmful to workers.

  In the treatment of item 0006 (thickly sprayed on a steel frame, etc., for an asbestos layer of about 20 mm or more), an aqueous solution having a phosphoric acid concentration of about 30 to 35 ± 5% is used for the first application. Apply a relatively light brush or spray (especially with the spray squeezed finely), moisten the surface layer of asbestos and suppress the asbestos scattering, By gently spraying a 50% ± 10% aqueous solution of phosphoric acid for the second time in a state where the spray is often roughened, a treatment result that is slightly rougher than the treatment result of the next item 0013 is obtained.

  Further, for the first coating of item 0006, a solution diluted with water to a phosphoric acid concentration of about 30 to 35% ± 5% and a hydrogen peroxide content of 3 to 5% is applied to a brush or spray (especially a spray). Apply a relatively light (thin) coating by squeezing and spraying finely, and wet the surface layer of asbestos to suppress the scattering of asbestos, then the second coating solution (about 50 ± 5% When the spray is carefully sprayed with a phosphoric acid concentration and a 3-5% aqueous solution), the asbestos dissolves cleanly.

  The asbestos residue dissolved and decomposed in the phosphoric acid solution immediately precipitates as another crystal body (regular hexahedron having a grain size of about 100 to 300 microns). From these, plaster and mortar to gypsum mortar Etc., it becomes a white cured product in several tens of hours.

  When asbestos waste is dissolved with the phosphoric acid solution filled in a tank or the like, an aqueous solution containing a phosphoric acid content of 50 ± 10% and a hydrogen peroxide content of up to 15% is suitable. In actual melting work, it is important to stir well.

The invention's effect

  The present invention is implemented in an easy processing mode as described above, and has the following effects.

Phosphoric acid solution dissolves crystals (micro-cylindrical shape) that are considered asbestos-risk, but if the concentration is too high, the viscosity of the reaction product is high, so the solution adheres when the asbestos layer is thick. Only the part reacts and the reaction cannot diffuse throughout due to the high viscosity product, and the periphery, especially the lower part of the layer, often ends up unreacted. It cannot be completed completely, and a large amount of reaction solution is required, so that the surrounding area is immersed in water.
The 30-50% aqueous solution is suitable for asbestos treatment.

  When hydrogen peroxide is added to the phosphoric acid solution, its action is further increased, and there is an effect of dissolving asbestos densely.

  Hydrogen peroxide added to the treatment liquid has an effect of suppressing odor generated when asbestos dissolves in phosphoric acid.

  This method can be detoxified simply by applying it to asbestos, and the exfoliated material can be dissolved by simply filling the tank with a solution, and can be applied widely and give good results.

Claims (8)

Phosphoric acid concentration that prevents the scattering of asbestos by wetting, which is the purpose of the first (first stage) treatment of sprayed asbestos (others, asbestos-containing spray lock wool, asbestos-containing fireproof clothing board, etc.) and slow dissolution 30-35 ± 5% first treated (water) solution. And other compositions for slow dissolution of asbestos building materials. Contrary to claim 1, an aqueous solution having a phosphoric acid concentration of 50 ± 5% as a second-stage treatment liquid in the latter stage, which is a rapid dissolution exclusive liquid. And liquid composition for rapid dissolution of asbestos building materials. Asbestos in the form of a spray in which the first-stage treatment liquid (the treatment liquid of claim 1) is finely squeezed as a pre-stage of detoxification treatment of sprayed asbestos (asbestos-containing spray rock wall, asbestos-containing fireproof clothing board, etc.) Gently spray onto the surface to suppress the asbestos scattering while giving wetness, and when the whole is wet, the second stage treatment liquid (the treatment liquid of claim 2) is now coarsened. , A method to dissolve and detoxify asbestos by thoroughly spraying it on the asbestos surface. A composition of a treatment liquid in which the reactivity is improved by adding 3 to 5% of hydrogen peroxide to the same aqueous solution as in claim 1 having a phosphoric acid concentration of 30 ±%. A composition of a treatment liquid having improved reactivity by adding a hydrogen peroxide content of 3 to 5% to the same solution as in claim 2 having a phosphoric acid concentration of 50 ± 5%. Composition of phosphoric acid solution for dissolving asbestos for dissolution tank (tank) (aqueous solution of phosphoric acid 50 ± 10%, hydrogen peroxide content about 10%). A method for continuously dissolving and treating asbestos while putting the asbestos solution of claim 6 into a dissolving layer (tank), adding asbestos waste, etc., and stirring gently with a stirrer. The method of applying the stucco, mortar, or gypsum mortar to harden the residue of the dissolved asbestos after the treatment according to claim 1 and claim 2 without intentionally peeling it.