JP2008272592A - Asbestos processing method and processing apparatus for composite material containing asbestos - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating asbestos of a composite containing asbestos and the like capable of efficiently decomposing (defiberizing) fibrous asbestos by scattering no fibrous asbestos, specially in a highly reinforced composite containing asbestos such as slate materials that are disposed of. <P>SOLUTION: After the composite containing asbestos containing the fibrous asbestos and cement is immersed in a preliminary reaction liquid containing sodium chloride or both sodium chloride and calcium chloride to impregnate the preliminary reaction liquid in the composite, a mechanical strength of the composite is deteriorated by heating the same at a temperature of 560 to 700°C and is crushed into grains. Then, the crushed composite is immersed in a main reaction liquid containing calcium chloride or both calcium chloride and sodium chloride to impregnate the main reaction liquid in the composite; thereafter, chemical bonds of Mg and Si in the asbestos compounds are cut by heating the composite at a temperature of 710 to 960°C to decompose (defiberize) the fibrous asbestos. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an asbestos treatment method and treatment apparatus for an asbestos-containing composite material, and in particular, after making a high-strength asbestos-containing composite material, such as a slate material reinforced with fibrous asbestos or a water pipe, easily crushed, The present invention relates to an asbestos detoxification technology that can effectively make non-fibrous asbestos.

    Sbestos is a naturally occurring mineral fiber. Industrial products that use asbestos range from slate materials, water pipes, fireproof coating materials, brake pads, gaskets, heat insulation plates, ropes, packing, and acetylene cylinder fillers. Of these, the slate material has a particularly large amount of use. In order to reinforce the strength of the cement, about 15 to 20% by mass of asbestos is mixed. Slate materials have been used in large quantities such as ceilings and wall materials. Water pipes are also used in large quantities.

  Since the slate waste material which is the discarded slate material is stable, it is handled as general waste. However, if the cement hardened material is neutralized, it is predicted that asbestos will be scattered and released. Therefore, there are no special measures at present.

  In addition, the dismantling of buildings using asbestos-containing building materials such as fireproof coverings and collapsed ceiling panels will peak in the future, and asbestos exposure and asbestos treatment problems will become serious. Building materials after disposal are tightly sealed and become specially controlled substances, and their cost facilities are enormous. The slate material is a stable and highly fire-resistant material in which asbestos is hardened with cement, and higher energy is required to decompose, melt, and collapse the waste material.

  Asbestos, a slate reinforcement, causes many health problems such as asbestosis, lung cancer, and malignant mesothelioma. However, because of its long incubation period and high disease rate, it was said to be a bad substance and its use was prohibited. The harmfulness of asbestos originates from the fiber, and it is considered that the modification and melting of the fiber are the points of detoxification.

    The present inventors have developed a method for melting and detoxifying asbestos by heating it to 575 ° C. together with a fluorocarbon decomposition product mainly composed of calcium fluoride. However, asbestos in the slate waste material could not be decomposed by this method. Therefore, if the asbestos in the slate waste material could be melted, it was thought that many other materials using asbestos could be made harmless.

In general, the decomposition of asbestos contained in slate wastes usually requires a high temperature of about 1500 ° C. There is no known technique for melting and vitrifying asbestos in slate waste having excellent heat resistance at a low temperature of 1000 ° C. or lower. The present inventors proposed in Patent Document 1 a method in which borosilicate glass is formed from a slate plate and decomposed at 800 to 850 ° C. to melt the slate. However, the method described in Patent Document 1 has problems such as that it takes time to melt a slate plate having a certain thickness and that the added chemical is expensive.
JP 2005-279589 A

As a means for decomposing and detoxifying asbestos, for example, a closed electric furnace melting method described in Patent Document 2 and a slag bath melting method described in Patent Document 3 can be cited. It has not been put into practical use because it requires temperature and has enormous energy consumption problems. There are also attempts to melt with high temperature plasma, but no attempt has been made.
Japanese Patent No. 3085959 Japanese Patent Laid-Open No. 7-171536

Further, the present inventor immerses the spray material containing fibrous asbestos and a calcium oxide component in a reaction solution containing calcium chloride and impregnates the reaction solution in the composite material, and then 600 to 800 ° C. Patent application title: Asbestos detoxification method for composite material containing asbestos, which breaks the chemical bond between Mg and Si in the asbestos compound and decomposes the fibrous asbestos into granules or powders 4 proposed.
Japanese Patent No. 3747246

  In the method described in Patent Document 4, a composite material containing fibrous asbestos is decomposed into granular or powder form by heating the reaction liquid containing the specific compound at a low temperature to decompose the asbestos into granular or powder form. It is a detoxifying method, and it is effective in the case of a low-strength composite material that can be easily impregnated with a reaction liquid without being crushed, such as the spray material, but it has a strength similar to that of a slate material or water pipe. In the case of a high-strength composite material that is difficult to impregnate the reaction liquid into the composite material as it is, the reaction liquid is sufficient for asbestos in the slate material unless the reaction liquid is impregnated after the composite material is crushed. In some cases, fibrous asbestos could not be effectively decomposed.

  By the way, the slate material containing asbestos is plate-shaped, the water pipe is cylindrical, and the fireproof covering material is hard cotton. In order to decompose or melt a shape, it is advantageous to make the shape as small as possible. For this purpose, a pulverization process, a decomposition process, a microcrack generation process, and the like are required as pretreatment. They also have mechanical methods and may be destroyed using heavy machinery or the like, but it is not preferable because asbestos is scattered. Therefore, it is desirable to process in the form used as building materials etc. as much as possible, or in the form crushed at the minimum.

  The object of the present invention is to provide an asbestos-containing composite material containing fibrous asbestos and cement, in particular, an asbestos-containing high-strength composite material such as a slate material or a water pipe, without scattering the fibrous asbestos. An object of the present invention is to provide an asbestos treatment method and apparatus for an asbestos-containing composite material capable of effectively decomposing (non-fibrosis) asbestos.

In order to achieve the above object, the gist of the present invention is as follows.
(1) Asbestos-containing composite material containing fibrous asbestos and cement is heated to 710 to 960 ° C. to reduce the mechanical strength of the composite material, and then the composite material is crushed into granules, and then chlorinated. The main reaction solution is immersed in the main reaction solution containing calcium or both calcium chloride and sodium chloride, and then impregnated in the composite material, and then heated at a temperature of 710 to 960 ° C. and Mg in the asbestos compound An asbestos treatment method for an asbestos-containing composite material, characterized by breaking a chemical bond of Si and decomposing fibrous asbestos (first invention).

(2) An asbestos-containing composite material containing fibrous asbestos and cement was immersed in a pre-reaction solution containing sodium chloride or both sodium chloride and calcium chloride, and the pre-reaction solution was impregnated in the composite material. Then, the main reaction containing calcium chloride or both calcium chloride and sodium chloride is performed by reducing the mechanical strength of the composite material by heating at a temperature of 560 to 700 ° C. The composite is immersed in the liquid so that the main reaction liquid is impregnated, and then heated at a temperature of 710 to 960 ° C. to break the chemical bond between Mg and Si in the asbestos compound and decompose fibrous asbestos. An asbestos treatment method for an asbestos-containing composite material (second invention).

(3) An asbestos-containing composite material containing fibrous asbestos and cement is immersed in a main reaction solution containing both sodium chloride and calcium chloride so that the main reaction solution is impregnated in the composite material, and then 710 An asbestos treatment method for an asbestos-containing composite material, which is heated at a temperature of ˜960 ° C. to break chemical bonds between Mg and Si in the asbestos compound and decompose fibrous asbestos (third invention).

(4) The asbestos treatment method for an asbestos-containing composite material according to (1), (2), or (3), wherein the composite material is an asbestos-containing high-strength composite material such as a slate material or a water pipe.

(5) The asbestos treatment method for an asbestos-containing composite material according to any one of (1) to (4), wherein the main reaction solution further contains an auxiliary additive compound that forms a molten salt in calcium chloride at a low temperature.

(6) A main material in which the asbestos-containing composite material containing fibrous asbestos and cement is immersed in a main reaction solution containing calcium chloride or both calcium chloride and sodium chloride so that the main reaction solution is impregnated in the composite material. The chemical bond between Mg and Si of the asbestos compound in the composite material is cut by heating the impregnation means and the composite material impregnated with the main reaction solution by the main impregnation means at a temperature of 710 to 960 ° C. An asbestos treatment apparatus for an asbestos-containing composite material, comprising: main heating means for decomposing fibrous asbestos into a granular or powder form.

(7) The above (6) further comprising embrittlement means for reducing the mechanical strength of the asbestos-containing composite material, and crushing means for crushing the composite material whose mechanical strength has been reduced by the embrittlement means into granules. The asbestos processing apparatus of the asbestos containing composite material of description.

(8) The asbestos treatment apparatus for asbestos-containing composite material according to (7), wherein the embrittlement means is preheating means for heating the asbestos-containing composite material at a temperature of 710 to 960 ° C.

(9) The embrittlement means heats the composite material impregnated with the preliminary reaction solution immersed in sodium chloride or both sodium chloride and calcium chloride at a temperature of 560 to 700 ° C. The asbestos treatment apparatus for an asbestos-containing composite material according to (7), which is a pre-impregnation heating means.

  According to the present invention, an asbestos-containing composite material containing fibrous asbestos and cement, in particular, an asbestos-containing high-strength composite material such as a slate material or a water pipe to be discarded, without scattering the fibrous asbestos. It has become possible to provide an asbestos treatment method for an asbestos-containing composite material that can effectively decompose (non-fibrous) asbestos.

Next, an embodiment according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a typical embodiment of an asbestos treatment apparatus suitable for use in the asbestos treatment method for an asbestos-containing composite material according to the first invention.

  The asbestos treatment apparatus 1A in FIG. 1 is mainly composed of a main impregnation means 2 and a main heating means 3.

  The main impregnation means 2 immerses an asbestos-containing composite material C containing fibrous asbestos and cement in a main reaction solution L1 containing calcium chloride or both calcium chloride and sodium chloride, and the main reaction solution L1 is mixed with the composite material C1. For example, the first reaction tank 4 to which the main reaction liquid L1 is supplied is provided for impregnation in the material. In order to accelerate the impregnation effect, it is desirable to have a heating device and a deaeration device.

  For mixing these liquids, as shown in FIG. 3, a plurality of types of tanks, that is, a sodium chloride aqueous solution tank 5, a water tank 6, a sodium chloride and calcium chloride mixed aqueous solution tank 7 and a calcium chloride aqueous solution are used. A tank 8 or the like is provided, and the amount of each solution from these tanks 5 to 8 is supplied to the first reaction tank 4 by adjusting the valve 9 to open and close the main reaction liquid L1 having a desired composition and volume. Can do. FIG. 1 shows a case where a plurality of sprays 21 are arranged above the first reaction tank 4 in order to supply the main reaction liquid L1, but sprays are arranged as shown in FIG. The main reaction liquid L1 can be directly supplied to the 1st reaction tank 4 through piping by adjusting opening and closing of the valve | bulb 9 without installing.

  The main heating means 3 heats the composite material C impregnated with the main reaction liquid L1 by the main impregnation means 2 at a temperature of 710 to 960 ° C., whereby Mg and Si of asbestos compounds in the composite material are heated. It is provided to break chemical bonds and decompose fibrous asbestos into granules or powders. Examples include box, rotary furnace, vertical type, horizontal type, stalker furnace, etc. Wood, etc. can be used. Furthermore, in order to enhance the mixing effect during heating, it is preferable to equip a rotary kiln, a rotating shaft having a stirring function, or a screw shaft.

  As the main heating means 3, for example, it has a stirring and mixing mechanism that uniformly generates a reaction between the composite material C and calcium chloride, and can be heated to a predetermined temperature so that undecomposed asbestos does not flow out of the apparatus. An example of the heat treatment furnace 10 is a negative pressure state. The heating temperature is 710 to 960 ° C. If it is less than 710 ° C., asbestos is not easily decomposed, and is preferably 750 ° C. or higher, more preferably 800 ° C. or higher. The upper limit of the heating temperature is 960 ° C. or less, preferably 850 ° C. or less from the viewpoint of energy cost.

  Further, the main heating means 3 has a configuration in which the composite material C is gradually moved by rotating the screw 11 or the shaft in the heat treatment furnace 10 as shown in FIGS. 1 and 2, that is, the screw 11. Alternatively, the rotational speed of the shaft may be adjusted, or as shown in FIG. 4, the composite material C may be moved on the belt conveyor 12, and the asbestos Mg and Si in the composite material C may be moved. It is preferable to allow the composite material C to stay in the heat treatment furnace 10 for a period of time longer than the time when the chemical bond can be sufficiently broken and the fibrous asbestos can be sufficiently decomposed into granular or powdery form, preferably 10 minutes to 2 hours. .

  Although not shown in detail in FIG. 1, the composite material inlet 13a in the heat treatment furnace 10 has a plurality of components in order to prevent a temperature drop in the heat treatment furnace 10, scattering of fibrous asbestos, and external leakage of the generated gas. It is preferable to form the on-off valve structure. Furthermore, as shown in FIG. 4, when using the belt conveyor 12 as a moving means, it is preferable to form the discharge port 13b of the heat treatment furnace 10 with a plurality of on-off valve structures as well as the loading port 13a. In addition, the atmosphere in the heat treatment furnace 10 is preferably reduced (negative pressure) in order to prevent asbestos from flowing out of the apparatus.

  The asbestos treatment apparatus 1A of the present invention is mainly composed of the main impregnation means 2 and the main heating means 3 described above. Prior to applying the main impregnation means 2, the mechanical strength of the asbestos-containing composite material C is as follows. It is preferable to further include an embrittlement means 14 for reducing the strength and a crushing means 15 for crushing the composite material C whose mechanical strength has been lowered by the embrittlement means 14 into a granular shape. By applying the main impregnation means 2 after crushing the composite material C into granules, the main reaction liquid can be sufficiently impregnated (contacted) with the fibrous asbestos in the composite material. This is because the impregnation means 2 facilitates the decomposition (non-fibrosis) of the fibrous asbestos.

  As the embrittlement means 14, for example, as shown in FIG. 1, a preheating means, for example, a heat treatment furnace 16 having the same configuration as the heat treatment furnace 10 used in the main heating means 3, The moving speed can be constituted by the belt conveyor 17 or the like so that it can stay in the heat treatment furnace 16 for longer than the time when the mechanical strength is sufficiently lowered, preferably 10 minutes to 2 hours.

  The crushing means 15 is an apparatus for crushing the asbestos-containing composite material C whose mechanical strength has been lowered by the embrittlement means 14, for example, a rotary kiln having a function of mixing, grinding, a screw kiln, a ball mill, Examples thereof include a rod mill and other equipment having a grinding function. There are various pulverization and crushing methods. Any method can be used as long as the composite material can be crushed and granulated.

  In FIG. 1, the crushing device 15 has a crushing section 20 composed of a rotating shaft 18 extending in the horizontal direction and a plurality of rotating blades 19 attached to the rotating shaft 18 at a predetermined interval. The diameter of the composite material is reduced by rotating the rotating shaft 18 of the crushing portion 20 at a predetermined number of rotations by driving means such as a motor M. Further, FIG. 1 shows a case where a plurality of nozzles 21 for spraying water are arranged on the upper surface of the crushing device 15 in order to prevent the composite material from scattering due to crushing. In the case of a sealed structure that can prevent the material from scattering due to crushing, the arrangement of the nozzles can be omitted as shown in FIG. The nozzle 21 of the crushing device 15 is replaced with water by an aqueous solution containing calcium chloride or a mixed aqueous solution containing both sodium chloride and calcium chloride prior to the process of impregnating the composite material with the main impregnation means 2. A certain main reaction liquid can be sprayed for further impregnation, and a liquid to be sprayed by the nozzle 21 may be selected as necessary.

  FIG. 3 shows an asbestos treatment apparatus 1B suitable for use in the asbestos treatment method according to the second invention. This apparatus 1B is configured to apply the embrittlement means 14 to the preheating means 14a. The composite material C is immersed in the pre-reaction liquid L2 containing sodium chloride and subjected to pre-impregnation means 14b for impregnating the pre-reaction liquid L2 into the composite material C. This is a pre-impregnation heating means for heating at a temperature of 560 to 700 ° C. With this configuration, embrittlement of the composite material C can be further promoted compared to the apparatus of the first invention.

  The pre-impregnation means 14b is a device for impregnating various asbestos-containing composite materials (fixed or cut) with a pre-reaction liquid L2 containing sodium chloride, for example, a second one supplied with the pre-reaction liquid L2. Reaction tank 22 is mentioned. In order to accelerate the impregnation effect, it is desirable to have a heating device and a deaeration device for raising the temperature of the preliminary reaction solution.

  The heat treatment furnace 16 is an apparatus for heating an asbestos-containing composite material impregnated with a pre-reaction solution containing sodium chloride to 560 to 700 ° C., preferably 600 to 700 ° C. And vertical, horizontal, and stalker furnaces. Electricity, gas, petroleum, wood, etc. can be used as the heating source.

  In addition, harmful gases such as fine dust of asbestos and dioxins generated in the heat treatment furnaces 10 and 16 are treated with the rapid cooling devices 23 and 25 and the catalysts or filters 24 and 26, respectively, and then exhausted to the outside. Good. 1 and 3 show the case where the rapid cooling devices 23 and 25 and the filters 24 and 26 are separately provided in the heat treatment furnaces 10 and 16, they come out of these heat treatment furnaces 10 and 16. It is also possible to treat the evolved gas with a single, rapid cooling device and catalyst or filter.

  FIG. 4 shows an asbestos treatment apparatus 1C suitable for use in the asbestos treatment method according to the third invention. This apparatus 1C does not crush asbestos-containing composite material C containing fibrous asbestos and cement. Is an asbestos treatment apparatus suitable when the main reaction liquid L1 can be sufficiently infiltrated into the fibrous (bundle) asbestos. In this case, as in the first and second inventions described above, the brittle asbestos is brittle. There is no need to provide the crystallization means 14 and the crushing means 15, and the composite material C is immersed in a main reaction solution composed of an aqueous solution containing both sodium chloride and calcium chloride, and the main reaction solution is immersed in the composite material C. And then heated at a temperature of 710 to 960 ° C. to break the chemical bond between Mg and Si in the asbestos compound and decompose the fibrous asbestos. In particular, in the third invention, since the embrittlement means 14 is omitted, the main reaction solution contains not only calcium chloride but also sodium chloride in order to decompose the fibrous asbestos in the composite material C. It is an essential structure to contain. By containing sodium chloride, the slate itself can be weakened, and thereby it is possible to efficiently impregnate the fibrous asbestos with calcium chloride.

  And the composite material C which gave the main heating means 3 by the method of the 1st-3rd invention finally decomposes | disassembles the fiber asbestos in the composite material C completely (non-fiber-ized), and is made harmless. Thereafter, it is recovered in the recovery container 28 through water washing or the like as necessary.

Next, the asbestos processing method of the asbestos-containing composite material according to the present invention will be described below.
The present invention relates to an asbestos-containing composite material containing fibrous asbestos and cement, particularly an asbestos-containing high-strength composite material such as a slate material or a water pipe, which is discarded without scattering the fibrous asbestos. An asbestos treatment method for an asbestos-containing composite material that can be effectively decomposed (non-fibrinated). In the first invention, the asbestos-containing composite material is heated to 710-960 ° C. In the second invention, The asbestos-containing composite material is immersed in a pre-reaction solution containing sodium chloride, impregnated with the pre-reaction solution in the composite material, and then heated at a temperature of 560 to 700 ° C., respectively. The composite material is crushed and granulated after reducing the mechanical strength, and then immersed in a main reaction solution containing calcium chloride, and the main reaction solution is immersed in the composite material. And then heating at a temperature of 710 to 960 ° C. to break the chemical bond between Mg and Si in the asbestos compound and decompose (non-fibrous) the fibrous asbestos. The invention is a case where the main reaction liquid can be soaked into the fibrous (bundle) asbestos without crushing in advance, and the asbestos-containing composite material is treated with the preliminary reaction liquid as in the second invention. Without being immersed in a main reaction solution containing both sodium chloride and calcium chloride, the main reaction solution is impregnated in the composite material, and then heated at a temperature of 710 to 960 ° C. to form Mg and the asbestos compound. The purpose is to break the chemical bond of Si and decompose (non-fibrous) fibrous asbestos.

  Generally, asbestos in an asbestos-containing high-strength composite material such as a slate material coexists with bundled fibers and dispersed fine fibers. At the time of production, the bundled fibers are loosened and used as fine fibers. If the loosening operation (defibration operation) is insufficient, the bundled fibers exist. Although there are more fine fibers quantitatively, bundle fibers are also observed at the level of microscopic observation. Although it can be decomposed if the decomposition solution penetrates into the bundle fiber, in the case of a slate material, it is first hardened with a hardened cement and is difficult to soak. The bundled asbestos fibers cannot be sufficiently decomposed only by heating with the main reaction liquid which is a decomposition liquid. Therefore, in the first and second inventions, mechanical crushing treatment is performed as the pretreatment. Is required.

Therefore, in the present invention, the asbestos-containing composite material is impregnated with sodium chloride or a pre-reaction liquid containing both sodium chloride and calcium chloride, and then the asbestos-containing composite material is heated to 560 to 700 ° C (second invention). ), Or by heating the asbestos-containing composite material to 710 to 960 ° C. without impregnating the preliminary reaction solution (first invention), the mechanical strength of the asbestos-containing composite material is significantly reduced and becomes brittle. It can be easily crushed. In view of ease of crushing, it is preferable to heat after impregnating the preliminary reaction liquid. In addition, the 2nd invention which heats an asbestos containing composite material after making an asbestos containing composite material impregnate a preliminary reaction liquid can make heating temperature lower than the 1st invention. This is because when sodium chloride is included and heated, the slate constituent and sodium chloride react to form chloride. When this chloride decomposes at high temperatures, it expands. The expanding energy generated at that time causes minute cracks and cracks to occur in the internal structure of the slate, which makes it easy to decompose. As a result, the proper heating temperature range shifts to the lower side.

  When the asbestos-containing composite material impregnated with a pre-reaction solution containing sodium chloride and thermally decomposed was observed with a scanning electron microscope, fine asbestos was decomposed. Moreover, from the X-ray diffraction analysis, magnesium oxide produced by the decomposition of asbestos was produced. From these things, the fine asbestos was decomposed | disassembled.

In the case of an asbestos-containing high-strength composite material, for example, a slate material that is generally used, fibrous (bundle) asbestos is included. In the conventional method of incineration at a firing temperature of 500 to 600 ° C., bundled asbestos fibers cannot be completely decomposed and may remain undecomposed. Therefore, in the second invention, in order to decompose the bundled asbestos fibers in the slate material, the pre-reaction liquid containing at least sodium chloride is impregnated and heated, then crushed by a mechanical method, and then at least chlorinated. By soaking the asbestos decomposing agent, which is the main reaction solution containing calcium, and then heating, pulverization can be performed much more easily than pulverizing the slate plate before heating. ). The content of calcium chloride in the main reaction solution is preferably 1 to 70 g with respect to 100 ml of water. If it is less than 1 g, asbestos is not sufficiently decomposed, and if it exceeds 70 g, calcium chloride that does not penetrate will cover the surface of the sample and cause problems such as damage to the heating device.
When sodium chloride is also contained in the main reaction solution, the calcium chloride content is 0.7 g to 40 g with respect to 100 ml of water, and the sodium chloride content is 0.3 g to 25 g. preferable. In addition, it is desirable to add sodium chloride to the main reaction solution because a molten salt is formed between the two compounds and a freezing point lowering effect is exhibited, and the melting temperature may be lowered.

  In order to carry out these mechanical pulverization operations, a rotary kiln, a screw kiln, a ball mill, a rod mill, or other equipment having a pulverizing function may be used that has functions such as pulverization, mixing, and grinding simultaneously with heating.

The present invention is a method capable of detoxifying a slate plate having a size of 3 × 6 (90 cm × 180 cm), which is practically a fixed size, without any step of cutting. is there.

  Specifically, a slate decomposing agent, which is a pre-reaction solution containing sodium chloride, is impregnated into a standard slate plate and heated to 560 to 700 ° C. By this heat treatment, the strong slate plate is easily crushed. At this stage, the slate plate becomes strip-like or granular. Next, the asbestos decomposition agent which is the main reaction liquid containing calcium chloride is impregnated and heated to 710 to 960 ° C. so that the inside of the bundle asbestos entangled with the fibrous asbestos which is the reinforcing element in the slate material. Calcium chloride is soaked into the fiber, and the fibrous asbestos is decomposed by heating to a powder form and decomposed (non-fibrous and non-asbestos).

  Cement-asbestos composite materials can be broadly classified into three types: sprayed asbestos, asbestos heat insulating material, and slate material. Of these, slate materials are used in large quantities, and disposal is a problem. Moreover, although it is not a problem now, the process of the water pipe which will be discarded in the future is also a problem in the future. Since the asbestos problem occurred, construction has progressed in the direction of removal. Since the removed used water pipes also contain a large amount of asbestos, they need to be detoxified.

(Prevents scattering of fibrous asbestos in asbestos-containing composites)
When handling an asbestos-containing composite material, it is necessary to prevent it by wetting with water or the like so that asbestos fibers are not scattered. In the present invention, the preliminary reaction liquid and the main reaction liquid can be used for wetting.

(Fracture of composite material containing asbestos and decomposition of asbestos)
The asbestos-containing composite material is most easily crushed when it is impregnated with a pre-reaction solution containing at least sodium chloride and then heated to 560 to 700 ° C, preferably 600 to 700 ° C. Yes, the next easy crushing was when the asbestos-containing composite material was directly heated to 710-960 ° C, preferably 800-900 ° C.

  The fine asbestos fibers contained in the asbestos-containing composite material decomposed when heated to 710-960 ° C. when impregnated with an aqueous calcium chloride solution. In the case where the aqueous calcium chloride solution was not impregnated, it was not decomposed unless heated to 1000 ° C. or higher.

  In addition, in the case of fibrous (bundle) asbestos fibers contained in an asbestos-containing high-strength composite material (slate material), it could not be decomposed only by impregnating a decomposition agent such as an aqueous calcium chloride solution and heating. . On the other hand, it is impregnated with a pre-reaction solution containing sodium chloride and heated at a temperature of 560 to 700 ° C., preferably 600 to 700 ° C. and then pulverized, or the asbestos-containing composite material is 710 to 960 ° C., preferably 800 to After carrying out a pulverizing operation such as heating to 900 ° C. and pulverizing, the main reaction liquid containing calcium chloride is impregnated and heated at a temperature of 710 to 960 ° C., preferably 750 to 850 ° C. Asbestos fibers were crushed into powder.

(Process flow of asbestos-containing composite material)
The process flow of the asbestos processing method according to the present invention is shown below.
[Process flow of the first invention]
Asbestos-containing composite material → Heating (710 to 960 ° C) → Grinding → At least calcium chloride-containing main reaction solution → Heating (710 to 960 ° C)
[Process flow of the second invention]
Asbestos-containing composite material → At least sodium chloride-containing preliminary reaction solution (560 to 700 ° C.) → Grinding → At least calcium chloride-containing main reaction solution → Heating (710 to 960 ° C.)
[Process flow of the third invention]
Composite material containing asbestos → Main reaction solution containing both sodium chloride and calcium chloride → Heating (710-960 ° C)

(Method for confirming asbestos non-fibrosis in asbestos-containing composites)
The present inventors have made the asbestos in the asbestos-containing composite material into a fiber form in a normal use form, and broke this form to decompose the fiber asbestos into a powder form or a granular form to make it harmless. This evaluation was observed with a scanning electron microscope. In order to examine this point in more detail, even if a substance other than asbestos is washed with water or acetic acid, it can be removed and separated as long as it dissolves in acetic acid.

  That is, when the product in which the excess calcium chloride melt or unreacted calcium oxide composite oxide added in the product remains is observed with an electron microscope, the asbestos fiber itself is observed due to the remaining compound. It becomes difficult. However, when washed with water, the molten calcium chloride dissolves in water and can be removed. In addition, when washed with acetic acid, calcium oxide oxide can be dissolved and removed. In particular, an organic acid such as acetic acid is used because it is preferable because the oxide as described above dissolves but asbestos does not dissolve.

(Asbestos presence and decomposition method)
Asbestos (chrysotile) contains magnesium (Mg) and silicon (Si) and has a specific crystal structure, and can be analyzed by X-ray diffraction. The determination of the presence or absence of asbestos in the present invention was performed by this method. Moreover, the decomposition | disassembly of asbestos was determined by the presence or absence of the magnesium oxide which a chemical bond of Mg and Si cut | disconnects and produces | generates.

[Test 1] Examination of pulverization and granulation by heating of asbestos-containing composite material (1) Change of asbestos-containing composite material by heating Place the slate plate, which is an asbestos-containing composite material, manufactured as an industrial product in a crucible, up to 1000 ° C Heated for 2 hours, held at that temperature for 2 hours, allowed to cool, and investigated for properties. The slate plate used in the experiment was manufactured by Yokohama Slate Co., Ltd., and the asbestos content was about 20 [mass%] and the bulk density was 1.54 [g / cm ³ ]. The water content of slate is 0.238 [g-water / cm ³ -slate] (23.8 [vol%]) in terms of surface area and 0.155 [cm ³ -water / g-slate] in terms of weight. (15.5 [mass%]).
When the surface of the slate plate was observed with a scanning electron microscope (SEM), the presence of a large amount of asbestos fibers could be confirmed. Asbestos contained in the slate material was composed of chrysotile asbestos and calcium carbonate from X-ray diffraction analysis.

  Next, in addition to the slate material heated to 1000 ° C., slate materials similarly heated to 700 ° C., 800 ° C., and 900 ° C. were produced. Each slate material was examined for changes in appearance, weight changes, and the like. In addition, the presence or absence of rupture, cracking, crushing, etc., and changes in mechanical strength were measured.

(I) Change in appearance There was no change (expansion, crack, deformation) in the appearance of the heated product at 700 to 900 ° C. The color was gray that was close to the color of the slate plate before firing, and there was no change.

(ii) Observation with scanning electron microscope The presence of fibrous asbestos was observed in each heated product at any temperature.

(iii) Mechanical strength (bending strength) measurement
The bending strength before heating of the slate plate (50 mm × 14 mm × 6.5 mm) was 33.4 MPa, but it decreased to 3.4 MPa when heat-treated at 800 to 1000 ° C. for 2 hours. The elastic modulus was changed from 3.4 GPa to 0.7 GPa. The slate plate was brittle by heating, the deformation amount was large, and the strength was greatly reduced.

(iv) Conclusion Although the strength of the slate plate was reduced by heating at 800 ° C or higher, the asbestos fiber was not decomposed.

(2) Influence on the pulverization of asbestos-containing composites by heating (i) Purpose
In order to decompose and detoxify asbestos in the slate, it is necessary to increase the contact area with the decomposition agent. In order to facilitate pulverization, it is necessary to reduce the strength of a strong slate material. Therefore, it was examined how much the strength is reduced and the pulverization is facilitated only by heating the slate material.

(ii) Experimental method As a sample, a flat asbestos slate plate containing 20% by weight of asbestos (provided by Yokohama Slate Co., Ltd.) was used.
The slate plate was transferred to a magnetic crucible, heated to a predetermined temperature (600 ° C., 700 ° C., 800 ° C.) in 1 hour, held at that temperature for 1 hour, fired, and allowed to cool to room temperature in a desiccator. The obtained sample was subjected to powder X-ray diffraction measurement and observation with a scanning electron microscope.

(iii) Experimental results (ease of grinding in a mortar)
When the firing temperature was 600 ° C., the sample was hard and cracked when cracked. It was hard and difficult to pulverize, and even after grinding, it did not become fine particles.

  When the firing temperature was 700 ° C., it was not as hard as 600 ° C., but was somewhat deteriorated by heating. Although pulverization was easier compared to baking at 600 ° C., fine particles were not easily obtained even after grinding.

  When the firing temperature was 800 ° C., it was completely fragile unlike the 600 ° C. and 700 ° C. fired products. As in the case of heating after impregnating with an aqueous sodium chloride solution, the powder was tattered by simply applying a force vertically. Deterioration was progressing. Grinding was easy and could be ground several times, and the ground particles became fine enough.

(X-ray diffraction)
When the firing temperature was 600 ° C., chrysotile and CaCO ₃ which are constituent materials of slate were observed.
When the firing temperature was 700 ° C., the peak intensity of CaCO ₃ was strong, but the other peaks were low and difficult to identify.
When the firing temperature was 800 ° C., the peaks of Ca ₂ SiO ₄ and CaO were high and there was no chrysotile peak, but what appeared to be a forsterite peak was observed.
The X-ray diffraction pattern of the slate changed greatly when the firing temperature was 600 to 800 ° C. and was different by 100 ° C.

(Scanning electron microscope observation)
When the firing temperature was 600 ° C., the thin fibers were not deteriorated.
When the firing temperature was 700 ° C., the fiber surface deteriorated more than 600 ° C., but undegraded fibers were also observed. Degradation due to heat is not significant.
When the firing temperature was 800 ° C., although there were no fine fibers, bundled fibers were seen and the surface of the fibers was clearly deteriorated.

(iv) Conclusion When the firing temperatures were 600 ° C and 700 ° C, crushing was difficult, both fine fibers and bundled fibers were seen, and asbestos was present.
On the other hand, when the firing temperature was 800 ° C., bundled fibers were observed and asbestos was present, but crushing was easy, and fine fibers were not observed.

(3) Effect of heating on the bending strength of asbestos-containing composites
(i) Purpose
The degree to which the mechanical strength of the slate plate is affected by the heating temperature and the heating time was examined.

(ii) Experimental method As a sample, a flat plate asbestos slate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass% was used.
The slate plate is put in a porcelain crucible and heated up to a predetermined temperature (500 ° C, 600 ° C, 700 ° C, 800 ° C) in 1 hour, and for a predetermined time (30 minutes, 1 hour, 1 hour 30 minutes, 2 hours) Hold and fired. After firing, it was allowed to cool to room temperature in a desiccator.
For the bending strength, the maximum point stress was measured by the following method. The number of samples was three.

Testing machine: Tensilon universal testing machine UCT-1S
Distance between fulcrums: Sample length x 0.8 (mm)
Load full scale: 10gf
Weighting speed: 2.0mm / min
The results of the maximum point stress obtained by measurement are shown below.

As a result, in any case of 500 to 800 ° C., no significant difference was observed in mechanical strength even when the firing time (30 minutes to 2 hours) was changed.
In addition, when firing at 500 ° C., 600 ° C., and 700 ° C., a decrease in mechanical strength is observed compared to before heat treatment, but from the viewpoint of ease of crushing when crushed in a mortar. It could not be easily crushed.
On the other hand, when calcined at 800 ° C., a significant decrease in mechanical strength (6 MPa) was observed compared to the mechanical strength (33 MPa) of the unheated slate plate before heat treatment, and it was ground in a mortar. Sometimes it could be easily crushed.

  The reduction rate of the maximum point stress at each firing temperature was about 80%, particularly at 800 ° C., compared with the unheated slate plate. It is considered that the large decrease in strength at 800 ° C. is caused by elimination of OH groups in the slate. This indicates the elimination of the OH group because of the endothermic peak around 725 ° C. when thermal analysis (TG / DTA) is performed.

(iii) Observation (Ease of grinding in a mortar)
When the firing temperature was 600 ° C., the sample was hard and cracked when cracked. It was hard and difficult to pulverize, and even after grinding, it did not become fine particles.
When the firing temperature was 700 ° C., it was not as hard as firing at 600 ° C., but was somewhat deteriorated by the heat of the cement. Although pulverization was easier compared with baking at 600 ° C., fine particles were not easily obtained even after grinding.
When the firing temperature was 800 ° C., it was completely fragile unlike the 600 ° C. and 700 ° C. fired products. Just by applying a force perpendicularly, it became tattered and powdery and deteriorated considerably. Grinding was easy and could be ground several times, and the ground particles became fine enough.

(Powder X-ray diffraction measurement)
The X-ray diffraction pattern of the heat-treated slate changed greatly when the baking temperature was 600 to 800 ° C. and was different by 100 ° C.
When the firing temperature was 600 ° C., chrysotile and CaCO ₃ which are constituent materials of slate were observed.
When the firing temperature was 700 ° C., the peak intensity of CaCO ₃ was strong, but the other peaks were low and difficult to identify.
When the firing temperature was 800 ° C., the peaks of Ca ₂ SiO ₄ and CaO were high and there was no chrysotile peak, but what appeared to be a forsterite peak was observed.

(Scanning electron microscope observation)
When the firing temperature was 600 ° C., the thin fibers were not deteriorated.
When the firing temperature was 700 ° C., the fiber surface deteriorated more than 600 ° C., but undegraded fibers were also observed. Degradation due to heat is not so great.
When the firing temperature was 800 ° C., although there were no fine fibers, bundled fibers were seen and the surface of the fibers was clearly deteriorated.

(iv) Conclusion When the firing temperatures were 600 ° C and 700 ° C, crushing was difficult, and both fine fibers and bundled fibers remained.
On the other hand, when the firing temperature was 710 to 960 ° C. (here, 800 ° C.), crushing was easy. Moreover, in scanning electron microscope observation, bundle-like fibers were seen, but fine fibers were not seen.

[Test 2] Examination of pulverization and granulation of pre-reaction liquid containing sodium chloride of asbestos-containing composite material by heating (1) Changes in heating of asbestos-containing composite material impregnated with pre-reaction liquid
(i) Experimental Method Asbestos-containing composite material (slate plate) was a flat plate asbestos slate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass%.
A sodium chloride saturated solution (35 g NaCl / 100 ml H ₂ O) was used as the preliminary reaction solution (decomposing agent). A plate-like slate (length: 32.0 mm, width: 16.5 mm, thickness: 5.7 mm, mass: 3.5 g) was placed therein, and impregnated with an aqueous solution for 2 days. The slate plate taken out from the decomposition solution was transferred to a magnetic crucible and heated at a predetermined temperature (600 ° C., 700 ° C., 800 ° C., 900 ° C.) for 2 hours. A muffle furnace was used for heating, which was performed in air and allowed to cool to room temperature. The heated product was subjected to powder X-ray diffraction measurement and observation with a scanning electron microscope.

(ii) Experimental results (appearance, color)
The heated product at 600 ° C., 700 ° C., 800 ° C. and 900 ° C. was neither deformed nor discolored.
(Mechanical strength)
The heated products at 600 ° C., 700 ° C., 800 ° C. and 900 ° C. were all very brittle.

(X-ray diffraction analysis)
Asbestos diffraction lines are not recognized regardless of the heating temperature. Magnesium oxide diffraction lines were observed at any temperature.

(Scanning electron microscope)
600 degreeC, 700 degreeC, and 800 degreeC baked material: The fine asbestos fiber remained. In particular, in the case of 800 ° C., the appearance of asbestos fibers was observed to be degraded.
900 ° C. fired product: The asbestos fiber alone disappeared, but a bundle-like residue was observed.

(iii) Conclusion The asbestos-containing composite material impregnated with the pre-reaction liquid has a heating temperature (firing temperature) of 600 ° C. or higher, which facilitates crushing.

(2) Effects of changes in the concentration of the pre-reaction solution
(i) Purpose Change the concentration of sodium chloride in the pre-reaction solution impregnated in the slate plate, heat it to 700 ° C, perform X-ray diffraction measurement and observation with a scanning electron microscope, and examine the optimum concentration for decomposing the slate. To do.

(ii) Experimental method As the preliminary reaction solution (decomposing agent), two types of 20 g NaCl / 100 ml H ₂ O and 35 g NaCl / 100 ml H ₂ O (saturated solution) were used. A slate plate (length: 32.0mm, width: 16.5mm, thickness: 5.7mm, mass: 3.5g) is immersed in each pre-reaction solution and allowed to stand for 2 hours in a vacuum desiccator whose pressure is reduced by approximately 0.095MPa from atmospheric pressure. The pre-reaction solution was impregnated. After drying, the sample heated at 700 ° C. for 2 hours was subjected to X-ray diffraction measurement and scanning electron microscope observation after washing with acetic acid.

  In the acetic acid treatment, about 60 ml of acetic acid adjusted to pH 5 was added to a sample (100 mg) obtained by pulverizing a heat-fired sample in a mortar to obtain a washing solution. The washing was performed by repeating ultrasonic washing for 30 seconds and standing for 1 minute and 30 seconds 6 times. The washed sample was filtered through a membrane filter having a pore size of 0.2 μm and dried at 110 ° C. The obtained sample was observed with a scanning electron microscope.

(iii) Experimental results The amount of impregnation into the slate due to the difference in the two salt concentrations was compared. When the concentration is 25% (20 g NaCl / 100 ml H ₂ O), the impregnation amount is 0.24 g (7.3%), and when the concentration is 35% (35 g NaCl / 100 ml H ₂ O), the impregnation amount is 0.39 g (11.4%). )Met.
X-ray diffraction analysis showed forsterite in all cases. The diffraction line intensity was lower when the concentration was 35%. When observed with a scanning electron microscope, fine asbestos was decomposed, but thick bundles of asbestos were still observed.

(iv) Conclusion When both slate impregnated with ₂₀ g NaCl / 100 ml H ₂ O and 35 g NaCl / 100 ml H ₂ O pre-reaction liquid is heated at 700 ° C. for 2 hours, crushing is facilitated, the fine fibers are decomposed, Although asbestos formation was observed, bundled fibers were still present.

(3) Influence of immersion time in pre-reaction liquid of asbestos-containing composite material
(i) Purpose Sodium chloride has the effect of reducing the strength of the fired product when impregnated into an asbestos-containing composite material (slate) and heated. Since this action can facilitate the pulverization step, a suitable immersion time of the pre-reaction solution containing sodium chloride was examined from the sensation during pulverization, X-ray diffraction measurement, and scanning electron microscope observation.

(ii) Experimental method The sample was a flat asbestos slate containing asbestos at a rate of 20 mass% (provided by Yokohama Slate Co., Ltd.).
A 20% aqueous sodium chloride solution (20 g / 100 ml H ₂ O) was used as the preliminary reaction solution. Plate slate was immersed in the pre-reaction solution for a predetermined time (10 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, 24 hours) and impregnated. The slate taken out from the preliminary reaction solution was transferred to a magnetic crucible, heated to 700 ° C. over 1 hour, and heated and held (fired) at that temperature for 1 hour. The sample after firing was allowed to cool to room temperature in a desiccator, and powder X-ray diffraction measurement and scanning electron microscope observation were performed.

(iii) Experimental results (appearance observation and fragility)
When the immersion time was 10 minutes, the strength of the slate still remained, and pulverization was difficult.
When the immersion time was 30 minutes to 1 hour, the strength was slightly lower than when it was 10 minutes, but pulverization was still difficult.
When the immersion time was 3 hours, the strength was further reduced, but pulverization was still difficult.
When the immersion time was 6 hours or more, the strength was greatly reduced and the material became brittle and pulverization was easy, but it was not easily shattered.
There was no difference in color and shape between each sample. In all cases, gray and no deformation.
When the immersion time was 6 hours or more, the effect of sodium chloride appeared.

(Powder X-ray diffraction measurement)
In any immersion time, there was a CaCO ₃ peak at around 29 degrees, and a NaCl peak at around 32 degrees. MgO peaks were also observed, and the other peaks were Ca ₅ (SiO ₄ ) ₂ CO ₃ , Ca ₂ (SiO ₄ ), and Ca ₃ Mg (SiO ₄ ) ₂ . No chrysotile peak was observed. In addition, the forsterite peak overlapped with other peaks and could not be identified.

(Scanning electron microscope observation)
Fine asbestos fibers were observed in the sample immersed for 24 hours in a pre-reaction solution containing sodium chloride. In addition, some signs of deterioration were observed on the fiber surface. This is due to the firing temperature being 700 ° C.

(iv) Conclusion The strength of the asbestos-containing composite material (slate) is reduced by immersing it in a pre-reaction solution containing at least sodium chloride for 6 hours or more and firing at 560 to 700 ° C. (700 ° C. in the experimental example here) for 1 hour. It was achieved by doing so and was able to be reduced to the extent that it can be easily pulverized.

[Test 3] Examination of pulverization and granulation by impregnation and heating of main reaction liquid containing both sodium chloride and calcium chloride of composite material containing asbestos (third invention)
(i) Purpose Attempts to decompose asbestos in an asbestos-containing composite material using a main reaction solution in which both sodium chloride, which degrades the asbestos-containing composite material (slate material), and calcium chloride, which promotes the decomposition reaction of asbestos, are mixed. It was.

(ii) Experimental method The main reaction solution was adjusted to have calcium chloride: sodium chloride = 1: 1 (mass ratio 17.5 g / 100 ml H ₂ O each). Plate slate was immersed in this and impregnated with the main reaction liquid for 2 days. The slate taken out from the main reaction solution was transferred to a porcelain crucible, heated to a predetermined temperature (600 ° C., 700 ° C., 800 ° C.) in 1 hour, and then fired for 2 hours. After firing, it was allowed to cool to room temperature in a desiccator.
Analysis of the sample after heating was performed by powder X-ray diffraction measurement and scanning electron microscope observation.

(iii) Experimental results (appearance)
There was almost no change in the appearance after firing, and the surface was whitish gray. There was little change in the cross section, but there was a slightly yellowish portion at a firing temperature of 800 ° C. There was no deformation.

(Hardness)
When the firing temperature was 600 ° C., the strength of the slate decreased somewhat, but it was still hard and pulverization was difficult.
When the firing temperature was 700 ° C., the strength was further reduced as compared with 600 ° C., but pulverization was still difficult.
When the calcination temperature was 800 ° C., the strength was remarkably lowered and the material became brittle and pulverization was easy.

(Electron microscope observation)
When the firing temperature was 600 ° C. and 700 ° C., fine asbestos fibers were observed.
Further, when the firing temperature was 800 ° C., there were almost no thin asbestos fibers or bundle fibers.

(X-ray diffraction)
When the firing temperature was 600 ° C., the peak intensity of chrysotile was low.
When the firing temperature was 700 ° C., the chrysotile peak disappeared and the MgO peak became clear.
When the firing temperature was 800 ° C., most of the peaks belonged to Ca ₂ SiO ₄ . The MgO peak also appeared clearly and the chrysotile peak disappeared.

(iv) Conclusion When the main reaction liquid (decomposing agent) containing both sodium chloride and calcium chloride is used, both fine asbestos and bundled asbestos at 710 ° C or higher (800 ° C in the experimental example here) Disassembled.

[Test 4] Decomposition / detoxification of asbestos in asbestos-containing composite material which was pulverized after impregnation and heating after containing sodium chloride and then impregnated with main reaction solution containing calcium chloride and heated (second invention) )
(i) Purpose From the results of the examination so far, the asbestos-containing composite material (slate plate) is impregnated with a pre-reaction solution containing sodium chloride and calcined at 560 to 700 ° C., preferably 600 to 700 ° C. for 1 hour. Was found to be easily pulverized. Easiness of pulverization was easier when the slate plate was immersed in a pre-reaction solution containing sodium chloride and heated than when heated at 710 to 960 ° C. Also, asbestos-containing composite material (slate plate) was impregnated with a pre-reaction solution containing sodium chloride and heated, but bundled asbestos fibers were undegraded, but the main reaction containing calcium chloride after pulverization It is verified whether asbestos can be effectively decomposed by heating after impregnating the liquid.

  Specifically, the pre-reaction solution containing sodium chloride is impregnated and pulverized after heating, and then the main reaction solution containing calcium chloride is impregnated and fired, so that fine asbestos fibers can also be bundled asbestos fibers. Were also considered to be easily disassembled.

  Since the slate plate is produced firmly, mechanical crushing treatment was necessary to decompose it. Grinding was facilitated by heating after impregnation with a pre-reaction solution containing sodium chloride. The crushing and crushing method includes a normal mortar, ball mill, roller mill, and other crushing methods, and an optimum method is applied depending on the situation at that time.

(ii) Experimental method As a sample, a flat plate asbestos slate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass% was used.
A sodium chloride aqueous solution (20 g NaCl / 100 ml H ₂ O) was used as a preliminary reaction solution. Plate slate was immersed in this and impregnated with the pre-reaction solution for 1 day. The slate plate taken out from the preliminary reaction liquid was transferred to a magnetic crucible, heated to a predetermined temperature (700 ° C.) in 1 hour, and then fired for 1 hour. After firing, the mixture was allowed to cool to room temperature in a desiccator and pulverized using a mortar.
As the main reaction solution, a saturated aqueous solution of calcium chloride (60 g / 100 ml H ₂ O) was used. The amount of saturated calcium chloride aqueous solution (60 g / 100 ml H ₂ O) used as the main reaction solution was the same weight as the sample (slate pulverized product) used in the experiment. The main reaction solution was thoroughly mixed with the crushed sample, and the main reaction solution was soaked into the sample. The immersion time varies depending on the volume and shape of the sample, but is 10 minutes to 24 hours or more, preferably 30 minutes to 3 hours. At that time, it is effective to heat or reduce the pressure. The sample soaked with the main reaction solution was dried overnight in a dryer at 105 ° C. The dried sample was transferred to a magnetic crucible, heated to a predetermined temperature (600 ° C., 700 ° C., 750 ° C., 800 ° C.) in 1 hour, and then fired for 2 hours. These samples were subjected to powder X-ray diffraction measurement and scanning electron microscope observation.
Since the obtained fired sample had deliquescence, there was a possibility that accurate microscopic observation was not possible, and it was washed with acetic acid and the residue was observed.

(iii) Experiment and observation results
(appearance)
The appearances of the samples with different heating (firing) temperatures after impregnation with the main reaction solution were as follows.
When the calcination temperature was 600 ° C., it had a strong white gray color, and the bottom part in contact with the crucible was greenish and was hygroscopic.
When the firing temperature was 700 ° C., the upper surface had a purplish brown color, the bottom surface in contact with the crucible was greenish, and was hygroscopic.
When the calcination temperatures were 750 ° C. and 800 ° C., the upper surface exhibited a dark reddish brownish brown color, the bottom surface in contact with the crucible was greenish, and deliquescence was extremely high.
The deliquescence here means specifically the property that calcium chloride remains undegraded and absorbs moisture in the air and becomes sticky. Therefore, it is necessary to perform analysis or the like after washing with water or acetic acid to remove the remaining calcium chloride.

(X-ray diffraction)
When the firing temperature after impregnation with the main reaction solution was 600 ° C., the main peak of the fired product was Ca ₃ Cl ₂ SiO ₄ . This calcined product is not identified from a calcined product obtained by simply heating a slate plate or a calcined product obtained by only impregnating and heating a pre-reaction solution containing NaCl. Therefore, it is considered that the reaction with CaCl ₂ added after pulverization progressed and formed. In addition, NaCl, CaClOH, MgO, Ca ₂ SiO _{4 and the} like were identified in descending order of peak intensity. When the firing temperature after impregnation with the main reaction solution was 700 ° C., 750 ° C., and 800 ° C., the strength of the X-ray diffraction (XRD) pattern of the fired product was low and amorphous.

(Acetic acid washing test)
The residual rate of the sample in acetic acid cleaning was 9% at 600 ° C., 700 ° C., 750 ° C., and 800 ° C., respectively. Since about 20 mass% of asbestos is contained in the slate used in the experiment, it indicates that the asbestos was decomposed and changed into a substance dissolved in acetic acid.

(Scanning electron microscope observation)
When the firing temperature after impregnation with the main reaction solution is 600 ° C., there are few thick fiber remnants.
When the firing temperature after impregnation of the main reaction liquid is 700 ° C., the absolute number of fibers is larger than that of the 800 ° C. fired product, but it is considerably less when observed as a whole.
When the firing temperature after impregnation with the main reaction solution is 750 ° C. and 800 ° C., almost no fibers are found. The residue after washing was a powdery substance.

(iv) Conclusion Asbestos fibers in the asbestos-containing composite material (slate material) were immersed in a pre-reaction solution containing sodium chloride and heated (fired), and the bundled asbestos fibers were not decomposed (disintegrated). Therefore, the fine asbestos is bundled by adding a pulverization operation and then immersing in a main reaction solution containing calcium chloride and heating (baking) to 710 ° C. or higher (750 ° C. and 800 ° C. in the experimental example here). All the asbestos fibers were also broken down.

[Test 5] Comparison between the method of the first to third inventions (Examples 1 to 3) and the method described in Patent Document 4 (Comparative Example) (I) Demonstration experiment by the method of the first invention (Example 1)
In Example 1, a flat asbestos slate plate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass% was used as a sample. The slate plate was transferred to a magnetic crucible, heated to 800 ° C. over 1 hour, held at that temperature for 1 hour, fired, and allowed to cool to room temperature in a desiccator. Then, after being immersed in a 25% by volume calcium chloride aqueous solution and impregnating, it was put in a crucible and dried in a drier at 110 ° C. Thereafter, the crucible was placed in a muffle furnace, heated from room temperature to 800 ° C. in 2.5 hours, fired at this temperature for 2 hours, and allowed to cool to room temperature in a desiccator to obtain a fired product.
(II) Demonstration experiment by the method of the second invention (Example 2)
Example 2 used a plate asbestos slate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass% as a sample. A sodium chloride aqueous solution (20 g NaCl / 100 ml H ₂ O) was used as a preliminary reaction solution. Plate slate was immersed in this and impregnated with the pre-reaction solution for 1 day. The slate plate taken out from the preliminary reaction liquid was transferred to a magnetic crucible, heated to a predetermined temperature (700 ° C.) in 1 hour, and then fired for 1 hour. After firing, the mixture was allowed to cool to room temperature in a desiccator and pulverized using a mortar. As the main reaction solution, a saturated aqueous solution of calcium chloride (60 g / 100 ml H ₂ O) was used. The amount of saturated aqueous solution of calcium chloride (60 g / 100 ml H ₂ O) used as the main reaction solution was the same weight as the sample (slate pulverized product) used in the experiment. The main reaction solution was thoroughly mixed with the crushed sample, and the main reaction solution was soaked into the sample. The immersion time varies depending on the volume and shape of the sample, but is 10 minutes to 24 hours or more, preferably 30 minutes to 3 hours. At that time, it is effective to heat or reduce the pressure. The sample soaked with the main reaction solution was dried overnight in a dryer at 105 ° C. The dried sample was transferred to a magnetic crucible, heated to 800 ° C. over 1 hour, then fired for 2 hours, and allowed to cool to room temperature in a desiccator to obtain a fired product.
(III) Demonstration experiment by the method of the third invention (Example 3)
In Example 3, a flat asbestos slate plate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass% was used as a sample. The main reaction solution was adjusted to have calcium chloride: sodium chloride = 1: 1 (mass ratio 17.5 g / 100 ml H ₂ O each). Plate slate was immersed in this and impregnated with the main reaction liquid for 2 days. The slate taken out from the main reaction solution was transferred to a porcelain crucible, heated to a predetermined temperature of 800 ° C. over 1 hour, then fired for 2 hours, and allowed to cool to room temperature in a desiccator to obtain a fired product.
(IV) Demonstration experiment by the method described in Patent Document 4 (comparative example)
In the comparative example, a flat asbestos slate plate (provided by Yokohama Slate Co., Ltd.) containing asbestos at a rate of 20 mass% was used as a sample. The slate plate was transferred to a magnetic crucible and immersed in a calcium chloride solution for 2 days. After soaking, it was dried in air, heated to 800 ° C. over 1 hour, held at that temperature for 1 hour, fired, and allowed to cool to room temperature in a desiccator to obtain a fired product.
(Performance evaluation)
The results of evaluating the physical properties of each fired product are as follows.
1. Analysis Results by Powder X-ray Diffraction Method All the fired products obtained in Examples 1 to 3 were confirmed to have magnesium oxide (MgO) diffraction lines. The presence of magnesium oxide indicates that the chemical bond between Si and Mg, which are constituent elements of asbestos, has been broken, which means that asbestos has been decomposed. On the other hand, in the comparative example, the diffraction line of forsterite in which the asbestos component was thermally decomposed was confirmed, and the diffraction line of magnesium oxide (MgO) could not be confirmed.
2. Observation Example 1 by Scanning Electron Microscope (SEM) Asbestos was granular, and the fibrous form of the original asbestos was not observed. In Example 2, almost no fiber was found, and the residue after washing was observed. As a result, all fine asbestos and bundled asbestos fibers were decomposed by the powdery substance. In Example 3, both fine asbestos fibers and bundled fibers were decomposed. On the other hand, the fired product treated in the comparative example was harder and harder to crush than before the treatment. Therefore, it was crushed with a hammer and the sample taken from the inside was observed with a scanning electron microscope. The state of disassembling was not observed.
(V) Conclusion From the results of Test 5 described above, the first to third inventions are superior to the invention described in Patent Document 1 in the ability to treat asbestos in an asbestos-containing high-strength composite material such as a slate material. It was.

  In the example of the above embodiment, the case where the composite material C is a slate material has been described as an example. However, the same test is performed on the water pipe, and the same result as in the case of the slate material is obtained. Has been confirmed by another experiment.

  In addition, from the viewpoint of reducing the reaction temperature between asbestos and calcium and increasing the uniformity of the reaction by forming a molten salt, the main reaction solution further includes an auxiliary additive compound that forms a molten salt at low temperature in calcium chloride. It is preferable to contain. Examples of the molten salt system that can be used include the following systems.

Systems that melt at around 500 ° C-KCl-NaCl-CaCl ₂ , KCl-CaCl ₂ -MgCl ₂ , NaCl-CaCl ₂
Systems that melt from around 600 ° C -BaCl ₂ -CaCl ₂ , NaCl-CaCl ₂ -NaF-CaF ₂
Melts from the vicinity of 650 ℃ system -CaCl ₂ -CaF ₂

In addition, since the fluorine compound contains chlorofluorocarbon, which is an ozone depleting substance, it has a problem in processing the product, and the Ba compound is expensive. MgCl ₂ has a vapor pressure of 1 mmHg. It is 778 ° C, NaCl is 865 ° C, KCl is 821 ° C, and since the vapor pressure of the salt is high near the reaction temperature, these compounds can be used by using a molten salt appropriately contained as necessary. Good.

As a molten salt for melting asbestos, it is possible to apply other than the above system. There are other system changes due to the addition of trace amounts of salts.
Further, even when containing a salt having a high vapor pressure such as AlCl ₃ or FeCl ₃ , it is considered that the decomposition reaction of asbestos occurs at 600 to 800 ° C.

  In the above-mentioned examples and comparative examples, both are shown as examples in which chrysotile type asbestos is used as asbestos, but the method of the present invention can be applied to other methods such as crocidolite, amosite, anthophyllite, tremolite, actinolite, Needless to say, it can also be applied to asbestos.

  What has been described above is merely an example of an embodiment of the present invention, and various modifications can be made within the scope of the claims.

  According to the present invention, an asbestos-containing composite material containing fibrous asbestos and cement, in particular, an asbestos-containing high-strength composite material such as a slate material or a water pipe to be discarded, without scattering the fibrous asbestos. It has become possible to provide an asbestos treatment method for an asbestos-containing composite material that can effectively make asbestos non-fibrous.

It is the schematic of the asbestos processing apparatus suitable for using for the asbestos processing method of the asbestos containing composite material according to 1st invention. FIG. 2 is an enlarged view of only an apparatus for moving a composite material constituting the main heating means constituting the asbestos treatment apparatus of FIG. 1, wherein (a) is a plan view and (b) is a side view. . It is the schematic of the asbestos processing apparatus suitable for using for the asbestos processing method of the asbestos containing composite material according to 2nd invention. It is the schematic of the asbestos processing apparatus suitable for using for the asbestos processing method of the asbestos containing composite material according to 3rd invention.

Explanation of symbols

1A, 1B, 1C Asbestos treatment equipment 2 Main impregnation means (or main impregnation equipment)
3 Main heating means (or main heating device)
4 First reaction tank 5 Sodium chloride aqueous solution tank 6 Water tank 7 Sodium chloride and calcium chloride mixed aqueous solution tank 8 Calcium chloride aqueous solution tank 9 Valve
10, 16 Heat treatment furnace
11 Screw
12, 17 Belt conveyor
13a Heat treatment furnace inlet
13b Heat treatment furnace outlet
14 Brittle means
14a Preheating means
14b Pre-impregnation means
15 Crushing means (or crushing device)
18 axis of rotation
19 Rotating blade
20 Crushing section
21 nozzles
22 Second reactor
23, 25 Rapid cooling system
24, 26 filters
28 Collection container

Claims (9)

  An asbestos-containing composite material containing fibrous asbestos and cement is heated to 710 to 960 ° C. to reduce the mechanical strength of the composite material, and then the composite material is crushed into granules, and then calcium chloride or chloride The main reaction solution is immersed in the main reaction solution containing both calcium and sodium chloride, and the main reaction solution is impregnated in the composite material, and then heated at a temperature of 710 to 960 ° C. to chemistry of Mg and Si in the asbestos compound An asbestos treatment method for an asbestos-containing composite material, characterized by breaking bonds and decomposing fibrous asbestos.   An asbestos-containing composite material containing fibrous asbestos and cement is immersed in a pre-reaction solution containing sodium chloride or both sodium chloride and calcium chloride so that the pre-reaction solution is impregnated in the composite material. Heat at a temperature of ˜700 ° C. to reduce the mechanical strength of the composite material, then crush the composite material into granules, then immerse in the main reaction solution containing calcium chloride or both calcium chloride and sodium chloride The main reaction liquid is impregnated into the composite material, and then heated at a temperature of 710 to 960 ° C. to break the chemical bond between Mg and Si in the asbestos compound, thereby decomposing fibrous asbestos. An asbestos treatment method for an asbestos-containing composite material.   An asbestos-containing composite material containing fibrous asbestos and cement is immersed in a main reaction solution containing both sodium chloride and calcium chloride so that the main reaction solution is impregnated in the composite material, and then 710 to 960 ° C. An asbestos treatment method for an asbestos-containing composite material, wherein the asbestos-containing composite material is decomposed by heating at a temperature of 5 to break a chemical bond between Mg and Si in the asbestos compound.   The method of asbestos treatment of an asbestos-containing composite material according to claim 1, 2 or 3, wherein the composite material is an asbestos-containing high-strength composite material such as a slate material or a water pipe.   The said main reaction liquid is an asbestos treatment method of the asbestos containing composite material of any one of Claims 1-4 which further contains the auxiliary | assistant addition compound which forms molten salt in calcium chloride at low temperature. Main impregnation means for immersing an asbestos-containing composite material containing fibrous asbestos and cement in a main reaction solution containing calcium chloride or both calcium chloride and sodium chloride, and impregnating the main reaction solution into the composite material; ,
By heating the composite material impregnated with the main reaction liquid by the main impregnation means at a temperature of 710 to 960 ° C., the chemical bond between Mg and Si of the asbestos compound in the composite material is cut, and fibrous asbestos An asbestos treatment apparatus for an asbestos-containing composite material, comprising: a main heating means for decomposing the powder into a granular or powder form.   The asbestos-containing composition according to claim 6, further comprising embrittlement means for reducing the mechanical strength of the asbestos-containing composite material, and a crushing means for crushing the composite material whose mechanical strength has been reduced by the embrittlement means into a granular shape. Composite asbestos processing equipment.   The asbestos treatment apparatus for asbestos-containing composite material according to claim 7, wherein the embrittlement means is preheating means for heating the asbestos-containing composite material at a temperature of 710 to 960 ° C.   Pre-impregnation heating in which the embrittlement means heats the composite material impregnated with sodium chloride or a pre-reaction solution containing both sodium chloride and calcium chloride at a temperature of 560 to 700 ° C. The asbestos processing apparatus of the asbestos containing composite material of Claim 7 which is a means.

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