JP4828912B2 - Decomposition method of asbestos - Google Patents

Description

In the present invention, asbestos and / or an asbestos-containing substance are decomposed simultaneously with chlorofluorocarbon or halon or sulfur hexafluoride using superheated steam, specifically, a process for decomposing chlorofluorocarbon or halon or sulfur hexafluoride using superheated steam. The present invention relates to a method for decomposing asbestos that is decomposed by the presence / supply of asbestos therein.

  Asbestos is a kind of naturally occurring mineral fiber, including serpentinite chrysotile and amphibole amosite. This asbestos has a fine fiber structure with strength, has a large surface area compared to its weight, and has excellent heat resistance, chemical resistance, and insulation, so it is nonflammable construction material , Used widely in electrical products, automobiles, household goods and other applications. However, use is prohibited in October 2004. As a reason, it has been pointed out that if a human inhales even a small amount, it will cause mesothelioma, asbestosis, lung cancer, etc. several decades later, and it is now a big social problem as a health destructive substance.

  Asbestos may be used alone or as a composite material. Asbestos is used alone in spinning products such as strings, tapes, and fabrics, and asbestos-cement composite material is a fireproof coating for steel frames. Used as part of the material. In the case of intermediate treatment of these asbestos, only melting is recognized, but since heat resistance is strong, it is necessary to heat to 1000 ° C. or higher for detoxification treatment, and the treatment cost increases, so most of them are final disposal sites. The present situation is that the landfill process is carried out with or the landfill process is performed after melting.

Patent Document 1 discloses a water treatment with a larger content of CaO than SiO ₂ for asbestos with the aim of greatly reducing the cost of melting asbestos and preventing secondary pollution after landfill treatment. High temperature hearth in which sludge is mixed as a basicity adjusting agent / binder, the weight concentration ratio of SiO ₂ and CaO in the mixture is adjusted, the ratio adjusted mixture is molded, and the molding mixture is formed of a carbon-based combustible material Asbestos melt treatment method is described in which the melt is heated and melted.

  In Patent Document 2, an electric melting furnace is provided in which a furnace body and a furnace lid are combined, and the inside of the furnace is hermetically sealed, and a charging chute is provided through the furnace lid along the outside of the furnace. At the end facing the outside of the furnace of the chute, there is provided a charging part for guiding a plastic storage bag in which waste asbestos material is hermetically sealed to the charging chute, and the storage bag charged from this charging part is supplied to the charging chute A pushing device is provided, and a chute path is provided in the throwing chute for guiding the holding bag pushed by the pushing device while holding it, and an end of the throwing chute facing the furnace is provided at the lower end of the chute path. A waste asbestos material melting apparatus provided with a discharge port for discharging the containing bag into the furnace is described.

  In Patent Document 3, for the purpose of providing a detoxification treatment method for asbestos that can reliably detoxify asbestos with low energy, asbestos and chlorofluorocarbon decomposition products produced by detoxification treatment with chlorofluorocarbon are mixed, A treatment method is disclosed in which the mixture is heat treated at a low temperature. Moreover, the substance containing asbestos and the CFC decomposition product are mixed, and then the mixture is subjected to low-temperature heat treatment. When the asbestos-containing substance is porous, it is rendered harmless by low-temperature heat treatment after impregnation with a slurry-like fluorocarbon decomposition product.

  On the other hand, chlorofluorocarbon gas, which has been used as a refrigerant or spray agent, and halon gas or sulfur hexafluoride gas, which has been used as a digestive agent, are environmental pollutants. Therefore, various measures to detoxify these substances Means have been proposed. For example, hydrothermal reaction methods, incineration methods, explosion reaction decomposition methods, microbial decomposition methods, ultrasonic decomposition methods, plasma reaction methods, and the like have been proposed for chlorofluorocarbon gas treatment methods. In the hydrothermal reaction method, for example, chlorofluorocarbon gas can be decomposed into safe substances such as sodium chloride and carbon dioxide.

Regarding equipment for realizing the hydrothermal reaction method, processing experiments using an autoclave in the laboratory, for example, the mixing ratio of caustic soda solution, ethanol, chlorofluorocarbon solution, temperature setting value, pressure setting value and reaction time setting Although experiments on the values have been carried out, the hydrothermal reaction is usually carried out at 300 to 450 ° C. while maintaining the high temperature and high pressure conditions of 100 to 250 kg / cm ² .

  The applicant of the present application previously proposed a method and apparatus for treating environmental pollutants by hydrothermal reaction treatment according to Patent Document 4. Briefly, the tank contains a mixture of chlorofluorocarbon, caustic soda, and ethanol, which is sent to the heat exchanger via a pump and a flow meter, reacted again in the hydrothermal reactor, and then again. It is sent to a cooler via a heat exchanger, and sent from the cooler to a separator via a pressure control valve for flow rate control to separate into clean water and clean matter.

  However, the hydrothermal reactor must maintain high-temperature and high-pressure conditions, and the mechanism for pumping and discharging the solid-liquid mixture under high temperature and high pressure is complicated and the structure needs to be changed depending on the type of substance to be decomposed. However, there is a problem that it is difficult to control the operation, and there is still a problem from the viewpoint of ensuring safety.

  In response to the above, further, the applicant of the present application can select a material that constitutes the apparatus according to Patent Document 5 by allowing the decomposition of hardly decomposed substances under normal pressure without causing damage to the piping or the discharge valve due to high temperature and pressure. A decomposition method and its apparatus that can be selected are proposed. That is, the fluorocarbon charged in the decomposition target tank and the water charged in the water tank are sent to the heater through the pipe, and the internal heater and the external heater arranged in advance in the heater are operated to make the inside of the heater 500 Superheated steam is generated by heating to 750C to 750C. Since the temperature of the superheated steam necessary for the decomposition treatment varies depending on the object to be decomposed, it is set according to the object to be decomposed. For example, in the case of chlorofluorocarbon gas, the superheated steam is 500 ° C. to 750 ° C. and polyethylene is about 400 ° C.

Furthermore, the applicant of the present invention is able to decompose environmentally hazardous substances such as Freon gas, polyethylene, plastic, wood, organic compounds with benzene nuclei and other industrial wastes, and other industrial decomposable substances at normal pressure, resulting from high temperature and pressure. In order to provide a method and apparatus for decomposing a hardly decomposable substance that has an improved decomposition rate even when water is used as a solvent without causing damage to the piping or discharge valve to be decomposed, according to Patent Document 6, The mixture of the solvent and the solvent is heated to generate steam, the steam is further heated to a predetermined temperature to form superheated steam, and the superheated steam is heated to the predetermined temperature in a normal pressure reactor. We proposed a method for decomposing a hardly decomposable substance that decomposes the object to be decomposed by allowing the reaction time to pass.
Japanese Patent No. 3085959 Japanese Patent No. 3359964 JP 2005-168632 A Japanese Patent No. 2612249 Japanese Patent No. 3219706 Japanese Patent No. 3219689

  As described above, in order to detoxify asbestos, it has to be heated to a high temperature of around 1500 ° C. by an electric furnace or the like, and there is a problem that the cost of facility and electric power becomes high, and the landfill treatment is performed. In some cases, asbestos must be sealed twice in a plastic bag or sealed in a solid container and solidified with cement, etc., and buried to a depth of 2 meters or more, which increases processing costs and time. There is a concern that secondary solid pollution may occur due to the destruction of the solidified concrete with the passage of time and asbestos flowing out or scattered from the ground, and there is a problem that the detoxification treatment cannot be perfected.

Further, the asbestos detoxification treatment method described in Patent Document 3 and the like uses calcium hydroxide Ca (OH) ₂ to neutralize carbon dioxide CO ₂ , hydrogen fluoride HF, and hydrochloric acid HCl generated during the decomposition of CFCs. It is used as a neutralizing agent, and calcium carbonate CaCO ₃ , calcium fluoride CaF ₂ , and calcium chloride CaCl ₂ are generated by the reaction to form a residue. Of these, calcium chloride CaCl ₂ dissolves in water. For example, CaCO ₃ and calcium fluoride CaF ₂ remain. This residue and asbestos can be mixed and heated at about 700 ° C. to change to a substance different from asbestos. However, asbestos cannot be simultaneously decomposed in the process of decomposing chlorofluorocarbon, and there is a problem that a complicated process for neutralizing HF and HCl generated at the time of decomposing chlorofluorocarbon is required. In addition, it is necessary to remove calcium chloride by washing, and it is also necessary to mix the CFC decomposition product and asbestos.

Therefore, in view of the above-mentioned conventional problems, the present invention more easily and simultaneously decomposes asbestos and / or asbestos-containing substances, which are health-damaging substances, which are social problems, The purpose is to provide an asbestos decomposition method that can realize not only Freon decomposition but also asbestos decomposition processing with high efficiency and low cost.

The present invention, in order to achieve the above object, a method of decomposing asbestos and / or asbestos-containing material, by utilizing the heat generated during chlorofluorocarbon decomposition using 700 ° C. to 800 ° C. superheated steam as the decomposition products A method of decomposing a substance to be decomposed together with chlorofluorocarbon by retaining the asbestos and / or asbestos-containing substance as a substance to be decomposed in a treatment furnace together with superheated steam and chlorofluorocarbon at 700 ° C. to 800 ° C. for a certain period of time. Provide as basic. Also, asbestos and / or asbestos-containing material as a material to be decomposed is allowed to elapse with a predetermined reaction time in a processing furnace heated to a predetermined temperature together with superheated steam and flon at 700 ° C. to 800 ° C. A method for decomposing a material to be decomposed is provided.

Further, asbestos and / or asbestos-containing material as a decomposition target product is put into a processing furnace heated to a predetermined temperature, and superheated steam and Freon gas at 700 ° C. to 800 ° C. are supplied into the processing furnace for a predetermined reaction time. A method of decomposing the object to be decomposed together with chlorofluorocarbon by passing it through, a method of introducing the gas discharged from the processing furnace to the exhaust gas scrubber, cleaning it with the cleaning liquid, and then sucking it with a blower through the filter and diffusing it outside the system The gas discharged from the processing furnace is guided to an exhaust gas decomposition apparatus heated to a predetermined temperature, and superheated steam is injected into the exhaust gas decomposition apparatus to cause a reaction, and the gas discharged from the exhaust gas decomposition apparatus is supplied to an exhaust gas scrubber. Provided is a method of guiding and cleaning with a cleaning liquid, and then sucking with a blower through a filter and dissipating out of the system.

Then, in the treatment furnace, a method of introducing a reaction accelerator together with chlorofluorocarbon gas and superheated steam and reacting for a predetermined time, one or more selected from limestone, quicklime, slaked lime, gypsum and cement as the reaction accelerator Thus, a method of reacting for a predetermined time is provided. In addition, a method of heating a processing furnace in a temperature range of 700 ° C. to 800 ° C., a method of disposing a screw that is rotationally driven by a motor in the processing furnace to convey an object to be decomposed, and replacing chlorofluorocarbon with halon The method used and a method using sulfur hexafluoride instead of Freon are provided.

According to the method for decomposing asbestos according to the present invention, asbestos and / or an asbestos-containing substance which is a social problem as a health destructive substance is decomposed simultaneously with the decomposition of chlorofluorocarbon, halon or sulfur hexafluoride which is a hardly decomposable substance. It is possible. That is, it becomes possible to decompose asbestos, which is a health destructive substance, using Freon gas, which is an environmentally destructive substance and is a hardly decomposable substance. Moreover, since it is not necessary to heat the material to be decomposed to a high temperature of around 1500 ° C. as in the conventional asbestos detoxification treatment, it is possible to reduce costs such as facility costs and power costs, and when landfill treatment is performed. As a result, there is no possibility of secondary pollution such as outflow and scattering of asbestos from the ground, and the detoxification treatment can be perfected.

  In the present invention, asbestos and / or an asbestos-containing substance are present together with flon, halon, or sulfur hexafluoride in an atmosphere of superheated steam capable of decomposing flon at about 700 ° C. to 800 ° C. Asbestos can be decomposed, and at that time, hydrogen fluoride HF and hydrochloric acid HCl directly act on asbestos and decompose. In addition, when mixed with one or more selected from limestone, quicklime, slaked lime, gypsum, and cement, hydrogen fluoride HF and hydrochloric acid HCl produced during the decomposition of CFCs can be neutralized on the spot, and further heat of neutralization Can be used for decomposition, the subsequent process can be simplified, the amount of residue (necessary for industrial waste treatment) can be reduced, and the decomposed product can be changed to a more stable simple substance.

  Since the inside of the processing furnace is not forcibly pressurized during the asbestos decomposition process, a high-pressure pump or the like is not required, and there is no concern about damage to valves or piping caused by high pressure. The problem of scattering is eliminated, and since all the reactions are closed systems that occur in the processing furnace and the exhaust gas decomposition apparatus, there is an effect that there is no secondary contamination. In addition, it is possible to control the degree of decomposition by arbitrarily setting the reaction time and temperature, and the detoxified asbestos decomposition products are either buried in the ground or quarried as aggregates for various buildings. Can be used instead.

  Furthermore, according to the present invention, since the process proceeds at a relatively low temperature under normal pressure or slightly negative pressure in the processing furnace and the exhaust gas decomposition apparatus, the material of the processing furnace may be any material that can withstand a predetermined temperature. In addition, there is no risk of asbestos flying out of the system even if the processing furnace and exhaust gas decomposition equipment are damaged, so it is designed to withstand mechanical strength and tensile stress or thermal stress. Has the advantage that it is not required, and measures against damage to various devices are easy and have high safety.

In addition, it is difficult to visually distinguish asbestos and / or asbestos-containing substances from asbestos-like products, and it is difficult to identify them without analysis by X-ray diffraction, etc., and they are separated when they are mixed at the time of collection. Although it is almost impossible, according to the present invention, even if an asbestos-like product is mixed, it can be decomposed without any problem. Therefore, by decomposing asbestos and / or asbestos-containing material simultaneously with the decomposition treatment of chlorofluorocarbon, which is a hardly decomposable substance, the asbestos decomposition treatment method can realize not only chlorofluorocarbon decomposition but also asbestos decomposition treatment with high efficiency and low cost. Can be provided.

The best embodiment of the asbestos decomposition method according to the present invention will be described below with reference to the drawings. In addition, although it demonstrates based on the example using CFC-22 (CFC-22) as an embodiment, it can use other CFCs as long as it is CFCs, and of course, CFC instead of CFCs or hexafluoride. Sulfur can be used, and other halogen-containing substances can also be used. FIG. 1 is a system diagram schematically showing a first embodiment of the present invention. FIG. 2 is a flowchart of the first embodiment. In the figure, 1 is a batch processing furnace, 2 is a heater, and 3 is a chlorofluorocarbon gas inlet. 4 is a superheated steam inlet, 5 is a stirrer, 6 is a stirring blade, 7 is an exhaust gas scrubber, 8 is a filter, 9 is a blower, 12 is a treated product discharge port, 16 is dropped into a treated product tank 17 It is a valve to make it.

  According to the first embodiment, first, the material to be decomposed 10 made of asbestos and / or an asbestos-containing substance is first placed in the batch type processing furnace 1, and the processing furnace 1 is generally 700 ° C. to 800 ° C. using the heater 2. The agitator 5 and the stirring blade 6 are heated in a temperature range of 0 ° C. and injected into the treatment furnace 1 maintained at normal pressure or slightly negative pressure from the Freon gas inlet 3 and the superheated steam inlet 4 respectively. Thus, the object to be decomposed 10 is stirred and allowed to react for an appropriate time. The object to be decomposed 10 is directly thermally decomposed by the action of hydrogen fluoride HF and hydrochloric acid HCl generated at the time of chlorofluorocarbon decomposition.

  And the gas discharged | emitted from the batch type processing furnace 1 is guide | induced to the waste gas cleaner 7, and it wash | cleans using a washing | cleaning liquid, Then, it attracts | sucks with the blower 9 through the filter 8, and diffuses out of the system. The filter 8 is provided assuming that asbestos is mixed in the exhaust gas. Since the use of the filter 8 is expected to increase the passage resistance, the inside of the system is sucked by the blower 9 and the inside of the processing furnace 1 is maintained at normal pressure or slightly negative pressure. The decomposed asbestos and / or the asbestos-containing substance are dropped from the treated product discharge port 12 to the treated product tank 17 through the valve 16.

  The inside of the processing furnace 1 is not pressurized but is at normal pressure or slightly negative pressure, and unlike the conventional high-pressure hydrothermal reactor, the suction action of the blower 9 is used without forcible pressure. It is one of the features of the present invention that the object to be decomposed 10 can be decomposed by the open type apparatus.

  FIG. 3 is a system diagram schematically showing the second embodiment of the present invention, and FIG. 4 is a flowchart of the second embodiment. The same components as those in the first embodiment are indicated by the same reference numerals. It is. 1 is a batch processing furnace, 2 is a heater, 3 is a fluorocarbon gas inlet, 4 is a superheated steam inlet, 11 is a slaked lime inlet as a reaction accelerator, 5 is a stirrer, 6 is a stirring blade, and 13 is an exhaust gas decomposition device , 14 is a heater, 15 is a superheated steam inlet, 7 is an exhaust gas scrubber, 8 is a filter, 9 is a blower, 12 is a treated product outlet, and 16 is a valve for dropping the treated product into the treated product tank 17. .

According to the second embodiment, first, the material to be decomposed 10 made of asbestos and / or an asbestos-containing substance is introduced into the batch-type treatment furnace 1, and an appropriate amount of slaked lime is introduced from the slaked lime inlet 11, and then the heater 2. The CFC and the superheated steam were maintained at normal pressure or slightly negative pressure from the CFC gas inlet 3 and the superheated steam inlet 4, respectively, while heating the processing furnace 1 in the whole temperature range of 700 ° C to 800 ° C. While being injected into the processing furnace 1, the material to be decomposed 10 is stirred by the stirrer 5 and the stirring blade 6 and allowed to react for an appropriate time. In addition, instead of slaked lime (calcium hydroxide Ca (OH) ₂ ) as a reaction accelerator, limestone (calcium carbonate CaCO ₃ ), quick lime (calcium oxide CaO), gypsum (calcium sulfate CaSO ₄ ), cement (main component is CaO) , SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ ).

  Then, the processed object 10 to be decomposed is discharged from the processed material discharge port 12 and the gas discharged from the processing furnace 1 is guided to the exhaust gas decomposition device 13, and the exhaust gas decomposition device 13 is heated as a whole using the heater 14. Then, superheated steam is injected from the superheated steam inlet 15 to react. Next, the gas discharged from the exhaust gas decomposing device 13 is guided to the exhaust gas scrubber 7 and cleaned with the cleaning liquid, and then sucked by the blower 9 through the filter 8 and diffused out of the system. The decomposed asbestos and / or the asbestos-containing substance are dropped from the treated product discharge port 12 to the treated product tank 17 through the valve 16.

  In the second embodiment, it is assumed that chlorofluorocarbons and other harmful gases remain in the gas discharged from the processing furnace 1, and these harmful gases are exhausted in the exhaust gas decomposition apparatus 13. It is characterized by decomposing and detoxifying again with superheated steam.

FIG. 5 is a system diagram schematically showing the third embodiment of the present invention, and FIG. 6 is a flowchart of the third embodiment. The same components as those in the first embodiment are denoted by the same reference numerals. It is. That is, 1 is a batch type processing furnace, 2 is a heater, 3 is a chlorofluorocarbon gas inlet, 4 is a superheated steam inlet, 11 is a slaked lime inlet as a reaction accelerator, 23 is a material to be decomposed, and 12 is a processed material A discharge port, 16 is a valve, and 17 is a processed product tank. A screw 19 that is rotationally driven by a motor 18 is provided in the processing furnace 1. 13 is an exhaust gas decomposition device, 14 is a heater, 15 is a superheated steam inlet, 7 is an exhaust gas scrubber, 8 is a filter, and 9 is a blower. The exhaust gas decomposing apparatus 13 is an apparatus for performing a decomposing process by reacting a gas discharged from the processing furnace 1 with superheated steam for a predetermined time while maintaining a predetermined temperature. In addition, instead of slaked lime (calcium hydroxide Ca (OH) ₂ ) as a reaction accelerator, limestone (calcium carbonate CaCO ₃ ), quick lime (calcium oxide CaO), gypsum (calcium sulfate CaSO ₄ ), cement (main component is CaO) , SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ ).

  According to the third embodiment, first, the material to be decomposed 10 made of asbestos and / or an asbestos-containing substance is continuously charged from the material to be decomposed material inlet 23 into the processing furnace 1, and an appropriate amount is supplied from the slaked lime inlet 11. After heating slaked lime, the processing furnace 1 is heated in the whole temperature range of 700 ° C. to 800 ° C. using the heater 2, and the chlorofluorocarbon gas and superheated steam are respectively supplied from the chlorofluorocarbon gas inlet 3 and the superheated steam inlet 4 to normal pressure. Or, it is injected into the processing furnace 1 maintained at a slight negative pressure, and the screw 19 is rotationally driven by a motor 18 attached to the processing furnace 1 so that the object 10 to be decomposed is conveyed in the processing furnace 1. Let the reaction take place for a long time. Then, the valve 16 is opened to drop the processed material from the processed material discharge port 12 into the processed material tank 17.

  Further, the gas discharged from the processing furnace 1 is guided to the exhaust gas decomposition apparatus 13, and superheated steam is injected from the superheated steam inlet 15 while heating the exhaust gas decomposition apparatus 13 as a whole using the heater 14, and then reacted. Then, the gas discharged from the exhaust gas decomposing apparatus 13 is guided to the exhaust gas scrubber 7, cleaned with the cleaning liquid, sucked with the blower 9 through the filter 8, and diffused out of the system.

  A slight negative pressure is naturally generated in the processing furnace 1 and the exhaust gas decomposition apparatus 13 by the suction action of the blower 9 together with the flow of the superheated steam, and the gas is transferred by the pressure gradient. In the present invention, normal pressure or slight negative pressure means that the exhaust port is opened and sucked by the blower 9 without forcibly increasing the pressure as in the conventional hydrothermal reactor. ing.

In each of the above-described embodiments, examples have been described in which asbestos and / or an asbestos-containing substance is decomposed simultaneously with the decomposition of chlorofluorocarbon, which is a hardly decomposable substance. However, in the present invention, not only chlorofluorocarbon gas but also generally used as a digestive agent is used. It can be decomposed in the same manner as chlorofluorocarbon by injecting halon gas (for example, CF ₃ Br or other halo gas) or sulfur hexafluoride (SF ₆ ).

FIG. 7 is a diagram obtained by analyzing the processing result according to the third embodiment by X-ray diffraction. The temperature in the processing furnace 1 is 800 ° C., the flow rate of the fluorocarbon gas is 2 kg / h, and the superheated steam flow rate is 1 kg / h. (A) in the figure is the result of treating 1 kg of asbestos spray material as the material to be decomposed 5 for 5 minutes, and no asbestos peak is detected. Therefore, it turns out that asbestos is decomposed | disassembled. Next, (B) shows the result of treating for 10 minutes a mixture of 1 kg of asbestos spraying material and 1 kg of slaked lime Ca (OH) ₂ as the object to be treated 10. Asbestos was not detected, calcium fluoride CaF ₂ was detected as a product, and other products could not be identified. (C) is a composition of 1 kg of the spray material itself, and the spray material is made of asbestos and silicon oxide SiO ₂ . (D) shows the analysis result of natural chrysotile asbestos.

Fig. 8 is a diagram analyzed by X-ray diffraction after processing with a flow rate of chlorofluorocarbon of 2 kg / h and a superheated steam flow rate of 1 kg / h, changing the temperature in the processing furnace 1, and (E) is a process to be decomposed. It is a result of processing 1 kg of asbestos spray material as the object 10 at 600 ° C., and asbestos is detected a little, and it can be seen that the decomposition is insufficient. (F) has shown the result of having processed what mixed 1 kg of asbestos spray materials and 1 kg of slaked lime Ca (OH) ₂ at 1: 1 as the material to be decomposed 10 at 600 ° C. Calcium fluoride CaF ₂ was detected together with asbestos Mg ₃ Si ₂ O ₅ (OH) ₄ . (G) is the result of treating 1 kg of the spray material at 700 ° C., and asbestos is sufficiently decomposed at this temperature. Magnesium silicate Mg ₂ SiO ₄ and magnesium silicate Mg ₃ Si ₄ O ₁₀ in which silicic acid is polymerized ( OH) ₂ and magnesium fluoride MgF ₂ are formed. (H) has shown the analysis result which processed what mixed 1 kg of asbestos spraying materials and 1 kg of slaked lime Ca (OH) ₂ by 1: 1 at 700 degreeC.

As shown in FIG. 8, asbestos is not detected at a decomposition temperature of 700 ° C., but asbestos remains at 600 ° C. Therefore, the decomposition temperature is required to be 700 ° C. or higher, and since the decomposition is performed at 700 ° C., a high temperature exceeding 1000 ° C. is not required unlike the conventional case. 700 ° C. to 800 ° C. is preferable. That is, in the present invention, asbestos and / or an asbestos-containing substance are present together with flon, halon, or sulfur hexafluoride in an atmosphere of superheated steam capable of decomposing flon at about 700 ° C. to 800 ° C. At the same time, asbestos can be decomposed, in which case hydrogen fluoride HF and hydrochloric acid HCl act directly on asbestos and decompose. Moreover, it turns out that decomposition | disassembly is accelerated | stimulated by suppressing superposition | polymerization of silicic acid by adding slaked lime (calcium hydroxide Ca (OH) ₂ ) to the processing furnace 1. FIG. When slaked lime is not added, magnesium silicate different from asbestos is formed. Therefore, in order to decompose asbestos more reliably, it is preferable to add slaked lime. In addition, instead of the slaked lime (calcium hydroxide Ca (OH) ₂ ), limestone (calcium carbonate CaCO ₃ ), quick lime (calcium oxide CaO), gypsum (calcium sulfate CaSO ₄ ), cement (main components are CaO, SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ ) may be added.

FIG. 9 shows the X-ray diffraction after processing using a glass fiber glass similar to asbestos as the material to be decomposed 10 with a flow rate of chlorofluorocarbon of 2 kg / h and a superheated steam flow rate of 1 kg / h as described above. No. 1 is the result of analyzing the glass fiber, but no asbestos was detected. No. 2 is the result of analyzing the glass fiber-containing spray material, and CaCO ₃ is detected as the main component. No. 3 shows an analysis result obtained by treating 1 kg of No. 2 to be decomposed with 1 kg of slaked lime Ca (OH) ₂ at 700 ° C., and CaF ₂ is generated. No. 4 shows the analysis result of the No. 2 decomposition target processed at 800 ° C., and CaSi ₂ is generated. No. 5 shows an analysis result obtained by treating 1 kg of No. 2 to be decomposed with 1 kg of slaked lime Ca (OH) ₂ at 800 ° C. It can be seen from FIG. 9 that the spray glass fiber can be almost disassembled. Discrimination between asbestos and / or asbestos-containing substances and asbestos-like products is difficult to see visually and is difficult to identify without analysis by X-ray diffractometry, etc., making it impossible to separate when mixed at the time of collection close. According to the present invention, even if asbestos-like products are mixed, it can be decomposed without problems, so there is no need to determine whether or not it is an asbestos and / or an asbestos-containing substance and its similar products, and it is extremely practical. There is.

It is considered that the basic decomposition of asbestos proceeds according to the following reaction formula.
_{2Mg 3 Si 2 O 5 (OH} ) 4 = 3Mg 2 SiO 4 + SiO 2 + 4H 2 O ... (1)
_{3Mg 3 Si 2 O 5 (OH} ) 4 + 2CHClF 2 + H 2 O
→ 3Mg ₂ SiO ₄ + 3SiO ₂ + 2MgF ₂ + MgCl ₂ + 2CO ₂ + 6H ₂ O
……… (2)

H ₂ O in the pre-reaction formula will cancel out with 6H ₂ O in the post-formation, but in reality, hydrolysis with superheated steam occurs, and it is considered that decomposition begins by reaction with HF, HCl, I haven't offset it. Decomposition when slaked lime is added is Mg ₃ Si ₂ O ₅ (OH) ₄ + 2CHClF ₂ + 3Ca (OH) ₂ + H ₂ O
→ Mg ₂ SiO ₄ + MgO + SiO ₂ + 2CaF ₂ + CaCl ₂ + 2CO + 7H ₂ O
……… (3)
Or 2Mg ₃ Si ₂ O ₅ (OH) ₄ + 2CHClF ₂ + 3Ca (OH) ₂
→ 3Mg ₂ SiO ₄ + SiO ₂ + 2CaF ₂ + CaCl ₂ + 2CO ₂ + 12H ₂ O
……… (4)
Therefore, when slaked lime is added, it is considered that Mg ₂ SiO ₄ is polymerized to become magnesium silicate Mg ₃ Si ₄ O ₁₀ (OH) ₂ .

The above is an example in which slaked lime (calcium hydroxide Ca (OH) ₂ ) is added, because slaked lime is easy to obtain, stable in the air, and easy to handle because it is a powder. More preferably, quick lime (calcium oxide CaO) is added. Decomposition when quick lime (calcium oxide CaO) is added is as follows.
Mg ₃ Si ₂ O ₅ (OH) ₄ + 2CHClF ₂ + 3CaO + H ₂ O
→ Mg ₂ SiO ₄ + MgO + SiO ₂ + 2CaF ₂ + CaCl ₂ + 2CO + 4H ₂ O
......... (5)
Or 2Mg ₃ Si ₂ O ₅ (OH) ₄ + 2CHClF ₂ + 3CaO
→ 3Mg ₂ SiO ₄ + SiO ₂ + 2CaF ₂ + CaCl ₂ + 2CO ₂ + 9H ₂ O
……… (6)

However, quick lime (calcium oxide CaO), when powdered, absorbs moisture in the air and immediately changes to Ca (OH) ₂ , making it difficult to store and is not powdered. Is required.

Furthermore, when limestone (calcium carbonate CaCO ₃ ) is heated, CaCO ₃ = CaO + CO ₂ (7)
It has the same effect as adding quick lime (calcium oxide CaO). Moreover, when slaked lime (calcium hydroxide Ca (OH) ₂ ) is heated, Ca (OH) ₂ = CaO + H ₂ O (8)
It becomes the same effect as adding quick lime (calcium oxide CaO).

Here, an example of chlorofluorocarbon decomposition will be described below. When the substance to be decomposed is chlorofluorocarbon CFC-12, hydrolysis of the following formula (9) proceeds by reaction with superheated steam.
CCl ₂ F ₂ + 2H ₂ O → CO ₂ + 2HCl + 2HF (9)

Similarly, the hydrolysis of CFC-22 is carried out by the following formulas (10) to (12).
CHClF ₂ + 2H ₂ O → CO ₂ + HCl + 2HF + H ₂ (10)
CHClF ₂ + H ₂ O → HCl + 2HF + CO (11)
4CHClF ₂ + 6H ₂ O → 3CO ₂ + 8HF + 4HCl + CH ₄ (12)
According to the equations (10), (11), and (12), there is a problem that harmful or flammable gases such as H ₂ gas, CO gas, and CH ₄ gas are generated. Then, when air or oxygen is added together with water to cause hydrolytic decomposition, the following equation (13) proceeds.
CHClF ₂ + H ₂ O + 1 / 2O ₂ → CO ₂ + HCl + 2HF (13)
Therefore, carbon monoxide CO is 2CO + O ₂ = 2CO ₂
The hydrogen gas H ₂ is 2H ₂ + O ₂ = 2H ₂ O
And methane gas CH ₄ is CH ₄ + 3O ₂ = CO ₂ + 2H ₂ O
It becomes. Therefore, noxious or flammable gases are detoxified as carbon dioxide or converted to moisture.

  Note that air or oxygen can be supplied during the above-described hydrolysis of flon to promote the decomposition of freon, and further, air or oxygen can be supplied to the exhaust gas decomposition apparatus 13.

Further, the reaction formula when using halon gas (CF ₃ Br) is as follows.
_{2Mg 3 Si 2 O 5 (OH} ) 4 + CBrF 3 + 2Ca (OH) 2
= 3 Mg ₂ SiO ₄ + SiO ₂ + CaF ₂ + CaBrF + CO ₂ + 6H ₂ O
……… (14)
Or Mg ₃ Si ₂ O ₅ (OH) ₄ + CBrF ₃ + 2Ca (OH) ₂
= Mg ₂ SiO ₄ + SiO ₂ + MgO + CaF ₂ + CaBrF + CO ₂ + 4H ₂ O
……… (15)

Furthermore, the reaction formula when sulfur hexafluoride (SF ₆ ) is used is as follows.
Mg ₃ Si ₂ O ₅ (OH) ₄ + SF ₆ + 4Ca (OH) ₂
= Mg ₂ SiO ₄ + SiO ₂ + MgO + 3CaF ₂ + CaSO ₄ + 6H ₂ O
……… (16)

  As described above, the present invention is characterized in that it is possible to easily decompose the material to be decomposed 10 made of asbestos and / or an asbestos-containing substance simultaneously with the decomposition of chlorofluorocarbon, halon, or sulfur hexafluoride. Since the inside is a processing furnace that is not pressurized but is at normal pressure or slightly negative pressure and is not forced to pressurize, even if the processing furnace 1 is damaged, the material 10 to be decomposed is scattered outside the system. There is no fear of doing so. Further, since the heat generation energy generated at the time of chlorofluorocarbon decomposition is effectively used and the decomposition temperature may be in the range of 700 ° C. to 800 ° C., it is relatively low compared with the high temperature of about 1500 ° C. required for conventional melting processing. There is a feature that can be processed. Furthermore, the detoxified decomposition products can be used for landfill disposal in the ground, or used in place of quarry used as various construction aggregates.

  As described above in detail, according to the present invention, not only the decomposition of flon but also the decomposition of asbestos and / or asbestos-containing material simultaneously with the decomposition treatment of flon or halon or sulfur hexafluoride which is a hardly decomposable substance. Asbestos can be decomposed at high efficiency and at low cost, so it is difficult to decompose chlorofluorocarbon or halon or sulfur hexafluoride, which is a non-decomposable substance, as well as conventional non-combustible construction materials, electrical products, automobiles and households. It can be widely used when decomposing asbestos and / or an asbestos-containing substance generally used widely for articles and other uses. Even if only asbestos is considered, the decomposed product can be reused as crushed stone and can be processed in a large amount in a short time with good decomposition efficiency. Because the reaction time is short and the atmosphere is negative or slightly negative, the material to be decomposed does not scatter to the outside, and continuous operation is possible. Mixing is a powder and a solid, so it is put into a processing furnace. It is sufficient to stir with a screw.

1 is a system diagram schematically showing a first embodiment of the present invention. The flowchart of 1st Embodiment. The system diagram which shows 2nd Embodiment of this invention roughly. The flowchart of 2nd Embodiment. The system diagram which shows schematically 3rd Embodiment of this invention. The flowchart of 3rd Embodiment. The diagram which analyzed the processing result by this invention by X-ray diffraction. A diagram in which the flow rate of CFC gas and the flow rate of superheated steam are processed by changing the temperature in the processing furnace and analyzed by X-ray diffraction. The diagram which processed using the spray material glass fiber as a to-be-decomposed thing, and analyzed by X-ray diffraction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Batch type processing furnace 2, 14 ... Heater 3 ... Freon gas inlet 4,15 ... Superheated steam inlet 5 ... Stirrer 6 ... Stirrer blade 7 ... Exhaust gas cleaner 8 ... Filter 9 ... Blower 10 ... Decomposition processing object 11 ... Slaked lime inlet 12 ... Processed material outlet 13 ... Exhaust gas decomposition device 17 ... Processed material tank 18 ... Motor 19 ... Screw 23 ... Processed material inlet

Claims (12)

A method for decomposing asbestos, comprising decomposing asbestos and / or an asbestos-containing substance as an object to be decomposed using heat generated during decomposition of CFC using superheated steam at 700 ° C to 800 ° C. Asbestos and / or asbestos-containing material as a material to be decomposed is retained in a processing furnace together with superheated steam at 700 ° C. to 800 ° C. and chlorofluorocarbon for a certain period of time to decompose the material to be decomposed together with chlorofluorocarbon. Asbestos decomposition method. Asbestos and / or asbestos-containing material as a material to be decomposed is decomposed together with chlorofluorocarbon by allowing a predetermined reaction time to elapse in a processing furnace heated to a predetermined temperature together with superheated steam and chlorofluorocarbon of 700 ° C to 800 ° C. A method for decomposing asbestos, comprising decomposing a processed product. Asbestos and / or an asbestos-containing substance as a material to be decomposed is put into a processing furnace heated to a predetermined temperature, and superheated steam and Freon gas at 700 ° C. to 800 ° C. are passed through the processing furnace for a predetermined reaction time. The decomposition | disassembly processing method of asbestos characterized by decomposing | disassembling a to-be-decomposed processing object with a chlorofluorocarbon. The method for decomposing asbestos according to claim 2, 3 or 4 , wherein the gas discharged from the processing furnace is guided to an exhaust gas scrubber, cleaned with a cleaning liquid, and then sucked with a blower through a filter and diffused outside the system. The gas discharged from the processing furnace is guided to an exhaust gas decomposition apparatus heated to a predetermined temperature, and superheated steam is injected into the exhaust gas decomposition apparatus for reaction, and the gas discharged from the exhaust gas decomposition apparatus is guided to an exhaust gas scrubber. 5. The method for decomposing asbestos according to claim 2, 3 or 4 , wherein the asbestos is washed with a washing liquid and then sucked with a blower through a filter and diffused outside the system. The method for decomposing asbestos according to claim 2, 3 , 4 , 5, or 6 , wherein a reaction accelerator is introduced into the treatment furnace together with chlorofluorocarbon gas and superheated steam and the reaction is carried out for a predetermined time.   The method for decomposing asbestos according to claim 7, wherein one or more selected from limestone, quicklime, slaked lime, gypsum, and cement are added as a reaction accelerator and reacted for a predetermined time. The method for decomposing asbestos according to claim 2, 3 , 4 , 5 , 6, 7 or 8 , wherein the treatment furnace is heated in a temperature range of 700C to 800C. The asbestos decomposition processing method according to claim 2, 3 , 4 , 5 , 6 , 7 , 8 or 9 , wherein a screw to be rotationally driven by a motor is disposed in the processing furnace to convey the decomposition target.   The method for decomposing asbestos according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein halon is used instead of freon.   The method for decomposing asbestos according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein sulfur hexafluoride is used in place of chlorofluorocarbon.

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