JP2012020272A - Asbestos-based waste, and detoxifying treatment method and dedicated melting furnace for pcb - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: it is necessary to implement detoxifying treatment without generating asbestos dust and treating a trace quantity of PCB at low cost because a large amount of treatment cost is required for treatment of asbestos and handling of PCB and further an environmental problem as well as a danger occurs in handling due to the generation of dust or toxicity of PCB.SOLUTION: A detoxifying treatment method for waste under special control includes a process of impregnating asbestos-based waste with PCB, and a process of blending the asbestos-based waste impregnated with PCB with a thermite pill, and performing heat melting and vitrification. A blending ratio of the asbestos-based waste impregnated with PCB to the thermite agent is 100:(5-30) in weight ratio.

Description

The present invention relates to a method for melting and detoxifying asbestos waste and PCB or waste containing asbestos impregnated with PCB.

Although the prior art focuses on lowering the melting temperature of asbestos, it still has the disadvantage of high energy costs for melting.

Since asbestos is carcinogenic and harmful to the human body, there have been many attempts to make asbestos harmless by melting and vitrifying it.
For example, Japanese Patent Application Laid-Open No. 2008-272535 describes that glass frit and melting aid (soda ash, borax) are added to asbestos and melted at a lower melting temperature.
On the other hand, a method that does not require high-temperature heating, for example, a method in which asbestos is dissolved with hydrochloric acid or sulfuric acid, a processing method in which hydraulic cements are added to asbestos and solidified, a sodium silicate aqueous solution or a synthetic resin emulsion, etc. There is also a method of coating the surface.

The prior art focuses on lowering the energy cost by lowering the melting temperature of asbestos or heating it, but in any method, the process of mixing the treated product containing asbestos and the treatment agent is not necessary. In this process, it is inevitable that asbestos dust is generated and scattered in the surrounding environment, and there is a possibility that new waste is generated separately. On the other hand, various methods have been devised to prevent the scattering of harmful dust, but the present invention can be applied to a PCB solution that is the same harmful substance, or a PCB solution that has increased fluidity by heating a PCB adhering substance. Innovative technology capable of treating two types of harmful substances at once by impregnating asbestos and preventing the asbestos from scattering, and by detoxifying the PCB using the melting temperature range of asbestos It is.

JP 2008-272535 A

The present invention has been made in view of such problems. The purpose of the present invention is to perform asbestos impregnation in a PCB solution in advance when heat-melting and detoxifying asbestos, and then heat-melting the asbestos dust. It is to provide a novel processing technique that can prevent the generation of molten glass and can be made into molten glass or molten slag at low cost.

Means to solve the problem

As a result of conducting experiments and earnest studies on the above issues, the following knowledge was obtained.
In other words, the asbestos that was peeled and collected was impregnated in the PCB solution, or the PCB solution was mechanically sprayed and applied to the asbestos, or the waste PCB was heated using the waste heat of heat while the asbestos was transported into the melting furnace. It was found that dust was not generated when the obtained PCB solution was impregnated with asbestos and fed into a melting furnace. In addition, even if heated in the melting furnace, once it entered the melting furnace, the airflow in the melting furnace was naturally in the melting environment, so it turned out that it would not become dust again and be discharged outside the furnace. .

In order to melt asbestos waste, it was thought that a small cutting and stirring operation was necessary as pre-treatment, but if asbestos waste was impregnated in a PCB solution and sent to the melting furnace, dust may not be generated. As a result, a water tank directly connected with cooling water or a water tank with a water tank can be provided below the outlet of the melting furnace, and the molten material flowing out of the melting furnace is dropped directly into the water. Since the above molten materials are rapidly cooled to 100 ° C. or less at once, the hot water repels greatly in the water and becomes a granulated slag having a diameter of about 2 to 4 mm, and there is a solidified slag that can be used as an aggregate. It was also found that it was generated.

Just before the PCB-impregnated asbestos waste is put into the melting furnace, when the thermite pills are mixed and heated and melted in the melting furnace, the thermite reaction is simultaneously generated under the heating burner, and the thermite reaction heat is generated. Explosive shock waves are also generated and the mixture is disturbed, and the temperature in the ultra-high temperature range reaches the details of the object to be melted. That is, it is common knowledge that the heating in the melting furnace is the surface layer heating of the object to be melted, and only the surface layer is melted, which is only surface melting. In the case of a surface melting furnace using burner heating as a heat source, or in the case of a coke bed method using coke as a heat source, the furnace of the melting furnace is heated. Although the internal temperature is usually 1450 ° C. to 1550 ° C. even if it is usually high, it has been found that the melting environment of 1700 ° C., which is the melting point of asbestos, is sufficiently formed by the addition of thermite pills.

  Naturally, the melting temperature of the object to be melted per hour is greatly increased due to the high melting temperature, and the treatment time is also fast, and the addition of thermite agent increases the melting amount by 130 to 180% compared to a normal melting furnace. .

The mixing ratio (weight ratio) of the thermit agent is preferably in the range of 5 to 40 for the thermit agent with respect to the PCB-impregnated asbestos 100. Exceeding the upper limit is not preferable because the viscosity of the molten glass increases and the fluidity deteriorates due to the basicity. Further, when the addition of the thermite agent is not more than the lower limit, there is almost no difference from the case of the material to be melted alone, so that the thermite effect cannot be expected.

A thermite agent is a mixture of a raw material containing an aluminum component and a raw material containing an iron oxide component. The mixing ratio is a ratio of 3 iron oxides to aluminum 1, and the raw material containing an aluminum component is a waste aluminum for beverages. Wastes containing aluminum components such as aluminum residue ash (commonly called aluminum dross) generated during remelting of cans and aluminum bullion are effective, but are not limited thereto.

Raw materials containing iron oxide components are general metal scrap such as iron scrap and iron rust, converter dust generated in the steel industry, dust collection ash such as blast furnace dust, and also by-products when producing magnetic iron oxide Iron oxide sludge generated as a slab, red mud when aluminum hydroxide is produced from bauxite, or red mud from residual soil extracted from red mud imported from the south, etc. are effective, but are not limited to this. It is not a thing. These raw materials may be used as they are, or two or more different starting materials may be appropriately mixed and used.

As mentioned above, when the aluminum-containing raw material is a crushed piece of an aluminum can, the one mixed with the iron oxide-containing raw material is pressed into a plate and divided into appropriate sizes and mixed and dispersed in the incineration ash You may let them. The thickness of the crimping piece is preferably about 3 to 6 mm and about 5 to 30 in length. An adhesive component remains in the pressure-bonded piece obtained by evaporating the moisture of the aluminum can, and appropriate strength is exhibited. The size of the crushed pieces of the waste aluminum can may be such that the crushed pieces are crushed into small pieces of about 5 to 10 mm by a cutting machine and then secondarily crushed to 1 to 2 mm or less.

When using iron oxide sludge produced as a by-product during the production of magnetic iron oxide as the iron oxide-containing raw material, the water content may be dried to about 5 to 1% by sun drying or the like. In order to further improve the mixing with the aluminum raw material, the lump is preferably finely pulverized.

The aluminum content in the thermite reaction composition mainly comprising an aluminum-containing raw material and an iron oxide-containing raw material is preferably 5% or more. If it is less than 5%, the thermite exothermic reaction does not occur, which is not preferable. The mixing ratio of aluminum and iron oxide is preferably a ratio of iron oxide content of 2.5 to 3.0 with respect to aluminum content of 1, 3 to 12% by weight of titanium oxide, and manganese oxide of 1 to 3 in the mixture. It is preferable to make it contain by weight%.

When titanium oxide and manganese oxide are already contained in the aluminum raw material and iron oxide raw material, after adding the aluminum raw material and iron oxide raw material, a shortage of titanium oxide and manganese oxide may be newly added.
As a method of adding titanium oxide and manganese oxide, titanium oxide and manganese oxide itself may be added, or those containing titanium oxide and a manganese oxide component may be added. It is also effective to add waste particles containing titanium oxide and manganese oxide.

If the ratio of the aluminum-containing raw material and the iron oxide-containing raw material exceeds the upper limit, the iron oxide becomes excessive and the thermite exothermic reaction does not occur, which is not preferable. On the other hand, if it is less than the lower limit, the amount of aluminum becomes excessive and aluminum remains in the reaction product, which is not preferable.

If the titanium oxide content is less than the lower limit, the thermite reaction product has a high viscosity, so that the meltability becomes poor and continuous operation becomes impossible. Further, even if the content exceeds the upper limit, no further improvement effect of the meltability can be expected. About the mixing method of these compositions, for example, it may be mixed using a normal stirring mixer such as a fret mill, a high speed mixer, a mixer, etc., and there is a special limitation on the addition and mixing method of titanium oxide, manganese oxide and the like. There is no reason.

The thermit agent is preferably formed into granules, pellets (granulated products) or pills. Although there is a method of solidifying with water, since a thin oxide film is formed on the surface of aluminum by the hydration reaction of aluminum, deterioration of aluminum is natural, but importantly, the formation of the aluminum film is a thermite reaction, This is a redox reaction that occurs in the surface contact state between the iron oxide particles and the aluminum powder particles, and is a so-called heating interfacial reaction between both contact surfaces.

There is also a method of bagging both, but before the thermite reaction takes place in the melting furnace, the oxidation reaction (combustion) of the paper or resin-based bag material as the bag material precedes, As a result, diffusion of the target aluminum fine powder and iron oxide fine powder occurs rapidly, and the true target thermite agent effect, that is, the redox reaction is rapidly inhibited.

When the thermite agent is made into pills, granules, or granulated, there is no risk of bag breakage compared to bag-like powder, and because the mixing density of both is high, the propagation speed of combustion heat is high, and a higher exothermic effect is obtained. It is done. As the granule or granulation molding method, dry molding is preferred because the aluminum component constituting the composition easily reacts with moisture. As for the dry molding method, high-pressure molding using a briquette machine or an adhesive inorganic binder may be added, but in the present invention, molding can be easily performed using viscous konjac powder.

The invention's effect

As a result, PCB-impregnated asbestos can be melted at low cost, and by adding thermite pills, the processing capacity is increased by 130% to 180%, and the melting furnace can be started and shut down in 1.5 to 2 hours. It became. In particular, it is easy to start melting, and the fact that melting is possible in 1.5 to 2 hours after ignition of the burner makes intermittent operation free, and continuous operation is a revolutionary technology in the common melting world. In addition, asbestos needle-like crystals disappear completely and become harmless by vitrification by melting, and at the same time, PCB is completely burned down by heat treatment, and the vitrified melt shows no elution of heavy metals, It was expected that it could be effectively used as a secondary product for civil engineering.

The following is an embodiment of the present invention, in which PCB uses waste transformer residue, and asbestos waste material used building waste containing asbestos. The present embodiment is specifically described for better understanding of the gist of the invention, and the present invention is not limited to this.

Example 1
The ground asbestos waste impregnated with PCB was mixed and stirred in a stainless steel stirrer. There was no dust generation and a soft mud was obtained.

Thermite reactant pill pelletized aluminum raw material: Powder of aluminum ash (aluminum dross) generated during remelting of aluminum ingot was used.
Iron oxide component: The red mud when aluminum hydroxide was produced from bauxite was dried and used as it was.
Auxiliary raw materials: Titanium oxide and manganese oxide wastes were used.
The above aluminum raw material, iron oxide component and auxiliary raw material are mixed in the following component composition (wt%), mixed with 3% konjac powder (glue), and 8mm in diameter and 10-20mm in length with a pelletizer. The size of the pellet was made.
Component composition of thermite reactant Aluminum component: 18%
Iron oxide component: 40%
Titanium oxide: 5%
Manganese oxide: 2%

The above PCB impregnated asbestos pulverized pellets and thermite reactant pellets were mixed at a ratio of 100: 30, and a melt test was conducted in a burner melting furnace (surface melting furnace).
FIG. 1 is an explanatory diagram of the burner melting furnace used in this example.
In the figure, reference numeral 3 denotes a raw material to be melted (asbestos waste material). The PCB-impregnated waste 1 is taken out by heating the waste heat 14 of the melting furnace 5 to increase the meltability of the PCB solution. It is the state which pours into.

The molten raw material 3 is pushed onto the inclined hearth 12 of the melting furnace 5 by the pusher 8.
The molten raw material 3 pushed into the furnace flows down from the inclined hearth 12 to the lower water tank 10 through the gate 13 while being melted, and is cooled at once with cooling water to become granulated slag.
Heavy oil A was used as the fuel for the burner.

If only asbestos is put into a burner melting furnace and heated, the fine powder of asbestos will be blown off by the burner flame, dust may be scattered inside the furnace, and it may leak out of the furnace together with exhaust heat and exhaust gas. By impregnating the PCB, the asbestos was not blown away by the burner flame, could be heated under the condition of the furnace, and no dust leaked out of the furnace.

When only asbestos is melted in a burner melting furnace, the theoretical value requires a melting point of 1700 ° C. of asbestos, but the melting began at around 1350 ° C. due to the addition of the thermite agent. On the other hand, when 120 kg of PCB-impregnated pulverized asbestos (PCB 20 kg asbestos pure 100 kg) is mixed with 20 kg of thermite pills and heated with a burner, the heating temperature of the burner is 1350 ° C. It only took time. However, since black smoke was generated for the first time, smooth combustion and white reaction conditions can be confirmed by adding a little air including oxygen from the oxygen cylinder, and a temperature range of 2000 ° C or higher can be visually observed during the thermite reaction. did it. In general, enormous energy is required to convert so-called substances that change from solid to liquid, but once a hot water puddle is created in the hearth by the thermite reaction, PCB-impregnated asbestos pulverized and discarded into the puddle. The thing liquefied without bitterness.

The demonstration results of this technology show that dust generation can be prevented even during the melting process, the temperature rises in a short time by the thermite reaction, a smooth flow of hot water can be confirmed, and by impregnating PCB, dust generation is also possible. It was found that it can be processed at an extremely low cost economically.
Further, no asbestos needle-like crystals were observed in the granulated slag after melting, and it was completely vitrified and rendered harmless.

As described in detail above, the present invention does not generate asbestos dust by impregnating PCB, and can be completely harmlessly melted at low cost without fear of pollution. It enables safe and large-scale processing, and will make a great contribution to the vein industry society in the future.

FIG. 1 is an explanatory view of a surface melting furnace used in Example 1 of the present invention.

1. Trace PCB impregnation waste 2. Heated PCB liquid 3. Asbestos waste (asbestos)
4. Thermite pill 5, melting furnace 6, hot water reservoir 7, heating burner 8, waste pusher 9, hot water pusher 10, slag cooling device 11, granulated slag 12, inclined hearth 13, tap gate 14, melting Furnace exhaust heat

Claims (8)

A step of roughly crushing asbestos waste, a step of impregnating the asbestos waste with a PCB solution heated and fluidized in advance, and a PCB-impregnated asbestos waste and a trace amount of PCB-attached waste, A detoxification treatment method for asbestos-based waste and PCB, comprising a step of mixing and adding a thermite agent to heat and melt and vitrify in the step of charging into a melting furnace. The asbestos waste and PCB detoxification treatment according to claim 1, wherein a mixing ratio of the PCB-impregnated asbestos waste and the thermite agent is 100: (5 to 30) by weight. Method. The asbestos-based waste according to claim 1 or 2, wherein one or two or more kinds in the group of (volcanic ash, borax, crushed glass) are mixed with the PCB-impregnated asbestos-based waste. PCB detoxification method. In a melting furnace for treating inorganic waste. The inclination angle of the entire hearth is 15 to 35 degrees, a part of the inclined floor surface is cut out, and the angle of the notch is 0 to 14 degrees. A melting furnace characterized by having a hearth with a hot water pool for molten material. A method for treating hazardous waste, in which general incineration ash, industrial waste incineration ash, or fly ash and PCB are mixed and melted for the purpose of preventing ash scattering and PCB overflow. A melting furnace provided with a pusher dedicated to a sump in the melting furnace according to claim 6. When PCB material is insufficient in the process of impregnating PCB with asbestos waste for the purpose of preventing scattering, water glass is added as an extender as a substitute for PCB, or asbestos waste is impregnated into water glass and melted. The detoxification processing method of asbestos-based waste and PCB of Claims 1-3 to perform. In the asbestos-based waste and PCB detoxification processing type melting furnace according to claim 1, by using the heat discharged from the melting furnace, the fluidity of the PCB adhering to the PCB adhering substance is increased and the PCB solution can be easily recovered. At the same time, the asbestos-based waste and the PCB detoxification treatment method according to claim 1 equipped with a function of detoxifying a small amount of PCB-attached waste PCB by exhaust heat.

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