JP2002168419A - Dust incineration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust incineration method for preventing abnormal temperature increase in an incineration furnace and preventing damage, and at the same time inhibiting the generation of a harmful exhaust gas, and adsorbing and fixing heavy metal ions in residual ash of the incineration. SOLUTION: Dust is incinerated in the incineration furnace under the presence of aluminum hydroxide such as gibbsite, bayerite, boehmite, nordstrandite or the like, and/or transition alumina expressed by a general expression Al2O3 having a crystal form mainly of γ, ρ, θ, χ, δ, κ or the like and having a BET specific surface area of 30 m2/g or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a dust incineration method using an incinerator. For details, suppress abnormal heat generation in the incinerator, suppress emission of toxic gas components such as dioxin generated during incineration from the incinerator, and furthermore, when heavy metal ions etc. are present in the combustion ash The present invention relates to a dust incineration method having an effect of suppressing the leakage of heavy metal ions due to rainwater or the like and having excellent environmental protection.

[0002]

2. Description of the Related Art In recent years, the amount of household dust and commercial dust has been increasing in Japan along with changes in lifestyles and rising income levels. Furthermore, the type of dust has also changed, and at present the dust of resin products is increasing due to the increase in petroleum-related products. Usually, after collecting various valuable components from the viewpoint of resource saving, resource recycling, and environmental protection, these dusts are separated into non-combustible dust and combustible dust, and are subjected to landfill and incineration.

[0003] By the way, the combustible dust usually emitted from ordinary households contains a large amount of combustible resin, and the following problems are presently occurring. In other words, the thermoplastic resin, which is the raw material of the dust bag, generates a large amount of heat during incineration and the temperature inside the incinerator rises abnormally, causing severe damage to the incinerator materials. Vinyl chloride, vinylidene chloride (wrapping for food packaging) When burning chlorine-containing resin such as toxic dioxin may be released to the atmosphere, and when incineration residual ash is landfilled, heavy metal ions contained in the ash may cause rainwater, etc. May be dissolved and leaked.

In order to cope with such problems, the temperature in the incinerator is increased by spraying water into the incinerator to prevent the temperature from increasing in the incinerator or by filling calcium carbonate in a dust bag for collecting combustible dust. A method of reducing the combustion heat of the resin itself by using a resin that has been used has been adopted. On the other hand, studies on the control of dioxin emission into the atmosphere are being conducted from both directions of prevention of dioxin generation and adsorption and recovery. Measures to prevent the generation of dioxin precursors include controlling the operation of incinerators in accordance with the guidelines for operation of incinerators set by the Environment Agency, and introducing new types of furnaces to completely combust combustion products and prevent the generation of dioxin precursors. Is underway. Further, as the latter adsorption and recovery measure, a method of putting activated carbon or the like into a bag filter portion of a dust collector has been implemented. As a measure for preventing leakage of harmful substances at the time of landfill, a method of insolubilizing a contained harmful substance and then solidifying it with cement or the like and disposing it in a landfill has been adopted. However, these methods have to be individually dealt with according to each purpose, such as protection of refractory materials constituting the furnace, installation and modification of equipment to prevent dioxin scattering, and measures to prevent heavy metal ion leakage from incineration residual ash. First of all, enormous processing costs are required to take all measures, and it has been desired to develop a method that is inexpensive and effective for a plurality of items.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to prevent abnormal temperature rise of an incinerator during operation of the incinerator and to prevent harmful exhaust gas such as dioxin from scattering into the atmosphere while suppressing damage to the furnace material. It is an object of the present invention to provide a dust incineration method that suppresses harmful substances contained in incineration residual ash and exerts an effect of preventing leakage of harmful substances contained in the incineration landfill.

In view of such circumstances, the present inventors have made intensive studies to achieve the above object, and as a result, when burning dust in an incinerator, an extremely simple method of simply allowing an aluminum compound to coexist with dust to be burned. It has been found that all the above objects can be satisfied by the method, and the present invention has been completed.

[0007]

That is, the present invention relates to a method for burning dust in an incinerator in the presence of aluminum hydroxide and / or transition alumina having a BET specific surface area of 30 m ² / g or more. The present invention provides a dust incineration method characterized by burning methane.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The greatest feature of the present invention is that when dust is incinerated in an incinerator,
Aluminum hydroxide and / or BET specific surface area is 30m
² / g or more of transition alumina. The aluminum hydroxide emits water of crystallization due to the heat of combustion of dust in the incinerator. Since the release of water of crystallization is an endothermic reaction, the furnace temperature is lowered. When aluminum hydroxide is calcined at a specific temperature, crystal transition occurs, and the aluminum hydroxide is transformed into transition alumina (activated alumina) having a high BET specific surface area, which has a very high gas adsorption ability and a high metal ion adsorption ability. According to the present invention, when incinerating dust in an incinerator, an aluminum hydroxide and / or a transition alumina having a BET specific surface area of 30 m ² / g or more are present in the dust, and the dust is incinerated at a specific temperature, whereby the furnace is constructed. Aluminum hydroxide added to dust during incineration is transferred to transition alumina with a high BET specific surface area without damaging furnace construction materials such as refractory materials and joints, and adsorbs HCl and dioxin generated during incineration. At the same time, when the residual ash is landfilled, it has the effect of adsorbing heavy metal ions contained in the residual ash and has a leakage preventing effect, and when transition alumina having a BET specific surface area of 30 m ² / g or more is present, the same HC
They have found an effect of adsorbing l and dioxin and an effect of adsorbing heavy metal ions to prevent leakage.

The type of aluminum hydroxide used in the present invention may be any one having water of crystallization such as gibbsite, bayerite, boehmite, nortostrandite and the like. However, among these, gibbsite is preferably used because it is produced in large quantities as a raw material for alumina and aluminum by the Bayer method and can be easily obtained at low cost. Further, sludge containing aluminum hydroxide used for wastewater treatment, aluminum hydroxide recovered from an alkali solution used for aluminum surface treatment of an aluminum sash or the like can also be used.

The method for causing the aluminum hydroxide of the present invention to exist in the furnace is not particularly limited, but the following method is usually used. For example, a method of mixing waste and aluminum hydroxide to be incinerated in advance and adding them to the incinerator, a method of separately adding aluminum hydroxide directly into the furnace while controlling the temperature in the incinerator separately from the waste,
A resin molded product obtained by kneading aluminum hydroxide in a resin [for example, a shopping bag (shopping bag) for a supermarket, etc.,
Or a commercially available dust bag or a combustible dust collection bag distributed by a local government, etc. However, these must be separately manufactured in advance. And burning it together with other dust.

The BET specific surface area used in the present invention is about 30 m
The transition alumina of ² g / g or more, preferably about 50 m ² / g or more, more preferably about 80 m ² / g or more may be any known one, and is generally commercially available as activated alumina. Is represented by a general formula Al ₂ O ₃ mainly composed of γ, ρ, θ, χ, δ, κ and the like.
When the BET specific surface area is less than the above range, even if these transition aluminas are present in the incinerator during the combustion of dust, the effect of suppressing exhaust gas, the effect of adsorbing, and the effect of preventing elution of heavy metal ions are low. Although there is no limitation on the method of allowing these substances to be present in these furnaces, for example, a method in which dust to be incinerated and transition alumina are mixed in advance and added to the incinerator, transition alumina while controlling the temperature in the incinerator separately from the dust, Separately in a furnace, a resin molded product obtained by kneading transition alumina in a resin (for example, a shopping bag (plastic bag) for a supermarket or the like, or a commercially available dust bag or combustible dust collection distributed by a local government) Bags, etc. However, these must be separately manufactured in advance. And burning it together with other dust.

The amount of aluminum hydroxide relative to dust is usually about 0.001% to about 40% by weight, preferably about 0.01% to about 30% by weight, and a BET specific surface area of 30% by weight.
The amount of transition alumina above m ² / g is usually about 0.001
% To about 30% by weight, preferably about 0.01% to
About 20% by weight. When the amount of aluminum hydroxide and / or the transition alumina having a BET specific surface area of 30 m ² / g or more at the time of incineration is smaller than the above range, the temperature control effect is obtained.
When the heavy metal ion adsorption effect and the like are low and the abundance exceeds the above range, the combustion temperature reduction effect, the effect of suppressing exhaust gas due to chlorine gas, the effect of adsorption, and the effect of adsorbing heavy metal ions are increased. Since the incineration ash increases, the upper limit is determined by the order of demand.

[0013] The type of incinerator used in the present invention is not particularly limited, but a stoker type incinerator, a fluidized bed type incinerator, or a stalker type incinerator generally used in local governments or establishments equipped with incineration facilities, etc. Applicable to rotary kilns and the like.

In the practice of the present invention, the incineration conditions are not unique according to the incinerator used, the incineration temperature, the incineration time, the amount of dust put into the incinerator, the type of dust, etc. Is about 500 ° C to about 1100 ° C, preferably about 500 ° C to about 1000 ° C, more preferably about 600 ° C to
About 900 ° C. When the temperature in the incinerator is lower than 500 ° C., the burning rate in the incinerator becomes slow, and it takes a longer time to incinerate dust than during normal operation, which is not practical. About 1100 ° C
If the temperature exceeds 1100 ° C., there is a risk of damaging the furnace, and the activity of the activated alumina crystallized from the added aluminum hydroxide is reduced. Crystal dislocation occurs to alumina and the specific surface area decreases. The incineration time is such that aluminum hydroxide after incineration is usually in the form of crystals, χ-alumina, γ-alumina, θ-alumina, η-alumina, δ
-BET with transition alumina such as alumina and κ-alumina
The specific surface area of about 30 m ² / g or more, preferably about 50 m ²
/ G or more of transition alumina.

Further, in the present invention, aluminum hydroxide present in the incinerator is crystallized from aluminum hydroxide to transition alumina by heat of incineration of dust, and exhibits effects such as gas absorption, adsorption, and decomposition. Normally, even in continuous incineration or intermittent use in a commercial dust incinerator, since incineration residual ash always remains in the furnace, there will be transition alumina crystallized from the above-described aluminum hydroxide, It has the effect of removing harmful components in the generated exhaust gas.However, when completely removing incineration ash from the furnace, add activated alumina to the furnace as necessary, It can also be used as an effect-replacement material until the aluminum hydroxide to be transferred to activated alumina. Of course, it is also possible to use a mixture of aluminum hydroxide and activated alumina.

Furthermore, in the present invention, aluminum hydroxide is
0.0% of solid fuel produced by compression molding combustible dust
01 wt% to 40 wt%, preferably 0.01 wt% to
30% by weight, BET specific surface area is 30m ²
/ G or more of transition alumina is 0.001% by weight or more.
It may be present in incinerators and combustion furnaces at a content of 30% by weight, preferably 0.01% to 20% by weight. Solid fuel (RDF) produced by compression molding of dust and the like is also a method that has recently attracted attention as a measure to suppress the amount of dioxin generated from small incinerators.

[0017]

According to the present invention described in detail above, the aluminum hydroxide and / or BET specific surface area during dust incineration is 3%.
A very simple method of coexisting 0 m ² / g or more of transition alumina prevents abnormal temperature rise in the incinerator, suppresses furnace damage, and discharges harmful exhaust gas such as dioxin caused by chlorine gas etc. It can control and prevent harmful substances contained in the incineration ash from leaking at landfill sites, and its industrial utility value is extremely large as well as environmental hygiene.

[0018]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Example 1 100 parts by weight of a high-density polyethylene film containing 30% by weight of aluminum hydroxide powder (center particle diameter 8 μm, manufactured by Sumitomo Chemical Co., Ltd.), and high-density polyethylene containing no aluminum hydroxide powder at all Film 10
0 parts by weight were burned, and the calorific value was measured using a cylinder calorimeter. As a result, the heat of combustion of the high-density polyethylene film containing the aluminum hydroxide powder was 7791 c
al / g, and those not containing were 11,200 cal / g.

Example 2 Assuming continuous incineration of dust on a commercial basis, aluminum hydroxide powder (C-31 manufactured by Sumitomo Chemical Co., Ltd.) was previously burned in an electric furnace together with polyethylene film, wood chips and cardboard, The incineration ash was obtained. This incineration ash is substantially activated alumina and has a BET specific surface area of 101.
m ² / g. 1.5 mg of the above incinerated residue ash, 1.5 mg of aluminum hydroxide (C-31), 1 vinyl chloride powder
0 mg was put into a plastic combustion tester PCT (manufactured by Sugiyama Genryiki) and burned under the conditions of a combustion temperature of 750 ° C., an air supply rate of 0.5 L / min, and a combustion time of 10 minutes. The generated HCl gas conforms to JIS-K7217 and is 20 mM
After absorption with sodium carbonate, it was quantified by silver nitrate titration. As a result, the detected amount of HCl was 4.3 mg, and 5.1 mg when aluminum hydroxide and activated alumina were not added.

Example 3 Assuming continuous incineration of dust on a commercial basis, the center particle diameter was 3 μm.
A high-density polyethylene film containing 30% by weight of aluminum hydroxide powder (manufactured by Sumitomo Chemical Co., Ltd.) was burned together with wood pieces and cardboard in an electric furnace to obtain incineration residual ash. This incineration ash was substantially activated alumina and had a BET specific surface area of 114 m ² / g. A glass column for gas chromatography (outer diameter 5 mm, inner diameter 3 mm, length 50 cm) was filled with 0.5 g of the above incinerated residue ash. The glass column was set on a gas chromatograph, a carrier gas (nitrogen) was flowed while maintaining the temperature at 200 ° C., and 0.2 ml of a 4.8 μg / ml dioxin / n-hexane solution was injected in four portions with a 50 μl syringe for 2 minutes. The dioxin / n-hexane solution used was 1,3,6,8, -tetrachlorodibenzodioxin, 1,2,4,7,8, -pentachlorodibenzodioxin, 1,2,6,7, -tetrachloro It contains 1.2 μg / μl of dibenzofuran and 1,3,4,7,8-pentachlorodibenzofuran, respectively. After injecting dioxin, the carrier gas was kept flowing for 5 minutes, then the heater and the carrier gas were stopped, and the apparatus was rapidly cooled. After cooling, the incineration ash in the column was taken out, and the amount of dioxin contained in the incineration ash was analyzed.
The analysis used a method based on the “Manual for Standard Measurement and Analysis of Dioxins in Waste Disposal (February 1997)” prepared by the Environment Improvement Section of the Water Supply Environment Department of the Ministry of Health and Welfare. Table 1 shows the results.

Example 4 The incineration ash used in Example 2 was replaced with 0.5 g.
Using a commercially available activated alumina having a BET specific surface area of 170 m ² / g, a dioxin adsorption test was conducted in the same manner as in Example 3. Table 1 shows the results.

Comparative Example 1 A dioxin adsorption test was carried out in the same manner as in Example 5 except that the incineration residue ash used in Example 3 was replaced with the incineration residue ash prepared in the following procedure. Table 1 shows the results. (Adjustment of incineration residual ash used in Comparative Example 1) A high-density polyethylene film containing 30% by weight of calcium carbonate was burned together with wood pieces and cardboard in an electric furnace.
The incineration ash was obtained. The main component of this incineration residual ash was calcium carbonate, and its BET specific surface area was 4 m ² / g. )

Comparative Example 2 A dioxin adsorption test was carried out in the same manner as in Example 3 except that activated carbon having a BET specific surface area of 1200 m ² / g was used instead of the incineration residue ash used in Example 3. Table 1 shows the results.

[0025]

[Table 1]

Example 5 A mechanical batch furnace with an incineration capacity of 40 t / day (model: Ebara B)
Dust incinerator, manufactured by Ebara Infilco Co., Ltd.), gas cooling room, incinerator equipped with multi-cyclone, 25 tons of general household waste, 250 kg of aluminum hydroxide in the incinerator so that aluminum hydroxide is evenly dispersed in the waste It was charged and burned at about 7 hours. After the combustion was completed, 70 g of the collected fly ash was packed in a glass column having an inner diameter of 25 mm and a length of 600 mm with a shut-off valve at the bottom, and 200 ml of deionized water was poured from above with the shut-off valve closed. 24
After leaving for a period of time, the shut-off valve was opened, the extracted water was taken out from the bottom over 12 hours, and the concentration of heavy metal ions in the extract was measured with an atomic absorption spectrophotometer. The heavy metal ion concentration in the test ash was calculated from the result of the fluorescent X-ray analysis. The extraction ratio of each heavy metal ion was calculated from the obtained heavy metal ion concentration in the ash and the heavy metal ion concentration in the extract using the following formula. Table 2 shows the results. Extraction rate (%) = [(amount of test deionized water x content of heavy metal ion in extract) / (amount of test ash x content of heavy metal ion in ash)] x 100

Comparative Example 3 Waste was burned in the same manner as in Example 5, except that aluminum hydroxide was not added, and heavy metal ions were extracted in the same manner as in Example 5 using the recovered fly ash. Was.
Table 2 shows the results. The same alumina concentration in fly ash as that used in Example 5 and Comparative Example 3 was measured by a fluorescent X-ray measuring apparatus, and it was found that Example 5 was increased by 5% by weight as compared with Comparative Example 3.

[0028]

[Table 2]

Example 6 In the extraction experiment of Example 5, the pH was changed to deionized water.
The hydrochloric acid aqueous solution of No. 4 was poured into a column filled with fly ash, and the same experiment and analysis as in Example 5 were performed. Table 3 shows the results.
Shown in

Comparative Example 4 In the extraction experiment of Comparative Example 3, the pH was changed to deionized water.
The hydrochloric acid aqueous solution of No. 4 was poured into a column filled with fly ash, and the same experiment and analysis as in Example 5 were performed. Table 3 shows the results.
Shown in

[0031]

[Table 3]

Continued on the front page F term (reference) 3K061 AA24 AB01 AC01 BA01 BA08 3K065 AA24 AB01 AC01 BA01 BA07 BA08 CA04 4G066 AA20B BA26 CA31 CA33 CA46 DA02 DA07

Claims (5)

[Claims] 1. When incinerating dust in an incinerator, aluminum hydroxide and / or BET specific surface area is 30 m ² / g.
A dust incineration method comprising burning dust in the presence of the above transition alumina. 2. When incinerating dust in an incinerator, aluminum hydroxide and / or a BET specific surface area of 3 in the incinerator.
A dust incineration method, comprising adding 0 m ² / g or more of transition alumina to burn dust. 3. The incineration temperature of the dust (furnace atmosphere) is 500 to
The dust incineration method according to claim 1, wherein the temperature is 1100 ° C. 4. 4. The dust incineration method according to claim 1, wherein the aluminum hydroxide after incineration is transition alumina. 5. A transition aluminum hydroxide and / or a BET specific surface area is present in the incinerator is more than 30 m ² / g alumina, aluminum hydroxide and / or a BET specific surface area of the 30 m ² / g or more transition alumina The dust incineration method according to claim 1, wherein the method is a resin molded product kneaded in a resin.