JP3368530B2 - Dust incineration method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dust incineration method using an incinerator. Specifically, when abnormal heat generation in the incinerator is suppressed, toxic gas components such as dioxins generated during incineration are suppressed from being discharged from the incinerator, and when heavy metal ions are present in the combustion ash. Relates to a dust incineration method which has an effect of suppressing leakage of heavy metal ions due to rainwater and the like and which is excellent in environmental protection.

[0002]

2. Description of the Related Art In recent years, the amount of domestic dust and commercial dust has been increasing in Japan due to changes in lifestyle and improvement in income level. Furthermore, the types of dust have changed, and the current situation is that resin products are increasing dust due to an increase in petroleum-related products. Usually, these dusts are collected from various valuable components from the viewpoint of resource saving, resource recycling, and environmental protection, and then separated into noncombustible dusts and combustible dusts, and then subjected to landfill or incineration treatment.

[0003] By the way, the combustible dust that is usually discharged from ordinary households contains a large amount of combustible resin, and the following problems are currently occurring. That is, the thermoplastic resin that is the raw material of the dust bag has a large amount of heat generated during incineration and the temperature inside the incinerator rises abnormally, causing severe damage to the incinerator material, vinyl chloride, vinylidene chloride (wrap for food packaging). When burning chlorine-containing resins such as toxic dioxins may be released into the atmosphere, and when incineration residue ash is landfilled, heavy metal ions contained in the ash may cause rainwater, etc. at the landfill site. There is a possibility that it may dissolve in and leak.

In order to deal with such a problem, as for the temperature rise in the incinerator, a method of sprinkling water in the furnace to suppress the temperature rise in the furnace or a dust bag for collecting combustible dust is filled with calcium carbonate. A method is adopted in which the combustion heat of the resin is reduced by using the resin. On the other hand, the suppression of dioxin emission into the atmosphere is being studied from both directions of prevention of dioxin generation and adsorption recovery. As the former measures to prevent the generation, there are measures to suppress the generation of precursors of dioxin by completely burning the combusted material by operating the furnace in accordance with the guidelines for operating incinerators established by the Environment Agency and introducing a new type furnace. It is being advanced. Furthermore, as the latter adsorption recovery method, a method of introducing activated carbon or the like into the bag filter section of the dust collector is implemented. Further, as a measure for preventing leakage of harmful substances at the time of landfilling, there is adopted a method of insolubilizing contained harmful substances, solidifying them with cement or the like, and then disposing of them in landfill. However, these methods have to be individually dealt with according to their respective purposes such as protection of the refractory materials that make up the furnace, new installation / modification of equipment to prevent dioxin scattering, and measures to prevent leakage of heavy metal ions from incineration residual ash. First of all, enormous processing cost is required to carry out all the measures, and it was hoped that an inexpensive and effective method for multiple items would be developed.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to prevent harmful temperature rise of an incinerator during operation of the incinerator and suppress damage to the furnace material while scattering harmful exhaust gas such as dioxins into the atmosphere. The object of the present invention is to provide a dust incineration method that suppresses the above and is effective in preventing leakage of harmful substances contained in the incineration residual ash at the landfill.

In view of such circumstances, the inventors of the present invention have made earnest studies to achieve the above object, and as a result, at the time of dust combustion in an incinerator, it is extremely simple to make an aluminum compound coexist in dust as a combustion object. It was found that all the above objects could be satisfied by the method, and the present invention was completed.

[0007]

That is, according to the present invention, when incinerating dust in an incinerator, an amount of aluminum hydroxide and / or 0.001% by weight to 40% by weight with respect to the dust is used.
Another object of the present invention is to provide a dust incineration method characterized by burning dust in the presence of a transition alumina having a BET specific surface area of 30 m ² / g or more in an amount of 0.001 wt% to 30 wt%.

[0008]

The present invention will be described in more detail below. The greatest feature of the present invention is that when incinerating dust in an incinerator,
Aluminum hydroxide and / or BET specific surface area is 30m
^The purpose is to make the transition alumina present in an amount of ² / g or more. The aluminum hydroxide releases crystal water due to the combustion heat of dust incineration in the incinerator. Since the release of this crystal water is an endothermic reaction, the temperature inside the furnace is lowered. When aluminum hydroxide is fired at a specific temperature, crystal transition occurs and transitions to transition alumina (active alumina) having a large gas adsorption capacity and a high BET specific surface area having a high metal ion adsorption capacity. In the present invention, when incinerating dust in an incinerator, aluminum dust and / or transition alumina having a BET specific surface area of 30 m ² / g or more is present in the dust, and the incinerator is incinerated at a specific temperature to construct a furnace. Without damaging furnace construction materials such as refractories and joints, aluminum hydroxide added to dust at the time of incineration transfers to transition alumina with a high BET specific surface area, which adsorbs HCl and dioxins generated during incineration. In addition, when the residual ash is landfilled, heavy metal ions contained in the residual ash are adsorbed to have a leakage preventing effect, and when the transition alumina having a BET specific surface area of 30 m ² / g or more is present, the same HC is obtained.
The inventors 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 crystallization water such as gibbsite, bayerite, boehmite, and nordstrandite. However, among them, gibbsite is preferably used because it is easily produced at a low cost because it is produced in large quantities as a raw material for alumina and aluminum by the Bayer method. Further, sludge containing aluminum hydroxide used for wastewater treatment, aluminum hydroxide recovered from an alkaline solution used for aluminum surface treatment such as aluminum sash, and the like can also be used.

The method for allowing 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 adding dust and aluminum hydroxide to be incinerated in advance to the incinerator, a method of separately adding aluminum hydroxide to the incinerator while controlling the temperature in the incinerator separately from dust,
Resin molded product obtained by kneading aluminum hydroxide into resin [for example, shopping bags (shopping bags) in supermarkets,
Or, usually commercially available dust bags or combustible dust collection bags distributed by local governments, etc. However, these must be manufactured separately in advance. ], And burn with other dust.

The BET specific surface area used in the present invention is about 30 m.
The transition alumina of ² / g or more, preferably about 50 m ² / g or more, more preferably about 80 m ² / g or more may be any conventionally known one, and it is generally commercially available as activated alumina, and its crystalline form. Is represented by the general formula Al ₂ O ₃ which is 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 at the time of burning dust, the effect of suppressing exhaust gas, the effect of adsorption, and the effect of preventing elution of heavy metal ions are low. There is no limitation on the method of existing in these furnaces, for example, a method of mixing dust and transition alumina to be incinerated in advance and adding to the incinerator, transition alumina while controlling the temperature in the incinerator separately from dust. Is added directly into the furnace, a resin molded product made by kneading transition alumina into resin [for example, a shopping bag (shopping bag) in a supermarket, or a commercially available dust bag or a combustible dust collection distributed by a local government. Bags, etc. However, these must be manufactured separately in advance. ], And burn with other dust.

The amount of aluminum hydroxide with respect to dust is usually about 0.001% by weight to about 40% by weight, preferably about 0.01% by weight to about 30% by weight, and the BET specific surface area is 30.
The amount of transition alumina above m ² / g is usually about 0.001
% By weight to about 30% by weight, preferably about 0.01% by weight
It is about 20% by weight. When the amount of aluminum hydroxide and / or transition alumina having a BET specific surface area of 30 m ² / g or more at the time of incineration is less than the above range, the temperature suppressing effect,
When the adsorption effect of heavy metal ions is low, while the existing amount exceeds the above range, the combustion temperature reduction effect and the exhaust gas suppression effect due to chlorine gas, the adsorption effect, and the heavy metal ion adsorption effect are increased. Since the incineration residual ash increases, the upper limit is determined by the order of demand.

The type of incinerator used in the present invention is not particularly limited, but a stalker type incinerator, a fluidized bed type incinerator or a stalk type incinerator which is generally used in local governments or business establishments equipped with incinerators is used. It is applied to rotary kilns.

In the practice of the present invention, the incineration conditions are not unique depending on 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.
It is about 900 ° C. When the temperature in the incinerator is lower than 500 ° C., the burning rate in the furnace becomes slow, and it takes more time than normal operation to incinerate dust, which is not practical. Also about 1100 ℃
If the temperature exceeds the range, there is a risk of damaging the furnace, and the activity of the activated alumina that has undergone crystal transition from the added aluminum hydroxide is reduced. Crystal dislocation occurs in alumina and the specific surface area decreases. The incineration time is such that aluminum hydroxide after incineration usually has a crystalline form of χ-alumina, γ-alumina, θ-alumina, η-alumina, δ.
-BET with transition alumina such as alumina and κ-alumina
Specific surface area of about 30 m ² / g or more, preferably about 50 m ²
It suffices that the transition alumina has transferred to the transition alumina of not less than / g.

In the present invention, the aluminum hydroxide present in the incinerator undergoes a crystal transition from aluminum hydroxide to transition alumina due to the heat of incineration of dust, and exhibits gas absorption, adsorption and decomposition effects. Usually, in a commercial-based dust incinerator, even if it is continuously incinerated, or even intermittently used, since the incineration residual ash always remains in the furnace, there will be a transition alumina crystal transition from the above aluminum hydroxide, Exhibits the effect of removing harmful components in the generated exhaust gas, but when completely removing the incineration residual ash from the furnace, etc., add activated alumina to the furnace as necessary It can also be used as an effect-replacement material until the aluminum hydroxide to be converted into activated alumina. Of course, it is also possible to use a mixture of aluminum hydroxide and activated alumina.

Further, in the present invention, aluminum hydroxide is
0.0% in solid fuel produced by compression molding combustible dust
01% to 40% by weight, preferably 0.01% to
BET specific surface area of 30 m ² when contained 30% by weight
0.001% by weight or more for transition alumina of 1 g / g or more
It is also possible to exist in the incinerator and the combustion furnace in a state of containing 30% by weight, preferably 0.01% to 20% by weight. Solid fuel (RDF) produced by compression-molding dust and the like is also a method that has recently attracted attention as a measure for suppressing the amount of dioxins generated from small incinerators.

[0017]

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

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples below, 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 size 8 μm, manufactured by Sumitomo Chemical Co., Ltd.) and high-density polyethylene containing no aluminum hydroxide powder at all. Film 10
0 part by weight was burned and the amount of heat generated was measured using a bomb calorimeter. As a result, the heat of combustion of the high density polyethylene film containing aluminum hydroxide powder was 7791c.
al / g, and those not containing it were 11200 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 a polyethylene film, wood chips and cardboard, The incineration residual ash was obtained. The incineration residual ash is substantially activated alumina and has a BET specific surface area of 101
It was m ² / g. 1.5 mg of the incineration residual ash, 1.5 mg of aluminum hydroxide (C-31), and vinyl chloride powder 1
0 mg was put into a plastic combustion tester PCT (manufactured by Sugiyama Gen-Iriki) and burned under the conditions of a combustion temperature of 750 ° C., an air supply rate of 0.5 liter / minute, and a combustion time of 10 minutes. The generated HCl gas conforms to JIS-K7217 and is 20 mM.
After absorbing with sodium carbonate, it was quantified by the silver nitrate titration method. As a result, the detected amount of HCl was 4.3 mg, and it was 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 size is 3 μm.
A high-density polyethylene film containing 30% by weight of aluminum hydroxide powder of m (manufactured by Sumitomo Chemical Co., Ltd.) was burned in an electric furnace together with a piece of wood and cardboard to obtain incineration residual ash. This incineration residual ash was substantially activated alumina, and its BET specific surface area was 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 incineration residual ash. The glass column was set in a gas chromatograph, and a carrier gas (nitrogen) was flown while maintaining the temperature at 200 ° C., and 0.2 ml of a 4.8 μg / ml dioxin / n-hexane solution was injected with a 50 μl syringe in four times 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. Each of dibenzofuran and 1,3,4,7,8, -pentachlorodibenzofuran contained 1.2 μg / μl. 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 residual ash in the column was taken out, and the amount of dioxins contained in the incineration residual ash was analyzed.
The analysis used the method based on the “Manual for standard measurement and analysis of dioxins in waste treatment (February 1997)” created by the Environment Improvement Division, Water Environment Department, Living Health Bureau, Ministry of Health and Welfare. The results are shown in Table 1.

Example 4 The incineration residual 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. The results are shown in Table 1.

Comparative Example 1 A dioxin adsorption test was conducted in the same manner as in Example 5, except that the incineration residual ash prepared in the following procedure was used in place of the incineration residual ash used in Example 3. The results are shown in Table 1. (Preparation of incineration residual ash used in Comparative Example 1) A high-density polyethylene film containing 30% by weight of calcium carbonate was burned in an electric furnace together with wood chips and cardboard,
The incineration residual 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 conducted 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 in place of the incineration residual ash used in Example 3. The results are shown in Table 1.

[0025]

[Table 1]

Example 5 Mechanical batch furnace (model: Ebara B) with incineration capacity of 40 t / day
Type dust incinerator, manufactured by EBARA Infilco Co., Ltd.), gas cooling room, using an incinerator equipped with a multi-cyclone, 25 t of general household waste and 250 kg of aluminum hydroxide are put into the incinerator so that aluminum hydroxide is uniformly dispersed in the waste. It was charged and burned at about 7 hours. After the completion of combustion, 70 g of the fly ash collected was packed in a glass column having an inner diameter of 25 mmφ and a length of 600 mm with a shutoff valve at the bottom, and 200 ml of deionized water was poured from the top with the shutoff valve closed. 24
After standing for a period of time, the stop valve was opened and the extracted water was taken out from the bottom over 12 hours, and the concentration of heavy metal ions in the extracted solution was measured by an atomic absorption photometer. The heavy metal ion concentration in the test ash was calculated from the fluorescent X-ray analysis results. The extraction ratio of each heavy metal ion was calculated from the obtained heavy metal ion concentration in ash and the heavy metal ion concentration in the extract using the following formula. The results are shown in Table 2. Extraction rate (%) = [(amount of deionized water tested × content of heavy metal ions in extract) / (amount of ash tested × content of heavy metal ions in ash)] × 100

Comparative Example 3 A heavy metal ion extraction experiment was conducted in the same manner as in Example 5 except that the aluminum hydrate was not added in Example 5, and the fly ash recovered was used to burn the waste. It was
The results are shown in Table 2. When the alumina concentration in the same fly ash used in Example 5 and Comparative Example 3 was measured by a fluorescent X-ray measuring device, Example 5 showed an increase of 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 aqueous hydrochloric acid solution of No. 4 was poured into a column packed with fly ash, and the same experiment and analysis as in Example 5 were performed. The results are shown in Table 3.
Shown in.

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

[0031]

[Table 3]

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-60-64118 (JP, A) JP-A-9-173780 (JP, A) JP-A-9-75719 (JP, A) JP-A-9- 248423 (JP, A) JP-A-9-216984 (JP, A) JP-A-9-132682 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F23G 5/44 C08K 3 / 22 C08L 101/00 F23G 5/00 F23G 5/02 F23J 7/00

Claims (3)

(57) [Claims] 1. When incinerating dust in an incinerator, aluminum hydroxide in an amount of 0.001 wt% to 40 wt% and / or an amount of 0.001 wt% to 30 wt% with respect to the dust. The method for incineration of dust, comprising: burning dust in the presence of transition alumina having a BET specific surface area of 30 m ² / g or more. 2. When incinerating dust in an incinerator, aluminum hydroxide and / or 0.001 wt% in an amount of 0.001% by weight to 40% by weight based on the dust in the incinerator.
A dust incineration method comprising adding transition alumina having a BET specific surface area of 30 m ² / g or more in an amount of 30% by weight to burn dust. 3. The incineration temperature of dust (atmosphere in the furnace) is 500 to
It is 1100 degreeC, The incinerator method of Claim 1 or 2 characterized by the above-mentioned.