JP2000005720A - Waste treatment method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a waste disposal method capable of obtaining a sufficient effect of suppressing the release of chlorine compounds and reducing the treatment cost. SOLUTION: A concrete waste material and / or an ALC waste material are added to a waste material, and the waste material and the waste material are reduced to two.
Heat treatment at 50-350 ° C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating industrial waste and municipal waste.

[0002]

2. Description of the Related Art Conventionally, industrial waste including plastic waste, wood waste, paper waste, fiber waste, kitchen waste, metal waste, etc., and municipal waste are usually subjected to final treatment such as waste treatment after heat treatment. Has been provided. Generally, since the waste contains chlorine-containing substances, for example, chlorine-containing plastics such as polyvinyl chloride, when the waste is heated in a heating furnace, the released gas is highly reactive hydrogen chloride or the like. And the chlorine compound-containing gas may cause a decrease in durability of the heating furnace in some cases. In addition, the use of pyrolysis gas and pyrolysis oil obtained by pyrolysis of waste during heat treatment as fuel has been studied, but these often contain a large amount of chlorine compounds. Therefore, there is a problem that it is difficult to use as a fuel, and a great deal of cost is required for disposal. For this reason,
Prior to the heat treatment of the waste, an additive such as an alkali agent is added to the waste. This is because by the addition of the additive, the chlorine compound generated during the heat treatment is absorbed by the additive, and the release of the chlorine compound is suppressed. In addition, in order to increase the contact efficiency between the above additive and the chlorine compound and promote absorption of the chlorine compound into the additive, water is added to the additive in advance as a pretreatment, and these are made into a slurry or a pellet and then discarded. It is also added to products.

[0003]

However, in the above-mentioned prior art, a large amount of additives is required in order to sufficiently suppress the release of chlorine compounds, so that the raw material cost of the additives increases and the processing cost increases. There was a problem to do. In particular,
When the additive is made into a slurry or a pellet in advance,
There is a problem that a large cost is required for this pre-processing. In addition, since the pyrolysis oil obtained during the heat treatment is usually highly viscous and easily adheres to the inner wall of the heating furnace, the exhaust gas pipe, and the like, a large cost is required for maintenance such as cleaning of the inside of the heating furnace. There was a problem of soaring. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a waste disposal method capable of obtaining a sufficient effect of suppressing the release of chlorine compounds during heat treatment and capable of reducing treatment costs. .

[0004]

SUMMARY OF THE INVENTION The above-mentioned object is to reduce waste,
Add concrete waste and / or ALC waste,
The problem can be solved by a waste treatment method in which these wastes and waste materials are heat-treated under a temperature condition of 250 to 350 ° C. Further, the waste treatment method of the present invention comprises adding concrete waste material and / or ALC waste material to waste, and using one or more kinds selected from slaked lime, quick lime, calcium carbonate, iron oxide, and blast furnace slag. Add some additives, and add these wastes, waste materials and additives to 250
The heat treatment may be performed under a temperature condition of up to 350 ° C. Further, in the waste treatment method of the present invention, it is also possible to collect the solid residue obtained during the heat treatment after the solid residue is washed with washing water. It is preferable that the amount of the waste material added is set such that the number of moles of calcium contained in the waste material is 0.5 to 10 times the number of moles of chlorine contained in the waste material. The amount of the additive is
The number of moles of calcium contained in the waste material and the additive, or the total number of moles of calcium and iron is set to be 0.5 to 10 times the number of moles of chlorine contained in the waste. preferable. Further, it is preferable to use a waste material having an average particle diameter of 30 mm or less.
It is preferable to use a waste material having a specific surface area of 20 m ² / g or more. The heat treatment can be performed using a fluidized bed furnace, a fixed bed furnace, a moving bed furnace, or a rotary kiln.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The waste disposal method of the present invention will be described below in detail. The waste to be treated by the waste treatment method of the present invention includes polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyurethane, A
In addition to plastic waste such as BS resin, industrial waste including wood waste, paper waste, fiber waste, kitchen waste, metal waste and the like, and waste such as municipal waste can be mentioned. Specific examples of this waste include shredder dust, which is a crushed material such as interior parts such as waste automobiles and waste home appliances.

In the waste disposal method according to the present invention, concrete waste and / or ALC (lightweight cellular concrete) waste is first added to the above waste. As the concrete waste material, a general-purpose concrete material used as a building material or the like, for example, a concrete material obtained by appropriately mixing lime, silica sand, aggregate, filler, etc. with a hydraulic cement material such as Portland cement, etc. Waste materials that have been cured by adding water can be used. Concrete waste material usually has a porous structure on its surface and inside and has high surface adsorption.

[0007] ALC waste materials include general-purpose ALC materials used for building materials and the like, for example, a cement slurry obtained by adding water to the above-mentioned concrete raw material and using a foaming agent such as a surfactant to form a large amount of foam. , And a waste material obtained by a method of curing the same can be used. The ALC waste material usually has a porous structure on its surface and inside and has high surface adsorption.

[0008] Concrete waste and ALC waste are usually
3CaO.SiO ₂ , 2CaO.
Calcium silicate hydrate calcium silicate compounds such as SiO ₂ is hydrated _{(Ca 5 (Si 6 O 18} H 2) · 4H 2 O, 2
CaO · SiO ₂ · 1.17H ₂ O)
Contains 25% by weight.

The above concrete waste and ALC waste are preferably used after being granulated by a conventionally known pulverizing method or the like. The average particle size of the granular waste material is preferably 30 mm or less, for example, 1 to 30 mm. This average particle size is 30
If it exceeds mm, the effect of suppressing the release of chlorine compounds per weight of waste material is undesirably reduced. In this specification, the average particle size refers to a 50% particle size on a weight basis.

The concrete waste material and ALC waste material have a specific surface area of 20 m ² / g or more, for example, 20 to 30 m ² / g.
It is preferable to use those having m ² / g. If the specific surface area is less than 20 m ² / g, the effect of suppressing the release of chlorine compounds per weight of waste material is undesirably reduced. Further, it is preferable that the concrete waste material and the ALC waste material have a content of calcium silicate hydrate increased by previously removing reinforcing bars, aggregates and the like by a conventionally known mechanical sorting method or the like.

The amount of concrete waste material and ALC waste material added to the waste is such that the mole number of calcium contained in the waste material is 0.5 to 1 with respect to the mole number of chlorine contained in the waste material.
It is preferable to set so as to be 0 times. If the amount of addition is less than the lower limit of the above range, the effect of suppressing chlorine compound release is reduced. On the other hand, if the addition amount exceeds the upper limit of the above range, the raw material cost increases and the processing cost increases, which is not preferable.

Next, the waste and the waste material are heat-treated in an oxygen-free atmosphere or a gas atmosphere containing oxygen at a rate of 5 vol% or less. Although there is no particular limitation on the heating furnace used for the heat treatment, it is preferable to use a fluidized bed furnace, a fixed bed furnace, a moving bed furnace, or a rotary kiln from the viewpoint of heating efficiency and the like.

The temperature conditions for the heat treatment are from 250 to 35
0 ° C., preferably 300 to 350 ° C. If the heating temperature is lower than 250 ° C., the effect of suppressing the release of chlorine compounds decreases. If the heating temperature exceeds 350 ° C., a large amount of highly viscous oily substance is generated, and the cost required for maintenance such as heating furnace cleaning is undesirably increased. In addition, the heating cost is undesirably increased due to an increase in processing cost.

In the heat treatment under the above temperature conditions, a part of waste such as plastic waste such as polyvinyl chloride is thermally decomposed to generate chlorine compounds such as hydrogen chloride.
A solid residue containing a high calorific value combustible substance derived from plastic waste (hereinafter referred to as pyrolysis residue) can be obtained, but a gas containing a combustible substance (pyrolysis gas), an oily substance (pyrolysis oil), etc. Generates very little. The recovery amount of the above pyrolysis residues (excluding concrete waste material and ALC waste material)
Usually, it is 850 to 950 kg per ton of waste.

In this heat treatment, even if the waste contains a large amount of chlorine-containing substances such as polyvinyl chloride, it is difficult to release generated chlorine compounds such as hydrogen chloride. The reason why the chlorine compound is hardly released during the heat treatment can be considered to be due to the following mechanism. When the waste and the waste material are heat-treated under the above temperature conditions, desorption of bound water from calcium silicate hydrate contained in the waste material occurs. For example, calcium silicate hydrate Ca ₅ (Si ₆ O ₁₈ H ₂ ) · 4H ₂ O
In the above, the bound water between the crystals is eliminated to form Ca ₅ (Si ₆ O ₁₈ H ₂ ). A calcium compound obtained by desorbing bound water from calcium silicate hydrate has an unstable structure and high reactivity, and chemically reacts with a chlorine compound such as hydrogen chloride to easily absorb it. Therefore, the chlorine compound generated by the thermal decomposition of the waste is absorbed by the calcium compound and remains in the thermal decomposition residue. Further, since the concrete waste material and the ALC waste material have a porous structure on the surface and are highly adsorptive, a part of the chlorine compound is adsorbed by the waste material and hardly released. It is considered that the chlorine compound is hardly released by the above mechanism.

Further, during the above heat treatment, an aromatic organic chlorine compound such as a dioxin compound is hardly generated. It can be considered that the reason why the generation of the aromatic organic chlorine compound becomes less likely due to the heat treatment is due to the following mechanism. In general, it is known that when heat treatment is performed on waste containing an aromatic hydrocarbon and a chlorine compound, these may react with each other to form an aromatic organic chlorine compound such as a dioxin compound. According to the above heat treatment, the bound water desorbed from the calcium silicate hydrate is converted into a benzene ring in the aromatic hydrocarbon contained in the waste under the above temperature conditions as shown in the following formula (1). Decompose. 4C ₆ H ₆ + 18H ₂ O → 9CO ₂ + 15CH ₄ (1)

Thus, it can be considered that the decomposition of the aromatic compound serving as the raw material of the aromatic organic chlorine compound makes it difficult to generate the organic chlorine compound. Further, in addition to this, the release of the chlorine compound, which is a raw material of the aromatic organic chlorine compound, is suppressed as described above, so that a higher aromatic organic chlorine compound generation suppressing effect can be obtained. In addition, the dioxin compound here means polychlorodibenzo-p-dioxin or polychlorodibenzofuran.

Further, the dehydration reaction from calcium silicate hydrate usually occurs under a high temperature condition of 200 to 550 ° C. Therefore, when performing the heat treatment under the above temperature condition, waste, especially plastics The water can be supplied to the waste after the temperature of the debris or the like reaches a temperature at which thermal decomposition easily occurs, for example, 250 ° C. or more. For this reason, a sufficient amount of water is supplied during the heat treatment to increase the rate of the reaction represented by the formula (1), and a high effect of suppressing generation of an aromatic organic chlorine compound can be obtained.

On the other hand, when the above heat treatment is performed by adding only water to the waste instead of the waste material, the added water is heated to a temperature at which thermal decomposition of the waste is likely to occur (for example, Before the temperature reaches 250 ° C. or higher, it becomes steam and moves to a free port (furnace space) in the heating furnace, so that it does not easily come into contact with waste. For this reason, the amount of water that can participate in the reaction represented by the above formula (1) is insufficient, and the speed of this reaction is reduced, and a sufficient effect of suppressing the formation of an organic chlorine compound cannot be obtained. In general, when calcium hydroxide is placed under heating conditions, a reaction occurs in which hydrogen and oxygen derived from two hydroxyl groups are eliminated as water as shown by the following formula: Ca (OH) ₂ → CaO + H ₂ O Therefore, it is conceivable to use this as a water supply source instead of the above waste material,
Since the hydroxyl groups are ion-bonded to calcium, the amount of energy required for the dehydration reaction of calcium hydroxide depends on the dehydration reaction of calcium silicate hydrate in the waste material, for example, Ca ₅ (Si ₆ O ₁₈ H ₂ ) greater than the amount of energy required for the elimination reaction of intercrystalline bound water from · 4H ₂ O. For this reason, the dehydration reaction of the calcium hydroxide is carried out under higher temperature conditions, that is, usually, at a temperature condition of 450 ° C. or higher, and the temperature conditions at the time of the heat treatment,
That is, the rate of the dehydration reaction at 250 to 350 ° C. is relatively low. Therefore, when calcium hydroxide is used in place of the waste material, the amount of water supplied under the heat treatment conditions tends to be insufficient, and a sufficient effect of suppressing the production of organic chlorine compounds cannot be obtained.

Further, the chlorine content of the pyrolysis residue obtained by the above heat treatment can be reduced by a simple treatment such as washing away the chlorine compound remaining in the pyrolysis residue using washing water. . This is considered to be because, as described above, chlorine absorbed by the calcium compound in the waste material obtained by the dehydration reaction during the heat treatment is present in the pyrolysis residue in a water-soluble compound state. . For this reason, by the above-mentioned washing treatment, this pyrolysis residue becomes a substance containing a large amount of combustible substances having a high calorific value derived from plastic waste and containing almost no chlorine compounds and aromatic organic chlorine compounds. It is a calorific value, high in safety, and does not cause a decrease in durability of the combustion furnace during combustion, and has excellent characteristics as a fuel.

The thermal decomposition residue after the above-mentioned washing treatment can be suitably used as a fuel used in, for example, smelting and cement production processes. Prior to use as a fuel, it is preferable to remove metals, inorganic substances such as calcium silicate, and the like, and increase the content of combustible substances such as carbides before use as a fuel.

In the above waste disposal method, the release of chlorine compounds can be suppressed, and the generation of aromatic organic chlorine compounds such as dioxin compounds can be prevented. Therefore, it is possible to prevent a decrease in the durability of the heating furnace, and to enhance the work safety and environmental preservation.
Further, since inexpensive concrete waste material and / or ALC waste material is used without performing high-cost pretreatment, the treatment cost can be reduced. Further, no thermal decomposition oil is generated during the heat treatment, so that maintenance such as cleaning of the heating furnace can be facilitated, and the processing cost can be reduced. Further, a pyrolysis residue excellent in characteristics as a fuel can be obtained.

Further, the present invention relates to a method for producing concrete with waste.
Add waste and / or ALC waste and heat treat them
Not only the method of processing, but also the waste
Slaked lime, quicklime, calcium carbonate, iron oxide, and blast furnace
One or more selected from slag as an additive
It is also possible to adopt a method of adding and heating. Blast furnace
Slag is slag obtained from the iron making process, etc.
CaO, SiO _Two, Al_TwoO_ThreeEtc. are included. This
These additives are, for example, granulated so as to have an average particle size of 5 mm or less.
It is preferable to use it after shaping. Of this additive to waste
The addition may be performed before or after the addition of the waste material.
You may. In addition to the addition of waste materials,
Is also good.

The amount of the additive is such that the number of moles of calcium contained in the waste material and the additive or the total number of moles of calcium and iron is 0.1 to the number of moles of chlorine contained in the waste. It is preferable to set so as to be 5 to 10 times. If the amount of addition is less than the lower limit of the above range, the effect of suppressing chlorine compound release is reduced. On the other hand, if the amount of addition exceeds the upper limit of the above range, it is not preferable because the raw material cost increases and the processing cost rises.

[0025] By the addition of the above-mentioned additive, a part of the chlorine compound generated from the waste during the heat treatment chemically reacts with the additive and is absorbed therein. That is, when slaked lime, quicklime, calcium carbonate, or blast furnace slag is used as an additive, the chlorine compound reacts with the lime to generate calcium chloride. When iron oxide is used as an additive, the chlorine compound reacts with the chlorine compound to generate iron chloride. For this reason, the release of chlorine compounds such as hydrogen chloride and the generation of aromatic organic chlorine compounds from the waste during the heat treatment are more unlikely to occur.

[0026]

EXAMPLES The effects of the present invention will be clarified by showing specific examples. (Test Examples 1 to 4) As a waste, 50 g of polyvinyl chloride was used. The waste shown in Table 1 was added to the waste, mixed well, and then heat-treated in a nitrogen atmosphere. As the concrete waste material, a material having a calcium content of 11% by weight was used. This concrete waste material was made to have an average particle size of 0.1 mm by a pulverizing treatment. As the ALC waste material, a material having a calcium content of 20% by weight and an average particle size of 0.1 mm was used. Polyvinyl chloride used as waste has a chlorine content of 5%.
It was 6.6% by weight.

(Test Examples 5 to 14) Waste materials and additives shown in Table 1 were added to the same wastes as those used in the above test examples, mixed well, and then heat-treated in a nitrogen atmosphere.
Slaked lime, quicklime, calcium carbonate, and blast furnace slag used in these test examples had calcium contents of 54.1% by weight, 71.4% by weight, 40.0% by weight, and 30.0% by weight, respectively. Was used. The iron oxide used had an iron content of 69.9% by weight.

Test Examples 15 and 16 Wastes were heat-treated in the same manner as in Test Example 1 except that waste materials and additives were not added. The dioxin compounds in the gas discharged when the waste was heat-treated by the methods of the above test examples were measured. The measurement results are also shown in Table 1. In addition,
In Table 1, the Ca / Cl molar ratio indicates the ratio of the number of moles of calcium contained in the waste material or the additive added to the waste to the number of moles of chlorine contained in the waste. Also Fe / C
The 1 molar ratio indicates the ratio of the number of moles of iron contained in the additive added to the waste to the number of moles of chlorine contained in the waste.

(Test Examples 17 to 32) As waste, 50
Test Examples 1-1 except that g shredder dust was used.
Waste treatment was performed in the same manner as in No. 6. As the shredder dust, a shredder dust obtained by pulverizing interior parts of an end-of-life vehicle or the like and having a chlorine content of 3% by weight was used. The dioxin compound concentration in the gas discharged when the waste was heated by the method of each of the above test examples was measured.
Table 2 shows the measurement results. Dioxin compound concentration is
Indicated by toxicity equivalent.

[0030]

[Table 1]

[0031]

[Table 2]

From Tables 1 and 2, it can be seen that the content of dioxin compounds in the exhaust gas could be significantly reduced by adding waste materials and additives.

[0033]

As described above, in the waste treatment method of the present invention, it is possible to suppress the release of chlorine compounds and to prevent the generation of aromatic organic chlorine compounds such as dioxin compounds. it can. Therefore, it is possible to prevent a decrease in the durability of the heating furnace, and to enhance the work safety and environmental preservation. Further, since inexpensive concrete waste material and / or ALC waste material is used without performing high-cost pretreatment, the treatment cost can be reduced.

Claims (8)

[Claims] 1. A concrete waste material and / or an ALC waste material is added to a waste material, and the waste material and the waste material are added to the waste material in an amount of 250.
A waste treatment method, wherein a heat treatment is performed under a temperature condition of up to 350 ° C. 2. Addition of concrete waste material and / or ALC waste material to waste, slaked lime, quick lime,
One or more additives selected from calcium carbonate, iron oxide and blast furnace slag are added, and these wastes, waste materials and additives are heat-treated at a temperature of 250 to 350 ° C. Waste treatment method. 3. The waste treatment method according to claim 1, wherein a solid residue obtained during the heat treatment is recovered after being washed using washing water. 4. The waste treatment method according to claim 1, wherein the amount of the waste material added is determined by the number of moles of calcium contained in the waste material. A waste treatment method characterized in that the amount is set to be 0.5 to 10 times the number of moles of chlorine. 5. The waste treatment method according to claim 2, wherein the amount of the additive is adjusted by the number of moles of calcium contained in the waste material and the additive, or calcium and iron. Wherein the total number of moles is set to be 0.5 to 10 times the number of moles of chlorine contained in the waste. 6. The waste treatment method according to claim 1, wherein the waste material has an average particle size of 30 mm or less. 7. A waste treatment method according to claim 1, wherein the waste material has a specific surface area of 20 m ² / g or more. . 8. The waste treatment method according to claim 1, wherein the heat treatment is performed using a fluidized bed furnace, a fixed bed furnace, a moving bed furnace, or a rotary kiln. Waste disposal method.