JP2001115158A - Production method of granular soil using molten slag of refuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing regenerated granular soil from a molten slag of refuse occurring from an ash melting and solidifying facility. SOLUTION: Incineration ash of refuse is melted, then solidified, and granulated.; the resultant molten slag in an amount of about 20 wt.% is mixed under stirring with a water-containing soil occurring at construction sites or civil work sites to give a mixed soil which can be easily granulated; and the mixed soil is further mixed under stirring with a carboxyl-group-containing water-soluble polymer to be granulated and then is treated with a solidifying material such as lime.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the reuse of molten slag of refuse generated in large quantities when refuse incineration ash is melted in a melting furnace. More specifically, the present invention relates to a method of manufacturing granular soil using molten slag of garbage obtained by mixing molten slag of garbage with water-containing soil generated during construction and civil engineering and solidifying the mixture.

[0002]

2. Description of the Related Art Garbage generated in homes, shops, offices and the like is collected as general waste by a garbage truck and transported to a cleaning plant. The garbage collection plant separates and separates the collected garbage into general garbage and non-combustible bulky garbage, and then incinerates them at dedicated garbage incineration facilities. A large amount of incineration ash is generated from the incineration facility during the incineration treatment, and this incineration ash contains a large amount of harmful substances such as dioxins and highly toxic and hardly decomposable compounds.

In order to reduce these harmful substances from the incinerated ash and to reduce the absolute amount of the incinerated ash,
Melting of incinerated ash at an ultra-high temperature of about 1200 ° C. or more in an ash fusion solidification facility is being carried out at some of the cleaning plants.
The organic matter in the incineration ash is completely burned by this melting process,
In addition, since harmful substances are completely gasified and diffused, a dark black glassy solid containing harmful substances having a numerical value within an allowable range is generated. The “molten slag” of garbage is a general term for solidified particles obtained by finely crushing and solidifying the glassy solid.

[0004] Conventionally, attempts have been made to use molten slag of garbage as a recycled material as a substitute for materials such as concrete blocks for construction and natural aggregates. (1.88 mm), it cannot be compacted and is therefore not suitable for backfilling, etc., and is currently transported as general waste to final disposal sites for landfill disposal.

[0005]

By the way, harmful compounds such as dioxin in incineration ash generated from garbage incinerators have been widely recognized as highly carcinogenic environmental pollutants, and harmful substances in incineration ash have been recognized. As a result, urgent removal measures have been demanded, and in response to this, plans are underway to install smelting and solidification facilities at municipal waste management plants nationwide and to establish new facilities. For this reason, it is inevitable that a large amount of waste slag will be generated from waste management plants in each local government.However, in the Tokyo metropolitan area and other local governments, final disposal sites as landfill disposal Since there is a limit in securing the molten slag, it is expected to utilize the molten slag as a resource.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and as a result of intensive research on utilizing the physical properties of molten slag of garbage, the molten slag has been applied to hydrous soil generated from a construction site or the like. It has been found that when mixed, the fine particles of the molten slag combine with the particles of the hydrous soil to transform the highly viscous hydrous soil into finely granular hydrous soil. More specifically, the present invention melts hydrated soil and garbage incineration ash generated in construction work, civil engineering work, etc., solidifies this, and mixes in advance with molten slag obtained by granulation, and then forms a carboxyl group. The method is characterized by a method for producing granular soil using molten slag of refuse obtained by mixing with a group-containing water-soluble polymer and further treating with a solidifying material such as lime.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The molten slag of refuse used in the present invention can be obtained through the following processing steps. First, the incinerated ash generated from the refuse incineration facility is refined, and then heated and burned in an electric melting furnace of the ash melting and solidifying facility at an ultra-high temperature of about 1200 degrees or more. The molten material generated by this heating and combustion is cooled and solidified in a cooling treatment facility, and the generated dark black glassy solid is subjected to a magnetic separator to remove metal pieces.
It is crushed into particles by a crusher.

[0008] The molten slag of garbage thus obtained is
This is a water-repellent glassy solidified particle having a small particle size with a particle size in the range of 0.075 to 1.18 mm and an average particle size of about 0.68 mm. The molten slag is stirred and mixed with hydrous soil generated during construction work and the like. As the hydrous soil used in the present invention, use is made of a soft or highly sticky construction generated soil and construction residual soil which are generated with general civil engineering and construction work such as building construction work, residential land development work, underground pipe work, and the like. be able to.

In the present invention, molten slag is added to hydrous soil and mixed with a stirrer. When the molten slag is added to the hydrous soil and agitated and mixed, the finely solidified granules constituting the molten slag are combined with the soil particles of the crushed hydrous soil, so that the hydrous soil is easily mixed into granules containing the molten slag. Transforms to soil.

[0010] The rate of adding molten slag to hydrous soil is as follows:
About 20% by weight is preferred. Mixing ratio is 20% by weight
If it exceeds, the molten slag remains as a lump even after stirring and mixing, and the bonding property between the hydrated soil and the molten slag does not occur. For this reason, the molten slag remains in the hydrated soil in the form of fine solid granules having no hydration, and does not react with the molten slag even when mixed with the carboxyl-based water-soluble polymer described below. Cannot be generated.

The water-soluble polymer used in the present invention is 100
It is a polymer that usually dissolves 0.5 g or more in ml of water. The polymer has a carboxyl group as a hydrophilic group, and a monomer having a carboxyl group is usually 1 to 80 mol%, preferably 5 to 60 mol, of all monomer units constituting the polymer. %included. Also, the carboxyl group is
It may be present in either the free acid or salt form. Examples of the type of salt include salts of alkali metals such as sodium and potassium, salts of alkaline earth metals such as calcium and magnesium, ammonium salts, amine salts such as alkylamines having 1 to 18 carbon atoms, alkanolamines, and the like. There is a mixture of two or more, but preferably salts of alkali metals.

Examples of such a water-soluble polymer include a copolymer of (meth) acrylic acid or a salt thereof and (meth) acrylamide, a copolymer of maleic acid or a salt thereof and vinyl acetate, and a copolymer of itaconic acid or a salt thereof. Synthetic water-soluble polymers such as copolymers with (meth) acrylamide, natural water-soluble polymers such as arabic gum, karaya gum, tranto gum, alginic acid, and semi-synthetic water-soluble polymers such as carboxymethylcellulose, carboxyhydroethylcellulose, and modified guar gum Examples of the polymer are:

Among the above water-soluble polymers containing a carboxyl group, a copolymer of (meth) acrylic acid or a salt thereof and (meth) acrylamide is preferred. (Meta)
Examples of the (meth) acrylamide-based polymer containing acrylic acid or a salt thereof include those obtained by copolymerizing (meth) acrylic acid or a salt thereof and (meth) acrylamide,
(Meth) acrylamide homopolymer may be partially hydrolyzed.

Further, the above-mentioned carboxyl group-containing water-soluble polymer includes a monomer containing a sulfonic acid group as a hydrophilic group,
For example, copolymerization may be carried out including vinyl sulfonic acid, acrylic sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and salts thereof. Further, a hydrophobic monomer such as an olefin, an acrylate or a vinyl ester may be contained as long as it does not inhibit water solubility.

The amount of the water-soluble polymer containing a carboxyl group varies depending on the mixing ratio of the molten slag, the water content of the water-containing soil, and the like. Is 0.07 to 0.1% by weight based on the raw material to be treated. In addition, the stirring and mixing of the carboxyl group-containing water-soluble polymer and the raw material to be treated are preferably performed with gentle stirring using a stirrer, usually for about 0.8 to 2 minutes.

When the carboxyl group-containing water-soluble polymer is added to the raw material to be treated in the above ratio and gently stirred and mixed for about 50 seconds or more with a stirrer, the carboxyl group-containing water-soluble polymer makes the surface of the granular soil uniform. After coating, the free water between the soil particles inside the granular soil and the solid particles of the molten slag is sucked and dissolved. Therefore, the water inside the soil sucked by the carboxyl group-containing water-soluble polymer loses its properties as free water,
It is fixed on the surface of the granular soil as pseudo-fixed water (adsorbed water), and the granular soil does not adhere to each other, and is granulated into a sphere by stirring and mixing.

According to the present invention, a solidified material such as lime is uniformly adhered to the surface of the granular soil in order to stabilize the film fixed on the surface of the generated granular soil and maintain the coating in a granular form for a long period of time. The solid material used in the present invention is preferably one that easily adheres to the surface of the granular soil, and it is preferable to use lime powder having an average particle size of 0.5 mm or less. The lime as a solidifying material contains calcium oxide and calcium hydroxide. Specifically, slaked lime, quicklime, hydraulic cement, lime-based improving material, cement-based improving material, etc. can be applied, but dehydration and solidification Fast lime powder is preferred. The amount of solidified material
It is 0.2 to 20% by weight, preferably 0.5 to 20% by weight, based on the raw material to be treated.

When a solidified material such as quicklime adheres to the surface of the granular soil coated with a water-soluble polymer film containing a carboxyl group that has been sucked and dissolved, the water in the film reacts with the solid material to generate heat. Since the slaked lime is formed, the water develops in the film by evaporating the water and penetrating from the surface with a high lime distribution, and the pozzolanic reaction develops the strength. Curing can be performed to further develop the strength of the granular soil.
Curing is usually carried out by leaving at room temperature for 1 to 7 days, preferably about 3 to 6 days.

In the granular soil produced by the production method of the present invention, the solidified granular material of the molten slag of garbage having a short average particle size in the range of 0.075 to 1.18 mm constitutes the hydrous soil. The particle size of the generated granular soil is in the range of 0.425 to 9.50 mm to meet the requirement of 13.0 mm or less which is the standard of Tokyo, and the particle size is also Since the equilibrium is maintained widely, it is possible to obtain a granular soil having excellent ground permeability, strength characteristics, and granular soil characteristics equivalent to those of the conventional granular improved soil.

[0020]

EXAMPLES Hereinafter, some examples will be described as specific examples of the present invention, but the present invention is not limited to these examples. Example The incineration ash generated from a garbage incineration facility was heated and burned in an electric melting furnace of an ash fusion and solidification facility under an ultra-high temperature condition of about 1200 ° C. or more, and was cooled and solidified in a cooling treatment facility. The dark glassy solid was subjected to a magnetic separator to remove metal pieces, and then crushed by a crusher to prepare a molten slag of solid granulated garbage.

The prepared molten slag was put into 0.075 mm,
Examination of the granular soil with each of the 1.18 mm and 2.36 mm sieve testers shows that particles having a cumulative ratio of about 90% to 0.45 to 1.18 mm within the range of 0.075 to 1.18 mm. Accounted for more than%. The average particle size is 0.68 mm
Met. The results of the particle size distribution measurement test of the molten slag are shown in FIG. 1 as a grain distribution curve.

On the other hand, a water content of 98%
5 kg of hydrous soil mainly composed of Kanto loam and 1.0 kg of the above-mentioned molten slag were put into a mixer having a capacity of 20 liters and stirred and mixed for about 60 seconds to obtain a mixed soil which was easily granulated. Next, 6 g of a copolymer of acrylamide and sodium acrylate was added to the granular soil obtained in the above step (0.
1% by weight) and gently stirring and mixing for about 90 seconds, then adding 180 g of quicklime powder and stirring for 30 seconds with little external pressure to obtain granular soil coated with slaked lime. When this granular soil is subjected to a sieve tester of 0.075 mm, 1.18 mm, and 2.36 mm to measure the particle size and the like, the particle size is in the range of 0.425 to 9.50 mm,
The accumulation rate was small, medium, and large, and the particle size was widely balanced. The average particle size was 2.3 mm. The results of the particle size distribution measurement test of the obtained granular soil are shown in FIG. 2 as a granular soil distribution curve.

The particle size of the granular soil thus prepared conformed to the Tokyo Metropolitan Standard (particle size of 13.0 mm or less) as described above, and had the same particle size and particle size distribution as high quality sand. In addition, the ground support and shear strength characteristics were equivalent to those of the conventional granular improved soil. Furthermore, it did not become soft even by rainwater or the like, had good water permeability equivalent to river sand, did not show any turbidity in water after water permeation, and no separation of molten slag was recognized.

Comparative Example The molten slag of garbage obtained in the examples was used alone as a compacting material, but the average particle size was as fine as 0.68 mm, and the cumulative ratio was 0.45 to 01.180 mm. Since the particles up to 90% or more accounted for 90% of the particles, they could not be compacted. Further, upon immersion in water, black turbid water in which the molten slag was dissolved came out.

[0025]

According to the present invention, since the hydrated soil and the molten slag of the garbage are mixed in advance, the hydrated soil becomes a fine granular hydrated soil containing the particles of the added molten slag. The penetration of the carboxyl group-containing water-soluble polymer is improved, and the resulting granular soil becomes closer to river sand. In addition, it was difficult to stir a highly viscous hydrous soil, but by adding molten slag, the molten slag plays a role as a stirring aid, so the load on the stirrer can be reduced and the durability can be reduced. Can be improved.

Further, since the molten slag of garbage, which has been mostly landfilled as landfill waste, can now be used as a recycled resource for reclaimed granular soil, the utilization of the molten slag is enhanced, contributing to environmental problems. large. Further, when recycling the molten slag, it is not necessary to intervene a special processing step in the molten slag itself, and the molten slag generated in the ash fusion solidification facility can be used as it is, so that the cost required for the recycling processing can be reduced.

Further, the granular soil does not become dark black of the molten slag and has almost the same color as ordinary soil. Therefore, even if it is not subjected to coloring treatment, it can be used as grass soil, groundwork, or sand of bunker. Can be used.

[Brief description of the drawings]

FIG. 1 shows a grain distribution curve of molten slag.

FIG. 2 shows a granular soil distribution curve of the granular soil obtained in Example 1.

Claims (2)

[Claims] After melting the incinerated ash of garbage, solidifying it and mixing the molten slag formed into particles with water-containing soil, mixing the carboxyl group-containing water-soluble polymer, and further solidifying lime etc. A method for producing granular soil using molten slag of garbage treated with wood. 2. The method according to claim 1, wherein the molten slag is mixed with the hydrated soil in an amount of 20% by weight.