JP2001292634A - Method for producing improved soil by using liquid slag of waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing improved soil obtained by improving water-containing soil formed in the sites of civil engineering and construction by using a molten slag of a waste formed in ash-melting and solidifying facilities and direct melting facilities. SOLUTION: The molten slag obtained by melting the burned ash of the waste, solidifying the melted ash, and granulating the solidified ash, in an amount of about 20 wt.% is mixed and stirred with the water-containing soil formed in the construction site and the civil engineering site to provide a mixed soil which can be easily granulated, and the resultant mixed soil is treated with a solidification 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 an improvement in which water-containing soil generated at a civil engineering construction site is improved by using molten slag generated in a large amount when refuse or incinerated ash of refuse is melted in a melting furnace. It relates to a method for producing soil.

[0002]

2. Description of the Related Art Conventionally, most of the residual soil generated from civil engineering construction sites is hydrous soil, so it cannot be reused and is landfilled or transported to other places for disposal. Is becoming a problem. For this reason, as a method for reusing the remaining soil generated from a civil engineering construction site, a method for treating the remaining soil using quicklime for a water-bearing soil in which the clay having a relatively low water content is not so high is disclosed in JP-A-54-121086.
JP-A-4-345885, JP-A-8-73852,
It has been developed as JP-A-8-41460 and JP-A-8-48975.

On the other hand, garbage generated in homes, shops, offices, and the like is incinerated in a garbage incineration facility of a waste cleaning plant, and a large amount of incineration ash is generated from the incineration facility along with the incineration processing. This incinerated ash contains a large amount of harmful substances such as dioxins and compounds that are highly toxic and hardly decomposed. Therefore, in order to reduce these harmful substances from the incinerated ash and to reduce the absolute amount of the incinerated ash, the garbage and incinerated ash should be further melted in an ash melting and solidification facility under ultra-high temperature conditions of about 1200 degrees or more. Has been implemented in some waste treatment plants.

[0004] By this melting treatment, organic substances in the incineration ash are completely burned, and harmful substances are completely gasified and dissipated, thereby generating molten inorganic substances containing harmful substances having a numerical value within an allowable range. The `` molten slag of garbage '' of the present invention refers to an inorganic substance obtained by directly melting general waste and industrial waste and an inorganic substance obtained by melting incinerated ash of general waste and industrial waste in a cooling treatment facility. Refers to a particulate solidified product obtained by finely crushing a dark black glassy solidified product obtained by cooling and solidifying in step.

In recent years, harmful compounds such as dioxins in incineration ash generated from refuse incinerators have been widely recognized as highly carcinogenic environmental pollutants. Plans are underway to add and install facilities, and it is inevitable that a large amount of garbage-melting slag will be generated from waste management plants in each local government. For this reason, attempts have been made to use recycled materials from molten slag of garbage as substitutes for materials such as concrete blocks for construction and natural aggregates.

[0006]

However, since the particle size of the molten slag of the refuse is a single particle size (0.0075 to 1.18 mm), it cannot be compacted and is not suitable for backfilling materials. At present, most of them are transported to final disposal sites as general waste and landfilled. However, in each local government, including the Tokyo metropolitan area, there is a limit in securing a final disposal site for landfill disposal, and thus there is an expectation for measures to utilize the molten slag as a resource.

[0007] In addition, in the conventional method for treating residual soil obtained by adding and mixing quicklime to residual soil generated during civil engineering and construction work,
There is a problem that the soil mass easily adheres to the mixing machine or the like and the treatment is difficult, and even if the treatment is forcibly performed, the strength cannot be expected to be improved, and the yield as the reclaimed soil is poor. For this reason, there has been a demand for an improvement measure that can utilize the water-containing residual soil generated from a civil engineering construction site as a resource.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned situation, and as a result of intensive studies to utilize the physical properties of molten slag of garbage, the molten slag has been applied to hydrous soil generated from construction sites and the like. It has been found that upon mixing, the fine particles of the molten slag combine with the particles of the hydrous soil to transform the highly viscous hydrous soil into fine-grained hydrous soil. More specifically, the present invention is characterized in that a solidifying material such as lime is added to a mixture of water-containing soil and molten slag of solidified / particulated garbage and stirred.

[0009]

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, after the incinerated ash generated from the refuse incineration facility is refined, it is 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.

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. This molten slag is stirred and mixed with hydrous soil generated during construction work or 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 generated with general civil engineering and building 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 of garbage is added to hydrous soil and mixed with a stirrer. When the molten slag of garbage is added to the hydrous soil and agitated and mixed, the finely solidified granules constituting the molten slag of garbage combine with the ground particles of the crushed hydrous soil, so that the hydrous soil contains the molten slag. It transforms into granular soil that is easily granulated.

[0012] The ratio of adding molten slag to hydrous soil is as follows:
About 10 to 30% by weight is preferable. 30% mixing ratio
If the weight is exceeded, the molten slag remains as a lump even after stirring and mixing, so that the binding between the hydrous soil and the molten slag does not occur, and the molten slag is in the form of fine solid granules that do not have hydrous properties. Remains inside. For this reason, even if a solidifying material such as quick lime described later is added and stirred, it does not react with the molten slag, so that granular soil cannot be generated.

The solidified 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. 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, and the like can be applied, but quicklime powder having a high dehydration and solidification rate is preferable. The addition amount of the solidifying material is 0.2 to 20% by weight, preferably 0.5 to 20% by weight, based on the raw material to be treated.

When the solidified material, for example, quicklime, is added to the mixture obtained by adding the molten slag to the water-containing soil and stirring and mixing, and then stirring and mixing, the quicklime uniformly covers the surface of the granular soil, It reacts with the free water between the soil particles in the soil and solid particles of the molten slag to generate heat and becomes slaked lime, and the free water evaporates and is fixed to the surface of the granular soil by the pozzolanic reaction while penetrating from the surface with high lime distribution. As a result, a granular soil having excellent strength that does not adhere to each other is generated. In addition,
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.

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 incinerated 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 then cooled and solidified in a cooling treatment facility. The dark black 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 used for 0.1 g.
Examination of the granular soil with a sieve tester of 075 mm, 1.18 mm and 2.36 mm revealed a grain size of 0.075 to 1.1.
Within the range of 8 mm, particles with a cumulative rate of 0.45 to 1.18 mm accounted for about 90% or more.

On the other hand, a water content of 98% collected from a building site
5 kg of hydrous soil mainly composed of Kanto loam and 0.5 to 1.5 kg of the above-mentioned molten slag were put into a 20-liter mixer and stirred and mixed for about 60 seconds to obtain a mixed soil which was easily granulated. Next, quick lime powder 180 was added to the mixture obtained in the above step.
g was further added and the mixture was stirred for 30 seconds with little external pressure, to obtain granular soil coated with slaked lime. The granular soil was measured using a sieve tester of 0.075 mm, 1.18 mm, and 2.36 mm to measure the particle size and the like.
5 to 9.50 mm, the accumulation rate is small, medium, and large, and the particle size is widely balanced. The average particle size is 2.3 mm.
Met.

The particle size of the granular soil thus prepared had a particle size and a particle size distribution equivalent to those of good-quality sand. In addition, the ground support and shear strength characteristics were equivalent to those of the conventional granular improved soil. Further, 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 the water after water permeation, and no separation of the molten slag was observed.

[0018]

According to the present invention, since the hydrated soil and the molten slag of garbage are mixed in advance, the hydrated soil becomes fine granular soil containing the particles of the added molten slag, and the surface thereof is formed. Since it is covered with the solidified material, the generated granular soil can be obtained with excellent strength and closer to river sand. In addition, it was difficult to stir the highly viscous hydrous soil, but by adding the 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.

In addition, since the molten slag of garbage and the remaining soil of civil engineering construction sites, most of which have been conventionally landfilled as landfill waste, can be used as recycled resources for improved soil, the availability of molten slag and hydrous soil can be improved. And contribute to environmental issues. Further, when recycling the molten slag and the water-containing soil at the construction site, there is no need to intervene a special processing step, and the recycled slag can be used as it is, so that the cost required for the recycling processing can be reduced.

Since the granular soil does not become dark black and has almost the same color as ordinary soil, it can be used as grass soil, groundwork, or sand of a bunker without coloring treatment. Can be.

Claims (2)

[Claims] 1. A method for producing an improved soil using a molten slag of garbage, wherein a solidifying material such as lime is added to a mixture of a hydrous soil and a molten slag of garbage solidified and granulated, and the mixture is stirred. . 2. The molten slag is added to the water-containing soil in an amount of 10 to 10.
2. The mixture according to claim 1, wherein the mixture is 30% by weight.
A method for producing improved soil using a molten slag of garbage as described in 1 above.