JP4018249B2 - Method for manufacturing vegetation base material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a vegetation base material, and more particularly to a method for effectively using construction sludge discharged at a construction site or civil engineering work.
[0002]
[Prior art]
Various types of sludge are generated at relatively large construction sites, and this treatment is a problem. Specific sources of construction sludge are surplus muddy water in the muddy water shield, surplus muddy water in the underground continuous wall, and surplus muddy water in the field.
[0003]
Since these sludges are generated in large quantities, the volume has to be reduced in the form of a dehydrated cake, and, in some cases, must be discarded after cement solidification or the like, which requires a large disposal cost. Since such a sludge cake itself is composed of fine particles, it is treated as “sludge” of industrial waste.
[0004]
[Problems to be solved by the invention]
However, the generation of expenses necessary for disposal of construction sludge not only leads to an increase in construction costs, but the situation is that the disposal site is tightly secured. Therefore, its effective use is strongly desired.
[0005]
Therefore, in some cases, attempts have been made to use red jade soil that has been aggregated by firing as a soil improvement material. However, since it is an inorganic material, it has been insufficient from the viewpoint of improving the environment.
[0006]
On the other hand, in order to use sludge cake as a vegetation soil having a relatively high versatility, the sludge cake is not aggregated and cannot be used as a green soil for a “vegetation base material” as it is.
[0007]
In the construction of lightweight aggregates for construction by firing, the purpose is to produce these lightweight and porous granular aggregates by firing these sludges at a high temperature of 1000 ° C or higher. It cannot be. Moreover, in the baking at a high temperature of 1000 ° C. or higher, the lime content in the material changes from calcium carbonate (CaCO ₃ ) to quick lime (CaO), and therefore becomes alkaline and unsuitable for vegetation. Moreover, the increase in cost and energy consumption due to high-temperature firing is a problem.
[0008]
Furthermore, in the conventional granulation / firing method, the particle diameter is 5 mm to 20 mm, and these are handled as gravel materials, and do not satisfy the standard as a guest soil material that “the gravel content is 50% or less”.
[0009]
Thus, conventionally, there is hardly any modification technology for making construction sludge cake a property that does not belong to the category of industrial sludge and using it as a base material for vegetation.
[0010]
The present invention has been made to solve such a conventional problem, and it is an object of the present invention to provide a method for producing a vegetation base material that effectively uses discarded construction sludge.
[0011]
[Means for Solving the Problems]
The present invention is configured as follows in order to solve the technical problems described above. In other words, after baking dehydrated sludge cake generated in construction work at 1000 ° C or less, the particle size is adjusted so that the weight ratio of gravel is 50% or less, and organic compost and chemical fertilizer are added to this. To do.
(Dehydrated sludge cake)
Examples include dewatering cakes for dam aggregate plants, dewatering cakes for shield construction mud, and dewatering cakes for BW pile construction.
(Baking)
The dehydrated cake is baked at a low temperature of 1000 ° C. or lower, preferably 600 to 800 ° C., and is treated so as to obtain prevention of pH value and adhesion between particles (aggregation) to obtain the necessary minimum strength. Is done. The dehydrated cake has a low strength by low-temperature baking, and the particle size can be easily adjusted by a crusher described below. As the baking machine, a direct hot air rotating type (rotor type) drying machine, a rotary kiln type baking machine, or the like can be used.
(PH stabilizer)
In order to prevent an increase in pH value due to decarboxylation of Ca during firing, it is appropriate to add a pH stabilizer such as gypsum to the sludge dehydrated cake before firing as necessary. Depending on the type of sludge, the pH value may increase at 600 to 800 ° C., so that the calcined material can be kept neutral by adding gypsum or the like regardless of the calcining temperature. As other pH stabilizers, calcium chloride, calcium nitrate and the like can be used.
(Fracture by crusher)
In order to satisfy the standard of particle size (gravel content of 50% or less) as vegetation soil, it is preferable to undergo a crushing process with a crusher after firing, if necessary. Here, the gravel usually refers to those having a particle size of 2 mm or more.
(Addition of organic compost and chemical fertilizer)
It is preferable to add organic compost or chemical fertilizer to secure compost and fertilizer as vegetation soil. Examples of organic compost in this case include materials selected from bark compost, chicken manure, rice straw, rice husk, and weeding. Organic compost can be added, for example, in a volume ratio of 10 to 30% with respect to the apparent volume.
[0012]
In this way, both physical properties and physicochemical properties are secured as vegetation soil using sludge as a material.
[0013]
As described above, the top soil (vegetation base material) that has been lacking in recent years can be replaced with the vegetation base material of the present invention, and construction sludge is made from the soil that originally formed the ground. The purpose of recycling is also in line with the goal of recycling.
[0014]
In general, construction sludge does not contain heavy metals, so environmental problems due to soil contamination do not occur.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in more detail with reference to FIG.
[0016]
FIG. 1 is a diagram showing a process for producing a vegetation base material of the present invention.
[0017]
First, the sludge generated in the muddy water treatment process of the dam aggregate plant is dehydrated by a dehydrator to obtain a dehydrated cake.
[0018]
Secondly, gypsum was added to the dehydrated cake to adjust the pH value not to increase during firing. As shown in FIG. 3, cakes A, B, and C were prepared and their baked products were examined. When the temperature of the baked products was 600 ° C. or lower, the pH value was near neutral, but increased at 800 ° C. or higher. There was a trend. In FIG. 3, the pH value of cake B was constant regardless of the temperature, but it was estimated that this was due to the fact that cake B had a large amount of calcium sulfate (gypsum) component. From this, it is considered that the addition of gypsum contributes to the stabilization of the pH value of the fired product.
[0019]
Further, when firing at a temperature of 600 ° C. or higher, the ratio of particles having a particle size exceeding 425 μm rapidly increases and agglomeration proceeds. In order to confirm this, three types of cakes A, B, and C were formed, and the relationship between the baking temperature and the aggregate property was determined by a test. This test was performed by a method of sieving the fired product while shaking in water. The results are shown in FIG. It can be seen that agglomeration proceeds in all cakes.
Thirdly, the dehydrated cake was baked with a rotary kiln type baking machine to obtain a baked product having a particle size of about 5 to 10 mm.
[0020]
When this was crushed with a jaw crusher having an opening of about 5 ± 3 mm, an aggregate having a particle size of 2 mm or more and a weight ratio of 50% or less was obtained.
[0021]
This aggregate was put into a mixing tank, and composts (bark compost, chicken manure, rice straw) were added at a volume ratio of about 20% with respect to the apparent volume. Further, 4 kg / m ³ of slow-acting fertilizer (High Control (trade name) manufactured by Asahi Kasei Corporation) was added as a chemical fertilizer.
[0022]
The vegetation base material obtained in this way was vegetated on enoki, konara, salamander, radish, yamahagi, creeping red fex, white clover, and various wildflowers. As a result, it was revealed that the germination and the breeding ability were remarkably good.
[0023]
【The invention's effect】
According to the present invention, a vegetation base material having good air permeability and water retention was obtained by agglomerating sludge generated in construction work or sludge dewatered cake. According to this vegetation base material, soil formation by microorganisms is promoted and recycling to the environment becomes possible.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a method for producing a vegetation base material of the present invention.
FIG. 2 is a graph showing the relationship between the baking temperature of sludge cake and pH.
FIG. 3 is a diagram showing the relationship between the baking temperature of the sludge cake and the aggregate property.

Claims (2)

The dehydrated cake of sludge produced in construction work, in order to prevent the p H value increases by decarboxylation of calcium during the firing, calcium chloride as a p H stabilizer, calcium nitrate, one or more of the plaster was added, after calcination at 1000 ° C. or less, vegetation base weight ratio of gravel content and the particle size adjusted to be 50% or less, and wherein this adding organic compost, and fertilizers A method of manufacturing the material. The method for producing a vegetation base material according to claim 1 , wherein the organic compost is a material selected from bark compost, chicken manure, rice straw, rice husk, and weeding.

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