JPH1029848A - Treatment of fly ash, and artificial soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reuse fly ash discharged from a coal-fired power plant, or the like. SOLUTION: In this treatment, fly ash A discharged from coal-fired power generation facilities is mixed with solid clay E obtained by treating discharged sludge/(surplus soil) B from a construction site, or the like, to obtain a mixture and then, a cement based solidifying agent H, quick lime I and a pH adjuster J are added to this mixture and they are agitated and mixed together with an agitation mixer 8 to form artificial soil M. At this time, an exhaust gas L exhausted from an engine is introduced into the agitation mixer 8 to effectively reduce pH of the artificial soil M. Thus, the objective artificial soil M which can be used in a wide variety of application fields, is produced. Also, according to use of the artificial soil M, the discharged sludge/soil B or good quality soil-and-sand F may further be mixed to the artificial soil M and further, an organic fertilizer G contg. microorganisms appropriate for plant growth may be added to the artificial soil M.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fly ash processing method and an artificial soil which enable effective use of fly ash (coal ash) discharged from a thermal power plant or the like.

[0002]

For example, in a coal-fired power plant, fly ash (coal ash) is constantly discharged, and the amount of discharge is, for example, 60 tons per day per generator (about 100 to 120 tons). (Rice). Although a small portion of this fly ash is reused as a filler for cement or the like, most of the fly ash is treated as landfill for industrial waste.

However, disposal of fly ash as industrial waste requires a great deal of cost, and in recent years, problems such as shortage of industrial waste disposal sites, securing of resources, and environmental protection have become more serious. For this reason, even in the case of fly ash as described above, it is required that the ash be recycled as industrial resources, rather than landfilled, for effective use.

[0004] For example, sludge discharged from construction sites and the like and sludge discharged from general residual soil are generally sent to a treatment facility.
Gravel is separated and collected, and reused as aggregate for ready-mixed concrete. On the other hand, the remaining clay slurry is subjected to a filter press to remove water and discharged as cake-like solid clay. This solid clay has also been conventionally treated as industrial waste, and it has been desired to develop an effective recycling method.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fly ash processing method and a fly ash processing method capable of effectively recycling fly ash discharged from a coal-fired power plant or the like. Providing artificial soil.

[0006]

Means for Solving the Problems The present inventor repeatedly conducted tests and studies to effectively use fly ash (coal ash) discharged from a coal-fired power plant or the like, and as a result, obtained fly ash into waste mud. The present invention has been accomplished by confirming that it can be regenerated as soil in combination with solid clay obtained by the treatment and also treated as industrial waste. That is, fly ash and solid clay are used as main raw materials, and a stabilizing agent and a pH adjuster are added thereto, followed by stirring and mixing, so that artificial soil (artificial sand) usable for various applications can be regenerated. You can.

At this time, the stabilizing agent improves the soil quality by a physical and chemical reaction, and has a role of aggregating the fine particles of fly ash and clay and consolidating the particles to develop strength. Fulfill. As this kind of stabilizing agent, quick lime, cement-based solidifying agent and the like can be used. And, as it is, the pH of the artificial soil is extremely high (pH is about 14) and is highly alkaline, so that it cannot withstand actual use. be able to. As this kind of pH adjuster, an acidic material such as aluminum sulfate, iron sulfate, and sulfur can be used.

In addition, when the water content of the main raw material is small, the reaction by the stabilizing agent is not sufficiently performed, so that it is necessary to add water to secure a predetermined water content. Furthermore, not only fly ash and solid clay, but also those containing sand and gravel, such as muddy soil and good-quality earth and sand, can be mixed as a main raw material, whereby an artificial soil with higher strength can be obtained. In the above-mentioned stirring and mixing process, a stirring and mixing machine equipped with an impeller and the like is used.
It is desirable to perform sufficient stirring and mixing.

Incidentally, the above-mentioned pH adjuster is relatively expensive, and there are circumstances in which the amount of addition must be increased in order to lower the pH in a relatively short time. The present inventor has further studied that, by introducing exhaust gas of an engine such as a diesel engine into the agitated part, it is possible to reduce the amount of the PH adjuster used, while reducing the pH of the artificial soil for a short time. It was confirmed that it was possible to reduce the cost effectively and to make it relatively inexpensive.
This is presumed to be because carbon dioxide, nitrogen oxides, sulfur oxides, and the like in the exhaust gas act as a pH adjuster. It is needless to say that the power of the engine can be used for various purposes.

[0010] The artificial soil according to the present invention can be used for various purposes. For example, it is a backfill material for embedding work such as embankment, a water pipe or a gas pipe, a road work such as a roadbed material or a subgrade material, a material for embankment and seawall, a material for reclamation, and the like. In this case, an artificial soil suitable for use can be obtained by appropriately changing the mixing ratio of fly ash, solid clay, muddy soil, high quality earth and sand, and the like. In addition, this artificial soil is a mixture of particles of various particle sizes. By separating fine particles having a small particle size, artificial sand can be obtained as a substitute for mountain sand or river sand.

[0011] In addition, since the above-mentioned artificial soil contains almost no organic matter or microorganisms, it is difficult to grow plants when used as it is, and it is not suitable for use as soil for agriculture or embankment for landscaping. Not suitable for Therefore, if the artificial soil is made to contain microorganisms suitable for the growth of plants, it can be made suitable for agriculture and horticulture. In this case, it is desirable to add in the form of an organic fertilizer such as a natural compost containing microorganisms.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIG. 1 shows a process of processing fly ash according to the present embodiment, that is, a process of manufacturing artificial soil, and FIG. 2 shows a schematic configuration of a processing facility 1 used to execute the processing process. Is shown. First, fly ash A shown in FIG. 1 is discharged from, for example, a coal-fired power plant, and has, for example, a component composition and the like shown in Table 1 below.

[0013]

[Table 1]

The fly ash A is carried, for example, by a truck or the like, and is accumulated in the fly ash accumulation section 2 of the processing equipment 1 shown in FIG. At this time, generally,
To facilitate transportation, water is sprayed on the fly ash A. The fly ash A contains, for example, about 50% of water. Although not shown, a roof is entirely provided above the processing equipment 1 so that rainwater or the like does not enter.

On the other hand, for example, when excavation of the ground is performed at a construction site or the like, sludge B, such as sludge and general remaining soil, is discharged. The sludge B, which has been confirmed by the dissolution test to be free of harmful substances such as cadmium, total cyanide, and organic phosphorus compounds, is transported to a sludge treatment facility adjacent to the treatment facility 1 and treated as follows. Is performed.

That is, the muddy soil B is first sent to the trommel 3 where it is separated and removed from the gravel C having a relatively large particle size while being washed with water, and then sent to the classifier 4 to be washed with water and further washed with water. The relatively small sand D is separated and removed.
Then, the remaining muddy water is sent to the thickener 5 to perform a constant dehydration process. Finally, the remaining slurry-like clay slurry is sent to a filter press device 6, which is also partially shown in FIG. 2, where it is filtered under pressure to form cake-like solid clay E. The above-mentioned gravel C and sand D are classified into respective grades according to, for example, particle size, and are used as aggregate of ready-mixed concrete. In the above process, the water used for washing is recycled and used repeatedly.

The solid clay E obtained by the above process is stored in the solid clay accumulating section 7 shown in FIG. The solid clay accumulating section 7 may be provided with a high quality such as sludge, general waste soil, etc., sludge, mountain sand, the above-mentioned gravel B, sand C, etc., if necessary (depending on the intended use of the artificial soil to be obtained). Sediment F and organic fertilizer G are stored. As the organic fertilizer G, for example, a soil conditioner "Ecosoil" (trade name) manufactured by Suzuki Co., Ltd. is used. It is composted by adding microorganisms (VS34). Therefore, the organic fertilizer G contains a large amount of microorganisms such as bacteria suitable for growing plants.

Now, as shown in FIG. 2, the processing equipment 1
The fly ash accumulation unit 2 and the solid clay accumulation unit 7 are provided on the right side in the drawing. A stirring mixer 8 as shown in FIG. 1 is arranged on the left side thereof, and each device is arranged around the stirring mixer 8 as described later. I have.

The stirrer-mixer 8 is called a stabilizer, and as shown in FIGS. 3 and 4, is placed on a base 9 in the left-right direction in FIG.
m), and the mixing chamber 10 is provided with an inlet 10a at the upper surface of the left end in the drawing and an outlet 10b at the lower part of the right end in the drawing. ing. In the mixing chamber 10, two shafts 1
1 are rotatably provided, and a plurality of impellers 12 protruding in a radial direction are attached to the shafts 11. The two shafts 11 are rotated by a motor 13 and a transmission mechanism 14 provided on the base 9. Thus, the material input from the input port 10a is sent to the discharge port 10b side while being stirred and mixed by the rotation of the impeller 12.

As shown in FIG. 2, the hopper 15 into which the fly ash A of the fly ash accumulating section 2 is charged and the fly ash in the hopper 15 are located on the right side in the view of the stirring mixer 8. A to the stirring mixer 8
A screw conveyer 16 is provided for feeding the solid clay E and the like from the solid clay accumulating unit 7 and the solid clay E and the like in the hopper 17 are fed to the stirring mixer 8. A screw conveyor 18 for feeding to the inlet 10a is provided.

On the upper side in FIG. 2 of the stirring and mixing machine 8, a tank 19 containing the cement-based hardening agent H (see FIG. 1) and the cement-based hardening agent H in the tank 19 are supplied to the stirring and mixing machine 8. Screw conveyor 20 to be sent to the inlet 10a
And a screw conveyor 22 for feeding the quicklime I in the tank 21 to the inlet 10a of the stirring mixer 8 and a tank 21 for accommodating quicklime I (see FIG. 1).
Is provided.

The cement-based solidifying agent H and quicklime I are:
It functions as a stabilizing agent, and in this example,
As the cement-based solidifying agent H, "Stabilite" (trade name) manufactured by Mitsubishi Mining Cement Co., Ltd. is used. The "stabilite" solidifies and stabilizes the soil by the generation of ettringite, and contains calcium oxide as a main component and silicon dioxide, aluminum oxide, sulfur trioxide, ferric oxide and the like.

On the left side of the stirring mixer 8 in FIG.
The tank 23 containing the adjusting agent J (see FIG. 1) and the pH adjusting agent J in the tank 23 are supplied to the inlet 10 of the stirring mixer 8.
There is provided a screw conveyor 24 for feeding to a. The pH adjuster J is for lowering the pH of an alkaline material to neutrality, and uses, for example, an agent mainly containing aluminum sulfate. Further, a water tank 25 for storing the water K (see FIG. 1) and a water injection mechanism 26 such as a pump for sending the water K in the water tank 25 to the inlet 10a of the stirring mixer 8 are also provided.

On the lower side of the stirring mixer 8 in FIG. 2, a pit 27 for containing a product (artificial soil described later) is provided. Although illustration and detailed description are omitted, the number of rotations of the motors of the screw conveyors 16, 18, 20, 22, and 24, in other words, the feed amount of the material per unit time is as follows.
It can be freely set by microcomputer control. Similarly, the amount of water injected by the water injection mechanism 26 can be freely set.

Further, in this embodiment, a generator room 28 is provided at the side of the filter press device 6, and an engine (displacement of 8000 cc) is provided therein.
A generator driven by a large-sized diesel engine (10000 to 10000 cc) is provided. Then, the exhaust gas L (see FIG. 1) discharged from the engine is introduced into the mixing chamber 10 of the agitating mixer 8 through an exhaust gas introduction pipe 29 partially shown in FIGS. Has become. Thus, the exhaust gas L is blown to the agitated material in the agitating mixer 8.

As shown in FIG. 1, the main raw materials such as the fly ash A and the solid clay E, the cement-based solidifying agent H
The stabilizing agent consisting of lime and quicklime I, and the pH adjuster J are sent to the stirring mixer 8 at a predetermined ratio, where the stirring and mixing process is performed. Further, at this time, as described above, the exhaust gas L is introduced into the mixing chamber 10 of the stirring mixer 8, and further, necessary water is supplied. As a result, these materials are sufficiently stirred and mixed in the stirring mixer 8.

Thus, the fine particles of fly ash A and solid clay E are agglomerated by the action of cement-based solidifying agent H and quick lime I, and the particles are consolidated to exhibit strength. You get it. In particular, fly ash A is highly alkaline (for example, when PH is 1
4), it will not be able to withstand actual use as it is.
H is 8.6 or less), and an artificial soil M having no problem can be obtained.

In this case, in this embodiment, in the process of stirring and mixing, the exhaust gas L of the diesel engine is blown against the agitated material.
While reducing the amount of adjuster J used, the P of artificial soil M
It has been confirmed that H can be effectively reduced in a short time. This is presumed to be because carbon dioxide, nitrogen oxides, sulfur oxides, and the like in the exhaust gas L act as a pH adjuster.

The mixing ratio of each of the above-mentioned materials can be appropriately set according to the use and purpose of the artificial soil M to be obtained. As an example, the artificial soil M in which the fly ash A is 100, the solid clay E is almost the same amount (100), the cement-based solidifying agent H is 10, and the PH adjuster J is 0.1 It can be used for embankment. In addition, by mixing the organic fertilizer G, an artificial soil M suitable for agriculture and horticulture can be obtained.

FIG. 5 shows an example in which the artificial soil M is used for landscaping embankment. The artificial soil M (without the organic fertilizer G) is piled on the ground O in a small mountain shape. An artificial soil M (shown by changing the direction of hatching) containing an organic fertilizer G is arranged on the (surface layer). And landscaping is performed by performing tree planting P, sowing, and the like on the surface layer. According to this, the plant is grown on the surface layer portion containing microorganisms such as bacteria, and the bottom portion, which is not so related to the growth of the plant, does not contain the organic fertilizer G and can be manufactured at low cost.

Further, since the artificial soil M is used for road works such as backfilling materials and roadbed materials and for embankment works, when relatively high strength is required, together with the solid clay E, the muddy soil is used. B, gravel C, sand D, and high-quality earth and sand F may be blended.
The artificial soil M is a mixture of particles having various particle sizes. By separating fine particles having a small particle size from the artificial soil M, artificial sand N as a substitute for mountain sand and river sand (see FIG. 1)
See also).

Next, the artificial soil M obtained as described above
The usefulness of artificial sand N will be described with some test results. The following Table 2 shows the soil test results of the artificial soil M and the artificial sand N in this example. Among them, the compaction test and the water permeability test were performed only on the artificial sand N. The table also shows the results of the CBR test. FIG. 6 shows the artificial soil M
(A) and the particle size accumulation curve of the artificial sand N (b) are shown respectively.

[0033]

[Table 2]

As is apparent from the results, in the present embodiment, the artificial soil M and the artificial sand N which can sufficiently withstand use.
was gotten. In addition, a sufficient CBR value can be obtained,
Excellent strength was also obtained. Therefore, the artificial soil M can be used for various types of materials such as embankment, backfilling material for burying works such as water pipes and gas pipes, road construction such as roadbed materials and subgrade materials, embankment and seawall materials, and landfill materials. Available for use,
Also, the artificial sand N can be sufficiently used as a substitute for mountain sand or the like.

The applicant has established a test farm using the artificial soil M (comprising organic fertilizer G and containing microorganisms suitable for plant growth) and produced crops (radish and kabura).
Was grown. The following Table 3 shows the results of a component test of the collected radish and scab.

[0036]

[Table 3]

As apparent from Table 3, the artificial soil M
Has no harmful substances and is well suited for plant growth. Therefore, the artificial soil M is
In addition to the above-mentioned landscaping, the soil can be sufficiently used as agricultural soil. The pH of the artificial soil M and the artificial sand N is omitted, but is assumed to be neutral and cause no problem.

As described above, according to the present embodiment, fly ash A, which has been conventionally difficult to reuse, is replaced with artificial soil M
It became possible to reproduce as. In addition, it was confirmed that the artificial soil M (and the artificial sand N) can be used for various uses. Therefore, fly ash A and solid clay E, which were conventionally mostly treated as industrial waste,
Can be effectively reused (recycled) as industrial resources, and can greatly contribute to solving problems of securing resources and environmental protection.

Further, in the process for treating fly ash A to obtain artificial soil M, fly ash A and solid clay E are used as main raw materials, and stabilizing agents H, I and P are used.
It is relatively simple and inexpensive, such as adding and stirring and mixing other materials such as H adjuster J. In this case, in this embodiment, in particular, by introducing an exhaust gas from the engine, the P of the artificial soil M is improved.
Since H is effectively reduced, it is possible to reduce PH in a short time while slightly reducing the amount of expensive PH adjuster J used.

Further, the artificial soil M of the present embodiment can be made sufficiently high in strength by mixing waste soil B, high quality earth and sand F, and the like.
Further, by adding an organic fertilizer G containing a microorganism suitable for growing a plant, the organic fertilizer G can be made suitable for landscaping and agricultural use.

[0041]

As is apparent from the above description, according to the present invention, a fly ash is mixed with a solid clay obtained by treating sludge, and a stabilizing agent and a pH adjuster are added. By stirring and mixing, it has become possible to obtain artificial soil that can be used for various purposes. As a result, fly ash can be effectively reused as industrial resources.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a view schematically showing a processing step of fly ash.

FIG. 2 is a plan view schematically showing a configuration of a processing facility.

FIG. 3 is a plan view showing the stirring mixer with a part cut away.

FIG. 4 is a side view showing the stirring mixer with a part cut away.

FIG. 5 is a longitudinal sectional view showing a state in which artificial soil is used for landscaping.

FIG. 6: Particle size accumulation curve of artificial soil and artificial sand

[Explanation of symbols]

In the drawing, 1 is a processing facility, 2 is a fly ash accumulation unit, 6
Is a filter press device, 7 is a solid clay collecting section, 8 is a stirring mixer, 15, 17 is a hopper, 16, 18, 20, and
22, 24 are screw conveyors, 19, 21, 23
Is a tank, 25 is a water tank, 26 is a water injection mechanism, 29 is an exhaust gas introduction pipe, A is fly ash, B is waste mud,
E is solid clay, F is good-quality earth and sand, G is organic fertilizer, H is cement-based solidifying agent (stabilizing solidifying agent), I is quicklime (stabilizing solidifying agent), J is PH adjuster, K is water, and L is exhaust gas. , M indicates artificial soil and N indicates artificial sand.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C09K 17/42 C09K 17/50 H 17/50 B09B 3/00 301M // C09K 101: 00 304G

Claims (5)

[Claims] 1. A fly ash mixed with a solid clay obtained by treating muddy soil, a stabilizing agent and a PH.
A method for treating fly ash, wherein an artificial soil is obtained by adding a regulator, stirring and mixing. 2. The fly ash processing method according to claim 1, wherein an exhaust gas of an engine is introduced into the agitated material in the agitation and mixing processes. 3. An artificial soil obtained by using fly ash and solid clay obtained by treating muddy soil as main raw materials, and adding a stabilizing agent and a pH adjuster thereto. 4. The artificial soil according to claim 3, wherein said main raw material is mixed with muddy soil or high-quality earth and sand. 5. The artificial soil according to claim 3, further comprising a microorganism suitable for growing a plant.