JP4441715B2 - Method for producing coal ash slurry material for ground material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a coal ash slurry material that is effectively used as a construction material by combining coal ash, which is a waste having a low utilization rate, and electric furnace reducing slag.
[0002]
[Prior art]
Although industrial waste disposal is becoming a social problem, effective use of industrial waste is required, but high-priced products are not marketable and difficult to use compared to current competitive products. Yes.
Although ground materials are considered as an application that uses a large amount of industrial waste, conventional products of ground materials become low-priced sand and gravel, so that new products that can counter this are made. Was difficult.
[0003]
Among industrial wastes, coal ash is a relatively safe waste, and since it emits nearly 10 million tons annually in Japan, it is positioned as a large amount of waste, but its utilization rate is 50 %, Which is low compared to blast furnace slag.
Therefore, about 9 to 25% cement is added to coal ash to make a slurry, and the utilization rate has been increased as a ground material. The cost was high due to high costs, and it was not possible to compete in price compared to sand and gravel. And depending on the kind of coal ash, since a compressive strength of several MPa is expressed by adding a small amount of cement, it may be difficult to utilize as a ground material.
In addition, electric furnace reduced slag is generated in steel slag more than 600,000 tons per year, and its amount tends to increase. However, since it is not self-hardening like cement, it is prone to expansion failure and is almost used. It wasn't.
[0004]
[Problems to be solved by the invention]
In view of the above situation, the present invention is intended to solve the problem, and by combining industrial wastes with low utilization rates together, a high quality and inexpensive coal ash slurry material suitable for the ground material is obtained. The manufacturing method of the coal ash slurry material which can be supplied is made into the subject.
[0005]
[Means for Solving the Problems]
In the method for producing a coal ash slurry material according to the present invention, an electric furnace reducing slag corresponding to 1 to 100% of the mass of coal ash is added to coal ash to prepare a mixture, and water is added to this to mix and slurry. In order to develop strength, water is added in two stages, or electric furnace reducing slag is crushed to a particle size comparable to that of coal ash to increase strength. By adding bentonite or carboxymethyl cellulose corresponding to 1 to 5% of the ash, the coal ash slurry material is easily manufactured.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing a coal ash slurry material according to the present invention, an electric furnace reducing slag corresponding to 1 to 100% of the mass of coal ash is added to coal ash to prepare a mixture, and water is added to this to mix and slurry. Embodiments will be described below with reference to the drawings.
[0007]
FIG. 1 shows a process for producing a coal ash slurry material according to the present invention.
In the figure, reference numeral 1 denotes a mixer such as a Nauta mixer, etc., in which a predetermined amount of coal ash and electric furnace reducing slag pulverized to a particle size comparable to that of coal ash by a method described later are added to perform component adjustment and mixing. Yes. Depending on the type of slurry mixer, the mixer 1 such as a Nauta mixer can be omitted.
When the addition rate of the electric furnace reducing slag is less than 1%, the strength as the coal ash slurry material becomes low, and when it exceeds 100%, it becomes difficult to form a slurry. The mass is from 1 to 100 mass, preferably from 2 to 50 mass, per 100 mass of coal ash.
That is, if it is less than 2%, a special mixing device is required to obtain a homogeneous slurry. On the other hand, if it exceeds 50%, a large amount of separation inhibitor is required to maintain the pumpability of the slurry.
[0008]
The component-adjusted / mixed coal ash is mounted on a container, conveyed, and transferred to the raw material hopper 2.
In the raw material hopper, a fixed amount belt feeder is operated, and a predetermined amount of coal ash mixture is fed into a mixing / mixing machine 3 such as a pug mill by a belt conveyor. The slurry material 5 having a predetermined fluidity is mixed.
When the moisture added to the mixture is added in two portions without adding all the amounts at once, the density of the slurry can be increased, and the solidification strength of the slurry can be increased. Therefore, a more appropriate slurry is supplied by appropriately selecting according to the situation of the site where the slurry is used.
[0009]
With the above process, a general slurry material is completed, but depending on the type of coal ash and electric furnace reducing slag, the water retention is low, so there may be a problem of causing material separation when slurryed as it is. . In such a case, by using a mixer 4 such as a Henschel mixer as shown in the figure, 1-5% bentonite or carboxymethylcellulose is added as a binder to maintain slurrying, thereby separating the slurry material. Try to avoid.
[0010]
The electric furnace reducing slag added to the coal ash can use the powder product generated during the operation of the electric furnace as it is, but it needs to be mixed in a large amount because the strength expression is low when mixed with the coal ash.
In order to improve this, the particle size is adjusted to the same level as that of coal ash to increase the expression strength and to make it easy to slurry. In addition, in the case of the bulk electric furnace reducing slag, it cannot be used as it is, so the electric furnace reducing slag is pulverized, the particle size is adjusted to the same level as coal ash, the expression strength is increased, and the slurry It is made easy to convert.
[0011]
For this reason, the processing of the electric furnace reducing slag is performed as shown in FIG. 2 to facilitate the slurrying treatment with coal ash.
That is, the bulk electric furnace reducing slag is first put into a crusher 6 such as a jaw crusher, and then finely crushed and then sorted. Those having a large particle size are further rotated and subdivided by a roll crusher 7 and sorted into a predetermined size by a vibrating screen 8. The selected electric furnace reducing slag is further transferred to the ball mill 9 and pulverized to the same particle size as the coal ash.
[0012]
Next, the characteristics of the manufactured coal ash slurry material will be described.
The strength required when the slurry is used as the ground material varies slightly in each case, but the target value is usually set to a uniaxial compressive strength of 0.1 to 1 MPa.
This is because if the value of the uniaxial compressive strength exceeds 1 MPa, reexcavation becomes difficult, and if it is less than 0.1 MPa, the stability as the ground will be hindered.
In addition to this, how to select the slump value is also a problem in terms of pumping pressure, but in the measurement using a 15 cm slump cone, if it is around 11 cm, a normal pump can be used without preparing a slurry pump. Since the slurry can be pumped by using the above, the above value is set as the target value of the slump.
The coal ash slurry material manufactured by the manufacturing method according to the present invention expresses the strength corresponding to these target values, as shown in the examples described later, and can be effectively used as a ground material. It is in.
[0013]
In FIG. 3, the compounding example and physical property of the coal ash slurry material manufactured with the manufacturing method by this invention are summarized and displayed on the table | surface.
The coal ash slurry material of the example (1) group is made into a slurry by adding 2% powdered electric furnace reducing slag to 100% coal ash and mixing 30-40% water thereto. In the coal ash slurry material of Example (2) group, 2-6% of powdered electric furnace reducing slag is added to 100% of coal ash, and 40% of water is mixed with this. Manufactured similarly.
In addition, in order to compare with these Examples, the comparative example which mixed the blast furnace slag cement B seed | species in coal ash with the different quantity is also shown simultaneously.
[0014]
[Example 1]
The physical properties of the coal ash slurry material (1) group are shown as test results of C-1, C-4, and C-7 in Table-1 of FIG.
As shown in the test results in Table-1, when the amount of water added to the coal ash is changed and the amount of water mixed is changed, the stage of the material age is 7 days corresponding to the amount of water mixed. , The uniaxial compressive strength of 0.3 to 0.5 MPa is expressed, and the uniaxial compressive strength of 0.6 to 0.9 MPa is expressed on the material age 28th.
The fluidity shows a value of 6.5 to 13 cm at a 15 cm slump value. In the case of mixing with 30% water, the target value of 11 cm is not reached. Even when judged in combination with the above-mentioned uniaxial compressive strength values, it shows characteristics that can be sufficiently used as a ground material.
[0015]
[Example 2]
The physical properties of the coal ash slurry material (2) group are shown as test results of C-7, C-8, and C-9 in Table-1 of FIG.
As shown in the test results in Table 1, when the amount of water added to the coal ash was changed to make the amount of water constant, 7 days In the stage, the uniaxial compressive strength of 0.3 to 0.8 MPa is expressed, and the uniaxial compressive strength of 0.6 to 1.4 MPa is expressed on the 28th day of the material age.
The fluidity is a slump value of 15 cm, each of which is a value of 13 cm or more and exceeds the target value. When judged together with the numerical value of the uniaxial compressive strength, the fluidity is the same as in Example (1) group. In addition, it shows the characteristics that can be sufficiently used as a ground material.
[0016]
On the other hand, when blast furnace slag cement B type is mixed with coal ash, B-1 and C-1 in Table-1 are used even if the addition amount and the mixing amount of water are the same as those of the electric furnace reducing slag. As shown in the physical property values of B-9 and C-9, the slump value shows almost the same value, but the uniaxial compressive strength is a value exceeding 1 MPa in any example. Since it is manifested and it is clear that re-excavation is difficult as described above, it is not suitable for use as a ground material.
[0017]
From the above situation, the addition rate of the electric furnace reducing slag to the coal ash can be adopted in the range of 1 to 100% from the viewpoint of the strength expression as the coal ash slurry material, but preferably the addition rate is in the range of 2 to 50%. Is preferred. And when it exceeds 50%, a measure for improving water retention by adding bentonite or carboxymethylcellulose is necessary, and in this case, the range of 1 to 5% is desirable.
[0018]
As described above, the present invention is based on the addition of water to a mixture obtained by adding electric furnace reducing slag corresponding to 1 to 100% of the coal ash mass to the coal ash and mixing it into a slurry. Water is added in two stages, or electric furnace reducing slag is added after being pulverized to a particle size similar to that of coal ash to achieve strength, which corresponds to 1-5% of coal ash in the mixture The addition of bentonite and carboxymethylcellulose facilitates the production of coal ash slurry materials, so the construction of ground materials, etc., by combining coal ash and electric furnace reducing slag together with low-utilization industrial wastes. High quality and inexpensive coal ash slurry material suitable for materials can be supplied.
[0019]
As described above, the present invention has been described in detail based on the embodiment. However, the method for producing the coal ash slurry material according to the present invention is not limited to the above embodiment, and the above-described purpose of the present invention is not limited. Naturally, various changes can be made without departing from the scope.
[0020]
【The invention's effect】
In the method for producing a coal ash slurry material according to the present invention, an electric furnace reducing slag corresponding to 1 to 100% of the mass of coal ash is added to coal ash to prepare a mixture, and water is added to this to mix and slurry. It is easy to manufacture coal ash slurry material, and by combining industrial wastes with low utilization rate, such as coal ash and electric furnace reduction slag, Since the desired uniaxial compressive strength and desired slump value are expressed, it has the effect of improving the quality so that it can be effectively used as a ground material and supplying an inexpensive coal ash slurry material. Yes.
[0021]
In addition, water is added in two stages, or electric furnace reducing slag is crushed to the same particle size as coal ash and added to increase strength. If necessary, coal ash is added to the mixture. By adding bentonite or carboxymethyl cellulose corresponding to 1 to 5% of the above, it is easy to make a slurry and maintains the slurry state by avoiding material separation, and also has the effect of improving the production efficiency and characteristics of the coal ash slurry material ing.
[Brief description of the drawings]
[Fig. 1] Manufacturing process diagram of coal ash slurry material according to the present invention [Fig. 2] Process diagram of electric furnace reducing slag pulverization processing [Fig. 3] Physical property diagram of coal ash slurry material according to the present invention [Explanation of symbols]
1 Mixer, 2 Raw material hopper, 3 Mixer / Mixer, 4 Mixer,
5 Coal ash slurry material, 6 Jaw crusher,
7 Roll crusher, 8 Vibrating sieve, 9 Ball mill,

Claims (4)

It is characterized by adding water to the mixture added to the coal ash after pulverizing the electric furnace reduced slag corresponding to 1 to 100% of the mass of the coal ash to the same particle size as the coal ash, and mixing it into a slurry. A method for producing a coal ash slurry material for ground materials . The method for producing a coal ash slurry material for ground material according to claim 1, wherein moisture is added in two stages. Bentonite is added to a mixture , The manufacturing method of the coal ash slurry material for ground materials of Claim 1 or Claim 2 characterized by the above-mentioned . Carboxymethylcellulose is added to a mixture , The manufacturing method of the coal ash slurry material for ground materials of Claim 1 or Claim 2 characterized by the above-mentioned .

Images