JPH11263658A - Production of granurated material containing coal ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a granulated material high in packing density and load strength by compaction and capable of being utilized for a material for construction and a building material in a conical type screw mixer. SOLUTION: A solid raw material composed of a coal ash, cement and a cement kiln dust is mixed with water in the conical type screw mixer and is finished into the granulated material in the mixer. It is preferable to use 50-95 pts.wt. coal ash, 2-25 pts.wt. cement and 3-45 pts.wt. cement kiln dust per 100 pts.wt. solid raw material. The granulating operation can be also automatized by detecting the granulating state from the change of load current value of a screw stirring shaft of the conical type screw mixer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a granulated material containing coal ash. More specifically, the present invention relates to a method for producing a coal ash-containing granule that can be used as a civil engineering material, a building material, and the like.

[0002]

2. Description of the Related Art In order to effectively use coal ash generated in large quantities from a coal-fired power plant, a method has been proposed in which granules used as civil engineering materials are artificially produced using coal ash as a raw material. I have. Japanese Patent Application Laid-Open No. 61-151052 discloses a method of producing coal ash sand by adding cement and water to coal ash and performing high-speed mixing and granulation. Similarly, Japanese Patent Application Laid-Open No. 63-201045 discloses a method of producing coal ash sand by adding cement and water to coal ash and slag powder and performing high-speed mixing and granulation. In addition, as a granulator capable of forming spherical granules suitable for civil engineering materials, bread molds,
Rolling granulator such as drum type, spiral, Erich,
A high-speed stirring granulator such as Henschel is known as a conventionally known technique. However, there is a problem with these granulators in that the granules can be easily produced in large quantities. In the tumbling granulator, it is necessary to monitor the granulation state inside the granulator during the granulation operation and adjust the addition amount of moisture or solid raw material appropriately, so that it is difficult to automate the equipment and obtain the granulation obtained. Since the product has a narrow particle size distribution and a spherical shape,
Compact density, compacted CBR test (Cali
fornia Bearing Ratio; JIS
A 1211) has a low load strength and is not suitable for civil engineering materials. On the other hand, the high-speed stirring granulator has a small change in the torque of the granulator corresponding to the transition of the grain growth and is difficult to automate, and the obtained granules have a relatively small grain size.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coal ash which can be used as a civil engineering material or a building material in a conical screw mixer known per se, which has a high filling density, a high load strength by compaction. It is to provide a method for producing a granulated product containing: Another object of the present invention is to provide a method for producing a granulated material, which can automate a series of operations from the input of the raw material of the granulated material to the discharge of the granulated material. Still other objects and advantages of the present invention will become apparent from the following description.

[0004]

According to the present invention, the above objects and advantages of the present invention are as follows: first, a solid raw material consisting of coal ash, cement and cement kiln dust and water are mixed in a conical screw mixer. And finishing in the mixer to a granulated product.

[0005] The mixing ratio of each component of the solid raw material is coal ash,
The coal ash is preferably 50 to 95 parts by weight, more preferably 60 to 90 parts by weight, particularly preferably 60 to 85 parts by weight, based on a total of 100 parts by weight of cement and cement kiln dust, and the cement is preferably 2-2
5 parts by weight, more preferably 5 to 20 parts by weight, and the cement kiln dust is preferably 3 to 45 parts by weight,
More preferably 5-35 parts by weight, particularly preferably 10-35 parts by weight
25 parts by weight.

[0006] When the amount of coal ash is less than 50 parts by weight, the effective utilization amount of coal ash decreases, which is not preferable. On the other hand, if it exceeds 95 parts by weight, the strength of the obtained coal ash granulated material is undesirably reduced. If the amount of cement is less than 2 parts by weight, the strength of the obtained coal ash granulated material is undesirably reduced. On the other hand, if it is more than 25 parts by weight, the production cost of the coal ash granules increases, which is not preferable.

[0007] If the amount of the cement kiln dust is less than 3 parts by weight, it is not preferable because the gap between the coal ash and the cement particles cannot be sufficiently filled. If the amount is more than 45 parts by weight, cement kiln dust protrudes from the gap between the coal ash and the cement particles, which is not preferable because it causes a reduction in the strength of the granulated material containing the coal ash.
As coal ash, any of pulverized coal combustion ash, fluidized bed combustion ash and the like can be used, but fluidized bed combustion ash can be particularly preferably used because a granulated product can be easily produced. These can be used alone or in combination of two or more.

The average particle size of the cement kiln dust is preferably 10 μm or less, more preferably 5 μm or less, particularly preferably 1 μm or less. Although it does not have hydraulic properties as cement, it is desirable to have hydraulic properties. If the average particle size is 10 μm or more, the size becomes equal to or larger than the particles of coal ash and cement, and it is difficult to fill the gap between these particles, which is not preferable. Although the amount of water used for granulation varies depending on the type and particle size of the solid raw material, water is usually in the range of 25 to 45 parts by weight per 100 parts by weight of the solid raw material.

In the method of the present invention, not only the mixing of the solid raw materials but also the formation of granules is carried out in the conical screw mixer. Conical screw mixers are known per se and consist of a conical body with a conical end pointing downwards and a screw stirring shaft located from above to below along the inner wall of the conical body. The screw stirring shaft is capable of revolving and rotating.

In order to carry out the process of the present invention, the conical screw mixer has a rotation speed of the screw stirring shaft of preferably 1 to 5 rpm and a rotation speed of preferably 40 rpm.
It is advantageous to operate at a rotation of ~ 200 rpm.
The screw agitating shaft rotates to rotate the content in the conical body from the bottom to the top, thereby promoting the mixing and granulation of the entire content by revolving. The torque applied to the screw stirring shaft can be known by detecting the load current of the stirring shaft.

According to the method of the present invention, by using a conical screw mixer as a granulator, firstly, the mixing state of solid raw materials such as coal ash and cement, and the start of granulation with the addition of water. A state change such as a state and a subsequent change in grain growth can be known in accordance with a load current value of the granulator, and therefore, a series of granulation operations can be automated. Due to the rotation and the scooping action of the screw stirring shaft being a mold, the movement trajectory of the granulated material is different according to the particle size, so that the granulation efficiency is high.
Sphericality is slightly inferior to rolling granulators such as bread granulators, etc. In addition, coarse granules or a part of product granules larger than a predetermined particle size are coarsely crushed to obtain solid raw materials. Can be supplied to the granulator as a part of the product, and the particle size distribution width of the product granulation can be adjusted, so the packing density is high, the load strength in the CBR test by compaction is high, and granulation suitable for civil engineering materials etc. Advantages are obtained such that a product can be manufactured.

[0012] The granulated product is cured in ordinary humid air or steam and then used as a civil engineering material. Hereinafter, the granulation method of the present invention will be described with reference to FIG.
An embodiment will be described with reference to FIG.

The solid raw materials of the coal ash (a), the cement (b) and the cement kiln dust (c) are respectively weighed (feeders) (1-a), (1-b), (1-c),
A predetermined amount is cut out via the transport line (2) and supplied to the raw material receiver (3). In addition to the solid raw materials of coal ash (a), cement (b) and cement kiln dust (c), seeds obtained by coarsely crushing a part of a coarse granulated product or a product granulated product having a particle size larger than a predetermined particle size. (D) may be used.

A predetermined amount of solid raw material supplied to the raw material hopper scale (4) from the raw material receiver (3) is supplied to a specific conical screw mixer (5-1) based on a granulation cycle designated in advance. Charged to any one of (5-2) and (5-3) (5). On the other hand, a predetermined amount of water proportional to the solid raw material measured by the raw material hopper scale (4) is supplied to the conical screw mixer (5) from a water supply line (6) via a flow meter (not shown). Then, the granulation operation starts.

A mixed state of solid raw materials such as coal ash and cement,
Changes in the state of granulation progressing in the conical screw mixer (5), such as the state of the start of granulation due to the addition of water and the transition of the subsequent grain growth, correspond to the load current value of the granulator. Then, it is input as a control signal for the granulation operation. When the granulated material is granulated to a predetermined particle size and the load current of the granulator reaches a preset value, the granulated material is automatically transferred from the conical screw mixer (5) to the granulated material. It is discharged to a receiver (7).

Subsequently, the granules are transferred from the granule receiver (7) to the storage site via the granule transporter (8), and on the surface of the granules, the powder receiver ( The dust dust (e) or coal ash (a) of the dust collector (10) supplied from 9) is coated to form a product granulated product. These series of batch granulation operations are based on charging and mixing of solid raw materials, granulation time in a granulator, and the like, and a plurality of conical screw mixers (5-
1, 5-2, 5-3) and is configured with an optimal cycle system.

[0017]

Embodiments of the present invention will be described below. A solid raw material of coal ash and cement having a mixing ratio shown in Table 1 was mixed with a conical screw mixer (effective volume: 100 liters;
m, rotation at 127 rpm) for 10 minutes, and then the amount of water shown in Table 1 was added to start granulation. Subsequently, after stirring and mixing for 40 minutes, a granulated product having a predetermined particle size was obtained. Fig. 2 shows the mixing state of the solid raw materials such as coal ash and cement, the state of the start of granulation with the addition of water, the transition of the subsequent grain growth, and the change in the load current value of the granulator during this time. Was. As can be seen from the figure, the current value increased remarkably at the same time as the addition of water, and as the agitation continued, the primary agglomeration and consolidation of the particles of the solid raw material caused floating water on the surface of the granulated material, leading to higher-order aggregation and consolidation Can be read. Table 2 shows the particle size distribution of the obtained granules and the results of the modified CBR test. The granulated material has a high load strength due to compaction and has properties that can be used as a roadbed material.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

According to the present invention, a series of granulation operations from the input of solid raw materials such as coal ash and cement and water to the discharge of product granules can be automated. A granulating apparatus in which the granulating operation is easy and labor saving can be configured. In addition, a single granulator can produce granules with a particle size distribution width, high packing density, high load strength in compaction CBR test,
It is possible to produce coal ash-based granules that can be used as civil engineering materials and the like.

[0021]

[Brief description of the drawings]

FIG. 1 is a flow sheet of one embodiment of the granulation method of the present invention.

FIG. 2 shows a change with time of a load current value of a conical screw mixer (granulator) in an example of the present invention.

[Explanation of symbols]

 A, B, C, D Raw material silo a Coal ash b Cement c Cement kiln dust d Seed e Dust dust 1-a Coal ash feeder 1-b Cement feeder 1-c Cement kiln duster 1-d Seed feeder 1-e Dust dust or coal ash feeder 2 Transport line 3 Raw material receiver 4 Raw material hopper scale 5, 5-1 5-2, 5-3 Conical screw mixer 6 Water supply line 7 Granulated material receiver 8 Granule transporter 9 Powder receiver 10 Dust collector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyoaki Oshiro 1008 Awa, Nago City, Okinawa Prefecture Inside the Yabe Plant of the Ryukyu Cement Co., Ltd. Inside Kosan Co., Ltd. (72) Inventor Kuniaki Nitta 5 Ube Kosan, 1978 Ogushi, Ube City, Yamaguchi Prefecture Inside (72) Inventor Takao Wada 5 Ube Kogushi, 1978 Kodaigushi, Ube City, Yamaguchi Prefecture

Claims (4)

[Claims] 1. A coal ash, comprising mixing a coal ash, a solid raw material comprising cement and cement kiln dust and water in a conical screw mixer and finishing the mixture into granules in the mixer. A method for producing a granulated product comprising: 2. Coal ash 50 per 100 parts by weight of solid raw material
The method of claim 1 wherein the amount is from about 95 parts by weight, from 2 to 25 parts by weight cement, and from 3 to 45 parts by weight cement cement. 3. Water 25 to 100 parts by weight of solid raw material
The method of claim 1 wherein the amount is 45 parts by weight. 4. The granulation operation is automated by detecting a granulation state from a change in a load current value of a screw stirring shaft of the conical screw mixer.
the method of.