JPH02251408A - Manufacture of coal ash sand - Google Patents

Abstract

PURPOSE:To continuously manufacture a sand-like fine aggregate by providing a rotating blade in an area where powder on a rotating pan is dropped and feeding mixed powder of coal ash, cement and water into a pan-type granulator provided with a fixed plate to which the powder being scattered by the rotating plate is fed. CONSTITUTION:Powder fed into a pan 1 of a rotating pan type granulator is dropped onto the pan 1 to form a powder retention area 2 in a corner of lower right and also a powder transfer line of arrow mark C in the area 2. The powder picked up from the powder retention area 2 follows a powder transfer line of mark D and drops onto the pan 1 to be concentratively dropped on an area 3. A rotating blade 4 rotating in the direction of mark E is provided in the area 3. A fixed plate 5 to which the powder being scattered by the rotating blade 4 is hit is installed taking an interval with the upper surface of the pan 1 in a manner that the powder to be hit is not accumulated in the vicinity of the fixed plate 5 but joined the powder flow in the pan 1. Said fixed plate 5 not only functions to form core particles but hits the rotating blade 4 and returns and collects the powder to be likely to scatter out the pan 1 back into the pan 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing coal ash sand suitable for use as a raw material for building materials, etc.

(Prior art) A method for artificially producing sand used as a raw material for building materials using coal ash as a raw material was disclosed in Japanese Patent Application Laid-Open No. 81-151052.
No. 1 proposes a method for producing coal ash sand, which is characterized in that cement and water are added to coal ash, and the mixture is mixed and granulated at high speed using a Henschel mixer, an Eirich mixer, or the like. Also known is a method of granulating a mixture of coal ash, cement, and water using a pan-type granulator, as described in the same publication.

(Problems to be Solved by the Invention) With the method using the Henschel mixer, Eirich mixer, etc., fine aggregate such as sand can be produced with a size of 3 mm or less, approximately 0.3 mm, but it requires batch granulation, which reduces productivity. low.

In addition, when using a pan-type granulator, continuous granulation is possible and production efficiency can be increased;
A gravel-like coarse aggregate of 31 or less, 0.
It is not possible to manufacture fine aggregate such as sand with a diameter of about 3 mm.

The present invention provides a method for producing coal ash sand that can continuously produce fine aggregate such as sand of 3II11 or less and about 0.3 mm.

(Means for Solving the Problems) The method for producing coal ash sand of the present invention includes providing a rotary blade that collides with the falling powder in an area on a rotary pan where the powder falls, and This method is characterized by supplying a mixed powder of coal ash, cement, and water to a pan-type granulator equipped with a fixed plate against which the flying powder collides.

(Function) The mixed powder of coal ash, cement, and water has a powder content of 300 pm or less, 98% or more of 150 pm or less, and an average diameter of several tens of tons, and there are few core particles that become nuclei when calculating numbers. Conventional pan-type granulators do not have the ability to generate core particles from the supplied raw materials, and because they hardly generate core particles, more powder adheres to the core particles, resulting in coarse particles.

Since it is impossible to change the particle size composition of the raw material, it is possible to add a function to generate core particles to the pan-type granulator and generate a large number of new core particles from the supplied raw material, which will improve grain growth. can be suppressed to obtain fine granules.

Focusing on this point, the present inventors added a function to generate core particles to a pan-type granulator, and as a result of intensive study on a method of generating a large number of new core particles from the supplied raw material. , a pan-type granulator is equipped with a rotating blade that collides with the falling powder in the area where the powder falls on the rotating pan, and a fixed plate that collides with the powder that is scattered by the collision with the rotating blade. It was confirmed that by supplying a mixed powder of coal ash, cement, and water, a large number of core particles were generated and the grain growth that occurs in conventional pan-type granulators was suppressed.

This is because aggregates with a coarsely packed structure consisting of a mixed powder of coal ash, cement, and water change into aggregates with a densely packed structure due to collisions with rotating blades and fixed plates, and as a result, the aggregates are difficult to deform. It is thought that the particles did not become adhered powder but instead began to behave as core particles.

An embodiment of a pan-type granulator used in the method of the present invention will be described below with reference to the drawings.

FIG. 1 shows, for example, the behavior of powder in the pan l of a pan-type granulator rotating in the direction of the arrow (counterclockwise) and the rotating blades.
This figure shows the arrangement position of the fixing plate. Powder supplied into the pan 1 along the path of arrow B falls on the pan 1, and a powder retention area 2 is formed at the lower right corner. In region 2, a powder movement path as shown by arrow C is formed.

On the other hand, the powder pulled up from the powder retention area 2 falls on the pan 1 along the powder movement path shown by the arrow.
The present invention focuses on the area 3 where the powder falls concentratedly in the area 3 indicated by the broken line.
A rotary blade 4 that rotates in the direction of arrow E (clockwise) is provided inside, and the powder falling on the bread 1 in the direction of the arrow is efficiently collided with the rotary blade 4.

The wider the rotation range of the rotary blade 4, the better the collision with the falling powder on the single-rotation pan 1, which is preferable from the viewpoint of nuclear particle generation, and the higher the circumferential speed of the single-rotation blade 4, the stronger the collision force with the powder.

As shown in FIG. 2, the rotating blades 4 are arranged at predetermined intervals in the longitudinal direction of a rotating shaft 7 having a flange 6 at its upper end.
A number of cross-shaped arms 8 are mounted perpendicularly to the shaft axis 7, and as shown in FIG. It is installed. The lowermost cross-shaped arm 8 is disposed with a slight gap from the top surface of the pan 1.

The powder that collides with the rotary blade 4 is scattered as shown by arrow F in FIG. In order to prevent the powder from accumulating near the fixing plate 5 and to ride the flow of the powder inside the pan 1, it is provided with a gap from the upper surface of the pan 1 as shown in FIG. In addition to the function of generating the core particles, the fixed plate 5 also has a function of trapping powder inside the pan 1 that collides with the rotary blade 4 and tends to fly out of the pan 1.

An electric motor 9 and a fixed plate 5, to which the flange 6 of the rotary blade 4 is attached and rotationally driven, are tilted in conjunction with the tilting of the pan 1 by a support mechanism 10.

(Example) 80 wt% of coal ash having a particle size distribution as shown in Table 1 and 20 wt% of ordinary Portland cement were mixed, and water was added to give an inner multiplier of 32% of the weight of the mixed powder. 5
Mixed with a Star Mixer for about a minute.

As shown in FIG. 1, a rotary blade 4 is provided in the area where the powder falls on the pan 1 for one revolution to collide with the falling powder, and the powder scattered by the collision with the rotary blade 4 collides with the mixed powder. A fixing plate 5 is provided.

The mixture was supplied to a 1 mφ pan-shaped granulator along the route indicated by arrow B.

The feeding rate of the mixed powder was 0.57/h, the pan angle was 50°, the pan rotation speed was 21 rp (North rotation speed: 0.57), the arm length was 240 am (1), and the rotation speed of the rotary blade 4 was 90 Orpm.

Granulation was performed at 1500 rpm.

To prevent adhesion between particles, the granulated product was dried on the surface of the particles at 20°C for one day, and then cured in a container at 80°C and 80% humidity to develop strength with cement. It was dried and the particle size distribution was measured, and the results are shown in FIG.

As is clear from Figure 3, the number of rotations of the rotating blade is 90.
In the case of Orpm, the ratio of 0.3 to 3s shoes is 65% and the number of revolutions of the blade per rotation is 150.
The ratio of mm is 75%, and the ratio of 0.3 mm or less is reduced by 10% compared to the case of 900 rpm.

When the rotating blade was removed and the above mixed powder was granulated under the above operating conditions, the mixed powder supplied at 0.5 T/h was discharged as it was, and 0.3 mm or less was 100%, making it difficult to granulate to the desired particle size. could not. Also, the feeding speed of the mixed powder is O,
When changing to Q5τ8, granules of 5 to ioms were obtained, and the above feed rate was less than 0.57/h, 0.05T/h
A mixture of the supplied mixed powder and the granulated material having a layer of 5 to 10 m was obtained in the range of 5 to 10 m.

(Effect of the invention) As described above, according to the method for producing coal ash sand of the present invention:
It is possible to continuously produce fine aggregate such as sand with a diameter of 31 mm or less and a diameter of about 0.3 mm.

Table 1

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of an embodiment of a pan-type granulator used in the method of the present invention, and FIG. 3 is an explanatory diagram of the particle size distribution of a granulated product continuously produced by the method of the present invention. 1. Pan of e-pan type granulator, 2ΦΦ fist powder retention area,
3φ... Powder concentrated falling area, 4... Rotating blade, 5・φ
・Fixed plate, 6...Φ flange, 7... Rotating shaft,
8 - Cross-shaped arm, 9... Electric motor, 10... Support mechanism.

Claims (1)

[Claims] Coal ash and A method for producing coal ash sand characterized by supplying a mixed powder of cement and water.