JPH0734855B2 - Manufacturing method of coal ash sand - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing coal ash sand suitable for use as a raw material for building materials and the like.

(Prior Art) As a method of artificially producing sand used as a raw material for building materials from coal ash as a raw material, JP-A-61-151052 discloses that cement and water are added to the coal ash, a Henschel mixer, There has been proposed a method for producing coal ash sand, which is characterized by high-speed mixing and granulation with an Eirich mixer or the like. Also known is a method of granulating a mixture of coal ash, cement and water with a pan-type granulator as described in the publication.

(Problems to be Solved by the Invention) With the method using the above-mentioned Henschel mixer, Eirich mixer, etc., fine aggregates such as sand having a size of 3 mm or less and about 0.3 mm can be produced, but the productivity is low due to batch granulation. .

In addition, when using a pan-type granulator, continuous granulation can be performed and production efficiency can be increased, but coarse aggregates such as gravel with a particle size of 5 mm or more and about 25 mm are manufactured, and 3 mm or less, about 0.3 mm. Unable to produce fine aggregate like sand.

The present invention provides a method for producing coal ash sand capable of continuously producing a fine aggregate such as sand having a size of 3 mm or less and about 0.3 mm.

(Means for Solving the Problem) In the method for producing coal ash sand of the present invention, a rotary blade that collides with falling powder is provided in a region where the powder falls on a rotary pan, and the rotary blade is provided with a cross-shaped arm. A plurality of stages are mounted so that the arms are orthogonal to the axis and the adjacent arms are staggered, and a fixed plate against which the scattered powder collides is provided at a position where the powder scatters due to the collision with the rotary vanes. It is characterized in that a mixed powder of coal ash, cement and water is continuously supplied little by little to a bread type granulator.

(Function) The mixed powder of coal ash, cement and water is 300μm or less, 150μ
m is 98% or more and has an average diameter of several tens of μm, there are few core particles that become cores during granulation, and conventional pan-type granulators function to generate core particles from the supplied raw materials. Since there are no particles and few core particles are produced, the amount of powder adhering to the core particles increases and the particles become coarse.

Since it is impossible to change the particle size composition of the raw material, a function to generate core particles is added to the pan-type granulator, and if a large number of core particles can be newly generated from the supplied raw material, grain growth will occur. It is possible to suppress and obtain fine granules.

Focusing on this point, the present inventors have added a function of generating core particles to a pan-type granulator, and as a result of extensive studies on a method of newly generating a large number of core particles from a supplied raw material. In the area where the powder on the rotary pan falls, a pan-type granulator provided with a rotary blade that collides with the falling powder and a rotary plate with which the powder scattered by the collision with the rotary blade collides, It was confirmed that by supplying the mixed powder of coal ash, cement and water, a large number of core particles were generated and the grain growth caused by the conventional bread type granulator was suppressed.

This is because the aggregate of coarse packing structure consisting of mixed powder of coal ash, cement, and water changes into the aggregate of dense packing structure due to the collision with the rotating blade and the fixed plate, and as a result, the aggregate does not easily deform. It is considered that the particles did not become adhered powder and exhibited behavior as core particles.

Hereinafter, an example of the bread granulator used in the method of the present invention will be described based on the ground.

FIG. 1 shows, for example, the behavior of the powder in the bread 1 of the bread granulator that rotates in the direction of arrow A (counterclockwise) and the rotating blade,
The arrangement position of the fixed plate is shown. The powder supplied into the pan 1 along the path of the arrow B drops on the pan 1 and the powder retention area 2 is formed at the lower right corner and In the area 2, a powder moving path as shown by an arrow C is formed.

On the other hand, the powder pulled up from the powder retention area 2 is indicated by the arrow D.
Take the powder movement path as shown in
It falls intensively in the area 3 shown by the broken line. The present invention is particularly applicable to such a powder falling area where the powder falls in a concentrated manner 3
A rotary blade 4 rotating in the direction of arrow E (clockwise) is provided therein, and the powder falling on the pan 1 in the direction of arrow D and the rotary blade 4 are efficiently collided.

The wider the rotation area of the rotary blade 4 is, the better the collision with the powder falling on the rotary pan 1 is, which is preferable for the generation of core particles, and the larger the peripheral speed of the rotary blade 4 is, the stronger the collision force with the powder is.

As shown in FIG. 2, the rotary vanes 4 are arranged at predetermined intervals in the longitudinal direction of a rotary shaft 7 having a flange 6 at the upper end.
The cross arms 8 are attached orthogonally to the shaft axis 7, and as shown in FIG. 1, the cross arms 8 adjacent to each other in the longitudinal direction of the shaft 7 are attached at different angles of 45 °. The lowermost cross-shaped arm 8 is arranged with a small gap from the upper surface of the pan 1.

The powder that has collided with the rotary blades 4 scatters as shown by the arrow F in FIG. 1. In the present invention, however, the powder that has scattered due to the collision with the rotary blades 4 collides with the fixed plate 5. As shown in FIG. 2, the upper surface of the pan 1 is spaced apart from the upper surface of the pan 1 so that the powder does not deposit near the fixed plate 5 and rides on the powder flow in the pan 1. In addition to the function of generating the core particles, the fixed plate 5 has a function of catching the powder, which collides with the rotary blade 4 and jumps out of the pan 1, into the pan 1.

The flange 6 of the rotary blade 4 is mounted, and the electric motor 9 and the fixed plate 5 that rotate and drive the rotary blade 4 are tilted by the support mechanism 10 in conjunction with the tilting of the pan 1.

(Example) 80 wt% of coal ash having a particle size distribution as shown in Table 1 was mixed with 20 wt% of ordinary Portland cement, and water was added so that the internal content was 32% of the mixed powder weight, Mix for about 5 minutes with a star mixer.

As shown in FIG. 1, this mixed powder is provided with a rotary blade 4 that collides with the falling powder in a region where the powder falls on the rotary pan 1, and the powder scattered by the collision with the rotary blade 4 collides with the powder. It was supplied to the 1 mφ bread type granulator provided with the fixing plate 5 by the route of arrow B.

Feed rate of mixed powder is 0.5T / h, pan angle is 50 °, pan rotation speed
21 rpm (specific rotation speed 0.57), rotary blade 4 with arm length 240 mm
Granulation was performed at 900 rpm and 1500 rpm.

In order to prevent the particles from adhering to each other, the granulated product was dried on the surface of the particles at 20 ° C. a day, and then cured in a container at 80 ° C. and 80% humidity to develop strength with cement. The results of measuring the particle size distribution after drying it are shown in FIG.

As is clear from FIG. 3, the rotation speed of the rotary blade is 900 rpm.
In the case of, the ratio of 0.3 to 3 mm is 65%, and the rotation speed of the rotary blade is
In the case of 1500 rpm, the ratio of 0.3 to 3 mm is 75%, and in the case of 900 rpm, the ratio of 0.3 mm or less is reduced by 10%.

When the rotary blade was removed and the above-mentioned mixed powder was granulated under the above-mentioned execution conditions, the mixed powder supplied at 0.5 T / h was discharged as it was, and 0.3 mm or less became 100%, and it was not possible to granulate to the target particle size. It was When the feed rate of the mixed powder was changed to 0.05 T / h, granules of 5-10 mm were obtained, and the feed rate was 0.5 T
less than 0.05m / h, 5-10m with the mixed powder supplied in the range of more than 0.05T / h
A mixture of m granules was obtained.

(Effect of the invention) As described above, according to the method for producing coal ash sand of the present invention, 3 m
It is possible to continuously produce fine aggregate such as sand having a size of m or less and about 0.3 mm.

[Brief description of drawings]

FIG. 1 and FIG. 2 are explanatory views of an example of a pan type granulator used in the method of the present invention, and FIG. 3 is an explanatory diagram of particle size distribution of granulated products continuously produced by the method of the present invention. 1 ... Bread of pan type granulator, 2 ... Powder retention area, 3 ...
… Powder concentrated falling area, 4 …… Rotating blades, 5 …… Rotating plate,
6 ... Flange, 7 ... Rotating shaft, 8 ... Cross arm, 9 ... Electric motor, 10 ... Support mechanism.

Claims (1)

[Claims] 1. A rotary blade for colliding with falling powder is provided in a region where powder falls on a rotary pan, and the rotary blade has a cross-shaped arm whose arms are orthogonal to an axis and adjacent arms are staggered. In a pan-type granulator provided with a fixed plate against which the scattered powder collides at a position where the powder scatters by collision with the rotary blade, coal ash, cement, and water. A method for producing coal ash sand, characterized by continuously supplying a small amount of mixed powder.