JP2018051475A - Production method of coal ash granular material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a coal ash granular material using a pan type pelletizer, hardly needing the modification of the pan type pelletizer and continuously producing the coal ash granular material having uniform grain sizes.SOLUTION: In a production method of a coal ash granular material,: coal ash and a binder of 20-70 pts.mass to 100 pts.mass coal ash are kneaded; a kneaded material is charged into a pan type pelletizer charged with pulverizing balls and pelletized; and the binder is made of one or more kinds of solid binders desirably selected from among portland cement, mixed cement, economy cement, quick-setting cement, bentonite and a kaolin mineral and water.SELECTED DRAWING: None

Description

  The present invention relates to a method for continuously producing a granular coal ash material having a uniform particle size.

  Coal ash generated from coal-fired power plants can be used as a roadbed material if it is solidified by adding cement and water to a granular material in addition to its use as a concrete admixture or cement admixture utilizing pozzolanic reactivity. It can also be used as an aggregate.

  Here, as a method for granulating coal ash, the method for producing coal ash sand described in Patent Document 1 adds cement and water to coal ash, and mixes and granulates at high speed using a Henschel mixer, Eirich mixer, or the like. Is the method. However, the particle size of the coal ash sand obtained by this method is as small as about 3 mm or less, and the productivity is low because the manufacturing method is a batch method.

  By the way, there is a bread-type pelletizer as an apparatus that can continuously produce granular particles of powder, but the particle size of the coal ash granular material continuously produced using this apparatus is about 5 to 30 mm and varies. large.

In the production of a granular material using a pan-type pelletizer, several methods for aligning the particle diameter have been proposed. For example,
In the method for producing coal ash sand described in Patent Document 2, a rotary blade that collides with falling powder is provided in a region where the powder on the rotating pan falls, and powder scattered by collision with the rotating blade collides. A bread granulator provided with a fixed plate is used.
The manufacturing method of the granulation raw material for sintering described in Patent Document 3 includes a mixing step of adding moisture to the blended raw material and mixing with a drum mixer, and a granulation step of granulating the blended raw material after mixing with a pan pelletizer Is a method of producing a granulated raw material for sintering, and is a method of crushing and producing a blended raw material containing coarse particles between the mixing step and the granulating step.
The method for producing a granulating raw material for sintering described in Patent Document 4 is based on the type of the crushing blade, the number of revolutions, and the pressing force depending on the particle size of the blended raw material that rolls in a swirling manner in the pan pelletizer. Etc. are adjusted and pulverized according to the particle diameter, and subsequently re-granulated in the pan pelletizer to produce pseudo particles having a relatively uniform particle size in a desirable form as a granulation raw material for sintering. It is a manufacturing method.
In the method for producing a granulating raw material for sintering described in Patent Document 5, coarse pseudo particles in the rolling layer of the blended raw material staying in the pan pelletizer are removed from the wall surface scraper and / or the bottom surface scraper in the pan pelletizer. It is the method of manufacturing by re-granulating to the size of an appropriate particle, crushing at the same time with the scraping function with a crushing function.
Moreover, the manufacturing method of the granulation raw material for sintering described in Patent Document 6 includes coarse pseudo particles in the rolling layer of the blended raw material staying in the pan pelletizer, and a plurality of pulverized teeth protruding. It is a method of manufacturing by re-granulating to the appropriate particle size while crushing with a pair of crushing rolls rotating in opposite directions.

JP 61-155102 A JP-A-2-251408 JP 2014-201763 A JP 2014-227568 A JP 2014-234545 A Japanese Patent Laying-Open No. 2015-54980

  However, all of the methods of Patent Documents 2 to 6 are low in versatility due to the large scale modification of the pan-type pelletizer.

  Accordingly, the present invention provides a method for producing a coal ash granular material using a pan-type pelletizer, which does not require modification of the bread-type pelletizer and continuously produces a coal ash granular material having a uniform particle size. The purpose is to do.

Therefore, as a result of intensive studies on the manufacturing method, the present inventor continuously puts a mixture of coal ash and a binder mixed in advance into a bread-type pelletizer in which pulverized balls having a predetermined particle diameter are placed in a pan. Thus, the inventors have found that the above-mentioned problems can be achieved, and completed the present invention.
That is, this invention is a manufacturing method of the coal ash granular material which has the following structure.

[1] After kneading coal ash and 20 to 70 parts by mass of a binder with respect to 100 parts by mass of the coal ash, the kneaded product is put into a pan-type pelletizer in which pulverized balls are placed in a pan. A method for producing a granular coal ash material.
[2] The coal ash according to [1], wherein the binder is composed of at least one solid binder selected from Portland cement, mixed cement, ecocement, fast-setting cement, bentonite, and kaolin mineral and water. A method for producing a granular material.
[3] The method for producing a coal ash granular material according to [1] or [2], wherein a mixing amount of the solid binder is 5 to 30 parts by mass with respect to 100 parts by mass of coal ash.
[4] The coal ash granular form according to any one of [1] to [3], wherein the amount of water mixed is 12 to 38 parts by mass with respect to 100 parts by mass in total of the coal ash and the solid binder. A method of manufacturing the material.
[5] The method for producing a coal ash granular material according to any one of [1] to [4], wherein the amount of the pulverized ball used is 25 to 100 parts by mass with respect to 100 parts by mass of the kneaded product.
[6] The method for producing a coal ash granular material according to any one of [1] to [5], wherein the kneaded product is continuously or intermittently charged into a bread-type pelletizer.
[7] The method for producing a coal ash granular material according to any one of [1] to [6], wherein the particle size of the coal ash granular material is adjusted by the particle diameter of the pulverized ball and the amount of the pulverized ball used.

The method for producing a coal ash granule according to the present invention can continuously produce a coal ash granule having a uniform particle size using a general-purpose pan pelletizer without remodeling the pan pelletizer. Therefore, according to the manufacturing method of the coal ash granular material of this invention, the coal ash granular material of a predetermined particle diameter can be manufactured simply and in large quantities, and utilization of coal ash can be promoted.
Moreover, the manufacturing method of the coal ash granular material of this invention is applicable also to granulation of the powder material other than coal ash.

  As described above, the method for producing a coal ash granular material according to the present invention, after kneading coal ash and a specific amount of a binder, the kneaded product is produced using a pan-type pelletizer in which a pulverized ball is placed in a pan. It is the method of granulating and manufacturing a coal ash granular material.

  The coal ash granular material of the present invention can be easily made into a powder that can exhibit the pozzolanic reactivity originally possessed by coal ash (powder) by pulverizing the coal ash granular material when the mixing amount of the binder is small. Can be returned. Moreover, if the mixing amount of a binder is increased, the crushing strength of a coal ash granular material can be raised, and after performing predetermined curing, it can be used as a roadbed material or an aggregate. Furthermore, when the coal ash granular material of the present invention is fired at a temperature of around 1000 ° C., a coal ash granular material with higher crushing strength is obtained.

  The coal ash used in the present invention is not limited to the fly ash specified in JIS A 6201 “Fly ash for concrete”, as long as it can be granulated with a pan-type pelletizer. Absent.

  The binder used in the present invention includes Portland cement, mixed cement, eco-cement, quick-hardening cement, bentonite, and kaolin mineral (hereinafter, generic name) from the viewpoint of handling and crushing strength development of a mixture of coal ash and binder. And so on) and at least one selected from water and the like. Among these solid binders, from the standpoint of developing the crushing strength of the coal ash granular material, it is preferably at least one selected from Portland cement, mixed cement, ecocement, and fast-setting cement, more preferably One or more types selected from early-strength Portland cement, ordinary Portland cement, eco-cement, and fast-curing cement.

  The mixing amount of the solid binder is preferably 5 to 30 parts by mass, more preferably 7 to 20 parts by mass, and still more preferably 10 to 15 parts by mass with respect to 100 parts by mass of coal ash. When the mixing amount of the solid binder is less than 5 parts by mass, the crushing strength of the coal ash granular material is not sufficient, and when it exceeds 30 parts by mass, the mixing amount of the coal ash decreases, which is not preferable from the viewpoint of promoting the use of coal ash. .

  As water used in the present invention, tap water, water other than tap water, and recovered water specified in JIS A 5308 “Ready mixed concrete” Annex C can be used.

  The mixing amount of water is 15 to 40 parts by mass, preferably 15 to 30 parts by mass, and more preferably 15 to 25 parts by mass with respect to 100 parts by mass of coal ash. If the mixing amount of water is less than 15 parts by mass or exceeds 40 parts by mass, the spherical formability of the coal ash granular material is inferior and the expression of the crushing strength is not sufficient.

  Moreover, the amount of the water mixed is preferably 12 to 38 parts by mass, more preferably 15 to 30 parts by mass, and still more preferably 15 to 25 parts by mass with respect to 100 parts by mass in total of the coal ash and the solid binder. .

For kneading coal ash and binder, general-purpose kneading devices such as wheel type, ball type, blade type, roll type, etc. can be used, and among these, it is possible to cope with a wide range of moisture content of the kneaded material, preferably A blade-type kneading device such as a paddle mixer. As will be described later, in order to continuously produce the coal ash granular material, the coal ash and binder kneaded material is homogeneous so that the coal ash and binder kneaded material can be continuously supplied to the pan-type pelletizer. Knead until
The kneading time until homogenization is preferably 1 minute or more in low-speed kneading using a Hobart mixer (A-200 manufactured by Hobart Japan Co., Ltd.) of 10 kg of kneaded material (rotation speed of the agitator is 107 rpm). More preferably, it is 2 minutes or more.

  In the bread of the bread type pelletizer used in the present invention, a pulverized ball is placed before the kneaded product is charged. The material of the pulverized ball is not particularly limited, and ceramic balls such as alumina and zirconia, and steel balls such as chrome steel can be used.

  In the present invention, the particle size of the coal ash granular material can be controlled by the particle size of the pulverized ball used. For example, to produce a coal ash granular material having a particle size of 0.3 to 5 mm as described later, A pulverized ball having a diameter of 20 to 50 mm may be used. This is because the coal ash granular material jumps when colliding with a grinding ball that freely moves in a rotating pan, or escapes between the grinding balls or between the grinding balls and the pan, It is presumed that the particle size of the coal ash granular material that can grow grains without directly receiving the impact due to the collision of the particle size depends on the particle size of the pulverized balls used.

  Further, pulverized balls having different particle diameters may be used at the same time. As will be described later, when a pulverized ball having a small particle diameter is used in combination, the effect of suppressing an increase in the diameter of the granulated product (coal ash granular material) is higher than when only a pulverized ball having the same diameter is used.

  The amount of the pulverized balls used is preferably 2.5 to 10 kg with respect to 10 kg of the coal ash and binder kneaded product when a bread-type pelletizer having a pan with an inner diameter of 60 cm and a depth of 15 cm is rotated at 22 rpm. . If the amount of the pulverized balls used is less than the above range, the large-diameter granulated product will increase, and if it exceeds the above range, the excessively small-diameter granulated product will increase and the productivity will decrease. In addition, the usage-amount of the said grinding | pulverization ball is 3-8 kg more preferably with respect to 10 kg of kneaded materials of coal ash and a binder. The amount ratio of the kneaded material and the pulverized ball may be appropriately adjusted according to the size of the bread-type pelletizer to be used and the operating conditions.

  In order to continuously produce a coal ash granular material, a kneaded product of coal ash and a binder is continuously fed into a pan of a pan-type pelletizer or intermittently at predetermined time intervals. In order to stabilize the production state, continuous charging is preferable. A general mechanical transport device such as a belt conveyor or a screw conveyor can be used for charging the kneaded product of coal ash and binder.

  The speed at which the kneaded product of the coal ash and the binder is put into the pan of the pan-type pelletizer is, for example, a pan-type pelletizer having a pan with an inner diameter of 60 cm and a depth of 15 cm on which 2 kg of crushed balls having a particle size of 40 mm are placed When rotating at 22 rpm, 5 kg of coal ash and binder kneaded material is put into the pan in advance at the start, and new coal ash and binder kneaded material is added thereto at a charging rate of 500 g / min. Thus, a continuous production state of 500 g / min can be realized.

  Even if the coal ash granular material manufactured using the present invention is piled up immediately after manufacturing, adhesion between particles does not occur. The obtained coal ash granular material is preferably cured in order to promote the strength development by the binder, but there is no limitation on the curing method, and it can be cured in the air such as by leaving it in a place where it can be prevented from getting wet. It is enough.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
1. Materials used (1) Coal ash (FA)
The coal ash used has a density of 2.40 g / cm ³ , a brain specific surface area of 2920 cm ² / g, and a 45 μm sieve residue of 18.8% by mass. In addition, Table 1 shows the chemical analysis results based on JIS R 5204 “Method for fluorescent X-ray analysis of cement”.
(2) Binder The binder used is a mixture of ordinary Portland cement (OPC, Taiheiyo Cement) and tap water. In addition, the chemical composition measured according to JIS R 5204 “Fluorescence X-ray analysis method of cement” of the used ordinary Portland cement is shown in Table 1, and according to JIS R 5201 “Physical test method of cement”. Table 2 shows the measured physical property values.

2. Kneading coal ash and binder 5 kg of the coal ash, 500 g of ordinary Portland cement, and 1 L of tap water are put into a Hobart mixer (A-200 manufactured by Hobart Japan Co.), and the speed is low (the rotational speed of the agitator is 107 rpm). For 1 minute.

3. Manufacture of coal ash granular material The above kneading is carried out on a bread-type pelletizer (pan: inner diameter 60 cm × depth 15 cm, angle 48 °, rotational direction counterclockwise, rotational speed 22 rpm) on which the pulverized balls (iron balls) of Table 3 are placed The coal ash granular material was continuously produced by replenishing the intermittent raw material, in which 6.5 kg of the material was added in advance to start granulation, and then 6.5 kg of the kneaded material was charged at intervals of 15 minutes.
The results obtained by sieving the coal ash granular material of each level of 25 kg obtained by continuous production for about 1 hour using a sieve specified in JIS Z 8801 “Sieving for Testing-Part 1: Metal Net Sieve”. Table 4 shows.

As shown in Table 4, according to the production method of the present invention, it is understood that a coal ash granular material having a uniform particle size can be produced continuously, even though the pan-type pelletizer is not modified.
Moreover, about the 2.36 mm sieve residue of Example 5, the drop strength of the drop strength test of five drop operations performed according to JIS Z 8841 “Granulated material—Strength test method” is as good as 92.1%. Met.

Claims (7)

  After kneading coal ash and 20 to 70 parts by mass of binder with respect to 100 parts by mass of coal ash, the kneaded product is put into a pan-type pelletizer in which a pulverized ball is placed in a pan and granulated. Coal ash granular material manufacturing method.   The coal ash granular material according to claim 1, wherein the binder comprises at least one solid binder selected from Portland cement, mixed cement, ecocement, fast-setting cement, bentonite, and kaolin mineral and water. Method.   The manufacturing method of the coal ash granular material of Claim 1 or 2 whose mixing amount of the said solid binder is 5-30 mass parts with respect to 100 mass parts of coal ash.   The method for producing a coal ash granular material according to any one of claims 1 to 3, wherein the mixed amount of water is 12 to 38 parts by mass with respect to 100 parts by mass in total of the coal ash and the solid binder. .   The manufacturing method of the coal ash granular material of any one of Claims 1-4 whose usage-amount of the said grinding | pulverization ball is 25-100 mass parts with respect to 100 mass parts of said kneaded materials.   The method for producing a coal ash granular material according to any one of claims 1 to 5, wherein the kneaded product is continuously or intermittently charged into a bread-type pelletizer. The manufacturing method of the coal ash granular material of any one of Claims 1-6 which adjusts the particle size of a coal ash granular material with the particle size of a grinding ball and the usage-amount of a grinding ball.