JPH09249446A - Production of coal ash reclaimed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize coal ash, etc., by blending the coal ash with a specific carbide, clay and water, kneading the resultant blend, molding the kneaded blend and then calcining the formed molding product. SOLUTION: A composition is obtained by blending 5-50wt.% of a coal ash with 10-30wt.% of a waste tire and/or a carbonization residue carbide of a combustible dust, 5-15wt.% of a carbonization residue carbide of a papermaking sludge and 15-40wt.% of a clay. Water in an amount of 25-35wt.% is then added to the composition and the resultant mixture is molded and then calcined at 500-700%oC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a useful recycled material by using a large amount of coal ash generated from a thermal power plant as a raw material.

[0002]

2. Description of the Related Art In a thermal power plant, coal is burned to obtain electric energy. The coal burning method is a pulverized coal burning method in which coal is pulverized and burned at a high temperature and lumpy or crushed limestone. There is a fluidized bed combustion method in which massive coal is burned in a fluidized bed. Conventionally, the pulverized coal combustion method has been the mainstream, but in recent years, regulations on NOx and SOx have become stricter. Therefore, attention has been paid to a fluidized bed combustion method which can reduce NOx and SOx and has high thermal efficiency. There is.

However, both combustion methods inevitably generate a large amount of coal ash with combustion.

The coal ash produced by the pulverized coal combustion method is composed of unburned carbon (hereinafter abbreviated as "unburned C") and F.CaO.
JIS A
6201 is used as an admixture for fly ash cement, and the coarse-grained portion is used as a clay raw material for cement. In addition, a small part is mixed with clay powder or coal powder, granulated and fired to produce a lightweight aggregate, but most of it is landfilled.

On the other hand, the coal ash generated by the fluidized bed combustion method contains about 10 to 30 wt% of unburned C and about 10 of F · CaO.
Since it is as large as ~ 20 wt% and may contain gypsum, if it is mixed with cement, it will harden rapidly,
Further, when the water reducing agent is used during kneading, it is adsorbed to the unburned C first, which increases the amount of the water reducing agent used, resulting in a high cost. Moreover, when coal ash containing gypsum is used as a cement raw material, there is a problem that it adversely affects the production of clinker minerals. Therefore, most of the coal ash generated by the fluidized bed combustion method is also landfilled without being used. However, recently, it has become difficult to secure landfill sites year by year, and effective treatment of coal ash is desired.

In recent years, the amount of waste tires generated has been increasing, and the disposal thereof has become a problem. Some of the scrap tires are
It is cut, frozen and crushed and recycled as raw material for recycled tires and rubber products. However, for the majority of waste tires, you must pay the processing cost to the cement company and use it as a supplementary fuel for burning cement, in whole or by cutting it, or collect gas and oil in a low-temperature carbonization furnace to burn cement. As an auxiliary fuel, or by blending the residual carbon-based material with the cement raw material to use as an energy source, SiO ₂ , A
There is also a method of using it as a source of l ₂ O ₃ .

Furthermore, about 75% of the combustible waste generated from ordinary households is incinerated at the incinerator, and the rest is landfilled as it is. After all, it is becoming increasingly difficult to secure landfill sites for household garbage. Further, the amount of combustion residue left after burning combustible industrial waste is also considerable. Since vinyl chloride dust is included in combustible waste such as household waste and industrial waste, hydrogen chloride gas is generated when these combustible waste are burned, and it is generated in the incinerator. There is a problem of damage to refractories and heat exchange pipes, and in addition, since heavy metals are contained in the incineration ash and fly ash of these dusts, in order to make them pollution-free, they must be melted and processed into glass. It is also considered to be used as an auxiliary fuel for cement burning or an auxiliary fuel for a thermal power plant as a solid fuel by separating it from the non-combustible materials and the method of making it into a solid fuel, but both methods are costly,
It is not a realistic method.

[0008]

[Problems to be Solved by the Invention] Coal ash, waste tires, and combustible waste tend to increase year by year, and it will become more and more difficult for the conventional treatment methods to deal with them in the future. In particular, securing landfill sites may be difficult in the future,
There is an urgent need for development of these treatment methods. The problem to be solved by the present invention is to provide a method for treating coal ash, waste tires and combustible waste to produce a useful coal ash recycled material.

[0009]

As a result of intensive studies to solve the above problems, the present inventor has noticed that coal ash has a porous property or contains unburned C,
It was found that a coal ash recycled material useful as a heat retaining material for steelmaking and a water retaining material can be produced by blending coal ash with carbides such as waste tires and dry distillation residue of combustible waste, and completes the present invention. Came to.

That is, (1) coal ash is mixed with at least one kind selected from waste tire carbonization residue carbonization, combustible waste carbonization residual carbonization and papermaking sludge carbonization residual carbonization and clay, and water is added. A method for producing a coal ash recycled material, which comprises kneading and molding, and then calcining (2) 10 to 50 wt% of coal ash, 5 to 15 wt% of carbonization residue of papermaking sludge carbonization residue, waste tire and / or flammability The method for producing a coal ash reclaimed material according to the above (1), wherein the carbonization residue of the waste carbonization residue is 10 to 30 wt% and the clay is 15 to 40 wt%. The present invention relates to a method for producing a coal ash reclaimed material according to item (1) or (2), which is a material, a water retention material, an adsorbent material, or a soil improvement material.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The coal ash as a raw material for the method of the present invention is not particularly limited as long as it is a coal ash generated from a thermal power plant or the like. Therefore, either coal ash generated by the pulverized coal combustion method or coal ash generated by the fluidized bed combustion method can be used, but the content of unburned C is higher in the coal ash generated by the fluidized bed combustion method. Because it is more porous,
Preference is given to coal ash generated by the pulverized coal combustion method.

[0012] In the method of the present invention, carbonization residue of waste tire dry distillation, carbonization residue of combustible waste dust or carbonization residue of papermaking sludge is carbonization of residue obtained by carbonization of waste tire, combustible waste or papermaking sludge. The dry distillation method is not particularly limited, but, for example, waste tires, combustible dust or papermaking sludge may be put in a dry distillation tank to obtain about 300 to 35.
After heating to 0 ° C and collecting gas and oil,
The temperature may be raised to 600 ° C. and kept for about 30 minutes. Dry distillation of waste tires, combustible waste or papermaking sludge distills gas and oil, and porous charcoal is obtained as a dry distillation residue. When the waste tire, the combustible dust or the papermaking sludge is subjected to dry distillation, it is preferable to dry the waste tire, the combustible dust or the papermaking sludge at about 100 ° C. in order to improve the efficiency of the dry distillation.

The combustible waste material used as the raw material for the carbonization residue carbon residue is not particularly limited as long as it is combustible waste such as general household waste, industrial waste, and municipal waste. It may include resin-made dust, paper, garbage, and the like.

The papermaking sludge is a sludge mainly composed of short fibers generated in the papermaking process, and a pulp sludge mainly composed of short fibers obtained by slurrying old newspaper or the like into water using an electric washing machine and dehydrating it. Is.

The clay used in the method of the present invention plays a role of a binder between coal ash and carbonization residue of carbonization residue, and examples thereof include clay such as bentonite mainly composed of montmorillonite.

To produce a coal ash reclaimed material according to the present invention, coal ash is blended with at least one selected from waste tire carbonization residue carbonization, combustible waste carbonization residue carbonization, and papermaking sludge carbonization residue carbonization. After adding water, kneading, shaping, and then calcining, coal ash, carbonization residue residue carbide and clay are mixed at a ratio of 10 to 50 wt.
%, At least one kind selected from carbonization residue of waste tire dry distillation residue, combustible waste carbonization residue carbonization and papermaking sludge carbonization residue carbonization, and clay 15-40%.
wt%, preferably 10 to 50 wt% coal ash
%, 5-15 wt% carbonization residue of papermaking sludge carbonization, 10 carbonization residue of waste tire and / or combustible waste carbonization residue
˜30 wt%, and clay is 15-40 wt%.

The method of molding by adding water to coal ash, carbonization residue of carbonization and clay is not particularly limited.
Examples thereof include a method of sprinkling water on a mixture of coal ash, carbonization residue of dry distillation residue and clay, or a method of kneading after water injection and molding into pellets by extrusion molding or press molding. Further, the amount of water to be added is not particularly limited as long as it can be molded, but is, for example, 25 with respect to the total amount of coal ash, carbonization residue of carbonization and clay.
About 35 wt% may be added.

A coal ash reclaimed material can be manufactured by calcining coal ash, carbonized carbon residue and clay, and then calcining, and the calcining temperature can be appropriately set within the range of 500 to 700 ° C. The calcination method is not particularly limited, but the calcination can be efficiently performed by using, for example, an electric furnace or a rotary kiln.

Since the recycled coal ash produced by the method of the present invention has a porous property, it can be effectively used as, for example, a heat insulating material for steelmaking, a water retaining material, an adsorbent or a soil improving material. .

When used as a heat insulating material for steelmaking of a coal ash recycled material produced by the method of the present invention, it can be put on molten slag to prevent a decrease in molten steel temperature, and steel such as pearlite, chaff, vermiculite, etc. It can be used as a substitute for heat insulating materials.

The coal ash recycled material produced by the method of the present invention is used as a water retaining material to mix the soil under the turf of a golf course with sand or the like, or the topsoil of an outdoor stadium such as an athletic stadium or a baseball stadium or an antoker. Underneath, mix with masa earth, or just 5-10
When it is laid down to a thickness of cm or is planted on a roadside tree, it can be mixed with masa soil to prevent the tree from withering in the summer, to prevent the amount of clay that becomes dust and to scatter, and to prevent irregular bounce. .

The recycled coal ash produced by the method of the present invention can adsorb pesticides and fertilizers well, and therefore can be effectively used as adsorbents for pesticides and fertilizers. When it is used as a soil improving material, it may be used for maintaining the water retaining capacity of Masa soil or volcanic ash soil and for neutralizing acidic soil.

[0023]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 A coal ash recycled material was produced by using coal ash having the properties shown in Table 1, carbonization residue of waste tire dry distillation residue, carbonization of combustible waste dry distillation residue, carbonization residue of papermaking sludge carbonization residue and clay. The coal ash in Table 1 is the product generated by the pulverized coal combustion method, and the coal ash is the product generated by the fluidized bed combustion method, and the carbonization residue of the dry distillation residue of waste tires, papermaking sludge and combustible waste was prepared as follows.

(Carbide of waste tire dry distillation residue) A steel radial tire for automobiles is cut into about 1/4, put in a dry distillation tank of about 200 L, heated to 300 to 350 ° C., gas and oil are recovered, and further 580 to 580. After heating to 600 ° C, about 30
After that, the steel component was cooled to room temperature, and the steel component was magnetically removed to obtain a carbide.

(Carbon Distillation of Paper Sludge) About 1 newspaper
Cut into quarters, put into an electric washing machine containing water in the same manner as in normal washing, rotate for about 20 minutes to make a slurry, dehydrate, and then rotary kiln (inner diameter 0.3 m x length 2. 9m, 8rpm, 5% inclining), about 200L
In a dry distillation tank, heated to 300 to 350 ° C to collect gas and oil, further heated to 580 to 600 ° C, and then heated to about 3
Hold for 0 minutes and then cool to room temperature to obtain a carbide.

(Carbide of dry distillation residue of combustible waste) City waste (vinyl, paper, plastic tray, vegetable scraps, etc.) is cut into about 15 to 20 cm with a cutter, and about 1/3 of water (about 140 to 150 L) is put therein. Put it in a drum-shaped container, scoop up what is floating in water to remove it, and then dehydrate it.
Dry for about 24 hours in a dryer kept at about 105 to 110 ° C, put in a dry distillation tank of about 200 L, and 300 to 350 ° C.
Heat to 50% to recover gas and oil, then 580-60
After the temperature was raised to 0 ° C., the temperature was maintained for about 30 minutes and then cooled to room temperature to obtain a carbide.

(Production of Recycled Coal Ash Material) Each raw material was put in a test pug mill at a blending ratio shown in Tables 2 and 3, and water was added (25 to 35 wt%) to mix, and insufficient water was sprinkled. While pan-type pelletizer (50cmφ × 10c
m, 18 to 20 rpm) and formed into pellets of about 5 to 20 mmφ. Then, it is dried in a dryer kept at 105 to 110 ° C. for 24 hours or more, and fired in a silicon knit electric furnace kept at about 600 to 650 ° C. for about 20 to 30 minutes, and cooled outside the furnace to regenerate coal ash. The wood was manufactured. The meltability, bulk specific gravity, specific heat and hygroscopicity of the obtained coal ash recycled material were measured. The results are also shown in Tables 2 and 3. In order to investigate the effect of the recycled coal ash as a heat insulating material for steelmaking, Table 4 shows the meltability, bulk specific gravity, specific heat and hygroscopicity of typical heat insulating materials for steelmaking.

The methods for measuring the meltability, bulk specific gravity, specific heat and hygroscopicity are shown below.

(Fusability) Each sample was put in a high alumina crucible and preheated at about 400 to 500 ° C. for about 10 minutes in an electric furnace, and further at 1250 ° C., 1400 ° C., 1550 in an electric furnace.
Each temperature was kept at 20 ° C. for 20 minutes, and the presence or absence of meltability was examined.

(Bulk Specific Gravity) The volume of the recycled coal ash material was measured by a graduated cylinder of 1000 ml, and the weight of the recycled coal ash material was measured.

(Specific heat) A coal ash recycled material was placed in a high alumina crucible and held in an electric furnace at 500 ° C for 10 minutes,
It was calculated from the amount of heat absorbed by water and the amount of heat released from the recycled coal ash at that time. (Hygroscopic) dryer (at 105-110 ° C for 24 hours or more)
After drying, put it in a plastic bag and weigh it, open the upper opening of the plastic bag and leave it for 7 days to measure the weight. Calculate the moisture absorption from the difference between the weight immediately after drying and the weight after standing for 7 days. It was

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

As is clear from the results shown in Tables 2 and 3, the recycled coal ash materials produced by the method of the present invention of Sample Nos. 1 to 23 are unmelted at 1400 ° C.
It was recognized that it is excellent as a heat insulating material for molten steel even at 0 ° C because it is sintered or unmelted (except for commercially available fir shells, it melts at 1400 ° C, and the fir shells themselves are difficult to obtain due to their reduced weight) . Recycled materials of sample number 24 to 27, which consist of coal ash alone or coal ash and clay only, have too large a bulk density or do not harden, generate a lot of dust, deteriorate the working environment, and have a small amount of C. Since it has a low heat retaining power, it was not suitable as a heat retaining material for molten steel.

The recycled coal ash produced by the method of the present invention has a slightly higher bulk specific gravity than conventional heat insulating materials for molten steel such as perlite and chaff, but does not scatter during use as perlite and chaff. It is preferable as a heat insulating material for molten steel.

[0039]

Industrial Applicability According to the method of the present invention, it is possible to produce a recycled material useful as a heat insulating material for molten steel, an adsorbent, etc. from coal ash, which is a large amount of industrial waste and has a problem of securing landfill disposal sites. In addition, waste tires, paper sludge, and combustible dust can be treated at the same time.

Claims (3)

[Claims] 1. A coal ash is blended with at least one selected from carbonization residue of waste tire dry distillation residue, carbonization of combustible waste dry distillation residue and carbonization residue of papermaking sludge dry distillation residue, and clay, and after adding water, kneading and molding, A method for producing a coal ash recycled material, which comprises firing. 2. Coal ash is 10 to 50 wt%, papermaking sludge carbonization residue carbon is 5 to 15 wt%, waste tire and / or
Or 10 to 30 wt% of carbonized residue of combustible waste carbonization residue,
And 15 to 40 wt% of clay, The method for producing a coal ash recycled material according to claim 1, wherein the clay is 15 to 40 wt%. 3. The method for producing a coal ash recycled material according to claim 1, wherein the coal ash recycled material is a heat insulating material for steelmaking, a water retaining material, an adsorbent material or a soil improving material.