JP3889818B2 - Method and apparatus for solidifying cement of fly ash - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method and an apparatus for solidifying cement generated from dust generated by incineration of general waste, that is, fly ash.
[0002]
[Prior art]
Conventionally, as a treatment method of fly ash, the Waste Disposal Journal (Vol.5, No.1) published in 1994 “Characterization of stabilized fly ash by solidification of cement” (pp.32-45) As described in (1), there are melt solidification, cement solidification, chemical treatment, and stabilization by oxygen other solvent, but the cement solidification method has become the mainstream.
[0003]
In this cement solidification method, cement is added to fly ash to obtain stabilized fly ash.
It is known that this cement solidification method includes rolling, compression, extrusion, pouring, etc. depending on the kneading and molding methods (as described in Urban and Waste Vol.12, No.2). (Refer to "Technical manual for ash fixation equipment").
[0004]
In general, a rolling or extruding method is used, and there are a drum type, a pan type, a vibration type (vibro type), a screw type, a roll type, a paddle type, and the like.
[0005]
[Problems to be solved by the invention]
However, in the conventional cement solidification system, in the case of drum type, pan type, and vibration type (vibro type), the particle size of the molded product can be obtained stably. The mixed state of water becomes unstable.
[0006]
Therefore, cement, fly ash and water are not uniformly mixed, only the surface of the molded product is solidified by cement, and the inside remains as fly ash and cement, so the strength of the molded product is weak, There was a problem that heavy metals such as lead were easily eluted during landfill.
In addition, in the case of screw type, roll type, paddle type, there is an advantage that kneading can be performed continuously, and the kneading state inside the molded product is better than the drum type and bread type, but the cement, fly ash, There is unevenness in the mixed state of water. However, there is a drawback that the shape of the molded product is not stable and it is difficult to discharge the semi-mixed product in the apparatus at the time of stopping.
[0007]
Accordingly, there are problems of strength of the molded product and elution of heavy metals such as lead at the time of landfill.
The present invention has been made in order to solve such conventional problems, and its purpose is excellent in mixing cement, fly ash, and water, making the quality of the granulated product uniform, and reducing the weight of heavy metals during landfill. It is an object of the present invention to provide a fly ash cement solidification method and an apparatus thereof that do not have a problem of dissolution.
[0008]
[Means for Solving the Problems]
The invention of claim 1 is a horizontal biaxial kneader having a plurality of stirring blades rotating in opposite directions to each other, and fly ash and 8 to 15% by weight of cement with respect to the fly ash in a dry state. A step of stirring and mixing while splashing, and a mist of 24 to 30% by weight of water with respect to the fly ash from above the fly ash and cement dispersed in the air while being stirred and mixed. In the step of spraying the water into a mist, the sprayed ash dispersed in the air and the cement are brought into contact with the mist of water, the fly ash and the cement While the water is contained in a small lump, it collides with other small lumps of fly ash and cement, and the lump with a larger particle size falls into the kneader and is further kneaded in the kneader. Repeat the operation to throw it into the air again. And, by this operation, and it is characterized in that the granulated product the mass of fly ash and cement, were molded from very small particulate to a predetermined 10～30Mmfai.
[0009]
According to a second aspect of the present invention, in the fly ash cement solidifying method according to the first aspect, the step of stirring and mixing and the step of spraying the water into a mist form stir and mix the fly ash and cement in a dry state. While continuing the process step 1 and stirring and mixing by the kneader, water is sprayed into the fly ash and cement that have been splashed and dispersed in the air in the form of mist, and the particle size is increased in the air. While repeating the step 2 of dropping into the kneader and releasing into the air, and after sprinkling, dropping to the kneader while increasing the particle size in the air by continuously stirring and mixing with the kneader. And step 3 which repeats the release to the air are operated in order .
Invention of Claim 3 is the cement solidification method of fly ash of Claim 2, characterized in that process step 1 is performed for about 1 minute, process step 2 is performed for about 2 minutes, and process step 3 is performed for 2 to 4 minutes. Is.
[0010]
According to a fourth aspect of the present invention, there is provided a fly ash cement solidifying apparatus used in the fly ash cement solidifying method according to any one of the first to third aspects, a fly ash container provided with a feeder, and a supply cement vessel with the machine, contact with the fly ash container and the cement container, a horizontal twin-screw having a plurality of stirring blades, as at the time of mixing a wet mixing step flipping the mixture It is characterized by comprising a kneader that automatically adjusts the rotational speed of the stirring shaft and a sprayer disposed above the kneader.
According to a fifth aspect of the present invention, there is provided a fly ash cement solidifying device used in the fly ash cement solidifying method according to any one of the first to third aspects, and a fly ash container provided with a feeder. A horizontal biaxial type having a plurality of stirring blades connected to a cement container equipped with a machine, the fly ash container and the cement container, so that the mixture jumps up during the mixing and humidification process. It is characterized by comprising a kneader for automatically adjusting the rotation speed of the stirring shaft, a sprayer disposed above the kneader, and a discharge conveyor located on the discharge side of the kneader. .
[0011]
[Action]
In the first to fifth aspects of the invention, first, fly ash and cement are mixed in a dry state, and then the mixture is spun up while continuing the mixing to disperse the fly ash and cement into particles in the air. Since each of the particles is sprayed with mist-like water over a predetermined time, it is possible to form a granulated product having a very small particle size to a predetermined 10-30 mmφ in a very uniform state.
[0013]
In addition, in the conventional method, it is said that the heavy metal elution value or less determined by the Director-General of the Environment Agency can be achieved by adding and fixing 13 to 40% by weight of cement and 18 to 40% by weight of water to fly ash. It was.
On the other hand, in the inventions of the first to fifth aspects, it is possible to make the amount below the reference value by adding 8 to 15% by weight of cement and 24 to 30% by weight of water.
[0014]
Therefore, when compared with the average value, the result is as follows. When the cement amount is 1/2 or less, the property of the solidified product is equal to or more than the same amount.
That is, in the cement ratio, conventionally, (13 + 40) /2=26.5%, and in the present invention, (8 + 15) /2=11.5%.
The amount of solidified product is 1 kg (fly ash) + 1 kg x 0.265 (cement) = 1.265 kg for 1 kg of fly ash (excluding water).
In the present invention, 1 kg (fly ash) +1 kg × 0.115 (cement) = 1.115 kg.
[0015]
As a result, the reduction rate of the solidified product is (1.265-1.115) ÷ 1.265 × 100≈12%.
In the inventions according to claims 1 to 5 , first, 8 to 15% by weight of cement is mixed in a dry state with respect to fly ash, and then the mixture is sprinkled up while continuing this mixing to bring fly ash and cement into the air. Since it is dispersed in particles and water is sprayed in the form of mist by dividing water into 30 to 30% by weight with respect to fly ash once or several times, it is molded from very small particles in a very uniform state. Is possible.
[0016]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a flow showing an embodiment of a fly ash cement solidification method according to claims 1 to 3 .
FIG. 2 shows an embodiment of the fly ash cement solidifying apparatus according to claims 4 and 5 .
[0017]
In FIG. 2, reference numeral 1 denotes a fly ash container comprising a dust hopper provided with a dust feeder 2 at the bottom.
Fly ash is supplied to the fly ash container 1 by means such as pneumatic transportation. A heater 3 is disposed below the fly ash container 1 to prevent condensation.
4 is a cement container comprising a cement hopper equipped with a cement feeder 5. Cement is supplied to the cement container 4 by means such as pneumatic transportation.
[0018]
A bag filter 23 is attached to the cement container 4.
Reference numeral 6 denotes a pipe line that communicates with the dust feeder 2 of the fly ash container 1, which joins the pipe line 7 that communicates with the cement feeder 5 of the cement container 4 and communicates with the service hopper 8.
The service hopper 8 is provided with a slide gate 9 at the bottom. A pipe line 10 for sending fly ash and cement to the horizontal biaxial kneader 13 communicates with the slide gate 9.
[0019]
The service hopper 8 communicates with a pipeline 11 for returning the cement to the cement container 4. This pipe line 11 is connected to a pipe line 12 that branches in the middle and communicates with a horizontal biaxial kneader 13.
A horizontal biaxial kneader 13 is provided with two paddle screws 14 having a plurality of stirring blades (paddles) 15.
[0020]
A plurality of sprayers 16 are disposed above the horizontal biaxial kneader 13.
The sprayer 16 communicates with the mixing water tank 17 through a pipe line 20 provided with a humidifying water pump 19. The mixing water tank 17 is provided with a stirrer 18 for mixing water and liquid chelate. The liquid chelate is added to react with heavy metals in the fly ash to make an insoluble heavy metal chelate compound when the fly ash and water are mixed. Since the liquid chelate is expensive, the amount of use thereof is reduced, and it is common to add 10 to 40% water and adjust the pH to the alkali side (pH 6 to 10). The addition rate of the liquid chelate is about 1 to 5%, and the liquid chelate reacts with metal ions such as Hg, Cd, Cu, Pb, Ni, Cu, Fe, etc., so the addition rate is affected by these contents. . Further, solidification with only water is possible without using a liquid chelate.
[0021]
A carry-out conveyor 21 is disposed on the discharge side of the horizontal biaxial kneader 13. The unloading conveyor 21 is configured to unload cement solidified material to the solidified material pit 22. Curing for about 30 minutes is performed on the carry-out conveyor 21.
Next, a fly ash cement solidification method using the fly ash cement solidification apparatus shown in FIG. 2 will be described based on the flow shown in FIG.
[0022]
First, fly ash and cement are supplied to the fly ash container 1 and the cement container 4, respectively.
Next, the dust feeder 2 and the cement feeder 5 are operated so that the cement is 8 to 15% by weight with respect to the fly ash, and is sent to the service hopper 8. Mix fly ash and cement amount using a level meter or light weight meter.
The service hopper 8, by operating the sliding gate 9 sends the fly ash and cement into the kneader 13 (step S1).
[0023]
Next, the kneader 13 stirs and mixes the fly ash and the cement in a dry state for about 1 minute (step S2).
At this time, the two paddle screws 14 rotate in opposite directions as indicated by arrows. Therefore, the fly ash and the cement are stirred and mixed while splashing up.
Next, while continuing the operation of stirring and mixing the fly ash and the cement in a dry state, the sprayer 16 is operated to mix the fly ash and the cement splashed up and dispersed into particles in the air, and the mixing water tank 17. The water inside is sprayed (step S3). In the dry state, the rotation speed during mixing and humidification mixing is automatically adjusted.
[0024]
This watering is performed for about 2 minutes.
At this time, fly ash and cement are very small particles in a very uniform state after being splashed into the air. while clash while becomes smaller chunks stick contain water will stick to other small chunks, the particle diameter increases, and falls into the mixing kneader 13, is further kneaded in the mixing kneader 13, hurled into the air again It is.
[0025]
Even after the watering is completed, the above operation is repeated for about 2 to 4 minutes. By this operation, the mass of fly ash and cement is molded from a very small granular shape to a predetermined 10 to 30 mmφ to obtain a granulated product (step S4).
Next, the mixing kneader 13 is stopped, to discharge the granulated product from the lower portion of the mixing kneader 13 to the conveyor 21 (step S5).
[0026]
The granulated material is sufficiently cured and solidified on the conveyor 21 (step S6).
Thereafter, it is buried in the solidified pit 22 (step S7).
As described above, according to this embodiment, a fly ash and cement were mixed in the dry state with mixed kneader 13, with continued stirring and mixing by the mixing kneader 13 flipped up the mixture fly ash and a cement dispersing the particles in the air, because the water spray atomized water from the sprayer 16 provided above the mixing kneader 13 over a predetermined time each particle, very while being extremely uniform It is possible to mold from a small particle to a predetermined granulated product of 10 to 30 mmφ.
[0027]
In addition, according to this example, the granulated product is molded by the kneader 13 and has a strength that could not be obtained by the conventional method, the variation in strength is very small, and the mixing ratio of fly ash and cement is stable. In addition, without using a chelating material, elution of heavy metals in a mixture of fly ash, cement, and water alone is reduced to a value (for example, elution of lead is 0.1 mg / l). I was able to.
[0028]
In the above embodiment, since it is a batch operation, when the kneading by the kneader 13 is started, the weight of the fly ash and the cement is started, and after the discharge of the granulated material from the kneader 13 is completed, to mixing kneader 13 can be continuously performed task of introducing a predetermined amount of fly ash and cement.
Therefore, no granulated product remains in the kneader 13 for each batch.
[0029]
【The invention's effect】
As described above, according to the inventions of claims 1 to 5 , the mixing of fly ash, cement and water is superior to the conventional method, the quality of the granulated material is uniform, and unprecedented strength is achieved. can get.
Further, since the cement is uniformly mixed, the problem of elution of heavy metals during the reclamation of the granulated material is eliminated.
[0030]
Furthermore, since it is a batch process, stable solidification can be achieved without difficult adjustments at the start of operation and at the time of operation stop. Moreover, since all discharge is performed from the lower part, no cement granule remains inside.
Furthermore, since the equipment can be operated with simple and simple operation, automation is easy.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an embodiment of a fly ash cement solidification method according to claims 1 to 3 ;
FIG. 2 is an explanatory view showing an embodiment of a fly ash cement solidifying apparatus according to claims 4 and 5 ;

Claims (5)

A step of stirring and mixing fly ash and 8 to 15% by weight of cement with respect to the fly ash in a dry state in a horizontal biaxial kneader having a plurality of stirring blades rotating in opposite directions. When,
A step of sprinkling water in the form of a mist of 24 to 30% by weight with respect to the fly ash from above the cement and the fly ash that is splashed and dispersed in the air while performing the stirring and mixing ,
In the step of spraying the water into a mist, the sprayed ash dispersed in the air and the cement are brought into contact with the mist of water, and the fly ash and the cement containing water are adhered to each other and are small. Repeat the operation of colliding with other small ash and cement while colliding with the mass while dropping the mass with a larger particle size into the kneader, further kneading in the kneader, and releasing it into the air again. By this operation, the fly ash cement solidification method is characterized in that the fly ash and cement are agglomerated from a very small granular shape to a predetermined 10 to 30 mmφ . The fly ash cement solidification method according to claim 1,
The step of stirring and mixing and the step of spraying the water into a mist form,
Process step 1 of stirring and mixing fly ash and cement in a dry state;
While continuing stirring and mixing by the kneader, water is sprayed into the fly ash and cement that are splashed up and dispersed in the form of particles in the air, and sprayed to the kneader while increasing the particle size in the air. Process step 2 which repeats the fall and release into the air,
Even after the sprinkling is finished, the process step 3 is sequentially operated in order to repeat the dropping to the kneader and the release into the air while continuing the stirring and mixing by the kneader to increase the particle size in the air. How to solidify fly ash cement. The fly ash cement solidification method according to claim 2,
A process for solidifying fly ash, comprising performing step 1 for about 1 minute, step 2 for about 2 minutes, and step 3 for 2 to 4 minutes . In the fly ash cement solidification apparatus used for the fly ash cement solidification method according to any one of claims 1 to 3 ,
A fly ash container with a feeder;
A cement container with a feeder,
Contact with the fly ash container and the cement container, a horizontal twin-screw having a plurality of stirring blades, automatically adjusts the rotation speed of the stirring axis as the time of mixing a wet mixing process flipping the mixture A kneading machine;
A fly ash cement solidifying apparatus comprising: a sprayer disposed above the kneader. In the fly ash cement solidification apparatus used for the fly ash cement solidification method according to any one of claims 1 to 3,
A fly ash container with a feeder;
A cement container with a feeder,
It is a horizontal biaxial type having a plurality of stirring blades connected to the fly ash container and the cement container, and automatically adjusts the rotation speed of the stirring shaft so that the mixture jumps up during the mixing and humidification process. A kneading machine;
A sprayer disposed above the kneader;
A fly ash cement solidifying apparatus comprising a discharge conveyor positioned on a discharge side of the kneader.

Images