JPS58115063A - Manufacture of ununiform lightweight aggregate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing irregularly shaped lightweight aggregate using fly ash as a raw material.

The exhaust gas generated from each wood boiler, heating furnace, incinerator, etc. contains a large amount of fine dust (fly ash). Such fly ash is collected using electrostatic precipitators, etc., but in order to make effective use of it, a method has been put into practical use by granulating and sintering it to make artificial lightweight aggregate. ing. In other words, fly ash originally contains some unburned carbonaceous material, but if necessary, combustible carbonaceous material (coal or coke fine powder) is added, kneaded with a binder (water), and then granulated into true spherical particles. The raw pellets are charged onto a moving grate and transported while being dried, preheated, ignited, sintered, heat-retained, and cooled to produce an artificial lightweight aggregate.

Figure 111 is an explanatory diagram illustrating the manufacturing procedure of such lightweight aggregate, in which fly ash (FA), carbon material for imparting self-combustibility, and water as a binder are put into a mixer 15 such as a bag mill. After kneading to form a flake-like mixture, the mixture is charged into a pan-type granulator No. 17 to form almost perfectly spherical raw pellets.

In this case, the amount of water blended is usually 16 to 16 to
It is set to a range of 231 days. The reason for this is to perform granulation efficiently and efficiently, and to increase the strength of the raw pellets to the crushing strength necessary to withstand transportation to the sintering machine (approximately 0.4 degrees or more of the pressure required to crush the pellets). Although the optimum water content varies slightly depending on the fly ash composition and particle size, by setting the amount of water within the above range, it is possible to obtain perfectly spherical raw pellets with appropriate crushing strength. There is.

On the other hand, the product (sintered) aggregate 2 is charged into the hopper 13 of the drying/sintering device, and is supplied as a bedding onto the movable grate 3 rotating in the direction of the arrow. The pellets I are charged to the top of the bedding layer via a hopper 16. The raw material layer thus formed is sequentially transferred from left to right in the drawing as the grate moves, passes through a drying/preheating furnace 4, an ignition furnace 5, and a sintering/retention furnace 6 to undergo sintering. It reaches the cooling zone 7 where it is sufficiently cooled and becomes a product aggregate. A plurality of wind boxes 8 are arranged along the conveyance direction at the bottom of the upper grate that conveys raw pellets 1, etc., and the lower narrow diameter part of the wind boxes 8 is connected to the return side (lower m1ll) fire. In order to avoid the grid, it is deflected in the direction penetrating the plane of the paper, and is opened and connected to the exhaust duct 9. The inside of the duct 9 is evacuated by a blower 10, and due to the suction airflow, a suction airflow is formed that passes through the raw material layer from top to bottom. Therefore, each furnace 4
, 5. If you connect a hot air introduction pipe to the top of 6,
High-temperature air is introduced into each furnace, descends between the raw material layers, and is discharged into the wind box 8.

That is, since the raw pellets have a spherical shape of 5 to 25 .phi., the ventilation resistance within the raw material layer is relatively low, and a downward airflow passing from the top to the bottom is easily formed. The disintegrating motion of the green pellets falling into the exhaust duct 9 falls onto the conveyor 12 through the chute 11 and is collected, and is generally returned and reused as a raw material for granulating the green pellets. In addition, 14 is a damper,
18 indicates a driving sprocket.

Since the product obtained by the method described above is obtained by directly firing the spherical raw pellets granulated using a pan-type granulator as described above, the final product can also be obtained as a spherical pellet. However, with spherical lightweight aggregates, ■ they easily roll on the belt during transportation and scatter around, ■ their angle of repose is small, so a large area is required to store them in piles, and the stock pile collapses during storage. ■People may step on aggregate scattered at the concrete construction towing yard and cause it to fall.
As such problems have been pointed out, there has recently been a demand for irregularly shaped aggregates that are not truly spherical.

The method for producing irregularly shaped lightweight aggregates is to crush or press the pellets vertically in the kiln to produce irregularly shaped raw pellets in a kiln, or to produce irregularly shaped pellets in advance using an extrusion molding machine or the like. Is there a method of producing pellets and sintering them?Is it possible to obtain deformed lightweight aggregate using a method that combines a pan-type granulator and a moving grate as shown in Figure 1? There's a problem. In other words, the pan-type granulator is originally a method suitable for obtaining spherical raw pellets, and by adjusting the inclination angle of the pan and the residence time of the granules on the pan, it is possible to make the granules irregularly shaped. Is it possible to achieve this, or is it impractical as it will seriously reduce productivity. Also, if the water content of the kneaded material, which is the raw material for granulation, is increased, it is thought that the spherical raw pellets will become flat and distorted due to their own weight.In reality, there is an upper limit to the water content that can be granulated. If the temperature is too high, granulation itself becomes difficult.

The present inventors focused on the above-mentioned circumstances and efficiently produced irregularly shaped lightweight aggregate using fly ash as a raw material using a granulation/calcination device that combines a pan-type granulator and a moving grate. We have been conducting research with the hope of establishing technology that will enable us to achieve this goal. The present invention was completed as a result of such research, and has a structure in which 16 to 23 layers of i
After adding 1% water and kneading, feed into a pan-type granulator, add 1 to 4 layers of water until granulation completes, form irregularly shaped raw pellets, and then dry.・There is a point in sintering.

The present invention is characterized by the process from kneading raw materials for granulation containing fly ash to forming green pellets. The mixture is kneaded with 16 to 23 centimeters of water and fed to a pan-type granulator.

The optimum water content varies slightly depending on the particle size and properties of the fly ash, but in order to achieve good kneading and granulation efficiency, it is necessary to set the water content within the above range. However, if the blended amount of water is less than 16%, kneading tends to be insufficient and the particle size of the granules becomes uneven, and as will be described later, even if a predetermined amount of water is added in the granulation process, irregularly shaped particles may occur. Can't get pellets. On the other hand, if it exceeds 23%, the moisture content of the mixed material becomes too high, making it difficult to granulate it using a pan-type granulator.

However, the above-mentioned preferred amount of water is the same as the conventional requirement for forming spherical pellets, and if this mixed material is granulated as it is according to the conventional method, only spherical raw pellets can be obtained. However, when this mixed material is fed to a pan-type granulator, 1 to 4% is added before or immediately after the start of granulation.
When granulation is performed by adding water, it is possible to obtain distorted raw pellets without inhibiting granulation.
By drying and sintering this according to a conventional method, a deformed lightweight aggregate can be obtained. In other words, the moisture content inside the raw pellets is about the same as that of the conventional example, so there is no risk of deterioration in granulation performance, but the water added during the granulation process may adhere to the surface of the raw pellets and make the surface soft. It is thought that this is to make it easier to make the granules into irregular shapes.

If the amount of water added is less than 1%, the above-mentioned effect of making the surface drinkable will not be effectively exerted, and the purpose of forming irregular shapes cannot be achieved, and if it exceeds 4%, the entire kneaded material will become a drink and granulation will not be possible. Sexuality is drastically reduced. In this case, it may be possible to add 1 to 4 liters of water to be added from the beginning of mixing the granulation raw materials, or if this is done, the water content of the mixing material will become too high and the granulation properties will deteriorate, or the excessive amount Since the moisture in the mold is uniformly dispersed throughout the cake, the deformation effect is not fully exerted.

That is, the greatest feature of the present invention is that 1 to 4 liters of excess moisture is added after mixing until granulation is completed, thereby increasing the moisture content of only the surface portion of the mixing material. , it can be made into irregular shapes without inhibiting granulation properties.

The irregularly shaped pellets shaped like a rice cake are made into a mobile character by the same method as shown in Figure 41; by charging the pellets onto a shell, drying, heating and baking, the irregularly shaped lightweight bones that maintain the irregular shape of the raw pellets are produced. Becomes wood. In the present invention, as mentioned above, the water content on the surface of the raw pellets is high, so if the pellets are left for a long time after granulation, there is a risk that the pellets will stick to each other and cause new blocking.・As long as a continuous sintering method is adopted, the above problems will not occur at all. The irregularly shaped lightweight aggregate obtained in this way has a shape as shown in Fig. 2 (a) to (a), for example, and is less likely to roll over than traditional perfectly spherical pellets, so it does not scatter during transportation or handling. Not only does this reduce the risk of workers falling over even if they step on it, but since the angle of repose is large and the stockpiles are less likely to collapse, the area of piles piled up on site is also reduced. Furthermore, since the surface area of the sides of the aggregate is larger than that of a perfectly spherical aggregate, the strength of the concrete material is improved, making it extremely practical.

The present invention is roughly constructed as described above, or is basically a simple construction in which 1 to 4% of water is added until granulation is completed using a pan-type granulator, and other steps are not changed at all. It has now become possible to produce irregularly shaped lightweight aggregates that meet market demands without causing problems or reducing productivity.

Next, an experimental example will be shown.

Practical Example 1 Fly ash and vertical material consisting of the following component composition and particle size distribution (5% in total, including unburned carbon in the fly ash)
) was mixed with 18% water.

[Fly ash composition]

810s: 50.6%, A/s Us: 24-0
'4, Fem0m:5. llCmO: 6-5%,
MgO: 1.6%, Nano: 2.2% KsO: 1.
4% [Fly ash particle size distribution] 149P wind or less: 95.4%, 44μm or less = 59% The obtained mixed material was put into a pan-type granulator, and the following was added as it was or with 2% water added. The raw pellets obtained by granulation were dried and sintered under the following conditions to obtain lightweight aggregates.

[Granulation conditions]

Diameter of granulator: 0.9m Inclination angle of granulator: 45 degrees Rotation speed of granulator: 25CI+/sec (clay speed) Retention filter of raw pellets: 23Q/Diameter of raw pellets: Half-uniform 12■ [Drying/sintering conditions] Amount of heat for preheating: 5000 kal/-・min x 2 minutes Amount of heat for ignition: 16000 kal/-・min x 2 minutes Amount of heat for heat retention: 20
00 kal/m's min x 6 min Cooling: Cold air IN
Table 1-ζ shows the physical properties and properties of the raw pellets and sintered products.

1st table pot 1: If it is Harutsune 2011 or higher, it can be used as a lightweight aggregate without any problem.

Qin S = horizontal length of product aggregate (in), vertical length (in)
A/B or more than 1.3 is used as irregularly shaped pellets, 1
Number of pieces included in 00 pieces As is clear from Table 1, most of the sintered products obtained in the comparative example (conventional method) were close to perfectly spherical, and the proportion of irregularly shaped pieces was 7 pieces. Only. On the other hand, more than 90% of the sintered products obtained in the examples were irregularly shaped, and only a few were close to perfectly spherical. In addition, there is almost no difference in crushing strength between the comparative example and the example for both raw pellets and sintered products, and the example shows a higher value.

Experimental Example 2 The following component composition and particle size distribution were used as the raw material fly ash, and the water mixing lid was 22 ng (additional moisture was 3%).
) A lightweight aggregate (sintered product) was obtained in the same manner as in Experimental Example 1.

[Fly ash composition]

5iσl: 45.41G, A l srs: 23.
1 '4, Feeσ1α or CaO: 8.0%, 'g
Oa 2.5% sNa sO* 0.5%,
KmO: 0.7 [Fly ash particle size distribution] 149 μm or less 299.8 rumored, 44 μm or less: 88.5
Table 2 shows the physical properties and properties of the raw pellets and sintered products.

2nd Table Qin 1. Mine 3: As is clear from Table 2, the proportion of irregularly shaped particles obtained by the conventional method (comparative example) is less than 5% of the total, but the proportion of irregularly shaped particles obtained by the present invention (comparative example) is less than 5% of the total.
According to the embodiment, 91 or more of the total number of irregularly shaped parts can be made.

[Brief explanation of drawings]

FIG. 1 is a schematic process diagram showing a method of granulating and sintering fly ash, and FIGS. 2(a) to 2(a) are schematic diagrams illustrating a deformed lightweight aggregate obtained by the present invention. 1... Raw pellets, 2... Product aggregate, 3... Moving grate, 4... Drying/preheating furnace, 5... Ignition furnace, 6
... Sintering/heat retention furnace, 7... Cooling zone, Death... Wind box, 15... Mixer, 17... Pan type granulator.

Claims (1)

[Claims] (11) In order to produce lightweight aggregate by adding water to the powder containing ply ash, mixing it, granulating it with a pan fIIi!1 granulator, and then drying and sintering, the granulating raw material is
Irregular shapes characterized by adding 23 kg of water and kneading, adding 1 to 4 kg of water until granulation is completed to form irregular shaped raw pellets, and then drying and sintering. Manufacturing method of lightweight aggregate.