JP2001261390A - Method of producing artificial light-weight aggregate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a granulation method of producing artificial light-weight aggregate by a high-pressure steam curing using a simple facility, enabling easy control of the specific gravity and giving an extremely soft granule. SOLUTION: The objective method comprises the 1st step to form a slurry by kneading a siliceous raw material, a calcareous raw material and water, the 2nd step to cure the slurry obtained by the 1st step by casting the slurry in a casting extrusion vessel, the 3rd step to granulate the plastic cake obtained by the 2nd step by vertically extruding the cake through a die by its own weight or with a piston while applying vibration to the die and the curing step. The slurry may be incorporated with aluminum metal powder. Preferably, the frequency of the vibration to be applied to the die is 50-300 Hz, the amplitude is 0.2-2 mm and the viscosity of the plastic cake is 30-1,500 Pa.s. The method is further provided with the 4th step to drop the granule on dried powder bed on a conveyor to scatter the dried powder on the surface of the granule and the 5th step to adjust the granule size with a crusher and sizing the granule with a rolling granulator.

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 an artificial lightweight aggregate, and more particularly, to an artificial lightweight aggregate for construction and civil engineering obtained by granulating from industrial waste such as coal ash, sewage sludge and construction sludge. About.

[0002]

2. Description of the Related Art Industrial waste generated in large quantities such as coal ash, sewage sludge and construction sludge can be used as an artificial lightweight aggregate as an effective utilization technology. Suitable in terms of.

[0003] However, compared with the crushed stone currently supplied to most of the aggregate, the artificial lightweight aggregate has many problems in terms of cost. The present inventors have proposed a method for producing artificial lightweight aggregates other than a general method for producing artificial lightweight aggregates by high-temperature sintering. Aggregate manufacturing methods have been proposed.

[0004] In the method of producing artificial lightweight aggregate by firing,
As a method of granulating the aggregate, a granulation method by tumbling granulation or extrusion is generally used, and the specific gravity of the aggregate can be controlled by selecting a foaming agent or a firing method. However, in the case of artificial lightweight aggregates cured by high temperature steam, it is difficult to control the specific gravity of the aggregates by these methods, and it is particularly difficult to reduce the specific gravity. As a method for reducing the specific gravity of the aggregate, in a conventional technique, a method of casting a slurry into a mold and cutting the slurry in a semi-cured state is general. However, in these methods, a large number of molds and cutting devices are required for practical production, so that the equipment and investment are excessive, and the operating costs are increased, resulting in an increase in manufacturing costs. Therefore, it was necessary to develop a simple and inexpensive granulation method.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to produce an artificial lightweight aggregate by high-pressure steam curing, in which specific gravity can be easily controlled, granulation can be made extremely soft, and simple equipment can be used. This is a method for producing an artificial lightweight aggregate using a granulation method.

Another object of the present invention is to provide a method for obtaining an artificial aggregate having a bulk specific gravity of 0.5 to 1.5 and a crushing strength of 5 to 70 kgf at low cost.

[0007]

The first aspect of the method for producing an artificial lightweight aggregate according to the present invention comprises a first step of kneading a siliceous raw material, a calcareous raw material and water to form a slurry, and a first step. A second step in which the slurry obtained in step 2 is cast into a casting extrusion bath and hardened, and a third step in which the plastic cake obtained in the second step is extruded vertically by its own weight and granulated while applying vibration to the die, It consists of a curing process.

A second aspect of the method for producing an artificial lightweight aggregate according to the present invention comprises a first step of kneading a siliceous raw material, a calcareous raw material and water to form a slurry, and adding metallic aluminum powder to the slurry; The slurry obtained in one step is cast into a casting extrusion tank, foamed, expanded, and cured to form a second slurry.
A third step in which the plastic cake obtained in the second step is extruded vertically by its own weight while applying vibration to the die, and granulated.
And a curing process.

In the first and second aspects, the vibration applied to the die has a frequency of 50 to 300 Hz and an amplitude of 0.2 to 2 Hz.
mm. Further, the viscosity of the plastic cake,
The pressure is preferably 30 to 1500 Pa · s.

A third aspect of the method for producing an artificial lightweight aggregate according to the present invention comprises a first step of kneading a siliceous raw material, a calcareous raw material, and water to form a slurry, and a slurry obtained in the first step. A second step of casting and hardening by casting in a casting extrusion tank, and a third step of extruding the plastic cake obtained in the second step vertically from a die by a piston method and granulating the plastic cake,
It consists of a curing process.

A fourth aspect of the method for producing an artificial lightweight aggregate according to the present invention comprises a first step of kneading a siliceous raw material, a calcareous raw material and water to form a slurry, and adding metallic aluminum powder to the slurry; A second step in which the slurry obtained in the first step is cast into a casting extrusion tank, foaming, expanding and curing, and a third step in which the plastic cake obtained in the second step is extruded from a die in a vertical direction by a piston method and granulated. And a curing process.

Here, coal ash, sewage sludge or industrial sludge of construction sludge can be used as the siliceous raw material. In addition, although quicklime, slaked lime and cement are used as the calcareous raw material, calcareous industrial waste may be used.

The viscosity of the plastic cake is from 30 to 150.
The pressure is preferably 0 Pa · s.

In any one of the above-mentioned embodiments, the fourth step of dropping the granules obtained in the third step onto a dry powder bed on a conveyor and spraying the dry powder on the surfaces of the granules is performed. It is good to have. The dry powder is desirably coal ash or cement powder. Further, it is preferable to have a fifth step of adjusting the particle size by a crusher and adjusting the particle size by a rolling granulator.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing an artificial lightweight aggregate according to the present invention comprises a first step of kneading, a second step of casting, a third step of granulation, and a curing step. Furthermore, before the curing step, the fourth step of applying powder and the fifth step of sizing are performed.
A step may be provided before the curing step.

First, the first step of kneading will be described.

A siliceous raw material, a calcareous raw material, and water are kneaded to form a slurry. If necessary, gypsum may be added.

It is preferable to add a foaming agent such as aluminum metal powder to the slurry, cast the slurry into a casting and extrusion tank, and foam and expand to a desired specific gravity. Alternatively, the slurry is directly cast into a casting extrusion tank,
Bubbles created in advance may be mixed to reduce the weight so as to have a desired specific gravity.

As the siliceous raw material, the coal ash used in the present invention is not particularly limited. For example, JIS 620
All coal ash can be used, including fly ash, coarse powder, clinker ash, etc., that meet 1. Further, sewage sludge, construction sludge and the like can also be used.

As the calcareous raw material, calcium oxide and / or calcium hydroxide or cement is used in order to develop strength by a pozzolanic reaction with silica or alumina which is a main component in the coal ash of the siliceous raw material. Calcareous industrial waste may be used.

[0021] The cement used in the present invention is not particularly limited. For example, ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, moderately heated Portland cement, sulfate-resistant Portland cement, white salt specified in JIS standards Examples include cement, ultra-rapid hardening cement, alumina cement, silica cement, blast furnace cement, fly ash cement and the like.

The amount of calcium in terms of oxide in the formation of aggregate is 1 to 50% by weight, preferably 1 to 50% by weight, from the viewpoint of improving the strength of the artificial lightweight aggregate and the utilization rate of coal ash.
To 40% by weight.

As described above, water is added to a mixture of coal ash and the like, calcium oxide and / or calcium hydroxide, cement and the like for wet kneading, but the kneading method used is not particularly limited. A known kneading device can be used.

The amount of water used for kneading is 40 to 80% by weight based on the total solid mass. If it is less than 40% by weight, the slurry has a high viscosity and cannot be discharged from the mixer in a short time. On the other hand, if the content is more than 80% by weight, it takes a long time to cure the raw cake and the strength of the aggregate decreases, so that it is not practical. Further, in order to promote curing, it is preferable to stir with warm water of about 40 to 90 ° C.

Next, the second step of performing casting will be described.

The casting extrusion tank needs to be large enough to store the cast slurry for about 1 to 3 hours. Also,
When the slurry is hardened, the calcareous raw material hydrates or reacts with the siliceous raw material to form calcium silicate hydrate, which causes an exothermic reaction. Differences are likely to occur. Therefore, it is preferable to keep or warm the slurry container so that the inside and outside temperatures become uniform.

In a state where the slurry obtained in the second step has plasticity while retaining the internal bubbles and is hardened to such an extent that it can be easily extruded from a die or a metal wire mesh, the slurry has a viscosity of 30 to 1500 Pa · s. At that point, it is extruded through a die to form a plastic cake.

Next, the third step of performing granulation will be described.

A die, or a die and a casting and extrusion tank, are subjected to a frequency of 50 to 300 Hz and an amplitude of 0.2 to 2 mm.
It is preferable to extrude the plastic cake by applying the vibration described above.
In the present invention, the viscosity of the slurry at the time of extrusion is defined as the viscosity of the plastic cake.

The plastic cake has a strong thixotropy and is formed into a slurry when vibration is applied. Further, the surface of the slurry in contact with the holes of the die is fluidized and becomes extremely low in viscosity, and is extruded from the die by its own weight. Since the hardened slurry itself easily absorbs vibration, the inside maintains a high viscosity state. Therefore, the air bubbles are discharged from the die while maintaining the air bubbles.

When the frequency applied to the die or the die and the casting and extrusion tank is 50 Hz or less, the effect of lowering the slurry is insufficient depending on the viscosity of the slurry, and the slurry cannot be discharged by its own weight. When the frequency is 300 Hz or more, the vibration in the hardened slurry is greatly attenuated, the formation of a low-viscosity layer necessary for extrusion is insufficient, and the energy efficiency is poor.

As for the amplitude, usually, the average diameter of the extrusion is about 10 mm. If the amplitude is less than 0.2 m, the formation of the low-viscosity layer is not sufficient, and if the amplitude is 2 mm or more, the low-viscosity layer is excessively formed. However, the specific gravity of the resulting artificial lightweight aggregate tends to increase.

The vibration affects the discharge of the plastic cake from the die in relation to the viscosity, but does not affect the physical properties of the produced artificial aggregate, that is, the bulk specific gravity or the crushing strength.

Regarding the viscosity of the plastic cake, 30 Pa
At less than s, the plastic cake extruded by pressurization is defoamed without maintaining its shape, and the specific gravity cannot be reduced. Further, when the viscosity of the plastic cake is 1500 Pa · s or more, the viscosity of the plastic cake is not sufficiently reduced by vibrating the surface of the plastic cake, and the plastic cake cannot be extruded by its own weight.

The die opening is 10 mm square, and the extruded plastic cake is dropped by its own weight during extrusion, or is intermittently applied with a vibration applied to the die, or the die and the casting and extrusion tank. Cut to size.

As a different embodiment of the third step, the following step may be performed.

The plastic cake obtained in the second step is extruded with a piston in a state where the plastic cake has plasticity while retaining the internal bubbles and is hardened to such an extent that it can be easily extruded from a die or a metal wire mesh. The degree of hardening of the slurry suitable for extrusion molding is a degree of hardening that allows the plastic cake to be easily extruded from a die or a metal wire mesh while retaining plastic bubbles, and has a viscosity of 30 to 1500 Pa · s. is there.

Regarding the viscosity of the plastic cake, 30 Pa
At below s, the slurry extruded by pressurization is defoamed without maintaining its shape, and the specific gravity cannot be reduced. Further, when the viscosity of the plastic cake is 1500 Pa · s or more,
Extrusion resistance becomes excessive, the dies and metal wire mesh cannot withstand the pressure, and the hardened slurry itself is subjected to consolidation, and the specific gravity cannot be reduced. Basically, extrusion by only vibration is preferred, but the presence or absence of piston extrusion depends on whether or not the slurry or cake continuously breaks in the casting and extrusion tank. When the slurry or cake is clogged in the casting / extruding tank only by vibration, piston extrusion is performed, or piston extrusion is used for vibration.

A method of continuously extruding with a piston will be described with reference to FIGS.

The slurry is cast into the casting extrusion tank at regular intervals in a batch system. For each casting, press plate 1
3 is inserted into the drive shaft 11.

At several places (five places in the illustrated example) of the drive shaft 11, three press plate holding blades 11a are attached at equal intervals at 120 ° intervals. The push plate 13 can be divided into two parts, or the upper end of the drive shaft 11 can be separated from a drive device (not shown). Push plate 1
3 includes a drive shaft 11 at the center and a push plate holding blade 1
There is provided a hole 13b for passage with 1a. The pressing plate 13 is made of a material having a specific gravity lower than that of the slurry, and is made to float on the surface of the slurry after the casting of the slurry.

When the push plate 13 is inserted into the drive shaft 11, the portion of the hole 13b through which the push plate holding blade 11a passes and the push blade 11a are set so as to be shifted by 60 °. At the end of the push plate 13 and the inner wall of the casting extrusion tank,
It is preferable that a cut 13a and a vertical guide (not shown) are provided at one or two places, respectively, so that the extrusion plate 13 does not rotate in the horizontal direction.

The slurry is sequentially pressed and moved by the push plate 13 while being hardened toward the lower part of the casting extrusion tank, but the volume of the slurry fluctuates due to continuation of foaming or the like from 30 minutes to 1 hour after the casting. Therefore, it is preferable to provide a gap between the extrusion plate 13 and the casting extrusion bath so that the slurry can move to the upper portion of the push plate 13 when the slurry volume increases. When the pressing plate 13 immediately above the extrusion die 14 reaches the extrusion die 14,
The drive shaft 11 is rotated by 60 ° so that the position of the push plate holding blade 11a matches the position of the hole 13b where the push plate holding blade passes, and is pulled up by one interval of the push plate 13. Then, the drive shaft 11 is again rotated by 60 °, and the movement and the extrusion of the slurry and the plastic cake are repeated while pressing the push plate 13 one step higher. Drive shaft 1
Before the extrusion is resumed after the rise of the extrusion die 1, an openable lid (not shown) provided on the upper portion of the extrusion die 14 is opened at the side of the casting extrusion tank, and the push plate reaching the extrusion die 14 is opened. 13 is pulled out in the horizontal direction, the lid is closed, and the extrusion is started again.

The opening of the die is 10 mm square, and the extruded plastic cake is dropped by its own weight during the extrusion, or cut into a predetermined size by applying vibration to the die.

With the above, different aspects of the third step are completed.

Next, the fourth step of applying powder will be described.

A silicate material such as coal ash or a dry powder obtained by mixing and pulverizing a calcareous material such as quick lime, slaked lime or cement with the siliceous material is sprinkled on the surface of the extruded grains.
Prevents grains from adhering to each other. Specifically, a moving conveyor belt is placed under a die or an extrusion die, and the dried powder is dropped on the belt, and laid with a layer thickness of about 3 to 3 times the particle size of the particles. Then, the dropped particles are buried in the powder layer. If the thickness of the powder layer is less than the diameter of the pellet, the dried powder cannot be sufficiently sprinkled on the pellets, and the pellets may adhere to each other. In addition to burying in the powder layer of dry powder, it is also possible to drop particles on a thinly laid dry powder, sprinkle the dry powder on it, or spray the dry powder dispersed in the air stream on the particles Powdering is possible.

The dry powder may have the same raw material composition as that of the slurry. However, it is also possible to use a composition or a raw material having a higher strength than the particles obtained from the slurry by high-pressure steam curing described later.

Next, the fifth step of sizing will be described.

The mixture of the dried powder and the particles coated with the dried powder is separated from the dried powder and the particles by a vibrating sieve. The separated powder is used again for preventing adhesion of the extruded granules or used as a raw material for preparing a slurry. If the particles thus obtained are larger than the required size, they are ground to a predetermined size. If necessary, these particles are put into a granulator such as a pan or a drum and rolled to make corners of the particles, and at the same time, to densify the bulky dry powder attached to the surface and improve the strength. Contribute. In order to further increase the strength of the surface, a cement powder can be simultaneously coated, or a material capable of providing a necessary function can be coated.

The specific gravity is controlled by using metallic aluminum powder. When the specific gravity is 1.3 to 1.5, the specific gravity is controlled by the water solids ratio. At 0.02% by weight and 0.8 at specific gravity, about 0.04% by weight is added. At 0.5 at specific gravity, about 0.06% by weight is added.

Finally, the curing step will be described.

As curing methods, wet curing, steam curing at normal pressure and steam curing at high pressure are known. In the present invention, it is preferable to use high pressure steam curing or normal pressure curing in combination with high pressure steam curing. In particular, the normal-pressure steam curing alone requires a long curing time before the strength is developed, resulting in poor productivity. The conditions of the high-pressure steam curing performed in the autoclave are at 110 to 250 ° C. for 1 hour or more, preferably 3 to 250 ° C. from the viewpoint of productivity and aggregate strength.
More than an hour.

As described above, the aggregate specific gravity after curing is 0.5
It is possible to arbitrarily control up to 1.5, and the above-mentioned problem can be solved.

(Examples) Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples.

However, the present invention is not limited to the following examples.

(Example 1) Coal ash 80% by weight, calcium oxide 5% by weight, ordinary Portland cement 15% by weight
50% by weight of water at a temperature of 60 ° C. was added to the total amount of the aggregate-mixed raw material consisting of
Approximately 10 L was cast into a casting extrusion tank provided with a 5 mm × 500 mm height, 10 mm square spread, and 25 mm thick extrusion section in the extrusion direction.

The main component of coal ash is SiO ₂ : 59.3.
%, Al ₂ O ₃ : 31.6%, Fe ₂ O ₃ : 2.9%, Ca
O: 0.9%, MgO: 0.5%, Na ₂ O: 0.2
%, K ₂ O: 0.3%.

The lower part of the extruded portion is covered with a cover so that the slurry is not discharged at the casting location. About 1 after casting
After the time, when the viscosity of the cake became 30 Pa · s, the lid at the bottom of the die was removed, and the frequency of the die was 200 Hz and the amplitude was 1 m.
m and a vibration was applied. The cake viscosity was measured with a cylindrical rotary viscometer.

A premixed dry powder having the same composition as the slurry raw material is laid on a stainless steel vat to a thickness of about 20 mm, and the extruded and cut particles are dropped on the powder layer while moving the stainless vat. Granules and powder were separated by a 5 mm sieve.

While rolling the granules with a pan pelletizer, the powder on the surface was thickened to finish the grain surface smoothly.
The particles were pre-cured for 3 hours in a high-temperature and high-humidity atmosphere at 50 ° C. and a relative humidity of 95%.
The high-pressure steam curing was performed for 8 hours.

As an evaluation of the obtained artificial lightweight aggregate, the bulk specific gravity and the crushing strength (uniaxial compression breaking load) were measured. The crushing strength was measured by a crushing tester with a diameter of about 10 mm.
The artificial lightweight aggregate was measured at 15 points, and the strength at a diameter of 10 mm was determined from a regression equation of the strength to the particle size. The specific gravity was measured according to JISA1135. Table 1 shows the evaluation results.

(Example 2) In Example 2, a method similar to that of Example 1 was adopted except that the curing time in the casting and extrusion tank of Example 1 was set to about 2 hours and the viscosity of the plastic cake was set to 550 Pa · s. Made an artificial lightweight aggregate.

(Example 3) In Example 3, a method similar to that of Example 1 was adopted except that the curing time in the casting and extrusion tank of Example 1 was set to about 3 hours, and the viscosity of the plastic cake was set to 1500 Pa · s. Made an artificial lightweight aggregate.

In each case, the same evaluation and measurement were performed. Table 1 shows the evaluation results.

As shown in Table 1, in Examples 1 to 3, artificial lightweight aggregates having a bulk specific gravity of 1.22 to 1.36 and a crushing strength of 49 to 61 kgf were obtained.

(Example 4) In Example 4, water was added to the raw material powder of Example 2 to form a slurry using a mixer.
Metal aluminum powder 0.02 to the total amount of slurry
% By weight, and after mixing and stirring, an artificial lightweight aggregate was prepared in the same manner as in Example 2, except that the mixture was cast into a casting extrusion tank.

Example 5 In Example 5, water was added to the raw material powder of Example 2 to form a slurry using a mixer.
Metal aluminum powder 0.04 to the total amount of slurry
% By weight, and after mixing and stirring, an artificial lightweight aggregate was prepared in the same manner as in Example 2, except that the mixture was cast into a casting extrusion tank.

Example 6 In Example 6, water was added to the raw material powder of Example 2 to form a slurry using a mixer.
Metal aluminum powder 0.06 to the total amount of slurry
% By weight, and after mixing and stirring, an artificial lightweight aggregate was prepared in the same manner as in Example 2, except that the mixture was cast into a casting extrusion tank.

In each case, the same evaluation and measurement were performed. Table 1 shows the evaluation results.

As shown in Table 1, Examples 4 to 6 have a bulk specific gravity of about 0.52 to 0.91 and a crush strength of about 7 to 22 kg.
The artificial lightweight aggregate of f was obtained.

(Example 7) In Example 7, an artificial lightweight aggregate was prepared in the same manner as in Example 4 except that the frequency applied to the die of Example 4 was set to 50 Hz.

(Embodiment 8) In the eighth embodiment, except that the frequency applied to the die of the fourth embodiment is set to 300 Hz.
An artificial lightweight aggregate was prepared in the same manner as described above.

In each case, the same evaluation and measurement were performed. Table 1 shows the evaluation results.

As shown in Table 1, Examples 7 and 8 had a bulk specific gravity of about 0.87 to 1.02 and a crush strength of about 20 to 32 k.
gf artificial lightweight aggregate was obtained.

Example 9 In Example 9, an artificial lightweight aggregate was prepared in the same manner as in Example 4 except that the amplitude of the vibration applied to the die of Example 4 was 0.2 mm.

(Embodiment 10) In Embodiment 10, Embodiment 4
An artificial lightweight aggregate was prepared in the same manner as in Example 4 except that the amplitude of the vibration applied to the die was 2 mm.

In each case, the same evaluation and measurement were performed. Table 1 shows the evaluation results.

As shown in Table 1, Examples 9 and 10 had a bulk specific gravity of about 0.86 to 0.98 and a crushing strength of about 18 to 25.
An artificial lightweight aggregate of kgf was obtained.

Comparative Example 1 In Comparative Example 1, casting and extrusion were performed in the same manner as in Example 1 except that the curing time in the casting and extrusion tank was set to about 30 minutes and the viscosity of the plastic cake was set to 20 Pa · s. Although granulation was attempted, the granules were not formed into a shape of about 10 mm when dropped into the dry powder, and granulation was impossible.

Comparative Example 2 In Comparative Example 2, the casting was carried out in the same manner as in Example 4 except that the curing time in the casting extrusion bath was set to about 3.5 hours and the viscosity of the plastic cake was set to 2000 Pa · s. Although extrusion granulation was attempted, the plastic cake was compacted due to the progress of curing, but could not be extruded.

[0082]

[Table 1]

(Example 11) 50% by weight of water at a temperature of 60 ° C was added to the total amount of the aggregate-mixed raw material composed of 80% by weight of coal ash, 5% by weight of calcium oxide, and 15% by weight of ordinary Portland cement. After mixing with a mixer,
Approximately 10 L was cast into a casting extrusion tank provided with an extruding section having a size of 05 mm × a height of 500 mm, a spread of 10 mm □, and a thickness of 25 mm in the extrusion direction.

The main component of coal ash is SiO ₂ : 59.3.
%, Al ₂ O ₃ : 31.6%, Fe ₂ O ₃ : 2.9%, Ca
O: 0.9%, MgO: 0.5%, Na ₂ O: 0.2
%, K ₂ O: 0.3%.

The lower part of the extruded portion is covered with a lid so that the slurry is not discharged at the casting location. About 1 after casting
After a time, when the viscosity of the plastic cake became 30 Pa · s, a push plate was put above the slurry, and the slurry was extruded by pressing from above. The viscosity was measured with a cylindrical rotary viscometer.

A premixed dry powder having the same composition as that of the slurry raw material is spread on a stainless steel vat to a thickness of about 20 mm, and the extruded and cut particles are dropped on the powder layer while moving the stainless steel vat. Granules and powder were separated by a 5 mm sieve.

While the particles were rolled with a pan pelletizer, the powder on the surface was compacted to smooth the surface of the particles.
The particles were pre-cured for 3 hours in a high-temperature and high-humidity atmosphere at 50 ° C. and a relative humidity of 95%.
The high-pressure steam curing was performed for 8 hours.

As the evaluation of the obtained artificial lightweight aggregate, the bulk specific gravity and the crushing strength (uniaxial compression breaking load) were measured. The crushing strength was measured by a crushing tester with a diameter of about 10 mm.
The artificial lightweight aggregate was measured at 15 points, and the strength at a diameter of 10 mm was determined from a regression equation of the strength to the particle size. The specific gravity was measured according to JISA1135. Table 2 shows the evaluation results.

(Embodiment 12) In Embodiment 12, Embodiment 1
Example 1 except that the curing time in the casting extrusion bath was about 2 hours and the viscosity of the plastic cake was 550 Pa · s.
An artificial lightweight aggregate was prepared in the same manner as in Example 1.

(Embodiment 13) In Embodiment 13, Embodiment 1
An artificial lightweight aggregate was prepared in the same manner as in Example 11 except that the curing time in the casting extrusion bath was set to about 3 hours and the cake viscosity was set to 1500 Pa · s.

In each case, the same evaluation and measurement were performed. Table 2 shows the evaluation results.

As shown in Table 2, in Examples 11 to 13, the bulk specific gravity was 1.27 to 1.48 and the crushing strength was 52 to 63 k.
gf artificial lightweight aggregate was obtained.

(Embodiment 14) In the fourteenth embodiment, the first embodiment
After water was added to the raw material powder of No. 2 to form a slurry with a mixer, the metal aluminum powder 0.0
An artificial lightweight aggregate was prepared in the same manner as in Example 12, except that 2% by weight was added, and the mixture was further mixed and stirred and then cast.

(Embodiment 15) In Embodiment 15, the first embodiment
After water was added to the raw material powder of No. 2 to form a slurry with a mixer, the metal aluminum powder 0.0
An artificial lightweight aggregate was prepared in the same manner as in Example 12, except that 4% by weight was added, and the mixture was further mixed and stirred and then cast.

(Embodiment 16) In Embodiment 15, Embodiment 1
After water was added to the raw material powder of No. 2 to form a slurry with a mixer, the metal aluminum powder 0.0
An artificial lightweight aggregate was prepared in the same manner as in Example 12, except that 6% by weight was added, and the mixture was further stirred and cast and then cast.

In each case, the same evaluation and measurement were performed. Table 2 shows the evaluation results.

As shown in Table 2, Examples 14 to 16
Bulk specific gravity of about 0.54 to 1.01, crush strength of about 8 to 36
kgf of aggregate was obtained.

Comparative Example 3 In Comparative Example 3, casting and extrusion were performed in the same manner as in Example 11, except that the curing time in the casting and extrusion tank was set to about 30 minutes and the viscosity of the plastic cake was set to 20 Pa · s. Although granulation was attempted, the granules were not formed into a shape of about 10 mm when dropped during drying, and granulation was impossible.

Comparative Example 4 In Comparative Example 4, the casting was performed in the same manner as in Example 14 except that the curing time in the casting extrusion bath was set to about 3.5 hours and the viscosity of the plastic cake was set to 2000 Pa · s. Although extrusion granulation was attempted, the plastic cake was compacted due to the progress of curing, but could not be extruded.

[0100]

[Table 2]

[0101]

According to the present invention, the equipment and work for taking out and cutting a fresh cake from a large number of cast molds can be greatly simplified in the conventional cellular concrete production technology. As a result, non-burning type, specific gravity adjustment is easy, and extremely soft artificial light weight is obtained from industrial waste such as coal ash, sewage sludge or construction sludge generated from coal-fired power plants and coal-fired boilers. Aggregate can be produced effectively at low cost. Accordingly, the ability to supply inexpensive, high-quality artificial lightweight aggregates to the market greatly contributes to the civil engineering and construction industries.

[0102] Further, since industrial waste can be recycled into civil engineering and building materials without reclaiming and treating it, it greatly contributes to environmental conservation and energy saving.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of a casting extrusion bath used in the production method of the present invention.

FIG. 2 is a side view of a drive shaft.

FIG. 3 is a plan view of a push plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Drive shaft 11a Push plate holding blade 13 Push plate 13a Cut 13b Hole 14 Extrusion die

Claims (8)

[Claims] 1. A first step of kneading a siliceous raw material, a calcareous raw material, and water to form a slurry, and a second step of casting the slurry obtained in the first step into a casting extrusion tank and hardening into a plastic cake. And extruding the plastic cake obtained in the second step from the die in the vertical direction by its own weight to granulate the third step.
A method for producing an artificial lightweight aggregate comprising a process and a curing process. 2. A first step in which a siliceous raw material, a calcareous raw material and water are kneaded to form a slurry, and a metal aluminum powder is added to the slurry. Production of artificial lightweight aggregate comprising a second step of expanding and hardening into a plastic cake, a third step of vertically extruding the plastic cake obtained from the die by its own weight from a die and granulating, and a curing step Method. 3. A first step in which a siliceous raw material, a calcareous raw material, and water are kneaded to form a slurry, and a second step in which the slurry obtained in the first step is cast into a casting extrusion tank and hardened into a plastic cake. A method for producing an artificial lightweight aggregate comprising a third step of extruding the plastic cake obtained in the second step from a die in a vertical direction by a piston method to granulate, and a curing step. 4. A first step in which a siliceous raw material, a calcareous raw material, and water are kneaded to form a slurry, and a metal aluminum powder is added to the slurry, and the slurry obtained in the first step is cast into a casting extrusion tank, and foamed. A second step of expanding and hardening into a plastic cake, a third step of extruding the plastic cake obtained in the second step from a die in a vertical direction by a piston method and granulating, and a curing step; Production method. 5. The method for producing an artificial lightweight aggregate according to claim 1, wherein a vibration is applied to the die in the third step. 6. The plastic cake has a viscosity of 30-15.
The method for producing an artificial lightweight aggregate according to any one of claims 1 to 5, wherein the pressure is 00 Pa · s. 7. A fourth step of dropping the granules obtained in the third step onto a dry powder bed on a conveyor and spraying dry powder on the surface of the granules before the curing step. The method for producing an artificial lightweight aggregate according to any one of claims 1 to 6, characterized in that: 8. The method for producing an artificial lightweight aggregate according to claim 7, wherein a fifth step of adjusting the particle size by a crusher and sizing by a tumbling granulator is provided before the curing step.