JPH10231152A - Artificial lightweight aggregate and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low-specific gravity, non-water absorbing and high-strength artificial lightweight aggregate. SOLUTION: This artificial lightweight aggregate is obtained by forming only one cavity 2a disappearing by baking in nearly the center of a sintered compact 1 made of an industrial waste as a main raw material, forming a sintered compact shell 3 covering the cavity 2a disappearing by baking and further forming a nonporous covering layer 4 covering the whole outer surface of the sintered compact shell 3. The aggregate has a specific gravity within the range of 0.8-1.6, a water absorption coefficient within the range of <=1.0%, and a collapse strength within the range of 1-1.6kN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial lightweight aggregate and a method for producing the same, and more particularly, to a low specific gravity and low water absorption using industrial waste such as water sludge, sewage sludge and construction sludge as a main raw material. TECHNICAL FIELD The present invention relates to an artificial lightweight aggregate having high strength and high strength, and a method for producing an artificial lightweight aggregate capable of individually adjusting the characteristics thereof.

[0002]

2. Description of the Related Art Conventionally, a technique for reusing so-called industrial waste has been developed from the viewpoint of a rise in disposal costs and a decrease in landfill sites. In the field of aggregates for cement according to the present invention, various technologies relating to lightweight aggregates using industrial waste as a main raw material have been proposed.

[0003] For example, JP-A-51-105327, foundry industry wastes, slag, waste oil sludge, sugar refining sludge, sugar sludge, and water purification plant sludge, further from quarry waste mud lightweight aggregate main component SiO ₂ A technique is disclosed in which Al ₂ O ₃ , a flux and a gas-generating substance are contained, a raw material blending is performed so as to have a lightweight aggregate forming ability, and this is granulated and fired to obtain an artificial lightweight aggregate. (Hereinafter referred to as Prior Example 1).

[0004] In the technique of the prior art 1, during firing, SiO ₂ , Al ₂ O _3, etc. contained in the foundry industrial waste itself act as an aggregate main component and a vitrification component on the aggregate surface.
Also CaO contained in foundry industry waste itself, MgO, Fe ₂ O
_By acting as a gas foaming component, _{3 and the} like reduce the specific gravity by foaming the aggregate as a product and reduce the water absorption by vitrifying the surface of the aggregate. Also, in the case of using the slag, the waste oil sludge, the refined sludge, the sugar sludge, and the water purification plant sludge, the content of the raw material itself such as SiO ₂ and Al ₂ O _{3 which} are the main components of the aggregate is small. It also discloses that it is necessary to mix the raw materials by combining casting industrial waste and the like to supplement this.

JP-A-51-105329 discloses that the composition of an inorganic substance is about 50 to 74% by weight of SiO _2, about 8 to 25% by weight of Al ₂ O ₃ , and about 1.5 to 18% by weight of an alkali oxide. %, In the manufacturing method of artificial lightweight aggregate in which the casting industrial waste which is the remaining impurities is blended and granulated and fired, the amount of Fe ₂ O ₃ in the waste, especially in the waste, should not exceed about 20% by weight. Accordingly, a technique for suppressing abnormal foaming in Fe ₂ O ₃ has been disclosed.

The prior arts 1 and 2 are techniques for vitrifying the aggregate surface by vitrifying components contained in the industrial waste itself, which is the main raw material, or by mixing the vitrifying component with the main raw material. Japanese Unexamined Patent Publication (Kokai) No. 2-283678 discloses a method for preventing the fusion during firing and the strength when used for concrete by attaching a vitrified component to the surface of the granulated material during granulation. There is proposed a technology for increasing the number (hereinafter, Prior Art 3
).

On the other hand, these prior art examples 1 to 3 aim at lowering the specific gravity by foaming the aggregate only by the gas generating components contained in the industrial waste itself. There is a technique disclosed in Japanese Patent Application Laid-Open No. 294692 (hereinafter referred to as Prior Example 4). That is, prior example 4
In this method, granulated paper or a mixture of ground paper and construction sludge is used as a granulation core, and the surface of the granulation core is coated with construction sludge or a mixture of construction sludge and ground paper to form a two-layer granulated material. A method for producing an aggregate for firing granules is disclosed. Regarding the structure of the aggregate obtained by the method, the publication discloses, in the same gazette, a large cavity due to the disappearance of the burning of the crushed paper in the granulation nucleus, and an innumerable number due to the reduction in foaming. Are formed and the surface layer is vitrified.
It is explained.

[0008]

However, prior art examples 1 to 4
According to the technique described above, it was extremely difficult to individually adjust properties such as specific gravity, water absorption and strength. Therefore, aggregates excellent in all of these characteristics could not be obtained by the techniques of Prior Examples 1 to 4.

In other words, the techniques of Prior Examples 1 to 3 are to produce porous aggregates as products by generating gas from a gas generating substance contained in industrial waste itself during baking and foaming the inside of granules. To reduce the specific gravity. Therefore, according to such a conventional method, it is possible to reduce the specific gravity by, for example, increasing the degree of porosity, but excessive porosity increases the water absorption or decreases the strength. It was difficult to adjust various characteristics such as specific gravity and the like individually.

Further, in order to increase the porosity in the techniques of the prior art examples 1 to 3, it is necessary to include a gas generating substance in the raw material,
It is necessary that the generated glass phase has such a high viscosity that the generated gas can be retained, and has such a low viscosity that foaming can be caused by an increase in the internal gas pressure with a rise in temperature. Since such conditions are mainly determined by the raw material composition, the degree of porosity is determined by adjusting the raw material composition. However, since the composition of industrial waste is unstable in the first place, it is not easy to adjust the raw material composition, and from this point, it is difficult to individually adjust various properties such as specific gravity.

As described above, it is difficult to individually adjust various characteristics such as specific gravity in the techniques of the first to third prior arts.
An aggregate having good properties in all of water absorption and strength was not obtained.

On the other hand, in the prior example 4, since the aggregate is formed by the disappearance of the burning of the crushed paper at the time of calcination, unlike the above first to third examples, the bone is merely adjusted by adjusting the amount of the crushed paper and the like. It is considered that the specific gravity of the material can be arbitrarily adjusted. However, according to the technique of the prior art example 4, since the crushed paper as the granulation nucleus is flexible and has a low specific gravity, it is not possible to obtain a good granulated product. Thus, only aggregates having high water absorption and low strength could be obtained.

On the other hand, in recent years, especially since the Great Hanshin Earthquake, buildings have been required to have seismic resistance that can withstand a large earthquake having a seismic intensity of about 7, so that not only the specific gravity of cement aggregate is low but also the water absorption. A material having low strength and high strength is required.

Therefore, the main problem of the present invention is firstly that:
In order to propose a low specific gravity, non-absorbent, and high-strength artificial lightweight aggregate, secondly, specific gravity, water absorbency and strength can be individually adjusted, and thus low specific gravity, non-absorbent, and An object of the present invention is to provide a method for producing an artificial lightweight aggregate capable of obtaining a high-strength artificial lightweight aggregate.

[0015]

Means for Solving the Problems Among the present invention which has achieved the above objects, the invention according to claim 1 is a sintered body mainly composed of industrial waste, and at least one or more of the sintered bodies are contained in the sintered body. And having a substantially non-porous coating layer covering the sintered body, having a specific gravity of 0.8 to
1.6, water absorption of 1.0% or less, crushing strength of 1 to 1.6
It is an artificial lightweight aggregate characterized by kN.

In this case, it is preferable to use at least one of tap water sludge, sewage sludge, and construction sludge as the industrial waste.

The artificial lightweight aggregate according to the present invention has at least one or more burn-off cavities while using industrial waste as a main raw material. The burning-dissipating cavities refer to cavities formed as traces of burning-disappearing objects contained in the granules before firing. Therefore, the burning-dissipating cavities are different from the cavities (hereinafter referred to as gas-foaming cavities) generated by gas foaming due to gas generation during firing in the conventional aggregate of industrial waste raw materials. In the present invention, the specific gravity can be reduced by the elimination cavities. Further, the artificial lightweight aggregate according to the present invention has a substantially non-porous coating layer covering at least the entire outer surface thereof. In the present invention, non-water absorption and high strength are mainly achieved by the non-porous coating layer. As a result, the artificial lightweight aggregate according to the present invention has a specific gravity of 0.8 to 1.6, a water absorption of 1.0% or less, and a crush strength of 1%.
It has low specific gravity, non-water-absorbing, and high strength in the range of ~ 1.6 kN.

According to a third aspect of the present invention, there is provided a method for producing an artificial lightweight aggregate by granulation and firing using industrial waste as a main raw material, wherein the non-flexible object substantially disappears by the firing. Is a granulation nucleus, and obtains a granulated material obtained by coating at least one or more of the granulated nuclei with the main raw material, and sinters the granulated material to obtain an aggregate. It is a manufacturing method.

In the method for producing an artificial lightweight aggregate according to the present invention, a non-flexible object which substantially disappears by firing is used as a granulation nucleus. Limitation to non-flexibility is essential to obtain good granules, and thus to improve non-water absorption and strength. The present invention is intended to obtain an aggregate by firing a granulated material obtained by coating such a granulation nucleus with a main raw material consisting of industrial waste, and the granulation nucleus substantially disappears at the time of sintering and remains on the trace. A cavity is formed. Therefore, in the present invention, the specific gravity can be arbitrarily adjusted without deteriorating the non-water-absorbing property and the strength by adjusting the size, the amount, and the like of the non-flexible object that substantially disappears by firing. The non-water absorption and strength can be adjusted by the method described below.

[0020] In this production method, in the granulation,
Drying the granulated product at least once or more is preferable in that the main raw material can be prevented from peeling off and falling off from the granulated product.

In these production methods, it is preferable that at least the outermost layer of the granulated material is formed only by a mixture of the main raw material and the raw material containing a high content of vitrified substance or only the raw material containing a high content of vitrified substance. As a result, the water absorption is reduced and the strength is improved. Also,
By adjusting the type and combination of the main raw material and the vitrified material-rich raw material, the thickness of the outermost layer, and the like, it is also possible to arbitrarily adjust the non-water absorption and strength.

Further, in these production methods, it is preferable to use at least one of the sewage sludge incineration ash, the fine powder of the sewage sludge burned material, and the fine powder of the construction sludge burned material as the industrial waste. It is preferable because it has advantages such as obtaining an improved composition.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. As a first embodiment of the artificial lightweight aggregate according to the present invention, first, one having a structure shown in FIG. 1 is proposed. That is, it is a substantially spherical sintered body 1 mainly composed of industrial waste, and has a burning-dissipating cavity 2a substantially at the center thereof.
The sintered body shell 3 is formed to cover the entire surface of the sintered body shell 3 (hereinafter, referred to as a non-porous coating layer 4). (Referred to as a coating layer). When a gas generating substance is contained in the industrial waste, a foamable microcavity 5 is formed in the sintered body shell 3 as shown in the figure.

As a second embodiment, as shown in FIG. 2, a plurality of burn-off cavities 2b are formed.
As a third embodiment, there is also proposed a structure in which a large number of fire-dissipating cavities 2c are formed as shown in FIG. The dashed line 6 in FIGS. 1 to 3 will be described later.

The artificial lightweight aggregate of the present invention having such a structure has a specific gravity of 0.8 to 0.8 due to the presence of the sinter-dissipating cavities.
1.6, and the water absorption is 1.0% or less and the crushing strength is in the range of 1 to 1.6 kN due to the presence of the non-porous coating layer.

Next, a method for producing an artificial lightweight aggregate according to the present invention will be described in detail. First, as the industrial waste used as the main raw material in the present invention, all of those known for the production of artificial lightweight aggregates can be used. In particular, from the viewpoint of obtaining a stable composition, etc. It is proposed to use one or more of sewage sludge and construction sludge. The construction sludge mentioned here includes sludge discharged from the construction site, that is, ash bentonite mud, waste mud due to the reverse method, high-moisture mud excavated soil (fine particles), and spring water discharged during construction. Includes sedimentation sludge separated, mixed sludge of groundwater, earth and sand and cement milk which may be generated in the soil cement method.

Other industrial wastes include so-called foundry mining wastes, such as cupola slag, cupola dust, cupola sludge, etc. discharged from a melting plant.
Sand processing waste sand, sand processing dust, etc.
Slags discharged from foundries, hydro-waste sand discharged from product factories, slag such as roll slag, molten metal processing slag, desulfurized slag, shell old sand, furan old sand, holo old sand, green old sand , Waste sand such as CO ₂ waste sand, shot blast dust,
Dust such as dust dust, shell sand dust, furan sand dust, green sand dust, etc., cement sludge, shot blast sludge, sludge such as wastewater treatment sludge, waste sludge, brick debris, etc., blast furnace slag, converter slag, etc. It is also conceivable to use slag, waste oil treatment sludge, oil refinery sludge, refined sludge, etc. in iron and steel making such as electric furnace slag. Further, from the viewpoint of optimizing the raw material composition, etc., two of the various industrial wastes described above are used.
It is also conceivable to use a mixture of species or more.

Pretreatment (drying, calcination, pulverization, classification, etc.) is performed on these industrial wastes as necessary to improve the subsequent granulation to obtain fine powder having an average particle size of 800 μm or less. Is preferred. Of course, average particle size 800
As long as it satisfies the condition of a fine powder having a size of μm or less, it can be directly used in a subsequent granulation step without performing pretreatment.

Of the water sludge, sewage sludge and construction sludge preferably used in the present invention, the water sludge is usually 40
Obtained as a dewatered cake containing 〜60 wt% water. Therefore, for example, after the water content of the water sludge dewatered cake is reduced to 10 to 30 wt% by a drying treatment, the cake is calcined at about 700 ° C. or more, and pulverized and classified to obtain a fine powder having an average particle diameter of 800 μm or less. Conceivable. Similarly, fine powder having an average particle size of 800 μm or less can be obtained by firing, pulverizing, and classifying construction sludge.

Unlike these, sewage sludge is usually incinerated in an incinerator at a sewage treatment plant and recovered as sewage sludge incineration ash. The average particle size of the sewage sludge incineration ash, depending on the type of incinerator, is about 10 to 10 when a fluidized incinerator is used.
100 .mu.m, about 40-800 .mu.m for a multi-stage oven or a single-stage oven combined with a dryer.

In these industrial wastes, SiO ₂ , Al
_In the case where the aggregate main component such as ₂ O ₃ is insufficient, the firing cost is reduced by lowering the firing temperature, the moldability is improved, the strength is improved,
For the purpose of adjusting the hue and the like, it is preferable to add a crushed product such as a viscosity, a porcelain, a stone or a glass product, or a natural fine aggregate such as silica sand, if necessary.

In the present invention, in addition to these industrial wastes, non-flexible objects which disappear by firing are used. In the present invention, those that do not substantially disappear by firing are as follows:
Ultimately, it remains in the aggregate and cannot be used because it is difficult to adjust or reduce the specific gravity of the aggregate, and a flexible material cannot be used because it makes the subsequent granulation extremely difficult.

The non-flexible object which disappears by firing according to the present invention has a softening point (a temperature at which a non-crystalline structure starts to soften), and has a softening point if it does not have a softening point. Organic polymers having a temperature at which the structure starts to melt) are all higher than room temperature, and are insoluble and non-swellable in water at room temperature. Here, the normal temperature in the present invention refers to an ambient temperature realized without performing heating or cooling in a granulation step described later.

In general, organic polymers are classified into natural polymers and synthetic polymers, and organic polymers contained in synthetic polymers are further classified into pure synthetic polymers and semi-synthetic polymers. , If it satisfies the above conditions such as softening point,
Any of natural, pure synthetic and semi-synthetic can be used in the present invention.

Examples of natural organic polymers include proteins, cellulose, natural resins, fats, polysaccharides and the like.
As the pure synthetic polymer, a hard rubber having a very low rubber elasticity among the synthetic rubbers in addition to various synthetic resins can be considered. In addition, as semi-synthetic polymers, cellulose derivatives (eg, celluloid, cellulose acetate), natural rubber plastics (eg, ebonite), protein plastics (eg, milk casein plastic, soy casein plastic), Natural resin derivatives (eg, cured rosin) are conceivable.

The following are chemically classified synthetic resins particularly suitable for the present invention. (1) Polymerizable resin a) Unsaturated polymerizable resin Hydrocarbon resin: polyethylene, polypropylene,
Polybutenes, polystyrenes, terpene resins, petroleum resins, etc. Acrylic resins: polyacrylates, polymethacrylates, polyacrylonitriles, etc. Vinyl acetate resin derivatives: formal resins, acetal resins, butyral resins, etc. Halogen containing resins: polychlorinated Vinyl, polyvinylidene chloride, etc. Aldehyde-based polymer: polyoxymethylene, etc. b) Ring-opening polymerization type resin Lactam polymer: 6-nylon, etc. Polyether: penton resin, etc. Polyalkyleneimine: polyethyleneimine, etc. (2) Condensation Polymerization type resin a) Addition condensation type resin Phenol resin and homologues Amino resin: urea resin, melamine resin, aniline resin, amide resin, etc. Metaxylene resin, toluene resin, ketone resin b) Polycondensation type resin Polyester resin: saturated alkyd Resin, te Phthal resin, unsaturated polyester resin, allyl resin, polycarbonate, etc. Polyamide resin: 6-nylon, 66-nylon, homologous nylon, etc. Ether type resin: Polyethers, etc. Furan resin (3) Addition polymerization type resin a) Multi-addition Type resin: rigid polyurethane, polyurea, etc. b) Ring-opening addition type: epoxy resin, etc. (4) Ion exchange resin a) Cation exchange resin b) Anion exchange resin These synthetic resins may be used alone or in combination of two or more. It can be used as a mixture, and easily becomes a non-flexible synthetic resin molded article suitable for the present invention by an ordinary molding method. That is, as described below, the non-flexible object of the present invention is preferably used after being classified into a lump (including a spherical shape), a granular body, and a powder. When a synthetic resin is used, the lump and the relatively large size are used. Large particles can be easily obtained by molding methods such as injection molding, compression molding, and extrusion molding (including a cutting function). For relatively small particles and powders, agglomerates and relatively large particles can be obtained. It can be easily obtained by crushing and classifying a large granular material. The shape of the synthetic resin molded body is not limited as long as it is a non-flexible resin (including a composition) made of the above-described synthetic resin. It may be a lump shaped body, a sheet, a container, or the like, or a crushed product thereof.
These raw materials to be crushed may be commercial products or wastes. However, structures or forms such as fibers, films (including papers), and the like, and crushed products thereof exhibit flexibility depending on the structure or form itself, and therefore cannot be applied to the present invention. .

Among such synthetic resin molded products, those having a low specific gravity as a foam can be suitably used in the present invention because they have high sintering disappearance and are relatively inexpensive. For example, among two-component foams such as polystyrene-based resin foams, acrylic-based resin foams, and urethane-urea-based foams, resin foams that are generally classified as rigid (that is, non-flexible) are used. The expansion ratio is about 2-5
A value of 0 is suitable for the present invention. In particular, polystyrene-based resin foam is widely used as a cushioning material for packaging instant noodle cups and broken items, and the largest amount of this type of resin foam is discarded.
It is preferable because there is no shortage in procurement of raw materials. In the case of a non-flexible resin which is not a foam, the specific gravity is large and granulation is easy. However, depending on the firing conditions (temperature and time), the resin remains in the aggregate, and the specific gravity of the aggregate is reduced to a desired low specific gravity. Care must be taken because adjustment may not be possible.

The size of the non-flexible object may be appropriately determined according to the desired aggregate size, the internal structure of the aggregate, and the specific gravity of the aggregate. For example, an aggregate generally used when a resin foam is used is used. Considering the size (diameter 4 to 25 mm), one or two of a lump (including a sphere) having an average particle size of 7 to 20 mm, a granular material having an average particle size of 1 to 7 mm, and a powder having an average particle size of 1 mm or less. It is preferred to use a mixture of more than one species depending on the desired internal structure and specific gravity. Some of the waste such as the cushioning material of the package can be directly used as such a lump, but if not, it is necessary to obtain a desired size and shape by crushing and classification.

Here, as an example of a method of crushing a non-flexible resin foam, a method of cutting and crushing by rotating a cutter blade in water and pressing the foam against the cutter blade is proposed. The advantages of cutting and crushing in water include the point that the cut pieces do not form a bridge and hinder the contact of the material with the rotating cutter blade. Thus, the foam is not melted, and the cut and pulverized foam quickly floats on the water surface, so that the foam can be easily separated and collected. The size and shape of the pulverized product obtained by this method can be adjusted by the size and expansion ratio of the foam as the pulverized raw material, the shape and rotation speed of the rotary cutter blade, the pressing force of the foam to the cutter blade, the pressing time, and the like. . Then, by classifying the obtained pulverized product, a foam having a desired size can be obtained.

Next, the above-mentioned tap water sludge and construction sludge are calcined.
The main raw materials are fine powder with an average particle size of 800 μm or less and sewage sludge incineration ash (hereinafter referred to as sludge fine powder) obtained by pulverization and classification. The production process of the present invention will be described in detail by taking as an example a case where a non-flexible resin foam having the size described above is used as a granulation core.

"Example of granulation when non-flexible resin foam is powder or granule"<Example of granulation by extrusion granulation method> A non-flexible resin foam of powder or granule is stirred in a stirring vessel. And spraying or spraying water or an aqueous solution of an organic polymer, an emulsion or a suspension (hereinafter referred to as a molding binder) on the non-flexible resin foam while stirring. . When the surface of the foam is uniformly and sufficiently wet with the molding binder, only the supply of the molding binder is stopped, and while the stirring is continued, the sludge fine powder is sprayed to uniformly mix the foam and the sludge fine powder. The application of the sludge fine powder is stopped when the sludge fine powder in the mixture becomes a dry state.
Thereafter, the granulating mixture having a desired uniform composition can be obtained by alternately repeating the spraying of the forming binder and the spraying of the sludge fine powder as necessary. The composition of the granulation mixture is preferably from 25 to 60 parts by weight of a molding binder with respect to 100 parts by weight of sludge fine powder, and the foam is preferably from 15 to 60 vol% of the whole mixture. .

The mixture thus obtained is formed into cylindrical pellets having a diameter of 3 to 16 mm by an extrusion granulator, and then spheroidized by a granulator (having a particle diameter substantially equal to the diameter of the cylindrical pellets). By applying the method described above, it is possible to obtain a granulated material in which a large number of powders or a plurality of granular non-flexible resin foams are completely covered with sludge fine powder. Examples of the extrusion granulator include, for example, a vacuum extruder “VZID type” (manufactured by Honda Iron Works),
Pre-extrusion type granulator “Pelletter Double” (manufactured by Fuji Paudal Co., Ltd.) can be mentioned, and as the granule sizing machine, for example, “Malmerizer” (manufactured by Fuji Paudal Co.) which is a high-speed rolling type Can be mentioned.

The molding binder is composed of water or an aqueous solution, emulsion or suspension of water and an organic polymer as described above. Examples of the aqueous solution of the organic polymer include vinyl acetate and the like. Emulsions of vinyl monomers, aqueous solutions of synthetic polymers such as copolymers of conjugated dienes and maleic anhydride represented by polyvinyl alcohol, polyethylene glycol, butadiene, etc., as well as natural starches such as aqueous starch and agar An aqueous solution of a molecule and an emulsion of various proteins such as milk are conceivable. Regarding the concentration of this organic polymer,
There is no particular limitation, but 10 wt% or less is desirable from the viewpoint of economy. The use of these molding binders not only enhances the shapeability during granulation, but also has the effect of assisting in maintaining the shape of the granulated material in the drying step described below. In particular, when a molding binder containing an organic polymer is used, the shape retention of the dried granules is also increased, so that subsequent handling and the like become easy.

<Example of Granulation by Rolling Granulation Method> Examples of the apparatus used in the rolling granulation method include a rotating dish type, a rotating drum type, and the like. That is, a mixture of a powdery or granular non-flexible resin foam and sludge fine powder is quantitatively supplied to a rotating dish having an inclined arrangement, and a molding binder is sprayed or sprayed in an amount required to form a sphere. I do. While agglomerates of the mixture are generated by the molding binder sprayed or the like, the agglomerates and the mixture are carried toward the highest position with the rotation of the rotating plate, and the agglomerates mainly roll below the rotating plate due to gravity. By doing
Adhesion of the sludge fine powder to the surface of the agglomerate proceeds to form granules.

The average composition of the granulated product obtained by the tumbling granulation method is preferably 35 to 70 parts by weight of the forming binder with respect to 100 parts by weight of the sludge fired body, and the foam concentration is the volume concentration of the whole mixture. It is preferably 15 to 50 vo1%. Examples of the rolling granulator include a dish-shaped granulator such as a TB granulator (manufactured by Tobu Seisakusho).

"Example of granulation when the non-flexible resin foam is a lump (average particle size: 7 to 20 mm)" The lump of the inflexible resin foam is put into a stirring vessel and stirred. Spray or spray the molding binder. When the surface of the foam is uniformly and sufficiently wet, only the application of the molding binder is stopped, and while the stirring is continued, fine powder of sludge is sprayed to uniformly adhere to the surface of the foam. Thereafter, the adhering layer of the sludge fine powder is grown by alternately repeating the application of the forming binder and the spraying of the sludge fine powder.

When the adhered layer has grown to the target thickness, the operation is terminated, and a granulated material containing a lump of non-flexible resin foam at substantially the center is obtained. In this case, the sludge fine powder adhering to the foam surface is likely to peel off and fall off, so care must be taken. As a method for this, for example, when the sludge fine powder is attached to the foam surface so thinly that it does not peel or fall off,
It is conceivable that the adhered layer is solidified by drying once at a temperature (preferably about 70 ° C. or less) at which the foam does not soften or melt with respect to the granulated product. Thereafter, the foam is covered with the sludge fine powder by alternately repeating the application of the forming binder and the spraying of the sludge fine powder in the same manner as described above. Of course, the foam may be covered with the sludge fine powder by repeatedly performing the spraying of the sludge fine powder and the drying treatment such as the spraying of the molding binder, and the drying of the granulated product a plurality of times.

Further, unlike such a granulation example, it is preferable to use a rolling granulation method. However, when the foam is a lump (average particle size of 7 to 20 mm), it is preferable to use a method different from the above-described rolling granulation method. That is,
After supplying only a lump of non-flexible resin foam to a rotating dish, the rotating dish is rotated to spray or spray a molding binder to uniformly wet the foam, and then, while continuing to rotate, the sludge fine powder is removed. Spray. The sludge fine powder sprayed by the rolling of the foam on the rotating plate is uniformly attached to the foam surface. When the adhering surface of the sludge fine powder has dried, supply of the sludge fine powder is stopped. Thereafter, the granulation is performed by alternately repeating the spraying of the molding binder and the spraying of the sludge fine powder to increase the adhesion layer of the foam sludge fine powder. In particular, after the drying treatment, it is preferable to grow the adhered layer of the sludge fine powder by the tumbling granulation method. Also in this case, the above-mentioned TB granulator can be used.

In the case of granules produced by the extrusion granulation method and the tumbling granulation method described above, if there is a possibility that the granules adhere to each other, for example, in addition to the sludge fine powder, it will be described later. It is desirable to attach a dry powder, such as a mixture of sludge fine powder and vitrified substance-rich fine powder, or a powder consisting only of vitrified substance-rich fine powder, to the surface of the granulated material. In particular, in the extrusion granulation method described above, it is desirable to attach a dry powder to the pellets before the sizing treatment.

"Another embodiment of granulation" The granulated material thus granulated is dried and fired to obtain an artificial lightweight aggregate having the structure shown in Figs. 1 to 3 described above. . However, in this case, the non-porous coating layer may not be sufficiently formed, and the strength and the non-water absorbing property may not be sufficient.
In addition, a case where a non-water-absorbing aggregate having higher strength is produced is also considered. In such a case, according to the invention of claim 5, it is preferable that at least the outermost layer of the granulated material is formed only by a mixture of the sludge fine powder and the vitrified substance-rich fine powder or only the vitrified substance-rich fine powder. desirable. Of course, all of the layers of the sludge fine powder of the granulated material may be a mixture of the sludge fine powder and the vitrified substance-rich fine powder or the layer of only the vitrified substance-rich fine powder. As a result, the vitrified substance in the sludge fine powder can be supplemented, and the firing cost can be reduced by shortening the firing time. There is no particular limitation on the amount of the fine powder having a high content of vitrified substance, but it is preferably 50% by weight or less in all the outermost layer raw materials when the fine glass powder described later is used.

As the fine powder having a high content of vitrified material, any material having a chemical composition or a crystalline material which is easily vitrified as a main component can be used as a raw material. A fine powder of vitrified material mainly containing an oxide) containing 60 wt% or more of ₂ is preferable, and a glass fine powder is particularly preferable. The glass fine powder referred to here can be easily obtained by, for example, crushing and grinding a so-called glass product (including a glass material). Examples of the glass products include commercially available glass products such as window glass, glass bottles, and electric bulbs, and it is particularly preferable to use wastes of these commercially available glass products from the viewpoint of recycling, economy, and the like. Translucent or opaque glassware can also be used. As for the size of the glass fine powder, generally, the larger the particle size, the longer the time required for melting to start.
It is preferably less than μm. As a method of pulverizing the glass product, a method of pulverizing and grinding while mixing the sludge fine powder and the glass product in addition to a method of pulverizing and grinding the glass product alone can be considered.

As the method for forming the outermost layer, pellets obtained by extrusion granulation, granules subjected to sizing treatment, or granules obtained by tumbling granulation are used as new granulation nuclei (hereinafter referred to as primary granules). Granules), and the primary granulated product is granulated by covering only with a mixture of sludge fine powder and vitrified substance-rich fine powder or with vitrified substance-rich fine powder alone, thereby forming the outermost layer. A method for obtaining the formed final granules is conceivable. The formation of this outermost layer
It is preferable to use the rolling granulation method when the above-mentioned foam is a lump.

When the foam is a lump, the manufacturing process up to the final granulated product having the outermost layer formed by the above-described tumbling granulation method can be performed consistently. That is, in the above-described tumbling granulation method, granulation may be performed in the middle of granulation by replacing the sludge fine powder with a mixture of the sludge fine powder and the vitrified substance-rich fine powder or the vitrified substance-rich fine powder. .

The thickness of the outermost layer varies depending on the size of the target final granulated product, the structure / dispersion state of the foam in the granulated product, and the size, specific gravity, strength, water absorption and the like of the aggregate. Preferably, it is in the range of about 0.7-6 mm to provide sufficient strength of the aggregate. When the outermost layer is formed, it is needless to say that the thickness of the sludge fine powder adhering layer must be subtracted by the thickness of the outermost layer during granulation.

The final granulated product thus obtained has the structure shown in FIGS. That is, the final granulated material 7 shown in FIG.
And the layer 9 composed of fine sludge powder is the outermost layer 1
0. The final granulated material 7 shown in FIG. 5 is obtained by covering a plurality of resin foams 8b, 8b... With a layer 9 composed of sludge fine powder, and further covering the layer 9 composed of sludge fine powder with an outermost layer 10. . Final granulated material 7 shown in FIG.
Are covered with a layer 9 made of fine sludge powder, and a layer 9 made of fine sludge powder is coated with an outermost layer 10. In FIGS. 4 to 6, reference numeral 6 denotes a boundary inside the outermost layer, but it does not always have a clear boundary in reality.

"Firing" The final granulated product (including the granulated product in the case where the outermost layer is not formed) is then transferred to a drying process followed by a firing process. Depending on the structure and performance of the kiln, it is possible to perform the drying and baking steps (including preheating, baking, and cooling) continuously in the kiln. For this purpose, it is desirable to perform drying before firing separately. The drying temperature in the drying step is desirably maintained at a temperature equal to or lower than the temperature at which the inflexible resin foam inside the final granule starts softening or melting. When the temperature is higher than this temperature, cavities are formed in the granulated material due to the shrinkage of the foam and the strength is reduced, and the granulated material can sufficiently withstand handling such as transportation when moving from the drying process to the firing process. May not be possible.

The drying temperature varies depending on the type of the inflexible carrier resin, but is preferably as follows. Polystyrene-based resin: 60 to 70 ° C Acrylic-based resin: 80 to 90 ° C Urethane and urea-based hard foam: 90 to 110 ° C The dried final granulated material is subsequently fired to become an artificial lightweight aggregate. . That is, artificial lightweight aggregates having the structures shown in FIGS. 1 to 3 are obtained from the final granules shown in FIGS. 4 to 6 described above. As is clear from this correspondence, the alternate long and short dash line 6 shown in FIGS. 1 to 3 corresponds to the inner boundary of the outermost layer shown in FIGS. However, basically, a clear boundary does not occur in the aggregate.

Here, the firing temperature is 1000 to 1250 ° C.
Is preferably within the range. The firing time is preferably 3 hours or more. There are no particular restrictions on the kiln used for firing, but various types of continuous kilns (bogie type tunnel kiln, roller hearth kiln, mesh belt kiln, slab pusher kiln, walking beam kiln, counter travel kiln, and small tunnel kiln) Micro-kilns, etc., and intermittent furnaces (such as heavy oil-fired or gas-fired shuttle kilns, intermittent tunnel kilns) can be used.

If there is a possibility that the final granulated products and the final granulated product and the firing container may be fused in the firing process, a powder that does not start melting even at the highest temperature of the firing process, for example, silica stone powder, is used in advance. To the final granulated surface,
By laying on the surface of the firing vessel, fusion can be prevented.

The artificial lightweight aggregate manufactured in this way is suitable for reinforced concrete of a building with high earthquake resistance, which satisfies the following quality targets. Specific gravity: 0.8 to 1.6 Water absorption: less than 2.0% Crushing strength: 1.0 kN or more (Spherical body having a diameter of 20 mm, crushing strength obtained by a compression test at a pressing speed of 1 mm / min, JISZ88
41 (based on the granulated material-one strength test method) Shape: spherical, 4 to 25 mm in diameter In particular, in the production method according to the present invention, the shape of the non-flexible substance,
The specific gravity can be freely adjusted according to the size and amount used,
The water absorption and the crushing strength can be adjusted depending on the raw material composition and thickness of the outermost layer. Hereinafter, the effects of the present invention will be clarified by showing examples.

EXAMPLE An artificial lightweight aggregate was actually manufactured by the manufacturing method according to the present invention, and its specific gravity, water absorption, crushing strength and the like were evaluated. Further, the properties of the artificial lightweight aggregate according to the present invention and the aggregate manufactured by the conventional manufacturing method were compared.

As main raw materials, tap water sludge, sewage sludge incineration ash, and construction sludge (excavated effluent from the reverse method) were used. For tap water sludge and construction sludge, each dewatered cake is baked at 700 ° C and then crushed and classified to have an average particle size of 800μ.
m or less fine powder was obtained. Tables 1 and 2 show the compositions of the dewatered sludge cake, Table 3 shows the dehydrated sewage sludge cake and its incinerated ash, and Table 4 shows the composition of the dehydrated construction sludge cake.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

As the glass fine powder, used fluorescent lamps (for general household use, including an opacifying agent) were thrown into a grinding tank of an Ishikawa-type stirring crusher (manufactured by Ishikawa Factory), and then split. ,
Activate the stirring crusher and pulverize, then pulverize,
A fine powder having an average particle diameter of 12 μm was used.

Examples 1 to 18 Table 5 shows the conditions for producing the artificial lightweight aggregates of Examples 1 to 18. The mixing ratio of the glass fine powder in Table 5 is the weight ratio of the glass fine powder to all the raw materials for the outermost layer.

[0069]

[Table 5]

The sludge fine powders X1, X2 and X3 in Table 5 are:
Each is as follows. X1: Sewage sludge incineration ash (furnace outlet product shown in Table 3) with an average particle size of 45 μm. X2: Bake the water dewatered cake (900 dried products in Table 1)
(Calcined at 1 ° C. for 1 hour) and pulverized, and has an average particle size of 32 μm. X3: A fine powder obtained by baking (drying the dried product in Table 4 at 1000 ° C. for 1 hour) and pulverizing a dewatered cake of construction sludge (excavated discharge from the reverse method), and having an average particle size of 12 μm.

The inflexible resin foams Y1, Y2,
Y3 is as follows.

Y1: A block of expanded polystyrene (a 30-fold foam used as a cushioning material in packaging) is cut, pulverized and classified to obtain an average particle size of 10.2, 3.5, 0.
Non-flexible foam of three sizes of 8 mm. Y2: Acrylic resin foaming foam—A 6-fold foam obtained by adding and mixing foaming agent vinyl hole DW # 6 (manufactured by Eiwa Kasei Kogyo Co., Ltd., main component: azodicarbonamide) to methacrylic resin powder and heating and foaming. ｝ Are non-flexible foams having three average sizes of 8.5, 2.3, and 0.5 mm, which are obtained by cutting, pulverizing and classifying｝. Y3: rigid urethane foam: a part of a polyol in which polyhydric alcohol (mainly ethylene glycol) is condensed with adipic acid to add an OH group to a terminal, and 4,4-diphenylmethane diisocyanate (trade name: Desmodur M) To
A prepolymer is prepared by reacting in advance, and the remaining polyol, a mixture of water, a catalyst (triethylamine), and a dispersion stabilizer (silicone oil) are added thereto. It is a non-flexible foam having three average sizes of 8.8, 2.6, and 0.4 mm, which is obtained by cutting, pulverizing and classifying.

Molding binders Z1, Z2, Z3 in Table 5
Are as follows. Z1: emulsified water (solid content: 3%) composed of vinyl acetate laundry paste. Z2: polyvinyl alcohol aqueous solution (solid content concentration 2%)
It is. Z3: Starch aqueous solution (solid content concentration 4%).

<Production of Primary Granules of Examples 1 to 18> When the average particle size of the resin foam exceeds 7 mm (Example 1,
4, 7, 10, 13) Using a TB granulator (TB-G6 type) manufactured by Tobu Corporation,
Example 1 according to the compounding amount shown in Table 5 for each resin foam,
In the case of 4, 7 4g, in the case of Example 10, 20g, Example 1
In the case of 3, 30 g is weighed and supplied to the rotating plate, and the rotating plate is
While rotating at 5 rpm, each of the molding binders shown in Table 5 was sprayed to uniformly and sufficiently wet the foam. While continuing rotation, each sludge fine powder (in a dry state) shown in Table 5 was sprayed to uniformly adhere to the foam surface. When the adhering weight of the sludge fine powder has reached about a predetermined half, in order to prevent the adhering layer from peeling off and falling off, the surface of the adhering layer is once half-dried by rotating and exposing it to hot air of 45 ° C. The adhesion layer was grown to a predetermined weight by repeating the wetting by spraying the molding binder and the spraying of the sludge fine powder. This weight was determined based on the consumption of each raw material. That is, the molding binder was 35 in Examples 1 and 4.
0 g, 380 g in Example 7, and 400 in Example 10.
g and Example 13 consumed 300 g, respectively, and 1000 g of the sludge fine powder was consumed as foam adhering matter in all Examples. The average diameter of the primary granules thus obtained was 14.1-16.5 mm as shown in Table 5, respectively.
Met.

When the average particle size of the resin foam is 7 mm or less (Examples 2, 3, 5, 6, 8, 9, 11, 12, 14 to
18) As a mixing device, an MTI universal mixer EM25B type manufactured by Tsukishima Plustech Co., Ltd. was used. According to the compounding amounts shown in Table 5, each resin foam was 16 g in Examples 2, 5, and 8, 20 in Examples 3, 6, 9, 16, and 17.
g, 100 g in Examples 11, 12, and 18, and Example 1
In the case of No. 4, 120 g was weighed, and in the case of Example 15, 160 g was weighed and supplied to a mixing tank (capacity: 30 l). The rotation speed of the mixing agitator is 125 rpm and the rotation speed of the chopper is 7
Each of the molding binders shown in Table 5 is sprayed while stirring at a setting of 40 rpm to uniformly and sufficiently wet the resin foam, and then each sludge fine powder (dry state) of Table 5 is sprayed while stirring is continued. And uniformly mixed with the resin foam.

Sprinkle the fine sludge powder with a predetermined amount of 60
When it reaches ~ 70%, stop and continue stirring.
Each of the molding binders was sprayed and added to each predetermined amount.
The final blending amount of the molding binder was as described in Examples 2, 3, 5,
1400 g in the case of 6, 18; 152 in the case of Examples 8 and 9
0 g, 1600 g in Examples 11 and 12, Example 1
1200 g in the case of 4, 15 and 1 in the case of Examples 16 and 17
320 g. When the wetness became uniform, spraying of the sludge fine powder was resumed and added to a predetermined amount. The final blending amount of the sludge fine powder is 4000 g in all of Examples 1 to 18. The mixture thus obtained is granulated in a vacuum-free state using a vacuum extruder (VZID type) manufactured by Honda Iron Works,
A cylindrical pellet having a diameter of about 3 to 15 mm was obtained. The extrusion hole size of the die applied to the vacuum extruder was as described in Examples 2, 5,
8 and 14 for 14 mm, Examples 6 and 11 for 12 mm,
In the case of Examples 3, 15, and 18, 3 mm, and in Examples 12, 16,
In the case of 17, it is 8 mm.

The obtained cylindrical pellets were subsequently made spherical using a “Malmerizer” manufactured by Fuji Paudal to obtain primary granules. The primary granules in each example exhibited the average diameters shown in Table 5.

<Formation of the outermost layer>
As shown in Table 1, in Examples 1 to 15, the same sludge fine powder as used for the primary granulated product was used, and in Examples 16 to 18, a different powder from that used for the primary granulated product was used. In Examples 1 to 3 and 16, only the sludge fine powder was used.
In Examples 15, 17, and 18, a mixture of glass fine powder and the above-mentioned sludge fine powder in the composition shown in Table 5 was used. The mixing conditions include MT manufactured by Tsukishima Plustech Co., Ltd.
Using an I Universal Mixer Model EM25B, the mixing agitator rotation speed was 250 rpm, the chopper rotation speed was 1480 rpm, and the mixing time was 2 minutes.

For the formation of the outermost layer, the above-mentioned TB granulator (TB-G6 type) manufactured by Tobu Seisakusho was used. The mixing ratio of the glass fine powder in each example is as shown in Table 5, and the charged amount of the granulated material in the rotating plate of the granulator was 1000 g in all examples. While rotating the rotating plate at 25 rpm, the same molding binder used for the production of the granulated material is sprayed to uniformly wet the granulated material, and the raw material for each outermost layer in the dry state having the composition shown in Table 5 is mixed. Was sprayed to uniformly adhere to the surface of the granules. The amount of the molding binder consumed in forming the outermost layer was 200 to 220 in each of the examples.
g. Each of the obtained final granules in the undried state completely contained the resin conjugate, and the average thickness of the outermost layer was 1.2 to 3.3 as shown in Table 5. Was.

<Drying and firing of final granulated product> The final granulated product was dried under the following conditions using a dryer (ONDO) manufactured by Temperature Equipment Laboratory Co., Ltd. Examples 1 to 9, 16 and 17: 65 ° C., 3 hours Examples 10 to 12, 18: 85 ° C., 2 hours Examples 13 to 15: 95 ° C., 2 hours Subsequently, using a muffle furnace (KDF P-90) manufactured by Denken Co., Ltd., in all examples, the firing time was set to 4 hours in an air atmosphere, and Table 5 was used.
Was fired at each temperature shown in FIG.

<Evaluation of Aggregate> The average diameter, specific gravity, water absorption and crushing strength of the manufactured lightweight aggregate were measured. Table 6 shows the results.

[0082]

[Table 6]

As is clear from Table 6, the lightweight aggregate prepared by the production method of the present invention has a specific gravity of 0.8 to 1.6, a water absorption of 1.0% or less, and a crushing strength of 1.0 kN or more. ,
It has all the properties of low specific gravity, non-water absorption and high strength.

[Comparative Examples 1-3] In Examples 1-3,
Without using a resin foam in the production process of the primary granulated product, only the sewage sludge incineration ash and the forming binder, except that the primary granulated product having the same average diameter as each of the examples was granulated. Aggregates were produced under the same conditions. As a result, the manufactured aggregate had a specific gravity in the range of 1.6 to 1.7, and did not fall within the specific gravity range targeted by the present invention.

"Comparative Examples 4, 5, 6"
In 12, without using water in the production process of the primary granulated product,
Granulation was attempted under the same conditions as in each example except that a dewatered cake of sewage sludge was used instead of the sewage sludge incineration ash (the water content was 40 parts per 100 parts by weight of sludge solids). However, a primary granulated product containing a resin foam inside could not be produced.

Comparative Example 7 An aggregate was produced under the same conditions as in Example 7 except that the step of forming the outermost layer was omitted. The crushing strength of the obtained aggregate was 0.64.
At kN, the strength was insufficient.

Comparative Example 8 An aggregate was produced under the same conditions as in Example 8 except that the step of forming the outermost layer was omitted. The crushing strength of the obtained aggregate was 0.75.
At kN, the strength was insufficient.

Comparative Example 9 An aggregate was produced under the same conditions as in Example 9 except that the step of forming the outermost layer was omitted. The crushing strength of the obtained aggregate was 0.83.
At kN, the strength was insufficient.

[0089]

As described above, according to the present invention, an artificial lightweight aggregate having low specific gravity, non-low water absorption and high strength can be obtained, and specific gravity, water absorption and strength can be individually adjusted. Therefore, various advantages are brought about, such as a method for producing an artificial lightweight aggregate capable of obtaining an artificial lightweight aggregate having a low specific gravity, a non-water-absorbing property and a high strength.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a first embodiment of an artificial lightweight aggregate according to the present invention.

FIG. 2 is a longitudinal sectional view schematically showing a second embodiment of the artificial lightweight aggregate according to the present invention.

FIG. 3 is a longitudinal sectional view schematically showing a third embodiment of the artificial lightweight aggregate according to the present invention.

FIG. 4 is a longitudinal sectional view schematically showing a first embodiment of the final granulated product.

FIG. 5 is a longitudinal sectional view schematically showing a second embodiment of the final granulated product.

FIG. 6 is a longitudinal sectional view schematically showing a third embodiment of the final granulated product.

[Explanation of symbols]

1: Artificial lightweight aggregates, 2a to 2c: Burnable vanishing cavities, 3:
Sintered shell, 4: non-porous coating layer, 5: foamable cavity, 6: inner boundary of outermost layer, 7: final granulated product, 8: resin foam, 9 ...
Layer composed of sludge fine powder, 10 ... Outermost layer.

Claims (6)

[Claims] 1. A sintered body mainly composed of industrial waste,
The sintered body has at least one or more sinterable cavities and a substantially non-porous coating layer covering the sintered body, and has a specific gravity of 0.8 to 1.6 and a water absorption of 1 An artificial lightweight aggregate having a crushing strength of 1.0 kN or less and a crushing strength of 1 to 1.6 kN. 2. The artificial lightweight aggregate according to claim 1, wherein at least one of water sludge, sewage sludge and construction sludge is used as the industrial waste. 3. A method for producing an artificial lightweight aggregate by granulation and firing using industrial waste as a main raw material, wherein the non-flexible object substantially disappearing by the firing is a granulation nucleus, and at least one or more granules are formed. Obtaining a granulated product obtained by coating the granulated nucleus with the main raw material, and firing the granulated product to obtain an aggregate. 4. The method for producing an artificial lightweight aggregate according to claim 3, wherein the granulated product is dried at least once during the granulation. 5. The artificial lightweight aggregate according to claim 3, wherein at least the outermost layer of the granulated material is formed only by a mixture of the main raw material and the raw material with a high content of vitrified material or only the raw material with a high content of vitrified material. Manufacturing method. 6. The incinerated sewage sludge as the industrial waste,
The method for producing an artificial lightweight aggregate according to any one of claims 3 to 5, wherein at least one of a fine powder of a fired water sludge and a fine powder of a fired construction sludge is used.