JPH07124535A - Curing/coagulating agent of incineration ash and production of building material - Google Patents

Abstract

PURPOSE:To achieve a cost reduction and to obtain high hardness by using a compsn. based on cement and containing lignosulfonate, lime, gypsum and silicate as auxiliary agents as a curing/coagulating agent curing and coagulating incineration ash in order to reutilize incineration ash as aggregate of a building material. CONSTITUTION:As a curing/coagulating agent curing and coagulating the so- called fly ash being the fine powdery coal ash discharged from a steam power plant and the incineration ash discharged from a garbage incinerator in order to reutilize both of them as aggregate of a building material, a compsn. based on cement, containing lignosulfonate as a dispersing and fluidizing agent/water reducing agent and further containing lime/gypsum and silicate as a curing accelerating agent as auxiliary agents mixed with cement is used. This curing/ coagulating agent is mixed with incineration ash and the mixture of the curing/ coagulating agent and incineration ash are cured and coagulated to produce a desired building material. As silicate, aluminum silicate is pref. used. By this constitution, a building material having a high hardness is obtained at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention cures so-called fly ash, which is fine coal ash discharged from a thermal power plant, combustion ash discharged from a refuse incinerator, and various combustion ash such as volcanic ash ejected by a volcanic eruption. The present invention relates to a hardening coagulant of combustion ash for coagulating and reusing the combustion ash as an aggregate of a building material, and a building material manufactured using the hardening coagulant.

[0002]

2. Description of the Related Art Conventionally, fly ash collected from a flue gas of a pulverized coal combustion boiler with a dust collector, combustion ash discharged from a refuse incinerator, and volcanic ash are partially dumped to a landfill site. However, this type of method is also a limited processing method. Therefore, combustion ash that cannot be properly treated and processed is becoming a problem as a cause of dust pollution.

Therefore, recently, various studies and examinations have been made on the treatment and utilization method of combustion ash, and as a typical example, the idea of effectively reusing combustion ash as an aggregate of building materials. Is proposed.

[0004]

However, there are the following problems in reusing various combustion ash as an aggregate of building materials. That is, the surface shape of the ash burned at a high temperature, as represented by fly ash, is spherical like a bearing. For this reason, inexpensive Portland cement (hereinafter simply referred to as "cement") is used as a curing agent, and the combustion ash is hardened and coagulated. Need. As a result, the manufacturing cost of the building material is increased, and commercialization is impossible. On the other hand, there is a problem that strength development is difficult with the same amount of cement used as ordinary concrete.

Further, in order to reuse the combustion ash as a building material, various conditions required for each building material must be satisfied. Specifically, taking a sidewalk block as an example, the required compressive strength is 50 kgf / cm ² or more, and the water absorption rate is within 10%. Must be a product. Therefore, since the combustion ash can be reused only after satisfying these conditions, the advent of a hardening coagulant for combustion ash that satisfies all these conditions has been desired.

Conventionally, there is a method of adding an emulsified synthetic resin to the combustion ash as a coagulation method which is generally considered to express high strength. It is not available at a high price. In addition, there are methods such as gypsum hardening method, lime hardening method, and water glass hardening method, which are partially used in civil engineering and construction work. However, although these methods are low in price, there is a problem that the aggregate to be reused cannot reach the required strength and cannot be used.

The remaining low cost method is to use common cement. However, according to the experiments conducted by the inventor, a mixing amount of 1 or more cement is required for 1 aggregate in order to develop the strength of cement alone. Therefore, no matter how cheap the cement is, it is not a method that can be cost-effectively adopted.

The present invention has been made by paying attention to such a conventional problem, and when reusing combustion ash as a building material, it can be hardened and condensed by using a minimum necessary amount of cement, Curing ash curing coagulant that can reduce costs, meet various conditions required for each building material, and also contribute to the treatment of combustion ash, which will become an increasingly social problem in the future. , And a method for manufacturing a building material.

[0009]

The gist of the present invention for attaining the above object is to provide a combustion method for hardening and condensing various combustion ash and reusing the combustion ash as an aggregate of a building material. An ash-hardening coagulant, which is cement as a main component, and a lignin sulfonate as a dispersant / water-reducing agent, and lime, gypsum and silicate as a hardening accelerator, which are mixed in harmony with the main component. It exists in a hardening coagulant of combustion ash characterized by being formed as.

Another aspect of the present invention is that the hardened coagulant is mixed with combustion ash, and a mixture of the hardened coagulant and combustion ash is hardened and solidified. It lies in the method of manufacturing the material.

As described above, the present invention is a hardening coagulant or the like which uses cement as the main ingredient, but it is possible to harden and coagulate by using the minimum necessary amount of cement, and the cost can be greatly reduced. Is. That is, a predetermined auxiliary agent is added to an aggregate such as fly ash which is made spherical and has no tackiness, and promotes the hardening and setting reaction of the added cement to develop high hardness.

In the present invention, it is a condition that all the substances to be added should be substances that do not cause damage to animals and plants and do not cause primary pollution or secondary pollution.

[0013]

The hardening coagulant for combustion ash according to the present invention comprises cement as a main component, lignin sulfonate as a dispersant and water reducing agent, and lime, gypsum and silicate as hardening accelerators. It can be obtained by mixing as an auxiliary agent and mixing them in harmony.

When the hardened coagulant thus obtained is added to an aggregate made of combustion ash such as fly ash which is spheroidized to eliminate stickiness, the hydration reaction between the aggregate and the cement and each auxiliary agent can be prevented. Various chemical reactions take place in parallel and interact with each other to deposit protruding products on the surface of the spheroidized combustion ash.

Then, the projection-like product generated on the surface of the combustion ash changes the surface of the combustion ash into a rough and sticky shape. As a result, the adhesiveness between the spherical aggregates can be increased, the amount of cement used can be reduced, and high hardness can be exhibited.

By mixing the above-mentioned hardened coagulant into various kinds of combustion ash and hardening and solidifying the mixture of the above-mentioned hardened coagulant and combustion ash, a minimum amount of cement is required to regenerate the combustion ash which is similar to waste. It is possible to obtain inexpensive building materials that are used. Therefore, the cost of building materials can be significantly reduced, and further, it will contribute to the treatment of combustion ash, which will become an increasingly social problem in the future.

[0017]

EXAMPLES An example of the hardening coagulant for combustion ash according to the present invention will be specifically described below. The hardening coagulant of combustion ash is for hardening and condensing various kinds of combustion ash and reusing the combustion ash as an aggregate of a building material, and promotes a main agent used as a hardening material and a hardening and setting reaction of the main agent. To form a high hardness.

As the main component, ordinary cement represented by hydraulic Portland cement is used. on the other hand,
As an auxiliary agent, a dispersion fluidizer, a water reducing agent, an adhesive agent, a lignin sulfonate such as sodium lignin sulfonate is used, and a hardening accelerator is lime such as slaked lime, gypsum, and aluminum silicate. Silicates are used.

More specifically, first, the cement used as the main component is made by using limestone and clay as main raw materials, finely crushing them and mixing them in harmony, followed by heating and cooling. Its composition is generally 3CaO ・ SiO ₂ /
_{50%, 2CaO · SiO 2/} 26%, 3CaO · Al 2 O 3/9%, 4CaO · Al 2 O 3 · Fe 2 O 3/9
%, And CaSO ₄ is also contained as standard.

Since many technical announcements have been made regarding the hardening reaction of cement, only the necessary items will be briefly described here. In other words, the hardening and setting of cement is caused by a number of hydration reactions that occur in parallel and interact with each other, resulting in subtle changes in the hydrate structure of each cement. It is carried out by a gel-like hydrate called cement gel which is formed by a rapid reaction.

In this hydration reaction, water diffuses inside through the gel-like film and a hydrate layer develops inside the film. This is a reaction generally called a topo chemical reaction, and the cement gel that has progressed and developed by this reaction gradually fills the voids between the aggregate particles and bridges each other while crystallizing to develop strength. It is known.

Next, each auxiliary will be described in detail. Lignin sulfonate, which is used as a dispersant / water reducing agent, is a product that is generally marketed as a water reducing agent for concrete and a soil conditioner, and is produced by treating the waste liquid discharged during pulp production. It is known as a raw material.

The lignin sulfonate is, for example, a sodium salt, a calcium salt or a magnesium salt of lignin sulfonic acid, and it is preferable to use the sodium salt. The reason is that even if a calcium salt is used, the reaction is similar, but since a large amount of lime, gypsum and calcium compounds described below are used, the white flower phenomenon is promoted unless careful attention is paid to the amount used. This is because it becomes a cause.

In this embodiment, a sodium salt, that is, sodium lignin sulfonate is used. The amount of such sodium lignin sulfonate used will be described later, but it should be set to the minimum required amount as much as possible. This is because there is a risk that sodium lignin sulfonate will be eluted from the finished product due to rainwater or the like after the cement is hardened, and voids will be generated in that portion, which will affect the product strength.

In addition, many adhesives such as CMC (carboxymethyl cellulose) and polyvinyl alcohol are known as adhesives, and they are commercially available, but they lack the dispersibility, fluidity and water-reducing property. Even when it is used as an adhesive, it is not chemically reactive, and there is a risk of elution with rainwater even after it is commercialized, which affects not only strength but also waterproofness.

Further, the purpose of using a curing accelerator as an auxiliary agent for the hardening coagulant is to reduce the amount of cement required to cure the aggregate, which is the combustion ash that has been spheroidized as before, and is economical. The problem is to solve the traditional problem of not being profitable. That is, in order to reduce the amount of cement used, it is necessary to enhance the adhesiveness between the spherical aggregates.

As a result of various experiments conducted by the inventor on this, the surface of the spheroidized combustion ash is changed into protrusions by adding appropriate amounts of lime, gypsum and silicate as hardening accelerators, as will be described later. Was successful. In the present embodiment, the lime, is used an inexpensive slaked lime, the gypsum, is used hemihydrate gypsum ^{_{(CaSO 4 · 1/2 H}} 2 O calcined gypsum), also the silicate, Aluminum silicate is used.

Next, the addition amounts of the main agent and each auxiliary agent to the aggregate which is the combustion ash will be specifically exemplified. 1) The addition amount of cement, which is the main ingredient, is 25% or less with respect to the aggregate that is combustion ash, and it is possible to achieve all the target strengths required for various building materials. It should be noted that the addition amount can be easily adjusted depending on the required strength of the product for each application.

2) Of the auxiliaries, the lignin sulfonate used as the dispersant / fluidizing agent and the water reducing agent is sodium lignin sulfonate in this example, and the addition amount is
An appropriate amount is 0.05 to 0.1% with respect to the cement. In addition,
If it is less than 0.05%, the viscosity will be insufficient, and if it is more than 0.1%, the action of delaying the curing will occur, and the productivity and workability will decrease during the production of the product.

3) Among the auxiliaries, lime used as one of the hardening accelerators is inexpensive slaked lime in this example, and the addition amount is 0.5% to 1.0% with respect to the aggregate. desirable. If 0.5% or less, insufficient reaction occurs, and if 1.0% or more is added, unreacted calcium content reacts with carbon dioxide gas in the air for a long time to cause a white flower phenomenon, which not only spoils aesthetics but also improves strength. It also causes a drop.

4) Among the auxiliaries, hemihydrate gypsum (CaSO ₄ .1 / 2H ₂ O calcined gypsum) is used as gypsum used as one of the hardening accelerators in the present embodiment, and the addition amount is as described above. 2% or less of SO ₃ relative to cement is sufficient. Any further addition results in retarding the setting of the cement. In addition, gypsum is also known to have effects such as short-term strength enhancement, drying shrinkage reduction, and chemical resistance enhancement.

5) As the silicate used as one of the curing accelerators among the auxiliaries, aluminum silicate is used in this embodiment, which may be a natural product or a synthetic product. The addition amount should be 20% or more and less than 30% with respect to the slaked lime. Addition of 30% or more is meaningless, on the contrary,
There is a risk of unreacted components remaining and causing strength deterioration.

Each of these added auxiliaries is hydrated or topo-reacted (Topo-chemical reaction) of the main ingredient, cement.
In addition to accelerating the growth of the ash, a crosslink is formed between the aggregates, which are combustion ash, to crystallize, and a strong strength is observed.

The action of the combustion ash and the hardened coagulant will be described below. When the curing accelerator according to the present invention is added to an aggregate composed of combustion ash such as fly ash that is spheroidized to eliminate stickiness, various chemistries such as a hydration reaction between the aggregate and cement, and each auxiliary agent The reactions occur in parallel.

The reaction of slaked lime added to the combustion ash includes ash and other additives such as cement, aluminum silicate,
When water is added to gypsum or the like and mixed and kneaded, it is important that weakly acidic components, that is, silicic acid components (SiO ₂ ) and alumina components (Al ₂ O ₃ ) are included. The silicic acid content and alumina content that have come into contact with slaked lime are eluted into the lime solution and react with lime to form calcium silicate hydrates (3CaO ・ SiO ₂・ nH ₂ O) and tobermorite (Ca ₅ (Si ₆ O ₁₈ H ₂ ) · 4H ₂ O) and calcium aluminate hydrate compounds _{(3CaO · Al 2 O 3 ·} nH 2 O, 4CaO · Al 2 O 3 · nH 2 O)
, Etc. to produce new reactants.

A part of the slaked lime reacts with the carbonic acid contained in the mixture to produce calcium carbonate (C
a (OH) + CO ₂ → CaCO ₃ + H ₂ O). Then, the generated calcium carbonate promotes densification and participates in a new reaction product, further reacts with calcium aluminates, and calcium aluminate carbonate hydrate (3CaO ・ Al
₂ O ₃ · CaCO ₃ · 12H ₂ O, 3CaO · Al ₂ O ₃ · 3CaCO ₃ · 32H ₂ O).

Further, a kalenite hydrate having both SiO ₂ and Al ₂ O ₃ (2CaO.Al ₂ O ₃ .SiO ₂ .nH ₂ O) is also formed and precipitated, and these are precipitated in the form of protrusions on the ash surface. with the reactants its growth, promote binding of the particles between each other to facilitate filling and densifying the voids between the particles, whereas, gypsum ^{_{(CaSO 4 · 1/2 H}} 2 O) is once dissolved in water And deposit as gypsum.

Hemihydrate gypsum near room temperature is crystalline gypsum (C
Solubility is significantly higher than that of aSO ₄・ 2H ₂ O). Therefore, when an appropriate amount of water is added to the hemihydrate gypsum and kneaded, the hemihydrate gypsum is rapidly dissolved and the needle-like crystals spread radially in a supersaturated state, and the gypsum crystals are precipitated all at once. As a result, the reaction of slaked lime is assisted and at the same time, protrusion-like precipitates are formed on the ash surface.

A large number of these produced precipitates change the surface shape of the combustion ash, and create appropriate voids between the ash to form a corpus. Then, the cement gel of a small amount of cement mixed in is gradually crosslinked while crystallizing so as to fill the voids, and it can be seen that the high strength required as a building material is exhibited.

As described above, if the hardened coagulant is mixed with the combustion ash and the mixture of the hardened coagulant and the combustion ash is hardened and solidified, the minimum amount of cement required will produce the combustion ash that is almost like waste. It is possible to obtain recycled building materials. Therefore, the cost of building materials can be significantly reduced, and further, it will contribute to the treatment of combustion ash, which will become an increasingly social problem in the future.

Finally, a composition example of a building material, which is a product manufactured by actually using the hardening coagulant according to the present example, using the Philippines Pinatubo ash and fly ash discharged from a thermal power plant as an aggregate, , An example of the product strength is shown.

1) Product name: Concrete block (standard strength 70.0kgf / cm ² ) Aggregate Volcanic ash 8,200.0gr Main agent Portland cement 1,900.0gr Auxiliary agent; Dispersion fluidizer / water reducing agent Sodium lignin sulfonate 1.5gr Auxiliary agent; Hardening accelerator Slaked lime 57.0 gr Hemihydrate gypsum 70.0 gr Aluminum silicate 14.5 gr 2) Product name: Concrete brick (standard strength 80.0 kgf / cm
² ) Aggregate Fly ash 2000.0gr Main agent Portland cement 400.0gr Auxiliary agent: Dispersion fluidizer / water reducing agent Sodium lignin sulfonate 0.3gr Auxiliary agent: Hardening accelerator Slaked lime 19.0gr Hemihydrate gypsum 20.0gr Aluminum silicate 5.3gr Mixing ratio above As a result of trial building of building materials at, the manifestation strength of volcanic ash exceeds the standard strength (70.0kgf / cm ² ) of 73.12k.
gf / cm ² and also for fly ash
The strength development of 100.9 kgf / cm ² exceeding (80.0 kgf / cm ² ) could be seen.

The building material produced by using the hardening coagulant of the present invention may be used in the same manner as in the conventional method for producing concrete products. In addition, based on the need for building materials, admixtures for cement products (AE agents, foaming agents,
A waterproofing agent) can be optionally added.

[0044]

According to the hardening coagulant for combustion ash according to the present invention, cement is used as the main agent, lignin sulfonate is used as a dispersant / water reducing agent, and lime, gypsum and silicate are used as hardening accelerators. Since each was composed as an auxiliary agent, the surface of combustion ash such as fly ash that is spherical and non-sticky to be used as an aggregate can be changed into a bumpy uneven shape with a minimum amount of cement required. By using it, it is possible to harden and solidify the combustion ash as a waste and reuse it as a building material, and it is possible to significantly reduce the manufacturing cost of such building material.

Further, according to the method for manufacturing a building material of the present invention, high hardness can be exhibited by using the hardening coagulant, and various conditions required for each building material can be obtained at low cost. It is possible to meet the demand of building materials. In addition, it will also contribute to the treatment of combustion ash, which will become an increasingly social problem in the future.

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Claims (3)

[Claims] 1. A hardening coagulant of combustion ash for hardening and condensing various kinds of combustion ash and reusing the combustion ash as an aggregate of a building material, which comprises cement as a main agent and a dispersing fluidizer / water reducing agent. And a lignin sulfonate as a hardening accelerator, and lime, gypsum, and silicate as a hardening accelerator, respectively, as an auxiliary agent to be mixed in harmony with the main agent, and a hardening coagulant for combustion ash. 2. The curing coagulant for combustion ash according to claim 1, wherein aluminum silicate is used as a silicate which is one of the curing accelerators constituting the auxiliary agent. 3. A method for producing a building material, which comprises mixing the hardening coagulant for combustion ash according to claim 1 into combustion ash and hardening and solidifying a mixture of the hardening coagulant and the combustion ash.