KR102086017B1 - Artificial Aggregate using Fly Ash, and Manufacturing Method thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing artificial fine aggregate, and artificial fine aggregate manufactured thereby. In the manufacturing method, fly ash generated in a fluidized bed boiler power plant is used, wherein the fly ash contains 5-15 wt% of free calcium oxide based on 100 wt% of the fly ash, and in a process of making fly ash spherical, the fly ash is sprayed with an aqueous phosphoric acid solution, wherein the fly ash is granulated by being sprayed with the aqueous phosphoric acid solution containing 0.05 to 0.5 M (molality) of phosphoric acid (H_3PO_4).

Description

Artificial Aggregate with Reduced Absorption Rate and its Manufacturing Method {Artificial Aggregate using Fly Ash, and Manufacturing Method}

The present invention relates to an artificial fine aggregate using a fly ash and a method for manufacturing the same, and specifically, to produce an artificial fine aggregate using fly ash generated as waste in a thermal power plant using a circulating fluidized bed boiler. In the process of forming into a sphere and granulating, the absorption rate of artificial fine aggregate produced by spraying fly ash using phosphate solution as a globule solution is reduced. A method for producing an absorbency-reduced artificial fine aggregate, which enables the formation of aggregates efficiently by using a bed material of a fluidized bed boiler as a core or a seed of a globular process, and artificial Fine aggregate ".

Incineration ash generated by incineration of fuel in thermal power plants, that is, attempts to artificially produce aggregates using ash is made through Korean Patent No. 10-0241564. However, since artificial fine aggregate manufactured by the prior art has a very high absorption rate and low density, there is a big limitation in using it in concrete or mortar which needs to manage the strength according to the amount of water used. There is an inactive problem. In particular, when using artificial fine aggregates of the prior art, such as structural concrete or mortar requiring fine control of strength, there is a problem that the artificial fine aggregates agglomerate with each other, and the advantages that can be expected by using artificial fine aggregates, The disadvantage is that there are few advantages in terms of waste recycling and cost reduction. As an alternative to this, strong alkali materials such as water glass may be used, but in this case, durability problems such as bleaching are caused, and an attempt to reduce water absorption by additionally applying organic coating or water repellent coating to artificial fine aggregate prepared by the prior art. However, in this case, there is a problem in that an excessive cost is required for coating and economic efficiency is lowered.

Republic of Korea Patent Publication No. 10-0241564 (2000. 02. 01. notification).

The present invention was developed to overcome the above limitations of the prior art, by using an ash generated in a thermal power plant, in particular a fly ash generated in a power plant using a circulating fluidized bed boiler ("circulating fluidized bed boiler power plant"). By producing artificial fine aggregate, by improving the process performed to improve the physical properties of artificial fine aggregate, by reducing the absorption rate of artificial fine aggregate, it is possible to proceed more efficiently the production process of artificial fine aggregate while greatly improving the performance as aggregate The purpose is to provide the technology.

In order to achieve the above object, in the present invention, as a method for manufacturing artificial fine aggregate using fly ash, using fly ash generated in a fluidized bed boiler power plant, 5 to 15% by weight of free calcium oxide at 100% by weight fly ash Using fly ash contained as; Spray the phosphate solution in the fly ash in the fly ash process of fly ash, granulate the fly ash by spraying the phosphate solution containing phosphoric acid (H ₃ PO ₄ ) 0.05 to 0.5M (molal concentration) Provided is a method for producing artificial fine aggregate, characterized in that the making.

In addition, in the present invention, in order to achieve the above object, to be manufactured by using a fly ash generated in a fluidized bed boiler power plant, fly ash, which contains 5 to 15% by weight of free calcium oxide in 100% by weight fly ash. ; An artificial fine aggregate is formed by granulating the phosphate solution having a phosphoric acid concentration of 0.05 to 0.5 M (molal concentration) in the fly ash process by spraying and stirring the fly ash as a globule solution.

In the manufacturing method of the present invention and the artificial fine aggregate made by the above, in the fly ash process, the core of the granular material having a size of up to 0.5 mm or less in diameter is further added to the fly ash and phosphate aqueous solution By stirring with, the fly ash and the phosphate solution is mixed while being attached to the outside of the core to form an artificial fine aggregate, the core may be contained in 2.5 to 7.5 parts by weight based on 100 parts by weight of the fly ash.

Furthermore, in the above-described manufacturing method of the present invention and the artificial fine aggregate produced thereby, the fly ash used for the production of the artificial fine aggregate is a fly ash generated in a circulating fluidized bed boiler power plant, and the free calcium oxide is contained at 100% by weight of the fly ash. It may be contained in 5 to 10% by weight, in particular, the phosphoric acid concentration of the aqueous solution of phosphate sprayed fly ash in the composition process for artificial fine aggregates may be 0.25 to 0.5M (molal concentration).

According to the present invention, having a low absorption rate, it is possible to make artificial fine aggregate which can be very usefully used for concrete or mortar at low cost.

FIG. 1 is a photograph substituted for drawing micrographs of a state of stirring with fly ash using simple water containing no phosphoric acid as a glotular solution.
FIG. 2 is a photograph substituted for the microscopic view of the surface of artificial fine aggregate made of water containing 2.5% by weight of free calcium oxide and not containing phosphoric acid as a glotular solution.
FIG. 3 is a photograph substituted for the microscopic view of the surface of an artificial fine aggregate containing 5% by weight of free calcium oxide and made of a phosphoric acid solution having a phosphoric acid concentration of 0.25 M as a glotular solution.
Figure 4 is a schematic conceptual diagram of another embodiment of the present invention for producing artificial fine aggregate by performing the seongseonggu process using the core.
FIG. 5 is a photograph substituted for the micrograph of the shape of the artificial fine aggregate manufactured by performing the composition process without using the core. FIG.
FIG. 6 is a photograph substituted for a microscopic view of a shape of an artificial fine aggregate prepared by adding 2.5 parts by weight of a bed material of a fluidized bed boiler as a core based on 100 parts by weight of a fly ash.
FIG. 7 is a photograph substituted for a microscopic view of a molding shape of artificial fine aggregate prepared by adding 5.0 parts by weight of a bed material of a fluidized bed boiler as a core relative to 100 parts by weight of fly ash.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is described as one embodiment, whereby the technical spirit of the present invention and its core configuration and operation are not limited.

In the present invention, artificial fine aggregate is manufactured using fly ash generated in a fluidized bed boiler power plant. In particular, the fly ash used to prepare the artificial fine aggregate according to the present invention, which occurs in a circulating fluidized bed boiler power plant, contains 5-15 wt% of free calcium oxide (free-CaO) in 100 wt% of fly ash. It is limited. In the case of fly ash containing less than 5% by weight of free calcium oxide, the amount of free calcium oxide to react with the phosphate solution introduced during the production of artificial fine aggregates will be insufficient, thereby adding free calcium oxide. The expression of the effect of reducing water absorption is minimal. On the other hand, if the free calcium oxide exceeds 15% by weight based on 100% by weight of the fly ash, the amount of free calcium oxide becomes excessively high, thereby increasing the amount of aqueous solution of phosphate required for the reaction, and excess unreacted glass. Due to calcium oxide, when used in concrete or mortar as artificial fine aggregate, it is not suitable because it leads to expansion failure. Therefore, the fly ash used in the present invention is generated in a fluidized bed boiler power plant containing 5 to 15% by weight of free calcium oxide (when the total weight of the fly ash is 100, the weight of free calcium oxide in the fly ash is 5 to 15) It is limited to what is. The most preferred of the fly ash used in the present invention is generated in a circulating fluidized bed boiler power plant, which contains 5 to 10% by weight of free calcium oxide in 100% by weight of the fly ash.

In the manufacturing method of artificial fine aggregate according to the present invention, while using the fly ash generated in the fluidized bed boiler power plant having the above free calcium oxide content, the aqueous solution of phosphate in the globular process to granulate the fly ash into a sphere (sphere) By spraying the fly ash as a globule solution, the finally produced artificial fine aggregate has a reduced absorption rate. Specifically, in the present invention, the phosphate solution is sprayed on the fly ash in the fly ash process. The phosphate solution used at this time contains phosphoric acid (H ₃ PO ₄ ) in a concentration of 0.05 to 0.5M (molal concentration). In the composition process for granulating fly ash when producing artificial fine aggregate according to the present invention, the fly ash of the fluidized bed boiler power plant containing free calcium oxide (Free-CaO), the phosphoric acid aqueous solution having the above-mentioned phosphoric acid concentration When sprayed, the free calcium oxide in fly ash is instantaneously hydrated to form calcium hydroxide (Ca (OH) ₂ ) according to Formula 1 below to combine to form granular globules. At this time, the chemical reaction represented by the formula (2) and formula (3) also proceeds.

[Formula 1]

CaO + H ₂ O => Ca (OH) ₂

[Formula 2]

^{_{H 3 PO 4 => H +}} + PO 4 -

[Formula 3]

_{Ca (OH) 2 + PO 4} - ==> calcium phosphate hydrate _{(CaHPO 4 or CaHPO 4 2H 2} O 2.)

Calcium phosphate-based hydrate is produced by the reaction of calcium hydroxide with phosphoric acid. Calcium phosphate-based hydrate densely fills the pores of the porous artificial fine aggregate, thereby lowering the surface absorption rate, thereby reducing the absorption rate of the artificial fine aggregate.

In the preparation of artificial fine aggregate, the use of phosphate solution with phosphoric acid concentration less than 0.05M (molal concentration) has little effect of reducing the absorption rate of artificial fine aggregate, whereas phosphoric acid with phosphoric acid concentration exceeding 0.5M (molal concentration) The use of an aqueous solution is not only economically inferior, but may also cause problems such as delay in hydration of cement when used in concrete or mortar due to residual phosphoric acid after the reaction. Therefore, in the present invention, the aqueous solution of phosphate to be sprayed in the fly ash process of the fly ash is preferably a phosphoric acid concentration of 0.05 to 0.5M (molal concentration), more preferably a phosphoric acid concentration of 0.25 to 0.5M (molal concentration).

Next, examples and comparative examples according to the present invention will be described.

Examples and comparative examples according to the present invention were manufactured using five kinds of fly ash discharged from Samcheok Green Power Power Plant (corresponding to a circulating fluidized bed boiler type power plant), respectively, and the content of free calcium oxide is 100 wt. 0% by weight (without free calcium oxide), 2.5% by weight, 5.0% by weight, 7.5% by weight and 10% by weight relative to% were used. The sprayed aqueous solution of phosphoric acid used a phosphoric acid concentration of 0M (molar concentration) (without phosphoric acid), 0.25M, 0.5M, 0.75M and 1.0M, respectively, and the pH of the water used in the aqueous solution of phosphoric acid was 6.8.

As a method for forming artificial fine aggregate, fly ash (1,600 kg) is placed in the composition and sprayed about 250 to 420 kg of a globule solution (water or aqueous phosphate solution) to reach the required particle size as artificial fine aggregate, followed by stirring for 3 minutes and drying. Was used.

Examples and comparative examples of the present invention as described above are summarized in Table 1 below. In Table 1 below, <Experiment 1> is the content of free calcium oxide (Free-CaO) is 0% by weight based on 100% by weight of fly ash, <Experiment 2> is 100% by weight of fly ash content of free calcium It is 2.5% by weight relative to the "comparative example", respectively, <Experiment 3> to <Experiment 5> is the content of free calcium oxide (Free-CaO) is 5.0% by weight relative to 100% by weight of fly ash, respectively Thing (experiment 3), 7.5 weight% (experiment 4), and 10.0 weight% (experiment 5) correspond to the "example" of this invention. Absorption rate and the pH of the aqueous solution in which the artificial fine aggregate was added were respectively measured for the artificial fine aggregate prepared in Examples and Comparative Examples of the present invention. The measured absorption rate and pH of the aqueous solution are summarized together in Table 1.

It is preferable that the absorption rate of the artificial fine aggregate molded into granules is low, and the pH of the aqueous solution in which the artificial fine aggregate is added is preferably in the range of 6.5 to 9.0 with little change. Therefore, in Table 1 below, the absorption rate of artificial fine aggregates in Experiments 1 to 5 was less than 10%, and the pH range of the aqueous solution was 6.5 to 8.5.

As summarized in Table 1 above, the artificial fine aggregate according to the embodiment of the present invention is much higher than the comparative example of <Experiment 1> manufactured using a fly ash containing no free calcium oxide (Free-CaO). It shows a low absorption rate, the pH of the aqueous solution containing artificial fine aggregate was also found to be within the desired optimum range. In particular, the artificial fine aggregate according to the embodiment of the present invention made by using a free calcium oxide content of 5 to 10% by weight relative to 100% by weight of fly ash and a phosphoric acid concentration of 0.25 to 0.5M (molal concentration) Has been found to have an optimal absorption and pH range.

FIG. 1 is a diagram showing the microscopic image of a fly ash and agitation state using simple water (phosphate concentration 0M) as a lyric acid solution. As shown in FIG. 1, simple water without phosphoric acid is shown. In the case of using as a globular solution, a large number of cracks are present on the surface, thereby greatly increasing the water absorption.

FIG. 2 is a microscopic view of the surface of artificial fine aggregate, which is made of simple water (phosphate concentration 0M) containing no phosphoric acid as a glotular solution, but containing 2.5% by weight of free calcium oxide, based on 100% by weight of fly ash. FIG. 3 is a micrograph of the surface of artificial fine aggregates containing 5% by weight of free calcium oxide in an amount of 5% by weight based on 100% by weight of fly ash and using a phosphoric acid solution having a phosphoric acid concentration of 0.25 M (molar concentration) as a globular solution. It is a photograph substitute drawing. As can be seen from FIG. 3, when the free calcium oxide content in the fly ash falls within the range proposed by the present invention as 5% by weight, and the phosphate concentration of the aqueous phosphate solution used as the globule solution is 0.25M (molal concentration), When the film is formed on the surface of the artificial fine aggregate, the effect of reducing water absorption can be confirmed.

In the present invention described above, and the above Experiment 1 to Experiment 5, artificial fine aggregate was prepared by spraying and stirring the globule solution in fly ash. However, if necessary, cores or seeds may be used in the scripting process. Figure 4 is a schematic conceptual diagram of another embodiment of the present invention for producing artificial fine aggregate by performing a seongseonggu process using the core. In the present invention, as another embodiment of manufacturing artificial fine aggregate using only the fly ash and the globules solution described above, as shown in Figure 4, by further adding a core (core) to the globules in the penis process, stirring, The fly ash and the globular solution (phosphate solution) are mixed to the outside of the core to make a spherical artificial fine aggregate. Bed material (eg bottom ash) of a fluidized bed boiler can be used as the core of the lumbering process. At this time, the core is a granular material having a size of 0.5 mm or less in the maximum particle size, and is contained 2.5 to 7.5 parts by weight based on 100 parts by weight of the fly ash. For example, if 100 kg of fly ash is used, the core of the granular material is 2.5 to 7.5 kg.

As described above, in order to verify another embodiment of the present invention for preparing artificial fine aggregate by performing the vocal fold process, the following <Experiment 6> to <Experiment 10> were performed.

Specifically, for those determined as the optimal blend among Experiments 1 to 5, which produced artificial fine aggregates using only fly ash and globules solution, in addition to using the free calcium oxide and the phosphate solution of the corresponding phosphoric acid concentration The artificial fine aggregates of <Experiment 6> to <Experiment 10> were prepared by adding a bed material of a fluidized bed boiler having a particle diameter of 0.5 mm or less and adding them as cores at different contents to perform a globule process. The density of the bed material used as the core in the fabrication of Experiments 6 to 10 was 2.6 to 2.8 g / cm ³ , and the bottom ash generated in the same mild fluidized bed boiler process was obtained by sieving. .

The more the fine powder is, the less smooth the molding is, and the result is less rigid, so that the absorption rate can be increased. Therefore, it is important to measure the amount of fine powder to determine the molding efficiency of the aggregate. Therefore, the artificial fine aggregates of Experiments 6 to 10 were prepared by performing the composition process by adding different contents (mass parts) of the core composed of bed materials to 100 parts by weight of fly ash for the optimum mixture selected in Table 1. The amount of fine passage of less than 0.08 mm in particle size for each artificial fine aggregate produced was measured.

<Experiment 6> is the content of the core is 0 parts by weight based on 100 parts by weight of fly ash, <Experiment 7> is the content of the core is 2.5 parts by weight based on 100 parts by weight of fly ash, and <Experiment 8> is 100 parts by fly ash 100 Content of a core is 5.0 weight part with respect to a weight part. <Experiment 9> is content of a core of 7.5 weight part with respect to 100 weight part of fly ash, and <Experiment 10> is content of 10.0 weight part with respect to 100 weight part of fly ash. In this manner, the artificial fine aggregates of <Experiment 6> to <Experiment 10> are made by adding a core to the selected optimal mixture among <Experiment 1> to <Experiment 5> in Table 1, and to each artificial fine aggregate The amount of passage through the sieve of 0.08 mm scale was measured. Details of <Experiment 6> to <Experiment 10> and the measurement results thereof are summarized in Table 2. In Table 2, each numerical value of <0.08mm sieve passing amount> shows the weight ratio of the fine powder which passed the 0.08mm sieve with respect to the weight of the artificial fine aggregate finally shape | molded.

As summarized in Table 2 above, when the content of the core is 5 parts by weight, the amount of passage of 0.08 mm is the lowest, and when the content of the core is 2.5 to 7.5 parts by weight, the amount of passage of 0.08 mm is in the proper range. In preparing the artificial fine aggregate, it was confirmed that the content of the core is preferably 2.5 to 7.5 parts by weight based on 100 parts by weight of the fly ash.

FIG. 5 is a photograph substituted for a microscopic view of a shape of an artificial fine aggregate prepared by performing a globule process without using a core, and FIGS. 6 and 7 respectively show a bed material of a fluidized bed boiler as a core. Figure 6 is a drawing substitute photomicrograph of the shape of the artificial fine aggregate prepared by adding, in the case of Figure 6 the content of the core is 2.5 parts by weight with respect to 100 parts by weight of the fly ash, in the case of Figure 7 The content of the core is 5.0 parts by weight. As can be seen in Figures 5 to 7, when the seonggyeong process using the core in the content range proposed in the present invention, seonggu as a spherical artificial fine aggregate proceeds very efficiently.

According to the manufacturing method of the present invention described above, it is possible to greatly reduce the absorption rate for the artificial fine aggregate made by using the fly ash.

Claims (8)

Using fly ash generated in a fluidized bed boiler power plant, using fly ash containing 5 to 15% by weight of free calcium oxide at 100% by weight of the fly ash;
In the fly ash process, a phosphoric acid solution having a phosphoric acid concentration of 0.05 to 0.5 M (molar concentration) is granulated by spraying and stirring with fly ash as a globule solution to produce fine aggregates;
In the process of the process of fly ash, an additional core made of granular material having a maximum particle size of 0.5 mm or less is added and stirred with the fly ash and the phosphate solution. Is formed;
The core is a method for producing artificial fine aggregate, characterized in that contained in 2.5 to 7.5 parts by weight based on 100 parts by weight of fly ash.
delete The method of claim 1,
Fly ash is a fly ash generated in a circulating fluidized bed boiler power plant;
A method for producing artificial fine aggregate, characterized in that the free calcium oxide is contained in 5 to 10% by weight relative to 100% by weight of fly ash.
The method of claim 1,
The phosphoric acid concentration of the aqueous solution of phosphoric acid is 0.25 to 0.5M (molal concentration) method for producing artificial fine aggregate.
Manufactured using fly ash from a fluidized bed boiler power plant,
Fly ash contains 5 to 15% by weight of free calcium oxide in 100% by weight of the fly ash;
In the fly ash process, a phosphoric acid solution having a phosphoric acid concentration of 0.05 to 0.5 M (molal concentration) is granulated by spraying and stirring the fly ash as a globule solution;
In the process of the process of fly ash, an additional core made of granular material having a maximum particle size of 0.5 mm or less is added and stirred with the fly ash and the phosphate solution. Is formed,
Core is artificial fine aggregate, characterized in that contained in 2.5 to 7.5 parts by weight based on 100 parts by weight of fly ash.
delete The method of claim 5,
Fly ash is a fly ash generated in a circulating fluidized bed boiler power plant;
Artificial fine aggregate, characterized in that the free calcium oxide is contained in 5 to 10% by weight of fly ash 100% by weight.
The method of claim 5,
Phosphoric acid concentration of the aqueous solution of phosphate is artificial fine aggregate, characterized in that 0.25 to 0.5M (molal concentration).

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