KR20150035653A - Additive for concrete comprising bottom ash and the method for preparing thereof - Google Patents

Abstract

The present invention relates to a concrete admixture using bottom ash; and to a manufacturing method of the admixture. According to an embodiment of the present invention, provided is a concrete admixture using bottom ash, which comprises a pulverized form of bottom ash generated by rapidly cooling a coal material in a synthetic natural gas (SNG) manufacturing process. According to another embodiment of the present invention, provided is a manufacturing method of a concrete admixture using bottom ash, which comprises the steps of collecting bottom ash generated in an SNG manufacturing process; and pulverizing the collected bottom ash. The present invention pulverizes bottom ash generated in an SNG manufacturing process and uses the bottom ash for a concrete admixture, thereby allowing economic efficiency to be enhanced by recycling the bottom ash that is a by-product. In addition, the amount of cement used is reduced in a concrete manufacturing process by using the admixture. Accordingly, the present invention can prevent environmental pollution caused by carbon dioxide generated in a conventional cement manufacturing process and an alkaline component dissolved from cement.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an additive for a concrete using a bottom ash,

The present invention relates to an admixture for concrete using a bottom ash and a method of manufacturing the same, and more particularly, to a method of manufacturing an admixture for concrete by collecting bottom ash generated in the process of producing synthetic natural gas (SNG) And how to use it.

The syngas obtained through the gasification of coal contains carbon monoxide (CO) and hydrogen (H ₂ ) gas as its main components and can be used as a fuel to generate electricity or to produce various raw materials through appropriate purification, separation and synthesis processes. .

This clean coal technology is considered to be one of the realistic ways to prepare for high oil prices and depletion of petroleum resources, which have attracted much attention in recent energy fields.

In other words, one of the various methods of using coal as an energy source to replace petroleum and natural gas is the production of synthetic natural gas (SNG) using synthetic gas generated through gasification reaction, A solid sample is used to produce methane-based fuel gas.

On the other hand, the method of producing synthetic natural gas using coal is mainly based on a method based on gasification of coal using well-known oxygen and steam. At this time, about 10% of the coal raw material is used as bottom ash ash.

Bottom ash, which is a by-product after combustion of coal raw material, is generated by rapid cooling at high temperature. It is present as a liquid phase at high temperature and then solidified by rapid cooling. As a result, the bottom ash is irregularly shaped .

In addition, the silica (SiO ₂ ) contained in the coal raw material is generated in a large amount by glass quality of a bed having a particle size of 1 to 10 cm by rapid cooling, and is mixed into the bottom ash, and it is difficult to use silica as a road or concrete aggregate.

In this regard, FIG. 1 shows photographs of the bottom ash produced in the synthetic natural gas production process by particle size, and FIGS. 1 (a) to 1 (c) It can be seen that glassy bed is mixed.

FIG. 2 is a graph showing X-ray diffraction analysis (XRD) results of bottom ash produced in a synthetic natural gas production process. In the graph of FIG. 2, Are typical amorphous phases mixed with various types of dyes.

The present invention can be utilized as an admixture for concrete by powdering the bottom ash generated in the process of Synthetic Natural Gas (SNG), and selectively mixing calcium hydroxide (Ca (OH) ₂ ) So that the strength of the concrete can be further improved by incorporating the desulfurization slag generated in the treatment process.

According to an embodiment of the present invention, there is provided an admixture for concrete using a bottom ash containing a powder of bottom ash generated by rapid cooling of a coal raw material in a process of producing synthetic natural gas (SNG).

The bottom ash is silicon dioxide (SiO ₂₎ 40 to 50% by weight, aluminum oxide (Al ₂ O ₃₎ 20 to 30% by weight, calcium (CaO) 7 to 12% and iron oxide by weight of oxide based on the total weight of (Fe ₂ O ₃ ) 5 to 10% by weight.

The bottom ash may be generated by rapidly cooling the coal raw material at a cooling rate of 300 ° C / sec or more.

The bottom ash powder may have a maximum particle size of 75 mu m or less.

According to another embodiment of the present invention, there is provided a binder for concrete comprising the admixture for concrete.

The admixture for concrete may be contained in an amount of 5 to 25% by weight based on the total weight of the binder for concrete.

The binder for concrete may further include a calcium hydroxide (Ca (OH) ₂ ) or a desulfurized slag fine powder having a powderity of 3000 cm ² / g or more generated in the preliminary treatment of molten iron.

The calcium hydroxide (Ca (OH) ₂ ) or the desulfurized slag fine powder may be contained in an amount of 3 to 8% by weight based on the total weight of the binder for concrete.

According to another embodiment of the present invention, there is provided a process for the production of synthetic natural gas (SNG) comprising: recovering bottom ash generated in a process for producing synthetic natural gas (SNG); And

And crushing the recovered bottom ash. The present invention also provides a method of manufacturing an admixture for concrete using the bottom ash.

The bottom ash pulverized in the pulverizing step may have a maximum particle size of 75 mu m or less.

Subsequent to the pulverizing step, the step of collecting 45 to 55% from the top of the ash floated through the air classification of the pulverized bottom ash may be further included.

The bottom ash collected in the collecting step may have a maximum particle size of 45 mu m or less.

The bottom ash generated in the process of producing synthetic natural gas (SNG) is powdered and used as an admixture for concrete, thereby improving the economical efficiency by recycling the by-product, bottom ash. The use of the admixture reduces the amount of cement used in the production of concrete, thereby achieving an economical effect. It also prevents environmental pollution caused by carbon dioxide generated in the conventional cement production and alkaline components eluted from the cement.

FIG. 1 is a photograph showing the bottom ash produced in the synthetic natural gas production process according to particle size.
FIG. 2 is a graph showing the results of X-ray diffraction analysis (XRD) of bottom ash produced in the synthesis natural gas production process.
FIG. 3 is a graph showing the results of measuring the compressive strengths of the test specimens measured in Experimental Examples 1 to 12 at 3, 7, and 28 days according to the KS standard.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

According to one embodiment of the present invention, there is provided an admixture for concrete using a bottom ash and a method of manufacturing the same. In the present invention, when bottom ash generated during the process of producing synthetic natural gas (SNG) is used as an admixture for concrete, The admixture is cured with the hydration reaction product generated by the hydration reaction between the cement and water, causing a secondary reaction, which helps to improve the strength of the concrete in the long term and reduces the amount of cement used. You can help.

With regard to the bottom ash used as a concrete admixture for concrete in the present invention, about 10% of the coal raw material introduced during the synthesis natural gas production process is generated as bottom ash, and the by- The bottom ash is present in a liquid state at a high temperature, and is rapidly transformed into a solid phase by rapid cooling with water or air and is discharged. However, the bottom ash discharged at this time contains a large amount of glassy material by the rapid cooling, and besides, it is mixed with materials having various particle sizes and irregular shape, which is not suitable for application to concrete admixture.

Accordingly, in the present invention, in order to produce the admixture for concrete, it is preferable to perform the step of recovering the discharged bottom ash and obtaining the bottom ash powder by pulverizing the bottom ash so as to be suitable for the admixture for concrete.

Meanwhile, the bottom ash used in the concrete admixture for concrete includes 40 to 50% by weight of silicon dioxide (SiO ₂ ), 20 to 30% by weight of aluminum oxide (Al ₂ O ₃ ), calcium oxide (CaO) 7 to 12% by weight and iron oxide (Fe ₂ O ₃₎ preferably comprises 5-10% by weight.

In addition, the bottom ash is formed by rapid cooling at a cooling rate of 300 ° C / sec or more at a cooling rate of at least 300 ° C / sec, and the amorphous content of the bottom ash is as high as 95% or more and is suitable for the expression of the compressive strength of the concrete when used as an admixture for concrete . That is, when the cooling rate is 300 ° C / sec or more, the amorphous content of the bottom ash becomes 95% or more and the compression strength of the concrete is excellent. However, when the cooling rate is less than 300 ° C / sec, For example, when the cooling rate is 290 ° C / sec, amorphous is 77% and crystalline is 23%. When the cooling rate is 280 ° C / sec, amorphous is 32% and crystalline is 68% There may be a problem that it is difficult to manifest a predetermined compressive strength due to a decrease in the content.

The higher the cooling rate, the better the amorphous content. In particular, when the cooling rate is 350 [deg.] C / sec, the amorphous content is 99% desirable. However, when the cooling rate is higher than 350 ° C / sec, it is costly to reach the same speed, and since the effect of improving the compressive strength of the concrete against cost is insignificant, the cooling rate in the present invention is 300 to 350 ° C / sec is most preferable.

In order to utilize the bottom ash as an admixture for concrete as described above, the bottom ash is preferably pulverized and pulverized. Although the pulverization method is not particularly limited, a conventional pulverization method using a ball mill or the like can be used have.

The bottom ash powder obtained by the pulverization preferably has a maximum particle size of 75 탆 or less, which is about the average particle size of the cement powder, more preferably 45 탆 or less, and the lower limit is not particularly limited. The smaller the particle size, . However, when the particle size exceeds 75 탆, the curing reaction rate of the concrete may become slow and the strength development may also be slow.

Further, in the present invention, as described above, the powder of the bottom ash having a particle size of 45 탆 or less is more preferable for improving the compressive strength of the concrete and improving the speed of the concrete curing reaction.

Thus, the bottom ash powder having a maximum particle size of 45 μm or less can be obtained by grinding the bottom ash until the particle size falls within the above range, or after grinding, the particle size is 45 μm or less using air separation .

At this time, the classification method is not particularly limited, but the bottom ash powder ground to a maximum particle size of 75 탆 or less is collected by 45 to 55% from the top of the ash floated by using an air classifier , And the bottom ash powder having a maximum particle size of 45 탆 or less can be granulated.

According to another embodiment of the present invention, there is provided a binder for concrete comprising the admixture for concrete.

The admixture for concrete contained in the binder for concrete is preferably contained in an amount of 5 to 25% by weight based on the total weight of the binder, and the remainder generally includes cement as a main component of the binder.

When the content of the admixture is less than 5% by weight, the amount of the admixture replacing cement is extremely small, which is difficult to achieve the economic effect of the present invention. On the other hand, when the content exceeds 25% by weight, The strength of concrete was lowered at the time of curing in the future because of the relatively insufficient amount of hydration reactant between cement and water compared to the admixture. The strength of concrete was measured to be lower than 42.5 MPa .

In the present invention, the binder for concrete may further include calcium hydroxide (Ca (OH) ₂ ) in addition to bottom ash powder. The bottom ash shows an amorphous phase as shown in FIG. 2. When calcium hydroxide is mixed therein, the hydroxyl group (OH ^- ) contained in the calcium hydroxide stimulates the vitreous coating of the amorphous bottom ash, that contains Ca ^{2 +,} Al ^{3 +,} and Si ^{+ 2} ion elution rate of such is becomes faster, CaO-SiO ₂ -H ₂ O and _{CaO-Al 2 O 3 -H 2} O to promote the formation of compound Therefore, it can further contribute to the improvement of the strength of the concrete.

The present invention may include, in addition to calcium hydroxide, the binder in place of a desulfurization slag mainly composed of calcium hydroxide as a by-product generated in a molten iron pre-treatment process. At this time, the desulfurization slag is self-differentiated and may be in the form of a fine powder. The degree of the powder is preferably 3000 cm ² / g or more, which is similar to that of cement, and the upper limit is not particularly limited.

In the present invention, the calcium hydroxide or the desulfurized slag fine powder contained in the binder is preferably contained in an amount of 3 to 8% by weight based on the total weight of the binder. When the content is less than 3% by weight, the effect of stimulating the glassy coating of the bottom ash is insignificant and consequently the effect of improving the strength of the concrete is insignificant. When the content exceeds 8% by weight, the effect of improving the initial strength is insignificant , There may be a problem of causing a sudden decrease in fluidity of the cement.

Example

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

[Example 1]

In the production process of synthetic natural gas (SNG), the coal ash was generated by quenching the coal fuel at a cooling rate of 300 ° C / sec by using water. The bottom ash having the composition shown in Table 1 was mixed with a ball mill And crushed. In addition, 50% of the pulverized bottom ash powder was collected from the upper portion through air classification to obtain a bottom ash powder having a maximum particle size of 45 탆 or less. The prepared bottom ash powder and cement and the desulfurized slag fine powder having a degree of powder of 3000 cm ² / g or more generated as a by-product in the iron wire pretreatment process in the steel process were mixed in the amounts shown in Table 2 to prepare a total of 1350 g of binder for concrete And Table 3 below shows conversion of the content of each component contained in the binder in terms of weight% in Table 2.

[Comparative Example 1]

Unlike the above-mentioned examples, instead of bottom ash, 1350 g of a binder for concrete was prepared by mixing fly ash produced in a thermal power plant, which was conventionally used as a concrete admixture for concrete, with cement in the amounts shown in Table 2 below. Is the conversion of the content of each component contained in the binder to weight% in Table 2.

SiO ₂ Al ₂ O ₃ CaO Fe ₂ O ₃ SO ₃ Cl C Bottom ash composition
(weight%) 45.0 24.1 10.6 7.97 0.11 0.0002 1.13

division Binder composition (g) SNG Bottom ash powder Desulfurization slag
Fine powder Thermal power generation
Fly ash cement Maximum particle size
75 μm or less Maximum particle size
45 μm or less Example 1 67.5 - - - 1282.5 Example 2 202.5 - - - 1147.5 Example 3 - 202.5 - - 1147.5 Example 4 202.5 - 54 - 1093.5 Example 5 - 202.5 54 - 1093.5 Example 6 202.5 - 81 - 1066.5 Example 7 202.5 - 108 - 1039.5 Comparative Example 1 - - - 67.5 1282.5 Comparative Example 2 - - - 202.5 1147.5 Comparative Example 3 202.5 - 27 - 1120.5 Comparative Example 4 202.5 - 135 - 1012.5 Comparative Example 5 - - - - 1350

division Binder composition (% by weight) SNG Bottom ash powder Desulfurization slag
Fine powder Thermal power generation
Fly ash cement Maximum particle size
75 μm or less Maximum particle size
45 μm or less Example 1 5 - - - 95 Example 2 15 - - - 85 Example 3 - 15 - - 85 Example 4 15 - 4 - 81 Example 5 - 15 4 - 81 Example 6 15 - 6 - 79 Example 7 15 - 8 - 77 Comparative Example 1 - - - 5 95 Comparative Example 2 - - - 15 85 Comparative Example 3 15 - 2 - 83 Comparative Example 4 15 - 10 - 75 Comparative Example 5 - - - - 100

[Experimental Example 1]

675 g of water and 4050 g of ISO standard yarn were blended into the binders prepared in Examples 1 to 7 and Comparative Examples 1 to 5 and then a rectangular test piece of 4 x 4 x 16 cm having a total weight of 6075 g was prepared and the " (KS L ISO 679), the compressive strengths were measured on days 3, 7, and 28, and the results are shown graphically in FIG.

According to Fig. 3, when the bottom ash and the fly ash were replaced by cement in an amount of 5 wt% and 15 wt% in the prepared binder (Examples 1 and 2 and Comparative Examples 1 and 2) As a result, it can be seen that the bottom ash generated in the synthetic natural gas production process can sufficiently fulfill its role in place of the fly ash commonly used as a conventional admixture for concrete Able to know.

When the bottom ash having a maximum particle size of not more than 75 탆 was collected by 50% from the upper portion through air classification (Example 3), the compressive strength measured by replacing 15% (Comparative Example 5). Therefore, when the finely divided bottom ash is used as an admixture for concrete, it can be seen that besides the economic and environmental effects of substituting cement, the compressive strength can be improved remarkably.

In addition, when the binder is mixed with the desulfurized slag fine powder in addition to the bottom ash (Examples 4 to 7), OH ^- of the desulfurization slag whose main component is Ca (OH) ₂ stimulates the vitreous coating of the amorphous bottom ash, It can be seen that the strength is improved. This effect is maximized in Example 7 containing 8% by weight of the desulfurized slag, except that the desulfurized slag contains 2% by weight (Comparative Example 3) or 10% by weight (Comparative Example 4) The effect of improving the compressive strength is insignificant.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (12)

Blend ash for concrete using bottom ash containing bottom ash powder generated by rapid cooling of coal raw materials during synthetic natural gas (SNG) manufacturing process.
The method of claim 1, wherein the bottom ash comprises 40 to 50 wt% silicon dioxide (SiO ₂ ), 20 to 30 wt% aluminum oxide (Al ₂ O ₃ ), 7 to 12 wt% calcium oxide (CaO) % and iron oxide (Fe ₂ O ₃₎ for concrete admixture using bottom ash containing 5 to 10% by weight.
The mixed material for concrete according to claim 1, wherein the bottom ash is generated by rapidly cooling the coal raw material at a cooling rate of 300 ° C / sec or more.
The concrete admixture for concrete according to claim 1, wherein the bottom ash powder has a maximum particle size of 75 탆 or less.
A binder for concrete comprising the admixture for concrete according to any one of claims 1 to 4.
6. The binder for concrete according to claim 5, wherein the admixture for concrete is contained in an amount of 5 to 25% by weight based on the total weight of the binder for concrete.
The binder for concrete according to claim 5, wherein the binder for concrete further comprises a desulfurized slag fine powder having a powder degree of 3000 cm ² / g or more generated in calcium hydroxide (Ca (OH) ₂ ) or molten iron pre-treatment.
[7] The binder for concrete according to claim 7, wherein the calcium hydroxide (Ca (OH) ₂ ) or the desulfurized slag fine powder is contained in an amount of 3 to 8% by weight based on the total weight of the binder material for concrete.
Recovering bottom ash generated in the process of producing synthetic natural gas (SNG); And
And crushing the recovered bottom ash using the bottom ash.
10. The method for producing an admixture for concrete according to claim 9, wherein the bottom ash pulverized in the pulverizing step is a bottom ash having a maximum particle size of 75 mu m or less.
The method according to claim 10, further comprising the step of collecting 45 to 55% from the upper portion of the ash floated through the air classifying the crushed bottom ash in the subsequent crushing step Gt;
The method for producing an admixture for concrete according to claim 11, wherein the bottom ash collected in the collecting step is a bottom ash having a maximum particle size of 45 탆 or less.

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