KR102649805B1 - Active Blast Furnace Slag Fine Powder Containing Slag Stimulanting Materials - Google Patents

Abstract

The present invention relates to activated blast furnace slag fine powder containing a slag stimulant using carbonates produced by fixing carbon dioxide in desulfurized gypsum and by-products of the steelmaking process as raw materials.
The present invention relates to “blast furnace crushed slag 94 to 97 wt%; Slag stimulant 2~5 wt%; and limestone within 1 wt% (excluding 0 wt%) mixed and crushed, and the slag stimulant is desulfurized gypsum, which is oil refinery ash generated in a Circulating Fluidized Bed Combustion (CFBC) boiler applied in the oil refining process. Carbonate prepared by drying the product reacted with water (H ₂ O) and carbon dioxide (CO ₂ ) at 85-105°C, and then pulverizing the agglomerated lumps to a powder fineness of 3,000-4,500 cm2/g. It provides an activated blast furnace slag fine powder, characterized in that the carbonate contains 40 to 45 wt% of CaO and 25 to 30 wt% of SO ₃ based on XRF analysis.

Description

Active blast furnace slag fine powder containing slag stimulant {Active Blast Furnace Slag Fine Powder Containing Slag Stimulanting Materials}

The present invention relates to activated blast furnace slag fine powder containing a slag stimulant using carbonates produced by fixing carbon dioxide in desulfurized gypsum and by-products of the steelmaking process as raw materials.

Climate change caused by greenhouse gases is a global problem. While technological efforts are being made to reduce _CO2 emissions in each industrial field, the cement industry is using industrial by-products such as blast furnace slag, fly ash, and stone dust sludge to replace cement, which emits a large amount of _CO2 during the firing process. Research on this topic is actively being conducted.

Among the above industrial by-products, blast furnace slag contains effective components that can be recycled into construction materials such as iron, carbon, and limestone, and has many advantages in improving the quality of cement by pulverizing it into fine powder. When a certain amount of general cement is replaced and mixed with blast furnace slag fine powder, the performance of concrete such as flow characteristics, drying shrinkage, long-term strength, freeze-thaw resistance, and heat resistance is improved.

However, as fine powder of blast furnace slag is used as a binder, there is a problem of lowering the initial strength compared to the use of general cement, so it was necessary to include an alkali stimulant that promotes latent hydraulic reaction as a binder component, and it is necessary to include alkaline stimulant as a binder component that promotes latent hydraulic reaction. Desulfurized gypsum, an industrial by-product, has been used as an alkali stimulant for blast furnace slag fine powder.

1. Registered Patent 10-1286030 “Blast furnace slag cement composition containing refined ash” 2. Registered Patent 10-2458784 “Method for producing inorganic compounds using recycled resources to reduce greenhouse gas emissions” 3. Registered Patent 10-2414541 “Reactor and carbonation device including the same” 2. Registered Patent 10-1482017 “Method for synthesizing pure calcite from carbonation reaction of desulfurized gypsum using CO2 capture intermediate product” 3. Registered Patent 10-0934379 “Binder and manufacturing method for steel sintering using an organic binder and method for processing by-products of the sintering process using a sintering binder”

1. Song Gyeong-seon, Kim Won-baek, Park Sang-won, Seo Chang-yeol, and Ahn Ji-hwan, "Phase change of high-purity calcium carbonate produced by flue gas desulfurization gypsum carbonation reaction", Korea Society of Industrial Chemistry Research Paper Abstract Collection 2016, No. 1, 2016. 2. Myeong-gyu Lee, “Study on mineral carbonation of desulfurized gypsum for carbon dioxide reduction”, PhD thesis, University of Science and Technology, 2013.

The present invention moves away from the passive CO ₂ reduction technology that replaces cement and applies an active CO ₂ reduction technology that fixes CO ₂ in a solid material. Carbonate that fixes CO ₂ in desulfurized gypsum is used as a slag stimulant. The purpose is to provide technical means for use.

In order to solve the above-mentioned problem, the present invention is a mixture of "blast furnace crushed slag 94-97 wt%; Slag stimulant 2~5 wt%; and limestone within 1 wt% (excluding 0 wt%) mixed and crushed. The limestone serves as a grinding aid, and the slag stimulant is used in a Circulating Fluidized Bed Combustion (CFBC) boiler applied to the oil refining process. After reacting desulfurized gypsum, which is oil refinery ash produced in , with water (H ₂ O) and carbon dioxide (CO ₂ ), the product is dried at 85 to 105°C, and then the aggregated lump is ground to a fineness of 3,000 to 4,500 ㎠/g. An active blast furnace comprising carbonates produced by disintegration, wherein the carbonates contain 40 to 45 wt% CaO and 25 to 30 wt% SO ₃ based on XRF analysis. Slag fine powder” is provided.

The slag stimulant may include 25 wt% or less (excluding 0 wt%) of Na ₂ SO ₄ or 80 wt% or less (excluding 0 wt%) of anhydrous gypsum (CaSO ₄ ).

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The effects of the present invention are as follows.

1. By fixing CO ₂ in desulfurized gypsum to manufacture slag stimulant, CO ₂ emissions can be actively reduced.

2. By providing a slag stimulant that has an effect equal to or greater than that of conventional desulfurized gypsum, it can further promote the use of blast furnace slag fine powder and contribute to reducing CO ₂ emissions by reducing cement usage.

3. Provides activated blast furnace slag fine powder with improved initial strength development performance.

[Figure 1] is a schematic diagram of the carbonate production process.
[Figure 2] is a photograph of carbonate in powder form.
[Figure 3] is an XRD component analysis graph of oil refinery ash and carbonate.
[Figure 4] is a comparative table of XRF chemical analysis of oil refinery ash and carbonate.

Desulfurized gypsum is a by-product generated in the process of removing sulfur oxides (SOx) generated when the sulfur (S) component contained in fuel such as coal is burned by reacting it with an absorbent (mainly limestone). CaSO ₄ and CaO are the main components. It is contained. The CaO component has the effect of promoting the latent hydraulic reaction of blast furnace slag fine powder. Therefore, desulfurized gypsum is used as a cement substitute or an ingredient in admixtures.

In the oil refining process, a Circulating Fluidized Bed Combustion (CFBC) boiler is applied to prevent the release of hazardous substances into the air, and the waste gas generated after coke (C) and limestone (CaCO ₃ ) are burned together in the fluidized bed combustion furnace. Oil refinery ash can also be called desulfurized gypsum.

In desulfurized gypsum, the CaO component reacts with water (H ₂ O) to produce calcium hydroxide (Ca(OH) ₂ ) (see [Formula 1] below), and the produced calcium hydroxide (Ca(OH) ₂ ) is converted into carbon dioxide (CO ₂ ). ) to produce calcium carbonate (CaCO ₃ ) (see [Formula 2] below).

[Formula 1]

CaO + H ₂ O → Ca(OH) ₂

[Formula 2]

Ca(OH) ₂ + CO ₂ → CaCO ₃

By applying the above reaction, carbon dioxide generated from various factories can be fixed as carbonate (captured to form a solid material component). Specifically, as shown in [Figure 1], carbon dioxide can be fixed in desulfurized gypsum by controlling the reaction [Formula 1] in the water tank and controlling the reaction [Formula 2] in the reaction tank.

By reacting oil refinery ash with water (H ₂ O) and carbon dioxide (CO ₂ ) according to the above reaction mechanism, it contains 40 to 45 wt% of CaO and 25 to 30 wt% of SO ₃ based on XRF analysis. carbonate is produced.

The product obtained by reacting oil refinery ash (desulfurized gypsum) with water and carbon dioxide is dried at 85 to 105°C, and then the agglomerated lumps are pulverized to a powder size of 3,000 to 4,500 ㎠/g, similar to that of existing desulfurized gypsum. ), thereby producing carbonate powder as shown in [Figure 2]. Desulfurized gypsum can be called "carbonate" when it reacts with water and carbon dioxide, but it needs to be dried because it contains moisture. However, after the above carbonate is dried, it remains in the form of lumps, so the process of dispersing it into powder is described as "disintegration." There is a conceptual difference from “crushing,” which involves breaking and separating solid lumps.

[Figure 3] is an XRD component analysis graph of specific oil refinery ash and carbonate produced by reacting the refined oil refinery ash with water and carbon dioxide, and [Figure 4] is an XRF chemical analysis comparison table. XRF is related to atomic quantitative analysis and does not provide molecular shape analysis results, so the degree of carbonation can be analyzed by XRD crystal analysis.

Since the above carbonates have an SO ₃ content of more than 25 wt% based on XRF analysis, they are gypsum specified in KS F 2563 (blast furnace slag fine powder), KS L 5210 (blast furnace slag cement), and KS L 5313 (natural gypsum for cement). It can be used as a stimulant for slag products (slag cement, blast furnace slag fine powder).

However, there is a risk that the performance as a stimulant may be deteriorated due to the decrease in CaO content compared to the existing desulfurized gypsum. However, by using anhydrous gypsum (CaSO ₄ ) or NaSO ₄ ) as a component of the slag stimulant composition in the carbonate, the existing gypsum It can achieve performance equivalent to or better than desulfurized gypsum, and can also contribute to reducing CO ₂ emissions by using carbon dioxide fixation materials. Since the by-product of the sintering process during the steelmaking process is also a NaSO ₄ component, the by-product of the sintering process can be applied as a raw material for slag stimulant composition.

Below, the present invention will be described along with several test examples.

Specimens mixed with 450 g of binder, 1,350 g of fine aggregate, and 50 wt% of water-binder ratio were manufactured and compressive strength tests were conducted for each age (3 days, 7 days, and 28 days). Each of the examples below is based on the binder composition. There is a difference.

1. Slag cement strength development test according to slag stimulant composition

[Table 1] below shows comparative examples and examples of mortar compositions using slag cement as a binder. The applied slag cement is composed of 39 wt% of ordinary Portland cement, 57 wt% of blast furnace slag fine powder, and 4 wt% of slag stimulant.

Comparative Example 1 is a typical slag cement, in which desulfurized gypsum was applied as a slag stimulant.

In each Example, other mixing conditions were the same as Comparative Example 1, but only the slag stimulant component was different, and the components of the slag stimulant were classified according to the weight ratio of carbonate and carbonate as described above.

In each of the following examples, the carbonates analyzed as shown in [FIG. 3] and [FIG. 4] were applied, and the by-product of the sintering process during the steelmaking process was applied as the nettle.

[Table 2] below shows the compressive strength test results by age for Comparative Example 1 and Examples above.

In Example 1, in which a slag stimulant containing 100 wt% of carbonate was applied, the compressive strength at 3 days and 28 days of age was maintained at the same level as Comparative Example 1 and slightly lower, but the compressive strength at 7 days was rather high.

Looking at Examples 2 to 6, in which compressive strength tests were conducted for each age as the slag stimulant content was increased to 5 to 25 wt%, slag stimulant containing 80 wt% carbonate and 20 wt% slag stimulant was mixed. In Example 5 where ash was applied, the compressive strength for each ash was found to be the best.

Example 6, which applied a slag stimulant mixed with 75 wt% carbonate and 25 wt% carbonate, still showed excellent compressive strength at 3 and 7 days of age compared to Comparative Example 1 and Example 1, but at 28 days of age. It was found that the strength decreased somewhat.

Therefore, when applying the carbonate as a slag stimulant, it is preferable to substitute a portion of the carbonate with carbon dioxide in a range of 25 wt% or less.

Examples 7 to 9 shown in [Table 3] below are shown separately according to the weight ratio of carbonate and anhydrous gypsum compared to Example 1 in which a slag stimulant consisting of 100 wt% of carbonate was applied. [Table 3] shows the compressive strength test results by age for each example.

Looking at Examples 2 to 6, in which compressive strength tests were conducted by age as the anhydrous gypsum content was increased from 20 to 100 wt% in the slag stimulus material of Example 1 consisting of 100 wt% of carbonate, 60 wt of carbonate was obtained. In Example 8, which applied a slag stimulant mixed with 40 wt% anhydrous gypsum, the compressive strength at each age was the best.

Thereafter, as the mixing amount of the anhydrous stone furnace was increased, the compressive strength by age tended to decrease. Up to Example 10, the compressive strength by age was expressed at a level equivalent to that of Comparative Example 1, which was a typical slag cement composition, but in Example 11. It was found that the compressive strength decreased relatively significantly at 3 and 28 days of age.

Therefore, when applying the carbonate as a slag stimulant, it is preferable to replace a portion of the carbonate with anhydrous gypsum and apply the anhydrous gypsum in a range of 80 wt% or less.

[Table 4] below compares the compressive strength by age according to whether the carbonate applied as a slag stimulant component was pulverized under the same mortar mixing conditions. All of the carbonates applied in Examples 1 to 11 above were obtained by reacting desulfurized gypsum with water (H ₂ O) and carbon dioxide (CO ₂ ), drying the product at 100°C, and then clumping the lumps with a powder fineness of 3,500 cm2/g. It was dismantled as much as possible.

In Examples 3-1 and 3-2, which were added to the mortar mixture and mixed under the same conditions as Examples 3 and 5 without applying the disintegration process to carbonates, the compressive strength was found to decrease at all ages. .

2. Blast furnace slag fine powder activity test

[Table 5] below shows comparative examples and examples of mortar compositions using blast furnace slag fine powder as a binder.

As described above, a specimen mixed with 450 g of binder, 1,350 g of fine aggregate, and a water-binder ratio of 50 wt% was manufactured and compressive strength tests were performed at each age (3 days, 7 days, and 28 days), but the The binder is a conventional blast furnace slag fine powder, which is ground into fine powder by mixing 99 wt% of crushed slag and 1 wt% of limestone (acting as a grinding aid).

Examples 12 and 13 were ground into fine powder by mixing 95 wt% of crushed slag, 4 wt% of slag stimulant, and 1 wt% of limestone (serving as a grinding aid), and the slag stimulant was a mixture of carbonate and limestone. In Examples 12 and 13, the contents of carbonate and citron were varied. In Examples 12 and 13, carbonates, like the carbonates applied in Examples 1 to 11 above, were pulverized into powder and added to the crushed slag grinding process line together with limestone serving as a grinding aid.

[Table 6] below shows the compressive strength test results by age for Comparative Example 2 and Examples to test the activity of blast furnace slag fine powder according to the application of slag stimulant.

When compared to Comparative Example 1 reviewed previously, it was confirmed that the initial strength (3-day strength) of the mortar composition using blast furnace slag fine powder as a binder was reduced, and Example 12 (carbonoxide 90 wt%) containing the slag stimulant of the present invention was confirmed to be reduced. In Example 13 (mixing 80 wt% of carbon dioxide and 20 wt% of turmeric), it was confirmed that the strength was improved after 3 days of age. Considering that the 3-day strength is generally considered to be equivalent to the ±0.5 MPa range, the 2.3 MPa improvement effect shown in Example 13 as well as the 1.5 MPa improvement effect shown in Example 12 are significant initial strength improvement effects. As a result, it is understood that the latent hydraulic reaction of blast furnace slag is promoted by the application of slag stimulant.

Meanwhile, the strengths at 7 days and 28 days were shown to be at the same level overall, and it was confirmed that the strength at 28 days of Example 13 was slightly improved compared to Comparative Example 2.

In the present invention, the blast furnace slag fine powder into which the above-mentioned slag stimulant was added during the crushed slag grinding process is referred to as "activated blast furnace slag fine powder", and the general blast furnace slag applied to the slag cement shown in Comparative Example 1 and Examples 1 to 10 The initial strength can be further improved by applying the activated blast furnace slag fine powder instead of the fine powder.

Above, this specification has described related content focusing on the embodiments of the present invention, and the terms described in this specification are merely used in a general sense to easily explain the technical content of the present invention and aid understanding of the present invention. The scope of is not limited to the dictionary meaning of the term. In addition to the embodiments disclosed in this specification, other modifications based on the technical idea of the present invention can also be implemented.

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Claims (9)

Blast furnace crushed slag 94~97 wt%; Slag stimulant 2~5 wt%; and limestone within 1 wt% (excluding 0 wt%) mixed and crushed, wherein the limestone serves as a grinding aid,
The slag stimulant is a product obtained by reacting desulfurized gypsum, which is oil refinery ash generated in a Circulating Fluidized Bed Combustion (CFBC) boiler applied in the oil refining process, with water (H ₂ O) and carbon dioxide (CO ₂ ). It contains carbonate prepared by drying at 105°C and then pulverizing the agglomerated lumps to a powder fineness of 3,000 to 4,500 cm2/g,
The carbonate is an activated blast furnace slag fine powder, characterized in that it contains 40 to 45 wt% of CaO and 25 to 30 wt% of SO ₃ based on XRF analysis.
In paragraph 1:
The slag stimulant is an activated blast furnace slag fine powder, characterized in that it contains 25 wt% or less (excluding 0 wt%) of Na ₂ SO ₄ .
In paragraph 2,
The activated blast furnace slag fine powder is characterized in that the mango is a by-product of the sintering process during the steelmaking process.
In paragraph 1:
Activated blast furnace slag fine powder, characterized in that it contains 80 wt% or less (excluding 0 wt%) of anhydrous gypsum (CaSO ₄ ). delete delete delete delete delete