WO2023075512A1 - Method for producing low carbon slag powder using refining slag, and quick-setting admixture and cement composition using slag powder prepared thereby - Google Patents

Abstract

The present invention relates to: a low-carbon cement composition using refining slag; and a process technique for same. According to the present invention, it is possible to improve a process for refining slag, which has conventionally been disposed in landfills without being utilized, and produce a quick-setting cement composition without a firing process through the processes of particle size sorting and magnetic sorting of the refining slag, thus having the effect of providing a quick-setting cement composition having a low carbon footprint.

Description

Low-carbon slag powder manufacturing method using refining slag, quick-setting admixture and cement composition using the slag powder prepared by the above method

The present invention relates to a method for producing slag powder using refined slag, and relates to a method for producing high-quality slag powder through an environmentally friendly manufacturing process and reducing carbon emissions.

The present invention relates to a quick-setting and quick-setting cement composition using the slag powder.

Looking at the domestic steel slag generation and usage, more than 26 million tons of slag is generated annually, of which 15 million tons of blast furnace slag is used as a cement admixture for more than 90%. Most of the oxidized slag from converters and electric furnaces weighing around 10 million tons is used as aggregate for roads and embankments, and both slags have a recycling rate of over 99%.

However, it is estimated that about 1 million tons of secondary refining slag (or reducing slag) generated in converters and electric furnaces is generated annually, but most of them are not utilized and steelmakers are experiencing difficulties in processing. (See Fig. 2a. Photograph of discharging molten slag to a yard)

Refining slag contains 10-65% of C2S (2CaO SiO2) in the process, and when discharged in a molten state at about 1,600℃, C2S, which existed in the α phase, is gradually cooled and transitions to the γ phase around 830℃. In this process, it is powdered through a self-differentiation process for several hours to several days by volume expansion by 1.1 times. Due to this, it cannot be used as aggregate, and water is continuously sprayed on the yard due to scattering dust, and alkaline leachate is generated in the process, causing environmental problems. This is pointed out as the main cause of environmental pollution at the outdoor sites of steel mills. (See Fig. 2d. Photo of alkali leachate generation)

Due to the nature of the process, Si or Al is added as a deoxidizing agent along with quicklime (CaO) for desulfurization. In the case of CA-based refining slag, it contains 40-50% of CaO, 20-30% of Al2O3, and 5-15% of SiO2 as main oxides, and based on the above oxides, C12A7 (12CaO 7Al2O3, Mayenite), a quick-setting mineral It contains about 40-55% of γ-C2S and contains 10-30% of γ-C2S. Even slow-cooled refining slag shows low reactivity to γ-C2S but fast hydration by C12A7.

Although CA-based slag contains a large amount of quick-setting minerals, it is currently mixed with CS-based slag and discharged, thereby reducing the value of CA-based slag and causing severe quality fluctuation of discharged slag. Furthermore, in most steel makers, by mixing refining slag with oxidized slag and converter slag for discharge treatment (see Fig. 2b, photo of mixed discharge with oxidized slag), the value of oxidized slag and converter slag as aggregates is reduced, and at the same time, refining slag It is a situation that makes the value of use useless. In addition, as described above, in the cooling process after discharge, most of the steel yarns are sprinkled with water, thereby losing their value as a cement composition raw material. (See Fig. 2c. Photos of watering during slag treatment)

On the other hand, the cement industry, as an industry with high greenhouse gas emissions, is facing an unprecedented crisis to achieve the carbon emission target compared to 2030 at the level of 11% of the total emissions of the industry. The main raw material of cement is limestone, and in the process of firing limestone It emits 82.3% of the total emissions of the cement industry, and when producing 1 ton of cement, 0.83 CO2·ton.eq. discharge

Accordingly, as technical means and methods for carbon neutrality in the cement industry, the use of decarboxylation raw materials, the use of alternative fuels, the improvement of equipment and process efficiency, and CCUS are proposed. It was confirmed that it was the use of alternative raw materials with low emissions). Therefore, it is time to develop various alternative low-carbon raw materials for the cement industry.

In order to solve the above problems, the present invention is a quick-setting or quick-setting cement composition that simultaneously possesses high-quality quick-setting performance and carbon emission reduction effect through a dry slow cooling process for CA-based slag without the need for a firing process. It was devised based on the fact that it can be manufactured.

As prior literature, Korean Patent Publication No. 10-2017-0122919 describes a 'hydraulic binder using dry annealed CA-CS steel slag'. This relates to the development of hydration characteristics and strength by mixing gypsum with CA-CS-based slag. The focus on dry slow cooling is somewhat similar to that of the present invention, but the present invention is a technology that focuses on the characteristics of CA-based slag, and is a basic I'd say there's a difference. In addition, Korean Patent Registration No. 10-1333084 discloses 'an early strong cement composition containing blast furnace slag and CSA cement and concrete containing the same'. Looking at the identification item [0027], while mainly using blast furnace slag as a main hardening raw material, it will be different from the present invention, which focuses on C12A7 raw materials, as not using C12A7 raw materials.

An object of the present invention is to provide a method for producing high-quality CA-based slag powder that is environmentally friendly and has low carbon emissions from refining slag.

An object of the present invention is to provide a quick-setting and quick-setting cement composition using the CA-based slag powder prepared by the above method.

An object of the present invention is to use a combination of classified slags to suit the properties of the slags classified according to the sorting standard particle size.

The solution includes a process separation step of preparing CA-based slag in a molten state;

A dry slow cooling step of producing cooled slag by cooling the CA-based slag in an enclosed space without contact with moisture;

A particle size screening step of classifying the cooled slag into slag exceeding the screening standard particle size and slag below the screening standard particle size according to the screening standard particle size;

A coarse crushing step of crushing the slag exceeding the screening standard particle size to produce crushed slag;

A magnetic sorting step of magnetically sorting the crushed slag into crushed Fe high content slag and crushed Fe low content slag, and magnetically sorting the slag below the sorting standard particle size into Fe high content slag and low Fe slag;

And finely pulverizing the crushed Fe low content slag to prepare a first fine powder having a powder degree of 5,000 to 7,000 cm ² /g, and finely pulverizing the low Fe slag among the slags below the screening standard particle size to have a powder degree of 5,000 to 7,000 cm ² / It is a method for producing low-carbon slag powder, characterized in that it is produced with the second quick-setting fine powder of g

In the above, in the dry slow cooling step, it is characterized in that a process of recovering and recycling waste heat and collecting fine powder generated during cooling to generate dust-collected fine powder is additionally performed.

In the above, in the magnetic separation step, the fine powder collected together with the slag below the screening standard particle size is classified into Fe high content slag and Fe low content slag.

In the above, the screening standard particle size is characterized in that 10mm ~ 0.6mm.

In the above, the high Fe content slag recycling step is added after the magnetic separation step, characterized in that the high Fe content slag among the crushed Fe high content slag and the slag below the screening standard particle size is separately classified and accumulated.

A solution is a quick-settling agent manufactured using the first quick-setting fine powder manufactured by the above method.

The solution is a quick setting agent prepared by including the first quick setting fine powder and the second quick setting fine powder manufactured by the above method.

The solution is a quick-setting cement composition comprising at least one selected from the first fine powder and the second rapidly setting fine powder prepared by the above method, and a setting retardant.

In the above, the setting retardant is characterized in that at least one selected from tartaric acid, sodium citrate, gluconic acid and anhydrous citric acid.

The effect of the present invention is to improve the process of refining slag, which has been treated in landfills without existing utilization, and to provide a quick-setting cement composition having low carbon emissions by producing a quick-setting admixture without a firing process through a particle size and magnetic separation process. there is.

In addition, when a cement composition using refining slag is used, it can replace ordinary Portland cement and calcium aluminate-based cement. It has the effect of significantly reducing the amount of carbon emissions generated.

In addition, the cement composition contains 50% or more of CA minerals such as C12A7 and C3A and has excellent quick-setting properties, so it can be used for quick-setting compositions. It can be used for concrete applications that require strength development.

In addition, in the process of magnetic separation of refining slag, separately selected high Fe content slag is separated by magnetic force, so that high added value can be achieved as an alternative raw material for iron ore in steelmakers and as a raw material for steel processing.

1 is a block diagram showing a method for producing a quick-setting low-carbon cement composition using dry slowly cooled slag according to an embodiment of the present invention.

2a to 2d are photographs of a conventional refining slag treatment method.

3a to 3d are photographs of the results of the particle size screening step in the manufacturing method according to an embodiment of the present invention.

4 is a table showing the particle size distribution of slag after the dry slow cooling step in the manufacturing method of an embodiment of the present invention.

5A to 5C are photographs of the results of the magnetic separation step in the manufacturing method according to an embodiment of the present invention.

6 is a graph showing the particle size distribution of the slag fine powder after the pulverization step in the manufacturing method of an embodiment of the present invention.

7 is a graph showing the compressive strength as a hydration characteristic of the fine slag powder derived from 5 mm under size of the present invention.

The terms or words used in this specification and claims conform to the technical spirit of the present invention based on the "principle that the inventor can appropriately define the concept of terms in order to explain his or her invention in the best way" It should be interpreted as the meaning and concept of

Therefore, the configurations shown in the drawings described in this specification are only the most preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents and modifications that can replace them at the time of this application It should be understood that there may be examples.

In particular, in the present invention, 'refining slag' is a term used interchangeably with 'reduction slag', and it should be understood that the technical idea related to 'refining slag' described in this specification extends to 'reduction slag'.

Example 1. Manufacturing method of quick-setting low-carbon cement composition

* Figure 1 is a block diagram showing a manufacturing method according to an embodiment of the present invention. The manufacturing method includes a process separation step, dry annealing step, particle size screening step, coarse crushing step, magnetic separation step and fine grinding step.

1) Process Separation Step

This step is a step of securing and preparing CA-based slag in a molten state that is not mixed with CS-based slag among refining slag. In the discharge process, separate ports are provided to discharge oxidized and converter slag and refining slag to each port, and separate ports are provided so that CA-based and CS-based are separately discharged from refining slag so that they are discharged to each port. .

That is, in order to utilize CA-based slag for low-carbon quick-setting cement, it is collected in a separate port when discharged from the melting stage and stored separately for the slow cooling process.

Table 1 below shows oxide composition ratios according to CS-based and CA-based slags. CS-based slag and CA-based slag show a large difference in oxide composition, and in particular, a large difference in SiO2 and Al2O3 contents due to process characteristics depending on the type of reducing agent used. Referring to Table 1, the CS-based Al2O3 content is 5-15% and the CA-based content is 25-35%. The currently secured slag is a mixed slag, and Table 1 below is self-separated, and it can be seen that there is some deviation in the component composition ratio.

oxide composition ratio division
stocking date CS-based slag CA based slag CaO Fe ₂ O ₃ Al ₂ O ₃ SiO ₂ MgO CaO Fe ₂ O ₃ Al ₂ O ₃ SiO ₂ MgO 2021. 1st 50.2 1.2 14.6 20.2 11.2 54.7 1.1 26.3 7.0 6.7 2021. 2nd 44.8 2.3 13.9 22.6 12.1 54.4 0.8 27.7 6.9 7.3 2021. 3rd 36.1 21.7 9.4 17.6 8.0 49.1 2.1 33.3 5.2 6.6 2021. 4th 40.3 6.2 12.3 23.2 11.9 51.3 1.2 29.0 6.3 6.7 2021. 5th 36.1 21.7 9.4 17.6 8.0 46.2 5.1 32.6 6.2 6.6

However, if the process is separated and only CA-based slag is used alone, it is possible to easily control the Al2O3 content variation range of 10-35% of the mixed state refining slag to 25-35%, resulting in high concentration (more than 50%) CA It is possible to secure raw materials for slag containing (Calcium aluminate) minerals (C12A7 (Mayenite) and C3A, etc.). 2) Dry slow cooling step

In order to prevent C12A7 and C3A, which are quick-setting minerals, from losing their cementitious properties through watering treatment, the molten slag is moved to a cooling place using a pot and then completely differentiated without contact with water. That is, the slag discharged in a molten state is maintained and stored in the pot without contact with moisture until cooled to room temperature and moved to the sorting field.

In order to dry the refining slag, an enclosed space without contact with moisture is required, and waste heat emitted during the cooling process of high-temperature molten slag of 1600℃ or higher in the enclosed space can be recovered by high-temperature hot air through an air circulator. And, as the fine powder to be differentiated exists as a fine powder of 25% or more and 150 μm or less, as shown in FIG. 4, it is possible to secure a fine powder of 150 μm or less through a dust collector without a grinding process.

Dry slow-cooled refining slag cooled without contact with water can maintain its value as a raw material for quick-setting cement compositions as the minerals such as C12A7 and C3A it contains maintain high reactivity.

3) Particle Size Selection Step

3a to 3d are photographs of the results of the particle size screening step in the manufacturing method according to an embodiment of the present invention. 3a: slag resulting from dry annealing step, 3b, 3c: particle size exceeding 5mm, 3d: particle size less than 5mm. 4 is a table showing an example of the particle size distribution of slag after the dry slow cooling step in the manufacturing method of an embodiment of the present invention.

The dry annealed refining slag is moved to a particle size sorting field and classified into ① 5mm over size and ② 5mm under size through particle size classification based on a 5mm sieve. Dry slow-cooled refining slag shows a big difference in rapid crystallization and initial exothermicity depending on the particle size, so it is to classify the particle size and use it differently.

However, as the particle size of slag differs depending on the composition and environmental changes at the time of discharge, the range of the particle size classification sieve is 10mm to 0.6mm depending on the design conditions, and there is a possibility of variation depending on the required product amount. That is, the range of the sieve may vary according to the selection standard particle size.

In other words, the technical spirit of the present invention includes combining and using slags to suit the properties of the slags classified according to the selection standard particle size, and although the details based on the properties of the slags classified on the basis of 5mm are described in this specification, Different sorting standard particle sizes are applied and slags can be used in combination through the same property analysis. Therefore, it is natural that the present invention can also be applied by adopting a selection standard particle size within the range of 10 to 0.6 mm to fit the range of the fine aggregate standard particle size.

4) Crude crushing step

In the case of over size of 5 mm, it exists in lumps of various sizes (5 mm to several tens of cm), and it is crushed into 5 mm under size using a crusher. Depending on the design conditions, the standard particle size for screening may vary.

5) Self-selection stage

① 5mm under size slag obtained by crushing 5mm over size slag and ② 5mm under size slag are all moved to a magnetic separator in a classified state and are magnetically separated. 5A to 5C are photographs of results of the magnetic separation step in the manufacturing method according to an embodiment of the present invention. 5a, 5b: example of magnetic separation, 5c: sample magnetically separated by particle size.

Dry slow-cooling refining slag shows a maximum Fe oxide content of 10% or more when pulverized without a magnetic separation step, which is a factor in reducing strength when used as a binder. In addition, since high Fe content can reduce the efficiency at the time of grinding due to ductility, it is necessary to control within 2% through Gauss control of the sorter during magnetic sorting.

Furthermore, the slag with high Fe oxide content selected by magnetic force can be reintroduced as a raw material for processing of steel makers, and can also be used as an Fe source for cement makers.

Table 2 and Table 3 below describe the oxide and mineral compositions after the magnetic separation step by particle size.

CaO Al2O3 SiO2 MgO SO3 Fe2O3 Etc Sum 5mm over + coarse crushing 48.6 30.3 5.74 10.7 3.66 0.62 0.38 100 5mm under size 47.1 30.4 8.29 7.67 3.4 2.14 One 100

granularity CaO Al2O3 SiO2 MgO SO3 Fe2O3 5mm over
+Crushing 48.6 30.3 5.74 10.7 3.6 0.6 2.5mm 47.3 26.3 6.9 8.0 3.2 2.2 1.2mm 49.1 27.7 7.1 10.0 3.9 0.8 0.6mm 49.2 29.0 7.6 8.2 4.1 0.6 0.3mm 49.1 30.5 7.0 6.6 3.3 2.0 0.15mm 49.3 31.5 6.2 6.5 3.3 1.6

6) After magnetic screening in the pulverization stage, ① 5mm over size + coarsely crushed slag and ② 5mm under size slag, excluding samples with high Fe content, are finely ground to a fine powder with a fineness of 5,000 to 7,000 cm ² /g through fine pulverization. manufactured with

① 5mm over size + crushing slag and ② 5mm under size slag have a shape difference according to the degree of self-differentiation due to the volume change of the C2S phase transition process. high.

Example 2. Low-carbon rapid settlement using dry slow-cooling refining slag

Normally, Portland cement or quick-setting cement emits 0.8-0.95 tons of CO2 when producing 1 ton in the firing process during the manufacturing process, and it is reported that more than 82% is emitted in the double firing process in particular. Therefore, since the slag used in Example 1 does not require a firing process for fine powder, it is possible to significantly reduce carbon emissions by approximately 0.15 CO2·ton.eq., even excluding only emissions during the firing process.

In addition, conventionally produced CA series cement products form a high unit price line by using bauxite, an expensive raw material, as an aluminate-based source, but the slag fine powder according to Example 1 is based on by-products and reduces the process. It is possible to secure price competitiveness through

As described above, due to the influence of the C2S phase transition process, ① 5 mm over size slag is coarsely crushed, magnetically separated, and pulverized, and the initial reactivity is very fast due to the high content of C12A7 minerals and C3A (3CaO Al2O3) with rapid crystallization, It exhibits high exotherm in water. In this case, it shows a high content up to 65%. Accordingly, when mixing with water, rapid hardening occurs within 1 minute, and heat of hydration of 100℃ or more occurs within 5 minutes.

Therefore, ① fine powder using 5mm over size slag condenses quickly and is suitable for use in rapid setting that requires initial hardening.

6 is a graph showing the particle size distribution of the slag fine powder after the pulverization step in the manufacturing method of an embodiment of the present invention. In Table 4 below, condensation and exothermic characteristics are described in the case of fine powder derived from 5 mm over size and unsatisfied powder derived from 5 mm under size.

division condensation time
(H:M) heat of hydration peak first resolution closing temperature Time (H:M) OPC 4:50 7:00 28 - slag
fine powder 5mm over 0:00 0:01 105 0:05 5mm under 0:03 0:09 65 0:12

The rapid setting as Example 2 is summarized as follows: A sample with high Fe content by magnetic separation after dry annealing of CA-based slag among refining slag through process separation and crushing of 5 mm over size slag through particle size screening is excluded, and fine powder quick-settling having a powder degree of 5,000 to 7,000 cm ² /g as a selected raw material Example 3. Low-carbon quick-setting cement composition using dry slow-cooling refining slag

② Fine powder using slag derived from 5mm under size also contains 40 to 60% of CA minerals, so it shows rapid crystallinity when mixed with water. However, compared to the sample ①, the rapid crystallinity is relatively low. However, considering that it is possible to secure working time by using a retardant after mixing the sample with water, it can be molded after mixing and used as a quick-setting cement that requires rapid strength development (more than 3MPa in 3 hours). Aged 28 days strength can also express more than 20MPa.

The composition of Example 3 also has the characteristics of low carbon and price competitiveness like Example 2. In addition, all raw materials, except for a small amount of retardant, are recycled from industrial by-products to increase added value, and all refining slag is recycled to have the environmental advantage of being a zero-waste process product.

7 is a graph showing the compressive strength as a hydration characteristic of the fine slag powder derived from 5 mm under size of the present invention. (SCLFS: test sample)

The composition as Example 3 is summarized as follows: Through process separation, only CA-based slag among refining slag (or reduction slag) is subjected to dry slow cooling, and ② 5 mm under size slag is magnetically separated through particle size screening to obtain Fe content. Excluding this high sample, the fine powder with a fineness of 5,000 to 7,000 cm ² /g as the selected raw material, and the setting retardant added to solve the difficulty of securing working time in the rapid setting are tartaric acid, sodium citrate, gluconic acid and A quick-setting cement composition containing 0.2-2.0% of at least one selected from anhydrous citric acid.

Example 4. Low carbon quick settlement using dry slowly cooled refining slag

*In Example 2, an expedited setting using fine powder derived from 5 mm over size was proposed, but it can be used as an expedited setting by mixing fine powder derived from 5 mm over size and fine powder derived from 5 mm under size. Of course, it can be used when it is necessary to adjust the rapid setting initial hardening according to the demand of the consumer according to the field situation. This is possible because the content of each fine powder can be adjusted based on the characteristics of each fine powder.

Example 5. Low carbon cement composition using dry slowly cooled refining slag

In Example 3, a cement composition using fine powder derived from 5 mm under size was presented, but it is also possible to prepare a cement composition by mixing fine powder derived from 5 mm over size. This can also be used when design changes are required according to field conditions. This is also possible because the content of each fine powder can be adjusted based on the characteristics of each fine powder.

Claims (9)

Process separation step of preparing CA-based slag in a molten state; A dry slow cooling step of producing cooled slag by cooling the CA-based slag in an enclosed space without contact with moisture; A particle size screening step of classifying the cooled slag into slag exceeding the screening standard particle size and slag below the screening standard particle size according to the screening standard particle size; A coarse crushing step of crushing the slag exceeding the screening standard particle size to produce crushed slag; A magnetic sorting step of magnetically sorting the crushed slag into crushed Fe high content slag and crushed Fe low content slag, and magnetically sorting the slag below the sorting standard particle size into Fe high content slag and low Fe slag; And finely pulverizing the crushed Fe low content slag to prepare a first fine powder having a powder degree of 5,000 to 7,000 cm ² /g, and finely pulverizing the low Fe slag among the slags below the screening standard particle size to have a powder degree of 5,000 to 7,000 cm ² / A method for producing a low-carbon slag powder comprising the steps of preparing a first fine powder and a second fine powder prepared from the second fine powder of g. The method of claim 1, In the dry slow cooling step, a process for recovering and recycling waste heat and collecting fine powder generated during cooling to produce a dust-collected fine powder is further performed. The method of claim 2, In the magnetic separation step, the fine powder collected together with the slag below the screening standard particle size is classified into Fe high content slag and Fe low content slag, characterized in that, a method for producing low carbon slag powder. The method of claim 1, The method for producing a low-carbon slag powder, characterized in that the screening standard particle size is 10mm ~ 0.6mm. The method of claim 1, By adding the Fe high content slag recycling step after the magnetic separation step, Method for producing a low-carbon slag powder, characterized in that the crushed Fe high-content slag and the Fe-high content slag among the slags below the screening standard particle size are separately classified and accumulated. Process separation step of preparing CA-based slag in a molten state; A dry slow cooling step of producing cooled slag by cooling the CA-based slag in an enclosed space without contact with moisture; A particle size screening step of classifying the cooled slag into slag exceeding the screening standard particle size and slag below the screening standard particle size according to the screening standard particle size; A coarse crushing step of crushing the slag exceeding the screening standard particle size to produce crushed slag; A magnetic sorting step of magnetically sorting the crushed slag into crushed Fe high content slag and crushed Fe low content slag, and magnetically sorting the slag below the sorting standard grain size into Fe high content slag and low Fe slag; The crushed Fe low-content slag was pulverized to prepare a first fine powder having a powder degree of 5,000 to 7,000 cm ² /g, and the Fe low-content slag among the slags below the screening standard particle size was pulverized to have a powder degree of 5,000 to 7,000 cm ² /g A first quick-quick fine powder and a second quick-quick fine powder manufacturing step to prepare from the second quick-quick fine powder of; and A quick-settling manufacturing method consisting of; quick-settling step of preparing a quick-settling powder using the first quick-setting fine powder. Process separation step of preparing CA-based slag in a molten state; A dry slow cooling step of producing cooled slag by cooling the CA-based slag in an enclosed space without contact with moisture; A particle size screening step of classifying the cooled slag into slag exceeding the screening standard particle size and slag below the screening standard particle size according to the screening standard particle size; a coarse crushing step of crushing the slag exceeding the screening standard particle size to produce crushed slag; A magnetic sorting step of magnetically sorting the crushed slag into crushed Fe high content slag and crushed Fe low content slag, and magnetically sorting the slag below the sorting standard grain size into Fe high content slag and low Fe slag; The crushed Fe low-content slag was pulverized to prepare a first fine powder having a powder degree of 5,000 to 7,000 cm ² /g, and the Fe low-content slag among the slags below the screening standard particle size was pulverized to have a powder degree of 5,000 to 7,000 cm ² /g A first quick-quick fine powder and a second quick-quick fine powder manufacturing step to prepare from the second quick-quick fine powder of; and Consisting of, a quick-setting fine powder manufacturing step of preparing a quick-setting fine powder including the first quick-setting fine powder and the second quick-setting fine powder. Process separation step of preparing CA-based slag in a molten state; A dry slow cooling step of producing cooled slag by cooling the CA-based slag in an enclosed space without contact with moisture; A particle size screening step of classifying the cooled slag into slag exceeding the screening standard particle size and slag below the screening standard particle size according to the screening standard particle size; a coarse crushing step of crushing the slag exceeding the screening standard particle size to produce crushed slag; A magnetic sorting step of magnetically sorting the crushed slag into crushed Fe high content slag and crushed Fe low content slag, and magnetically sorting the slag below the sorting standard grain size into Fe high content slag and low Fe slag; The crushed Fe low-content slag was pulverized to prepare a first fine powder having a powder degree of 5,000 to 7,000 cm ² /g, and the Fe low-content slag among the slags below the screening standard particle size was pulverized to have a powder degree of 5,000 to 7,000 cm ² /g A first quick-quick fine powder and a second quick-quick fine powder manufacturing step to prepare from the second quick-quick fine powder of; and A method for producing a quick-setting cement composition comprising a step of preparing a cement composition comprising at least one selected from the first fine powder and the second fine powder and a setting retardant. The method of claim 8, The method for producing a quick-setting cement composition, characterized in that the setting retardant is at least one selected from tartaric acid, sodium citrate, gluconic acid and anhydrous citric acid.

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