KR100732540B1 - Preparation of steel refinery flux containing aluminum and fluorite - Google Patents

Abstract

The present invention relates to a method for producing a steelmaking flux in which the mini-mill refining slag is hatched, and the present method recovers and crushes the mini-mill refining slag generated in the mini-mill refining process and removes impurities such as iron oxide. And refining by mixing fluorspar powder, aluminum and a binder in the refined mini-mill refined slag, and the flux prepared in this way can remove oxides and sulfides at the same time. It is effective in refining molten steel that has a bad effect on the oxide.

Steelmaking, Flux, Slag, Aluminum, Fluorite

Description

Manufacturing method of flux for steelmaking containing aluminum and fluorite {Preparation of steel refinery flux containing aluminum and fluorite}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a state diagram showing the chemical composition of the calcium aluminate-based mini mill refining slag as the main component of the flux of the present invention on a CaO-SiO ₂ -Al ₂ O ₃ system.

2 is an X-ray diffraction pattern diagram of a calcium aluminate-based mini mill refined slag which is a main component of the present invention;

3 is a state diagram of the CaO-SiO ₂ -Al ₂ O ₃ system showing the optimum range of dehydration rate,

4 is a state diagram of the CaO-Al ₂ O ₃ system showing the melting point of the calcium aluminate compound,

Figure 5 shows the addition of the flux of the present invention containing mini-mil refined slag, fluorspar and metal aluminum in the melting point test of iron-containing dust, the change of the fluorspar dust at a constant metal aluminum content (fixed 3% by weight) in the flux Graph showing melting point change,

Figure 6 shows the addition of the flux of the present invention containing mini-mil refined slag, fluorite and metal aluminum in the melting point test of iron-containing dust, the change of the iron-containing dust according to the change in the fluorite content at a constant metal aluminum content (fixed by 7% by weight) of the flux Graph showing melting point change,

Figure 7 shows the melting of iron-containing dust according to the change in the fluorspar content at a fixed metal aluminum content (fixed 15% by weight) in the flux of the iron-containing dust containing the flux of the present invention containing mini-mil refined slag, fluorite and metal aluminum Graph showing melting point change,

Fig. 8 shows the change in fluorspar content at a constant metal aluminum content (fixed at 3% by weight) in flux in the dehydration rate and slag flow test of the iron-containing dust containing flux of the present invention containing fine milled slag, fluorspar and metal aluminum. Graph showing the dehydration rate and slag flow of iron-containing dust according to

Fig. 9 shows the change in fluorspar content at a constant metal aluminum content (fixed at 7% by weight) in the flux in the dehydration rate and slag flow test of the iron-containing dust containing flux of the present invention containing mini-mil refined slag, fluorite and metal aluminum. Graph showing the dehydration rate and slag flow of iron-containing dust according to

FIG. 10 shows the change in fluorite content at a constant metal aluminum content (fixed to 15% by weight) in flux in the dehydration rate and slag flow test of the iron-containing dust containing flux of the present invention containing fine milled slag, fluorite and metal aluminum. Graph showing the dehydration rate and slag flow of iron-containing dust according to

The present invention relates to a method for producing a steelmaking flux in which the calcium aluminate-based minimill refining slag generated during the refining process of the minimill steelmaking process is hatched.

In the steelmaking process, slag generally removes impurities from the steel, forms a film between the molten steel and the atmosphere, reduces heat loss, and recombines the refined steel with O, N, and H in the atmosphere. It serves to prevent.

Non-metallic inclusions (O, S, P, etc.) contained in steel deteriorate the properties of steel. Especially, oxides and sulfides greatly deteriorate the properties of steel. Therefore, the removal of these impurities is essential in steelmaking processes such as electric furnaces and converters. . Quicklime (CaO) is the most widely used desulfurization agent to remove impurities due to its excellent thermodynamic desulfurization limit and low price, but its high melting point (2,570 ℃) slows down the reaction rate and increases the desulfurization treatment time, slag As the furnace temperature must be maintained above the melting point (1,400 ° C.) of the steel for fluidity, there are problems such as an increase in steelmaking power consumption and a long operating time.

In addition, by adding metal aluminum to the CaO-SiO ₂ -Fe ₂ O ₃ -based slag including the harmful components FeO, SiO ₂ and the like to change the slag composition to the CaO-SiO ₂ -Al ₂ O ₃ system, If the slag is not changed to a composition having excellent impurity trapping ability by adding a suitable flux to the top slag, there is a limit to the removal of impurities by the slag. In other words, the top slag has a low melting point, good fluidity, low oxygen potential (Potential) and must satisfy all the conditions of the activity of impurities.

Usually, the method of improving the fluidity and desulfurization ability of slag is to adjust the composition of top slag to the area | region which has high desulfurization ability and low melting point. In the CaO-A1 ₂ O ₃ -SiO ₂ -based slag, the region having the highest desulfurization capacity is 50% by weight of CaO, SiO ₂ ≤ 10% by weight, and A1 ₂ 0 ₃ 30% by weight, and has a low melting point. The flowable slag has a composition of C ₁₂ A ₇ (12CaO.Al ₂ O ₃ ) in calcium aluminate as shown in FIG. 4, and the compound is composed of the slag region (ideal desulfurization slag region) having the largest desulfurization ability of FIG. 3. Matches.

In order to adjust the composition of the top slag to a region having high desulfurization ability, CaO and Al ₂ O ₃ should be added to the top slag appropriately. When CaO and Al ₂ O ₃ are added in the form of a mixture, not a compound, the CaO (melting point 2,570 ℃) ) And Al ₂ O ₃ (melting point 2,020 ° C.) have a high melting point, so much time is required to change the slag composition. Therefore, a calcium aluminate compound having a low melting point is added to change the composition of the top slag. Among the calcium aluminate compounds, the compounds mainly composed of C ₁₂ A ₇ (12CaO · Al ₂ O ₃ ; Ca ₁₂ Al ₁₄ O ₃₃ ) have low melting point, so that CaO and Al ₂ O ₃ easily dissolve into slag It adjusts the composition of slag to the area where the impurities are absorbed well and improves the cleanliness of molten steel in a short time.

CaO-Al ₂ O ₃ -based fluxes containing C ₁₂ A ₇ as a main composition are usually prepared by mixing calcined lime (CaO) with calcined bauxite at a suitable ratio, followed by calcining or electromelting and cooling.

As described above, the conventional C ₁₂ A ₇ -based flux mixes calcined limestone calcined limestone and calcined bauxite calcined bauxite at a suitable ratio after crushing, pulverizing and mixing, and then refires, melts and cools the desired particle size. As a product that is crushed and screened again, it is an expensive steelmaking flux that requires a large amount of energy to manufacture.

Therefore, there is an urgent need to develop a flux that can reduce cost and improve steel quality by replacing the expensive import flux.

It is an object of the present invention to provide a new steelmaking flux which can improve the quality of steel and which is low in manufacturing cost.

In the study of the present inventors for achieving the above object, among the steel mill slag generated in the mini mill steel mill, the mini mill refined slag, which is a ladle slag, is mainly composed of C ₁₂ A ₇ (12CaO.7Al in calcium aluminate). ₂ O ₃ ) phase was found, the mini-mill refined slag was recovered and cooled, crushed and crushed to a certain size to remove impurities such as iron oxide, and then produced by mixing with aluminum and fluorite flux. The present invention was completed by finding that oxides and sulfides can be removed at the same time, and thus, oxides, such as iron oxides, which are adversely affecting steelmaking operations and steel quality, are effective in refining many molten steels.

Therefore, according to the present invention, in the method for producing a steelmaking flux, the minimill refined slag generated in the minimill steelmaking process is transported to a dedicated yard for cooling, crushed to a size of 50 mm or less, and the crushed minimill refined slag is After milling to a size of 3 mm or less, the fine-mill refined slag, which is crushed and pulverized, is selected using a particle size sorter, and the fine mill refined slag includes removing impurities such as iron oxide from the selected mini mill refined slag. Purification step, and

Provided is a method for producing a flux composition comprising the steps of preparing a flux comprising mixing and compressing metal aluminum, fluorite powder, and a binder to a refined mini mill refined slag.

Hereinafter, the present invention will be described in more detail.

The general chemical composition of the mini mill refined slag used as a main component in the steelmaking flux of the present invention is 40 to 55% by weight of CaO, Al ₂ O ₃ 20-40 wt%, SiO ₂ 1-9 wt%, MgO 3-10 wt%, Fe ₂ O ₃ 1.5 wt%, TiO ₂ Less than 1.5% by weight, the remainder is composed of unavoidable impurities.

In CaO-Al ₂ O ₃ -SiO ₂ -based slag, the region having the highest desulfurization capacity is 50% by weight of CaO, SiO ₂ ≤10% by weight, and 30% by weight of Al ₂ O ₃ , as shown in FIG. 3, and the melting point is low. The composition of the CaO-Al ₂ O ₃ compound having good fluidity is C ₁₂ A ₇ (12CaO.7Al ₂ O ₃ ) phase of calcium aluminate as shown in FIG. 4, and the compound has the highest desulfurization ability of FIG. 3. Area (abnormal desulfurization slag area).

Currently, among the steel mill slag generated in the mini mill steel mill of POSCO Gwangyang Works, the mini mill refining slag is mainly composed of calcium aluminate, as shown in the XRD pattern diagram of FIG. 2. The same effect as the expensive CaO-Al ₂ O ₃ (C ₁₂ A ₇ ) -based flux can be expected in the C ₁₂ A ₇ (12CaO · 7Al ₂ O ₃ ) phase.

Chemical composition analysis of mini-mill refined slag, which is the main component of the steelmaking flux of the present invention, and CaO-Al ₂ O ₃ (C ₁₂ A ₇ ) -based fluxes by manufacturers of each country are shown in Table 1. In Table 1, the unit of each chemical component analysis value is weight%, and the mini mill refining slag is a mini mill refining slag, which is the main component of the flux of the present invention, and is a mini mill refining slag among steel mill slags generated at the mini mill steel mill of POSCO Gwangyang Works. Flux is CaO-Al ₂ O ₃ (C ₁₂ A ₇ ) flux by manufacturer.

division CaO Al ₂ O ₃ SiO ₂ Manufacturer (nationality) Mini Mill Refined Slag 50 36 2.1 Imported flux CAF Less than 20 50 or more - Shidldally (US) LDSF 49-54 41-45 Less than 3.7 Lafarge company (France) AlumiCa 30-35 50-55 2 ~ 7 Alumica (USA) Syn. Slag 43 ~ 47 40-46 2 ~ 4 BPI (US)

The steelmaking flux of the present invention contains refined mini mill refined slag, metal aluminum, fluorite powder and a conventional binder.

The refined mini mill refining slag, which is a main component of the steelmaking flux of the present invention, recovers and crushes the mini mill refining slag generated in the mini mill steelmaking process, for example, and removes impurities such as iron oxide by, for example, magnetic separation. You can prepare. If the flux is manufactured from mini-mill refined slag containing impurities without removing impurities such as iron oxide, iron oxide is coated on the furnace wall refractory when iron oxide contained in the steelmaking flux is not reduced in the steelmaking furnace. It causes problems in the steelmaking industry, and the specific gravity of the steelmaking flux changes frequently according to the degree of incorporation of impurities, making it difficult to quantitatively add correction components, and the standard input ratio of the flux changes frequently during the steelmaking operation. It is desirable to remove impurities such as

The metal aluminum compounded in the steelmaking flux of the present invention is added for component correction to increase the removal efficiency of oxides and sulfides, and the mixing ratio of the metal aluminum in the slag mixture constituting the flux is 1 to 15% by weight. More preferably, it is 3-15 weight%. In the present steelmaking flux composition, the higher the addition ratio of the metal aluminum, the lower the shrinkage point, especially the melting point, but the higher the melting end point. This is because the higher the addition ratio of the metal aluminum added to the steelmaking flux, the more the metal aluminum component is in the steelmaking flux, and as the metal aluminum starts to melt at low temperature, the temperature of the shrinkage point is lowered, but the impurities contained in the metal aluminum. Therefore, until the complete dissolution, the higher the addition ratio of metal aluminum, the higher the temperature. Through the melting test, the shrinkage point, which is the initial melting point, was drastically lowered until the addition ratio of the metal mill blended with the mini mill refined slag was 15% by weight. However, when the addition ratio of the metal aluminum exceeds 15% by weight, the shrinkage point, which is the initial melting point, decreased. Gradually slow, but rather higher melting end point. In addition, when the mixing ratio of the metal aluminum is less than 1% by weight, the effect of improving the oxide and sulfide removal efficiency is insufficient. The most effective addition ratio of metallic aluminum added to the steelmaking flux is 3 to 15% by weight in the slag mixture.

The fluorspar powder blended in the steelmaking flux composition of the present invention serves to further improve the flowability and desulfurization ability of the top slag. In the flux composition of the present invention, the fluorite powder is added in an amount of 1 to 30% by weight, more preferably 3 to 30% by weight in the slag mixture. The greater the amount of slag, the more the liquidity of the top slag can be reliably improved in a short time.However, the loss of refractory due to the addition of fluorspar powder and the generation of hydrogen fluoride gas (HF Gas) during operation, as well as those contained in the furnace slag It is preferable to reduce the amount of fluorite added to the slag mixture by less than 30% by weight in the slag mixture because there is a problem such as dissolution of fluorine component. In addition, if the mixing ratio of the fluorspar powder is too small, especially less than 1% by weight, the effect of improving the fluidity of the top slag is insufficient, it is preferable to use the forming powder within the above range. Mixing of the refined mini mill refined slag and fluorite powder is preferably carried out at a particle size of 3 mm or less.

In the steelmaking flux of the present invention, the binder is blended to form a flux having a predetermined shape by combining slag and formation, and a binder commonly used in steelmaking flux may be used. Representative examples of such conventional binders include molasses and liquid sodium silicate.

The amount of the binder used in the steelmaking flux of the present invention is changed depending on the amount of slag to be bonded or, if necessary, the total amount of slag and fluorspar powder, and is not particularly limited because it is an amount sufficient to be fluxed by compression molding. 1 to 35 parts by weight is usually suitable for 100 parts by weight of the slag mixture.

Hereinafter, an example of the steelmaking flux manufacturing method according to the present invention will be described.

Steelmaking flux of the present invention can be produced through the mini-mill refined slag purification step, flux composition and molding step.

For example, the refining step of the mini mill refining slag is carried by cooling the mini mill refining slag generated in the mini mill steelmaking process to a dedicated yard, and 50 mm using crushing equipment such as jaw crusher or cone crusher. The crushed mini mill refining slag was crushed to the size of 3 mm or less by using a grinding machine such as a hammer mill or roller mill, and then crushed and milled. The slag is selected using a particle size sorter with a size of 3 mm or less and a fine mill refining slag of more than 3 mm, and the selected mini mill refining slag of 3 mm or less is subjected to a magnetic separator and impurities such as iron oxide contained in the mini mill refining slag. Consists of removing it. At this time, in order to cool the mini-mill refined slag, an air cooling method of slow cooling in air without spraying to minimize moisture is suitable. Minimil refined slag of more than 3 mm in size can also be regrind in subsequent flux production. Here, the reason for grinding the fine mill refined slag to 3 mm or less is that impurities such as iron oxide are easily removed in a subsequent impurity removal step, and the mixture of the mini mill refined slag, metal aluminum, fluorite powder, and a binder is different in particle size during the transfer process. This is to prevent classification by each other.

In the flux composition and forming step, a fine mill refined slag of less than 3 mm in which impurities are removed, a metal aluminum and fluorspar powder for component correction, and a binder for flux molding are mixed in a mixer, and the resulting mixture is mixed to a certain size. After compression molding in the furnace, and transported to the particle size separator, the particle size separator having a particle size of 10 mm or more is separated and recovered to obtain a steelmaking flux. 10 mm or less can then be recompressed in subsequent flux production. Compression molding of the slag mixture is carried out to about 50 mm using a compression molding machine. An example of such a compression molding machine is a briquetting machine, which is compression molded in the form of briquettes.

Features and other advantages of the present invention as described above will become more apparent from the following examples. However, the present invention is not limited to the following examples.

EXAMPLES 1-7

Mini mill refined slag generated from mini mill steel mill of POSCO Gwangyang Works is transported to a dedicated yard and cooled by air, and the cooled slag is shredded to a size of 50mm or less after using the hammer mill. To a size of 3mm or less. The pulverized slag was sieved in a vibrating separator having a sieve having a mesh hole of 3 mm inside to obtain slag powder of 3 mm or less, which was then transferred to a magnetic separator to separate and remove impurities such as iron oxide.

4.33 parts by weight of a slag mixture containing a fine-mill refined slag from which impurities are removed at a ratio as shown in Table 2 below, a metallic aluminum having a particle size of 3 mm or less, and a fluorite powder having a particle size of 3 mm or less (85 wt% or more of CaF ₂ ) (100 weight of iron dust) (Parts by weight), a commercially available molasses (Molasses) stock solution commonly used as a binder for the preparation of the flux is mixed with a weight part (based on 100 parts by weight of iron dust) as shown in Table 2, and mixed in a mixer for a predetermined time. After the mixture was put into a briquetting machine and compression molded, a briquette having a particle size of 10 mm or more was recovered to prepare a steelmaking plus.

4.33 parts by weight of flux (excluding the binder content) is added to a chamber electric furnace using Super Kanthal with respect to 100 parts by weight of iron-containing dust of about 1 mm in particle size, which is an electric furnace slag crushed product. Melting Point was measured while heating at a rate of min ± 1 ° C / min. In Table 1, the shrinkage point of the melting point is the temperature at which the sample shrinks and the first visible visible crack occurs in the sample, and the melting point of the melting point is the temperature at which the collapsed sample collapses and starts to liquefy. The melting end point of the melting point is the temperature at which the solid sample remaining in the liquefied sample is completely liquefied and is the end point of the melting point.

In addition, 4.33 parts by weight of flux (excluding the binder content) was added to a chamber electric furnace using Super Kanthal with respect to 100 parts by weight of iron-containing dust of about 1 mm in particle size, which is an electric furnace slag crushed product. After heating up at a rate of min ± 1 ° C./min, the rate of dehydration and slag flow were measured. The withdrawal rate and slag fluidity measurement results for each example are shown in Table 2. The discharge rate was calculated as ([% S] o-[% S]) ÷ [% S] o × 100 (%) (where [% S] is the weight% of sulfur in molten steel after operation, [% S] o Is the weight% of sulfur in raw materials before operation), slag fluidity is the ratio of iron content in the slag (wt%) when slag is excluded from the furnace.

division Dust (parts by weight) Slag mixture (% by weight) Binder (parts by weight) Melting Point (℃)  Discharge rate (%) Slag fluidity (%) Mini Mill fluorite Al Shrink point Decay point Melting end point    Example CA 1 100 94 3 3 0.39 1400 1440 1470 58.27 4.44 CA 2 100 92 5 3 0.40 1390 1430 1460 48.52 4.37 CA 3 100 86 7 7 0.43 1370 1415 1450 56.95 4.27 CA 4 100 84 9 7 0.43 1375 1430 1450 48.81 4.00 CA 5 100 82 11 7 0.44 1370 1410 1440 74.15 3.53 CA 6 100 80 13 7 0.45 1380 1405 1430 64.24 3.17 CA 7 100 78 15 7 0.45 1380 1405 1430 60.48 3.00 CA 8 100 71 22 7 0.46 1370 1400 1420 57.79 2.97 CA 9 100 63 30 7 0.47 1370 1400 1420 49.18 2.95 CA 10 100 82 3 15 0.46 1415 1450 1480 49.43 4.53 CA 11 100 80 5 15 0.47 1395 1435 1470 57.15 4.47 CA 12 100 78 7 15 0.47 1385 1435 1460 49.80 4.20 CA 13 100 76 9 15 0.48 1380 1435 1450 54.90 3.83 CA 14 100 74 11 15 0.48 1375 1415 1440 76.62 3.46 CA 15 100 72 13 15 0.49 1385 1410 1430 67.02 3.19 CA 16 100 70 15 15 0.50 1385 1410 1430 61.63 2.93 CA 17 100 63 22 15 0.51 1375 1400 1420 58.37 2.89 CA 18 100 55 30 15 0.52 1375 1400 1420 50.46 2.86

Comparative Example 1

Melting point of the iron-containing dust was measured in the same manner as in Example 1. The measurement results are shown in Table 3.

Comparative Example 2

Except for the use of flux-molded flux by mixing 4.33 parts by weight of CaO-A _l2 O ₃ (C ₁₂ A ₇ ) and 0.16 parts by weight of binder, which are currently imported and used with a particle size of about 10 mm by weight of iron-containing dust. The same procedure was repeated to determine the melting point, flow rate and slag flow. The measurement results are shown in Table 3.

division Dust (parts by weight) CaO-A _l2 O ₃ (parts by weight) Binder (parts by weight) Melting Point (℃) Discharge rate (%) Slag fluidity (%) Shrink point Decay point Melting end point Comparative Example 1 Ref.1 100 0 0 1385 1455 1530 - - Comparative Example 2 Ref.2 100 4.33 0.16 1395 1460 1510 37.58 5.19

[evaluation]

As a result of melting point experiments by addition ratios of fluxes, such as fluxes, which were formed by compression of slag mixtures composed mainly of mini-mill refined slag, as shown in Tables 2 and 3, the melting point, flux ratio, and slag fluidity of the fluxes of Examples and Comparative Examples 2 It was confirmed that the following features.

The melting end point of the Example was 40-110 degreeC lower than the comparative example 1 and the comparative example 2. In the case of Comparative Example 1 and Comparative Example 2, in particular, the temperature from the shrinkage point to the melting end point was 115 ° C to 145 ° C.

In Examples, melting started at a temperature about 10 ° C. lower than Comparative Example 2 and completely liquefied when the temperature was raised to about 60 ° C. That is, the embodiment using the flux according to the present invention improves the fluidity and composition of the top slag more quickly as the melting point is low and completely liquefied in a short time, and the low-temperature desulfurization by the rapid reaction to maximize the flow rate per unit time Able to know.

As shown in Tables 2 to 3 and FIGS. 5 to 7, the higher the addition ratio of fluorspar in the slag mixture in the steelmaking flux of the example, the lower the melting point. As a result of experimenting up to 30% by weight of fluorspar in the slag mixture, the melting point was lowered as the fluorspar was added. For this reason, the amount of fluorspar added to the slag mixture should be minimized as much as possible. Through melting test, it was confirmed that the most effective ratio to lower the melting point while minimizing the addition ratio of fluorspar was 3 to 30% by weight.

As shown in Tables 2 to 3 and FIGS. 5 to 7, the steel flux of the embodiment is higher the addition ratio of the metal aluminum, the lower the shrinkage point and the melting end point than when only fluorite is added alone. This is because the higher the addition ratio of the metal aluminum added to the steelmaking flux of the embodiment, the more aluminum components in the steelmaking flux, the lower the temperature of the shrinkage point as the metal aluminum first starts to melt at low temperatures, and also affects the melting end point. Because of this, the melting point was lowered. The melting point test shows that the shrinkage point, which is the initial melting point, is lowered up to 15% by weight of the metal aluminum in the slag mixture, and the most effective addition ratio of the metal aluminum added to the steelmaking flux of the embodiment is based on the slag mixture 3 to 15% by weight was confirmed.

In particular, the steelmaking flux of the embodiment in which the metal aluminum is added can remove oxides and sulfides at the same time, and is effective in refining molten steel having many oxides, such as iron oxide, which adversely affects steelmaking and steel quality.

The deflow rate and slag fluidity of the examples using the flux of the present invention were superior to those of the comparative example 2 using the imported flux. That is, when the flux of the present invention is added, as the melting point is lower than that of Comparative Example 2 and liquefied in a short time, the flowability and composition of the top slag are more rapidly improved, and low-temperature desulfurization by rapid reaction is possible, thereby maximizing the deflow rate per unit time. You can.

As shown in Tables 2 to 3 and Figures 8 to 10, the flux of the embodiment is higher the addition ratio of fluorspar, the higher the discharge rate and the lower the slag fluidity. As a result of experimenting up to 30% by weight of fluorspar, the dehydration rate was higher than that of Comparative Example 2 regardless of the fluorspar addition rate up to 30% by weight of fluorspar, and slag fluidity was lowered up to 30% by weight of fluorspar. For the above reasons, the amount of fluorspar added to the slag mixture should be minimized as much as possible. The most effective addition ratio that can lower the melting point while minimizing the fluorspar addition ratio through the deflow rate and slag fluidity experiments is to increase the degassing rate and the slag fluidity. It was confirmed that the fluorspar addition ratio of the fall of 3 to 30% by weight.

As shown in Tables 2 to 3 and FIGS. 8 to 10, the steel flux of the embodiment showed a tendency that the higher the addition ratio of metal aluminum (Metal Al.), The higher the deflow rate and the lower the slag fluidity. This is because the higher the addition ratio of the metal aluminum (Metal Al.) Added to the steelmaking flux of the embodiment, the more metal aluminum components are added to the steelmaking flux, and as the metal aluminum begins to melt at low temperatures, the temperature of the shrinkage point is lowered. This is because the melting point is lowered by affecting the melting end point. The melting point test showed that the degassing rate increased up to 15% by weight of the metal aluminum in the slag mixture and the slag flowability was lowered. Thus, the most effective addition ratio of the metal aluminum added to the steelmaking flux of the embodiment was 3 It could be confirmed that it is ~ 15% by weight (excluding the binder).

 In particular, the steelmaking flux of the embodiment in which the metal aluminum is added can remove oxides and sulfides at the same time, and is effective in refining molten steel with high oxides, such as iron oxide, which adversely affects steelmaking operations and steel quality.

As described above, the steelmaking flux of the present invention is a high value-added steelmaking flux that can replace the conventional expensive imported CaO-Al ₂ O ₃ (C ₁₂ A ₇ ) -based flux using calcium aluminate-based mini mill refined slag. In addition to import substitution, steelmakers can reduce costs and improve quality, and by adding metal aluminum to the mini mill refining slag to correct the components, low-temperature desulfurization can be achieved by rapid reaction, maximizing the deflow rate per unit time. It is an industrially useful invention as a steelmaking flux that can smoothly remove impurities in molten steel to improve the quality of steel.

Claims (3)

In the method for manufacturing the steelmaking flux, the minimill refined slag generated in the minimill steelmaking process is transported to a dedicated yard for cooling, crushed to a size of 50 mm or less, and the crushed minimill refined slag to a size of 3 mm or less. After grinding, the step of refining the mini-mill refined slag comprising the step of screening the crushed mini-mill refined slag with a particle size separator and removing impurities such as iron oxide in the selected mini mill refined slag, and 55 to 98% by weight of refined mini-mill refined slag is mixed with 1 to 15% by weight of metal aluminum, 1 to 30% by weight of fluorite powder (CaF ₂ content of 85% by weight or more) and an appropriate amount of binder, and compression molding is carried out by conventional compression molding means. Flux manufacturing method for steelmaking comprising the flux manufacturing step comprising a. delete The method of claim 1, wherein the content of the metal aluminum is 3 to 15% by weight, the content of fluorspar powder is 3 to 30% by weight flux manufacturing method for steelmaking.

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