Flux and method for operating holding furnace

Abstract

An embodiment of the present invention relates to a flux that can be introduced into an internal space of a holding furnace capable of accommodating high-manganese molten metal. The flux may comprise 46 wt% to 56 wt% of calcium oxide, 9 wt% to 14 wt% of silicon oxide, 4 wt% to 8 wt% of magnesium oxide, and 23 wt% to 31 wt% of aluminum oxide on the basis of 100 wt% of the flux Therefore, according to embodiments of the present invention, the melting point of the slag accommodated in the holding furnace can be lowered, and the basicity can be adjusted. In addition, the flux can modify the component composition of the slag such that reactivity with refractories constituting the holding furnace is reduced or prevented. Accordingly, it is possible to suppress or prevent the tap hole of the holding furnace from being blocked by the slag having a high melting point or the inner wall of the holding furnace formed of refractories from being eroded by the slag. Therefore, the service life of the holding furnace can be extended, and the operability of the holding furnace can be improved.

Description

Operation method of flux and holding furnace

[0001] The present invention relates to a flux and a method for operating a holding furnace, and more specifically, to a flux and a method for operating a holding furnace capable of accommodating a high-manganese molten metal and improving the operability of the holding furnace.

[0002] Generally, high-manganese steel contains 1% to 30% by weight of manganese (Mn), and among the types of high-manganese steel are high-performance steels such as Twinning Induced Plasticity (TWIP) steel containing 15% to 30% by weight of manganese.

[0003] The manufacturing method of high-manganese steel is briefly explained below. Molten iron produced in a blast furnace is refined in a converter to produce molten steel. Meanwhile, a molten metal containing a high content of manganese (Mn) (hereinafter referred to as "high-manganese molten metal") is prepared, and the prepared high-manganese molten metal is introduced into a holding furnace for storage. That is, the cover of the holding furnace is separated from the container to open the container, and the high-manganese molten metal is charged into the internal space of the container. Then, the temperature of the holding furnace is maintained at a predetermined temperature to keep the high-manganese molten metal warm. Next, the molten steel and the high-manganese molten metal are combined to produce molten steel containing a high content of manganese (hereinafter referred to as "high-manganese molten steel"). That is, the tap port of the holding furnace container is opened to discharge the high-manganese molten metal to the outside and combine it with the molten steel.

[0004] In order to charge high-manganese molten metal into the internal space of the holding furnace, the vessel must be opened. Additionally, in order to discharge (tap) the high-manganese molten metal from the internal space of the holding furnace to the outside, the tap port formed in the vessel must be opened. Consequently, when charging high-manganese molten metal into the holding furnace or discharging it from the holding furnace, the atmosphere inevitably flows into the internal space of the holding furnace. Therefore, the composition of the slag floating on the surface of the high-manganese molten metal changes, and as a result, the melting point of the slag increases. In other words, high-melting-point slag is formed. High-melting-point slag adheres to the inner wall of the holding furnace vessel and causes the tap port to close. Therefore, it is necessary to lower the melting point of the slag contained in the holding furnace, and to do this, the composition of the slag must be changed.

[0005] However, if the composition of the slag is altered, the inner wall of the refractory furnace is damaged by the slag. In other words, the reaction between the slag and the inner wall of the furnace causes damage to the wall, which leads to a problem of shortened furnace lifespan.

[0006] (Prior Art) (Patent Document 1) Korean Registered Patent 10-1439763

[0007] The present invention provides a flux and a method for operating a holding furnace that can improve the operability of a holding furnace capable of accommodating a high-manganese molten metal.

[0008] The present invention provides a flux and a method for operating a holding furnace capable of suppressing or preventing the closure of the tapping port of a holding furnace capable of accommodating high-manganese molten metal and the erosion of the holding furnace.

[0009] An embodiment of the present invention is a flux that can be introduced into the internal space of a holding furnace capable of accommodating a high-manganese molten metal, wherein, with respect to 100 weight% of the flux, calcium oxide is 46 weight% to 56 weight%, silicon oxide is 9 weight% to 14 weight%, magnesium oxide is 4 weight% to 8 weight%, and aluminum oxide is 23 weight% to 31 weight%.

[0010] The flux according to an embodiment of the present invention may contain iron oxide in an amount of 0% or more and 5% or less with respect to 100% by weight of the flux.

[0011]

[0012] An embodiment of the present invention may include a method for operating a holding furnace capable of holding high-manganese molten metal, the method comprising: a process of opening the opening of the holding furnace to charge high-manganese molten metal into the internal space of the holding furnace; and a process of introducing a flux into the internal space of the holding furnace, wherein the flux comprises 46% to 56% by weight of calcium oxide, 9% to 14% by weight of silicon oxide, 4% to 8% by weight of magnesium oxide, and 23% to 31% by weight of aluminum oxide, based on 100% by weight of the flux.

[0013] The above flux may contain iron oxide in an amount of 0% or more and 5% or less with respect to 100% by weight of the above flux.

[0014] A method for operating a holding furnace according to an embodiment of the present invention may include a process of producing a second slag by reacting a first slag floating on the surface of a high-manganese molten metal contained in the internal space of the holding furnace with a flux introduced into the interior of the holding furnace.

[0015] A method for operating a holding furnace according to an embodiment of the present invention may include a process of controlling the temperature of the internal space of the holding furnace while the molten high-manganese metal is contained in the internal space of the holding furnace, thereby maintaining the temperature of the molten high-manganese metal contained in the internal space of the holding furnace at 1400℃ to 1500℃.

[0016] A method for operating a holding furnace according to an embodiment of the present invention comprises: a process of closing the opening of the holding furnace after the process of introducing the flux is completed; a process of opening the tapping port of the holding furnace to discharge the high-manganese molten metal contained in the internal space of the holding furnace through the tapping port; and a process of closing the tapping port after the discharge is completed; wherein, in at least one of the process of charging the high-manganese molten metal into the internal space of the holding furnace and the process of discharging, air is introduced into the internal space of the holding furnace, thereby increasing the content of manganese oxide contained in the second slag.

[0017] The basicity of the second slag with increased manganese oxide content may be 1.0 or higher.

[0018] The melting point of the second slag with increased manganese oxide content may be 1350°C to 1500°C.

[0019] The flux according to the embodiments of the present invention can lower the melting point of slag contained in a holding furnace and control the basicity. In addition, the flux can change the composition of the slag so that it has low reactivity with or does not react with the refractory material constituting the holding furnace.

[0020] Therefore, it is possible to suppress or prevent the tapping port of the holding furnace from being blocked by high-melting-point slag, or the inner wall of the holding furnace formed of refractory material from being eroded by slag. Consequently, the lifespan of the holding furnace can be extended, and the operability of the holding furnace can be improved.

[0021] Figure 1 is a drawing illustrating a holding furnace capable of accommodating high-manganese molten metal.

[0022] Figure 2(a) is a diagram showing the state of high-manganese molten metal being charged into a holding furnace.

[0023] Figure 2(b) is a diagram showing the state of flux being introduced into the holding furnace.

[0024] Figure 2(c) is a drawing showing the container and tapping port of the heat retention furnace in a closed state.

[0025] Figure 2 (d) is a diagram illustrating the state of discharging high-manganese molten metal contained in a holding furnace.

[0026] FIG. 3 is a ternary phase diagram of calcium oxide (CaO), aluminum oxide (Al2O3), and manganese oxide (MnO) of the second slag according to Comparative Examples 13 to 15.

[0027] Figure 4 is an experimental apparatus for testing the reactivity of slag and refractory material.

[0028] Figure 5 is a photograph of a specimen before the experiment, a specimen after the experiment using slag according to Comparative Example 15, and a specimen after the experiment using slag according to Comparative Example 25.

[0029] FIG. 6 is a ternary phase diagram of calcium oxide (CaO), aluminum oxide (Al2O3), and manganese oxide (MnO) of the second slag according to Comparative Examples 21 to 24 and Example 2.

[0030] Figure 7 is a photograph of a specimen before the experiment, a specimen after the experiment using slag according to Example 2, a specimen after the experiment using slag according to Example 3, and a specimen after the experiment using slag according to Example 4.

[0031] FIG. 8 is a graph showing the melting point of the second slag according to the content of the flux according to Example 1 for 100 weight% of the second slag.

[0032] Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms, and these embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. The drawings may be exaggerated to illustrate embodiments of the present invention.

[0033]

[0034] The present invention relates to a method for maintaining the temperature of flux and high-manganese molten metal, and more specifically, to a method for maintaining the temperature of flux and high-manganese molten metal that can improve the operability of a holding furnace capable of accommodating high-manganese molten metal. Even more specifically, the present invention relates to a method for maintaining the temperature of flux and high-manganese molten metal that can suppress or prevent the closure of the tapping port of a holding furnace capable of accommodating high-manganese molten metal and the erosion of the holding furnace.

[0035] The high-manganese molten metal may have a manganese (Mn) content of 70% by weight or more and less than 100% by weight with respect to 100% by weight of the high-manganese molten metal. More specifically, the high-manganese molten metal may have a manganese (Mn) content of 70% by weight or more and less than 99.5% by weight with respect to 100% by weight of the high-manganese molten metal.

[0036] The following describes a general method for manufacturing a high-manganese molten metal. First, a manganese-containing ferroalloy (hereinafter referred to as manganese ferroalloy) is prepared. The manganese ferroalloy may be, for example, Fe-Mn. Then, the prepared manganese ferroalloy is introduced into a melting furnace and melted. In this way, a molten metal containing a high amount of manganese (high-manganese molten metal) can be produced. That is, a high-manganese molten metal can be produced in which the manganese (Mn) content is 70% by weight or more and less than 100% by weight with respect to 100% by weight of the total. Next, the high-manganese molten metal is introduced into a holding furnace. Before introducing the high-manganese molten metal into the holding furnace, refining such as dephosphorization may be performed on the high-manganese molten metal, and known methods may be applied as necessary.

[0037] The molten high-manganese metal charged into the holding furnace can be held or maintained at a temperature of 1400°C to 1500°C. That is, the holding furnace can maintain and store the molten high-manganese metal at a temperature of 1400°C to 1500°C. In addition, the holding furnace can stir the molten high-manganese metal by supplying an inert gas such as argon (Ar) from the bottom (bottom blowing). The process of charging the molten high-manganese metal into the holding furnace can be carried out in multiple steps.

[0038] To manufacture high-manganese steel, it is necessary to produce molten steel (high-manganese molten steel) containing a high manganese content. To this end, molten iron produced in a blast furnace is refined to produce molten steel, and the high-manganese molten metal is mixed with the molten steel. That is, the high-manganese molten metal, which has been stored in a holding furnace, is discharged into a container holding the molten steel to mix the high-manganese molten metal with the molten steel. In this way, high-manganese molten steel can be produced. Then, the high-manganese molten steel is transferred to a casting device, and high-manganese steel can be manufactured by performing casting in the casting device.

[0039]

[0040] FIG. 1 is a drawing illustrating a holding furnace capable of receiving high-manganese molten metal. FIG. 2(a) is a drawing illustrating the state of charging high-manganese molten metal into the holding furnace. FIG. 2(b) is a drawing illustrating the state of introducing flux into the holding furnace. FIG. 2(c) is a drawing illustrating the state in which the vessel and tapping port of the holding furnace are closed. FIG. 2(d) is a drawing illustrating the state in which the high-manganese molten metal received in the holding furnace is being discharged.

[0041] Referring to FIG. 1, the holding furnace (100) may include a container (110) having an internal space (111) capable of receiving high-manganese molten metal (M) and a discharge port (113) capable of discharging the high-manganese molten metal (M), a heating unit (120) installed in the container (110) to heat the container (110), a container cover (130) capable of closing or opening the opening (112) of the container (110), and a discharge port cover (140) capable of closing or opening the discharge port (113). Additionally, the holding furnace (100) may include a nozzle (150) formed by penetrating the bottom of the container (110) in an upward or downward direction to supply gas into the internal space (111) of the container (110).

[0042] The container (110) may have a tubular shape with an open top. That is, an opening (hereinafter, upper opening (112)) may be formed at the top of the container (110), and high-manganese molten metal (M) may flow into the internal space (111) through the upper opening (112) (see FIG. 2 (a)).

[0043] The container (110) may include an outer member (110a) having an internal space and an open top, and an inner member (110b) connected to the inner wall of the outer member (110a) and having an open top.

[0044] The outer member (110a) may be formed from a material including metal, for example, the outer member (110a) may be an iron shell. The inner member (110b) may be installed along the inner surface of the outer member (110a). The inner member (110b) may be formed from a material including refractory material, and more specifically, may be formed from a material including magnesia and aluminum oxide. More specifically, the inner member (110b) may be formed from a material including magnesium aluminate spinel (MgAl2O4). Accordingly, the inner member (110b) including magnesium aluminate spinel (MgAl2O4) may be neutral or basic.

[0045] A discharge port (113) is formed at the top of the container (110) to allow high-manganese molten metal (M) to be discharged. That is, a discharge port (113) may be formed on one side of the top of the container (110). More specifically, the discharge port (113) may have a shape that extends outward from the top of the container (110), and the discharge port (113) may be connected to the upper opening (112).

[0046] The heating unit (120) may be installed on the outer surface of the inner member (110b). That is, the heating unit (120) may be embedded or inserted into the inner side of the outer member (110a) so as to be positioned on the outer surface of the inner member (110b). The heating unit (120) may include a coil, and the coil may be inserted into the inner side of the outer member (110a). At this time, the coil may be inserted into the inner side of the outer member (110a) so as to extend in the circumferential direction and the vertical direction of the inner member (110b). The coil may be connected to a power supply unit (not shown), and when power is supplied, heat may be generated from the coil. Accordingly, the container (110) may be heated, and as a result, the molten high-manganese metal contained in the internal space of the container (110) may be heated and maintained at a temperature of 1400°C to 1500°C.

[0047] The heating unit (120) is not limited to the example described above, and various means capable of heating the container (110) or the high-manganese molten metal (M) may be applied.

[0048] The container cover (130) can close or open the upper opening (112) of the container (110). The container cover (130) may have a size such that it closes the container cover (130) of the container (110) but does not close the spout (113). For example, one side of the container cover (130) may be supported on the top of the container (110) as shown in (c) of FIGS. 1 and 2, thereby closing the upper opening (112) of the container (110). Additionally, if one side of the container (110) is separated from the top of the container (110), the upper opening (112) of the container (110) may be opened as shown in (a) and (b) of FIGS. 2.

[0049] The spout cover (140) can close or open the spout (113), and the spout cover (140) may be smaller in size than the container cover (130). For example, as shown in (a), (b), and (c) of FIGS. 1 and 2, at least a portion of the spout cover (140) may be inserted into the spout (113), thereby closing the spout (113). Additionally, as shown in (d) of FIGS. 2, if the spout cover (140) is removed from the spout, the spout (113) may be opened.

[0050]

[0051] When the high-manganese molten metal (M) is produced, it must be maintained at a predetermined temperature until it is used. Accordingly, when the high-manganese molten metal (M) is produced, the high-manganese molten metal (M) is loaded into a holding furnace (100) for storage or preservation. That is, as shown in (a) of FIG. 2, the container cover (110) of the holding furnace (100) is separated from the container (110) to open the upper opening (112) of the container (110), and then the high-manganese molten metal (M) is loaded into the internal space (111) of the container (110). Afterward, as shown in (c) of FIG. 1 and FIG. 2, the upper opening (112) of the container (110) is closed using the container cover (130). Then, the heating unit (120) is operated to heat the container (110) and maintain the molten high-manganese (M) at a temperature of 1400°C to 1500°C. In addition, an inert gas, such as argon (Ar) gas, is supplied through the nozzle (150) to stir the molten high-manganese (M).

[0052] Meanwhile, the manufactured high-manganese molten metal can first be placed in a ladle, and the high-manganese molten metal (M) placed in the ladle can be charged into a holding furnace (100). Slag may be floating on the upper surface (hereinafter, molten metal surface) of the high-manganese molten metal (M) placed in the ladle, and this slag may have been generated during the refining process of manufacturing the high-manganese molten metal (M). When charging the high-manganese molten metal (M) placed in the ladle into the holding furnace (100), the inflow of slag into the holding furnace (100) is minimized. However, since it is difficult to completely block the inflow of slag, a small amount of slag may flow into the holding furnace (100). Accordingly, as shown in FIG. 1, slag (S) may be floating on the molten metal surface of the high-manganese molten metal (M). At this time, since a small amount of slag has been introduced into the holding furnace (100), slag (S) may float on some of the surface of the high-manganese molten metal (M). That is, some of the surface of the high-manganese molten metal (M) may be covered by slag (S), and the rest may be exposed.

[0053] In order to charge high-manganese molten metal (M) into the internal space of the holding furnace (100) or to discharge the high-manganese molten metal (M) inside the holding furnace (100) to the outside, the upper opening (112) and the tapping port (113) of the holding furnace (100) must be opened as shown in (a) and (d) of FIG. 2, and in this process, air may be introduced into the internal space of the holding furnace (100). Then, the content of manganese oxide (MnO) contained in the slag (S) may increase due to the air introduced into the internal space of the holding furnace (100). As a result, the melting point of the slag may increase, and the slag, which was in a liquid state, may become solid. Then, the solid slag may adhere to the inner member (110b) of the container (110), and as a result, the tapping port (113) may be closed by the solid slag.

[0054] Therefore, it is necessary to lower the melting point of the slag (S), and to do this, it is necessary to introduce flux into the holding furnace (100) as shown in (b) of FIG. 2. That is, flux (f) can be introduced into the holding furnace (100) after the high-manganese molten metal is introduced into the holding furnace (100). The process of introducing the high-manganese molten metal into the holding furnace (100) can be performed multiple times, and flux (f) can be introduced into the holding furnace each time the introduction of the high-manganese molten metal (M) is completed. Of course, this is not limited to this, and flux (f) can also be introduced after some of the introduction processes are completed during the introduction of the high-manganese molten metal (M) multiple times.

[0055] When flux is introduced into the holding furnace (100), the composition of the slag (S) changes, and the melting point may decrease. However, due to the change in the composition of the slag (S), the reactivity with the inner member (110b) formed of refractory material may increase. That is, the inner member of the holding furnace (100) may be eroded due to the slag (S) with a changed composition, and consequently, the lifespan of the holding furnace (100) may be shortened.

[0056] Therefore, a flux (f) capable of changing the composition of the slag (S) is required to reduce or suppress the reaction with the refractory material while lowering the melting point. Additionally, since the inner member (110b) formed from the refractory material is neutral or basic, it is desirable for the slag (S) to be basic. That is, in order for the reaction with the refractory material to be reduced or suppressed, the basicity of the slag (S) needs to be 1.0 or higher. Therefore, a flux capable of making the basicity 1.0 or higher is required.

[0057]

[0058] The flux (f) according to an embodiment of the present invention may be a flux that can be introduced into a holding furnace (100) capable of receiving a high-manganese molten metal (M) as shown in (b) of FIG. 2.

[0059] The flux (f) according to an embodiment of the present invention may include calcium oxide, silicon oxide, magnesium oxide, and aluminum oxide. Additionally, the flux according to an embodiment of the present invention may include impurities, and the impurities may include iron oxide. Furthermore, with respect to 100 weight% of the flux, the content of calcium oxide may be 46 weight% to 56 weight%, the content of silicon oxide may be 9 weight% to 14 weight%, the content of magnesium oxide may be 4 weight% to 8 weight%, the content of aluminum oxide may be 23 weight% to 31 weight%, and the content of iron oxide (Fe2O3) may be 5 weight% or less (0 weight% or more).

[0060] More specifically, with respect to 100 wt% of flux, the content of calcium oxide (CaO) may be 46 wt% to 56 wt%, the content of silicon oxide (SiO2) may be 9 wt% to 14 wt%, the content of magnesium oxide (MgO) may be 4 wt% to 8 wt%, and the content of aluminum oxide (Al2O3) may be 23 wt% to 31 wt%. In addition, with respect to 100 wt% of flux, the content of iron oxide (Fe2O3) may be 5 wt% or less (0 wt% or more). More preferably, the content of calcium oxide (CaO) per 100 wt% of flux may be 48 wt% to 52 wt%, the content of silicon oxide (SiO2) may be 12 wt% to 14 wt%, the content of magnesium oxide (MgO) may be 5.5 wt% to 6.5 wt%, the content of aluminum oxide (Al2O3) may be 26 wt% to 29 wt%, and the content of iron oxide (Fe2O3) may be 5 wt% or less (0 wt% or more).

[0061] The flux (f) according to an embodiment of the present invention can lower the melting point of the slag (S) contained in the holding furnace (100). In addition, the flux (f) can reduce or suppress the reaction of the slag (S) with the refractory material. That is, the flux (f) can change the composition of the slag (S) contained in the holding furnace (100), and the flux (f) can change the composition of the slag (S) so as to reduce or suppress the reaction with the refractory material while lowering the melting point. More specifically, the flux (f) can change the composition of the slag (S) so as to reduce or suppress the reaction with the refractory material including magnesium aluminate spinel (MgAl2O4). Furthermore, the flux can make the basicity of the slag (S) 1.0 or higher.

[0062]

[0063] Table 1 is a table showing the component composition of flux according to Comparative Examples 1 to 12 and Example 1.

[0064] Content of each component included in the flux (weight%) Calcium Oxide (CaO) Silicon Oxide (SiO2) Magnesium Oxide (MgO) Aluminum Oxide (Al2O3) Iron Oxide (Fe2O3) Comparative Example 1: 62.93.80.632.70.0 Comparative Example 2: 56.613.40.529.40.0 Comparative Example 3: 50.323.00.526.20.0 Comparative Example 4: 44.032.70.422.90.0 Comparative Example 5: 37.742.30.419.60.0 Comparative Example 6: 14.342.222.49.811.3 720.337.419.712.79.9 Comparative Example 826.432.617.015.58.5 Comparative Example 932.527.814.318.47.1 Comparative Example 1038.623.011.521.35.6 Comparative Example 1144.718.28.824.14.2 Example 150.713.46.127.02.8 Comparative Example 1256.88.63.329.81.4

[0065] Referring to Table 1, the flux according to Comparative Examples 1 to 12 may not satisfy a calcium oxide (CaO) content of 46 wt% to 56 wt%, a silicon oxide (SiO2) content of 9 wt% to 14 wt%, a magnesium oxide (MgO) content of 4 wt% to 8 wt%, an aluminum oxide (Al2O3) content of 23 wt% to 31 wt%, or an iron oxide (Fe2O3) content of 5 wt% or less (0 wt% or more).

[0066] More specifically, the flux according to Comparative Example 1 has a calcium oxide (CaO) content exceeding 56 wt%, a silicon oxide (SiO2) content less than 9 wt%, a magnesium oxide (MgO) content less than 4 wt%, and an aluminum oxide (Al2O3) content exceeding 31 wt%. The flux according to Comparative Example 2 has a calcium oxide (CaO) content exceeding 56 wt% and a magnesium oxide (MgO) content less than 4 wt%. The flux according to Comparative Example 3 has a silicon oxide (SiO2) content exceeding 14 wt% and a magnesium oxide (MgO) content less than 4 wt%. The flux according to Comparative Example 4 has a calcium oxide (CaO) content of less than 46 wt%, a silicon oxide (SiO2) content exceeding 14 wt%, a magnesium oxide (MgO) content of less than 4 wt%, and an aluminum oxide (Al2O3) content of less than 23 wt%. The flux according to Comparative Example 5 has a calcium oxide (CaO) content of less than 46 wt%, a silicon oxide (SiO2) content exceeding 14 wt%, a magnesium oxide (MgO) content of less than 4 wt%, and an aluminum oxide (Al2O3) content of less than 23 wt%. The flux according to Comparative Example 6 has a calcium oxide (CaO) content of less than 46 wt%, a silicon oxide (SiO2) content of more than 14 wt%, a magnesium oxide (MgO) content of more than 8 wt%, an aluminum oxide (Al2O3) content of less than 23 wt%, and an iron oxide (Fe2O3) content of more than 5 wt%. The fluxes according to Comparative Examples 7 to 10 have a calcium oxide (CaO) content of less than 46 wt%, a silicon oxide (SiO2) content of more than 14 wt%, a magnesium oxide (MgO) content of more than 8 wt%, an aluminum oxide (Al2O3) content of less than 23 wt%, and an iron oxide (Fe2O3) content of more than 5 wt%.The flux according to Comparative Example 11 has a calcium oxide (CaO) content of less than 46 wt%, a silicon oxide (SiO2) content of more than 14 wt%, and a magnesium oxide (MgO) content of more than 8 wt%. The flux according to Comparative Example 12 has a calcium oxide (CaO) content of more than 56 wt%, a silicon oxide (SiO2) content of less than 9 wt%, and a magnesium oxide (MgO) content of less than 4 wt%.

[0067] The flux according to Example 1 has a calcium oxide (CaO) content of 46 wt% to 56 wt%, a silicon oxide (SiO2) content of 9 wt% to 14 wt%, a magnesium oxide (MgO) content of 4 wt% to 8 wt%, an aluminum oxide (Al2O3) content of 23 wt% to 31 wt%, and an iron oxide (Fe2O3) content of 5 wt% or less (0 wt% or more).

[0068]

[0069] Table 2 is a table showing the composition of the slag (hereinafter referred to as the first slag) produced when manufacturing a high-manganese molten metal and the slag (hereinafter referred to as the second slag) produced by mixing the fluxes according to Comparative Examples 1 to 12 and Example 1, respectively. FIG. 3 is a ternary phase diagram of calcium oxide (CaO), aluminum oxide (Al2O3), and manganese oxide (MnO) of the second slag according to Comparative Examples 13 to 15.

[0070] The second slag according to Comparative Example 13 is prepared by mixing the flux according to Comparative Example 1 with the first slag, the second slag according to Comparative Example 14 is prepared by mixing the flux according to Comparative Example 2 with the first slag, the second slag according to Comparative Example 15 is prepared by mixing the flux according to Comparative Example 3 with the first slag, the second slag according to Comparative Example 16 is prepared by mixing the flux according to Comparative Example 4 with the first slag, the second slag according to Comparative Example 17 is prepared by mixing the flux according to Comparative Example 5 with the first slag, the second slag according to Comparative Example 18 is prepared by mixing the flux according to Comparative Example 6 with the first slag, the second slag according to Comparative Example 19 is prepared by mixing the flux according to Comparative Example 7 with the first slag, and the second slag according to Comparative Example 20 is prepared by mixing the flux according to Comparative Example 8 with the first slag. The second slag according to Comparative Example 21 is manufactured by mixing the flux according to Comparative Example 9 with the first slag, the second slag according to Comparative Example 22 is manufactured by mixing the flux according to Comparative Example 10 with the first slag, the second slag according to Comparative Example 23 is manufactured by mixing the flux according to Comparative Example 11 with the first slag, and the second slag according to Comparative Example 24 is manufactured by mixing the flux according to Comparative Example 12 with the first slag.

[0071] The second slag according to Example 2 is prepared by mixing the flux according to Example 1 with the first slag.

[0072] The first slag mixed with the flux according to Comparative Examples 1 to 11 and Example 1 is a slag produced when manufacturing a high-manganese molten metal. In addition, the first slag mixed with the flux according to Comparative Examples 1 to 11 and Example 1 has the same component composition. More specifically, the first slag has a calcium oxide (CaO) content of 16.5 wt%, a silicon oxide (SiO2) content of 16.5 wt%, a magnesium oxide (MgO) content of 2.0 wt%, an aluminum oxide (Al2O3) content of 15.0 wt%, a manganese oxide (MnO) content of 50.0 wt%, and an iron oxide (Fe2O3) content of 0 wt%, based on 100 wt% of the first slag. Then, a first slag having the component composition described above was mixed with the flux according to Comparative Examples 1 to 12 and Example 1 to produce a second slag according to Comparative Examples 13 to 24 and Example 2. At this time, the first slag mixed with the flux according to Comparative Examples 1 to 12 and Example 1 was mixed at the same mixing ratio.

[0073] Content of each component in the second slag (weight%) Basicity (CaO / SiO2) Calcium Oxide (CaO) Silicon Oxide (SiO2) Magnesium Oxide (MgO) Aluminum Oxide (Al2O3) Manganese Oxide (MnO) Iron Oxide (Fe2O3) Comparative Example 13 57.35.30.73 0.66 01.6 Comparative Example 14 51.813.80.72 7.76 01.3 Comparative Example 15 46.22 2.20.62 4.96 01 Comparative Example 16 40.73 0.70.62 26 00.8 Comparative Example 17 35.23 9.20.519.16 00.6 Comparative Example 18 14.53 9.11 9.91 0.56 100.7 Comparative Example 19 19 .934.917.51368.70.8 Comparative Example 2025.230.715.115.567.50.9 Comparative Example 2130.626.412.71866.21 Comparative Example 2235.922.210.320.5651.1 Comparative Example 2341.3187.923.163.71.2 Example 246.613.85.525.662.51.3 Comparative Example 24529.53.128.161.21.5

[0074] In order to minimize the reactivity between the inner member (110b) of the heat retention furnace (100) formed of basic refractory material and the slag, the basicity of the slag must be 1.0 or higher. Referring to Table 2, the second slag according to Comparative Examples 16 to 20 has a basicity of less than 1.0, while the second slag according to Comparative Examples 13 to 15, Comparative Examples 21 to 24, and Example 2 has a basicity of 1.0 or higher. Accordingly, an evaluation of the reactivity with the liquidus line and refractory specimens was performed according to the change in the component composition of the second slag according to Comparative Examples 13 to 15, Comparative Examples 21 to 24, and Example 2.

[0075] First, the liquidus line according to the change in component composition was examined for the second slag according to Comparative Examples 13 to 15 using thermodynamic software. Specifically, the component composition of the second slag according to Comparative Examples 13 to 15 and a temperature value of 1450℃ were input into the thermodynamic software to derive a ternary phase diagram of calcium oxide (CaO), aluminum oxide (Al2O3), and manganese oxide (MnO), and the result may be as shown in Fig. 3.

[0076] In FIG. 3, S13 is the second slag according to Comparative Example 13 on the ternary phase diagram, S14 is the second slag according to Comparative Example 14 on the ternary phase diagram, and S15 is the second slag according to Comparative Example 15 on the ternary phase diagram.

[0077] Referring to FIG. 3, when examining the liquidus lines of the second slags (S13, S14, S15) according to Comparative Examples 13 to 15, it can be seen that each of the second slags (S13, S14, S15) according to Comparative Examples 13 to 15 enters the liquid phase region as the content of manganese oxide (MnO) increases. In addition, when comparing the liquid phase regions inside the liquidus lines of the second slags (S13, S14, S15) according to Comparative Examples 13 to 15, the liquid phase region of the second slag according to Comparative Example 15 is the widest.

[0078]

[0079] In order to suppress or prevent the tapping port from being blocked by slag inside the holding furnace (100), the slag must remain in a liquid state even if the content of manganese oxide (MnO) increases. That is, as air is introduced into the holding furnace (100), the content of manganese oxide (MnO) increases, and even if the composition of the slag changes, the slag must remain in a liquid state. To this end, the melting point of the slag must be low even if the composition of the slag changes due to an increase in the content of manganese oxide (MnO). Accordingly, among the second slags according to Comparative Examples 13 to 15, Comparative Example 15, which has the widest liquid region, was selected. Then, a reactivity evaluation with a refractory specimen was performed using the selected Comparative Example 15.

[0080]

[0081] Figure 4 is an experimental apparatus for testing the reactivity of slag and refractory material.

[0082] The experimental apparatus (10) may be a Finger Rotating Test (FTR). Referring to FIG. 4, the experimental apparatus (10) may include a chamber (11) having an internal space, a crucible (12) having an internal space that can be placed in the internal space of the chamber (11), a crucible support (13) that can be placed in the internal space of the chamber (11) to support the crucible (12), a specimen support (14) connected to the chamber (11) to support and rotate a specimen (R) formed of refractory material, a driving unit (15) connected to the specimen support (14) to supply rotational power, and a heater (17) that can be installed in the chamber (11) to heat the crucible (12).

[0083] The following describes an experimental method for the reactivity between the second slag and the refractory specimen according to Comparative Example 15. First, a specimen (R) is prepared using refractory material. At this time, the specimen (R) is prepared using refractory material containing magnesium aluminate spinel (MgAl2O4). Next, the second slag (S) according to Comparative Example 15 is loaded into the interior of the crucible (12). The second slag (S) loaded into the interior of the crucible (12) may be in a liquid state. Then, after supporting the specimen (R) on the specimen support (14), the specimen (R) is immersed in the second slag (S) according to Comparative Example 15. Then, the heater (17) is operated to maintain the internal temperature of the crucible (12) at 1450°C, and the specimen support (14) is rotated at 200 rpm using the drive unit (15). These conditions were maintained for 2 hours. That is, the experiment was conducted for 2 hours.

[0084] In addition, manganese oxide (MnO) was added to the second slag according to Comparative Example 15 to produce a slag with a manganese oxide (MnO) content of 50 wt%. For convenience of explanation, the slag produced by adding manganese oxide (MnO) to the second slag according to Comparative Example 15 and having a manganese oxide (MnO) content of 50 wt% will be referred to as the "second slag according to Comparative Example 25." That is, the second slag according to Comparative Example 25 may refer to a slag in which the content of manganese oxide (MnO) contained in the second slag according to Comparative Example 15 has been varied (increased).

[0085] In addition, an experiment was conducted on the reactivity with a refractory specimen (R) using the second slag according to Comparative Example 25. At this time, since the method of the reactivity experiment between the second slag according to Comparative Example 25 and the refractory specimen (R) was performed in the same way as the reactivity experiment between the second slag according to Comparative Example 15 and the refractory specimen (R), a description thereof is omitted.

[0086] Figure 5 is a photograph of a specimen before the experiment, a specimen (R) after the experiment using the second slag according to Comparative Example 15, and a specimen (R) after the experiment using the second slag according to Comparative Example 25.

[0087] Whether the specimen (R) is eroded and the amount of erosion can be determined by comparing at least one of the size and shape of the specimen (R) before the experiment with at least one of the size and shape of the specimen (R) after the experiment.

[0088] Referring to Fig. 5, if photographs of the specimen before the experiment, the specimen after the experiment using the second slag according to Comparative Example 15, and the specimen after the experiment using the second slag according to Comparative Example 25 are compared, it can be confirmed that the specimens have been eroded. That is, it can be confirmed that the specimen after the experiment using the second slag according to Comparative Example 15 and the specimen after the experiment using the second slag according to Comparative Example 25 were each significantly eroded by the second slag. At this time, it can be confirmed that the amount of erosion in the specimen after the experiment using the second slag according to Comparative Example 25 is greater than that of Comparative Example 15.

[0089] From this, it can be seen that the second slag according to Comparative Example 15 has increased reactivity with refractory material containing magnesium aluminate spinel (MgAl2O4) when the content of manganese oxide (MnO) increases. This implies that when the second slag according to Comparative Example 15 is contained in the internal space of the holding furnace (100), the inner member (110b) formed of refractory material containing magnesium aluminate spinel (MgAl2O4) may be eroded when the content of manganese oxide (MnO) of the slag increases due to the atmosphere introduced into the holding furnace (100). Furthermore, the second slag according to Comparative Example 15 is manufactured using the flux according to Comparative Example 3. Therefore, it can be seen that the flux according to Comparative Example 3 cannot alter the composition of the slag to reduce or suppress the reaction with the refractory material.

[0090]

[0091] FIG. 6 is a ternary phase diagram of calcium oxide (CaO), aluminum oxide (Al2O3), and manganese oxide (MnO) of the second slag according to Comparative Examples 21 to 24 and Example 2.

[0092] Next, the liquidus line according to the change in the component composition of the second slag according to Comparative Examples 21 to 24 and Example 2, which have a basicity of 1.0 or higher, was examined. In order to examine the liquidus line according to the change in the component composition of the second slag according to Comparative Examples 21 to 24 and Example 2, the component composition of the second slag according to Comparative Examples 21 to 24 and Example 2 and a temperature value of 1450℃ were input into thermodynamic software to derive a ternary phase diagram of calcium oxide (CaO), aluminum oxide (Al2O3), and manganese oxide (MnO), and the result may be as shown in Fig. 6.

[0093] In FIG. 6, S21 to S24 are second slags according to Comparative Examples 21 to 24 on the ternary phase diagram, and S2 is a second slag according to Example 2 on the ternary phase diagram.

[0094] Comparing FIG. 3 and FIG. 6, it can be seen that the liquid phase region of the second slag (S13, S14, S15) according to Comparative Examples 13 to 15 is relatively narrower than the liquid phase region of the second slag according to Comparative Examples 21 to 24 and Example 2.

[0095] Referring to FIG. 6, the second slag (S21, S22) according to Comparative Example 21 and Comparative Example 22 exists as a solid at 1450°C regardless of fluctuations in the content of manganese oxide (MnO). It can be confirmed that the second slag according to Comparative Example 23 exists as a liquid only when the content of manganese oxide (MnO) is significantly high. Conversely, in Comparative Example 24, it is determined that the fraction of the solid phase increases when the content of manganese oxide (MnO) increases.

[0096] On the other hand, it can be seen that the second slag according to Example 2 can exist in a liquid state even if the content of manganese oxide (MnO) increases to a predetermined range. That is, compared to Comparative Examples 21 to 24, the second slag according to Example 2 has a wider liquid phase region. Therefore, a reactivity evaluation with a refractory specimen was performed using the second slag according to Example 2.

[0097] The method for testing the reactivity between the second slag and the refractory specimen (R) according to Example 2 was performed in the same manner as the method for testing the reactivity between the second slag and the refractory specimen (R) according to Comparative Example 15, so a description thereof is omitted.

[0098] Figure 7 is a photograph of a specimen before the experiment, a specimen after the experiment using the second slag according to Example 2, a specimen after the experiment using the second slag according to Example 3, and a specimen after the experiment using the second slag according to Example 4.

[0099] The second slag according to Examples 3 and 4 is prepared by adding manganese oxide (MnO) to the second slag according to Example 2, wherein the second slag according to Example 3 has a manganese oxide (MnO) content of 30 wt%, and the second slag according to Example 4 has a manganese oxide (MnO) content of 50 wt%. Accordingly, the second slag according to Examples 3 and 4 may refer to a slag in which the content of manganese oxide (MnO) contained in the second slag according to Example 2 has been varied (increased).

[0100] Referring to FIG. 7, when comparing the specimen before the experiment with the specimen after the experiment using the second slag according to Examples 2 to 4, it can be confirmed that the specimen was hardly eroded or was not eroded at all after the experiment. From this, it can be seen that even if the second slag according to Example 2 undergoes a change in composition in which the content of manganese oxide (MnO) increases due to the influx of air, the reactivity with the refractory material containing magnesium aluminate spinel (MgAl2O4) does not increase or is minimized.

[0101] Therefore, when the second slag according to Example 2 is contained in the internal space of the holding furnace (100), even if the content of manganese oxide (MnO) of the second slag increases due to the atmosphere introduced into the holding furnace (100) (change in the composition of the slag components), it can be seen that the inner member (110b) of the holding furnace (100), formed of a refractory material including magnesium aluminate spinel (MgAl2O4), is not eroded by the second slag or erosion is minimized.

[0102] In addition, the second slag according to Example 2 is manufactured using the flux according to Example 1. Therefore, it can be seen that the flux according to Example 1 can change the composition of the slag to reduce or suppress the reaction with the refractory material. More specifically, the flux can change the composition of the first slag to form a second slag that can reduce or suppress the reaction with the refractory material containing magnesium aluminate spinel (MgAl2O4).

[0103] Referring to Table 1, the flux according to Example 1 satisfies the component composition according to the embodiment of the present invention. That is, the flux according to Example 1 has a calcium oxide (CaO) content of 46 wt% to 56 wt%, a silicon oxide (SiO2) content of 9 wt% to 14 wt%, a magnesium oxide (MgO) content of 4 wt% to 8 wt%, an aluminum oxide (Al2O3) content of 23 wt% to 31 wt%, and an iron oxide (Fe2O3) content of 5 wt% or less (0 wt% or more).

[0104] Therefore, it can be seen that when the flux according to the embodiments of the present invention is introduced into a holding furnace, a slag (second slag) that can exist in a liquid state can be formed even if the content of manganese oxide (MnO) increases due to the influx of atmosphere. That is, the flux according to the embodiments of the present invention can lower the melting point of the slag.

[0105] In addition, when the flux according to the embodiment of the present invention is introduced into the holding furnace (100), the basicity of the slag contained in the holding furnace (100) can be made to be 1.0 or higher. Furthermore, when the flux according to the embodiment of the present invention is introduced into the holding furnace (100), it can be seen that a slag (second slag) with low or no reactivity with the inner member (110b) of the holding furnace (100) made of refractory material can be formed. That is, the flux according to the embodiment of the present invention can form a slag with low or no reactivity with the refractory material including magnesium aluminate spinel (MgAl2O4).

[0106]

[0107] FIG. 8 is a graph showing the melting point of the second slag according to the content of the flux according to Example 1 for 100 weight% of the second slag.

[0108] Here, the second slag is a slag produced by adding the flux according to Example 1 to the first slag produced when manufacturing the high-manganese molten metal.

[0109] For the experiment, a first slag generated when producing a high-manganese molten metal was prepared, and a flux according to Example 1 was prepared. Then, a second slag was prepared by mixing the first slag and the flux according to Example 1. At this time, the content ratio of the flux according to Example 1 included in the second slag was varied. That is, the content ratio of the flux according to Example 1 to 100 wt% of the second slag was adjusted to 0 wt% to 100 wt%. At this time, a content ratio of the flux according to Example 1 to 100 wt% of the second slag being 0 wt% or 100 wt% may mean that the first slag and the flux according to Example 1 were not mixed.

[0110] Referring to FIG. 8, it can be seen that the melting point of the second slag changes as the content ratio of the flux according to Example 1 contained in the second slag increases. The holding furnace (100) maintains the temperature of the high-manganese molten metal (M) at a temperature of 1400°C to 1500°C, and referring to FIG. 8, the melting point of the second slag is 1500°C or lower regardless of the content ratio of the flux. From this, it can be seen that when the flux according to the embodiment of the present invention is introduced into the holding furnace (100), the melting point of the second slag can be maintained at the temperature maintained by the holding furnace (100) or lower, without being significantly affected by the content ratio of the first slag and the flux. That is, the melting point of the slag contained in the holding furnace can be lowered to 1500°C or lower simply by introducing the flux according to the embodiment of the present invention.

[0111]

[0112] The flux according to the embodiments of the present invention can lower the melting point of slag contained in a holding furnace and can make the basicity 1.0 or higher. In addition, the flux can form slag that has low reactivity or does not react with the refractory material forming the holding furnace.

[0113] Therefore, it is possible to suppress or prevent the tapping port of the holding furnace from being blocked by high-melting-point slag, or the inner wall of the holding furnace formed of refractory material from being eroded by slag. Consequently, the lifespan of the holding furnace can be extended, and the operability of the holding furnace can be improved.

[0114] The flux according to the embodiments of the present invention can lower the melting point of slag contained in a holding furnace and control the basicity. In addition, the flux can change the composition of the slag so that it has low reactivity with or does not react with the refractory material constituting the holding furnace.

Claims

1. A flux that can be introduced into the internal space of a holding furnace capable of accommodating high-manganese molten metal, A flux comprising, based on 100 weight% of the flux, 46 weight% to 56 weight% of calcium oxide, 9 weight% to 14 weight% of silicon oxide, 4 weight% to 8 weight% of magnesium oxide, and 23 weight% to 31 weight% of aluminum oxide.

2. In Claim 1, A flux containing 0% or more and 5% or less of iron oxide with respect to 100% by weight of the above flux.

3. A method of operating a holding furnace capable of maintaining high-manganese molten metal, A process of opening the opening of the holding furnace to charge high-manganese molten metal into the internal space of the holding furnace; and A method of operating a holding furnace comprising the process of introducing a flux into the internal space of the holding furnace, wherein, with respect to 100 weight% of the flux, calcium oxide comprises 46 weight% to 56 weight%, silicon oxide comprises 9 weight% to 14 weight%, magnesium oxide comprises 4 weight% to 8 weight%, and aluminum oxide comprises 23 weight% to 31 weight%.

4. In Claim 3, A method of operating a heat retention furnace in which the above flux contains 0% or more and 5% or less of iron oxide with respect to 100% by weight of the above flux.

5. In Claim 3, A method of operating a holding furnace comprising: a process of producing a second slag by reacting a first slag floating on the surface of a high-manganese molten metal contained in the internal space of the holding furnace with a flux introduced into the interior of the holding furnace.

6. In Claim 3, A method of operating a holding furnace, comprising the process of controlling the temperature of the internal space of the holding furnace while the molten high-manganese metal is contained in the internal space of the holding furnace, thereby maintaining the temperature of the molten high-manganese metal contained in the internal space of the holding furnace at 1400℃ to 1500℃.

7. In Claim 5, After the process of introducing the flux is completed, the process of closing the opening of the holding furnace; A process of opening the tapping port of the above-mentioned holding furnace to discharge the high-manganese molten metal contained in the internal space of the above-mentioned holding furnace through the tapping port; and The process of closing the above-mentioned discharge port after the above-mentioned discharge is completed; and A method of operating a holding furnace in which, in at least one of the processes of charging high-manganese molten metal into the internal space of the holding furnace and tapping it out, air is introduced into the internal space of the holding furnace, thereby increasing the content of manganese oxide contained in the second slag.

8. In Claim 7, A method of operating a holding furnace in which the basicity of the second slag, with an increased manganese oxide content, is 1.0 or higher.

9. In Claim 7, A method of operating a holding furnace in which the melting point of the second slag, having an increased manganese oxide content, is 1350°C to 1500°C.

Images