Patent Grant
10077482
The present invention relates to a molten metal refining method and device, and more particularly, to a molten metal refining method and device which is capable of efficiently controlling the phosphorus concentration in ferromanganese molten metal.
In general, since phosphorus (P) is present as an impurity in steel and degrades the quality of a steel product, for example, causes high temperature brittleness, the phosphorus (P) concentration in steel is preferably reduced except for a special case. Accordingly, a dephosphorization operation for removing phosphorus (P) in ferromanganese molten metal is performed.
In a typical dephosphorization operation for manufacturing ferromanganese, molten metal is charged into a ladle, an impeller is then dipped into the molten metal, and then the molten metal is stirred. Here, as illustrated in
A stirring flow according to the operation of this impeller 20 will be simply described as follows. As illustrated in
Thus, there are limitations in that it is not easy for an operator to remove phosphorus (P) up to a desired phosphorus concentration, and it takes a long time to remove phosphorus (P) up to a target value.
Also, there are limitations in that since a solid phase dephosphorization agent at room temperature is inputted into the molten metal, the temperature of the molten metal is decreased to thereby decrease a dephosphorization effect and a temperature-raising process to increase the temperature of the molten metal is required in a subsequent process.
In order to address the foregoing problems, the present invention provides a molten metal refining method and device which is capable of improving dispersion performance of dephosphorization agents introduced into the molten metal by improving the stirring efficiency of the molten metal.
The present invention also provides a molten metal refining method and device which is capable of efficiently controlling the phosphorus (P) concentration in the molten metal.
The present invention also provides a molten metal refining method and device which is capable of increasing the dephosphorization efficiency by suppressing the decrease in the temperature of the molten metal.
In accordance with an exemplary embodiment, a molten metal refining device for refining molten metal, includes: an impeller extending in a vertical direction over a ladle in which the molten metal is charged; and a liquid dephosphorization agent supply part disposed over the ladle to supply a molten state liquid dephosphorization agent to a top portion of the molten metal, wherein the impeller comprises: an impeller body; blades provided on an upper outer circumferential surface of the impeller body; a supply pipe which is disposed inside the impeller body along a lengthwise direction of the impeller body and through which a solid dephosphorization agent in a powder state and a transfer gas are supplied; and blowing nozzles partially passing through a lower portion of the impeller body and communicating with the supply pipe.
The blades may be positioned above approximately the midpoint of a total depth of the molten metal, and the blowing nozzles may be positioned under approximately the midpoint of the total depth of the molten metal.
The blades may be disposed in a region of approximately 10% to approximately 30% with respect to a total depth of the molten metal from a molten metal surface of the molten metal.
The liquid dephosphorization agent supply part may be connected to a discharge pipe provided with a heater to heat the liquid dephosphorization agent.
The blades may have upper widths formed greater than lower widths.
The upper widths of the blades may be formed greater than the lower widths of the blades by approximately 5% to approximately 20% of total lengths of the upper widths.
The blades may be formed to have widths of approximately 35% to approximately 45% to an inner diameter of the ladle.
The blades may be provided in plurality and spaced apart from each other about the impeller main body, and inclined surfaces may be formed on at least one side surface facing an adjacent blade.
The one side surface of the blade may be formed to have an angle of approximately 10° to approximately 30° with respect to an upper surface of the blade.
In accordance with an exemplary embodiment, a method of refining molten metal includes: preparing molten metal; dipping an impeller into the molten metal; supplying a liquid dephosphorization agent to an upper portion of the molten metal; and stirring the molten metal by rotating the impeller, wherein a solid dephosphorization agent in a powder state is supplied through a lower portion of the impeller during the stirring of the molten metal.
Slag generated from a previous process may be removed before the dipping of the impeller.
In the dipping of the impeller, blades of the impeller may be disposed above approximately the midpoint of a total depth of the molten metal, and blowing nozzles of the impeller may be disposed under approximately the midpoint of the total depth of the molten metal.
The blades of the impeller may be disposed in a region of approximately 10% to approximately 30% from a molten metal surface of the molten metal.
The stirring may include stirring the molten metal such that a direction of a stirring flow of the molten metal generated from blades of the impeller coincides with a direction of a stirring flow of the molten metal generated by the solid dephosphorization agent blown into the molten metal.
The stirring flow generated from the blades may flow to be separated into upward and downward directions, and an area of the stirring flow of the molten metal in the downward direction from the blades may be greater than an area of the stirring flow of the molten metal in the upward direction from the blades.
The liquid dephosphorization agent supplied to the molten metal may be approximately 50 wt % to approximately 70 wt % with respect to a total weight of the liquid and solid dephosphorization agents.
In the supplying of the solid dephosphorization agent, an inert gas may be supplied together with the solid dephosphorization agent.
The slag may be removed after the stirring of the molten metal.
A molten metal refining method and device according to an embodiment of the present invention may improve the dephosphorization efficiency by improving the dispersion performance of dephosphorization agents which are introduced into the molten metal by providing blades and blowing nozzles to be separated from each other, respectively to upper and lower portions of molten metal. That is, a liquid dephosphorization agent is introduced to an upper portion of the molten metal received in a ladle, the molten metal is stirred by using an impeller including the blades disposed in the upper portion of the molten metal, and a solid dephosphorization agent and a transfer gas are injected through blowing nozzles in a lower portion of the impeller, so that a stirring flow generated by the blades and a stirring flow by substances blown into molten metal through the blowing nozzles coincide with each other and the two flows are integrated with each other to thereby improve the overall stirring power. Thus, the efficiency of stirring by using the impeller is improved in comparison with related arts, the reaction rate between the molten metal and the dephosphorization agents is thereby increased, and thus the refining efficiency is improved.
Also, the decrease in the temperature of the molten metal is suppressed by the introduction of the liquid dephosphorization agent, and thus the dephosphorization efficiency may be further improved.
Hereinafter, embodiments will be described in more detail with reference to the accompanying drawings. The present disclosure may, however, be in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the present disclosure to those skilled in the art. In the drawings, like reference numerals refer to like elements throughout.
First, the present invention relates to a molten metal refining device and a method thereof which are capable of controlling the concentrations of elements such as sulfur (S) and phosphorus (P) contained in the molten metal by mixing an additive in the molten metal. Hereinafter, a device and a method for controlling the phosphorus (P) concentration contained in molten metal by mixing a dephosphorization agent into the molten metal produced from a electric furnace will be described, but the present invention is not limited thereto, and the concentrations of various elements contained in the molten metal may be controlled by mixing various substances into the molten metal according to operation conditions. That is, in an embodiment of the present invention, in order to control the phosphorus concentration in the molten metal, a liquid dephosphorization agent is introduced from the top portion of the molten metal, a solid dephosphorization agent is inputted into the molten metal, and the molten metal is stirred, so that the dispersion efficiencies of the liquid and solid dephosphorization agents in the molten metal may be improved. Thus, the decrease in the temperature of the molten metal is suppressed to improve the reaction efficiency between the phosphorus component and the dephosphorization agent, so that high-quality molten metal may be obtained.
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
Referring to
Referring to
The impeller body 210 is a rotational axis or a major axis of the impeller 200, extends in the lengthwise direction or vertical direction, and may extend to be dipped from the surface of the molten metal to at least a lower region of the molten metal. More specifically, the upper end of the impeller body 210 protrudes over slag, and the lower end of the impeller body 210 extends to the lower region of the molten metal, and thus the lower end of the impeller body 210 may be disposed adjacent to the inner bottom surface of the ladle 100. The impeller body 210 according to an embodiment has a rod shape with the lateral cross-section of a circular shape, but the present invention is not limited thereto, and may have any rod shape which has the lateral cross-section with various shapes which are easily rotatable. The flange 250 may be connected to the upper portion of the impeller body 210, and the flange 250 may be connected to the drive part (not shown) providing torque. Accordingly, the impeller body 210 is rotated by the operation of the drive part, and the blades 220 are rotated together by the rotation of the impeller body 210.
The supply pipe 240 communicates with the blowing nozzle 230 disposed in the lower portion of the impeller body 210, and is used as a moving path of the solid dephosphorization agent injected through the blowing nozzle 230. The supply pipe 240 may also be used as a moving path of the transfer gas for moving and injecting the solid dephosphorization agent to the blowing nozzle 230. Also, only the transfer gas is transferred through the supply pipe 240 so as to be injected from the blowing nozzle 230.
The supply pipe 240 is formed to pass through the inside of the flange 250 and impeller body 210 in the vertical direction. The supply pipe 240 according to an embodiment has a hole shape which is formed by machining the inside of the flange 250 and the impeller body 210, but the present invention is not limited thereto, and the supply pipe 240 may have a structure in which a hollow pipe is inserted into the flange 250 and the impeller body 210. The upper end of this supply pipe 240 may be connected to tanks respectively storing the solid dephosphorization agent with a powder state and the transfer gas, and the lower end thereof communicates with the blowing nozzle 230 disposed in the lower portion of the impeller body 210. Here, the internal cross-sectional area of the supply pipe 240 may be formed equal to or nearly similar to that of the blowing nozzle 230 connected to the supply pipe 240. That is, although a plurality of blowing nozzles 230 may communicate with the supply pipe 240, when the cross-sectional area of the supply pipe 240 is too smaller than that of the blowing nozzles 230, the solid dephosphorization agent may not be easily transferred, or the amount of the solid dephosphorization agent discharged through the plurality of blowing nozzle 230 is not enough due to the small transferred amount, and when the cross-sectional area of the supply pipe 240 is too larger than that of the blowing nozzles 230, the solid dephosphorization agent is transferred too much, and thus the solid dephosphorization agent may not be easily discharged through the blowing nozzles 230.
The blowing nozzles 230 blow the solid dephosphorization agent and the transfer gas into the molten metal. The blowing nozzles 230 are disposed in the lower portion of the impeller body 210, and it is effective that the blowing nozzle 230 be spaced maximally apart from the blades 220 disposed in the upper portion of the impeller body 210. Accordingly, in this embodiment, the blowing nozzles 230 are installed adjacent to the inner bottom surface of the ladle 100, and the blades 220 are installed adjacent to the surface of the molten metal. In other words, the blowing nozzles 230 are individually configured separate from the blades 220, and positioned in a lower region of the molten metal received in the ladle 100.
Also, the blowing nozzles 230 are favorably formed in a direction crossing the extension direction (extending in the vertical direction) of the impeller body 210. The blowing nozzles 230 according to the embodiment are formed to extend in the lateral direction of the impeller body 210, and to be branched in a plurality of directions around the supply pipe 240 which passes through the inner central portion of the impeller body 210. The number of the branched blowing nozzles 230 may be the number corresponding to the number of the plurality of blades 220, or may be less than or more than the number of the blades 220. The blowing nozzles 230 according to the embodiment have shapes which are formed by machining the inside of the impeller body 210 and branched in the lateral direction around the supply pipe 240, but the present invention is not limited thereto, and the blowing nozzles 230 may have structures in which thin hollow pipes are inserted into the lower portion of the impeller body 210.
As illustrated in
Here, the solid dephosphorization agent transferred through the supply pipe 240 and injected through the blowing nozzles 230 is an additive for removing the phosphorus (P) component in the molten metal, and may include at least any one of BaCO3, BaO, BaF2, BaCl2, CaO, CaF2, Na2CO3, Li2CO or NaF which has a powder shape. For example, the solid dephosphorization agent may be BaCO3—NaF based. Also, the transfer gas which is transferred through the supply pipe 240 and injected through the blowing nozzles 230 is provided for suppressing or preventing the clogging of the blowing nozzles 230, and may be an inert gas, such as, argon (Ar) or nitrogen (N2), which does not react with the molten metal or the solid dephosphorization agent.
The blades 220 mechanically stir the molten metal charged in the ladle 100 to disperse or spread the liquid dephosphorization agent and the solid dephosphorization agent introduced into the molten metal. These blades 220 are disposed, in an upper portion of the impeller body 210 to be spaced apart from the blowing nozzles 230. That is, the blades 220 are positioned corresponding to an upper region of the molten metal received in the ladle 100 and individually configured separate from the blowing nozzles 230. For example, the upper surfaces of the blades 220 may be disposed adjacent to the surface of the molten metal. These blades 220 are provided in plurality to be connected to the upper outer circumferential surface of the impeller body 210, and the plurality of blades 220 are disposed at equal intervals to be spaced apart from the outer circumferential surface of the impeller body 210. Also, in order to maximize the stirring efficiency, the plurality of blades 220 may be disposed in a shape, for example, a cross shape, with the impeller body 210 disposed therebetween, and may be disposed such that each pair of the blades 220 may face each other approximately the impeller body 210.
Referring to
Also the heights of the blades 220 may be formed in lengths of approximately 25% to 35% with respect to the upper widths of the blades 220. When the heights of the blades 220 are greater than the suggested range, the contact area between the blades and the molten metal is increased to thereby increase the power consumption for rotating the impeller 200 in comparison with the stirring effect. When the heights of the blades 220 are smaller than the suggested range, there is a limitation in that the stirring efficiency of the molten metal may be decreased.
The blades 220 may be favorably formed to be positioned within 50% from the surface of the molten metal (excluding the liquid dephosphorization agent) when the impeller 200 is dipped into molten metal charged in the ladle 100, and more favorably to be positioned within a range of approximately 10% to approximately 30%. This will be described again in a method for treating the molten metal.
As described above, in the present invention, the blowing nozzles 230 are positioned in the lower region of the molten metal, the blades 220 are separately disposed to be positioned in the upper region of the molten metal, and it is effective that the blades 220 and the blowing nozzles 230 are disposed to be positioned spaced maximally apart from each other. The installation positions of the blowing nozzles 230 and blades 220 according to the embodiment of the present invention will be specifically described as follows. First, for convenience of description, as illustrated in
As such, as the blowing nozzles 230 of the impeller 200 are positioned in the lower region of the molten metal, and the blades 220 are positioned in the upper side of the blowing nozzles 230, the stirring efficiency may be improved in comparison with that in the related art.
The liquid dephosphorization agent supply part 300 is provided over the ladle 100 to supply the high-temperature liquid dephosphorization agent to the top portion of the molten metal in the ladle 100. The liquid dephosphorization agent supply part 300 is provided with a melting furnace to melt the solid dephosphorization agent. The liquid dephosphorization agent supply part 300 may be provided with an opening/closing device for supplying or blocking the molten liquid dephosphorization agent and adjusting the supply amount. The opening/closing device may be implemented as various shapes such as a valve, a stopper, or a sliding gate.
Also, a discharge pipe 400 for supplying the liquid dephosphorization agent, which is discharged from the melting furnace, in a high-temperature state to the molten metal may be connected to the liquid dephosphorization agent supply part 300. The discharge pipe 400 may be provided with a heater (not shown) for heating the liquid dephosphorization agent transferred along the inside of the discharge tube 400, and may also be provided with a heat insulation member (not shown) suppressing the temperature decrease of the liquid dephosphorization agent.
As described above, the molten metal refining device according to the embodiment of the present invention stirs the molten metal while supplying a high-temperature liquid dephosphorization agent to the upper portion of the molten metal and discharging the solid dephosphorization agent into the molten metal, and may thus suppress the temperature decrease of the molten metal and quickly and uniformly disperse the dephosphorization agents in the molten metal. Thus, the phosphorus component contained in the molten metal is easily controlled, so that high-quality molten metal may be produced.
Hereinafter, the molten metal refining method according to an embodiment of the present invention will be described.
First, the ferromanganese molten metal produced from an electrical furnace is tapped to the ladle 100, is then heated by the ladle furnace device, and is then transferred to a workplace for dephosphorization. In the workplace for the dephosphorization, an impeller for stirring the molten metal and a liquid dephosphorization agent supply part 300 for mixing the dephosphorization agent to the molten metal are provided. Here, in the liquid dephosphorization agent supply part 300, the dephosphorization agent which is formed by melting a solid dephosphorization agent may be introduced.
When the molten metal is prepared (S100), slag (LF slag) generated in the process of heating the molten metal is removed (S110).
After removing the slag, the impeller provided over the ladle 100 is lowered to be dipped into the molten metal (S120). Here, to prevent blowing nozzles formed in the lower portion of the impeller from being clogged, a transfer gas is supplied through a supply pipe inside the impeller and is discharged through the blowing nozzles 230.
Next, the liquid dephosphorization agent in the melting furnace is constantly discharged by using an opening/closing device of the liquid dephosphorization supply part 300 and is thereby introduced to the top portion of the molten metal through a discharge pipe 400 (S130). Here, when the liquid dephosphorization agent starts to be introduced to the molten metal, the impeller is rotated to stir the molten metal (S140). Simultaneously, the transfer gas and the solid dephosphorization agent are supplied through a supply pipe 240 of the impeller, and are then discharged into the molten metal through the blowing nozzles (S150).
When introducing the liquid dephosphorization agent, the liquid dephosphorization agent transferred along the discharge pipe 400 is heated so that the temperature decrease of the liquid dephosphorization agent may be suppressed. Thus, the temperature decrease of the molten metal may be suppressed and the dephosphorization efficiency may thereby be improved. Here, the liquid dephosphorization agent may be introduced by an amount of approximately 50% to approximately 70% to the total weight of the dephosphorization agents (solid and liquid dephosphorization agents) which are introduced for the dephosphorization of the molten metal. When the introduced amount of the liquid dephosphorization agent is smaller than the suggested range, a temperature decrease of the molten metal occurs due to the increase in inputted solid dephosphorization agent, and when the introduced amount of the liquid dephosphorization agent is larger than the suggested range, there is a limitation in that although the temperature decrease of the molten metal may be suppressed, the dephosphorization efficiency does not increase any more or minutely increases.
Subsequently, when the stirring of the molten metal by using the rotation of the impeller for a predetermined time is completed, the rotation of the impeller is stopped, the impeller is then raised to be taken out (S160) from the molten metal, and the slag generated in the dephosphorization process is removed (S170). Here, the stirring of the molten metal may be performed for approximately 5 minutes to approximately 20 minutes. When the molten metal is stirred for a time shorter than the suggested time, the dephosphorization effect of the molten metal is decreased, and when the molten metal is stirred for a time longer than the suggested time, the dephosphorization effect of the molten metal is not only decreased, but there is also a limitation in that a separate process for raising the temperature of the dephosphorized molten metal should be performed in a subsequent process.
As such, when the liquid dephosphorization agent is introduced through the upper portion of the molten metal, the solid dephosphorization agent is inputted into the molten metal, and the impeller is simultaneously rotated, the liquid dephosphorization agent is dispersed while being decomposed into minute liquid drops by the rotation of the impeller and being moved from the upper portion to the lower portion of the molten metal, and the solid dephosphorization agent is dispersed while being moved from the lower portion to the upper portion of the molten metal. Also, the blades of the impeller is disposed adjacent to the surface of the molten metal to form the flow of the molten metal in the upper portion of the molten metal, and the blowing nozzles is disposed in the lower portion of the molten metal to form the flow of the molten metal in the lower portion of the molten metal, so that the dispersion efficiency of the liquid and solid dephosphorization agents introduced to the molten metal may be improved.
The flow of the molten metal formed during stirring the molten metal will be described as follows.
When the impeller body 210 is rotated, the blades 220 are rotated together with the impeller body 210. Also, as illustrated in
Meanwhile, as described in the background art section, a related impeller 20 is provided with a blade 22 in a lower portion of an impeller body 21, and the blade 22 is provided with blowing nozzles 23. That is, in the related impeller 20, the blades 22 and the blowing nozzles 23 are not separated from each other. Here, as illustrated in
Hereinafter, an experiment for optimizing the dephosphorization process to apply the molten metal refining device and the method thereof according to an embodiment of the present invention to an actual operation will be described.
To improve the dephosphorization efficiency of molten metal, for example, ferromanganese, a dephosphorization process was performed by using a BaCO3—NaF-based dephosphorization agent. Also, the temperature of the FeMn molten metal, the introduced rate of dephosphorization agents (liquid and solid dephosphorization agents), and the parameters of the introduced ratio of the liquid dephosphorization agent and the dephosphorization efficiency of the ferromanganese molten metal were compared and analyzed after the dephosphorization process.
In the dephosphorization process, the ferromanganese molten metal was prepared by melting approximately 1.7 ton of ferromanganese metal by using a 2.0 ton-class induction furnace. The prepared ferromanganese molten metal was tapped to a preheated ladle 100, the temperature of the molten metal before the dephosphorization treatment was then measured, and then a test specimen (first specimen) was sampled. Here, the temperature of the molten metal before the dephosphorization treatment was measured approximately 1340° C.
Subsequently, while introducing the solid dephosphorization agent having a powder shape and the liquid dephosphorization agent to the molten metal, the molten metal was stirred by using the impeller. The solid dephosphorization agent was inputted into the molten metal through the blowing nozzles of the impeller by using argon gas as transfer gas, and the liquid dephosphorization agent was introduced to the top portion of the molten metal after melting by using an indirect heating-type melting furnace using a carbide (SiC) heat-generating body.
The ladle 100 receiving the dephosphorized molten metal was moved to a sampling place, the temperature of the molten metal after dephosphorization is measured, and a specimen (second specimen) was sampled. Then, the ladle 100 was moved to an iron casting treatment place, and an iron casting treatment was performed by using an iron casting machine, so that the dephosphorization experiment was completed.
Subsequently, components of the sampled specimens were verified through a wet-type analysis by using an inductively coupled plasma spectrometry (ICP) analysis method.
For example, when the temperature of the molten metal after the dephosphorization process is approximately 1280° C., it may be understood that the actual yield (approximately 90%) of the molten metal when only the liquid dephosphorization agent is introduced is shown greater than that the actual yield (approximately 80%) of the molten metal when only the solid dephosphorization agent is inputted.
Also, the behavior of the actual yield is very sensitive to the temperature of the molten metal after the dephosphorization process. When the temperature of the molten metal is approximately the early 1280° C.'s, the actual yield of the molten metal is found to be a level of approximately 80% to approximately 90%. However, although not shown, when the temperature of the molten metal is approximately the early 1270° C.'s, which is lower by approximately 10° C., the yield of the molten metal is a level of approximately 65% to approximately 75%, and it is found that the lower the temperature of the molten metal, the lower the actual yield of the molten metal. Accordingly, to improve the actual yield of the molten, the temperatures of the molten metal before and after the dephosphorization process need to be thoroughly managed.
Hereinafter, when the molten metal is refined by using a related refining device in which blades and blowing nozzles are formed in a lower portion of an impeller body, an experiment was performed by using a water model to verify the stirring effect. The water model experiment simulates a mass transfer phenomenon between the molten metal and the dephosphorization agent in an actual dephosphorization operation.
First, the water model experiment was performed as follows.
For the experiment, the same amount of water was introduced into a first to sixth containers of the same size, and thymol (C10H14O) which had equilibrium distribution ratio to water and oil of approximately 350 or more was introduced into each of the containers and was then dissolved, so that the phosphorus component in the molten metal was simulated. Subsequently, an impeller was dipped in the water, and the water was then rotationally stirred at a constant speed. During stirring, paraffin oil corresponding to the liquid dephosphorization agent was supplied to the top portion of the water. Here, to control the supplying speed of the paraffin oil, a valve for turning on/off the discharge of the paraffin oil and a valve for adjusting the supplying speed were used. The position to which the paraffin oil is supplied was configured as the point of approximately 25% of the radius toward the outer side at the top portion of the container in consideration of the position of the discharge pipe in the actual process.
The blowing nozzles of the impeller did not blow powder but the paraffin oil and nitrogen gas. This experiment is for reviewing the stirring effect of the water and the paraffin oil, and it is sufficient to inject the liquid paraffin oil thorough the blowing nozzles. The paraffin oil was supplied by an amount of 10.8 liters for approximately 10 minutes to simulate the dephosphorization agent rate of approximately 100 kg/ton-FeMn. Also, the rotational speed of the impeller was set approximately 120 rpm, and the flow rate of nitrogen gas which is the transfer gas was applied as approximately 120 liter/min.
To confirm the flow of the water and the paraffin oil, that is, a stirring phenomenon, a video camera was used for imaging, and the water specimen was sampled one time per two minutes at the point approximately 10 mm from the bottoms of first to sixth containers. The stirring continued for approximately 20 minutes, and the experiment was then completed.
The experiment was performed a plurality of times under conditions as described in Table 1 below.
To review the stirring effect according to whether the liquid and solid dephosphorization agents are introduced and the blade position, the experiment was performed while changing the experiment conditions as shown in the above table.
An analysis of thymol in water was performed and interpreted by using mass transfer equations as described below. Here, the total reaction speed becomes the flow speed according to the thymol dispersion speed in the mass transfer resistance layer which exists at the water phase side. This mass transfer equation is given as Equation 1.
where, Cw is the concentration of thymol in a water phase, and C′w is the concentration of thymol in a mass transfer resistance layer in the water phase side. Kw is a mass transfer coefficient in the water phase, Vw is a volume of the water, and A represents an interface area between the water and oil. In Equation 1, it is assumed that there is no change in a volume in each phase, the interface area is constant, and there is no interface resistance.
The equilibrium distribution ratio β is the same as Equation 2.
Here, the reason for C′o=Co is because it is not necessary to consider the mass transfer resistance layer existing at an oil phase due to using the thymol. That is, it is assumed that the concentration of the oil phase is constant.
In consideration of the mass equilibrium of the thymol, Equation 3 may be derived.
CoVo=(Cwo−Cw)·Vw [Equation 3]
where, Cwo is an initial concentration of thymol in the water phase side, and Co and Cw are respectively the thymol concentration of the oil phase side and the thymol concentration of the water phase side at a certain time t.
When the above equations are combined in consideration of the equilibrium at the interface, all concentration terms may be expressed by the Cw term, and may be expressed as the Equation 4 below.
Since the equilibrium distribution ratio β has a constant value within the range of the change of the thymol concentration in this experiment, when Equation 4 is integrated, the following Equation 5 is derived.
The value of a mass transfer variable KwA may be obtained from the Equation 5, and when the mass transfer variable has a high value, it may be understood that the mass transfer speed becomes faster. That is, it means that the greater the variable KwA, the wider the reaction interface between the molten metal and the dephosphorization agent, and the higher the reactivity by stirring.
First, when the immersion depth of the blade is disposed at a position of approximately 70% from the liquid surface (water surface) as in the first, third, and fifth experiment examples, the value (reaction efficiency) of the term KwA/Vw derived by using the analyzed thymol value was shown in a sequence that first experiment example>third experiment example>fifth experiment example as shown in
On the contrary, when the immersion depth of the blade is disposed at a position of approximately 20% from the liquid surface of the water (water surface) as in the fourth experiment example and the sixth experiment example, the value (reaction efficiency) of the term KwA/Vw derived by using the analyzed thymol value was shown in a sequence that second experiment example>sixth experiment example>fourth experiment example as illustrated in
Consequently, it may be said that when the disposition position of the blade is deep, the reaction efficiency of the solid dephosphorization agent supply method is better than that of the liquid dephosphorization agent supply method, and when the disposition position of the blade is shallow, the reaction efficiency of the liquid dephosphorization agent supply method may be better than that of the solid dephosphorization agent supply method. It may be understood that in the method of simultaneously supplying the liquid and solid dephosphorization agents, the reaction efficiency is better than in the case in which only the liquid dephosphorization agent or only the solid dephosphorization agent is used regardless of the disposition position of the blade.
As understood from the result of the water model experiment, in order to easily introduce the liquid dephosphorization agent to be supplied to the top portion of the molten metal, the smaller the immersion depth of the blade, the better. Also, in the method of supplying the solid dephosphorization agent through the blowing nozzle, in order to secure the chance and the time for reaction between the solid dephosphorization agent and the phosphorus component contained in the molten metal, the greater the immersion depth of the blowing nozzle, the better.
Here, the cases in which the molten metal refining devices according to an embodiment of the present invention and according to a related art were compared with each other. The example in which the molten metal refining device according to the related art is the same as the above-described first, third, and fifth experiment examples. Referring to
Also, as shown below in Table 2, when the improved molten metal refining device according to an embodiment of the present invention regardless of the flow rate of the molten metal used for stirring is used, a maximum effective reaction area is reached within a shorter time than in the case in which the molten metal refining device according to a related art. This shows that when the molten metal refining device according to an embodiment of the present invention, the dephosphorization may be performed within a shorter time and the dephosphorization efficiency may be increased through this.
Also, an experiment in which the molten metal was refined under conditions similar to the actual operation on the basis of the water model experiment was performed.
The experiment was performed by using the impeller in which the present invention is applied and the impeller according to a related art. The experiment used the impeller in which the present invention is applied and the impeller according to a related art, and was performed by applying similar dephosphorization agent rates.
Referring to Table 3, it may be understood that when nearly similar amounts of dephosphorization flux are supplied, a dephosphorization finishing temperature, a dephosphorization ratio, and an actual yield of iron casting are improved in the case of the present invention in comparison with the related art.
Also, the dephosphorization reaction efficiencies according to the methods of introducing dephosphorization agents were compared with one another. Table 4 shows the results of the dephosphorization process of the molten metal in the cases in which only the solid dephosphorization agent is inputted, only the liquid dephosphorization agent is introduced, and the solid and liquid dephosphorization agents are introduced together.
As shown in Table 4, it may be shown that in the case in which the molten metal is dephosphorized by using the solid and the liquid dephosphorization agents are used together, the dephosphorization reaction efficiency is shown to be remarkably higher than in the case in which only the liquid or solid dephosphorization agent is used. In addition, although worse than in the case in which only the liquid dephosphorization agent is used in an aspect of an available temperature range, it is possible to obtain the temperature range wider by approximately 50° C. than in the case in which only the solid dephosphorization agent is used, and thus it may be expected to remarkably contribute to the improvement of the actual yield of molten metal.
Although the present invention has been described with reference to the specific embodiments, it is not limited thereto but limited by following claims. Therefore, it will be readily understood by those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the present invention defined by the appended claims.
A molten metal refining method and device according to the present invention may improve a dephosphorization efficiency by improving the dispersion performance of dephosphorization agents which are introduced into the molten metal by providing blades and blowing nozzles to be separate from each other, and thus high-quality molten metal may be produced and the reliability of products using the molten metal may be improved.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2013-0093720 | Aug 2013 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2013/008535 | 9/25/2013 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2015/020262 | 2/12/2015 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4240618 | Ostberg | Dec 1980 | A |
| 4282032 | Nagoya et al. | Aug 1981 | A |
| 4363657 | Boscaro et al. | Dec 1982 | A |
| 4662937 | Katayama et al. | May 1987 | A |
| 4684403 | Lee et al. | Aug 1987 | A |
| 4752327 | Lee et al. | Jun 1988 | A |
| 6299828 | Eckert | Oct 2001 | B1 |
| Number | Date | Country |
|---|---|---|
| 102424879 | Apr 2012 | CN |
| 202380011 | Aug 2012 | CN |
| 102719588 | Oct 2012 | CN |
| 47051681 | Dec 1972 | JP |
| 491967 | Jan 1974 | JP |
| 52077910 | Dec 1975 | JP |
| 57073107 | May 1982 | JP |
| 57098617 | Jun 1982 | JP |
| 57152406 | Sep 1982 | JP |
| 59070706 | Apr 1984 | JP |
| 59093814 | May 1984 | JP |
| 59093814 | May 1984 | JP |
| 60200904 | Oct 1985 | JP |
| 61199011 | Sep 1986 | JP |
| 62067148 | Mar 1987 | JP |
| 04297516 | Oct 1992 | JP |
| 07331313 | Dec 1995 | JP |
| 2001064713 | Mar 2001 | JP |
| 2003119509 | Apr 2003 | JP |
| 2005068506 | Mar 2005 | JP |
| 2006161079 | Jun 2006 | JP |
| 2007092158 | Apr 2007 | JP |
| 2007113042 | May 2007 | JP |
| 2007277669 | Oct 2007 | JP |
| 2009114506 | May 2009 | JP |
| 2010116612 | May 2010 | JP |
| 2010185114 | Aug 2010 | JP |
| 1020040053602 | Jun 2004 | KR |
| 1020100076116 | Jul 2010 | KR |
| 1020120028761 | Mar 2012 | KR |
| 101218923 | Jan 2013 | KR |
| 539947 | Feb 1976 | SU |
| WO-2004013358 | Feb 2004 | WO |
| Entry |
|---|
| JP 59093814-A machine translation (Year: 1984). |
| SU 539947-A machine translation (Year: 1976). |
| WO 2004-013358-A (Year: 2004). |
| JP 2001-064713-A (Year: 2001). |
| JP 60200904-A machine translation (Year: 1985). |
| JP 57098617-A machine translation (Year: 1982). |
| JP 57073107-A machine translation (Year: 1982). |
| JP 2005-068506 machine translation (Year: 2005). |
| International Search Report—PCT/KR2013/008535 dated Apr. 28, 2014. |
| PCT Written Opinion—PCT/KR2013/008535 dated Apr. 28, 2014, citing JP 2005-068506, JP 2007-277669, JP 2003-119509, JP 2010-116612 and KR 10-2004-0053602. |
| Japanese Office Action—Japanese Application No. 2016-532999 dated Nov. 14, 2017, citing JP 2005-068506, JP 61-199011, JP 47-51681, JP 2007-113042, JP 59-93814, JP 2009-114506, JP 04-297516 AND JP 07-331313. |
| European Search Report—European Application No. 13891083.1, dated Mar. 3, 2017, citing JP 2005 068506, CN 202 380 011, JP 2009 114506 and U.S. Pat. No. 6,299,828. |
| Japanese Office Action—Japanese Application No. 2016-532999 dated May 21, 2018, citing JP 2005-068506, JP 61-199011, JP 47-51681, JP 2007-113042, JP 59-93814, JP 04-297516, JP 07-331313, JP 59-70706 and JP 49-1967. |
| Number | Date | Country | |
|---|---|---|---|
| 20160186277 A1 | Jun 2016 | US |
