JP3654248B2 - Method for refining molten metal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for refining molten metal, particularly molten steel, and relates to a method for stirring between molten steel, gas, and slag that strongly affects the refining speed and the content of the refining reaction.
[0002]
[Prior art]
In the refining of oxidation, reduction, degassing, and non-metallic inclusions of molten steel, stirring of molten steel and slag is an important key for promoting the reaction. In order to meet the product specifications and the next casting process, the molten steel that has been refined in the melting furnace is transferred to a ladle and used with slagless or appropriate slag by using a stirrer, degasser, heating device, etc. ) Molten steel components, temperature uniformity and target, (2) Deoxidation, desulfurization, denon-metallic inclusions, decarburization, degassing, etc. of molten steel, (3) Reduction recovery of useful components in slag, etc. The finishing refining is done.
[0003]
Product quality is mainly related to refining content and level, and refining cost is strongly related to refining content and refining speed. Lower speed results in increased costs due to the need for reheating and refractory consumption. In any refining method, stirring of molten steel, slag and refining medium gas has a great influence on the refining speed.
[0004]
As a measure of stirring that affects the refining speed, a stirring energy density, that is, power E (W / ton) per unit mass of molten steel is usually used.
[0005]
On the other hand, the reaction rate coefficient k (1 / min) shown in the following equation is used as the reaction rate that forms the main part of the refining efficiency.
(C−Ce) / (Co−Ce) = exp (−k × t)
C: concentration (1/1), Ce: equilibrium concentration, Co: initial concentration, t: time (minutes)
Based on the above characteristic values E and k, the preceding examples of various stirring methods are compared and examined.
[0006]
Case (1)
Japanese Patent Publication No. 1-46563 and Document 1 disclose the following contents.
The upper part of the molten steel is strongly stirred by blowing gas into the molten steel from the bottom of the container while reducing the atmospheric pressure above the ladle to 30 to 150 torr. Since the ladle capacity is small, the stirring energy density E is 0.2 (kW / ton) and the deoxidation rate coefficient k is 0.4 (1 / min), and the refining is completed in a few minutes.
[0007]
Disadvantageously, gas bubbling under reduced pressure is extremely weak in the upper part of the molten steel in principle, but is extremely weak in the lower part because it is only agitated by the expansion and levitation of a limited amount of blown gas. ing. Therefore, there is a problem that even if the small-capacity ladle is successful, the large-capacity ladle is inconvenient.
Reference 1; The Institute of Metals; 3rd International Conference on CleanSteel, 1985, June, P.250
[0008]
Case (2)
Japanese Laid-Open Patent Publication No. 7-179927 proposes a method for optimizing processing conditions such as the amount of blown gas and atmospheric pressure in order to solve the above problems. Although this method is improved, the reaction rate in a large-capacity ladle cannot be reduced.
[0009]
Case (3)
In ASEA JOURNAL 4,1971, various methods for induction stirring of molten steel are described in detail. A type in which the moving magnetic field device is arranged on the side surface of the cylindrical ladle so that the molten steel flows upward or downward along the wall surface, and the moving magnetic field coil is coaxially arranged on the outer periphery of the ladle so that upward flow is generated along the entire circumference of the ladle wall surface. The type to give, the type which stirs by applying a pinch force to molten steel with a solenoid type single phase coil similarly, etc. are shown. In either method, an average stirring energy density E of about 0.1 (kW / ton) is likely to be obtained, and the reaction is promoted.
[0010]
One of the problems is that the slag is not directly stirred and the contact between the molten steel and the slag is laminar, so the reaction between the two phases is not strong. The second problem is a gentle and irregular flow due to a low frequency, so that the molten steel treated by the slag and the untreated molten steel are mixed gently, and the refining reaction becomes gradually decreasing. The deoxidation rate coefficient k is usually estimated to be about 0.1 to 0.2 (1 / min). Therefore, when refining by slag such as deoxidation, desulfurization, denon-metallic inclusions, etc. is the main, shortening of the refining time cannot be expected so much and reheating is required. As a result, there arises a problem of refractory corrosion due to slag.
[0011]
Case (4)
There is a so-called ASEA-SKF method, and there is a method in which the above-mentioned induction stirring device, vacuum degassing device and arc reheating device are attached to a ladle to perform high-level refining. Equivalent values of E and k are obtained.
[0012]
In this case, a basic high-grade refractory is used for the slag level of the ladle wall in order to endure refining for a long time. The refractory material has large heat conduction and heat capacity, which causes the heat loss of the molten steel and increases the reheating load. This promotes refractory corrosion. Although high quality can be obtained, in addition to equipment costs, there are significant cost problems such as refining time, electric power, electrode rods, and refractories.
[0013]
Case (5)
In JP-A-11-335719, the molten steel in a cylindrical tundish is centrifugally agitated by a horizontal rotating magnetic field while gas blowing conditions are specified to disperse fine bubbles and promote the floating separation of nonmetallic inclusions. A way to do it is presented.
[0014]
Stirring is effectively used for bubble dispersion, but the problem is that centrifugal stirring is not surprisingly high in mixing. That is, since the homogenization time is not small, it is not always effective in many refining reactions. Also, the refining action is limited to the adsorption and separation of nonmetallic inclusions by bubbles, and it is impossible to obtain other refining effects because of the single function.
[0015]
[Problems to be solved by the invention]
In order to solve the above-mentioned problems in the ladle refining process, the present invention promotes the reaction between molten steel-slag-gas-pseudo-vacuum by synergistic effect of effective induction stirring of molten metal and gas bubbling under reduced pressure. The present invention provides a refining method capable of performing various refining with high efficiency, that is, in a short time and at low cost.
[0016]
[Means for Solving the Problems]
In order to achieve the above objective, we reviewed the stirring energy density, which is the key to the reaction rate, and obtained two guidelines. For one, the known empirical relationship between the stirring energy density E and the reaction rate coefficient k (see FIG. 4) does not necessarily define the limit of the reaction rate. There seems to be a rate-limiting process and macro mass transfer to the reaction zone. The applied stirring energy does not act effectively on this mass transfer.
[0017]
Another guideline is that various conventional stirring methods are processed batch-wise in a container, and even if it seems to be regular stirring at first glance, the reaction progressing part, the already reacted part, and the unreacted part are mixed gently, so the efficiency is high. It is not a typical reaction progress. That is, from the above two points, it was noticed that there was a possibility of speeding up the reaction depending on the state of stirring, and this hypothesis was almost verified by experiments, so the following invention was constructed.
[0018]
In the first aspect of the present invention, an electromagnetic coil that generates a helical rotating magnetic field obtained by combining a rotating magnetic field and a moving magnetic field in the rotational axis direction is disposed on the outer periphery of a cylindrical metallurgical container upright and coaxially with the central axis of the container. This is a method for refining a molten metal, characterized in that spiral molten stirring is applied to the molten steel.
[0019]
According to a second invention, in the first invention, the molten metal is molten steel, the metallurgical vessel is a ladle, the direction of thrust of the spiral rotating magnetic field is downward, and a refining gas is blown into the molten steel from the bottom of the ladle. A molten metal refining method characterized by generating a bubble-containing tornado flow in the molten steel by depressurizing the upper atmosphere, and moving and promoting the lower molten steel in the ladle to the upper layer.
[0020]
According to a third invention, in the second invention, the flow rate of the refining gas is 2 to 20 N liters / minute / ton of molten steel, the atmospheric pressure is maintained at 3 to 30 kPa, and the rotational speed of the spiral rotating magnetic field is set on the inner wall surface of the ladle. It is a molten metal refining method characterized in that the speed is set to 0.5 to 20 m / sec.
[0021]
According to a fourth invention, in the first invention, the molten metal is molten steel, the metallurgical vessel is a ladle, a smelting slag is placed on the molten steel, and the smelting gas is 2 to 20 N liters / minute / molten steel ton from the bottom of the ladle. The molten steel is blown into the molten steel at a flow rate of, the atmospheric pressure above the slag is maintained at 3 to 30 kPa, the direction of thrust of the spiral rotating magnetic field is upward, the rotational speed of the vortex is 10 to 60 rpm, and the upper surface of the molten steel is parabolic A molten metal refining method characterized in that the molten steel of the lower layer in the ladle is moved and promoted to the upper layer while suppressing the contact reaction between the floating slag and the refractory on the inner wall surface of the ladle. It is.
[0022]
The fifth invention is the third or fourth invention, wherein one or more oxides of Mn, Cr, Ni, Cu, V, Nb, Mo, W, Zn, and Pb are contained in the slag for refining and reduced. One or more of C, Si, Al, Ca, CaC ₂ , and SiC as an agent is added to molten steel or slag in a substantially chemical equivalent amount to the metal oxide, and the metal is reduced and recovered. This is a method for refining molten metal.
[0023]
The sixth invention uses the fifth invention, from the molten steel containing evaporable impurities Zn, Pb, Sb, As, or from the slag containing the metal oxide, the metal This is a method for refining molten metal, characterized by evaporating and removing water.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 is a schematic side view illustrating a refining apparatus applied to the first invention.
[0025]
A cylindrical metallurgical vessel 1 lined with a refractory 2 is erected on the outer skin of a nonmagnetic steel plate to hold the molten metal 3. A general rotating magnetic field device 5 is disposed on the outer periphery of the container 1 coaxially with the central axis 4 of the container 1. When a rotating magnetic field is generated by energization, the molten metal 3 is dragged by the magnetic field to rotate, that is, eddy current. Will occur.
[0026]
At this time, when the rotating magnetic field device 5 is reciprocated up and down largely by the elevator 6, the molten steel also receives the electromagnetic force of the vertical movement. When the current is raised, the current is cut off, and when the current is lowered only, the downward spiral rotating magnetic field is generated. The molten metal 3 spirally descends along the wall surface of the container 1, reaches the bottom surface, and rises from the center of the bottom surface. The upper layer portion is sequentially drawn to the periphery to form a circulating flow 7 throughout the container. Although the circulating flow 7 is not necessarily regular and stable, the added stirring energy is not wasted much in the local mixing, and each part of the molten metal is effectively transferred to the upper layer part which is the main reaction region.
[0027]
Although the generation method of the spiral rotating magnetic field can be considered in addition to this, it is only illustrated.
[0028]
FIG. 2 is a schematic side view illustrating the structure of an apparatus applied to the refining method of the second invention. The second invention is an example in which the first invention is applied to ladle refining, in which a molten steel 13 is held in a cylindrical ladle 11 formed of an airtight and non-magnetic iron skin, and an electromagnetic wave that generates a spiral rotating magnetic field is generated. A coil 15 is arranged on the outer periphery of the ladle 11 coaxially with the ladle central shaft 14 and energized to give spiral stirring to the molten steel 13.
[0029]
On the other hand, the refining atmosphere can be maintained at a predetermined pressure by sealing the ladle 11 with the vacuum cover 17 provided with the exhaust pipe 16 and exhausting the space inside the ladle with the vacuum pump 18.
[0030]
When a refining gas such as Ar gas is blown into the molten steel 13 through the refractory vent plug 19 from the bottom surface of the ladle 11 at an appropriate flow rate, the rising bubbles are subjected to the action of spiral rotation stirring and the center axis of the ladle A tornado flow (tornado-like vortex) is formed in the periphery, and becomes a strong upward flow, and the circulation flow 7 by spiral rotation stirring is stably strengthened.
[0031]
The molten steel and slag surfaces that are in a boiling state due to gas blowing are foamed as the appearance changes when the atmospheric pressure is lowered by the operation of the vacuum pump. There, a four-phase mixed zone 21 of bubble-slag-molten steel-pseudo-vacuum is formed by severe disturbance.
[0032]
In accordance with the refining treatment conditions, various reactions such as deoxidation, desulfurization, denon-metallic inclusions, degassing, and reduction proceed rapidly in the mixing zone 21. As is well known, for slagless, degassing, for non-oxidizing basic slag, for deoxidation / desulfurization, for acidic slag, for de-non-metallic inclusions, for reducing slag, If there is, effective refining progresses for the reduction and recovery of useful metal oxides.
[0033]
FIG. 3 is a schematic side view illustrating the structure of an apparatus applied to the refining method of the fourth invention. The fourth invention is the one in which the thrust direction of the spiral rotation stirring is reversed upside down in the second invention, and a strong tornado flow is hardly formed, but a circulating flow 7 'is formed. Similarly, the foaming phenomenon of the upper part of the molten steel is accompanied.
[0034]
If the stirring conditions such as the position of the electromagnetic coil, magnetic flux density, rotation speed, thrust, etc. are set appropriately, the upper surface of the molten steel will collapse into a parabolic surface due to strong eddy currents, and the slag with a lower density than the molten steel will be centered by the difference in centrifugal force. Be drawn to. The stirring method is effective when it is desired to suppress the slag / refractory contact reaction.
[0035]
When carrying out the third and fourth inventions, an oxide of an alloying element having a relatively low affinity for oxygen such as Cr and V and a reducing agent such as C and Si in an amount equivalent to chemical equivalents are contained in the molten steel or slag. In addition, the oxide is rapidly reduced and recovered almost entirely in the molten steel.
[0036]
As in the previous section, when electric furnace steelmaking dust that is industrial waste is added, Zn, Pb, etc. contained in a large amount in the dust are rapidly reduced and evaporated by C, Si, etc. in the molten steel.
[0037]
The steam is guided to the dust collector 22 while being oxidized in the middle of the exhaust pipe 16, and can be recovered there as a high concentration oxide.
[0038]
[Action]
It will be explained next that an appropriate spiral flow is very effective for the refining reaction. The flow and mixing conditions were observed by a water model using a transparent cylindrical vessel and a rotating stirring blade. In the case of a simple vortex, the ink diffuses concentrically regardless of where the ink is dropped, but it is surprisingly slow to homogenize.
[0039]
When the spiral guide vanes were partially attached to the inner surface of the container, an upward or downward spiral flow was easily obtained depending on the direction of rotation. A relatively stable and regular circulation flow was observed in which the cylindrical core and the peripheral part were upside down. In this case, the ink and suspension were rapidly homogenized. The first invention was constructed based on this fact.
[0040]
When gas was blown into the simple vortex inside the cylinder from the bottom, a spiral flow was recognized by the combination of rotation and rise, and a circulation flow with the core up and the periphery down was also obtained. At the same time, although it was unstable, generation of bubble-containing tornado was observed depending on the situation.
[0041]
When gas was blown in from the bottom of the cylinder while stirring downward with a spiral guide blade, the bubble-containing tornado and the circulation flow were stably maintained.
[0042]
Next, when the pressure above the liquid level is reduced, the liquid level rises rapidly and changes from a boiling state to a foaming state, and the boundary surfaces of the gas phase, the liquid phase, and the bubbles become unclear, and the intensity of the disturbance is increased. It was observed that the tornado and the circulation flow were maintained. The second invention is configured based on this observation fact.
[0043]
Next, the stirring energy is examined. The refining gas blown forms bubbles on the plug 19 and immediately rises in temperature and expands to generate initial stirring energy. Next, the second agitation kinetic energy due to the rising of the bubbles and the gentle expansion, when approaching just below the liquid level, the third agitation energy is generated due to the rapid expansion due to the rapid decrease of the bubble external pressure (= static pressure of molten steel + atmospheric pressure).
[0044]
As described above, most of the various reactions themselves proceed in the four-phase mixing zone 20 of bubbles / slag / molten steel / pseudo-vacuum in a foamed / disturbed state, and as is well known, the speed of the reaction itself is extremely high. This results from a sufficient amount of the third agitation energy. On the other hand, the fact that the overall reaction rate increases as the stirring energy increases in various processes suggests that the mass transfer to the reaction region is rate limiting.
[0045]
As explained in the preceding case (2), in the gas bubbling under a reduced pressure, the first and second stirring energy amounts are usually not sufficient with respect to the third stirring energy amount. 1st invention reinforces the said 1st, 2nd stirring energy.
[0046]
The manner in which the stirring energy works as well as the amount of stirring energy is important. That is, it is desirable that the stirring energy applied outside the mixing zone is mainly consumed for the mass transfer. For this purpose, it is necessary that the stirring energy is not consumed for local disturbance and a large stable circulation flow is formed. The first invention not only strengthens the stirring energy, but also embodies a mechanism by which the added stirring energy effectively acts on mass transfer through the formation of a circulating flow.
[0047]
Next, the grounds for specifying the processing conditions in the third and fourth inventions will be described. The refining gas flow rate was set to 2 to 20 N liter / minute / molten steel ton. The action force was insufficient if it was less than 2 N liter / minute / molten steel ton. It is because it becomes easy to generate | occur | produce.
[0048]
The atmospheric pressure of 3 to 30 kPa is advantageous for degassing if it is less than 3 kPa, but a steam ejector is required as an exhaust device, which is disadvantageous in terms of energy cost. Above 3 kPa, various pumps that are cost-effective for both equipment and operation can be used. If it exceeds 30 kPa, the effect of gas bubbling under reduced pressure is reduced.
[0049]
The reason for specifying the rotational speed of the spiral rotating magnetic field so that the peripheral speed on the outer peripheral surface of the molten steel is 0.5 to 20 m / min is that the induced electromagnetic force is small when the relative speed of the induced conductor, that is, the molten steel and the moving magnetic field is small. On the other hand, if it is large, it is consumed as induction heating in the skin or molten steel skin due to the skin effect, and the electromagnetic force becomes small. Based on the fact that the above range is generally practical from examples and experiments.
[0050]
The reason why the rotational speed of the vortex is specified as 10 to 60 rpm in the fourth invention is as follows. When the strength of the spiral flow exceeds a certain limit, a vortex flow is formed. The shape of the vortex surface is a paraboloid. The depth of the depression is proportional to the square of the product of the inner diameter of the container and the number of revolutions, based on the forced vortex equation. The vortex causes the slag covering the surface of the molten metal to face away from the refractory wall. This is because, at 10 rpm or less, the depression depth is 0.2 m or less even in a large ladle, the centripetal force of the slag is weak, and the slag does not separate from the wall refractory. This is because even at a small ladle above 60 rpm, the vortex depth exceeds 1 m, and the danger increases.
[0051]
The fifth invention effectively implements the powerful reduction refining ability that is not possessed by the methods of case (1) and case (2) but potentially possesses, that is, reduction and recovery of useful element oxides. It has become. As is well known, the mass transfer from the slag to the molten steel / slag interface is rate-limiting in the reduction reaction of the oxide in the slag. Gas bubbling under reduced pressure is very convenient for molten steel / slag disturbance, and the addition of a circulating flow by electromagnetic force allows efficient processing from reduction to finishing.
[0052]
Examples of elements to be reduced include Mn, Cr, Ni, Cu, V, Nb, Mo, W, Zn, and Pb. Since Zn and Pb have a high vapor pressure at the steelmaking temperature, they are not recovered in the molten steel, but are discharged out of the system as steam and recovered by, for example, the dust collector 22. As the reducing agent, C, Si, Al, Ca, CaC ₂ , SiC and the like are practical.
[0053]
When a large amount of low-grade scrap is used as the iron source, impurities such as Zn, Pb, Sb, As, etc. remain in the molten steel, and their oxides remain in the slag and increase, resulting in a decrease in quality. 4 is removed by reduction and evaporation.
[0054]
【Example】
Experiment 1 (Verification of the third invention)
The same ladle with a capacity of 30 tons was used for high carbon steel, and the method of the case (1) was compared with the method of the present invention as a comparative example for the deoxidation rate coefficient. The treatment conditions and results of the comparative example of several tens of charges are as follows: the temperature at the time of receiving steel from the melting furnace is 1570 to 1590 ° C., non-oxidizing basic slag is placed on the non-deoxidized molten steel, and the dissolved oxygen amount is 65 -85 ppm, atmospheric pressure is about 14-21 kPa, Ar gas blowing rate is 150-200 Nl / min, treatment time is 3-9 minutes. The amount of dissolved oxygen at the end of refining was 18 to 32 ppm, the molten steel temperature was 1535 to 1540 ° C., and the deoxidation rate coefficient k was 0.36 (1 / min) on average.
[0055]
The downward spiral rotating stirring of the present invention was applied under the same conditions as described above. A dipole rotating magnetic field having an input of 160 kVA and a frequency of 1 Hz was applied to the lower third region of the ladle. Since accurate calculation or actual measurement of the electromagnetic force is difficult, the stirring energy density was estimated to be about 0.2 kW / ton from the magnetic flux density distribution measurement value and the magnetic field moving speed. The treatment time is 2.5 to 6.0 minutes, the dissolved oxygen amount at the end is 13 to 24 ppmm, the molten steel temperature is 1540 to 1550 ° C., and the deoxidation rate coefficient k is increased to about 0.5 to 0.7 for refining. Efficiency improved. By increasing the deoxidation rate coefficient, not only deoxidation but also the foundation for efficiency improvement is established for desulfurization and other refining.
[0056]
Experiment 2 (Verification of the fourth and fifth inventions)
For spring steel, under the same conditions as in Experiment 1, both put ore with Cr ore equivalent to 1.0% for Cr and 0.15% equivalent for V for V at the time of steel production. The chemical equivalent of Fe-Si powder required for the reduction of Cr and V was added.
[0057]
In both cases, the Cr concentration in the slag decreased from about 30% in the initial stage to 0.4 to 0.7%, and the reduction and recovery of Cr was sufficient, but it took 8 minutes or more in the comparative example, and within 5 minutes in the present invention. I was able to handle it.
[0058]
Experiment 3 (Verification of the sixth invention)
As above, confirmation and comparison of the Zn removal reaction were performed. In the electric furnace melting process, electric furnace dust was inserted by about 1% of the molten steel amount. The composition of the dust is about 25% for ZnO and about 55% for FeO. In the comparative example, Zn is 0.01 to 0.03% in the slag after ladle refining, and 10 to 30 ppm remains in the molten steel. In the present invention, 0.01 to 0.02% and 8 to 16 ppm remain, respectively. Zn was made efficiently.
[0059]
【The invention's effect】
According to the present invention, in the first invention, a helical electromagnetic induction stirring flow along the inner surface of the cylinder is generated in the molten metal in the cylindrical container, so that the mass transfer from the non-reaction region to the reaction region is promoted, and the various refining reactions To promote. In the second invention, a circulating flow with a bubble-containing tornado flow acts synergistically in the region of intense contact reaction between gas, slag, molten steel and pseudo-vacuum due to the interaction of downward spiral flow and gas bubbling under reduced pressure. To promote further refining reactions. The third invention presents the specific conditions of the second invention. When the fifth invention is used, the oxide of the alloy element such as Cr ore added to the slag is reduced and recovered at a high speed and with a high yield, and the refractory melts less, which is advantageous in terms of cost. In the sixth invention, harmful oxides such as Zn in molten steel or slag are easily removed by evaporation. This effect is extremely effective in terms of cost, for example, by expanding the use of low-grade scrap and enabling melting treatment of electric furnace dust that is an industrial waste.
[Brief description of the drawings]
FIG. 1 is a schematic side view illustrating a refining apparatus applied to the first invention.
FIG. 2 is a schematic side view illustrating a refining apparatus applied to the second invention.
FIG. 3 is a schematic side view illustrating a refining apparatus applied to the third invention.
FIG. 4 is a diagram showing the relationship between stirring energy density E and deoxidation rate coefficient k.
[Explanation of symbols]
1: Metallurgical vessel 2: Refractory material 3: Molten metal 4: Central shaft 5: Rotating magnetic field device 6: Elevator 7, 7 ': Circulating flow 11: Ladle 13: Molten steel 14: Central shaft 15: Electromagnetic coil 16: Exhaust pipe 17 : Vacuum cover 18: Vacuum pump 19: Ventilation plug 20: Tornado flow 21: Four-phase mixing zone 22: Dust collector

Claims (6)

An electromagnetic coil that generates a helical rotating magnetic field that combines a rotating magnetic field and a moving magnetic field in the rotational axis direction is placed on the outer periphery of a cylindrical metallurgical vessel upright and coaxial with the central axis of the vessel to spirally stir the molten metal in the vessel. A method for refining molten metal, characterized in that: The molten metal is made into molten steel, the metallurgical vessel is made into a ladle, the direction of the thrust of the spiral rotating magnetic field is made downward, and a refining gas is blown into the molten steel from the bottom of the ladle, and the atmosphere above the molten steel is reduced in pressure. 2. The method for refining molten metal according to claim 1, wherein a bubble-containing tornado flow is generated in the ladle, and the lower molten steel in the ladle is moved and promoted to the upper layer. The flow rate of the refining gas is 2 to 20 N liters / minute / ton of molten steel, the atmospheric pressure is maintained at 3 to 30 kPa, and the rotational speed of the spiral rotating magnetic field is 0.5 to 20 m / second on the inner wall surface of the ladle. The molten metal refining method according to claim 2, wherein the setting is performed as follows. A molten metal is used as a molten steel, a metallurgical vessel is used as a ladle, a smelting slag is placed on the molten steel, and a smelting gas is blown into the molten steel from the bottom of the ladle at a flow rate of 2 to 20 Nliters / minute / toned steel. The upper atmospheric pressure is maintained at 3 to 30 kPa, the direction of thrust of the spiral rotating magnetic field is set upward, the rotational speed of the vortex is set to 10 to 60 rpm, the molten steel upper surface is depressed into a parabolic shape, and the slag floating 2. The molten metal refining method according to claim 1, wherein the molten steel in the lower layer in the ladle is moved and promoted to the upper layer while suppressing a contact reaction between the steel and the refractory on the inner wall surface of the ladle. One or more oxides of Mn, Cr, Ni, Cu, V, Nb, Mo, W, Zn, and Pb are contained in the slag for refining, and C, Si, Al, Ca, CaC ₂ , SiC as a reducing agent 5. The refining of molten metal according to claim 3, wherein one or more of the above are added to molten steel or slag in a substantially chemical equivalent amount to the metal oxide to reduce and recover the metal. Method. The metal is evaporated and removed from the molten steel containing evaporable impurities such as Zn, Pb, Sb, As or from the slag containing the metal oxide by the method of claim 3 or claim 4. A method for refining molten metal characterized by the above.

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