JP2017115243A - Stirring method of molten metal, stirring apparatus, desulfurization method and desulfurization apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably enhance stirring ability for molten metal or to stably enhance reaction efficiency in desulfurization process by stably enhancing the stirring ability.SOLUTION: With a stirring apparatus (for example, a desulfurization apparatus 14) which comprises: a rotational axis 3 which is arranged in an extending manner in a height direction of a container 16 storing molten metal and is rotatably arranged on its axis in the height direction; and a rotator 7b which is connected coaxially with the rotational axis 3 on a lower edge or between the lower edge and upper edge in an extending direction of the rotational axis 3, is rotated due to rotation of the rotational axis 3, is communicated with a suction port 12 at an inner section, and comprises ejection ports 13a to 13h arranged more outside than the suction port 12 relatively to the rotational axis of the rotational axis 3 on its surface, the rotator 7b is immersed into the molten metal stored in the container 16 and the rotator 7b is rotated by rotation of the rotational axis 3 so as to stir the molten metal.SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a molten metal stirring method, a stirring device, a desulfurization method, and a desulfurization device.

  In recent years, the demand for high-quality steel such as extremely low phosphorus and extremely low sulfur has been increased from the viewpoint of improving material properties accompanying the increase in added value of steel and the expansion of usage of steel materials. In order to meet these quality requirements, in the steelmaking process for refining molten steel, it is required to melt the steel according to these quality requirements without causing an increase in production cost and slag generation. For this reason, in the refining process of a steelmaking process, it is indispensable to raise the reaction efficiency of refining agents, such as a dephosphorizing agent and a desulfurizing agent, and hot metal. In addition, in order to respond to the recent increase in steel demand, it is necessary to improve productivity, and it is also important to improve the reaction rate in the refining treatment of hot metal and molten steel.

  Conventionally, hot metal desulfurization processing methods using a mechanical stirring type desulfurization apparatus have been widely put into practical use as a technology that meets these requirements. In this desulfurization treatment method, an impeller (also referred to as “rotary blade” or “stirring blade”) is immersed in hot metal and rotated to strongly stir the hot metal and the desulfurizing agent. As a result, even if an inexpensive desulfurizing agent mainly composed of CaO (lime) (hereinafter referred to as “CaO-based desulfurizing agent”) is used, the sulfur concentration is low from 0.002 to 0.004 mass%. It is possible to desulfurize the hot metal in a short time to the region.

  In the hot metal desulfurization treatment in the mechanical stirring type desulfurization equipment using the CaO-based desulfurizing agent, the powdered or granular CaO-based desulfurizing agent added to the surface of the molten iron is contained in the hot metal vortex formed by the rotation of the impeller. Get involved in. Thereby, the contact interface area of a CaO type | system | group desulfurization agent and hot metal becomes large, and the reaction efficiency of a CaO type | system | group desulfurization agent can be improved. At this time, the hot metal is stirred by the rotation of the impeller, and the sulfur in the hot metal is sequentially supplied to the reaction interface (desulfurization agent surface), whereby the desulfurization reaction proceeds. In general, the reaction container for containing the hot metal is a pan-shaped cross section, and an impeller is inserted from above at the substantial center of the reaction container.

  However, it has become difficult to respond to the recent increase in demand for ultra low-sulfur steel by the conventional technology alone. Therefore, as a technique for further improving the reaction efficiency of the CaO-based desulfurization agent and further shortening the processing time in the hot metal desulfurization processing method in the mechanical stirring desulfurization apparatus, the impeller is screwed, the impeller is eccentrically inserted, the reaction vessel Techniques have been proposed to improve the stirring ability by installing baffles on the screen.

  For example, in Patent Document 1, the thickness of the refractory to be applied to the bottom of the reaction vessel is changed so that the inner surface shape of the bottom of the reaction vessel containing hot metal is not axially symmetric with respect to the central axis of the reaction vessel. A desulfurization method has been proposed. According to the desulfurization treatment method described in Patent Document 1, the vortex formed by the rotation of the impeller is decentered, and the stirring ability is improved by promoting the inclusion of the CaO-based desulfurization agent in the hot metal.

  Further, in Patent Document 2, the vortex formed by the rotation of the impeller is decentered by decentering the insertion position of the impeller from the center of the reaction vessel, and further, the powdered CaO system from the dedicated lance to the formed vortex. A desulfurization treatment method in which a desulfurizing agent is sprayed together with a carrier gas has been proposed. According to the desulfurization processing method described in Patent Document 2, since the forced turbulence is generated in the rotating flow due to the eccentricity of the vortex, the stirring ability is improved and the high reaction efficiency by the CaO-based desulfurizing agent is realized. be able to.

JP 2011-26696 A JP 2011-42815 A

  However, in the desulfurization treatment method described in Patent Document 1, the difference in height of the bottom of the reaction vessel provided by the difference in height of the refractory is reduced by the wear of the refractory, so that the effect of improving the stirring ability is maintained over a long period of time. There is a problem that you can not. In particular, when the cold iron source is pre-charged into the reaction vessel, this problem becomes significant because the wear of the bottom refractory due to the pre-charged cold iron source becomes severe.

In addition, the desulfurization treatment method proposed in Patent Document 2 has a problem in that it is difficult to adjust the positional relationship between the reaction vessel and the impeller, so that a stable stirring ability cannot be improved. When the impeller insertion position deviates from the target, the desulfurization efficiency is lowered, so that a re-desulfurization process may be necessary, which may cause a reduction in hot metal temperature and a decrease in productivity.
The present invention has been made in view of the above-described problems, and in the desulfurization treatment by stably increasing the stirring method and stirring apparatus of the molten metal, or stably increasing the stirring ability of the molten metal. An object of the present invention is to provide a molten metal desulfurization method and a desulfurization apparatus capable of stably increasing the reaction efficiency.

  According to one aspect of the present invention, the rotating shaft is provided so as to extend in the height direction of the container containing the molten metal and is provided to be rotatable around its own axis in the height direction, and the rotating shaft. Is connected concentrically with the rotating shaft between the lower end or the lower end and the upper end in the direction in which the rotating shaft extends, rotates by rotation of the rotating shaft, communicates with the inside of the suction port and the suction port, The rotating body is immersed in the molten metal accommodated in the container by using a stirring device including a rotating body having a discharge port provided on the surface with respect to the rotating shaft on the surface of the discharge port. A molten metal stirring method is provided, wherein the molten metal is stirred by rotating the rotating body by rotating a rotating shaft.

  According to one aspect of the present invention, the rotating shaft is provided so as to extend in the height direction of the container containing the molten metal and is provided to be rotatable around its own axis in the height direction, and the rotating shaft. Is connected concentrically with the rotating shaft between the lower end or the lower end and the upper end in the direction in which the rotating shaft extends, rotates by rotation of the rotating shaft, communicates with the inside of the suction port and the suction port, There is provided a molten metal stirring device comprising: a rotating body having a discharge port provided on an outer surface of the rotating shaft with respect to a rotating shaft.

  According to one aspect of the present invention, the rotating shaft is provided so as to extend in the height direction of the container containing the molten metal and is provided to be rotatable around its own axis in the height direction, and the rotating shaft. Is connected concentrically with the rotating shaft between the lower end or the lower end and the upper end in the direction in which the rotating shaft extends, rotates by rotation of the rotating shaft, communicates with the inside of the suction port and the suction port, The rotating body is immersed in the molten metal accommodated in the container by using a stirring device including a rotating body having a discharge port provided on the surface with respect to the rotating shaft on the surface of the discharge port. The rotating body is rotated by rotating a rotating shaft to stir the molten metal, and a CaO-based desulfurizing agent is added to the molten metal during the stirring of the molten metal using the stirring device. A method for desulfurizing molten metal is provided.

  According to one aspect of the present invention, the rotating shaft is provided so as to extend in the height direction of the container containing the molten metal and is provided to be rotatable around its own axis in the height direction, and the rotating shaft. Is connected concentrically with the rotating shaft between the lower end or the lower end and the upper end in the direction in which the rotating shaft extends, rotates by rotation of the rotating shaft, communicates with the inside of the suction port and the suction port, A rotating body having a discharge port provided outside the suction port with respect to the rotating shaft, and a charging unit for charging a CaO-based desulfurizing agent into the molten metal accommodated in the container. A molten metal desulfurization apparatus is provided.

  According to one embodiment of the present invention, the reaction efficiency in the desulfurization treatment can be stably increased by stably increasing the stirring ability of the molten metal or by stably increasing the stirring ability.

It is a schematic diagram which shows the stirring apparatus in a water model experiment. It is the top view and front view which show an impeller. It is the top view and front view which show a rotary body. It is the II arrow directional view of FIG. It is a graph which shows the relationship between the torque in a water model experiment, and uniform mixing time. It is a graph which shows the relationship between the ratio of the dent depth with respect to the discharge flow rate and bath diameter in a water model experiment. It is a graph showing the relationship between _{^{a 2 · d · n P ·}} N-0.62 × H / D and winding number of the water model experiment. It is a mimetic diagram showing a desulfurization device concerning one embodiment of the present invention. It is sectional drawing which shows the modification of a rotary body. It is a graph which shows the relationship between the torque ratio in an Example, and a desulfurization rate. Is a graph showing the relationship between _{^{a 2 · d · n P ·}} N-0.62 × H / D and desulfurization rate in the embodiment.

  In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

<Water model experiment>
As a result of repeated investigations on the method of increasing the stirring capacity and increasing the reaction efficiency between hot metal and a CaO-based desulfurizing agent in the hot metal desulfurization treatment method in the mechanical stirring desulfurization apparatus, the present inventors have found that the stirring unit is immersed in hot metal. Further, it has been found that more energy can be given to the hot metal by providing a suction port and a discharge port, which will be described later. Details of the examination are shown below.
The present inventors conducted a water model experiment using the stirring apparatus 1 simulating an actual machine shown in FIGS. 1 to 4 and confirmed the difference in stirring behavior due to the difference in the shape of the stirring section. As shown in FIG. 1, the stirring device 1 includes a cylindrical container 2, a rotating shaft 3, a rotating motor 4, a rotation speed control panel 5, a torque meter 6, and a stirring unit 7.

  The cylindrical container 2 is a bottomed cylindrical container, and contains water 8 imitating hot metal inside. The diameter of the bottom of the inner surface of the cylindrical container 2 was 350 mm. The rotating shaft 3 is a rod-like body that extends in the height direction of the cylindrical container 2 (vertical direction with respect to the paper surface of FIG. 1). The rotation motor 4 is a motor connected to the upper end side of the rotary shaft 3, and rotates the connected rotary shaft 3 around the axis of the rotary shaft 3. The rotation speed control panel 5 is a control device that is electrically connected to the rotation motor 4 and controls the rotation speed of the rotary shaft 3 by controlling the rotation motor 4. The torque meter 6 is provided on the upper end side of the rotating shaft 3 and measures the torque of the rotating rotating shaft 3. The stirring unit 7 is connected and fixed to the lower end of the rotating shaft 3 concentrically with the rotating shaft 3. In the water model experiment, two types of stirring sections 7a and 7b (7) having different shapes as shown in FIGS.

  The stirring unit 7 shown in FIG. 2 is an impeller 7a, and imitates a shape generally used in a mechanical stirring type desulfurization apparatus. The impeller 7 a is fixed to the rotating shaft 3 by connecting the lower end of the rotating shaft 3 and the hole-shaped connecting portion 9. Further, as shown in FIG. 2, the impeller 7 a includes four blades 10 having the same shape that extend in the height direction in which the rotation shaft 3 extends and project from the rotation shaft 3 in a direction perpendicular to the height direction. Have Four blades 10 are adjacent to each other at right angles. The impeller 7a has a length of 50 mm in the height direction, a length from one end to the other end in the direction perpendicular to the height direction of the two facing blades 10, and a thickness of the blade 10 of 25 mm. It was.

  3 and 4 is a rotating body 7b according to an embodiment of the present invention. The rotating body 7b has a cylindrical shape, and a hole-like connecting portion 11 connected to the lower end of the rotating shaft 3 is formed at the center of the upper surface, which is the upper end in the height direction, like the impeller 7a. Further, the impeller 7a has a suction port 12 and eight discharge ports 13a to 13h. The suction port 12 is formed in an annular shape around the connection portion 11 on the upper surface of the rotating body 7b. Furthermore, a groove extending in the height direction from the suction port 12 is formed in the rotating body 7b. The eight discharge ports 13a to 13h are respectively formed in a circle on the side surface between the upper and lower surfaces, which are the upper and lower ends of the rotating body 7b, at equal intervals in the circumferential direction of the rotating body 7b. The eight discharge ports 13 a to 13 h extend from the side surface of the rotating body 7 b toward the connection portion 11 and communicate with the groove of the suction port 12. That is, the suction port 12 and the eight discharge ports 13a to 13h communicate with each other inside the rotating body 7b. The dimensions of the rotating body 7b were 30 mm in the height direction, 120 mm in length perpendicular to the height direction, and 20 mm in diameter in the cross section of the eight discharge ports 13a to 13h.

  In the water model experiment, the stirring unit 7 is immersed in the water 8 accommodated in the cylindrical container 2, and a 2 mm diameter sphere made of vinyl chloride imitating a molten metal refining agent is floated on the water 8 on the surface of the water 8. Oita. The depth d1 (mm) from the bottom of the cylindrical container 2 to the bath surface of water 8 in a stationary state, and the immersion depth h (mm) from the bath surface to the upper end of the stirring unit 7 at this depth d1. The stirrer 7 was immersed so as to be 100 mm or 200 mm. And the water 8 was stirred by rotating the rotating shaft 3 and the stirring part 7 changing the rotation speed into 50 rpm-400 rpm. At this time, five photographs were taken every 15 seconds from the start of stirring, the number of spheres invading into the water 8 was counted, and the average number of spheres in the five photographs was taken as the number of entrainment. Further, from the depth d1 in a stationary state, a vortex recess depth H (mm) obtained by subtracting the depth d2 (mm) of the central portion of the bath surface during stirring measured from the photographed photo was calculated. Further, the torque applied to the rotation motor 4 during stirring was measured using a torque meter 6.

  Further, in order to measure the time required for the water 8 in the cylindrical container 2 to be uniformly mixed (hereinafter, uniform mixing time), an electric conductivity detection cell is fixed on the inner wall side of the bottom of the cylindrical container 2, and the water 8 60 ml of a 20% KCl solution was added to a place farthest away from the cell for detecting electric conductivity on the bath surface at a linear distance. Then, the measurement was started from the time when the KCl solution was added, and the time until the time when the electrical conductivity reached equilibrium was measured as the uniform mixing time.

  FIG. 5 shows the relationship between torque and uniform mixing time under two conditions where the stirring unit 7 is different. As shown in FIG. 5, it was confirmed that the uniform mixing time was reduced when the rotating body 7b was used with the same torque. This is because, in addition to the force physically pushed out by the main body of the rotating body 7b or the force of stirring the water by the resistance of the surface of the rotating body 7b, centrifugal force acts on the water that has entered the inside of the rotating body 7b. It shows that the rotating body 7b has improved stirring ability compared to the impeller 7a. Moreover, when the same stirring part 7 was used, it was confirmed that uniform mixing is short, so that the immersion depth h is large. This is because the horizontal flow formed by the stirring unit 7 collides with the bath wall and changes to a vertical flow, so that when the water 8 below the stirring unit 7 is stirred, the stirring unit 7 is immersed. This is because the larger the depth, the better the stirring at the bottom of the container.

  Next, among the results of using the rotating body 7b, it was confirmed that the number of entrainment was increased when the dent depth H of the vortex was larger than the immersion depth h of the rotating body 7b. This is because the vortex dent depth H increases, so that the sphere floating on the bath surface is easily sucked into the suction port 12, and the discharge flow from the discharge ports 13 a to 13 h approaches the bath surface. This is because the agitation force increases and the sphere is easily caught in water.

FIG. 6 shows the relationship between the discharge flow rate and the vortex recess depth H when the rotating body 7b is used. In FIG. 6, the vertical axis is a value obtained by dividing the vortex recess depth H by the bath diameter which is the diameter of the cylindrical container 2, and the horizontal axis is the discharge flow rate Q. The discharge flow rate Q (Nm ³ / s) is calculated by the following equation (1). In the formula (1), a is the diameter (mm) of the discharge ports 13a to 13h, n _p is the number (pieces) of the discharge ports 13a to 13h, ω is the angular velocity (rad / s), and N is the number of rotations of the rotating shaft 3. (Rpm) is shown respectively.

  From FIG. 6, it was confirmed that the discharge flow rate determined from the shape of the rotating body 7 b and the vortex recess depth H have a relationship represented by the following equation (2). In the equation (2), d represents the diameter (mm) of the rotating body 7b, H represents the dent depth (mm), and D represents the diameter (mm) of the cylindrical container 2.

Furthermore, the stirrability can be further improved by making the dent depth H of the vortex larger than the immersion depth h of the rotating body 7b as described above. FIG. 7 shows a graph in which a ² · d · n _P · N−0.62 × H / D is taken as the horizontal axis and the number of spheres involved is taken as the vertical axis. As shown in FIG. 7, it was confirmed that the number of spheres involved increased under the condition that the value on the horizontal axis was 0 or more. That is, by satisfying the following formula (3) for various conditions such as the shape of the rotating body 7b and the stirring conditions, the dent depth H of the vortex becomes larger than the immersion depth h, and higher stirring ability is achieved. It was confirmed that it can be obtained.

<Desulfurization equipment (stirring equipment)>
The present invention has been made based on the examination results of the water model experiment and the like. Hereinafter, the configuration of the molten metal desulfurization apparatus 14 according to an embodiment of the present invention will be described. The molten metal desulfurization apparatus 14 according to this embodiment is a refining apparatus that removes sulfur components from the molten metal 15 that is a molten metal, and is also a stirring apparatus that agitates the molten metal 15. As shown in FIG. 7, the desulfurization device 14 includes a rotating shaft 3, a rotating body 7 b that is a stirring unit 7, a container 16, a carriage 17, and a charging chute 18.

  The rotating shaft 3 and the rotating body 7b are members having similar shapes, although the dimensions are different from those of the water model experiment shown in FIGS. That is, the rotating shaft 3 extends in the height direction of the container 16, and the rotating body 7b is connected to the lower end. The rotating body 7b includes a suction port 12 provided on the upper surface and eight discharge ports 13a to 13h communicating with the suction port 12 inside. The rotary shaft 3 and the rotating body 7b are lined with a refractory material on the surface.

The container 16 is a container such as an iron hot metal ladle whose inner surface is lined with a refractory. The charging chute 18 has a tip arranged above the bath surface of the hot metal 15 and is added with auxiliary materials such as a CaO-based desulfurizing agent 19 cut out from a raw material hopper (not shown) and used refractories (not shown) on the bath surface. This is the input means. A used refractory is a refractory that has been previously crushed and adjusted in particle size.
Furthermore, the desulfurization device 14 includes equipment such as an elevator (not shown), a rotation device, a dust collection hood, an exhaust duct, and a dust collector. The lifting device lifts and lowers the rotating shaft 3 in the height direction. The rotating device rotates the rotating shaft 3 and the rotating body 7b at a predetermined rotational speed by rotating the rotating shaft 3 about the longitudinal axis of the rotating shaft 3. The dust collection hood is provided above the container 16 so as to cover the opening at the upper end in the height direction of the container 16. The dust collector sucks the exhaust gas and dust being processed through an exhaust duct provided through the dust collection hood.

<Desulfurization method (stirring method)>
In the desulfurization apparatus 14 having the above configuration, the hot metal 15 is desulfurized using the following stirring method and desulfurization method. First, the container 16 containing the hot metal 15 is placed on the carriage 17. Next, the carriage 17 moves to a position where the container 16 and the rotation shaft 3 are concentric. Furthermore, the rotating shaft 3 and the rotating body 7b are lowered and immersed in the hot metal 15 until the rotating body 7b reaches a predetermined immersion depth h by the lifting device. Thereafter, the rotating shaft 3 and the rotating body 7b are rotated by the rotating device, whereby the hot metal 15 is stirred. Next, auxiliary materials such as a CaO-based desulfurizing agent 19 and used refractory are charged into the hot metal 15 being stirred by the rotating body 7b through the charging chute 18. Furthermore, the desulfurization process is completed by stirring the rotating body 7b for a predetermined time.
In such a desulfurization method, in this embodiment, when the hot metal 15 is agitated by the rotating body 7b, it is preferable that the agitation is performed under conditions satisfying the expression (3) in order to increase the agitation ability.

<Modification>
Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. From the description of the invention, other embodiments of the invention will be apparent to persons skilled in the art, along with various variations of the disclosed embodiments. Therefore, it is to be understood that the claims encompass these modifications and embodiments that fall within the scope and spirit of the present invention.

  For example, in the above embodiment, the suction port 12 and the discharge ports 13a to 13h are provided in the columnar rotating body 7b in the arrangement shown in FIG. 3, but the present invention is not limited to such an example. The rotator 7b may have another shape as long as the molten iron 15 is sucked from the suction port 12 and the sucked molten metal 15 is discharged from the discharge ports 13a to 13h by its own rotating operation. In this case, the discharge ports 13a to 13h need to be arranged outside the suction port 12 with respect to the axis around which the rotating body 7b rotates. Therefore, for example, as shown in FIG. 9, the suction port 12 may be provided on the lower surface side of the rotating body 7 b. Further, the number of suction ports 12 and the discharge ports, and the shapes and dimensions thereof are not limited to the above-described embodiment as long as they have sufficient stirring ability and strength that can withstand practical use.

  In the above embodiment, the molten metal is the hot metal 15. However, the present invention is not limited to this example. For example, when the purpose is desulfurization treatment, the molten metal may be molten steel. Furthermore, when aiming at stirring, the molten metal may be a metal other than iron. According to the present invention, even if other metals are used, the stirring ability can be improved. Therefore, effects such as reaction promotion by stirring and shortening of uniform mixing time can be obtained.

Furthermore, in the said embodiment, when performing desulfurization process, it was supposed that auxiliary materials, such as a CaO type | system | group desulfurization agent, were added, but this invention is not limited to this example. For example, as a charging means for charging a secondary raw material such as a CaO-based desulfurizing agent, a charging device for adding the secondary raw material by blowing the secondary raw material together with the carrier gas to the hot metal 15 may be used.
Furthermore, in the said embodiment, although the rotary body 7b was fixed to the rotating shaft 3 by connecting the lower end of the rotating shaft 3, and the hole-shaped connection part 9, this invention is not limited to this example. . For example, the rotating body 7 b may be fixed to the rotating shaft 3 by being connected between the lower end and the upper end of the rotating shaft 3. At this time, the rotating body 7b may have a hole-shaped connecting portion 9, and may be fixed to the rotating shaft 3 with the lower end side of the rotating shaft 3 protruding from the lower surface of the rotating body 7b.

<Effect of embodiment>
(1) The molten metal stirring method according to one aspect of the present invention is arranged to extend in the height direction of the container 16 containing the molten metal, and is provided to be rotatable about its own axis in the height direction. The rotating shaft 3 is connected to the rotating shaft 3 concentrically between the rotating shaft 3 and the lower end or the lower end and the upper end in the extending direction of the rotating shaft 3, and is rotated by the rotation of the rotating shaft 3. And a rotating body 7b having discharge ports 13a to 13h provided outside the suction port 12 with respect to the axis around which the rotary shaft 3 rotates, and a stirring device (for example, a desulfurization device 14). The rotating body 7b is immersed in the molten metal accommodated in the container 16 and the rotating shaft 3 is rotated to rotate the rotating body 7b to stir the molten metal.

  According to the above configuration, in addition to the force that is physically pushed out by the main body of the rotating body 7b or the force that the molten metal is stirred by the resistance of the surface of the rotating body 7b, the centrifugal force is applied to the molten metal that has entered the inside of the rotating body 7b. Work. As a result, the effect of improving the entrainment property of the auxiliary material floating in the molten metal into the molten metal and the improvement of the stirring strength in the vicinity of the bath surface or in the entire bath can be obtained. For example, when the impeller-shaped stirring unit 7 is used. Compared with this, the stirring ability can be increased.

Further, as described above, in the method described in Patent Document 1, since a special shape of the reaction vessel is used, it is difficult to increase the stirring ability over a long period of time. Furthermore, in the case of the method described in Patent Document 1, it is conceivable to increase the difference in height of the bottom of the reaction vessel in order to solve this problem. The problem is that the capacity is reduced. On the other hand, since it is not necessary to specially process the container 16 itself, the stirring ability can be stably increased over a long period of time. Furthermore, the stirring ability can be increased without reducing the accommodation capacity of the container 16.
Furthermore, according to the said structure, even if it does not decenter the insertion position of the rotary body 7b which is the stirring part 7, stirring ability can be improved. For this reason, compared with the method described in Patent Document 2, it is not necessary to install the container 16 with high accuracy, and the stirring ability can be stably increased.

(2) In the configuration of (1), the suction port 12 is provided on the upper surface or the lower surface of the rotating body 7b facing in the height direction, and the discharge ports 13a to 13b are provided on the side surface between the upper surface and the lower surface of the rotating body. Use the stirrer provided.
According to the said structure, the improvement effect of stirring ability can be acquired with a simple structure. Further, in the configuration in which the suction port 12 is provided on the upper surface of the rotator 7b, a flow toward the suction port 12 occurs with respect to the molten metal near the bath surface and the auxiliary material floating on the bath surface. Promotion can be aimed at.
(3) In the above configuration (1) or (2), the stirring device is used under the condition of the formula (3).
According to the above configuration, the vortex recess depth H of the molten metal bath surface can be made larger than the immersion depth h of the rotating body 7b, so that the stirring ability can be further increased.

(4) The molten metal stirring device (for example, the desulfurization device 14) according to one aspect of the present invention is arranged extending in the height direction of the container 16 containing the molten metal, and has its own axis in the height direction. The rotary shaft 3 is provided so as to be rotatable around the rotary shaft 3 and is connected concentrically with the rotary shaft 3 between the lower end or the lower end and the upper end in the direction in which the rotary shaft 3 extends. And a rotary body 7b that communicates with the inside of the inlet 12 and the inside of the inlet 12 and has discharge ports 13a to 13h provided outside the inlet 12 with respect to the axis around which the rotary shaft 3 rotates.
According to the said structure, the effect similar to the structure of said (1) can be acquired.

  (5) The molten metal desulfurization method according to one aspect of the present invention is arranged to extend in the height direction of the container 16 containing the molten metal, and is provided to be rotatable around its own axis in the height direction. The rotating shaft 3 is connected to the rotating shaft 3 concentrically between the rotating shaft 3 and the lower end or the lower end and the upper end in the extending direction of the rotating shaft 3, and is rotated by the rotation of the rotating shaft 3. And a rotating body 7b having discharge ports 13a to 13h provided outside the suction port 12 with respect to the axis around which the rotary shaft 3 rotates, and a stirring device (for example, a desulfurization device 14). The rotating body 7b is immersed in the molten metal accommodated in the container 16 and the rotating body 3 is rotated by rotating the rotating shaft 3 to stir the molten metal, and the molten metal is stirred using the stirring device. The CaO-based desulfurization agent 19 is put into the molten metal.

  According to the said structure, the effect similar to the structure of said (1) can be acquired. Further, this effect makes it possible to improve the entrainment property of the CaO-based desulfurization agent 19 as an auxiliary material into the molten metal, so that the desulfurization reaction efficiency can be stably increased. Furthermore, since the desulfurization reaction efficiency can be stably increased, the time required for the desulfurization treatment can be shortened, so that the productivity in the steelmaking process can be improved.

(6) In the configuration of the above (5), the stirring device is used under the condition of the formula (3).
According to the above configuration, the vortex recess depth H of the molten metal bath surface can be made larger than the immersion depth h of the rotating body 7b, so that the stirring ability can be further increased.
(7) The molten metal desulfurization apparatus 14 according to one aspect of the present invention is arranged to extend in the height direction of the container 16 containing the molten metal, and is rotatable about its own axis in the height direction. A rotation shaft 3 provided, and a lower end in a direction in which the rotation shaft 3 extends is concentrically connected to the rotation shaft 3, and is rotated by the rotation of the rotation shaft 3, and communicates with the suction port 12 and the suction port 12. A rotating body 7b having discharge ports 13a to 13h provided on the surface outside the suction port 12 with respect to the shaft on which the rotating shaft 3 rotates, and a CaO-based desulfurizing agent 19 are introduced into the molten metal accommodated in the container 16 Charging means (for example, charging chute 18).
According to the said structure, the effect similar to said (5) can be acquired.

  Next, examples performed by the present inventors will be described. In the examples, the hot metal 15 was desulfurized using the desulfurization apparatus 14 according to the embodiment shown in FIG. Table 1 shows the conditions of the hot metal 15 and the CaO-based desulfurization agent. Further, in the example, as the rotator 7b having the suction port 12 at the upper end, two types of rotators A and Rotators B shown in Table 2 having different diameters and different sizes and numbers of discharge ports were used. Here, as a comparative example, a hot metal desulfurization treatment using an impeller similar to that used in a conventional mechanical stirring hot metal desulfurization process was also performed. The impeller dimensions are shown in Table 2. Further, in the examples and comparative examples, the desulfurization treatment is performed under a plurality of conditions in which the type and the rotation speed of the stirring unit 7 are changed from 40 rpm to 140 rpm, and the reduction rate of the sulfur concentration in the hot metal 15 before and after the treatment is determined as the desulfurization rate. As measured. Further, in the desulfurization treatment, as in the above-described embodiment, the CaO-based desulfurizing agent 19 was added from the charging chute 18 to the molten iron 15 being stirred.

In Table 3, the kind of the rotary body 7b in each condition of an Example, immersion depth h, rotation speed, X value, torque ratio, and a desulfurization rate are shown. Here, the X value is a value calculated by a ² · d · n _P · N−0.62 × H / D, and the torque ratio is normalized by setting the torque value in Comparative Example 4 to 1.00. Time value (value obtained by dividing the measured torque value by the torque value of Comparative Example 4). Moreover, it is known that the value of the dent depth H by the impeller as in the comparative example is calculated by the following equation (4) (Nagata, “Selection of Stirrer”, separate chemical industry, chemical industry, 1970 Year, Vol. 14, No. 7, p. 64). The formula (4) is calculated using the following formulas (5) to (6). In equations (4) to (6), n _B is the number of blades (sheets), b is the impeller height (m), Re is the Reynolds number, ρ is the hot metal density (assuming 7000 kg / m ³ ), and μ is The hot metal viscosity (assumed to be 0.0065 Pa · s) is shown.

FIG. 10 shows the relationship between the torque ratio and the desulfurization rate in Examples and Comparative Examples. As shown in FIG. 10, it was confirmed that the desulfurization rate of the rotating body 7b was higher with the same torque than the impeller 7a having the same height. As described above, this is considered to be because the uniform mixing time is shortened because the stirring force is strengthened in the rotating body 7b. FIG. 11 shows the relationship between the X value indicated by a ² · d · n _P · N−0.62 × H / D and the desulfurization rate. As shown in FIG. 11, a high desulfurization rate was confirmed under the condition where the X value is 0 or more, that is, the condition satisfying the expression (3) is satisfied. This is considered to be because satisfying the expression (3), the vortex dent becomes larger than the immersion depth of the rotating body 7b as described above, and the amount of desulfurization agent on the bath surface is increased.

DESCRIPTION OF SYMBOLS 1 Stirring device 2 Cylindrical container 3 Rotating shaft 4 Motor for rotation 5 Rotation speed control panel 6 Torque meter 7 Stirring unit 7a Impeller 7b Rotating body 8 Water 9 Connection unit 10 Blade 11 Connection unit 12 Suction port 13a to 13h Discharge port 14 Desulfurization device 15 Hot metal 16 Container 17 Cart 18 Input chute 19 CaO-based desulfurization agent

Claims (7)

A rotating shaft that extends in the height direction of the container containing the molten metal and is provided so as to be rotatable about its own axis in the height direction;
The rotating shaft extends concentrically with the rotating shaft between the lower end or the lower end and the upper end in the extending direction, and rotates by rotation of the rotating shaft, and communicates with the suction port and the suction port. Using a stirrer comprising: a rotating body having a discharge port provided on an outer surface of the suction port with respect to an axis on which a rotation shaft rotates;
A method for stirring molten metal, comprising: immersing the rotating body in a molten metal accommodated in the container; and rotating the rotating body to rotate the rotating body to stir the molten metal.   The agitation device is provided in which the suction port is provided on an upper surface or a lower surface of the rotating body facing the height direction, and the discharge port is provided on a side surface between the upper surface and the lower surface of the rotating body. The method for stirring molten metal according to claim 1. 3. The molten metal stirring method according to claim 1, wherein the stirring device is used under the condition of the formula (3).

a: Diameter of discharge port (m)
d: Diameter of rotating body in the direction perpendicular to the axis of rotation (m)
n _p : Number of discharge ports (pieces)
N: Number of rotations of the rotating shaft (rpm)
h: immersion depth of rotating body (m)
D: Diameter of container (m) A rotating shaft that extends in the height direction of the container containing the molten metal and is provided so as to be rotatable about its own axis in the height direction;
The rotating shaft extends concentrically with the rotating shaft between the lower end or the lower end and the upper end in the extending direction, and rotates by rotation of the rotating shaft, and communicates with the suction port and the suction port. A molten metal stirring device comprising: a rotating body having a discharge port provided on an outer surface of the suction port with respect to an axis on which a rotation shaft rotates. A rotating shaft that extends in the height direction of the container containing the molten metal and is provided so as to be rotatable about its own axis in the height direction;
The rotating shaft extends concentrically with the rotating shaft between the lower end or the lower end and the upper end in the extending direction, and rotates by rotation of the rotating shaft, and communicates with the suction port and the suction port. Using a stirrer comprising a rotating body having a discharge port provided on an outer surface of the suction port with respect to an axis around which the rotation shaft rotates,
The rotating body is immersed in the molten metal accommodated in the container, the rotating body is rotated by rotating the rotating shaft, and the molten metal is stirred.
A molten metal desulfurization method, wherein a CaO-based desulfurization agent is added to the molten metal during the stirring of the molten metal using the stirring device. 6. The molten metal desulfurization method according to claim 5, wherein the stirring device is used under the condition of the expression (3).

a: Diameter of discharge port (m)
d: Diameter of rotating body in the direction perpendicular to the axis of rotation (m)
n _p : Number of discharge ports (pieces)
N: Number of rotations of the rotating shaft (rpm)
h: immersion depth of rotating body (m)
D: Diameter of container (m) A rotating shaft that extends in the height direction of the container containing the molten metal and is provided so as to be rotatable about its own axis in the height direction;
The rotating shaft extends concentrically with the rotating shaft between the lower end or the lower end and the upper end in the extending direction, and rotates by rotation of the rotating shaft, and communicates with the suction port and the suction port. A rotating body having on its surface a discharge port provided outside the suction port with respect to an axis on which the rotation shaft rotates;
An apparatus for desulfurizing molten metal, comprising: charging means for charging a CaO-based desulfurizing agent into the molten metal accommodated in the container.

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