JP2016216781A - Desulfurization method of molten pig iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desulfurization method of molten pig iron capable of managing an inclusion state of a desulfurizing agent into a molten pig iron bath surface and improving desulfurization efficiency.SOLUTION: An impeller 7 is immersed in molten pig iron 3 in a treatment vessel 4, the impeller is rotated for forming a swirl on a bath surface of molten pig iron and stirring, and when a discharged desulfurizing agent is included and diffused in the molten pig iron, an inclusion state of the desulfurizing agent is detected at least when, the impeller 7 is rotated and the swirl is formed on the bath surface of the molten pig iron, then immersion depth of the impeller is adjusted according to the detected inclusion state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for desulfurizing hot metal in which a flux is introduced into hot metal and the impeller is rotated to mechanically stir the hot metal so that the sulfur component in the hot metal is hatched by a desulfurization reaction and removed as slag. About.

As a conventional hot metal desulfurization method, a desulfurizing agent is added to the hot metal in the hot metal ladle, and the central part of the hot metal bath surface is set to 150 to 300 r using an impeller having a representative total of 1/10 to 1/3 of the inner diameter of the hot metal ladle. . p. m. A hot metal desulfurization method has been proposed in which the hot metal is rotated and stirred at a high speed to desulfurize the hot metal by entraining a desulfurizing agent in the swirl sinking portion formed at the center of the hot metal bath surface (see, for example, Patent Document 1). .
As another hot metal desulfurization method, a degreasing agent is added to a hot metal bath held in a molten metal refining vessel, an impeller is immersed and rotated, the hot metal bath is stirred, the outer diameter of the impeller and the hot metal bath are stirred. There has been proposed a hot metal desulfurization method in which the ratio of the metal smelting vessel to the inner diameter of 1/10 to 2/3 is rotated while the impeller is moved up and down in the hot metal bath (for example, Patent Documents). 2).

Japanese Patent Publication No.42-12343 JP 2001-49319 A

However, in the conventional example described in Patent Document 1, the desulfurization agent floating on the hot metal surface is entrained in the vortex by rotating the impeller immersed in the center of the hot metal bath surface in the hot metal ladle. However, because the impeller immersion depth is not taken into account, there is a case where the desulfurization agent is not sufficiently entrained in the surface of the desulfurization agent hot metal bath due to an error in the shape of the impeller and the immersion depth. There is a problem that the residual sulfur (S) concentration after the desulfurization treatment becomes unstable.
Further, in the conventional example described in the above-mentioned Patent Document 2, by rotating the impeller while moving up and down, the molten iron is sequentially stirred at different depth positions depending on time, and the molten iron can be evenly stirred uniformly. However, since the impeller is moved up and down at all times, there is a problem that the load of the lifting equipment for raising and lowering the impeller is large and the risk of equipment failure increases.
Therefore, an object of the present invention is to provide a hot metal desulfurization method capable of improving the desulfurization efficiency by managing the state of the desulfurization agent entrained in the hot metal bath surface.

  In order to achieve the above object, the hot metal desulfurization method according to one aspect of the present invention involves immersing an impeller in hot metal in a processing vessel, rotating the impeller to form a vortex on the hot metal bath surface, and stirring. When the introduced desulfurizing agent is entrained and diffused in the hot metal, the impeller is rotated at least to detect the entrainment state of the desulfurizing agent when a vortex is formed on the bath surface of the hot metal, and according to the detected entrainment state Adjust the immersion depth of the impeller.

  According to one aspect of the present invention, the desulfurization agent is adjusted by adjusting the immersion depth of the impeller when the vortex formed after the start of desulfurization is stabilized at least when the desulfurization agent is entrained on the hot metal bath surface formed by the impeller. It is possible to accurately control the entrainment state of the impeller, and to reduce the load on the lifting equipment of the impeller while improving the desulfurization efficiency.

It is a schematic diagram which shows the hot metal desulfurization equipment applicable to 1 aspect of this invention. It is a flowchart which shows an example of the stirring control processing procedure performed with the stirring control apparatus of FIG. It is a graph which shows the relationship between a lime input amount and a desulfurization rate.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

Further, the embodiment described below exemplifies an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, The layout is not specified as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.
In one form of the hot metal desulfurization equipment 1 to which the present invention can be applied, as shown in FIG. 1, a hot metal ladle 4 in which a hot metal 3 is charged is positioned and arranged in a housing 2. In the housing 2, an elevating body 5 is disposed above the hot metal ladle 4 and is guided by a guide rail (not shown) so as to be movable up and down. The elevating body 5 is formed in a box shape with an upper plate portion 5a and a lower plate portion 5b, a left plate portion 5c and a right plate portion 5d, and is guided to the left plate portion 5c and the right plate portion 5d by a guide rail. Wheels 5e are arranged.

A rotation drive motor 6 is disposed at the center position on the upper surface side of the lower plate portion 5 b of the elevating body 5, and the rotation shaft 7 a of the impeller 7 is connected to the rotation shaft of the rotation drive motor 6. When the impeller 7 is immersed in the bath surface of the hot metal 3 filled in the hot metal ladle 4, the impeller 7 is rotationally driven in one direction or in the forward and reverse directions by the rotary drive motor 6. A vortex heading toward is formed.
The elevating body 5 is moved up and down by a hoisting drive device 8 formed of, for example, a winch disposed on the upper surface of the housing 2.
Further, above the open end of the hot metal ladle 4, a color imaging camera 10 that performs color imaging of a vortex formed at the center of the bath surface in the hot metal ladle 4 is arranged. The eddy current image captured by the color imaging camera 10 is sent to the image processing device 11. At this time, the eddy current image is an image obtained by imaging a state in which a desulfurizing agent or soot that does not self-emit light floating on the bath surface of the molten iron 3 is caught in the molten iron 3 that is a self-luminous body accompanying the rotation of the impeller 7. . For this reason, the eddy current image is processed by the image processing device 11 to extract the eddy current that is the movement trajectory of the desulfurization agent and the soot from the luminance difference due to the temperature difference between the hot metal 3 and the desulfurization agent and the soot, and the extracted eddy current image data Is generated.

On the other hand, the image captured by the imaging camera 10 is also sent to the image display device 12, and the image display device 12 displays the eddy current state of the hot metal.
The eddy current image data output from the image processing device 11 is sent to the stirring control device 13. This agitation control device 13 drives the winding drive device 8 to control the immersion depth of the impeller 7 and the rotation that drives the rotation drive motor 6 to control the rotation speed of the impeller 7. A drive command is output to the control device 15.
Here, in the immersion depth control device 14, the winding drive device 8 is driven forward / reversely, and the rotation number detection signal of the rotation number detector 8 a connected to the rotation shaft of the winding drive device 8 is input. From the upper end of the impeller 7 from the rotation speed detection value obtained based on the detection signal, the diameter of the winding drum of the hoisting driving device 8, the protruding length of the impeller 7 from the elevator 5 and the height position of the open end surface of the hot metal ladle 4. The immersion depth h up to the open end face of the hot metal ladle 4 is detected, and the calculated immersion depth h is output to the stirring control device 13.

Similarly, in the rotation control device 15, the rotational drive motor 6 is rotationally driven in one direction, for example, and the rotational speed detection signal of the rotational speed detector 6a connected to the rotational shaft of the rotational drive motor 6 is input. Control is performed so that the rotation speed detection value obtained based on the rotation speed detection signal matches the target rotation speed, and the rotation speed detection value is output to the stirring control device 13.
The stirring control device 13 includes an arithmetic processing device such as a microcomputer, and the lifting / lowering body 5 is retracted so that the lower end of the impeller 7 is spaced upward from the open end of the hot metal ladle 4 as shown in FIG. In a state where the stirring start switch 13a is turned on after the hot metal ladle 4 filled with the hot metal 3 is set at a predetermined position in the housing 2, the stirring process shown in FIG. 2 is executed.

The agitation process, first, outputs an initial immersion depth command to lower the impeller 7 to the initial immersion depth h ₀ with respect to the immersion depth control device 14 in Step S1 (Step S1). The initial immersion depth h ₀ specified by this initial immersion depth command ensures that the impeller 7 is in the stationary bath surface of the hot metal 3 regardless of the filling amount of the hot metal 3 in the hot metal pan 4 (for example, 200 t to 320 t). The immersion depth is set.
Next, the process proceeds to step S2, and the immersion depth h from the open end of the hot metal pan 4 of the impeller 7 to the upper end of the impeller 7 detected by the immersion depth control device 14 is read, and this immersion depth h is the initial immersion depth. it is determined whether because reaches the h _0, when it does not reach the initial immersion depth h ₀ waits until the impeller 7 reaches the initial immersion depth h _0, the impeller 7 in the initial immersion depth h ₀ When it reaches, the process proceeds to step S3.

In step S3, a rotation command for rotating the impeller 7 at the target rotation speed is output to the rotation control device 15, and then the process proceeds to step S4. Here, the target rotation speed is set to a rotation speed at which the impeller 7 generates a vortex that draws the hot metal 3 into the center of the hot metal ladle 4 at a rotation speed of, for example, 80 times / minute or more in one direction.
In step S4, it is determined whether or not the rotational speed of the impeller 7 has reached the target rotational speed. If the rotational speed of the impeller 7 has not reached the target rotational speed, the process waits until the target rotational speed is reached, and reaches the target rotational speed. When it reaches, the process proceeds to step S5.
In step S5, a desulfurizing agent charging instruction is output to the desulfurizing agent charging device 9, and then the process proceeds to step S6.
In this step S6, it is determined whether or not a predetermined time has elapsed until the desulfurizing agent introduced into the hot metal bath surface starts to be entrained in the vortex formed by the impeller 7, and when the predetermined time has not elapsed. The process waits until a predetermined time elapses. When the predetermined time elapses, the process proceeds to step S7.

In this step S7, eddy image data which is a movement locus of the desulfurization agent or the like by the eddy current is read from the image processing apparatus 11, and then the process proceeds to step S8 to determine whether or not the eddy current is formed based on the read eddy image data. If the vortex is formed, the process proceeds to step S9, where the vortex is not formed and the movement locus of the desulfurizing agent or the like is a ring shape along the inner periphery of the hot metal ladle 4, It is determined that the immersion depth h of the impeller 7 is too deep, and the process proceeds to step S10.
In step S9, it is determined whether or not a proper vortex is formed so that the inner end of the vortex represented by the vortex image data is within the appropriate range A inside the region surrounded by the outer peripheral edge at the upper end of the impeller 7 shown in FIG. If the proper vortex is formed, the stirring process is terminated as it is. On the other hand, when the determination result of step S9 is not within the appropriate range A surrounded by the outer peripheral edge of the upper end of the impeller 7, the process proceeds to step S10.

In step S10, an impeller raising command for gently raising the impeller 7 is output to the immersion depth control device 14, and then the process proceeds to step S11 to read the vortex image data again from the image processing device 11 and then step S12. Migrate to
In this step S12, it is determined whether or not the immersion depth h of the impeller 7 has reached the upper limit immersion depth hu. Here, the upper limit immersion depth hu is, for example, a depth at which the outer peripheral edge at the upper end of the impeller 7 is exposed from the hot metal bath surface, and the upper peripheral edge at the upper end of the impeller 7 in the image processing device 11 based on the image information of the color imaging camera 10. Or the upper limit immersion depth hu may be calculated by calculation from the height of the hot bath surface of the hot metal, the rotational speed of the impeller 7 and the inner diameter of the hot metal ladle 4.

When the determination result of step S12 indicates that the immersion depth h of the impeller 7 has not reached the upper limit immersion depth hu, the process proceeds to step S13, and the inner end of the vortex is determined from the vortex image data read in step S11. It is determined whether or not it is within the proper range A surrounded by the outer peripheral edge of the upper end, and when the inner end of the vortex is within the proper range A, it is determined that the desulfurization agent is in an appropriate state. After moving to S14 and outputting an impeller rise stop command to the immersion depth control device 14, the stirring process is terminated.
If the determination result in step S13 shows that the inner end of the vortex does not fall within the appropriate range A, the process returns to step S11.

On the other hand, when the determination result in step S12 indicates that the impeller immersion depth h reaches the upper limit immersion depth hu, the process proceeds to step S15, and the impeller 7 is gently lowered with respect to the immersion depth control device 14. After outputting the impeller lowering command, the process proceeds to step S16.
In step S16, the vortex image data is read again from the image processing apparatus 11, and then the process proceeds to step S17 to determine whether the impeller immersion depth h has reached the lower limit immersion depth hd. In this determination, the lower end of the impeller 7 is set to a value having a predetermined depth so that the lower end of the impeller 7 does not contact the inner bottom surface of the hot metal ladle 4.

When the determination result of step S17 indicates that the immersion depth h of the impeller 7 has not reached the lower limit immersion depth hd, the process proceeds to step S18, and the inner end of the vortex is surrounded by the outer periphery of the upper end of the impeller 7. It is determined whether or not it is within the range A, and when the inner end of the vortex is within the appropriate range A, it is determined that the state of the desulfurization agent is appropriate and the immersion depth control device 14 is determined. After the impeller descent stop command is output, the stirring process is terminated.
If the determination result in step S18 indicates that the inner point of the vortex is not within the appropriate range A, the process returns to step S16.
On the other hand, when the determination result of step S17 shows that the immersion depth h of the impeller 7 reaches the lower limit immersion depth hd, the process returns to step S10.

Next, a method for desulfurizing the hot metal 3 in the hot metal ladle 4 using the color imaging camera 10, the image processing device 11, the stirring control device 13, the immersion depth control device 14 and the rotation control device 15 will be described.
First, it is assumed that the lifting body 5 is in a retracted position where the lower end of the impeller 7 is spaced above the open end of the hot metal ladle 4 as shown by the chain line in FIG.
In this state, the hot metal ladle 4 filled with the hot metal 3 is positioned and disposed in the housing 2 on the lower end side of the impeller 7 so that the central axis thereof coincides with the central axis of the impeller 7.
When the positioning of the hot metal ladle 4 is completed, turning on the stirring start switch 13a of the stirring control device 13 causes the stirring control device to start the stirring process shown in FIG.

For this reason, in the state where the rotation of the impeller 7 is stopped, the initial immersion position where the immersion depth h of the impeller 7 is surely immersed in the bath surface of the molten iron 3 regardless of the filling amount of the molten iron 3 (for example, 200 t to 320 t). It is immersed until h ₀ (steps S1, S2).
When the impeller 7 reaches the initial immersion position h ₀ , an initial immersion completion notification is output from the immersion depth control device 14 to the stirring control device 13, and the stirring control device 13 issues a rotation command to the rotation control device 15. Output (step S3). Thereby, the rotation drive motor 6 starts to rotate so that the impeller 7 rotates, for example, in one direction at a rotation speed target value of, for example, 80 times / minute or more.

When the impeller 7 is rotated, the bath surface of the hot metal 3 starts to rotate, and a vortex corresponding to the immersion depth h of the impeller 7 is formed on the bath surface of the hot metal 3 as the impeller 7 rotates. When the rotational speed of the impeller 7 reaches the rotational speed target value, the desulfurizing agent is charged from the desulfurizing agent charging device 9 to the outer peripheral side on the bath surface of the hot metal 3 (step S5). As this desulfurizing agent, a CaO—CaF ₂ type flux for performing desulfurization treatment, and a deoxidizing material (Al) and slag (oxide) that further promotes the desulfurization reaction are used, and the following desulfurization is performed depending on the flux. Desulfurization is performed by carrying out the reaction.
S + CaO = CaS + O
Here, CaF ₂ contained in the flux is added to hatch CaS.
Thereafter, after the time required for the vortex of the hot metal bath surface formed by the impeller 7 to stabilize from the start of rotation of the impeller 7 has elapsed (for example, 2-3 minutes from the start of rotation), the stirring control device 13 adjusts the immersion depth. Execute the process. In this immersion depth adjustment processing, eddy current image data input from the image processing device 11 is read, and whether the inner tip of the vortex is within the appropriate range A within the upper end outer diameter of the impeller 7 from the eddy current image data. Determine whether or not.

At this time, when the vortex is not spiral and is along the inner peripheral surface of the hot metal ladle 4 or when the inner end of the vortex is separated from the outer diameter of the impeller 7 even if the vortex is formed, the impeller 7 is immersed. Determining that the depth h is not appropriate (steps S8, S9), and determining that the immersion depth h of the impeller 7 is appropriate when the inner tip of the vortex has reached the inside of the outer diameter of the impeller 7.
In this determination process, when the inner tip of the vortex flow is within the appropriate range A, it is determined that the immersion depth h of the impeller 7 is appropriate, and the immersion depth adjustment process is terminated. When it is determined that the depth h is not appropriate, the immersion depth adjustment process is continued, an ascending command is output to the immersion depth control device 14 (step S10), and the lifting body 5 is compared by the winding drive device 8. Increase at a slow rate.

Vortex image data sequentially input from the image processing device 11 in the ascending process of the impeller 7 is analyzed, and a vortex flow is formed until the immersion depth h of the impeller 7 reaches the immersion depth upper limit hu. It is determined whether or not the inner tip is within the correction range within the upper end outer diameter range of the impeller 7 (steps S11 to S13).
If the inner tip of the vortex flows within the appropriate range A within the upper end outer diameter range of the impeller 7 before the immersion depth h of the impeller 7 reaches the immersion depth upper limit hu, an appropriate vortex flow is formed. It is determined that the desulfurization agent is in an appropriate state, and an impeller elevation stop command is output to the immersion depth control device 14 (step S14), the immersion depth adjustment process is terminated, and the elevation of the impeller 7 is stopped.

However, when the impeller 7 reaches the upper limit hu of the immersion depth before the inner tip of the vortex flows within the appropriate range A within the outer diameter range of the upper end of the impeller 7 during the ascending process of the impeller 7. Then, it is determined that the immersion depth h of the impeller 7 is too shallow, and a lowering command to gently lower the impeller 7 is output to the immersion depth control device 14 (step S15), and the impeller 7 is gently lowered.
In the descent process of the impeller 7 as well, the eddy current image data is sequentially read from the image processing device 11 (step S16), and the immersion depth h of the impeller 7 reaches the immersion depth lower limit hd. If the inner tip of the vortex flow is within the appropriate range A within the upper end outer diameter range of the impeller 7 before starting, a descent stop command is output to the immersion depth controller 14 (step S19), and the immersion depth is adjusted. The process ends.
However, when the immersion depth h of the impeller 7 reaches the immersion depth lower limit hd before the inner tip of the vortex is within the appropriate range A, the impeller 7 is gently raised again to the immersion depth control device 14. An ascent command is output (step S10), the impeller 7 is gently raised, and the immersion depth h of the impeller 7 in which the inner tip of the vortex is within the appropriate range A is searched again.

In addition, the agitation control device 13 outputs a rotation stop command to the rotation control device 15 when a predetermined agitation time (for example, 22 to 23 minutes) has elapsed from the start of agitation, and thereby the rotation control device 15 performs rotation driving. The rotation drive of the motor 6 is stopped, and then the retracting command to the retracting position where the lower end of the impeller 7 is above the open end of the hot metal ladle 4 is outputted to the immersion depth control device 14. Thereby, the hoisting driving device 8 is driven by the immersion depth control device 14 to raise the elevating body 5 to the retracted position.
Thereafter, the generated desulfurized slag rises in the hot metal ladle 4 to cover the hot metal surface, and the desulfurization process of the hot metal 3 is finished in a stationary state.
In this state, the hot metal ladle 4 is moved from the housing 2 to the outside, and a new hot metal ladle 4 is positioned and set at the center position of the housing 2, and the desulfurization process is started again.
The immersion depth adjustment process is not limited to being performed only once at the start of desulfurization, and may be performed a plurality of times at predetermined time intervals.

Thus, according to the desulfurization method of the present embodiment, the impeller 7 is rotated while the impeller 7 is immersed in the bath surface of the hot metal 3 to the initial immersion depth h ₀ so as to start desulfurization of the hot metal. When a stable vortex flow is formed, a desulfurizing agent is introduced into the upper surface of the hot metal 3 along the inner peripheral surface of the hot metal pan 4, and the desulfurizing agent is bathed as the impeller 7 rotates. The eddy current image data obtained by imaging the state of the eddy current formed in the center of the surface with the color imaging camera 10 is supplied to the image processing device 11 to extract the eddy current image data which is the movement locus of the desulfurizing agent, etc. Based on the eddy current image data, the immersion depth h of the impeller 7 is adjusted so that the movement trajectory of the desulfurizing agent is within an appropriate range A within the upper end outer diameter range of the impeller 7.

For this reason, it is possible to adjust the immersion depth of the impeller 7 to an appropriate state immediately after the start of the desulfurization, and thereafter, the immersion depth adjustment process is not performed or is performed intermittently, so that the impeller 7 is moved up and down. The effect that the load with respect to the winding drive device 8 can be reduced is obtained.
Moreover, the initial immersion depth h _{0 in} which the impeller 7 is immersed is set to a depth that ensures the immersion in the stationary bath surface of the hot metal 3 regardless of the filling amount of the hot metal 3 in the hot metal pan 4 (for example, 200 t to 320 t). By doing this, when the impeller 7 is rotated, it is possible to reliably prevent the upper portion of the impeller 7 from protruding upward from the bath surface of the molten iron 3 and scatter the molten iron 3, thereby stably forming the eddy current. be able to.

Further, the vortex formed on the hot metal bath surface is detected, the state of the desulfurization agent is judged, and the immersion depth h of the impeller 7 is adjusted so that the state of entrainment becomes good. Dispersion in the hot metal 3 can be performed reliably. As a result, according to this embodiment, as shown in FIG. 3, the desulfurization rate is 70% when the impregnation depth h of the impeller 7 is not adjusted in the vicinity of 3 [kg / t], which is the normal lime input amount. Compared with before and after, the desulfurization rate can be improved to 80% or more. Furthermore, even if the lime input amount 1 [kg / t] is smaller than the normal lime input amount, the desulfurization rate around 60% when the immersion depth h of the impeller 7 is not adjusted can be improved to 75% to 82%.
Here, the desulfurization rate is a value indicating the difference between the sulfur concentration in the hot metal before the desulfurization treatment and the sulfur concentration in the hot metal after the desulfurization treatment as a percentage with respect to the sulfur concentration in the hot metal before the desulfurization treatment. It is represented by 1.

  In the above embodiment, the vortex image data captured by the color imaging camera 10 is supplied to the image processing device 11 to extract the vortex image data that is the movement locus of the desulfurization agent, and the impeller 7 is based on the vortex image data. However, the present invention is not limited to this, and the image data captured by the color imaging camera 10 is supplied to the image processing apparatus 11, and the image processing apparatus 11 is self-adjusted. Quantize the image data of the hot metal 3 that is the illuminant, calculate the speed vector representing the impeller stirring speed based on the moving distance, moving direction and required time of pixels of the same density, and match this stirring speed with the target stirring speed As such, the immersion depth h of the impeller 7 may be adjusted.

In the above-described embodiment, the case where the color imaging camera 10 is applied as the imaging device for the hot metal bath surface has been described. However, a monochrome imaging camera can also be applied, and eddy currents due to temperature differences using infrared thermography. Image data may be detected.
Furthermore, in the above-described embodiment, the case of determining the entrainment state of the desulfurizing agent based on the eddy current image data has been described. However, the present invention is not limited to this. The vortex image is quantized and image-processed to calculate the stirring flow rate of the molten iron, and the immersion depth h of the impeller 7 is adjusted so that the calculated stirring flow rate matches the preset target stirring flow rate. Good.

In the above embodiment, the case where the state of the desulfurization agent is determined based on the image data obtained by imaging the eddy current has been described. However, the present invention is not limited to this, and the hot metal eddy current formed by the rotation of the impeller 7 is described. The depth of the recess is measured with a non-contact distance meter such as a microwave rangefinder, the depth of the recess is below the immersion depth h of the impeller 7, and the outer periphery of the upper end of the impeller 7 is exposed from the bath surface of the hot metal 3. You may make it adjust the immersion depth h of the impeller 7 so that it may not.
In the above embodiment, the impeller 7 on startup irrespective of the loading of hot metal 3 into hot metal pan 4 (e.g. 200T～320t), to the initial dip position h ₀ to reliably immersed in the bath surface in the hot metal 3 has been described for submerged, is not limited thereto, and sets the initial immersion position h ₀ in shallow, it may be adjusted immersion depth h while lowering the impeller 7.

  DESCRIPTION OF SYMBOLS 1 ... Hot metal desulfurization apparatus, 2 ... Housing | casing, 3 ... Hot metal, 4 ... Hot metal ladle, 5 ... Lifting body, 6 ... Rotation drive motor, 7 ... Impeller, 8 ... Winding drive device, 9 ... Desulfurization agent injection apparatus, 10 ... Color imaging camera, 11 ... image processing device, 12 ... image display device, 13 ... stirring control device, 14 ... immersion depth control device, 15 ... rotation control device

Claims (6)

  The impeller is immersed in the hot metal in the processing vessel, and the impeller is rotated to form a vortex on the bath surface of the hot metal and stirred, and when the introduced desulfurizing agent is entrained and diffused into the hot metal, at least the impeller is A hot metal desulfurization method characterized by detecting a state of entrainment of the desulfurizing agent when a vortex is formed on a hot metal bath surface by rotation and adjusting an immersion depth of the impeller according to the detected entrainment state .   The detection of the entrainment state is performed by imaging the vortex formed on the bath surface with an imaging device, extracting the eddy current image data by performing image processing on the captured vortex image, and extracting the impeller immersion depth. 2. The hot metal desulfurization method according to claim 1, wherein the hot metal desulfurization method is performed by adjusting the vortex inner tip of the eddy current image data so as to be within the outer diameter of the impeller.   The detection of the entrainment state is performed by imaging the vortex formed on the bath surface with an imaging device, image-processing the captured vortex image to calculate the stirring flow velocity of the molten iron, and the immersion depth of the impeller is calculated 2. The hot metal desulfurization method according to claim 1, wherein the flow rate is adjusted so as to coincide with the target stirring flow rate.   4. The hot metal according to claim 2, wherein the imaging device is configured with one of a camera that picks up a luminance difference between the hot metal and the desulfurizing agent and an infrared thermography that picks up the temperature distribution of the hot metal. Desulfurization method.   The entrainment state is detected by measuring the dent depth at the center of the vortex with a non-contact distance meter. The immersion depth of the impeller is such that the measured dent depth matches the target dent depth. The hot metal desulfurization method according to claim 1, wherein the hot metal is desulfurized.   The adjustment of the immersion depth of the impeller is determined by determining the entrainment state when the impeller is rotationally driven in a state where the impeller is immersed in the initial immersion depth, and when the entrainment state is not appropriate, the immersion depth of the impeller is determined. Once it is moved from the initial immersion depth to either one of rising and lowering, and the entrainment situation is not improved, the impeller immersion position is adjusted by moving in the reverse direction beyond the initial immersion depth. 6. The hot metal desulfurization method according to claim 1, wherein the hot metal is desulfurized.

Images