JPH0499212A - Apparatus for desulfurizing molten iron - Google Patents

Abstract

PURPOSE:To obtain an impeller having powerful stirring force in low cost, to prolong the service life of the impeller and to execute desulfurization in low cost by providing rotary shaft set as freely coming in/out to a vessel for charging the molten iron arranged in two upper and lower steps at lower part of the rotary shaft. CONSTITUTION:The rotary shaft 4 is vertically set in the molten iron ladle 3 so as to be dipped at almost middle of the depth of the molten iron 1, and while rotating the impeller blades 6 arranged in two steps with the shaft 4, at the same time, a desulfurizing agent is floated on the pressurized gas and injected in the molten iron from the injection hole 9. By the powerful stirring movement formed in the molten iron, finely and dispersedly the desulfurizing agent is sufficiently divided, and the desulfurization can be advantageously accelerated by increase of the reaction chance with the molten iron and increase of reaction interface area accompanying the increase of the above chance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hot metal desulfurization apparatus. For more details,
The present invention relates to a hot metal desulfurization device that is capable of improving the desulfurization rate while preventing significant erosion of impeller blades used when desulfurizing hot metal, and that can desulfurize at low cost.

(Conventional technology) Conventionally, technology using an impeller for desulfurizing hot metal has been widely used.
It was being implemented.

For example, Japanese Patent Publication No. 42-12343 discloses that an impeller installed in hot metal contained in a hot metal tank is rotated in a fixed direction, and the hot metal is stirred by the stirring force generated on the hot metal by this rotation. For example, a technique has been disclosed in which hot metal is desulfurized by adding a desulfurizing agent such as CaO into the hot metal.

FIG. 6(a) is a schematic perspective view showing the structure of an impeller used in a hot metal desulfurization apparatus disclosed in Japanese Patent Publication No. 42-12343, and FIG. FIG. 3 is a schematic cross-sectional view showing a hot metal ladle 3 when desulfurization is performed.

That is, the impeller 5 shown in FIGS. 6(a) and 6(b) has four mutually perpendicular impeller blades 6 at its lower part, and these four impeller blades 6 rotate at # 4, and is configured so that the molten metal I can be stirred by the rotational movement of the rotating shaft 4 (rotating in the direction of the arrow in the figure). Further, on the rotating side blade surface 7 of the impeller blade 6, a vortex is generated not only in the horizontal direction of the hot metal bath but also in the upward direction of the bath, so that the hot metal 1 can be stirred also in the height direction of the hot metal bath. The blade angle θ is set so that the blade surface 7 faces downward in the lower direction of the bath, and consideration is given to making desulfurization as efficient as possible by such a device.

In addition, in order to prevent the impeller 5 itself from melting and softening and being damaged when it comes into contact with the hot metal 1, the rotating shaft 4 is
The surfaces of both the impeller blades 6 and the impeller blades 6 are covered with a refractory material. Further, 2 indicates a desulfurizing agent such as CaO, which is introduced from the desulfurizing agent inputting chute.

However, the impeller 5 in the hot metal desulfurization device proposed in Japanese Patent Publication No. 42-12343 is configured to rotate in a constant direction at a constant speed, and when the impeller 5 is rotated in hot metal, The flow of hot metal reaches a steady state in a relatively short period of time, and the ability to stir the hot metal decreases, so it is not easy to maintain a high ability to stir the hot metal for almost the entire desulfurization period. Ta.

In addition, as described above, the surface of the impeller 5 is covered with a refractory material, and as a result of its use, the surface of the impeller 5 is eroded due to contact with the hot hot metal 1, causing the impeller 5 to become uneven. There was also a problem in that as the wear progressed, the stirring force of the impeller 5 against the hot metal 1 decreased.

Therefore, in order to solve this problem, the special public
Publication No. 6605 discloses that by adding a desulfurizing agent to hot metal while rotating the impeller forward and backward for 1 to 3 minutes, desulfurization efficiency can be improved while preventing shortening of life caused by uneven wear of the impeller. The techniques used to maintain this are shown in the photo.

In addition, as another proposal, Japanese Patent Publication No. 55-30563 discloses that pressurized gas and desulfurization agent are injected into hot metal from holes opened in the opposite direction to the rotational direction of the impeller, using only the stirring force of the impeller. Although no technology has been proposed to obtain a desulfurization efficiency higher than that obtained, this
Since most of the desulfurization reaction in Publication No. 563 occurs during the rise of the desulfurization agent in the hot metal, blowing conditions are specified so that the desulfurization agent stays in the hot metal for as long as possible.

(Problems to be Solved by the Invention) However, the technology proposed in the above-mentioned Japanese Patent Publication No. 55-6605 is unique to the impeller used (size,
Because only the desulfurization efficiency (based on the shape, etc.) can be obtained, it has been almost impossible to further improve the desulfurization efficiency.

Furthermore, with the technology proposed in Japanese Patent Publication No. 55-30563, wear and tear of the gas hole opening progresses due to hot metal resistance during use, so it is almost impossible to eliminate the decrease in desulfurization rate. It was impossible.

As described above, in the conventional technology, in hot metal desulfurization equipment that performs desulfurization by rotating the impeller and stirring the hot metal, it is necessary to improve the stirring power of the hot metal, extend the life of the impeller, and reduce the cost. It has been almost impossible to perform desulfurization at low cost.

In other words, the blade surface of the impeller in conventional hot metal desulfurization equipment collides with the high-temperature hot metal and desulfurization agent particles at high speed, so erosion is inevitable. In equipment that rotates in the direction of rotation, the front face of the impeller in the direction of rotation is significantly damaged compared to the rear face in the direction of rotation, which reduces the stirring efficiency of hot metal and further shortens the life of the impeller, requiring repair. This had the disadvantage of increasing costs.

The purpose of the present invention is to solve the problems of these conventional hot metal desulfurization devices, and to provide a device that is inexpensive and has a strong stirring power.
Another object of the present invention is to extend the life of the impeller and to provide a hot metal desulfurization device that can desulfurize at low cost.

(Means for Solving the Problems) The present inventors have made extensive studies in order to solve the above problems.

As a result, the present inventors have found that, by providing impeller blades having the same vertical rotation axis and arranged in upper and lower stages in a hot metal bath placed in a container such as a ladle, it is more preferable to When operated under normal conditions using a desulfurization device that has gas holes communicating with the rotating shaft and the impeller blades on both sides of the blades and also has jet ports for pressurized gas and desulfurization agent, the desulfurization rate improves. I found out that. Furthermore, when operating the desulfurization equipment, the impeller rotation speed is increased by about 20% from the normal rotation speed, and the impeller is rotated forward and backward for 2 to 3 minutes. It has been found that a considerably better mixing and stirring state can be produced compared to the simple rotational stirring in a constant direction and jet stirring of pressurized gas and desulfurizing agent in a constant rotational direction.

Based on such knowledge, the present inventors conducted further studies and completed the present invention.

Here, the gist of the present invention is to provide a rotating shaft that is installed in a container that accommodates hot metal so as to be able to move in and out, and impeller blades that stir the hot metal that are provided below the rotating shaft in two stages, upper and lower. This is a hot metal desulfurization equipment characterized by:

Furthermore, in the hot metal desulfurization apparatus according to the present invention described above, it is possible to incorporate a rotation direction switching mechanism of the rotating shaft.
This is preferable from the viewpoint of stirring the hot metal more reliably.

Furthermore, in the hot metal desulfurization apparatus according to the present invention, it is preferable that the impeller blade has a desulfurizing agent jet port from the viewpoint of more reliably stirring the hot metal.

In the above-mentioned invention, the "rotational direction switching mechanism of the rotating shaft"
There is no need to limit the method to a specific method.

Any known means may be used.

Furthermore, the shape of the impeller blades is not particularly limited. In the present invention, any known impeller blade may be used.

In addition, in the above-mentioned present invention, a mode in which the impeller has a desulfurizing agent spout is also shown, but this also does not require any particular limitation.
It may be a spout as disclosed in the above publication.

Note that, as is well known, in order to spout the desulfurizing agent from this spout, it is sufficient to spout a carrier gas such as N2 gas from the spout to spout the desulfurizing agent. Note that the shape, installation position, number, etc. of the jet nozzle are not limited in any way.

(Function) Hereinafter, the function of the hot metal desulfurization apparatus according to the present invention will be explained.

The basic concept for desulfurizing hot metal in the hot metal desulfurization apparatus according to the present invention is the same as that of conventionally widely known hot metal desulfurization apparatuses. In other words, desulfurization of the hot metal is carried out by adding a desulfurizing agent to the hot metal while stirring the hot metal.

In addition, the desulfurization reaction in the hot metal desulfurization apparatus according to the present invention reduces S in the hot metal by combining Ca and S, which are desulfurization agents.
However, when the S concentration in the hot metal decreases, resulfurization occurs, which is a phenomenon in which the S fixed in the slag removed onto the hot metal bath returns to the hot metal. For this reason, the desulfurization reaction is always replaced with fresh unreacted hot metal (i.e. 34f of the hot metal involved in the desulfurization reaction).
In order to prevent a decrease in f, it is possible to make the process proceed stably by stirring the hot metal. In addition, if the slag with a high S concentration (desulfurization agent), which is likely to cause resulfurization, is lifted upward and prevented from coming into contact with the hot metal, resulfurization will be reduced and the desulfurization reaction will proceed stably. I can do it. For these reasons, it is more effective to blow a desulfurization agent into hot metal than to use the upper charging slag as a desulfurization agent.

Furthermore, when a desulfurizing agent is injected from near the tip of an impeller installed in hot metal, it is affected by the hot metal being stirred, and the desulfurizing agent gets caught up in the hot metal flow, increasing the chance of contact with the hot metal, and the reaction rate decreases. It is more suitable for increasing the temperature.

Next, in the hot metal desulfurization apparatus according to the present invention, by providing the impeller blades in multiple stages, preferably in two stages, below the rotating shaft, it is possible to powerfully subdivide or disperse the desulfurization agent. Desulfurization can be advantageously promoted by increasing the reaction interface area with hot metal. In other words, when stirring the impeller in conventional equipment, in addition to the flow directed from the impeller in the circumferential direction, a flow that diffuses upward or downward is also generated, and the injected desulfurization agent is dispersed based on the difference in specific gravity. Most of the force was expected to float upward, riding on the upward diffusion current. Therefore, the residence time of the desulfurizing agent in the hot metal is reduced as a result, making it difficult to improve the desulfurization rate.

On the other hand, as in the hot metal desulfurization equipment according to the present invention, by providing the impeller in two stages, upper and lower, the desulfurizing agent spouted into the hot metal from the spout of the impeller provided in the lower stage is transferred to the upper stage. Under the influence of the downward flow formed by the rotation of the impeller installed in the hot metal bath, the hot metal cannot easily float above the hot metal bath, and as a result, it can spend some time staying in the hot metal. Therefore, according to the hot metal desulfurization apparatus according to the present invention, it is possible to improve the desulfurization rate.

In addition, some of the desulfurizing agent blown from the impeller installed in the upper stage rides in the downward flow or horizontal flow.
Some substances do not participate much in the desulfurization reaction, and at first glance it may not be necessary from the perspective of improving the desulfurization rate. It is desirable to accelerate the desulfurization reaction by blowing

Furthermore, in order to improve the desulfurization rate by installing the impeller in two stages, upper and lower, according to the findings of the present inventors, it is necessary to install the impeller in two stages, upper and lower, as shown in Figure 3. When the distance between the impellers installed in this way is H, and the height I of the impeller is h, it is more effective that H≧h...■.

In addition, the hot metal desulfurization equipment according to the present invention has a JR mechanism for switching the rotational direction of the rotating shaft that supports the impeller blades, and the impeller can rotate in forward and reverse directions, so both sides of the impeller blades have equal operating opportunities. Therefore, the degree of melting loss is also uniform on both sides. In other words, in the steady flow in conventional hot metal desulfurization equipment, the flow of hot metal in the vertical direction in the hot metal ladle (
However, in the hot metal desulfurization equipment according to the present invention, the rotation of the impeller (flow of hot metal) is stopped after a certain period of time, for example, 2 to 3 minutes, and the desulfurization agent is blown into the bottom of the impeller. The upstream and downstream flow of the molten pig iron is caused by the upward flow of the blown gas, and then the direction of rotation of the impeller is reversed. In this manner, the desulfurization apparatus according to the present invention can desulfurize hot metal.

Note that the number of revolutions of this impeller does not need to be limited to a specific value or range of values, but it should not be increased unnecessarily.If the number of revolutions becomes too high, as shown in Figure 4, This is because if the bulge at the edge of the hot metal scene becomes too large and exceeds the freeboard, the hot metal will overflow into the hot metal pot. Conventionally, the upper limit of rotation was determined by investigating this swelling in advance.

On the other hand, in the hot metal desulfurization apparatus according to the present invention,
The essential purpose of rotating the impeller is to stir the hot metal using the relative speed difference that occurs between the hot metal and the impeller. The resulting speed difference becomes smaller, and the stirring effect becomes smaller. For this reason, the impeller is rotated with a substantially constant speed difference between the impeller and the hot metal, and when there is no longer any freeboard margin due to the rise of the hot metal, the impeller is rotated in the reverse direction in the same manner as above, and the speed difference is All you have to do is make it come alive.

For example, as shown in Fig. 5(a), (1) Measure the moving speed of the slag at the zero point on the hot water surface using the ITV, and compare the measured speed with, for example, 1 m/s to 1.5 stiffness/S.
The rotational speed of the impeller is controlled by giving a speed difference of .

■ ITν monitors the scene where the impeller has risen to the point ■ on the top surface of the free board, and reduces the impeller rotation speed and reverses the rotation direction. An example of changes in the rotation speed of the impeller and the flow rate of hot metal at this time is shown in No. 511(b) over time. As is clear from FIG. 5(b), the impeller is stopped and reversed when the difference between the number of revolutions of the impeller and the flow velocity of the hot metal becomes small.

Next, J! of hot metal according to the present invention! The 52 sulfur sulfur device will be described in further detail with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view showing the configuration of one embodiment of the hot metal desulfurization apparatus according to the present invention, and FIG. ) is a schematic cross-sectional view of.

1 and 2, an impeller 5 consisting of two stages of upper and lower impeller blades 6.6 having a coaxial vertical rotation shaft 4 is located approximately in the center of hot metal 1 housed in a container such as a hot metal ladle 3. Provided so that it is located. Then, pressurized gas (carrier gas) and desulfurizing agent 2 are injected into the hot metal from jet ports 9 on both sides of the blade surface 7 of the impeller blade 6 through gas holes 8 provided in the rotating shaft 4 and the impeller 5, respectively. This is intended to maximize the catalytic reaction between the hot metal and the desulfurizing agent through stirring.

That is, in this embodiment, as shown in FIG. 2, the impeller blades 6 are made to protrude from the rotating shaft 4 which is made of refractory or heat-resistant treated so that the horizontal cross section becomes a cross, forming a cross-shaped impeller 5. One or more jet ports 9 are provided on both sides of the blade surface 7 of the impeller 6 , and the jet ports are communicated with gas holes 8 that pass from the rotating shaft 4 to the impeller blades 6 .

The pressurized gas is communicated to the gas hole in the rotary shaft 4 via a pressure regulating device by means of a storage tank or conduit.

The device according to the present invention is installed in a hot metal ladle 3 with the rotating shaft 4 vertically submerged approximately at the depth of the hot metal bath 1,
While coaxially rotating the impeller blades 6 provided in two stages, the desulfurizing agent is simultaneously suspended in the pressurized gas from the jet port 9 and jetted into the hot metal.

Due to the rotation of the impeller, which is installed in two stages (upper and lower), and the pressurized gas ejected from the blade surface in the rotation direction, reverse stirring occurs on the upper and lower surfaces in the height direction of the bath. The desulfurizing agent does not completely react and does not immediately float to the top of the bath, but remains suspended for a long period of time, and the desulfurizing agent is finely divided by the strong stirring motion of the hot metal formed by the hot metal desulfurization apparatus according to the present invention. Alternatively, sufficient dispersion can be achieved, and advantageous muco desulfurization can be promoted by increasing the chance of reaction with hot metal and increasing the reaction interface area due to the increased chance.

Regarding the jetting of the powdered desulfurizing agent from both sides of the impeller blade 6 using pressurized gas, the turbulent energy caused by the gas pressure is added to the turbulent energy caused by the stirring of the impeller from the front, and the powdered desulfurizing agent and reaction increases. The jetting from the rear surface of the impeller blade 6 is to blow the desulfurizing agent into the high-density inclined wall of the stirring process by the impeller, thereby increasing the desulfurizing efficiency.

In addition, by rotating the impeller blades 6, which are arranged in two stages (upper and lower), in a fixed direction and then in the opposite direction, for example, by performing forward and reverse rotation every 2 to 3 minutes, the impeller blades 6 can be Compared to constant direction rotation, a considerably better mixing and stirring state is generated, and at the same time, the impeller 5
The purpose is to prevent uneven wear due to melting of the refractory covering the impeller 5, extend the life of the impeller 5, prolong the stirring effect, and reduce repair costs.

Furthermore, by rotating the impeller 5 at a rotation speed that is about 20% higher than normal rotation, preferably about 10 to 20% higher, it is possible to sufficiently stir the negative layer and further improve the desulfurization efficiency.

This increase in rotational speed also has the effect of increasing the contact reaction with the desulfurizing agent due to strong stirring, and increases the desulfurization efficiency within the same processing time. This increase in rotation speed is the easiest method to do as long as the equipment's ability allows.
As mentioned above, it is important to set the rotational speed amplifier to a level that does not cause molten metal to scatter from the hot metal ladle due to rising bath level.

Furthermore, while referring to the results of Examples, the effects of the present invention will be explained.
Explain quantitatively.

The hot metal desulfurization device according to the invention, which uses a cross-shaped impeller whose horizontal cross section is a cross, as shown in FIG. 1, and the conventional hot metal desulfurization device shown in FIG. 6(b) are used. As shown in the table below, the present invention and the prior art were compared under the following processing conditions.

The processing conditions were: 250 tons of hot metal was added with 2.4 kg of desulfurization agent per ton of hot metal, the treatment time was 14 minutes, the impeller diameter was 275 mm, which was the diameter of the container, and the impeller depth was 172 mm, which was the hot metal bath depth. Stirring was performed at

The results are shown in Table 1.

As is clear from Table 1, the present invention has made it possible to significantly improve the conventional desulfurization efficiency.

(Effects of the Invention) As detailed above, the present invention solves the problems of conventional hot metal desulfurization equipment, is inexpensive, has strong stirring power, and can further extend the life of the impeller. It became possible to provide a hot metal desulfurization equipment.

The practical significance of the present invention having such effects is extremely significant.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the configuration of an embodiment of the hot metal desulfurization apparatus according to the present invention; FIG. 2 is a schematic horizontal cross-sectional view showing the configuration of an impeller used in the hot metal desulfurization apparatus according to the present invention; Fig. 3 is a schematic explanatory diagram showing the structure of an impeller used in the hot metal desulfurization equipment according to the present invention; Fig. 4 is a schematic diagram showing the hot metal bath surface during operation of the hot metal desulfurization equipment according to the present invention. Explanatory diagram: 5th
Figure (a) is a schematic explanatory diagram schematically showing a device that can automatically switch the rotation of the impeller of the hot metal desulfurization equipment according to the present invention; 3 is a graph showing the impeller rotation speed and the flow rate of hot metal over time for one example in which the apparatus shown in (a) was operated. FIG. 6(a) is a schematic perspective view showing the structure of a conventional impeller; and Part 6) is a schematic explanatory diagram showing the structure of a conventional hot metal desulfurization apparatus. 1; Hot metal 2: Desulfurization agent 32 ladle 4: Rotating shaft 5: Invera 6 = Impeller blade 7: Blade surface 8: Gas hole 9: Spout port No. 1 Figure 2 Encircle

Claims (3)

[Claims] (1) Hot metal desulfurization characterized by comprising a rotating shaft installed in a container that accommodates hot metal so as to be able to move in and out, and impeller blades for stirring the hot metal that are provided below the rotating shaft in two stages, upper and lower. Device. (2) The hot metal desulfurization apparatus according to claim 1, further comprising a rotation direction switching mechanism for the rotating shaft. (3) The hot metal desulfurization apparatus according to claim 1 or 2, wherein the impeller blade further has a desulfurizing agent jet port.