JP2011184707A - Method for removing sulfur in reducing slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing sulfur in reducing slag, by which a sulfur component in the reducing slag can be easily and efficiently removed. <P>SOLUTION: In the method for removing the sulfur component from the reducing slag 1 generated in reducing refining in a steel making process, the reducing slag 1 which keeps molten state without being cooled after reducing refining is subjected to a bubbling treatment by blowing to the reducing slag 1, gas 2 for oxygen blowing containing at least oxygen, and the sulfur component is removed from the reducing slag. In the bubbling treatment, the temperature of the reducing slag 1 is kept at 1,300-1,750°C. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for removing sulfur from reduced slag, in which a sulfur component is removed from reduced slag generated during reduction refining in a steelmaking process.

In the steelmaking process, reductive refining is performed for the purpose of adjusting the components to remove sulfur components by adding a reducing agent or quicklime to molten steel. And at the time of this refining, reduction | restoration slag containing a sulfur component produces | generates.
Reduced slag produced during refining and refining was used as roadbed material through stabilization treatment such as aging treatment, but due to problems such as elution of harmful elements in the reduced slag, the entire amount could not be recycled. Some were disposed of by landfill. However, the disposal amount at the landfill site is close to the limit, and it will be difficult to dispose of it by landfill in the future.

Therefore, conventionally, a method for repeatedly using reduced slag has been sought. For example, it has been proposed to remove a sulfur component from reduced slag generated during reduction refining and use it again for reduction refining. .
For example, Patent Document 1 discloses a method for treating reduced slag in which the sulfur component in the reduced slag is reduced by performing a steam treatment in which the reduced slag is brought into contact with water vapor.
Further, Patent Document 2 discloses a sulfur removal method for used slag in which used slag is removed in a carbon dioxide gas atmosphere at a temperature of 900 ° C. or higher for 1 hour or longer to remove sulfur components in the used slag. Has been.

JP 2008-163391 A JP 2008-308754 A

  However, in the method disclosed in Patent Document 1, after the reduced slag is cooled, a process for removing the sulfur component is performed. Therefore, problems such as energy loss due to cooling and waiting for cooling time occur. Moreover, since the operation | work etc. which adjust reduction slag to the particle size suitable for water vapor | steam processing are required, there exists a problem also in work efficiency.

  In the method disclosed in Patent Document 2, the used slag taken out from the refining apparatus and cooled is heated to remove the sulfur component. For this reason, problems such as energy loss due to cooling and waiting for cooling time occur as in the case of Patent Document 1. Moreover, since it heats after cooling, energy efficiency is very bad. Moreover, since the operation | work etc. which adjust to a carbon dioxide gas atmosphere at the time of a heating are needed, there exists a problem also in work efficiency.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a sulfur removal method for reduced slag capable of easily and efficiently removing a sulfur component in the reduced slag.

The present invention is a method for removing sulfur from reduced slag that removes sulfur components from reduced slag generated during refining during steelmaking,
Bubbling treatment is performed by blowing a blowing acid gas containing at least oxygen into the reduced slag maintained in a molten state without cooling after the reductive smelting, and a sulfur component is removed from the reduced slag. It exists in the sulfur removal method of reduction | restoration slag (Claim 1).

In the method for removing sulfur from reduced slag according to the present invention, bubbling treatment is performed by blowing a blowing acid gas containing at least oxygen into the reduced slag containing the sulfur component generated during the reduction refining. By performing this bubbling treatment, the sulfur component in the reduced slag and the oxygen in the gas for blowing acid react to form SO ₂ (sulfur oxide) gas and are released from the reduced slag to the outside. Thereby, a sulfur component can be easily removed from the reduced slag by a very simple method.

  Further, in the present invention, the bubbling process is performed while maintaining the molten state without actively cooling the reduced slag in the molten state generated during the reduction refining. Therefore, problems such as energy loss and waiting for cooling time due to cooling of the reduced slag after the reduction and refining as in the prior art described above can be solved. Further, in performing the bubbling treatment, it is only necessary to input energy necessary for heating or the like for maintaining the molten state of the reduced slag. Can be significantly reduced, and energy can be used efficiently.

Moreover, the said reduced slag from which the sulfur component after the said bubbling process was removed can be reused in the reductive refining in the steelmaking process as a reducing agent (reduced slag for desulfurization) which removes the sulfur component in molten steel. As a result, the reduction slag can be used repeatedly.
Further, in the present invention, since the processing is performed while maintaining the molten state of the reduced slag, the reduced slag remains in the molten state after completion of the processing as shown in FIG. Then, it can be transferred to a smelting ladle or the like containing molten steel that requires new refining and reused as reductive slag for desulfurization. Thereby, unlike the prior art described above, since it is not necessary to heat the reduced slag from room temperature to a molten state at the time of reuse, further reduction in energy and efficient use of energy can be achieved.

  Thus, according to the present invention, it is possible to provide a sulfur removal method for reduced slag that can easily and efficiently remove sulfur components in the reduced slag.

Explanatory drawing which shows the procedure of the sulfur removal method of reduction | restoration slag in Example 1. FIG. FIG. 3 is an explanatory view showing equipment for a desulfurization test in Example 2. Explanatory drawing which shows the result of the desulfurization test in Example 2. FIG.

In the present invention, after the reductive refining, the reduced slag is maintained in a molten state without being actively cooled. The temperature of the reduced slag in the molten state after the reduction refining is, for example, in the range of 1400 to 1600 ° C., and this temperature range is maintained.
In addition, the bubbling process can be performed by, for example, transferring the molten reduced slag generated during the refining and refining to a container different from the container that has performed the refining and refining process.

In the bubbling treatment, it is preferable to make fine bubbles of the blowing acid gas blown into the reducing slag.
In this case, the area where the blowing acid gas contacts the reducing slag can be increased. Thereby, reaction with the sulfur component in the said reduction | restoration slag and oxygen in the said gas for blowing acids can be accelerated | stimulated.
In order to make the bubbles of the blowing acid gas fine, for example, the blowing acid gas may be blown using a pipe having a small inner diameter, a porous nozzle, or the like.

In the bubbling treatment, it is preferable to blow the blowing acid gas into the reducing slag rather than blowing the gas for blowing acid near the surface of the reducing slag.
In this case, the sulfur component in the reducing slag and the oxygen in the blowing acid gas can be reacted more reliably.

In the bubbling treatment, it is preferable to use air as the blowing acid gas.
In this case, the bubbling process can be performed at low cost by using inexpensive air (air) as the gas for blowing acid. In particular, when the reduced slag is in a high-temperature molten state, the sulfur component in the reduced slag and the oxygen in the blowing acid gas can be used without using oxygen gas or the like that is more expensive than air (air). Can be sufficiently ensured, and low cost can be realized by using inexpensive air (air). Thereby, the cost required for removing the sulfur component from the reduced slag can be reduced.
In addition to the air (air), the above-described oxygen gas or the like can be used as the blowing acid gas.

In the bubbling treatment, the temperature of the reducing slag is preferably maintained at 1300 to 1750 ° C. (Claim 3).
In this case, the fluidity of the reduced slag is improved, and the SO ₂ gas generated by the reaction between the sulfur component in the reduced slag and oxygen in the blowing acid gas is transferred from the surface of the reduced slag to the outside. It can be discharged smoothly. Thereby, a sulfur component can be efficiently removed from the reduced slag.

When the temperature of the reduced slag during the bubbling process is less than 1300 ° C., not only the required fluidity cannot be secured, but it may be difficult to maintain the molten state itself.
On the other hand, when the temperature of the reduced slag exceeds 1750 ° C., the bubbling treatment can be performed, but the energy efficiency may be deteriorated.
In order to maintain the reduced slag in the temperature range, the reduced slag may be heated or the like.

Example 1
A method for removing sulfur from reduced slag according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the method for removing sulfur from reduced slag in this example is a method for removing sulfur components from reduced slag 1 generated during reduction refining in the steelmaking process, and maintains a molten state without cooling after reductive refining. A blown acid gas 2 containing at least oxygen is blown into the reduced slag 1 to perform a bubbling process, and a sulfur component is removed from the reduced slag 1.
This will be described in detail below.

  As shown in FIG. 1 (a), after the reductive refining of the molten steel 10 in the steelmaking process, a reductive slag 1 that is in a molten state and contains a large amount of sulfur component is generated in the refining ladle 41 by reductive refining. At this time, the temperature of the reducing slag 1 is in the range of 1400 to 1600 ° C. In addition, the components of the reduced slag 1 of this example are as shown in Table 1.

Next, as shown in FIG. 1 (b), only the molten reduced slag 1 is transferred from the smelting ladle 41 to the slag melting furnace 42.
And the reduction | restoration slag 1 moved to the melting furnace 42 only for slag is heated so that it may become a temperature of 1300-1750 degreeC, and the temperature range is maintained.

Next, as shown in FIG. 1C, the blowing acid gas 2 is blown into the molten reduced slag 1 in the form of bubbles using the blowing acid pipe 43 to perform bubbling. In this example, air (air) was used as the blowing acid gas 2. In addition, as the gas 2 for blowing acid, oxygen gas etc. can also be used.
As a result, the sulfur component in the reducing slag 1 and the oxygen in the blowing acid gas 2 react to form SO ₂ gas 3 that is released from the reducing slag 1 to the outside. Then, the sulfur component is removed from the reducing slag 1.

  In the bubbling process, the bubbles of the blowing acid gas 2 are made fine by reducing the inner diameter of the gas blowing pipe 43 or attaching a porous nozzle to the tip of the gas blowing pipe 43. . Thereby, the area which the gas 2 for blowing acids contacts the reduction | restoration slag 1 can be enlarged, and the reaction with the sulfur component in the reduction | restoration slag 1 and oxygen in the gas 2 for blowing acid can be promoted.

Further, the blowing acid gas 2 is blown into the interior of the reducing slag 1 rather than near the surface. Thereby, the sulfur component in the reduction | restoration slag 1 and the oxygen in the gas 2 for blowing acids can be made to react more reliably.
Further, the blown acid gas 2 can be blown from the outside of the attached porous plug by attaching a porous plug made of a porous refractory to the bottom of the smelting ladle 41 or the like.

Next, the effect in the sulfur removal method of the reduction slag of this example is demonstrated.
In the method for removing sulfur from reduced slag of this example, bubbling treatment is performed by blowing a blowing acid gas 2 containing at least oxygen into reduced slag 1 containing a sulfur component generated during refining and refining. By performing this bubbling treatment, the sulfur component in the reduced slag 1 reacts with the oxygen in the blowing acid gas 2 to form SO ₂ gas 3 that is released from the reduced slag 1 to the outside. Thereby, a sulfur component can be easily removed from the reduced slag 1 by a very simple method.

  Moreover, in this example, the bubbling process is performed while maintaining the molten state without actively cooling the reduced slag 1 in the molten state generated during the reduction refining. Therefore, problems such as energy loss and cooling time waiting due to cooling of the reduced slag 1 after reduction and refining as in the prior art described above can be solved. Further, in performing the bubbling treatment, it is only necessary to input energy necessary for heating or the like for maintaining the molten state of the reduced slag 1, so that energy necessary for removing the sulfur component from the reduced slag 1 is sufficient. Can be significantly reduced, and energy can be used efficiently.

Moreover, the reduced slag 1 from which the sulfur component after the bubbling treatment has been removed can be reused as a reducing agent for removing the sulfur component in the molten steel 10 (reduced slag for desulfurization) in reduction refining in the steelmaking process. Thereby, the reduction slag 1 can be used repeatedly.
Moreover, in this example, since the process is performed while maintaining the molten state of the reduced slag 1, as shown in FIG. 1 (d), after the process is completed, the reduced slag 1 remains in the molten state and new refining is performed. It can be transferred to a smelting ladle 41 containing the necessary molten steel 10 and reused as reducing slag for desulfurization. Thereby, unlike the prior art described above, it is not necessary to heat the reducing slag 1 from room temperature to a molten state at the time of reuse, so that further energy reduction and efficient use of energy can be achieved.

  In the bubbling process, air is used as the blowing acid gas 2. By using inexpensive air (air) as the gas 2 for blowing acid, the bubbling process can be performed at low cost. Thereby, the cost required to remove the sulfur component from the reduced slag 1 can be reduced.

In the bubbling process, the temperature of the reducing slag 1 is maintained at 1300 to 1750 ° C. Therefore, the fluidity of the reduced slag 1 is improved, and the SO ₂ gas 3 generated by the reaction between the sulfur component in the reduced slag 1 and oxygen in the blowing acid gas 2 is smoothly transferred from the surface of the reduced slag 1 to the outside. Can be released. Thereby, a sulfur component can be efficiently removed from the reduced slag 1.

  Thus, according to this example, it is possible to provide a method for removing sulfur from reduced slag that can easily and efficiently remove sulfur components in the reduced slag.

(Example 2)
In this example, a desulfurization test was performed using the method for removing sulfur from reduced slag of the present invention, and the effect was confirmed.
In this example, as shown in Table 2, a plurality of reduced slags (Experimental Examples 1 to 3) having different initial components were prepared.
And as shown in Table 3, about each reduction | restoration slag (Experimental Examples 1-3), under different conditions (slag amount, heating temperature, gas for blowing acid, blowing acid time, gas amount (pressure / flow rate)), A desulfurization test was conducted using the method for removing sulfur from reduced slag of the invention.

Specifically, the desulfurization test of this example was performed as follows.
That is, as shown in FIG. 2, the molten reduced slag 1 was put into a slag-dedicated melting furnace 51 and heated to a predetermined temperature by a high-frequency heating device 52.

Next, as shown in the figure, the blowing acid gas 2 was blown into the reducing slag 1 from the gas cylinder 53 using the blowing acid pipe 54 having an inner diameter of 30 mm, and bubbling was performed. As a result, the SO ₂ gas 3 was released from the reducing slag 1 to remove the sulfur component. And in this example, the sulfur content in the reduction | restoration slag 1 was measured for every blowing acid time.
The results of this desulfurization test are shown in Table 4 and FIG.

Table 4 shows the sulfur content for each blowing acid time for each reduced slag (Experimental Examples 1 to 3).
FIG. 3 is a graph of the numerical values in Table 4, showing the relationship between the blowing acid time (minutes) and the sulfur content (mass%) for each reducing slag (Experimental Examples 1-3). (Graphs E1 to E3 in the figure).

From the results shown in FIG. 3, it was found that the sulfur component in the reduced slag can be easily and efficiently removed by using the method for removing sulfur from the reduced slag of the present invention. In this example, it was found that all of the experimental examples 1 to 3 could remove most of the sulfur component contained in the reduced slag in the blowing acid time of about 90 to 120 minutes.
Table 4 shows only the sulfur content of the reduced slag, but other components are not particularly changed, and can be reused without any problem as a reducing agent (reducing slag for desulfurization) that removes sulfur components in molten steel. I understood.

  Moreover, as shown in the figure, when comparing Experimental Example 1 (graph E1) using oxygen gas as the gas for blowing acid and Experimental Examples 2 and 3 (graphs E2, E3) using air (air), sulfur There was no significant difference in the removal effect. Thereby, even when air (air) was used as the gas for blowing acid, it was found that the sulfur removal effect was sufficiently obtained.

1 Reduced slag 2 Gas for blowing acid

Claims (3)

A method for removing sulfur from reduced slag, which removes sulfur components from reduced slag generated during refining during steelmaking,
Bubbling treatment is performed by blowing a blowing acid gas containing at least oxygen into the reduced slag maintained in a molten state without cooling after the reductive smelting, and a sulfur component is removed from the reduced slag. A method for removing sulfur from reduced slag.   The method for removing sulfur from reduced slag according to claim 1, wherein air is used as the gas for blowing acid in the bubbling treatment.   3. The method for removing sulfur from reduced slag according to claim 1, wherein, in the bubbling treatment, the temperature of the reduced slag is maintained at 1300 to 1750 ° C. 3.

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