JP6555281B2 - Desulfurization slag reuse method and charging device - Google Patents

Description

  The present invention relates to a method for reusing desulfurized slag and a charging device.

  In the steel industry, the ratio of ultra-low sulfur steel is increasing due to the recent increase in demand for high purity and high functionality of steel materials. Thus, in the steelmaking process, a technique for further reducing the steelmaking cost and reducing the amount of slag generation is required for melting low sulfur steel. Generally, sulfur (S) is contained in the hot metal discharged from the blast furnace due to raw materials used in the blast furnace such as coke. Since sulfur is a component that basically has an adverse effect on the quality of steel, hot metal desulfurization and molten steel desulfurization are performed according to the required quality of steel. Among these, in hot metal desulfurization, a method of adding a refining agent mainly composed of cheap quick lime (CaO) to hot metal and stirring and mixing is used. In this case, the desulfurization reaction proceeds based on the reaction formula shown by “CaO + S → CaS + O”.

  By the way, in recent years, the promotion of resource saving and energy saving is required not only for the purpose of reducing manufacturing costs but also from the viewpoint of conservation of the global environment, and the reuse of desulfurized slag generated in the desulfurization process for lime-based desulfurization agents. (For example, Patent Document 1). In such a desulfurization slag reuse method, when desulfurization slag after hot metal desulfurization treatment by mechanical stirring desulfurization method is reused as a refining agent in other desulfurization treatment, desulfurization is performed using a heavy machine having a bucket. Slag is thrown into the hot metal.

Japanese Patent No. 5888952

  By the way, in the hot metal desulfurization process by the mechanical stirring type desulfurization method, the desulfurization process is performed by putting a refining agent mainly composed of quick lime into the hot metal and reacting the refining agent with the hot metal. At this time, the stirring blade provided in the mechanical stirring type desulfurization apparatus is immersed in the hot metal and is rotated so that the hot metal and the refining agent are stirred to promote the desulfurization reaction. The added refining agent forms desulfurization slag on the bath surface of the hot metal. In the mechanical stirring type desulfurization method, all of the CaO in the supplied refining agent does not react, and the desulfurized slag contains unreacted CaO. Generally, the desulfurization efficiency of a lime-based refining agent is about 10%, and the remaining 90% is considered not to contribute to desulfurization. For this reason, by adding this desulfurization slag as a refining agent in other desulfurization treatments, the amount of new desulfurization agent used can be reduced, and the amount of desulfurization slag generated can be suppressed. However, in the desulfurization treatment using desulfurization slag, there has been a problem that the desulfurization efficiency due to the desulfurization slag varies greatly and the desulfurization efficiency becomes low. In addition, further improvement in desulfurization efficiency is desired from the viewpoint of reducing manufacturing costs and reducing slag generation.

  Therefore, the present invention has been made paying attention to the above-mentioned problem, and provides a desulfurization slag reuse method and a charging device capable of improving the desulfurization efficiency in the desulfurization treatment using the desulfurization slag. It is aimed.

  According to one aspect of the present invention, in the desulfurization treatment of hot metal, a desulfurization slag reuse method in which desulfurization slag after desulfurization treatment is reused as a refining agent in other desulfurization treatment, When the desulfurized slag is charged, a method for reusing desulfurized slag is provided, wherein the desulfurized slag is charged using a bucket having a plurality of protrusions therein.

  According to one aspect of the present invention, there is provided a desulfurization slag charging device for charging desulfurized slag after desulfurization treatment into hot metal, an arm that is rotatably provided, and a pivotally attached to the tip of the arm, There is provided a desulfurization slag charging device comprising a bucket having a plurality of protrusions therein, and charging the desulfurization slag into the hot metal using the bucket.

  According to one aspect of the present invention, a desulfurization slag reuse method and a charging apparatus that can improve the desulfurization efficiency in a desulfurization process using desulfurization slag are provided.

It is explanatory drawing which shows the desulfurization slag injection | throwing-in process in one Embodiment of this invention. It is a perspective view which shows a bucket. It is a perspective view which shows a bucket. It is explanatory drawing which shows the grinding | pulverization condition of slag. It is explanatory drawing which shows a desulfurization process. It is explanatory drawing which shows a desulfurization slag discharge process. It is explanatory drawing which shows the modification of the reuse method of desulfurization slag. It is a graph which shows the desulfurization efficiency with respect to the novel lime addition amount in an Example.

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

<Desulfurization slag charging device>
First, a desulfurization slag charging apparatus according to an embodiment of the present invention will be described with reference to FIGS. The charging device 1 is a heavy machine such as a hydraulic excavator for charging the desulfurized slag 3 accommodated in the slag pan 2 to the molten iron 5 accommodated in the hot metal pan 4. The charging device 1 includes a lower traveling body 10, an upper swing body 11, a boom 12, an arm 13, two connecting portions 14 and 17, and a pair of buckets 15 and 16.

The lower traveling body 10 is a crawler traveling body. The upper swing body 11 has an engine or the like and is mounted on the lower traveling body 10 so as to be capable of swinging. The boom 12 is connected to the upper swing body 11 so as to be able to be raised and lowered. The arm 13 is connected to the boom 12 via the connecting portion 14 so as to be vertically rotatable.
The pair of buckets 15 and 16 are metal clamshell buckets, are provided facing each other, and are rotatably connected to the arm 13 via a connecting portion 17. As shown in FIGS. 2 and 3, the pair of buckets 15, 16 includes rectangular introduction ports 150, 160 and main body portions 151, 161 that can accommodate objects scooped up from the introduction ports 150, 160. Have each. Further, the pair of buckets 15 and 16 are opened and closed by rotating around the connecting portion 17 by a driving mechanism (not shown). Further, the pair of buckets 15 and 16 includes a plurality of claw portions 152 and 162 and a plurality of protrusions 153 and 163, respectively.

  The plurality of claw portions 152 and 162 are metal claw-like members provided at the tips of the buckets 15 and 16 on the side opposite to the connecting portion 17 and are fixed to the main body portions 151 and 161 by welding. The plurality of protrusions 153 and 163 are metal round bars (φ32 mm, height 100 mm), and are fixed to the tip side inside the bottom surfaces of the main body portions 151 and 161 by welding. The plurality of protrusions 153 and 163 are arranged in two rows arranged in a staggered manner in the width direction of the main body portions 151 and 161 (the front-rear direction in FIG. 1).

<Reuse method of desulfurization slag>
Next, a method for reusing desulfurized slag according to this embodiment will be described.
First, as shown in FIG. 1, the desulfurization slag 3 accommodated in the slag pan 2 is charged into the hot metal 5 accommodated in the hot metal pan 4 using the charging device 1 (desulfurization slag charging step). The desulfurization slag 3 is slag generated by a desulfurization process performed in advance, and is collected in the slag pan 2 in a desulfurization slag discharge process described later. In the desulfurization slag charging step, as shown in FIG. 1, the desulfurization slag 3 is agitated by opening and closing the pair of buckets 15 and 16 in the desulfurization slag 3 accommodated in the slag pan 2 in advance. Thereby, as will be described later, the aggregate forming the desulfurized slag 3 is pulverized. After the desulfurization slag 3 is stirred, the desulfurization slag 3 accommodated in the slag pan 2 is scooped up by the pair of buckets 15 and 16 of the charging device 1 and the pair of buckets 15 and 16 are closed (the inlets 150 and 160 are closed). In the closed state, the metal is moved above the hot metal 5. And the desulfurization slag 3 accommodated in the main-body parts 151 and 161 is made into the lower side of the inlets 150 and 160 by making the pair of buckets 15 and 16 open (a state where the inlets 150 and 160 are opened). Drop and throw in. At this time, the desulfurization slag 3 accommodated in the main body portions 151 and 161 falls while colliding with the protrusions 153 and 163 inside the main body portions 151 and 161.

  Here, in the mechanical stirring desulfurization method using a refining agent mainly composed of quicklime, the refining agent is generally in the form of a powder of about several hundred μm to several mm, although it varies depending on the charging method. Such a refining agent aggregates during the desulfurization treatment to form an aggregate of several mm to several tens mm. As shown in the sectional view of FIG. 4A, the desulfurization slag 3 is mainly composed of this aggregate, and the outer side is reacted CaO, but the inner side is unreacted CaO. When the desulfurization slag 3 is reused, as shown in FIG. 4B, it is important to pulverize the aggregate and perform a desulfurization process in a state where unreacted CaO is exposed on the surface.

  In the present embodiment, first, the desulfurized slag 3 can be pulverized to some extent by stirring the desulfurized slag 3 in the slag pan 2. At this time, the desulfurization slag 3 can be effectively pulverized by stirring with a pair of buckets 15 and 16 having a plurality of claw portions 152 and 162 at the tips. However, since the pulverization of the desulfurized slag 3 in the slag pan 2 is performed by the charging device 1 which is a large heavy machine, it is difficult to uniformly pulverize the desulfurized slag 3 in the slag pan 2. . For this reason, in this embodiment, when the desulfurization slag 3 is introduced into the molten iron 5, the pair of buckets 15 and 16 provided with a plurality of protrusions 153 and 163 are used so that the desulfurization slag 3 is provided at the time of introduction. It collides with the plurality of protrusions 153 and 163 and is crushed. Thereby, the desulfurization slag 3 is further pulverized, and the desulfurization slag 3 that could not be pulverized during pulverization in the slag pan 2 is also pulverized.

  After the desulfurization slag charging process, as shown in FIG. 5, the hot metal 5 is desulfurized using a mechanical stirring desulfurization apparatus 6 (desulfurization process). In the desulfurization step, the refractory stirring blade 60 is immersed in the hot metal 5 and rotated, so that the desulfurization slag 3 and the new lime-based refining agent introduced in the desulfurization slag injection step are in contact with the hot metal 5. Desulfurization reaction proceeds. In addition, when desulfurization can fully be performed only by the desulfurization slag 3 thrown in at the desulfurization slag addition process, a new refining agent does not necessarily need to be used. That is, in this embodiment, desulfurization slag 3 is thrown in as a refining agent, and desulfurization processing is performed by adding a lime type new refining agent as needed. In addition, as a refining agent, the additive containing components, such as CaF, Al, Si, and Mg, may be further included in order to promote melting of CaO and improve desulfurization efficiency.

  After the desulfurization step, as shown in FIG. 6, the desulfurization slag 3 after the desulfurization treatment is scraped out by the metal scraper 7 and discharged from the hot metal ladle 4 (desulfurization slag discharge step). The desulfurization slag 3 discharged from the hot metal ladle 4 is accommodated in the slag pan 2 disposed below the hot metal ladle 4. And the desulfurization slag 3 accommodated in the slag pan 2 is used in the desulfurization slag charging step, and is reused for the desulfurization treatment of the other hot metal 5.

<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. By referring to the description of the present invention, other embodiments of the present invention will be apparent to those skilled in the art, including various modifications along with the disclosed embodiments. Therefore, it should be understood that the embodiments of the present invention described in the claims also include embodiments including these modifications described in the present specification alone or in combination.

  For example, in the desulfurization slag charging step, the desulfurization slag 3 is stirred in the slag pan 2 using a pair of buckets 15 and 16 in advance, but the present invention is not limited to this example. For example, the desulfurized slag 3 may be directly charged into the hot metal 5 without stirring the desulfurized slag 3 in the slag pan 2. In the desulfurization process, there may be a case where sufficient time for stirring the desulfurization slag 3 cannot be taken due to time constraints. Even in such a case, the desulfurization slag 3 can be pulverized by charging the desulfurization slag 3 using the pair of buckets 15 and 16 in the above embodiment. Further, for example, when the desulfurized slag 3 is stirred in the slag pan 2, as shown in FIG. 7, the desulfurized slag 3 is scooped up using a pair of buckets 15 and 16 in the slag pan 2 (FIG. 7). The desulfurization slag 3 may be pulverized by performing an operation of (a) and FIG. 7 (b)) and dropping (FIG. 7 (c)). By performing the operation shown in FIG. 7 in addition to the stirring operation, the desulfurized slag 3 can be pulverized more uniformly.

In the above-described embodiment, the plurality of round bar-shaped protrusions 153 and 163 are provided in two rows in a staggered manner along the width direction of the main body portions 151 and 161, but the present invention is not limited to this example. As described above, the plurality of protrusions 153 and 163 collide with the desulfurization slag 3 when the desulfurization slag 3 is charged, thereby pulverizing the desulfurization slag 3. For this reason, the plurality of protrusions 153 and 163 are appropriately formed in consideration of the capacity of the pair of buckets 15 and 16 and operational problems (for example, costs for manufacturing and maintenance, etc.) It is preferable to be provided so as to be arranged. In consideration of pulverization descending, cost of members, ease of attachment, etc., the plurality of protrusions 153 and 163 are cylindrical ones having an outer diameter of 20 mm to 80 mm and a height of 50 mm to 200 mm. It is preferable to use it.
Furthermore, in the said embodiment, although the bucket of the injection device 1 was said to be a pair of clamshell type buckets 15 and 16, this invention is not limited to this example. For example, the bucket of the charging device 1 may be one bucket having the same shape as the buckets 15 and 16.

<Effect of embodiment>
(1) The method for reusing desulfurized slag 3 according to one aspect of the present invention is a method for reusing desulfurized slag in which desulfurized slag 3 after desulfurization is reused as a refining agent in other desulfurization in the desulfurization treatment of hot metal 5. It is a usage method, and when desulfurization slag 3 is thrown into hot metal 5 before desulfurization processing, desulfurization slag 3 is thrown in using buckets 15 and 16 which have a plurality of projection parts 153 and 163 inside.
According to the configuration of (1) above, when the desulfurized slag 3 is introduced into the hot metal 5, the desulfurized slag 3 can be crushed by colliding the desulfurized slag 3 against the plurality of protrusions 153 and 163. For this reason, since unreacted CaO is exposed on the surface of the desulfurized slag 3 as compared with the case where the desulfurized slag 3 is charged using conventional buckets 15 and 16 having no projections on the inside, desulfurization is performed. The desulfurization efficiency in the treatment can be improved. Furthermore, by improving the desulfurization efficiency, the amount of new refining agent used can be suppressed and refining costs can be reduced. Moreover, the generation amount of desulfurization slag 3 can also be controlled.

(2) In the configuration of (1) above, clamshell type buckets 15 and 16 are used.
According to the configuration of (2) above, a large amount of the desulfurized slag 3 can be introduced as compared with a single bucket. Moreover, since it becomes easy to stir the desulfurization slag 3 in the slag pan 2, the desulfurization slag 3 can be pulverized more.

(3) In the configuration of the above (1) or (2), before the desulfurization slag 3 is charged, the desulfurization slag 3 accommodated in the slag pan 2 is scooped up by the buckets 15 and 16, and the desulfurization slag 3 thus scooped up is obtained. The desulfurized slag 3 is pulverized by dropping it into the slag pan 2.
According to the configuration of the above (3), the desulfurized slag 3 can be pulverized more uniformly in addition to the above (1).

(4) The desulfurization slag 3 charging device 1 according to one aspect of the present invention is a desulfurization slag 3 charging device 1 for charging the desulfurized slag 3 after desulfurization treatment into the hot metal 5, and an arm that is rotatably provided. 13 and a bucket 15, 16 which is rotatably attached to the tip of the arm 13 and has a plurality of protrusions 153, 163 therein, and the desulfurized slag 3 is put into the hot metal 5 using the buckets 15, 16. .
According to the configuration of (4) above, the same effect as the configuration of (1) can be obtained. In addition, since the plurality of protrusions 153 and 163 need only be attached to the buckets 15 and 16 by welding or the like, the existing charging device can be applied at a low cost with a simple modification.

  Next, examples performed by the present inventors will be described. In the examples, the desulfurization slag 3 was reused by using the desulfurization slag 3 according to the above embodiment, and the desulfurization treatment was performed by reusing the desulfurization slag 3. Moreover, in an Example, the conditions (comparative example 1) which added the desulfurization slag 3 using a pair of buckets 15 and 16 without the projection parts 153 and 163, and performed the desulfurization process, and desulfurization slag 3 as a comparative example, The desulfurization efficiency was investigated also about the conditions (comparative example 2) which performed the desulfurization process without using. In addition, in the Example and the comparative example 1, the process which stirs the desulfurization slag 3 in the slag pan 2 using the pair of buckets 15 and 16 was similarly performed before the desulfurization slag charging step.

In addition, in Examples and Comparative Examples 1 and 2, as a processing condition, a new refining agent was added by natural dropping from a charging chute, and a processing time was 13 minutes. In addition, the hot metal 5 to be treated had a temperature of 1240 ° C. or more, a P concentration of 0.080 mass% or more, and an S concentration of 0.030 mass% or less. Furthermore, in Example and Comparative Example 1, the input amount of molten desulfurization slag 3 per molten iron ton was set to 3 kg / t or more and 7 kg / t or less.
In FIG. 8, the investigation result of the desulfurization efficiency of an Example and Comparative Examples 1 and 2 is shown. In FIG. 8, the horizontal axis is the amount of lime in the new refining agent per 1 ton of hot metal (new lime addition amount [kg / t]), and the vertical axis is the S concentration [mass% of hot metal before desulfurization treatment]. ] Is a desulfurization efficiency which is a value obtained by taking the natural logarithm of the ratio of the S concentration [mass%] after the desulfurization treatment.

  As can be seen from FIG. 8, when Example and Comparative Example 1 were compared, it was confirmed that the Example improved the desulfurization efficiency under the same amount of new refining agent used. In addition, the variation in the desulfurization efficiency in the example was smaller than that in the comparative example 1, and this tendency became remarkable particularly under the condition where the amount of the new refining agent used was small. This is considered to be because pulverization is not performed uniformly only by stirring in the slag pan 2, and a large aggregate may remain without being pulverized. However, it is shown that the example is more uniformly and finely pulverized by further pulverization using the protrusions 153 and 163 at the time of charging. In addition, although it can grind | pulverize more uniformly even if only stirring in the slag pan 2 takes time, in addition to having time restrictions in a normal operation form, the temperature of desulfurization slag 3 falls by stirring. Is a problem. As the desulfurization reaction is performed at a higher temperature, the desulfurization efficiency is higher. Therefore, when the temperature of the desulfurization slag 3 is decreased, the desulfurization efficiency is decreased.

In addition, when the example and the comparative example 2 were compared, it was confirmed that the desulfurization efficiency was improved in the example using the desulfurization slag 3 as the refining agent under the same usage amount of the new refining agent. It was.
Furthermore, the present inventors recovered the desulfurized slag 3 after the desulfurization treatment in Example and Comparative Example 1, and analyzed the cross section of the recovered desulfurized slag 3 with an electron beam microanalyzer (EPMA). The distribution of S in the desulfurized slag 3 was measured.
As a result of measurement using an electron beam microanalyzer, it was confirmed in the examples that S was distributed to the inside of the aggregate of the desulfurized slag 3 and it was confirmed that the pulverization was sufficiently performed. On the other hand, in Comparative Example 1, an aggregate of desulfurized slag 3 in which S was distributed only on the outside was confirmed, and it was confirmed that the pulverization was not sufficiently performed.

DESCRIPTION OF SYMBOLS 1 Loading device 10 Lower traveling body 11 Upper revolving body 12 Boom 13 Arm 14 Connection part 15,16 Bucket 150,160 Inlet 151,161 Main body part 152,162 Claw part 153,163 Protrusion part 17 Connection part 2 Slag pan 3 Desulfurization Slag 4 Hot metal ladle 5 Hot metal 6 Mechanical stirring desulfurizer 60 Stirring blade 7 Scraper

Claims (4)

In the hot metal desulfurization treatment, a desulfurization slag reuse method in which desulfurization slag after desulfurization treatment is reused as a refining agent in other desulfurization treatments,
When adding the desulfurized slag to the hot metal before the desulfurization treatment,
A method for reusing desulfurized slag, wherein the desulfurized slag is introduced using a bucket having a plurality of protrusions therein.   The method for reusing desulfurized slag according to claim 1, wherein a clamshell type bucket is used as the bucket. Before charging the desulfurized slag,
3. The desulfurization slag is pulverized by scooping up the desulfurization slag contained in a slag pot with the bucket and dropping the scooped desulfurization slag into the slag pan. 4. Of reusing desulfurized slag from the factory. A desulfurization slag charging device for charging desulfurization slag after desulfurization treatment into hot metal,
An arm provided rotatably,
A bucket rotatably attached to the tip of the arm and having a plurality of protrusions inside,
An apparatus for charging desulfurized slag, wherein the desulfurized slag is charged into the hot metal using the bucket.

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