JP2004190137A - Tilting type pouring trough for desiliconizing molten pig iron and method for desiliconizing molten pig iron using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilting type pouring trough capable of obtaining high desiliconizing reaction efficiency without requiring an independent vessel and an auxiliary device, further without any trouble even on a pig iron receiving operation of a carrying vessel by improving the tilting type pouring trough and to provide a desiliconizing method using the pouring trough. <P>SOLUTION: In the pouring trough used for the desiliconization of the molten pig iron at a casting floor for a blast furnace, a funnel shaped site is provided at an outlet part of the molten pig iron and a trough for conducting the molten pig iron to the carrying vessel is provided directly under the outlet of the funnel shaped site. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a slanting gutter used for pretreatment of hot metal that has been tapped from a blast furnace cast bed prior to subjecting it to converter refining and the like, and a desiliconization method using the same, and particularly to a blast furnace cast bed desiliconization method for hot metal. And a desiliconization method using the same.

  The hot metal removed from the blast furnace usually contains 0.2 to 0.8% by mass of silicon. When this hot metal is fed as it is to the subsequent steelmaking process to remove silicon by oxidation, the efficiency of removing phosphorus and carbon that are simultaneously oxidized is reduced. Therefore, in recent years, it has become popular to add a desiliconizing agent to hot metal in a blast furnace cast floor to remove silicon.

  In most cases, the desiliconization treatment in the blast furnace cast floor is performed by using an iron oxide-based desiliconizing agent in the flowing hot metal in a slanting gutter that pours hot metal from a hot metal gutter into a topping car or hot metal ladle that is a receiving (transport) container. Is added to oxidize the silicon contained in the hot metal and transfer it to slag. This method is particularly called a cast-bed desiliconization method, as distinguished from desiliconization performed in a steelmaking process.

  In recent years, the level of impurities in steel products has become strict, and refining to lower levels than ever has been pursued. In the case of silicon, it is required to reduce the concentration to 0.1% by mass or less in the blast furnace cast floor in order to efficiently remove phosphorus in the subsequent steelmaking process. In response to this requirement, operations are also being pursued in which the content of silicon in the hot metal discharged from the blast furnace stably becomes 0.3% by mass or less.

  However, when removing such a low level of silicon, the proportion of iron oxide consumed in the oxidation reaction of silicon is further reduced. As a result, it is necessary to further improve the reaction efficiency in the casting bed desiliconization treatment.

Broadly dividing the cast floor desiliconization method,
(1) Method of spraying desiliconizer in hot metal gutter,
(2) a method of spraying a desiliconizing agent in the inclined gutter,
(3) a method of spraying a desiliconizing agent upward in a downspout gutter,
(4) There is a method of injecting a desiliconizing agent into a deep-bottom desiliconization tank provided in a hot metal gutter. In the injection method (4), the injection lance is greatly worn and it is difficult to maintain and maintain the hot metal gutter, so the spraying method (1) or (2) or the spraying method (3) is not suitable. Mainly employed.

  In the above-mentioned methods (1) to (3), the desiliconizing agent does not react 100% with the silicon in the hot metal, and a part of the desiliconizing agent is converted into slag without being reacted. The slugized silicifying agent flows into the transfer container via the outlet of the inclined gutter. The slag that has naturally fallen with the hot metal is agitated in the vessel by the potential energy of the falling flow, and the desiliconization reaction further proceeds.

  In other words, the desiliconization reaction occurs in the casting bed desiliconization treatment is in the hot metal gutter, the inclined pouring gutter, and the transfer vessel. The main ones are in the inclined gutter and the transport container. The reaction in the transport container relies on stirring by natural fall. Therefore, it is a stirring and mixing in the vicinity of a so-called waterfall pot of a falling flow, and its control is difficult. In other words, the key to improving the reactivity in the cast floor desiliconization process is how to improve the reactivity in the inclined gutter.

  In order to improve the reaction efficiency under the same supply amount and supply rate of the desiliconizing agent, the contact area between the desiliconizing agent and the hot metal may be increased. For this purpose, it is necessary to disperse the desiliconizing agent to increase the mixing with the hot metal. However, as described above, the desiliconizing agent injected in the hot metal gutter or the inclined pouring gutter is slagged and aggregates before reaching the outlet of the inclined pouring gutter. In order to increase the contact area between the coagulated slag-forming desiliconizing agent and the hot metal, a strong stirring force is required.

  Methods such as mechanical stirring and gas stirring are typically used to provide this stirring force. However, in a high-temperature flow system such as a tilting gutter, these methods are difficult to use in terms of durability. Then, the following technology using the potential energy of the blast furnace cast floor is disclosed.

  Patent Literature 1 discloses an iron receiving guide having a cylindrical outlet for vertically flowing hot metal at an outlet of a tilting gutter, forming a hot metal pool in the iron receiving guide, and allowing the hot metal to naturally drop from the cylindrical outlet. A technique has been disclosed in which a vortex is generated to improve stirring and mixing.

  Patent Literature 2 discloses that a container capable of generating a swirling flow by utilizing the falling energy of hot metal at the time of hot metal outflow is used, and a desiliconizing agent containing iron oxide is involved in the swirling hot metal to improve reaction efficiency. A technique for causing this to occur is disclosed.

  These technologies use the falling energy of hot metal to generate swirl (swirl flow) to mix hot metal and desiliconizer, and the effect can be obtained only with a vessel shape without external operation. . However, in the former case, the hot metal flows down vertically from the pig receiving guide, and in the latter, the hot metal is discharged below the swirl flow generating vessel and poured into the pig receiving (transport) vessel. .

  That is, when such an operation is performed, the pig iron receiving guide and the swirling flow generating container are located immediately above the pig iron receiving (transport) container, and the upper part is covered. As a result, not only is it difficult to monitor the inside of the pig receiving (transport) container, but also equipment that measures from the upper part of the container such as a weight type level meter or a microwave level meter cannot be used. In the case of a transport container having a relatively small container opening, such as a topped car, the effect is particularly large.

Further, in the latter, the embodiment shows that a dedicated container is used as an aspect of the invention.However, when a dedicated container is introduced, it is inevitable to introduce ancillary equipment for supporting the container, It is disadvantageous in terms of equipment costs and maintenance.
JP-A-3-153810 JP 2001-40410 A

  The present invention is directed to a decanter gutter capable of obtaining a high desiliconization reaction efficiency without the need of an independent vessel or ancillary equipment by improving the decanter gutter, and without any hindrance to the receiving operation of the transport container, and a degasser using the same. It is an object of the present invention to provide a siliconizing method.

  Means for Solving the Problems To solve the above-mentioned problems, the present inventors have conducted intensive studies with an eye on improvement of the shape of the inclined gutter, and have embodied the results in the present invention.

  That is, the present invention relates to a tilting gutter used for desiliconization of hot metal in a blast furnace cast floor, wherein the hot metal outlet has a brazing-shaped portion, and the gutter for guiding the hot metal to a transport container immediately below the outlet of the brazing-shaped portion. It is the inclined gutter characterized by having provided.

  In the present invention, the inclined gutter is a receiving chamber for receiving hot metal, and a brazing-shaped portion connected to the outlet thereof, and a streamline of the hot metal flow flowing from the receiving chamber to the brazing-shaped portion, It is preferred to decenter the axis of the exit of the solder-shaped part.

  Further, the funnel-shaped portions may be provided at both ends of the inclined pouring gutter.

Further, the present invention, in performing the desiliconization of hot metal in a blast furnace cast floor,
(a) It consists of an iron receiving chamber for receiving hot metal, and a funnel-shaped part connected to its outlet,
(b) decentering the streamline of the hot metal flow flowing from the receiving room into the brazing section and the axis of the exit of the brazing section,
(c) Using an inclined gutter provided with a gutter for guiding the hot metal to the transfer container immediately below the exit of the brazing portion, the volume flow rate of hot metal passing through the brazing portion relative to the exit diameter (m) of the brazing portion (m ³ / min) is in the range of 0.5 to 3.0.

  ADVANTAGE OF THE INVENTION According to this invention, a high desiliconization reaction efficiency can be obtained by improvement of an inclined pouring gutter, without the need of an independent container and ancillary equipment, and also without any trouble in the pig receiving operation of a transport container.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the present invention, only a part of the inclined gutter 4 is improved so that it can be easily applied to the existing equipment of the blast furnace cast floor as shown in FIG. That is, as shown in FIG. 2, a funnel-shaped portion 8 is provided in the inclined gutter. This eliminates the need to introduce dedicated auxiliary equipment as in the case of introducing a dedicated container. FIG. 3 is a sectional view taken along the line AA in FIG.

  At the same time, it is important to provide a gutter 10 for guiding the hot metal 11 to a transport container (for example, the topped car 5) immediately below the outlet 9 of the funnel-shaped portion of the inclined gutter 4. The hot metal 11 flowing out from the outlet 9 of the funnel shape portion has vortex inertia and flows out in the circumferential direction of the outlet. Therefore, some kind of guide is necessary. However, if the guide is such that the hot metal 11 is guided vertically below as in the above-described prior art, it becomes difficult to control the receiving of hot metal.

  In the present invention, there is provided a gutter 10 which is connected immediately below the outlet 9 of the solder-shaped portion and feeds the hot metal 11 horizontally or obliquely downward. As a result, the inclined gutter 4 is no longer located immediately above the transport container, so that it is possible to manage the receiving iron as before. The gutter 10 is desirably oriented in a range of 45 ° downward from vertical with respect to the vertical axis of the funnel-shaped portion 8.

  In addition, the inclined gutter 4 comprises a receiving chamber 7 for receiving hot metal 11 and a brazing-shaped part 8, a streamline of the molten metal flow flowing from the receiving chamber 7 into the brazing-shaped part 8, and an outlet 9 of the brazing-shaped part. Is preferably eccentric with respect to the axis. Normally, the inclined pouring gutter 4 receives the hot metal 11 falling from the hot metal gutter 2. However, if the falling hot metal 11 is directly introduced into the wax-shaped portion 8, the circumferential flow in the wax-shaped portion 8 is weakened, and the vortex flow is reduced. It is disadvantageous for formation. If the hot metal is once received in the hot metal receiving chamber 7 and then the hot metal 11 is guided substantially horizontally along the circumferential direction of the soldering portion 8, a vortex can be obtained very effectively. For that purpose, it is important to decenter the streamline of the hot metal flow flowing from the pig receiving room 7 into the brazing portion 8 and the axis of the outlet 9 of the brazing portion.

  Further, a funnel-shaped portion 8 may be provided at both ends of the inclined gutter 4. By providing at both ends, not only continuous processing is enabled, but also the symmetry of the inclined gutter 4 is obtained, so that the equipment is not overwhelmed.

Using the inclined pouring gutter 4 provided by the present invention, the ratio Q / D of the volume flow rate Q (m ³ / min) of the hot metal passing through the brazing section to the exit diameter D (m) of the brazing section is in the range of 0.5 to 3.0. By performing the desiliconization treatment of the hot metal 11 under such conditions as described below, it is possible to enjoy extremely high desiliconization reaction efficiency. If the above-mentioned ratio Q / D is less than 0.5, the hot metal flow will flow out without forming a vortex in the shape portion 8, and effective stirring and mixing will not be achieved. If the above-mentioned ratio Q / D is larger than 3.0, the molten metal 11 fills the brazing-shaped portion 8, and it is not possible to obtain an effective vortex for stirring and mixing.

  In the present invention, the desiliconization treatment in the blast furnace cast bed is disclosed. However, the present invention is naturally applicable to equipment for producing hot metal containing silicon by a smelting reduction method or the like.

[Example 1]
In a cast bed of a blast furnace 1 (a tapping amount of 9000 ton / day) schematically shown in FIG. 1, sintering dust as an iron oxide-based desiliconizing agent is lanced into a hot metal flow falling from a hot metal gutter 2 to a slanting gutter 4. 6 through which the silicon was desiliconized. The specific unit of desiliconizer was 20 kg / ton.

FIGS. 2 and 3 show a plan view and a sectional view of the used gutter 4. The ratio of the hot metal volume flow rate of 1 m ³ / min to the exit diameter of the funnel-shaped portion of 0.5 m was 2. In this way, the hot metal 11 was desiliconized, and the relationship between the tapping Si concentration and the desiliconization oxygen efficiency before the desiliconization treatment was investigated. This is an invention example. The desiliconization oxygen efficiency is calculated by the following equation.

De silicate oxygen efficiency _{(%) = 100 × O M} / O F
O _M : Amount of oxygen associated with Si desiliconized from hot metal (kg)
O _F: amount of oxygen in the de-珪剤(kg)
On the other hand, as a comparative example, a desiliconization treatment was performed in the same manner as the invention example except that the inclined pouring gutter 4 having no solder-shaped portion 8 was used, and the relationship between the tapping Si concentration before the desiliconization treatment and the desiliconization oxygen efficiency. investigated.

  FIG. 4 is a graph showing the relationship between tapping Si concentration and desiliconization oxygen efficiency. As is apparent from FIG. 4, it is clear that the use of the inclined gutter 4 of the present invention greatly increases the desiliconization reaction efficiency.

[Example 2]
A desiliconization treatment was performed in the same manner as in Example 1 except that in the cast bed of the blast furnace 1 (a tapping amount of 9000 ton / day) schematically shown in FIG. Was. The specific unit of desiliconizer was 20 kg / ton. The ratio of the hot metal volume flow rate of 1 m ³ / min to the exit diameter of the funnel-shaped portion of 1.0 m was 1.0.

  The desiliconization treatment was performed in this manner, and the relationship between the tapping Si concentration before the desiliconization treatment and the desiliconization oxygen efficiency was investigated. This is an invention example.

  On the other hand, as a comparative example, desiliconization treatment was performed in the same manner as in the invention example except that a sloped gutter having no brazing portion was used, and the relationship between the tapping Si concentration and the desiliconization oxygen efficiency before the desiliconization treatment was investigated. did.

  FIG. 5 is a graph showing the relationship between tapping Si concentration and desiliconization oxygen efficiency. As is clear from FIG. 5, it is clear that the desiliconization reaction efficiency is greatly increased by using the inclined pouring gutter of the present invention.

[Example 3]
The desiliconization treatment was performed in the same manner as in Example 1 except that in the cast beds of blast furnaces having different tapping amounts (tapping amounts of 2500 ton / day), inclined pouring gutters having different exit diameters at the shape of the solder were used. The specific unit of desiliconizer was 20 kg / ton. The ratio of the hot metal volume flow rate of 0.33 m ³ / min to the outlet diameter of the funnel-shaped portion of 0.4 m was 0.83.

  The desiliconization treatment was performed in this manner, and the relationship between the tapping Si concentration before the desiliconization treatment and the desiliconization oxygen efficiency was investigated. This is an invention example.

  On the other hand, as a comparative example, desiliconization treatment was performed in the same manner as in the invention example except that a sloped gutter having no brazing portion was used, and the relationship between the tapping Si concentration and the desiliconization oxygen efficiency before the desiliconization treatment was investigated. did.

  FIG. 6 is a graph showing the relationship between tapping Si concentration and desiliconization oxygen efficiency. As is clear from FIG. 6, it is clear that the desiliconization reaction efficiency is greatly increased by using the inclined gutter of the present invention.

[Example 4]
The desiliconization treatment was performed in the same manner as in Example 1 except that in the cast beds of blast furnaces having different tapping amounts (tapping amounts of 2500 ton / day), inclined pouring gutters having different exit diameters at the shape of the solder were used. The specific unit of the desiliconizer was 20 kg / ton. The ratio of the hot metal volume flow rate of 0.33 m ³ / min to the outlet diameter of 0.16 m of the funnel-shaped part was 2.1.

  The desiliconization treatment was performed in this manner, and the relationship between the tapping Si concentration before the desiliconization treatment and the desiliconization oxygen efficiency was investigated. This is an invention example.

  On the other hand, as a comparative example, desiliconization treatment was performed in the same manner as in the invention example except that a sloped gutter having no brazing portion was used, and the relationship between the tapping Si concentration and the desiliconization oxygen efficiency before the desiliconization treatment was investigated. did.

  FIG. 7 is a graph showing a relationship between tapping Si concentration and desiliconization oxygen efficiency. As is clear from FIG. 7, it is clear that the desiliconization reaction efficiency is greatly increased by using the inclined pouring gutter of the present invention.

FIG. 2 is a layout diagram schematically illustrating an example of equipment arranged on a blast furnace cast floor. It is a top view which shows typically the example of the inclined gutter of this invention. It is sectional drawing of the AA arrow in FIG. It is a graph which shows the relationship between tapping Si concentration and desiliconization oxygen efficiency. It is a graph which shows the relationship between tapping Si concentration and desiliconization oxygen efficiency. It is a graph which shows the relationship between tapping Si concentration and desiliconization oxygen efficiency. It is a graph which shows the relationship between tapping Si concentration and desiliconization oxygen efficiency.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Hot metal gutter 3 Skinmer 4 Inclined gutter 5 Topped car 6 Lance 7 Receiving room 8 Wax-shaped part 9 Exit of wax-shaped part
10 gutter
11 Hot metal

Claims (4)

  An inclined pouring gutter used for desiliconization of hot metal in a blast furnace cast floor, comprising a funnel-shaped portion at a hot metal outlet, and a gutter for guiding hot metal to a transfer vessel immediately below an outlet of the hot metal-shaped portion. A featured gutter.   The slanting gutter comprises a receiving chamber for receiving hot metal, and a wax-shaped part connected to the outlet thereof, a streamline of the molten iron flow flowing from the receiving chamber to the wax-shaped part, and an outlet of the wax-shaped part. The inclined gutter according to claim 1, wherein the inclined center is decentered.   The inclined pouring gutter according to claim 2, wherein the funnel-shaped portions are provided at both ends of the inclined pouring gutter. When performing desiliconization of hot metal on a blast furnace cast floor, it consists of an iron receiving chamber for receiving hot metal and a brazing section connected to its outlet, and the streamline of the hot metal flow flowing from the receiving chamber to the brazing section. Use a slanting gutter provided with a gutter that eccentricizes the axis of the brazing-shaped part and a gutter for guiding the molten metal to the transport container immediately below the outlet of the brazing-shaped part, and adjusts the brazing-shaped part to the outlet diameter (m) of the brazing-shaped part. A method for desiliconizing hot metal, wherein a ratio of a volume flow rate (m ³ / min) of hot metal passing through is in a range of 0.5 to 3.0.

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