Technical field
[0001]
The present invention, molten slag produced in the steel making process remains after temporarily held in the slag holding furnace in a molten state, to an electric furnace for use in the process of being reduced by injecting an electric furnace.
This application, on December 16, 2016, claiming priority on Japanese Patent Application No. 2016-244501 filed in Japan, the contents of which are incorporated herein.
BACKGROUND
[0002]
　In recent years, the demand for recycling of resources increases, desulfurization with converter or the like in the steel making process, along with separating and recovering valuable materials such as Fe and P from dephosphorization or slag generated by decarburization refining (steel slag) , how to re-use by reforming steel slag to the high quality of the slag have been developed.
[0003]
　For example, Patent Document 1, adding steel slag to steel melt melting furnace, heat and while modified steel slag by adding a reducing material, denatured slag is shifted Fe in the slag, Mn and P in the molten metal a first step of obtaining a, Mn and P in the molten metal is oxidized to shift sequentially modified slag, high Mn slag, second sequentially taking out the high P slag, slag processing method and a third step is disclosed there.
[0004]
　Patent Document 2, the carbon contained in the steel bath below the carbon content of 1.5 wt%, since the charged iron oxide content of 5 wt% greater than steel slag, carbonized steel bath by the introduction of carbon or carbon carriers to obtain the rate 2.0 wt% greater than steel bath, after which a method for reducing the oxides in the steel slag is disclosed. In this method, in order to suppress the foaming of slag accompanying the violent reaction between the steel bath ejected from (slag forming) and the furnace (overflow) when the slag-up, reduce the carbon content of the steel bath before the slag-on to relax the reaction rate at the time the slag is turned by placing is performed to a reduction treatment of the slag then raised the carbon content.
　Non-Patent Document 1, steel slag powder in an electric furnace was charged with carbonaceous material powder and slag reforming material powder, as a result of the reduction test of the slag is disclosed.
[0005]
　Patent Document 3, in order to melt modifying the illiquid steel slag at a low temperature, before and after the addition or spraying the modifier to the low fluidity of the steelmaking slag contained in the container, mechanical slag surface after stirring, using a heating burner and melted by heating a mixed layer of slag and modifier, a method of coagulating and discharging molten slag obtained from the container it is disclosed.
[0006]
　Molten slag of high temperature having flowability in Patent Document 4, temporarily held in the slag holding furnace, the molten slag layer to the molten iron layer in an electric furnace after having formed as a buffer zone, slag held in the molten slag layer it is described that pouring molten slag from the furnace.
[0007]
　Structure of Patent Document 4, since the use of an electric furnace, the reduction reaction, the slag - than the reaction between the molten iron, the reaction of iron in slag (FeO) carbon content (C) and becomes dominant. Therefore, even if the C concentration in the molten iron is as low as 1.5 wt%, without carburization, it is possible to perform the reduction treatment of the slag, it is superior in that it can improve work efficiency .
[0008]
　Furthermore, the structure of Patent Document 4, rather than directly fed to the molten slag in the electric furnace, temporarily held in the slag holding furnace disposed adjacent to the electric furnace, buffer the molten slag layer on the molten iron layer in an electric furnace on which is formed as a band, while adjusting the injection amount, because it gradually injecting molten slag, it is superior in that it can suppress the slag foaming during slag on.
CITATION
Patent Document
[0009]
Patent Document 1: Japanese Sho 52-033897 Patent Publication
Patent Document 2: Japanese Kohyo 2003-520899 JP
Patent Document 3: Japanese Patent 2005-146357 JP
Patent Document 4: Japanese Patent No. 5522320 Publication
Non-patent literature
[0010]
Non-Patent Document 1: Scandinavian Journal of Metallurgy, 2003; 32: P.7-14
Summary of the Invention
Problems that the Invention is to Solve
[0011]
　The slag treatment method of Patent Document 1, because a reduction treatment using a converter, the molten metal and slag are agitated. Therefore, when the high carbon concentration of the molten metal during slag turned slag slag foaming occurs in contact with the molten metal. To avoid this, after turning the slag to a low melt carbon concentration, to promote the reduction reaction, it is necessary to increase the carbon concentration of the molten metal by introducing carbon. Therefore, a large number of slag reduction treatment, Mn, it is necessary to perform repeated oxidation and extraction process P, work efficiency and productivity are concerned decreases.
[0012]
　Treatment in Patent Document 2 slag reduction method described, and subjected to reduction treatment using a converter, in order to increase or decrease the concentration of carbon in molten iron performs the reduction treatment of the slag, that the decarburization Noborinetsu and carburized reduction It will repeat the work efficiency and productivity are concerned decreases.
[0013]
　The reduction test disclosed in Non-Patent Document 1, the pulverized steel slag between solidified cold has processed, the method of Patent Document 3 also has processed the lower steel slag fluidity at low temperatures. In this case, in order to perform the reduction treatment of the slag, it is necessary to heat and melt the slag, there is a problem that energy consumption is high.
[0014]
　Furthermore, using an electric furnace having a slag holding furnace as in Patent Document 4, even when forming a molten slag layer as a buffer zone, depending injection volume or injection rate of the molten slag, molten slag layer in an electric furnace disturbance is, in contact with the molten slag immediately after injection with molten iron layer in the lower layer, slag foaming is there is a possibility to occur.
　In Patent Document 4, if the molten slag layer to adjust the slag injection amount from the slag holding furnace so that it is not disturbed, since it is necessary to lower the slag injection amount and injection rate, there is a problem that processing efficiency is lowered . The holding furnace for injecting a slug by tilting the furnace body, depending on the size of the holding furnace is difficult fine adjustments of the slag infusion rate. Therefore, by slug injection rate varies even infusion rate as set smaller, will temporarily injection rate is increased, there is a risk that slag foaming occurs.
[0015]
　The present invention has been made in view of the above problems, electricity can be prevented and the molten iron layer of molten slag and electric furnace immediately after being injected from the slag holding furnace is vigorously mixed to produce a large slag foaming an object of the present invention is to provide a furnace.
Means for Solving the Problems
[0016]
　That is, it is an aspect of the present invention is as follows.
(1) One aspect of the present invention includes a furnace body having an electrode, in an electric furnace having a slag holding furnace capable injected into the furnace body the molten slag by tilting holds the molten slag remains in the molten state there, the furnace body includes a cylindrical furnace wall, and the furnace lid provided at the upper end of the furnace wall, provided at a lower end of the furnace wall, deep bottom and a height with respect to the deepest portion of the deep bottom portion There 150mm above has a shallow bottom portion are the following regions 500 mm, a furnace bottom with, provided in the furnace lid, and slag inlet where the molten slag is poured from the slag holding furnace, the said slugs inlet has an overlap with the shallow bottom and plan view, the area ratio in plan view of the shallow bottom portion to the furnace bottom 5% or more, 40% or less.
(2) has been in an electric furnace according to the above (1), the furnace walls, and a cross-sectional shape of the annular-shaped body perpendicular to the height direction, has a protruding portion that protrudes in the radial direction of the body the shallow bottom portion provided at a lower end of the protruding portion, the slag inlet may be provided at the upper end of the projecting portion.
(3) it has been in an electric furnace according to the above (1), the furnace walls, the cross-sectional shape perpendicular to the height direction has a body of annular shape, the shallow bottom portion is provided at a lower end of the body it may be.
(4) above (1) to (3) are in the electric furnace as claimed in any one claim in the furnace lid or the furnace cover and provided on both of the furnace wall, the reducing material furnace, it may have a reduced material inlet to be introduced into the.
Effect of the invention
[0017]
　According to the electric furnace mentioned above, it is possible to prevent contact molten iron layer of molten slag and electric furnace immediately after being injected from the slag holding furnace can be prevented from where the molten slag and the molten iron layer is mixed vigorously . Therefore, it is possible to prevent the molten slag layer and the molten iron layer will generate a large slag foaming rapidly react.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018]
It is a process diagram showing a slag treatment process using an electric furnace [1] The present invention.
FIG. 2 is a longitudinal sectional view showing a slag holding furnace (holding position) and the furnace body according to the present embodiment.
3 is a longitudinal sectional view showing the slag holding furnace (injection position) and the furnace body according to the present embodiment.
It is a cross-sectional view in FIG 4A] furnace body line I-I shown in FIGS.
A cross-sectional view of the furnace body at a height 150mm from FIG 4B] furnace bottom, a graph illustrating the only shallow bottom and deep bottom.
5 is a longitudinal sectional view showing a slag holding furnace (injection position) and an electric furnace according to a second embodiment of the present invention.
6 is a cross-sectional view along line II-II of the electric furnace shown in FIG.
It is a diagram illustrating a simulation result of slag injection into [7] furnace body.
A diagram showing a slag injection amount and the CO generation amount on [8] furnace body is a diagram showing a case having no shallow bottom.
A diagram showing a slag injection amount and the CO generation amount of the [9] furnace body is a diagram showing a case having a shallow bottom.
10 is a diagram for explaining operation patterns in Examples and Comparative Examples of the present invention.
DESCRIPTION OF THE INVENTION
[0019]
　Reference will now be described in detail preferred embodiments of the present invention.
[0020]
　[1. Slag treatment process Summary
　First, referring to FIG. 1, an outline of the slag treatment process using an electric furnace according to an embodiment of the present invention.
[0021]
　As shown in FIG. 1, molten pig iron is produced using a blast furnace in ironmaking step (S1), pig iron is refined to steel by using a converter or the like in the steel making process (S2). Steel making process (S2), the sulfur in the hot metal, phosphorus, desulfurization to remove carbon and the like, dephosphorization, and each step of the decarburization, the remaining removal to component adjustment gases and sulfur such as hydrogen or the like in the molten steel a secondary refining step (S6) performing, comprising a continuous casting step of casting the molten steel in a continuous casting machine (S7).
[0022]
　Of steel making process (S2), mainly dephosphorization (S4), decarburization (S5) is performed in the converter. In a converter furnace, molten iron is refined by using a flux composed mainly of calcium oxide. In this case, C in the molten iron by oxygen blown into the converter furnace, Si, P, Mn and the like are oxidized, the oxide is produced as calcium oxide and ties slag. Furthermore, desulfurization, the dephosphorization, the step of decarburization (S3, S4, S5), components of different slag each (desulfurization slag, dephosphorization slag, decarburized slag) is generated.
[0023]
　In the description herein, collectively referred to as steelmaking slag slag generated in the steel making process. Steelmaking slag, including the desulfurization slag, de-phosphorus slag, decarburization slag. Also refers to the steelmaking slag in the high temperature molten state and the molten slag, similarly, the desulfurization slag in the molten state, respectively dephosphorization slag, decarburized slag, molten desulfurization slag, molten dephosphorization slag, and molten decarburization slag It referred to.
[0024]
　In slag treatment step (S10), the molten slag produced in the steel making process (S2), by leaving transported to the electric furnace from a converter furnace, continuous reduction melting reformed in an electric furnace in the molten state, Fe in the molten slag, recovering valuable matter such as P, the molten iron layer in the lower layer of the molten slag layer. In this case, in the electric furnace, Fe in the molten slag, the reduction processing of oxides of P, and the like, the processing for separating the granulated metallic iron (the iron) from the slag, as maintaining the basicity of the slag is carried out.
[0025]
　As a result, the high phosphorous molten iron is recovered containing phosphorus content or the like which is separated from the molten slag, molten slag is reformed reducing Kai, high-quality reduction slag substantial blast furnace slag is recovered. Reducing slag, FeO compared with the previous reduction, P 2 O 5 because of the low content of such can be recycled to the cement material, ceramic products and the like. Further, since the low expansion by adjusting the components such basicity of the molten slag is lowered, it can be used as roadbed material or aggregate.
[0026]
　Furthermore, subjected dephosphorization processing (S11) to recovered high phosphorous molten iron, by shifting by oxidizing the P in the molten iron in the slag, a high phosphorous molten iron is separated into high phosphate slag and molten iron. High phosphate slag, can be recycled as a phosphate fertilizers and phosphoric acid raw materials. Further, the molten iron is recycled to the steel making process (S2), it is charged into the converter or the like.
[0027]
　Or more, and an overview of the slag treatment process. The process of the various molten slag produced in the steel making process (S2), it is preferable to be processed molten dephosphorization slag. Melting dephosphorization slag is a lower temperature than the melting decarburization slag contains a large amount of granulated metallic iron and phosphoric acid. Therefore, the molten dephosphorization slag, rather than oxidation treatment, by melting modified by reduction treatment, recovery efficiency of valuable elements by the process (Fe, P, etc.) is increased. Therefore, in the following description, as a molten slag to be processed, an example of using mainly molten dephosphorization slag. However, as the molten slag of the present invention is not limited to molten dephosphorization slag, it is possible to use molten desulfurization slag, melt decarburization slag, etc., any steelmaking slag generated in the steelmaking process.
[0028]
　[2. Configuration of slag treatment equipment]
　Next, with reference to FIG. 2, the electric furnace 100 is described for use in the slag treatment process (S10) in the slag treatment process.
　In an electric furnace 100 S10, a furnace to form a molten slag layer 5 and the molten iron layer 6 therein.
[0029]
　As shown in the enlarged portion of FIG. 2, the electric furnace 100 includes a furnace body 1, the slag holding furnace 2 disposed diagonally above the furnace body 1 (the slag holding container).
　Means for introducing molten slag 4 into the slag holding furnace 2 is slag pot 3, reciprocates between the converter and the slag holding furnace 2 slag pot 3 are not shown. Molten slag 4 discharged from the converter is charged into the slag pot 3. Slag pot 3, after transporting the molten slag 4 from the converter to the slag holding furnace 2 is introduced into the slag holding furnace 2. Slag holding furnace 2 may be held by storing the molten slag 4 a molten state, the molten slag 4 was the holding by tilting the furnace body 1 is continuously or intermittently injectable.
[0030]
　Molten slag 4 which is retained in the slag holding furnace 2 does not need to be a complete molten state. Even if part solidifies, you have a whole can be injected into the furnace body 1 fluidity.
[0031]
　The furnace body 1, with auxiliary materials, such as reducing material and reformers carbonaceous material such as an electric furnace reduction of melting and reducing and reforming molten slag 4, for example, have the furnace tilting mechanism not a direct current electric furnace of stationary type. Hereinafter, an example of a stationary type DC electric furnace.
[0032]
　[3. Furnace Configuration 1
　Continuing 2, 3, with reference to FIGS. 4A and 4B,, to describe the configuration of the furnace body 1.
　2, 3, as shown in FIGS. 4A and 4B,, the furnace body 1 is provided with a furnace roof 13 provided at the upper end of the furnace wall 12 and the furnace wall 12, a furnace provided at the lower end of the furnace wall 12 and a bottom 11. Furnace bottom 11, each of the inner surface of the furnace wall 12, and furnace roof 13, refractories are lined. On one side of the furnace lid 13 slag inlet 14 is formed. Slag inlet 14 is connected to the spout portion 21 of the slag holding furnace 2. The furnace body 1 is sealed with the exception of the slag inlet 14, it can be kept in the furnace.
[0033]
　At the center of the furnace body 1, the upper electrode 15 and the furnace bottom electrode 16 are opposed vertically. DC power is applied to the upper electrode 15 and the furnace bottom electrode 16, by generating an arc discharge between the upper electrode 15 and the furnace bottom electrode 16, the energy required to reduce the molten slag 4 is supplied.
[0034]
　The furnace lid 13 can be provided with a reduced material inlet 31a. Reducing material inlet 31a is connected to a material supply device 31, 32. The furnace wall 12 may be provided with reduced material inlet 33a. Material supply device 33 is provided in the reducing material inlet 33a.
[0035]
　Reducing material inlet 31a, 33a is a location for supplying the auxiliary raw material such as the reducing material and reforming material necessary for the reduction treatment of the slag 4. Figure 2, is exemplified a structure in which a reducing agent inlet to both the furnace wall 12 and the furnace cover 13, the reducing material inlet may be provided only in furnace roof 13.
[0036]
　Reducing material, coke powder anthracite powder, finely divided carbonaceous materials such as graphite powder are used. Modifier mainly SiO in the slag 2 or Al, 2 O 3 is intended to adjust the concentration, silica sand, fly ash, and the like waste refractory powders can be used. Reducing material is also a suppression means when the slag foaming occurs.
[0037]
　Furnace bottom 11 has a deep bottom 11d, a bottom shallow shallow bottom 11a than the deep bottom 11d.
　Shallow portion 11a, during the slag treatment process, assuming that it has a portion exposed from the surface of the molten iron layer 6, it is installed.
　During slag processing, in addition to molten iron or molten steel in an electric furnace 100 together with the molten slag 4 is to be charged, for hot metal with the slag reduction is generated, increasing the height of the molten iron layer 6 to. When thickened is molten iron layer beyond a certain, as it reduces the height of the molten iron layer 6 by opening the tap hole 18 for discharging molten iron, the period after the reduction by exposing the shallow bottom 11a from the molten iron layer 6, in this state, to inject a molten slag 4 which then reduction treatment to the electric furnace 100, is assumed. However, not shallow portion 11a can not inject the molten slag 4 is not exposed from the molten iron layer 6, on the height of the molten iron layer 6 is shallow bottom part 11a, if lower than a certain level, the injected molten slag 4 since vigorous mixing is suppressed with the molten iron layer 6 and can achieve the object of the present invention.
　As the structure of the furnace body 1, FIG. 4A, the structure having a projecting portion 10b as shown in FIG. 4B (the first embodiment), the structure having no overhang portion 10b as shown in FIG. 6 (second it can employ embodiments). Here will be described an example of the first embodiment firstly.
　In the first embodiment, FIG. 4A, as shown in cross-sectional view of FIG. 4B, the furnace body 1, a main body portion 10a perpendicular sectional shape of the annular shape cylindrical in the height direction, the main body portion projecting radially outward from the 10a, it will be described and a projecting portion 10b.
　Shallow bottom 11a as part of the furnace bottom 11 during the slag treatment process, on the assumption that become above the thickness of the molten iron layer 6 is raised portions, for example, FIGS. 2 and 3 as shown in, the furnace bottom 11 at the projecting portion 10b is formed by shallower stepwise. Shallow bottom 11a is a refractory similar to the inner surface of the other portions of the furnace bottom 11.
　As shown in FIG. 4A, the shallow bottom portion 11a has an overlap with slag inlet 14 in plan view. In other words, in a plan view, the existence region of the existence region and slag inlet 14 of the shallow bottom portion 11a is partially or entirely overlap. Molten slag 4 which is injected from the slag holding furnace 2 into the furnace flows through the spout 29. Because spout 29 is in the region of the slag inlet 14, the molten slag flowing from the spout would fall toward the shallow bottom portion 11a. That is, the shallow bottom portion 11a would comprise a falling position of the molten slag 4 flowing down from the slag inlet 14. Thus, if the molten slag 4 is injected into the furnace body 1, molten slag 4 is injected toward the shallow bottom portion 11a.
　The projecting portion 10b, slag inlet 14 is formed in the furnace roof 13.
[0038]
　In Figure 2, the furnace bottom 11 that becomes one step shallower overhanging portion 10b, but shallow bottom 11a is formed, the shallow portion 11a is not limited to this shape. For example, the furnace bottom 11 may be formed shallow bottom part 11a that becomes shallow over two or more stages, the furnace bottom 11 is not a stepwise at projecting portion 10b, it becomes shallow to form a continuous slope in, shallow bottom 11a may be formed. Further, the shallow portion 11a may not necessarily have a horizontal surface as shown in FIG. Shallow bottom part 11a below the slag inlet 14, to the extent that the slag treatment process can be assumed that it is exposed from the molten iron layer 6, the overall shallow bottom 11a may be a stepped shape or slope shape. However, if the shallow portion 11a has a horizontal surface, without decreasing the furnace capacity than necessary, preferable in that it can secure an area ratio in a plan view of the shallow bottom part 11a against the bottom of the furnace 11 at least 5%.
[0039]
　As shown in FIG. 3, the basic assumption, if the molten slag 4 tilts the opening portion 21 side pouring slag holding furnace 2 is injected into the furnace body 1, which is injected from the slag inlet 14 molten slag 4 flows down into the molten slag layer 5. The molten slag layer 5 by flowing down molten slag 4 is disturbed, but run down place has shallow bottom 11a. Since the location of the shallow portion 11a no molten iron layer 6 below the molten slag layer 5, molten slag 4 immediately after the injection is not able to contact the molten iron layer 6. Therefore, molten slag 4 immediately after the injection, due to rapidly react with the molten iron layer 6, slag foaming is prevented.
[0040]
　As shown in FIG. 2, the shallow bottom portion 11a, the height H is 150mm or more for the deepest portion of the deep portion 11d, which is less area 500 mm. This, if there is 150mm or more height, newly molten slag 4 which is charged is effective to alleviate the situation in which vigorous mixing with molten iron layer 6 with the original is because expected. The reason why the height with respect to the deepest portion of the deep portion 11d is 500mm or less, while not meaning to be 500mm greater, because the so high that adverse furnace capacity decreases are concerned.
　As shown in FIG. 4B, S the area in plan view of the deep bottom 11d 1 , an area in plan view of the shallow bottom part 11a S 2 When the area ratio in plan view of the shallow bottom part 11a against the bottom of the furnace 11 (S 2 / (S 1 + S 2 ) × 100) is more than 5%, is preferably 40% or less. By area ratio is 5% or more, can be the ratio of molten slag layer 5 can enjoy a mixed relaxation effect is ensured, suppressing severe forming generation as a whole slag. If the area ratio is 40 percent, whereas it is hardly effect of suppressing the forming product is increased, and the molten iron capacity of the molten iron layer 6, the interfacial area between the molten iron layer 6 and the molten slag layer 5 becomes smaller , it is caused concern that the reduction efficiency is reduced. Moreover, since the shallow portion 11a exceeds 40% contained in the high current density region of the furnace bottom 11, because the shallow portion 11a is easily depleted.
　Incidentally, the shallow bottom portion 11a in the present invention "height H to the deepest portion of the deep portion 11d is 150mm or more, 500 mm or less in the region" because it is defined as, S 1 and S 2 the boundaries of the deepest portion of the deep portion 11d the height H to is the position of 150 mm.
[0041]
　Further, in FIG. 2, shallow portion 11a, although Chinsen the molten slag layer 5 while exposed from molten iron layer 6 may be exposed from the molten slag layer 5. In this case, molten slag 4 injected from the slag inlet 14, after impinging on the surface of the shallow bottom portion 11a, flows into the molten slag layer 5 flows down the surface of the shallow bottom portion 11a. By molten slag 4 collides with the surface of the shallow bottom part 11a, since the kinetic energy is attenuated, not be melted slag 4 in the molten iron layer 6 is mixed vigorously. Accordingly, it is suppressed that the molten iron and molten slag 4 is rapidly reacted, slag foaming is suppressed.
[0042]
　Incidentally, as shown in FIG. 2, the furnace wall 12, a tapping port 17 for discharging the reducing slag, it can be provided with a tap hole 18 for discharging molten iron. Dekasuguchi 17, the position corresponding to the molten slag layer 5, specifically is formed at a position higher than the upper surface of the shallow bottom portion 11a. Tap hole 18, the position corresponding to the molten iron layer 6, specifically is formed at a position lower than the upper surface of the shallow bottom portion 11a.
[0043]
　[4. Configuration of the slag holding furnace]
　Next, with reference to FIGS. 2 and 3, used in the slag treatment process according to the present embodiment will be described in detail the structure of the slag holding furnace 2.
[0044]
　As shown in FIG. 2, the slag holding furnace 2 holds the molten slag 4, a container of heat resistance to be injected into the furnace body 1. Slag holding furnace 2 can adjust the injection amount of the molten slag 4 to the furnace body 1, and is also a exhaust path of the exhaust gas generated in the furnace body 1.
　Slag holding furnace 2 is provided with a furnace body 20 for storing and holding the molten slag 4, the spout portion 21 for injecting molten slag 4 in the furnace body 20 to the furnace body 1.
[0045]
　Furnace body 20 is a container of sealed, having an inner space for storing the molten slag 4.
[0046]
　The furnace body 20, the gas discharge port 25 and the slag charging port 26 is formed. Gas outlet 25 is an exhaust port for discharging exhaust gas from the furnace body 1 through the slag holding furnace 2, is connected to the intake system of the dust collector, not shown. The intake system, the atmosphere in the slag holding furnace 2 is maintained at a negative pressure. Slag charging port 26 is an opening for introducing molten slag 4 from above the slag pot 3 into the furnace body 20. The slag charging port 26 is installed openable holding furnace lid 27, holding furnace lid 27 is opened at the time of introduction of molten slag 4. At a time of non-insertion of the molten slag 4, the holding furnace lid 27 is closed slag charging port 26 is closed to prevent outside air from entering the furnace body 20, the furnace body 20 is kept warm.
[0047]
　Spout portion 21 is a tubular that is provided on the furnace body 1 side of the furnace body 20. The internal space of the spout 21, the slug injection path 28, and the spout opening spout 29 formed at the tip of 21 to inject molten slag 4 from the furnace body 20 into the furnace body 1. Slag injection path 28 is curved downward as compared to the interior space of the furnace body 20 vertically and Rohaba direction has become smaller (the direction perpendicular to the plane of FIG. 2), toward the injection forward. It becomes gradually narrower as the inner space of the furnace body 20 even spout portion toward the 21 side. By the furnace body 20 and the spout portion 21 such a shape, when injecting the molten slag 4 in the furnace body 20 to the furnace body 1 becomes easy to adjust the injection volume.
[0048]
　Spout portion 21 of the slag holding furnace 2 is connected to a slag inlet 14 of the furnace lid 13 furnace body 1. In Figure 2, the spout portion to increase the inner diameter of the slug injection port 14 of the furnace body 1 than the outer diameter of 21, a structure for inserting the tip of the pouring spout portion 21 into the slag inlet 14, between them there is a slight gap. The structure for connecting the spout portion 21 and the slag inlet 14 is not limited to the structure in FIG. 2, for connecting the two airtight, or stuffed with filler in a gap therebetween ligated with bellows or the like etc., can be varied in many ways.
[0049]
　In closed state of the holding furnace lid 27, when the atmosphere not operate the dust collector (not shown) in the slag holding furnace 2 to a negative pressure state, the slag holding furnace 2 is an exhaust path of the exhaust gas generated in the furnace body 1 . Specifically, CO, and H generated by the reduction process of the furnace body 1 2 exhaust gas containing such, through the slag inlet 14 and the slag holding furnace 2 of the pouring spout portion 21 of the furnace body 1, the slag holding furnace 2 flowing into the furnace body 20. Since the slag holding furnace 2 is maintained at a negative pressure, even in the outside air from the gap of the connecting portion of the furnace body 1 and the slag holding furnace 2 enters, external exhaust gas of the furnace body 1 from the gap It does not leak in. Outside air enters from the gap is sucked into the slag holding furnace 2 side. Furthermore, the exhaust gas flowing into the slag holding furnace 2 is discharged from the gas discharge port 25 proceeds to the furnace body 20 is processed and reaches the dust collector (not shown).
[0050]
　Further, the lower portion of the slag holding furnace 2 of the furnace body 20, the tilting device 40 is provided.
[0051]
　Tilting device 40 is tilted to the opening 21 side poured slag holding furnace 2, a device for injecting the molten slag 4 spout portion 21 of the furnace body 20 into the furnace body 1.
　Tilting device 40, between the slag holding furnace 2 to the orientation around the tilt axis 44 (FIG. 2) and an injection position (Fig. 3), it is possible to tilt. And the holding position, as shown in FIG. 2, without slag holding furnace 2 injects molten slag 4 in the furnace body 1, a posture when holding the furnace body 20. And injection position, as shown in FIG. 3, the slag holding furnace 2 tilts the spout portion 21 side, is a posture at the time of injecting the molten slag 4 in the furnace body 20 into the furnace body 1.
[0052]
　When changing the injection position from the holding position the slag retaining furnace 2, to tilt the slag holding furnace 2 to furnace body 1 side around the tilt shaft 44. Thus, as shown in FIG. 3, the position of the spout portion 21 with respect to the furnace body 20 is relatively low, the molten slag 4 which is held in the furnace body 20 is, in the spout portion 21 side headed flows, flows down from spout 29 through slag pouring passage 28, is poured into the furnace body 1. At this time, by adjusting the tilting angle of the slag holding furnace 2, it is possible to adjust the injection amount of the molten slag 4.
[0053]
　The electric furnace 100 according to this embodiment has a shallow bottom portion 11a, can be effectively prevented slag foaming. Electric furnace 100 according to the present embodiment further, by tilting the slag holding furnace 2 using a tilting device 40, or intermittently injecting molten slag 4 in the furnace body 1 may or adjust the injection amount . During injection of the molten slag 4 to the furnace body 1, it was injected molten slag 4, rapidly reacts with the molten iron in the furnace body 1, so as not to overflow from the furnace body 1, injection volume with tilting device 40 appropriately adjusted (i.e., adjust the tilt angle of the slag holding furnace 2) while it is preferable to intermittently inject the molten slag 4. Upon injection of the molten slag 4, the injection speed is too high, the molten slag 4 is the forming state furnace body within 1, there is a case where an overflow may occur. In this case, by reducing the tilt angle of the slag holding furnace 2 by tilting device 40, or pause the injection of the molten slag 4, or by reducing the injection volume, calming the reaction in the furnace body within 1 it is preferable to.
[0054]
　Injection amount of the molten slag 4 per unit by slag holding furnace 2 time is determined in accordance with the reduction capacity of the furnace body 1. Reduction processing power, the power supply amount per unit time of the furnace body 1, for example, depends on the amount of electric power applied to the upper electrode 15 and the furnace bottom electrode 16 of the furnace body 1. Therefore, the electric power consumption rate required for the reduction process of slag 4, based on the applied actual amount of power to the upper electrode 15 and the furnace bottom electrode 16, may be determined injection amount of the molten slag 4 per unit time.
[0055]
　As a method of intermittently injecting a molten slag 4 from the slag holding furnace 2 to furnace body 1, a method of injecting while repeating interruption and injection of the molten slag 4 appropriately, at predetermined time intervals, to the slag holding furnace 2 there is a method of injecting together molten slag fourth predetermined amount held. Although it is possible to continuously inject the molten slag 4 from the slag holding furnace 2 to furnace body 1. When intermittently injecting molten slag 4, the total amount of molten slag 4 to be injected into one time, that overflows by slag foaming is an amount that does not occur, preferably confirmed in advance experimentally or the like.
[0056]
[5. Reduction treatment method] of the molten slag
　with reference to continue FIGS. 2 and 3, demonstrates the reduction process of the slag 4 using an electric furnace 100 in the above configuration.
　First, prior to the reduction treatment area S of the deep bottom 11d 1 to determine the H, based on the determined value, it is necessary to form a shallow bottom portion 11a.
　Specifically, (volume of total seed water and reduced iron) maximum volume of the molten iron layer 6 is S 1 S to be less than × H 1 to determine the H.
[0057]
　Next, as shown in FIG. 2, the first furnace body 1, as a seed hot water in advance accommodate Molten hot metal or the like which is transported from a blast furnace as a molten iron layer 6. C concentration molten iron is usually 1.5-4.5 wt%.
[0058]
　Then, after allowed to continuously operate to supply power to the furnace body 1, the reduction capacity of the furnace body 1 (for example, unit time per power supply amount to the furnace body 1) the amount of molten slag 4 in accordance with FIG. as shown in 3 is injected from the slag holding furnace 2 into the furnace body 1. Molten slag 4 which is injected into the furnace body 1, to form a molten slag layer 5 on the molten iron layer 6. Incidentally, injected molten slag 4 to fall toward the shallow bottom portion 11a, it is not in direct contact with the molten iron layer 6. Thus the presence of the shallow bottom part 11a, can be effectively prevented slag foaming.
　Additionally, auxiliary materials such as reducing agent (carbonaceous material) and a modifier also continuously charged into the molten slag layer 5 in the furnace body 1 through the raw material supply device 31, 32, 33. Moreover, in the furnace body within 1, temperature of the molten iron layer 6 is for example 1400 ~ 1550 ° C., is controlled to be a temperature of the molten slag layer 5, for example, 1500 ~ 1650 ° C.. This temperature control, and adjusting the supply amount of the molten slag 4 can be carried out by adjusting the electric power supplied without changing the molten slag supply.
[0059]
　As a result, in the furnace body within 1, as an energy source the arc heat between the upper electrode 15 and the furnace bottom electrode 16, the reduction reaction of the molten slag 4 of the molten slag layer 5 progresses. In this reduction process, the oxide contained in the molten slag 4 (FeO, P 2 O 5 , etc.), is reduced by C in the carbonaceous material in the molten slag layer 5, Fe, P is generated, the generated Fe , P is, transitions from the molten slag layer 5 in the molten iron layer 6. C surplus carbonaceous material is suspended in the molten slag layer 5 and eventually dissolves in molten iron.
[0060]
　In the reduction process described above, FeO contained in the injected molten slag 4, than C contained in the molten iron in the molten iron layer 6, preferentially reacts with C in the carbonaceous material in the molten slag layer 5 (FeO + C → Fe + CO ↑). That, C of thrown-in carbonaceous material, so suspended in the molten slag layer 5 without going to a molten iron layer 6, FeO + C → Fe + CO reduction reaction proceeds preferentially in the inside of the molten slag layer 5, is produced It was reduced iron (Fe) shifts to the molten iron layer 6.
[0061]
　Thus, in the reduction process by the furnace body 1, rather than the reaction of C of FeO and molten iron layer 6 in the molten slag layer 5, dominant found the following reaction between FeO and C in the molten slag layer 5 is there. Therefore, when injecting a molten slag 4 into the furnace body 1, the molten slag layer 5 on the molten iron layer 6, since the buffer zone for reaction with the injected molten iron in the molten slag 4 and molten iron layer 6, shallow coupled with the effect of providing the bottom 11a, it can suppress an abrupt reaction of the molten slag 4 and molten iron.
[0062]
　That is, the molten slag 4 by injecting a low melting slag layer 5 of FeO concentration, FeO concentration in the molten slag 4 being injected with possible dilution reduced, injected with molten iron in the molten slag 4 and the molten iron layer 6 is It is possible to suppress the direct contact. Thus, upon injection of the molten slag 4 from the slag holding furnace 2 into the furnace body 1, it is possible to suppress slag foaming due to rapid reaction between the molten slag 4 and molten iron, it can be avoided overflow.
[0063]
　As described above, oxides contained in the molten slag 4 which is injected into the molten slag layer 5 in the furnace body 1 is reduction treatment, since Fe and P is recovered in the molten iron layer 6 from the molten slag 4, FeO in molten slag 4, P 2 O 5 to reduce the slag component is modified. Accordingly, after injection of the molten slag 4, if traveling reduction treatment, components of the molten slag layer 5, is reformed gradually modified to the reducing slag (high-quality slag substantial blast furnace slag) from the molten slag 4 (steel slag) go. Molten slag layer 5 that has been modified in a reducing slag, since a more FeO low concentration buffer zone, a new molten slag 4 from the slag holding furnace 2 when injected into the molten slag layer 5, more slag forming it becomes possible to reliably suppress. Further, as a modifying material, SiO 2 source, Al 2 O 3 by addition of sources, it is possible to adjust the components of the molten slag.
[0064]
　Moreover, the injection rate and injection amount of the injected molten slag 4, there is a fear that the molten slag layer 5 is disturbed by molten slag 4, since the shallow portion 11a is provided, immediately after the injection molten slag 4 There not contact the molten iron layer 6. Therefore, molten slag 4 immediately after the injection due to rapidly react with the molten iron layer 6, slag foaming is prevented.
[0065]
　Furthermore, the shallow bottom part 11a of the furnace bottom 11, as the contact between the molten iron layer 6 of slug injection flow and electric furnace 100 is prevented, by the molten slag layer 5 (T.Fe) is increased, slag slag metal interface may react with C in the metal by generating CO gas, there is a case where it induces slag foaming. Reducing material inlet 31a in that case, by injecting the carbonaceous material powder from 33a, through-breaking and reducing of forming slag, it is possible to soothing slag foaming.
[0066]
　Further, if traveling the reduction treatment, Fe is to migrate into the molten iron, increases gradually also the layer thickness of molten iron layer 6.
　The layer thickness of the molten slag layer 5, from the viewpoint of expressing a function as a buffer zone, preferably 100 ~ 600 mm, more preferably 100 ~ 800 mm. If the layer thickness of the molten slag layer 5 has approached the upper limit, by opening the Dekasuguchi 17, to discharge the reduced slag molten slag layer 5. Also, if the interface between the molten iron layer 6 is close to the upper surface of the shallow bottom part 11a, and opens the tap hole 18, to discharge the molten iron in the molten iron layer 6 (e.g., high P hot metal). In this way, the reduced slag from the tapping port 17 of the furnace body 1, the molten iron from the tap hole 18, intermittently discharged and recovered. Thus, the furnace body within 1, a reduction of molten slag 4 can continue without interruption.
[0067]
　Moreover, the furnace body 1 in operation (i.e., during the reduction process), the by reduction of oxides of molten slag 4 by using the C of carbonaceous material, CO and H 2 hot exhaust gas and the like is generated to. For example, to reducing iron oxide by reaction of FeO + C → Fe + CO ↑ , CO gas is produced. The exhaust gas flows into the slag holding furnace 2 through slag inlet 14 of the furnace body 1 is discharged to the outside of the slag holding furnace 2 as an exhaust passage. The furnace body 1 and sealed, by a slag holding furnace 2 and the exhaust passage, the atmosphere in the furnace body 1, and the CO gas generated by the reduction reaction, H resulting from carbonaceous material (reducing agent) 2 and composed mainly of It is maintained in a reducing atmosphere. Therefore, it is possible to prevent the oxidation reaction on the surface of the molten slag layer 5.
[0068]
[6. Second Embodiment
　will be described with reference to FIGS. 5 and 6, a second embodiment of the present invention. The second embodiment is only the first embodiment and the shape of the furnace body 1 than the above-mentioned different, other functions and configuration, since the first embodiment and substantially the same, detailed description thereof will be omitted.
[0069]
　As shown in FIGS. 5 and 6, in the second embodiment the furnace body 1 does not have a projecting portion 10b. The furnace body 1 has a main body portion 10a of the cross-section of the annular shape.
　Shallow portion 11b is a region having an overlap with slag inlet 14 in a plan view of the main body portion 10a, the furnace bottom 11 is partially raised portion. Shallow portion 11b is formed by, for example, the step 11c of the box-type arranged in contact with the inside of the furnace wall 12. Surface of the step 11c is composed of refractory similar to the inner surface of the other portions of the furnace bottom 11.
[0070]
　The second embodiment is a general furnace shape, even an existing electric furnace without the shallow bottom portion 11b, by attaching the step 11c later, can advantageously be formed a shallow bottom 11b .
[0071]
　FIG as 5 shown in, if the molten slag 4 tilts the opening portion 21 side pouring slag holding furnace 2 is injected into the furnace body 1, molten slag 4 injected from the slag inlet 14, slag below the inlet 14 flows down into the molten slag layer 5. Like the first embodiment, in this section for the shallow bottom portion 11b because there is no molten iron layer 6 below the molten slag layer 5, molten slag 4 immediately after injection and rapidly react with the molten iron layer 6 bumping slag foaming due to the fact that it is possible to prevent the occurrence.
[0072]
　Second embodiment of the present invention described above, as already mentioned, in that it can form a shallow bottom 11b after the existing electric furnace has the advantage in comparison with the first embodiment. On the other hand, since the direction of the first embodiment can take a wide shallow bottom part 11a, the injected molten slag 4 and portions where the molten slag layer 5 is disturbed, molten iron layer in the lower layer of the molten slag layer 5 can 6 to increase the distance between the present portion, it is possible to enhance the effect of preventing the slag foaming. In the second embodiment, the position of the shallow bottom portion 11b becomes close to the center of the furnace body 1 in comparison with the first embodiment. In the center of the furnace body 1, since a large heat by arc discharge between the upper electrode 15 and the furnace bottom electrode 16 occurs, erosion of refractories constituting the surface of the shallow bottom portion 11b, a furnace other parts bottom 11 and, may become larger than the shallow bottom part 11a in the first embodiment.
[0073]
　Thus, the first and the embodiment and the second embodiment of the present invention, since it has different advantages to each, for example, can be carried out by appropriately selected depending on, for example, the current operating conditions and equipment. Further, not limited to these embodiments, the description of these embodiments, it is also possible to employ other embodiments apparent to those skilled in the art.
Example
[0074]
　Next, a description will be given of an embodiment of the present invention. The following examples are merely example of conditions adopted for confirming the workability and effects of the present invention, but the present invention is not limited to the condition of the following examples.
[0075]
　(Simulation)
　First, in order to ascertain the influence of the presence of shallow bottom part 11a prior to the actual operation was carried out computer simulations assuming an electric furnace 100 shown in FIG. The specific procedure is as follows.
　Using a general-purpose fluid analysis software FLUENT First, by injecting molten slag 4 in an electric furnace of the following conditions to observe its behavior from the axial sectional direction of the furnace.
　Furnace volume: 13.8 m 3
　reactor bottom area (S 1 + S 2 ): 7.5 m 2
　furnace slag viscosity: 0.25 Pa · s
　injection Slag Viscosity: 1.0 Pa · s
　Molten viscosity: 0.006 Pa · s
　Shallow the height of the bottom (H): 250 mm
　area of the shallow bottom portion (S 2 ): 1.1 m 2
　or hot water: 1.4 m 3
　injection slug flow width: 500 mm
　slag infusion rate: 1t / min, 5t / min , 10t / min, 20t / min
[0076]
　The results are shown in Figure 7. Example A the example slag injection rate is shallow bottom part 11a in 10t / min 7, Examples Comparative Example A slag infusion rate no shallow bottom part 11a in 1t / min, Example B is slag infusion rate 5t example no shallow bottom part 11a in / min, Comparative example C shows an example slag infusion rate example no shallow bottom part 11a in 10t / min, Comparative example D slug injection rate is no shallow bottom part 11a in 20t / min.
　As shown in FIG. 7, if the slag infusion rate of 1t / min, shallow bottom 11a even without Comparative Example A, was injected molten slag 4 does not reach most of the molten iron layer 6, the injected molten slag the reaction of the 4 and the molten iron layer 6 was not only slightly observed.
　Slag infusion rate is 5t / min, in the case of 10t / min, 20t / min, molten slag 4 injected when there is no shallow bottom 11a reaches the molten iron layer 6, partially plunged into molten iron layer 6 as to react with C in the molten iron is foreseen. In particular 10t / min, 20t / min, the reaction is violent, it was found that splashing and mixing the molten iron and molten slag 4.
　On the other hand, if there is shallow bottom 11a, slug injection rate even 10t / min, injected molten slag 4 is hardly react with molten iron layer 6, thus the molten iron and the mixture of molten slag 4 splashing also It was considered to be no.
　From this result, by providing the shallow bottom portion 11a, which is injected molten slag 4 is mixed with molten iron layer 6 it was found to be prevented from being violently react.
[0077]
(Slag injection Test: Comparative Example)
　Next, in an electric furnace 100 shown in FIG. 2 performs a slug injection test using a shallow bottom 11a is no structure to measure the CO gas generation amount. The specific procedure is as follows.
　First, preformed molten iron layer 6 and the molten slag layer 5 in the furnace body 1. Conditions of the furnace body 1, except that there is no shallow bottom 11a is the same as the simulation.
[0078]
　Then, the power 2.4 mW (240V, 10 kA) the furnace body 1 by supplying on which is continuously running, while introducing carbonaceous material powder at 2.5 kg / min, and injecting molten slag 4 680 kg at a time. As a result, the flow rate 300Nm immediately after injection of the molten slag 4 3 to / h or more CO gas is generated, then gradually flow rate is decreased.
　Then, input of carbonaceous material powder continues to operate without changing, was injected first molten slag 4 from the feeding after about 20 minutes of molten slag 4 540 kg at a time. As a result, the flow rate 400Nm immediately after injection of the molten slag 4 3 to / h or more CO gas is generated, then gradually flow rate is decreased.
　Further, input of carbonaceous material powder continues to operate without changing were injected molten slag 4 from the input of the nearest molten slag 4 after about 15 minutes 800kg at a time. As a result, the flow rate 500Nm immediately after injection of the molten slag 4 3 to / h or more CO gas is generated, then gradually flow rate is decreased.
　Thereafter, to increase the input of carbonaceous material powder 3.5 kg / min, the molten slag 4 was injected 20kg at a time about 25 minutes after the introduction of the most recent molten slag 4. As a result, the flow rate 250Nm immediately after injection of the molten slag 4 3 to / h or more CO gas is generated, then gradually flow rate is decreased.
　Figure 8 shows the above results.
　As shown in FIG. 8, in the electric furnace 100 is not shallow bottom 11a is CO gas is generated immediately after the injection of the molten slag 4, possibility of slag foaming has occurred has been suggested.
[0079]
(Slag injection Test: Example)
　Next, in an electric furnace 100 shown in FIG. 2 performs a slug injection test using a structure in which there is a shallow bottom 11a, to measure the CO gas generation amount. The specific procedure is as follows.
　The furnace body 1 to the power 2.4 mW (240V, 10 kA) was supplied on which is continuously running, without introducing carbonaceous material powder was injected molten slag 4 780 kg at a time. Other conditions: the same as "slug injection Test Comparative Example". As a result, immediately after the injection of the molten slag 4 does not occur CO gas, 100 Nm in the subsequent CO gas generation amount flow 3 was / h or less.
　9 shows the results.
　As shown in FIG. 9, in an electric furnace 100 in which there is a shallow portion 11a, CO gas is not generated immediately after the injection of the molten slag 4, shallow bottom 11a is believed to suppress the occurrence of slag foaming.
[0080]
(Real operation test)
　Next, with and without the shallow bottom part, and operating the electric furnace operation pattern shown in FIG. 10, to confirm the presence or absence of slag foaming.
　First, it was prepared an electric furnace 100 of the following conditions.
　Furnace volume: 13.8 m 3
　reactor bottom area (S 1 + S 2 ): 7.5 m 2
　slag composition: (T.Fe) 0.8%, (CaO) 33.1%, (SiO 2 ) 28.4 %
　molten iron composition: [C] 2.8%, [ Si] 0.18%, [P] 0.33%
　shallow bottom part of the height (H): 250 mm
　area of the shallow bottom portion (S 2 ): 1.1 m 2
　seed amount of hot water: 1.3M 3
[0081]
　Next, as shown in FIG. 10, first, the slag holding furnace 2 slag pot 3, at a frequency of approximately once every 40 minutes, was charged molten slag 4 of about per charge 25t, slag holding furnace 2 It was temporarily held within. Thereafter, the slag holding furnace 2 is tilted to the injection position from the holding position at a frequency of once 10 minutes, the molten slag 4 of 8.0t ~ 8.5t per, molten slag layer in the furnace body 1 5 It was intermittently injected into.
[0082]
　Further, in the slag reduction treatment in the furnace body 1, while continuously supplying power of 30MW to the upper electrode 15 and the furnace bottom electrode 16, through the reducing material inlet 31a and 33a, supplying carbonaceous material powder 45 kg / min It was fed at a rate. Furthermore, through reduced material inlet 31a, as modifier, a silica sand 67 kg / min, the waste alumina refractory powder was fed at a feed rate of 8 kg / min. Incidentally, after the end of the slag reduction treatment, the time until the next injection of the molten slag 4 of the charge from the slag holding furnace 2 is started (about 10 minutes), to reduce the power supplied, carbonaceous material and modifiers the supply was paused.
[0083]
　In each of the examples and comparative examples, the injection period and except the different point injection amount per one time, work patterns were the same. Injection volume per injection cycle and once, Example 1, Example 4 and Comparative Example 1 (injection period 5 minutes, injection volume 4.0t ~ 4.3t per), Example 2 and Comparative Example 2 (injection period 10 minutes, injection volume 8.0t ~ 8.5t per), and example 3 and Comparative example 3 (injection period 15 minutes per injection volume 12t ~ 13t 1 times) is common respectively.
[0084]
　Further, in each of Examples and Comparative Examples, the component composition of the molten slag 4 discharged from the converter slag pot 3 is as shown in Table 1 below.
[0085]
[Table 1]

[0086]
　In each of the examples and comparative examples, as an index indicating the influence of the reaction conditions and exhaust gas treatment equipment in the furnace body 1, the height of slag foaming which occurs during the injection of the molten slag 4 of the furnace body 1, the furnace body 1 occurrence of CO gas (CO + CO in the flow rate and the exhaust gas of the exhaust gas passing through the gas discharge port 25 in 2 was measured determined from concentration).
　A summary of the results is shown in Table 2.
[0087]
[Table 2]

[0088]
　In any of Comparative Examples 1 to 3 also, in the shallow portion 11a is not an electric furnace, injected period becomes longer, as the injection amount per one time increases, the forming and the height is increased, often per injection volume once in Comparative example 3, slag foaming height reached above 2500 mm.
　Further, in any of Comparative Examples 1-3 were also CO gas is rapidly generated in the furnace body 1.
[0089]
　Result is that molten slag 4 immediately after injection in contact with the molten iron layer 6 on the lower layer of the molten slag layer 5, the FeO contained in the molten slag 4 was rapidly react with C contained in the molten iron in the molten iron layer 6, It is considered to be due to forming has occurred.
[0090]
　In contrast, in Examples 1-2, both, as compared with Comparative Examples 1 and 2 under the same conditions, the slag foaming height is significantly reduced, gently generation of CO gas in the furnace body 1 became.
　In Example 3, the slag foaming height is increased temporarily to 600 mm, where yelling blown for 3 minutes at 3 kg / min carbon composite powder from two side walls, and subsided to 300 mm. As a result, most injection period longer, even once per injection volume is large Example 3, it was possible to suppress the slag foaming height 300 mm.
　Thus, the furnace body 1 according to the first embodiment of the present invention, by providing the shallow bottom portion 11a, while suppressing the generation of slag foaming, to increase the slug injection amount per one time than conventional it can be said that has become possible.
[0091]
　On the other hand, also in Example 4 using the furnace body 1 according to the second embodiment, the slag foaming height (160 mm) is, in Example was used a furnace body 1 of the first embodiment 1 (90 mm) although slightly higher than, it is greatly reduced as compared to Comparative example 1 under the same conditions (1200 mm). As a result, CO gas evolution was moderate. Therefore, even the furnace body 1 according to the second embodiment, by providing the shallow bottom portion 11b, it has been demonstrated that the effect of suppressing slag foaming is sufficiently obtained.
[0092]
　However, as a result of repeated operations for Examples 1-4 In Examples 1-3, by the refractory surface of the shallow bottom portion 11a is 50mm melting, whereas it was possible to operate the 700-1000 Charge in operation of example 4, 200-300 charge, refractory surface of the shallow bottom portion 11b is 50mm erosion. Therefore, it can be said that the durability of the surface of the furnace bottom 11, also demonstrated that the direction of the furnace body 1 according to the first embodiment is advantageous. Incidentally, it is the furnace body 1 according to the second embodiment has other advantages are as described above.
[0093]
　Having described in detail preferred embodiments of the present invention with reference to the accompanying drawings, the present invention is not limited to such an example. It would be appreciated by those skilled in the relevant field of technology of the present invention, within the scope of the technical idea described in the claims, it is intended to cover various changes and modifications , also such modifications are intended to fall within the technical scope of the present invention.
Industrial Applicability
[0094]
　According to the present invention, it is possible to provide an electric furnace can be prevented and the molten iron layer of molten slag and electric furnace immediately after being injected from the slag holding furnace is vigorously mixed to produce a large slag foaming.
DESCRIPTION OF SYMBOLS
[0095]
1: furnace
2: Slag holding furnace
3: Slag pot
4: molten slag
5: molten slag layer
6: molten iron layer
10a: body portion
10b: projecting portion
11: the furnace bottom
11a: shallow bottom
11b: shallow bottom
11c: Step
11d: deep portion
12: furnace wall
13: furnace roof
14: slag inlet
15: upper electrode
16: furnace bottom electrode
17: Dekasuguchi
18: outflow
20: furnace body
21: spout unit
25: gas discharge port
26 : slag inlet
27: holding furnace lid
28: slug injection path
29: spout
31: raw material supply unit
31a: reduction material inlet
33a: reduction material charging port
32: raw material supply unit
33: raw material supply unit
40: tilting device
44 : tilting axis
100: electric furnace

The scope of the claims
[Requested item 1]
　A furnace body having an electrode,
　and a slag holding furnace capable injected into the furnace body the molten slag by tilting holds the molten slag molten state
　by an electric furnace having,
　the furnace body is
　cylindrical and the furnace wall,
　the furnace lid provided at the upper end of the furnace wall,
　provided at a lower end of the furnace wall, and a deep bottom portion, the height relative to the deepest portion of the deep bottom 150mm or more, in the following areas 500mm a shallow bottom, a furnace bottom with,
　provided in the furnace lid, and slag inlet where the molten slag is poured from the slag holding furnace
　has,
　the slag inlet at the shallow portion in plan view have overlapping,
　characterized in that the area ratio in plan view of the shallow bottom portion to the furnace bottom 5% or more, 40% or less, an electric furnace.
[Requested item 2]
　The furnace wall,
　a body of annular shape is the cross-sectional shape perpendicular to the height direction,
　has a protruding portion that protrudes in the radial direction of the body,
　the shallow bottom portion provided at a lower end of said projecting portion, the slag inlet is characterized in that it is provided on an upper end of the protruding portion, an electric furnace according to claim 1.
[Requested item 3]
　The furnace walls, the cross-sectional shape perpendicular to the height direction has a body of annular shape,
　the shallow bottom portion is provided at a lower end of said body, an electric furnace according to claim 1.
[Requested item 4]
　Provided on both of the furnace lid or the furnace lid and the furnace wall, characterized in that it has a reducing material inlet for introducing reducing agent into the furnace, either of claims 1 to 3 1 electric furnace according to the item.