JP2015189991A - Desiliconization and desulfurization method in hot metal ladle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct a desiliconization and desulfurization treatment efficiently, discharge slag from a hot metal ladle efficiently by consecutively treating the hot metal ladle with gradient and improve productivity.SOLUTION: An inclination angle of a hot metal ladle θ is 3.0≤θ≤9.0, an injection amount of iron oxide containing Fe=50 to 80 mass% is 1.0 to 22.2 kg/t, height of an oxygen lance is 0.65 to 1.50 m, a gaseous oxygen flow is 0.15 to 0.30 Nm/min t, and a discharge angle α is 0≤α≤θ+20, a submergence depth is 1.5 to 2.0 m and a nitrogen gas flow is 0.0056 to 0.020 Nm/min t for an injection lance. For the injection lance, the discharge angle α is 0≤α≤θ+20, the submergence depth is 1.5 to 2.0 m and the nitrogen gas flow is 0.0056 to 0.020 Nm/min t and a blowing speed of Mg weight is 0.030 to 0.165 kg/min t.

Description

  The present invention relates to a desiliconization and desulfurization method in a hot metal ladle that performs desiliconization and desulfurization using a hot metal ladle as a refining vessel in the hot metal pretreatment, for example.

Conventionally, as what performs desiliconization processing and desulfurization processing of hot metal using a hot metal ladle (ladder) etc., there are some which are shown in patent documents 1-3, for example.
Patent Document 1 is intended to perform refining without removing slag at the time of switching from desiliconization treatment to desulfurization treatment when performing desiliconization desulfurization of hot metal in a container using an injection lance and an oxygen lance. is there. In this Patent Document 1, a hot metal containing 0.25% or more of Si is charged into a ladle, oxygen is blown from the oxygen lance to the hot metal in the ladle, and a stirring gas and an oxygen lance in the direction from the injection lance are used. This is a hot metal refining method in which hot metal desiliconization and desulfurization are performed by blowing a refining agent. The refining agent is changed from a desiliconization material to a desulfurization agent, and the slag composition when changing from desiliconization to desulfurization is C / S = 0.5-1.0, T.I. Adjustment is made so that Fe ≦ 15%.

Patent Document 2 aims to continuously perform desiliconization and desulfurization of hot metal without using fluorite (CaF ₂ ) and without performing intermediate denitrification. In this Patent Document 2, while stirring hot metal in a processing vessel, manganese-containing minerals and quicklime are added to desiliconize the hot metal and increase the Mn content, and then a solidifying agent is added to solidify the slag. After that, the desulfurizing agent is added without intermediate defoaming, and the hot metal desulfurization treatment is subsequently performed.
Patent Document 3 aims to sufficiently improve the desiliconization / phosphorus removal rate at a low cost, and further to easily solve the problem of the poor inlet of the molten metal. In Patent Document 3, in the hot metal preliminary treatment method in which an oxidizing agent is blown through a lance immersed in hot metal in a processing container, first and second total two are used as lances, and the immersion depth of the first lance is used. The oxygen supply rate per lance is set to 0.05 Nm ³ / min / molten metal t or more, and is synchronized with at least a part of the oxidizing agent blowing period. Tilting.

JP 2013-155401 A JP 2005-146359 A JP 2004-018942 A

Patent Document 1 is a technique for performing desiliconization and desulfurization of hot metal using an injection lance and an oxygen lance. However, the tilt angle of the hot metal ladle and the injection lance for improving the desiliconization oxygen efficiency and desulfurization lime efficiency are further disclosed. The discharge direction is not disclosed, and desiliconization and desulfurization may not be performed sufficiently.
Although Patent Document 2 indicates that desiliconization and desulfurization are performed without performing intermediate degassing, conditions for performing desiliconization and desulfurization are not sufficiently shown, and intermediate denitrification is performed. In fact, desiliconization and desulfurization cannot be performed sufficiently.

Patent Document 3 discloses that the hot metal ladle is tilted when performing desiliconization and dephosphorization, but the tilting conditions are not sufficiently shown, and the injection lance and other conditions are sufficient. The fact is that at least desiliconization cannot be performed sufficiently.
Therefore, in the present invention, desiliconization and desulfurization treatment can be performed efficiently, and by continuously treating the hot metal lath with tilting, slag can be efficiently discharged from the hot metal ladle and productivity is also improved. It is an object of the present invention to provide a method for desiliconization and desulfurization in a hot metal ladle that can be made.

In order to achieve the above object, the present invention has taken the following measures.
The technical means of the present invention is a method of performing desiliconization and desulfurization using a hot metal ladle as a refining vessel in the hot metal pretreatment, wherein the inclination angle θ (°) of the hot metal ladle relative to the lance inserted in the hot metal ladle In carrying out the desiliconization treatment by inclining in the range of (1), T. is introduced from the charging device installed at the top of the hot metal ladle at the start of the desiliconization treatment. Iron oxide containing Fe = 50-80% by mass is charged in an amount of 1.0-22.2 kg / t, and the height of the oxygen lance disposed on the center side of the hot metal ladle is 0.65-1.50 m, Oxygen gas was blown at an oxygen gas flow rate of the oxygen lance of 0.15 to 0.30 Nm ³ / min · t, and an injection lance disposed on the side of the oxygen lance was immersed in the hot metal, so that the injection lance Is set to an angle satisfying the expression (2), the immersion depth of the injection lance is set to 1.5 to 2.0 m, and the nitrogen gas flow rate of the injection lance is set to 0.0056 to 0.020 Nm ³ / As min · t, the desiliconization treatment is performed by blowing CaO or a mixed powder of CaO and iron oxide together with the nitrogen gas to perform the desulfurization treatment. Thus, while maintaining the discharge angle α (°) of the injection lance at an angle satisfying the expression (2), the immersion depth of the injection lance is 1.5 to 2.0 m, and the nitrogen gas flow rate of the injection lance 0.0056 to 0.020 Nm ³ / min · t, and a mixture powder of CaO and Mg together with the nitrogen gas is blown at a Mg weight rate of 0.030 to 0.165 kg / min · t, so that the desulfurization is performed. The hot metal ladle is inclined after the desulfurization treatment, and the slag is discharged with a slag dragger.

3.0 ≦ θ ≦ 9.0 (1)
0 ≦ α ≦ θ + 20 (2)

  According to the present invention, desiliconization and desulfurization treatment can be performed efficiently, and the hot metal ladle is inclined and continuously treated, whereby slag can be efficiently discharged from the hot metal pan and productivity is improved. be able to.

It is the whole scouring equipment schematic. It is a figure which shows the state which discharges slag. It is a figure which shows the relationship between desiliconization oxygen efficiency and slag generation basic unit. It is a figure which shows the relationship between desulfurization lime efficiency and slag generation basic unit. It is a figure which shows the relationship between the total processing time in a desiliconization and a desulfurization process, and a pan desiliconization desulfurization application ratio.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The desiliconization and desulfurization method in the hot metal ladle according to the present invention is a method in which hot metal produced in a blast furnace or the like is charged into a hot metal ladle and subjected to desiliconization or desulfurization of the hot metal. In other words, the present invention is intended for desiliconization and desulfurization performed in a hot metal pretreatment process performed before hot metal dephosphorization.

FIG. 1 shows a scouring treatment facility capable of desiliconization and desulfurization.
First, a scouring treatment facility will be described.
The scouring treatment equipment 1 includes a hot metal ladle 2 installed, a tilting device 3 for tilting the hot metal ladle 2 installed, a dust collector 4 for collecting dust such as exhaust gas, and an iron oxide from the top to the hot metal ladle 2 installed. A charging device 5 for charging a source or the like, an oxygen lance 6 for blowing oxygen, and an injection lance 7 for blowing a scouring material or the like are provided.

The hot metal ladle 2 is a scouring container with a refractory lined inside, and is a container that also has a charging container capable of charging hot metal into the furnace body, that is, a ladle.
The tilting device 3 is a device for tilting the hot metal ladle 2 with respect to the lance (oxygen lance 6, injection lance 7). For example, a hydraulic cylinder) 11 is provided. In the tilting device 3, a shackle (engaged portion) 12 is provided on the cart 10 or the hot metal ladle 2, and a hook (engaging portion) 13 provided at the tip of the hydraulic cylinder 11 is engaged with the shackle 12. By extending and contracting the hydraulic cylinder 11, the hot metal ladle 2 on the carriage 10 can be tilted. The tilting device 3 is not limited to the example described above.

The charging device 5 is, for example, a device that is configured by a storage hopper, a belt conveyor, or the like, and that supplies a cut iron oxide source or the like from the top toward the hot metal ladle 2. In addition, the charging amount thrown into the hot metal ladle 2 by the charging device 5 can be set arbitrarily.
The oxygen lance 6 is formed in a pipe shape and has 2 to 6 nozzle holes formed on the lower end side, and is an apparatus that can spray an oxygen jet onto the hot metal surface supplied from above. The oxygen lance 6 is installed at the center in the width direction of the hot metal ladle 2 when the hot metal ladle 2 is horizontal. The number of nozzle holes in the oxygen lance is a general number.
The injection lance 7 is generally a cylindrical structure constructed of an irregular refractory material (castable or the like), and is embedded around a pipe-shaped core metal capable of blowing powder inside. The injection lance 7 is disposed on the side of the oxygen lance 6 on the side opposite to the side on which the hot metal ladle 2 is tilted. Hereinafter, for convenience of explanation, when the hot metal ladle 2 is tilted, the side on which the edge of the hot metal ladle 2 is lowered is referred to as “tilting side”, and the side opposite to the tilting side is sometimes referred to as “non-tilting side”. .

In such a scouring treatment facility 1, the hot metal ladle 2 is tilted by the tilting device 3, oxygen gas is blown from the oxygen lance 6, a scouring material is supplied from the injection lance 7, and the iron oxide is further fed from the charging device 5. By supplying a source or the like, desiliconization treatment or desulfurization treatment can be performed.
Hereinafter, the desiliconization and desulfurization methods in the hot metal ladle are described in detail.

When performing desiliconization and desulfurization, first, a hot metal ladle charged with hot metal is installed on a cart. After installing the hot metal ladle on the carriage, the hot metal ladle is tilted to a predetermined angle by a tilting device. Specifically, the desiliconization treatment is performed by inclining the inclination angle θ (°) of the hot metal ladle within the range of the formula (1).
3.0 ≦ θ ≦ 9.0 (1)
Here, the inclination angle θ of the hot metal ladle is 0 ° when the hot metal ladle is placed horizontally (the upper end of the hot ladle is horizontal with respect to the floor surface, etc.), and the hot metal relative to the horizontal line L1. It is the angle formed by the top of the pan. For example, when the tilt angle θ (°) is tilted by engaging the hook 13 with the shackle 12 and expanding and contracting the hydraulic cylinder 11, the stroke of the hydraulic cylinder 11 contracting, that is, the rising stroke of the hook 13, and the hot metal ladle It is possible to obtain geometrically according to the dimensions.

  When the desiliconization process is performed while maintaining the tilt angle θ of the hot metal ladle at 3.0 ° or more, the desiliconization slag generated in the desiliconization process flows in the inclined direction, and the slag starts from the upper end of the hot metal ladle. It can flow out (discharge) to the pit 15. On the other hand, when the inclination angle θ of the hot metal ladle is less than 3.0, since the inclination angle θ of the hot metal ladle is too small, the desiliconized slag does not flow out of the hot metal ladle. As a result, the desiliconized slag stayed in the hot metal ladle, that is, the cover slag obstructs the scouring material and the like supplied from above. For example, the cover slag obstructs the iron oxide source (iron source) supplied from the charging device, or obstructs the gaseous oxygen sprayed from the oxygen lance 6 or the like toward the hot metal, thereby reducing the desiliconization oxygen efficiency. .

  Furthermore, when the inclination angle θ of the hot metal ladle is less than 3.0 °, the desulfurization reaction efficiency decreases due to the influence of oxidized desiliconization slag when the desulfurization process is continuously performed after the desiliconization process. Specifically, the desiliconized slag that remains oxidized without being discharged is considered to have a high iron oxide (FeO) concentration, that is, a slag having a high oxygen potential. Therefore, when MgS generated after the transition reaction with metallic Mg reaches the slag interface, the reaction of “MgS + FeO = MgO + Fe + S” proceeds under an atmosphere with a high oxygen potential, and the desulfurization reaction due to the dissociation or oxidation of MgS proceeds. The desulfurization efficiency will be reduced. For example, “Iron and Steel” Vol. 92 (2006) No. 2, "Resulfurization rate in Mg hot metal desulfurization process". Moreover, when the inclination angle θ of the hot metal ladle is less than 3.0 °, the removal time after the treatment becomes longer and extended, so that the efficiency of the desiliconization treatment is lowered.

On the other hand, when the tilt angle θ of the hot metal ladle exceeds 9.0 °, the desiliconization slag generated in the desiliconization process flows out of the hot metal pan, but the tilt angle θ is too large, so that it is blown from the injection lance 7. Since the area of the hot metal stirred by the gas or the like is relatively small, the desiliconization oxygen efficiency is lowered. That is, when the inclination angle θ of the hot metal ladle is increased, the hot metal in the region on the non-tilting side of the injection lance 7 becomes difficult to be stirred by gas or the like, and the desiliconization oxygen efficiency is lowered.

  Furthermore, when the tilt angle θ of the hot metal ladle exceeds 9.0 °, there is a large amount of desiliconized slag that flows out to the outside, and when desulfurizing is performed continuously, a cover suitable for desulfurizing is applied on the hot metal. The slag is not floating. As a result, the powder blown by the injection lance 7 does not stay at the slag metal interface and immediately blows up to the upper part of the cover slag, so that the desulfurization reaction efficiency is lowered. For this reason, the desiliconization process is performed by inclining the inclination angle θ (°) of the hot metal ladle in the range of the formula (1).

In addition, in the injection lance 7, as the scouring material in the desiliconization process, that is, as the desiliconization material, powder containing CaO (quick lime, calcined lime) or mixed powder containing CaO (quick lime, calcined lime) and iron oxide. I am going to infuse. When using mixed powder, what mixed mill scale etc. in a predetermined ratio beforehand as an iron oxide source is used.
In the desiliconization process, the T.D. Iron oxide containing Fe = 50-80% by mass is charged at 1.0-22.2 kg / t. Here, the iron oxide used in the desiliconization treatment is a powder obtained by sizing and drying a mill scale or the like generally generated in an iron mill, or a sintered ore pellet powder. In addition, iron ore lump or powder may be used as iron oxide.

  T. of iron oxide When Fe is less than 50%, impurities input as components other than iron may be generated as desiliconized slag, and the cover slag after charging may increase. If the cover slag increases, the desiliconization reaction between the scouring material blown from the injection lance 7 and the gaseous oxygen blown to the hot metal by the oxygen lance is hindered, resulting in a decrease in desiliconization oxygen efficiency. There is a risk of being invited. On the other hand, T.O. When Fe is larger than 80%, most of the input is made as an iron source, and the amount of solid oxygen to be contributed as a desiliconization reaction is insufficient. As a result, the desiliconization oxygen efficiency may be lowered. is there.

  Further, when the iron oxide to be input is larger than 22.2 kg / t, the iron oxide is T.D. As in the case where Fe is less than 50%, impurities input as components other than iron may be generated as desiliconized slag, and the cover slag after charging may increase. As a result, there is a possibility that the cover slag inhibits the desiliconization reaction between the scouring material and the gaseous oxygen sprayed on the molten iron, leading to a decrease in desiliconization oxygen efficiency. On the other hand, when the iron oxide to be input is less than 1.0 kg / t, the input amount of solid oxygen to be input for the desiliconization treatment is insufficient, and there is a possibility that the desiliconization oxygen efficiency is lowered.

In the desiliconization process, the height of the oxygen lance is set to 0.65 to 1.50 m, and the oxygen gas flow rate of the oxygen lance is set to 0.15 to 0.30 Nm ³ / min · t to blow oxygen gas. Yes. The height of the oxygen lance is the height from the molten metal surface to the tip (lower end) of the oxygen lance. The height of the oxygen lance is measured before the desiliconization process, that is, before the oxygen gas is blown with the oxygen lance, for example, by measuring the molten metal level with a microwave level meter and the position of the lower end of the oxygen lance. Is measured mechanically. The difference between the measured hot water level and the position of the lower end of the oxygen lance is defined as the height of the oxygen lance.

  When the oxygen lance height is less than 0.65 m, the hot metal rebounds greatly by the jet jet of gaseous oxygen blown by the oxygen lance, and the hot metal that has come out on the surface by the stirring flow reacts with gaseous oxygen (oxygen gas) Since it scatters before, there exists a possibility that desiliconization oxygen efficiency may fall as a result. Also, the hot metal bounced off by the jet jet of gaseous oxygen tends to adhere directly to the oxygen lance, which may cause a problem that the oxygen lance is damaged. On the other hand, when the oxygen lance height is higher than 1.50 m, the jet jet of gaseous oxygen blown by the oxygen lance may not penetrate the upper desiliconization slag (cover slag) and may not reach the hot metal surface of the hot metal. . As a result, the amount of gaseous oxygen supplied does not contribute as a desiliconization reaction, and as a result, the desiliconization oxygen efficiency may be reduced.

The oxygen gas flow rate of the oxygen lance is 0.15 to 0.30 Nm ³ / min · t and the oxygen gas is blown. When the oxygen gas flow rate is less than 0.15 Nm ³ / min · t, the jet jet of gaseous oxygen may not penetrate the desiliconization slag (cover slag) and may not reach the molten metal surface. As a result, the amount of gaseous oxygen supplied does not contribute as a desiliconization reaction, and as a result, the desiliconization oxygen efficiency may be reduced. On the other hand, when the oxygen gas flow rate is larger than 0.30 Nm ³ / min · t, the hot metal rebounds greatly due to the jet jet of gaseous oxygen, and the hot metal that has come out on the surface by the stirring flow reacts with gaseous oxygen (oxygen gas). As a result, the desiliconization oxygen efficiency may be reduced. Also, the hot metal bounced off by the jet jet of gaseous oxygen tends to adhere directly to the oxygen lance, which may cause a problem that the oxygen lance is damaged.

Further, in the desiliconization process, the discharge angle α (°) of the immersed injection lance 7 is set to an angle satisfying the expression (2).
0 ≦ α ≦ θ + 20 (2)
The discharge angle α of the injection lance 7 is defined by defining the X-axis as the axis perpendicular to the injection lance 7 (horizontal direction), and the axis of the discharge port 16 of the injection lance 7. It is a horn. Here, the discharge angle α can be changed by changing the angle of the pipe provided inside the injection lance 7 (the angle of the discharge port 16). In addition, by preparing several types of injection lances 7 with different discharge angles α, that is, with different pipe angles, and blowing each of the injection lances 7, reaction efficiency in desiliconization and desulfurization treatment with respect to the angle. Can be verified.

  When the discharge angle α is smaller than 0 (minus), the powder is blown upward from the horizontal direction. Naturally, the contact time between the powder and the hot metal by the injection lance 7 is shortened, so that the desiliconization oxygen efficiency is lowered. I will invite you. On the other hand, when the discharge angle α is larger than θ + 20 °, the amount of contact of the powder with the bottom of the hot metal ladle increases when the powder is blown. As a result, the powder easily adheres to the bottom of the hot metal ladle and does not react with the hot metal, and the supplied powder is lost with respect to the input, resulting in a decrease in desiliconization oxygen efficiency.

  In the silicon removal treatment, the immersion depth of the injection lance 7 is 1.5 to 2.0 m. Generally, in order to ensure stirring of hot metal in the hot metal ladle, the immersion depth is specified. The immersion depth is a depth at which the injection lance 7 is immersed in the hot metal, and is a vertical distance from the hot metal bath surface (water surface) to the discharge port 16 of the injection lance 7. In order to enhance the reaction between the hot metal and the desiliconized material (powder), it is preferable that the immersion depth is deep, but it is desirable not to contact the bottom of the hot metal pan due to equipment restrictions.

  When the immersion depth is less than 1.5 m, the contact time between the powder blown by the injection lance 7 and the hot metal is shortened, and the desiliconization oxygen efficiency may be reduced. On the other hand, when the immersion depth is larger than 2.0 m, the amount of contact of the powder with the bottom of the hot metal pan increases when the powder is blown. As a result, the powder easily adheres to the bottom of the hot metal ladle and does not react with the hot metal and loses the input of the supplied powder, resulting in a decrease in desiliconization oxygen efficiency.

  In the silicon removal treatment, nitrogen gas is used as an inert carrier gas for carrying the silicon removal material. As the inert gas, there is argon gas, but nitrogen gas is adopted from the viewpoint of being inexpensive and economical. In this embodiment, nitrogen gas is blown together with powder containing CaO (quick lime, calcined lime) or mixed powder containing CaO (quick lime, calcined lime) and iron oxide.

Now, when blowing nitrogen gas, the optimum flow rate should ensure sufficient stirring power without clogging the powder in the injection lance 7 by optimizing the flow rate of nitrogen gas (flow rate of blowing nitrogen gas). It is necessary to. Specifically, in the desiliconization process, the nitrogen gas flow rate of the injection lance 7 is set to 0.0056 to 0.020 Nm ³ / min · t.

When the nitrogen gas flow rate is less than 0.0056 Nm ³ / min · t, the powder is clogged and blocked in the injection lance 7, so that stirring cannot be performed and the desiliconization oxygen efficiency is lowered. On the other hand, when the nitrogen gas flow rate is larger than 0.020 Nm ³ / min · t, the stirring by blowing the nitrogen gas through the injection lance 7 is large, and the rising height of the hot metal to the molten metal surface is increased, and the stirring flow causes the surface to come to the surface. Since the hot metal thus scattered is scattered before reacting with gaseous oxygen, the desiliconization oxygen efficiency is lowered as a result.

In summary, according to the present invention, the tilt angle θ (°) of the hot metal ladle is tilted within the range of the formula (1), and at the start of the desiliconization process, the T.S. Iron oxide containing Fe = 50-80% by mass is charged at 1.0-22.2 kg / t. The height of the oxygen lance is set to 0.65 to 1.50 m, and the oxygen gas flow rate of the oxygen lance is set to 0.15 to 0.30 Nm ³ / min · t. Furthermore, the injection direction of the injection lance 7 is set to a range of an angle α (°) satisfying the expression (2) with respect to the horizontal direction, and the immersion depth of the injection lance 7 is set to 1.5 to 2.0 m. The silicon gas flow rate of the lance 7 is set to 0.0056 to 0.020 Nm ³ / min · t, and CaO or a mixed powder of CaO and iron oxide is blown together with the nitrogen gas to perform desiliconization treatment.

Now, after carrying out the desiliconization treatment, the desulfurization treatment is continued as it is.
Specifically, after the desiliconization treatment, the oxygen lance is raised to stop the supply of gaseous oxygen, and the scouring material in the injection lance 7 is switched from the desiliconized material to the desulfurized material. As the desulfurization material, a mixed powder containing CaO (quick lime, calcined lime) and Mg is used. For example, a mixed powder in which quick lime (calcined lime) as a CaO source and metal Mg having a particle size of about 250 μm as a Mg source are mixed in a prescribed ratio is used as a desulfurization material. By mixing metal Mg, a transition reaction is generally caused by reaction between Mg vapor and S in the hot metal in the hot metal, and then a reaction of “MgS + CaO → CaS + MgO” occurs at the slag metal interface, desulfurization. CaS, which is a chemical potential stable compound, is immobilized in the slag, and it becomes possible to prevent sulfation. In order to improve desulfurization lime efficiency, this transition reaction and the fixation of CaS to slag are important. The inert carrier gas is nitrogen gas and is the same as the desiliconization process.

In blowing the desulfurized material, the discharge angle α of the injection lance 7 is maintained at an angle satisfying the expression (2).
When the discharge angle α is smaller than 0 (minus), the powder is blown upward from the horizontal direction. Naturally, the contact time between the powder and the molten iron by the injection lance 7 is shortened, leading to a decrease in desulfurized lime efficiency. I will. On the other hand, when the discharge angle α is larger than θ + 20 °, the amount of contact of the powder with the bottom of the hot metal ladle increases when the powder is blown. As a result, the powder easily adheres to the bottom of the hot metal ladle and does not react with the hot metal, and the supplied powder is lost to the input, resulting in a decrease in desulfurized lime efficiency.

  Also in the desulfurization treatment, the immersion depth of the injection lance 7 is 1.5 to 2.0 m. When the immersion depth is less than 1.5 m, the contact time between the powder blown by the injection lance 7 and the hot metal is shortened, and the desulfurization lime efficiency may be reduced. On the other hand, when the immersion depth is larger than 2.0 m, the amount of contact of the powder with the bottom of the hot metal pan increases when the powder is blown. As a result, the powder tends to adhere to the bottom of the hot metal ladle and does not react with the hot metal, resulting in a loss with respect to the input of the supplied powder, resulting in a decrease in desulfurized lime efficiency.

Also in the desulfurization treatment, the nitrogen gas flow rate of the injection lance 7 is set to 0.0056 to 0.020 Nm ³ / min · t. When the nitrogen gas flow rate is less than 0.0056 Nm ³ / min · t, the powder is clogged and blocked in the injection lance 7, so that stirring cannot be performed and desulfurization lime efficiency is lowered. On the other hand, when the flow rate of nitrogen gas is larger than 0.020 Nm ³ / min · t, the blowing speed in the injection increases, so the contact time between the desulfurizing agent discharged from the injection and the hot metal becomes short, and in the hot metal The transition reaction due to the reaction between the Mg vapor and the hot metal S is not promoted and the efficiency of desulfurized lime is reduced.

Further, in the desulfurization treatment, the mixed powder of CaO and Mg is blown at a rate of Mg weight of 0.030 to 0.165 kg / min · t. When the rate of the weight of Mg to be blown is less than 0.030 kg / min · t, the transition reaction by Mg vapor is not promoted and the desulfurized lime efficiency may be lowered. On the other hand, if the speed of the weight of Mg to be blown is greater than 0.165 kg / min · t, a part of the Mg powder blown by the injection lance 7 does not react with the hot metal and blows directly onto the hot metal pan and collects with the exhaust gas. Dust may result in a decrease in desulfurized lime efficiency.
In summary, according to the present invention, when the desulfurization treatment is performed, the immersion depth of the injection lance 7 is set to 1.5 to 5 while maintaining the discharge angle α of the injection lance 7 at an angle satisfying the expression (2). 2.0 m, the nitrogen gas flow rate of the injection lance 7 is 0.0056 to 0.020 Nm ³ / min · t, and the mixed powder of CaO and Mg together with the nitrogen gas has an Mg weight of 0.030 to 0.165 kg / min. -The desulfurization process is performed by blowing in at the speed of t.

  After the desulfurization treatment, the hot metal ladle is inclined and the slag is discharged by the slag dragger. Specifically, as shown in FIG. 2, after the desulfurization treatment, the slag dragger 14 is positioned on the upper side of the hot metal ladle with the hot metal ladle inclined at a predetermined angle, and the slag dragger 14 desulfurizes slag. Exclusion of In addition, it is desirable that the inclination angle of the hot metal ladle at the time of demetalization is larger than that at the time of desulfurization treatment. Further, the desulfurization slag may be removed using an apparatus other than the slag dragger.

  Tables 1 to 6 show examples of desiliconization and desulfurization methods in the hot metal ladle according to the present invention, and comparative examples in which desiliconization treatment and desulfurization treatment were performed by methods different from the present invention. Is a summary.

Implementation conditions in Examples and Comparative Examples will be described.
As the refining vessel, a hot metal ladle for hot metal was used. The radius of the hot metal pan is 1.34 m. The amount of hot metal during the treatment was 87.5-96.0 tons, and the hot metal temperature was 1290-1400 ° C. The carbon concentration of the hot metal was 4.5 to 4.8 mass%, the Si concentration of the hot metal was 0.40 to 0.90 mass%, and the S concentration of the hot metal was 0.011 to 0.040 mass%.

Regarding the oxygen lance, the number of nozzle holes was 4, the nozzle throat diameter was 18 mm, the nozzle inclination angle was 9 °, and the nozzle outlet diameter (discharge diameter) was 20.20 mm. The height of the oxygen lance was 0.65 to 1.50 m, and the flow rate of oxygen gas (oxygen flow rate) was 0.15 to 0.30 Nm ³ / min · t. The collision pressure of oxygen gas was set in the range of 0.6 to 4.5 kpa. The oxygen amount of 0.2 to 3.5 Nm ³ / t was determined by blowing control according to a conventional method of those skilled in the art depending on the Si concentration before treatment.

Regarding the injection lance 7, the number of nozzle holes was one, the nozzle diameter was 15.88 mm, and the horizontal distance between the oxygen lance and the injection lance 7 was 0.55 m.
In the desiliconization treatment, a powder containing CaO or a mixed powder in which CaO and iron oxide are mixed is used as a powder constituting the desiliconization material. In the mixed powder, the powder ratio was CaO: iron oxide = 50: 50. Moreover, when not using mixed powder as a desiliconization material, it was set as CaO: iron oxide = 100: 0. The blowing amount of the desiliconized material was determined by the auxiliary raw material control in the ordinary manner of those skilled in the art within the range of 0.6 to 4.3 kg / t according to the Si concentration before the treatment.

In the desulfurization treatment, a mixed powder of CaO and metal Mg was used as the powder constituting the desulfurization material. As the powder ratio, two kinds of weight ratios of CaO: metal Mg = 85: 15 and 80:20 were used. The blowing amount of the desulfurization material was determined in the range of 0.9 to 3.5 kg / t in accordance with the S concentration before the treatment by the auxiliary raw material control of those skilled in the art.
In the removal treatment, after the desulfurization treatment, the angle of the hot metal ladle was tilted to 10 to 30 ° according to the situation of the desulfurization slag by the slag dragger, and the removal was carried out by an ordinary operating procedure.
In the examples, even when the desiliconization process was shifted to the desulfurization process, the injection angle α of the injection lance was set to an angle satisfying the expression (2). The injection angle α of the injection lance is desirably maintained at the same angle as the desiliconization process when the desiliconization process is shifted to the desulfurization process.

In the examples and comparative examples, desiliconization oxygen efficiency and desulfurization lime efficiency were evaluated. The desiliconization oxygen efficiency (ηSi) indicates the ratio of the oxygen content used for the oxidation of [Si] in the hot metal with respect to the given amount of oxygen, and can be determined by equation (3).
Moreover, desulfurization lime efficiency ((eta) S) shows the ratio of the lime content used for reaction with [S] in hot metal with respect to the lime content which the desulfurization agent gave, and can be calculated | required by Formula (4). . When reacting with a lime-based desulfurizing agent, the reaction formula is expressed as CaO + Mg + S = CaS + MgO. Therefore, desulfurized lime efficiency (ηS) was adopted as an index indicating whether lime effectively contributed to the desulfurization reaction.

In Examples 1 to 27, the tilt angle θ of the hot metal ladle 2 is tilted so as to satisfy the range of the formula (1). Iron oxide containing Fe = 50-80 mass% is charged at 1.0-22.2 kg / t, the oxygen lance height is 0.65-1.50 m, and the oxygen gas flow rate (oxygen flow rate) is 0.15. ˜0.30 Nm ³ / min · t. Moreover, in an Example, let the discharge angle (alpha) of an injection lance be an angle which satisfy | fills Formula (2), the immersion depth of an injection lance shall be 1.5-2.0 m, and nitrogen gas flow rate (nitrogen flow rate) is 0.0056- 0.020 Nm ³ / min · t.

Further, in the examples, when performing the desulfurization treatment, the immersion depth of the injection lance was set to 1.5 to 2.0 m, the nitrogen gas flow rate was set to 0.0056 to 0.020 Nm ³ / min · t, and CaO and Mg The mixed powder containing was blown at a Mg weight rate of 0.030 to 0.165 kg / min · t. Thus, in the Example, since all the above-mentioned conditions were satisfied, the desiliconization oxygen efficiency in the desiliconization treatment was 40% or more, and the desulfurized lime efficiency was 5% or more. In addition, the desiliconization time was 15 minutes or less and the desulfurization time was 5 minutes or less.

On the other hand, in Comparative Examples 28 to 37, since the inclination angle θ of the hot metal ladle 2 is out of the range of the formula (1), the desiliconization oxygen efficiency is less than 40% and the desulfurized lime efficiency is less than 5%.
Further, in Comparative Examples 38 to 41, the T.I. Fe was less than 50% by mass or more than 80% by mass. In Comparative Examples 42 to 45, the amount of iron oxide input was less than 1.0 kg / t or more than 22.2 kg / t. In Comparative Examples 46 to 49, oxygen lances were used. height exceeds 0.65m below or 1.50m of, in Comparative example 50 to 53, the oxygen gas flow rate exceeds 0.15Nm ³ / min · t less than or 0.30Nm ³ / min · t. Therefore, in Comparative Examples 38 to 53, the desiliconization oxygen efficiency was less than 40%.

In Comparative Examples 54 to 61, since the discharge angle α of the injection lance deviated from the angle satisfying the formula (2), the desiliconization oxygen efficiency exceeded 40% and the desulfurized lime efficiency became less than 5%. In Comparative Examples 62 to 65, since the immersion depth of the injection lance was less than 1.5 m or more than 2.0 m, the desiliconization oxygen efficiency was less than 40%.
In Comparative Examples 66 and 67, since the nitrogen gas flow rate was less than 0.0056 Nm ³ / min · t, nozzle closing occurred and the desiliconization process was interrupted. In Comparative Examples 68 and 69, since the nitrogen gas flow rate exceeded 0.020 Nm ³ / min · t, the desiliconization oxygen efficiency was less than 40%.

In Comparative Examples 70 to 73, in the desulfurization treatment, the immersion depth of the injection lance was less than 1.5 m or more than 2.0 m, so the desulfurized lime efficiency was less than 5%. In Comparative Examples 74 and 75, in the desulfurization treatment, since the nitrogen gas flow rate was less than 0.0056 Nm ³ / min · t, nozzle closing occurred and the desiliconization treatment was interrupted. In Comparative Examples 76 and 77, in the desulfurization treatment, since the nitrogen gas flow rate exceeded 0.020 Nm ³ / min · t, the desulfurized lime efficiency was less than 5%.

  In Comparative Examples 78 and 79, the desulfurized lime efficiency was less than 5% because the Mg weight rate was less than 0.030 kg / min · t when the mixed powder containing CaO and Mg was blown. In Comparative Examples 78 and 79, the desulfurized lime efficiency was less than 5% because the Mg weight rate when the mixed powder containing CaO and Mg was blown exceeded 0.165 kg / min · t. That is, in Comparative Examples 78 and 79, since the amount of CaO blown simultaneously with Mg increased, the efficiency of CaO also decreased and the desulfurized lime efficiency became less than 5%.

  As described above, as shown in the examples, when the desiliconization oxygen efficiency is 40% or more and the desulfurized lime efficiency is 5% or more, the amount of oxygen to be input and the amount of lime can be reduced, and the raw oxygen and solid oxygen can be reduced. Units and lime usage intensity can be reduced. That is, as shown in FIGS. 3 and 4, in the embodiment, the slag generation basic unit can be suppressed and the slag processing cost can be reduced. On the other hand, in the comparative example, the slag generation basic unit increased as compared with the example.

  Further, as shown in the examples, when the desiliconization treatment time is 15 minutes or less and the desulfurization treatment time is 5 minutes or less, the total treatment time can be within 25 minutes. When hot metal is supplied to the hot metal ladle, desiliconization desulfurization treatment can be performed in time for the hot metal supply pitch. That is, as shown in FIG. 5, the pan desiliconization desulfurization application ratio (ratio of the hot metal ladle applied to the desiliconization treatment and desulfurization treatment with respect to the supplied hot metal ladle) can be maintained at 100%.

According to the present invention, by satisfying the above-mentioned conditions, desiliconization and desulfurization treatment can be performed efficiently, and the hot metal ladle is inclined and continuously treated to efficiently discharge slag from the hot metal ladle. And productivity can be improved.
It should be noted that matters not explicitly disclosed in the embodiment disclosed this time, such as operating conditions and operating conditions, various parameters, dimensions, weights, volumes, and the like of a component, deviate from the range normally practiced by those skilled in the art. However, matters that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Scouring processing equipment 2 Hot metal ladle 3 Tilt device 4 Dust collector 5 Input device 6 Oxygen lance 7 Injection lance 10 Cart 11 Expansion mechanism 12 Shackle (engaged part)
13 Hook (engagement part)
14 Slag dragger 15 Slag pit 16 Discharge port

Claims (1)

In the method of desiliconization and desulfurization using a hot metal ladle as a refining vessel in hot metal pretreatment,
The inclination angle θ (°) of the hot metal ladle relative to the lance inserted in the hot metal ladle is inclined within the range of the formula (1),
In carrying out the desiliconization treatment, T.S. is introduced from the charging device installed at the top of the hot metal ladle at the start of the desiliconization treatment. Iron oxide containing Fe = 50-80% by mass is charged in an amount of 1.0-22.2 kg / t, and the height of the oxygen lance disposed on the center side of the hot metal ladle is 0.65-1.50 m, Oxygen gas was blown at an oxygen gas flow rate of the oxygen lance of 0.15 to 0.30 Nm ³ / min · t,
Further, the injection lance disposed on the side of the oxygen lance is immersed in the hot metal so that the discharge angle α of the injection lance satisfies the formula (2), and the immersion depth of the injection lance is 1.5. To 2.0 m, and the nitrogen gas flow rate of the injection lance is 0.0056 to 0.020 Nm ³ / min · t, and the nitrogen gas is blown together with CaO or a mixed powder of CaO and iron oxide, Desiliconization treatment,
In performing the desulfurization treatment, the injection lance is immersed at a depth of 1.5 to 2.0 m while maintaining the discharge angle α (°) of the injection lance at an angle satisfying the expression (2). Nitrogen gas flow rate of 0.0056 to 0.020 Nm ³ / min · t, and mixed powder of CaO and Mg together with the nitrogen gas is blown at a rate of Mg weight of 0.030 to 0.165 kg / min · t. To perform the desulfurization treatment,
A method of desiliconization and desulfurization in a hot metal ladle characterized by tilting the hot metal ladle after the desulfurization treatment and discharging slag with a slag dragger.
3.0 ≦ θ ≦ 9.0 (1)
0 ≦ α ≦ θ + 20 (2)

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