JP2011179041A - Method for removing metal in converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for restraining erosion of a refractory in a converter and also, efficiently removing the stuck metal in the converter, in preliminary dephosphorization for hot metal in which powdery refining agent consisting essentially of CaO such as lime, is blown into the hot metal together with oxygen by using the converter. <P>SOLUTION: The method for removing the stuck metal in the converter is characterized in that in the hot metal preliminary dephosphorization blowing, where after charging the hot metal into the converter-type refining furnace, a top-blowing lance having a nozzle for melting the metal installed on the sidewall is inserted into the refining furnace and the dephosphorization is performed by blowing the powdery refining agent together with the oxygen for blow-refining, from a nozzle for blow-refining installed at the tip-end of the top-blowing lance, the oxygen for melting the stuck metal is injected in the horizontal direction from the nozzle for melting the stuck metal installed on the sidewall during blowing period of the powdery refining agent, and from end of blowing of the powdery refining agent till end of blowing of the oxygen for blow-refining, purge-gas is continuously caused to flow from the nozzle for melting the stuck metal so that the nozzle for melting the stuck metal installed on the sidewall is not closed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  In the converter, when a powder refining agent mainly composed of CaO such as quick lime is sprayed from the lance to the hot metal together with oxygen in the converter to perform the hot metal preliminary dephosphorization process, it is deposited in the converter and at the furnace port at the same time. The present invention relates to a method for removing bullion.

  Part of the hot metal / molten steel and slag scattered by spitting and slopping that occurs during converter blowing is deposited and deposited on the furnace port and the inner wall of the furnace as metal. Spitting occurs particularly when a powder refining agent mainly composed of CaO such as quick lime is sprayed on the molten iron together with oxygen. Hot metal and steel scattered by spitting not only lowers the iron yield, but also increases the amount of deposited metal, which may hinder the introduction of hot metal and scrap, and also repair refractories in the converter. Cause trouble.

  For example, in Patent Document 1, as a technique for removing metal attached to the furnace port during converter blowing, from the oxygen supply nozzle for secondary combustion provided on the side wall of the main lance for blowing, There has been proposed a method for removing metal adhering to the furnace port by heat generated by blowing oxygen for secondary combustion toward the furnace and burning converter exhaust gas in the furnace. However, this technique has a problem in that the furnace interior becomes a high temperature of 2000 ° C. or more due to the secondary combustion, so that the melting loss of the converter mouthpiece and the furnace refractory is remarkable.

  Further, in Patent Document 2 and Patent Document 3, while blowing oxygen gas for blowing from the lower end of the lance to the hot metal, oxygen gas is injected from the outer periphery of the lance toward the inner wall of the furnace to remove the ingot in the furnace. A method has been proposed. Furthermore, in patent document 4, by controlling the metal melt | dissolution oxygen injected toward the furnace inner wall from the outer peripheral part of a lance independently from the oxygen for blowing, A method has been proposed in which the oxygen flow rate is controlled and the in-furnace metal in the furnace is efficiently removed.

JP-A-6-248323 JP-A-8-127812 Japanese Patent Laid-Open No. 10-317045 JP 2000-96119 A

  When the powder refining agent is sprayed onto the hot metal together with oxygen, the metal is attached to the furnace more intensely than when only the oxygen is blown, so it matches the supply of the powder refining agent. Therefore, it is necessary to properly determine the supply method of oxygen for melting metal.

  However, Patent Documents 2 to 4 describe the ratio of the amount of oxygen for blowing and the amount of dissolved oxygen for the bullion and the regulation of the amount of dissolved oxygen for the bullion depending on the blowing period. There is no description regarding a method for efficiently removing the ingot in the furnace when the powder refining agent is sprayed on the hot metal together with oxygen.

  Further, the furnace body shape of the converter is such that the inner diameter thereof decreases from the middle part toward the furnace port. Therefore, when the bullion melting nozzles are installed at a plurality of locations at different heights in the upper portion of the lance side wall in the vertical direction from the blowing nozzle at the lower end of the upper lance, the same amount of oxygen is extracted from the bullion melting nozzle. When the gas is injected, the refractory melts away as it approaches the furnace port. In order to suppress such non-uniform progression of the refractory erosion, it is necessary to change the amount of oxygen for melting the metal as it decreases in the vertical direction toward the upper furnace port. However, Patent Documents 1 to 4 do not describe such technical matters.

  The present invention has been made in view of these problems, and hot metal preliminary dephosphorization blowing (converter blowing) in which a powder refining agent mainly composed of CaO such as quick lime is sprayed to hot metal together with oxygen using a converter. ), The melting loss of the refractory in the furnace is suppressed, and the purpose is to efficiently remove the adhered metal in the converter.

  In order to solve the above-mentioned problems, the present inventor quantitatively evaluates and analyzes the adhesion state of the ingot in the furnace, and further effectively removes the adhering ingot while suppressing refractory melting. And the present invention was completed.

1. Configuration of the equipment used for the examination In the converter blowing in which a powder refining agent mainly composed of CaO such as quick lime is sprayed on the molten iron together with oxygen, the powder refining agent and While oxygen is sprayed on the hot metal, oxygen gas is sprayed from the metal melting nozzles installed at different positions on the upper side wall of the upper blowing lance toward the inner wall of the furnace where the metal is attached. To dissolve and remove the adhered metal. At that time, the relationship with the occurrence of spitting associated with the supply of the powder refining agent causing the adhesion of the metal is considered. In addition, since the inner diameter of the furnace is reduced in the vicinity of the furnace mouth, the inner diameter of the metal melting nozzle installed at each height of the side wall of the upper blowing lance is set vertically above the blowing nozzle of the upper blowing lance. Toward this, use a top blow lance that varies according to the distance from the furnace inner wall.

2. Quantitative evaluation of adhesion status of ingots in furnace (Dust generation survey)
In order to quantitatively evaluate the adhesion state of ingots in a furnace (dephosphorization blowing) in which a powder refining agent containing CaO as the main component, such as quick lime, is sprayed together with oxygen, the amount of dust generated during blowing is first investigated. did.

2-1. Investigation Method In this investigation, the amount of hot metal subject to converter blowing was 80 t. The hot metal components before the start of blowing and after the end of blowing were as shown in Table 1. The basicity of the slag after the end of blowing is as follows: bulk quicklime (particle size: 10-50 mm, CaO: 90% by mass, balance: CO ₂ and impurities) and powdered quicklime (particle size: 150 μm or less, CaO: 90% by mass) , The balance: CO ₂ and impurities), and the mass concentration ratio by slag analysis was adjusted so that CaO / SiO ₂ was in the range of 2.2 to 2.8. The powder refining agent (powder quicklime) was investigated both when it was supplied and when it was not supplied.

The top blowing lance used was a nozzle formed with four Laval nozzles having a diameter of 36 mm and an inclination angle of 6 ° as a nozzle for blowing. The oxygen flow rate for blowing was constant at 8000 Nm ³ / hr regardless of whether or not the powder refining agent was supplied. The blowing time was 10 minutes.

  The supply conditions of the powder refining agent were such that the powdered quicklime supply rate was 300 kg / min, and the powdered quicklime blowing time was 5.0 minutes after 2.0 minutes from the start of blowing.

  The dust generation amount was evaluated by collecting dust collected during blowing at intervals of 1 minute from the start of blowing and measuring the dust (T.Fe) content in the collected dust as an index.

2-2. Survey results (1) When powder refining agent is not supplied (when converter is blown by supplying only oxygen)
FIG. 1 shows the elapsed time of blowing and the T.V. in the collected water when only the oxygen is supplied from the top blowing lance and the converter is blown. It is a figure which shows the relationship with Fe content rate.

  First, when the converter was blown only with oxygen, as shown in FIG. 1, the dust generation amount tended to decrease as the blowing progressed. This result shows that when blowing only with oxygen, spitting during blowing is suppressed as the refining agent hatches, so the formation and growth rate of ingots in the furnace during the first half of blowing is reduced. It is thought that it corresponds to the knowledge about conventional spitting that it is fast.

(2) When a powder refining agent is supplied FIG. 2 shows a case where a powder refining agent mainly composed of CaO, such as quick lime, is sprayed onto hot metal together with oxygen from the top blowing lance to perform converter blowing. Elapsed time and T. It is a figure which shows the relationship with Fe content rate.

  On the other hand, when the powder refining agent is sprayed onto the hot metal together with oxygen, as shown in Fig. 2, it is recognized that the amount of dust generated is large during the supply of the powder refining agent regardless of the progress of the blowing. It was. This is inferred from the correspondence with the case where the converter blowing is performed only with oxygen, and in the case of the blowing where the powder refining agent is sprayed on the hot metal together with oxygen, regardless of the progress of the blowing. It is considered that a lot of spitting occurred during the supply of the powder refining agent. If there is a lot of spattering of hot metal, etc. due to spitting, formation and growth of ingots in the furnace will become intense, so it is necessary to continue supplying (injecting) oxygen for melting metal during the supply of powder refining agents. Become.

  However, as shown in FIG. 2, the amount of dust generated decreased after the supply of the powder refining agent was completed. This is because the powder refining agent rapidly hatches after spraying on the hot metal. Therefore, it is not necessary to inject oxygen for melting the metal after the supply of the powder refining agent is completed. If the metal melting oxygen continues to be injected even after the supply of the powder refining agent, it is considered that the melting of the furnace wall refractory may progress.

2-3. Consideration From the above results, in the hot metal preliminary dephosphorization blowing in which a powder refining agent mainly composed of CaO such as quick lime is blown together with oxygen, the ingot in the furnace is effectively suppressed while suppressing the melting of the furnace wall refractory. As a method of removal, during the supply of the powder refining agent, an appropriate amount of metal for dissolving the metal ingot is injected from the nozzle for dissolving the metal in the upper portion of the side wall of the top blowing lance, and after the supply of the powder refining agent is blown. Until the end of smelting, the idea is to continue the flow of a purge gas such as nitrogen or air so that the metal melting nozzle does not block, or to reduce the oxygen gas flow rate to the extent that the furnace wall refractory does not melt, The present invention (see (1) below) was completed through examination.

  It should be noted that during the period from the start of spraying of oxygen for blowing to the start of supplying the powder refining agent, an appropriate amount of metal for dissolving the metal can be injected from the nozzle for dissolving the metal, or the purge gas can be kept flowing. good.

3. 3. Examination of methods for effectively removing adhered metal 3-1. Experimental Method FIG. 3 is a conceptual diagram of the blowing device when the metal melting nozzles are installed at a plurality of locations having different heights on the upper portion of the lance side wall in the vertical direction from the blowing nozzle at the lower end of the upper blowing lance. is there. As shown in FIG. 3, converter blowing is performed by inserting the top blowing lance 4a into the converter 3a and spraying oxygen on the molten iron 1a. The basic configuration of the blowing device shown in FIG. 3 is the same as that of the blowing device shown in FIG. 6 described later, and a substantially the same part is denoted by a in FIG.

  The converter 3a includes a furnace body straight body part 12a having a constant inner diameter from the bottom part to the middle abdomen, and a furnace body inclined part 13a whose inner diameter decreases from the middle part toward the furnace port side. In general, hot metal or the like scattered by spitting during converter blowing is likely to deposit on the furnace body inclined portion 13 of the furnace inner wall surface 7a as the adhesion metal 8a. In order to dissolve and remove the adhering metal 8a formed on the furnace body inclined portion 13, the position of the metal melting nozzle 6a installed on the upper side wall of the upper blowing lance 4a is set to the height of the furnace body inclined portion during blowing. It is desirable to be

  Therefore, as shown in FIG. 3, the height of the furnace body inclined part lower end 9 a, furnace body inclined part central part 10 a and the furnace mouth part 11 a at the upper part of the side wall of the upper blowing lance 4 a during converter blowing. In each case, 12 metal melting nozzles 6a were installed in the vertical direction of the blowing nozzle 5a. The inner diameters of all the metal melting nozzles 6 a were 4.4 mm, and the same amount of oxygen gas was injected from the various metal melting nozzles 6 a toward the furnace inner wall surface 7 a of the furnace body inclined portion 13.

3-2. Experimental Results First, by changing the oxygen flow rate of the gold melting nozzle 6a in each place, the dissolved amount of the adhering metal 8a in the vicinity of the furnace body inclined part lower end 9a, the furnace body inclined part central part 10a, and the furnace port part 11a, and The amount of erosion loss of the furnace wall refractory was evaluated.

  The “bulb melting index” was used as an evaluation index for the amount of adhesion metal dissolution, and the “furnace wall refractory melting rate index” was used as an evaluation index for the melting loss of furnace wall refractories.

  The “metal dissolution index” means that the level before dissolution removal is 0, the level at which complete dissolution is possible is 10.0, and the thickness of the adhesion metal is measured by visual observation in the furnace and thickness measurement using a profile meter. The amount of dissolution is indexed.

`` Furnace wall refractory erosion rate index '' refers to the thickness of the furnace wall refractory when the surface of the furnace wall refractory can be confirmed by visual confirmation inside the furnace, using a profile meter. When the oxygen flow rate of the melting nozzle 6a is 40 Nm ³ / hr, the melting rate (mm / ch) of the furnace wall refractory in the vicinity of the lower end of the inclined section of the furnace body (per thickness of the furnace wall refractory thickness per blowing Change amount) is a reference value “1”.

FIG. 4 is a diagram showing the relationship between the oxygen flow rate per one hole for dissolving a metal bar and the metal dissolution index. From FIG. 4, for example, in order to remove the adhering metal on the inner wall surface of the furnace in the whole area near the furnace port part, the middle part of the furnace body inclined part, and the lower end of the furnace body inclined part, the oxygen flow rate per nozzle for melting the metal bar is changed. It turns out that it is necessary to set it as 40 Nm < ³ > / hr or more.

FIG. 5 is a diagram showing the relationship between the oxygen flow rate per one hole for melting a metal bar and the furnace wall refractory melt rate index. From FIG. 5, when the oxygen flow rate per nozzle for melting the metal is 40 Nm ³ / hr or more, the melting loss of the furnace wall refractory near the furnace port is near the middle of the furnace body slope and near the lower end of the furnace body slope. It turns out that it progresses faster than. This is because the distance between the furnace inner wall surface of the furnace body inclined portion and the metal melt melting nozzle is reduced toward the furnace port.

3-3. Discussion From the results shown in FIG. 4 and FIG. 5, it was found that there is a limit to efficiently removing the adhering metal on the inner wall surface of the furnace inclined portion of the converter.

  In addition, based on these results, when installing the metal melting nozzles at different locations on the lance side wall in the vertical direction from the blowing nozzle at the lower end of the upper blowing lance toward the vertical direction, By varying the inner diameter according to the distance between the gold melting nozzle and the inner wall surface of the furnace, the melting of the furnace wall refractory in the vicinity of the furnace port is suppressed, while the inner wall surface of the furnace body inclined surface is suppressed. The present invention (see (2) below) was completed through an investigation and examination, conceived of a method for effectively removing the adhered metal.

4). SUMMARY OF THE INVENTION The present invention has been made on the basis of the above findings, and the gist of the present invention resides in the method for removing in-converter ingots shown in the following (1) and (2).

(1) After charging the hot metal into the converter type refining furnace, insert the top blowing lance with the metal melting nozzle on the side wall into the refining furnace and install it at the tip of the top blowing lance In hot metal preliminary dephosphorization blowing, in which a powder refining agent is sprayed on hot metal together with blowing oxygen to remove phosphorus, during the spraying period of the powder refining agent, a ground metal melting nozzle installed on the side wall From the end of spraying of the powder refining agent to the end of spraying of the oxygen for melting, gold melting oxygen is injected in the horizontal direction so that the metal melting nozzle installed on the side wall is not blocked. A method for removing metal deposits in a converter, characterized in that a purge gas continues to flow from a gold melting nozzle.

(2) The converter type refining furnace has a furnace body inclined portion at the upper part, and a metal melting nozzle is installed at a plurality of positions having different heights on the side wall of the upper blowing lance, The inner diameter of the metal melting nozzle at the position where the distance between the nozzle outlet and the converter wall surface is the largest is Ro (mm), and the distance between the outlet of the metal melting nozzle and the converter wall surface is Do (mm), Ri (mm) is the inner diameter of the nozzle for melting the bullion at the height position of the inclined section of the furnace body above the nozzle for melting the bullion at the position where the distance between the outlet of the nozzle for melting the bullion and the wall surface of the converter is the largest. When the distance between the outlet of the nozzle for melting the metal bar and the converter wall surface is Di (mm), the metal bar so that the relationship between Ro, Do and Ri, Di satisfies the following formula (1). The hot metal preliminary dephosphorization blowing is performed using an upper blowing lance provided with a melting nozzle. Preparative feature to claim 1 converter in adhesion bullion removal method Ro · of which are listed at (Di / Do) ≦ Ri ≦ Ro ... (1)

  According to the method for removing metal in the converter of the present invention, in the converter blowing in which a powder refining agent mainly composed of CaO such as quick lime is sprayed on the hot metal together with oxygen, the wear of the furnace wall refractory is suppressed. The ingot in the furnace can be effectively removed, and the blockage of the nozzle for melting the ingot can be suppressed, so that the productivity of the converter can be greatly improved.

Blowing elapsed time and T. in the dust collection water when only the oxygen is supplied from the top blowing lance and the converter is blown. It is a figure which shows the relationship with Fe content rate. When the powder refining agent mainly composed of CaO, such as quick lime, is sprayed on the hot metal together with oxygen from the top blowing lance, the elapsed time of the blowing and the T.V. It is a figure which shows the relationship with Fe content rate. It is a conceptual diagram of the blowing apparatus at the time of installing the nozzle for metal melt | dissolution in the several location from which the height of the lance side wall upper part differs in the perpendicular direction from the nozzle for blow blowing of an upper blowing lance lower end. It is a figure which shows the relationship between the oxygen flow rate per nozzle | hole for metal melt | dissolution, and a metal melt | dissolution index. It is a figure which shows the relationship between the oxygen flow rate per nozzle hole for metal | molten metal melt | dissolution, and a furnace wall refractory material erosion rate index | exponent. It is a conceptual diagram of the example of an apparatus used in order to implement this invention. It is a figure which shows the metal dissolution rate index | exponent in each position in a furnace inner wall surface. It is a figure which shows the relationship between the internal diameter of a nozzle for melt | dissolving a metal bar, and a metal melt | dissolution rate index | exponent in a furnace body inclination part center part and a furnace port part. It is a figure which shows the furnace wall refractory melting rate index | exponent in each position in a furnace inner wall surface. It is a figure which shows the relationship between the internal diameter of the nozzle for melt | dissolving a metal bar, and a furnace wall refractory melting rate index | exponent in a furnace body inclination part center part and a furnace port part.

  The reason why the method of the present invention is defined as described above and preferred embodiments of the present invention will be described below.

1. Apparatus for Implementing the Present Invention FIG. 6 is a conceptual diagram of an example apparatus used to implement the present invention. The converter 3 comprises a furnace body straight body portion 12 having a constant inner diameter, and a furnace body inclined portion 13 which is disposed on the upper portion of the furnace body straight body portion 12 and whose inner diameter decreases toward the upper side. A furnace port is provided at the upper end of the portion 13. At the time of carrying out the blowing, an upper blowing lance 4 is inserted into the furnace from the furnace port of the converter 3 in which the hot metal 1 and the refining agent 2 are charged.

  The upper blowing lance 4 is provided with a blowing nozzle 5 at the lower end for blowing a powder refining agent mainly composed of CaO, such as blowing oxygen and quick lime, to the hot metal. Moreover, the metal melt | dissolution nozzle 6 which can inject oxygen gas toward the furnace inner wall surface 7 in the several predetermined position from which the height differs from the lower end of the side wall of the upper blowing lance 4 is provided.

  The structure of the top blowing lance 4 is such that piping for supplying oxygen gas and a powder refining agent is connected to the nozzle 5 for blowing, piping for supplying oxygen gas and purge gas is connected to the nozzle 6 for melting metal, and A quadruple pipe structure in which a cooling water supply pipe and a drain pipe for the blow lance 4 are arranged inside is adopted. As described above, the top blowing lance 4 has a structure that can control the supply path of the metal for dissolving the base metal independently from the supply path of the blowing oxygen.

  The object of the method of the present invention is to remove the adhered metal 8 deposited on the inner wall surface 7 of the converter 3 by using the top blowing lance 4. Therefore, after inserting the top blowing lance 4 into the converter 3, the powder refining agent mainly composed of CaO such as oxygen and quick lime is blown from the blowing nozzle 5 to the molten iron 1, and at the same time, Oxygen is injected from the gold melting nozzle 6 onto the furnace inner wall surface 7. At this time, since the surface temperature of the adhesion metal 8 deposited on the inner wall surface 7 of the furnace is in a high temperature state, the adhesion metal 8 reacts with the oxygen blown from the metal melting nozzle 6 and is melted and melted. The

  In the present invention, the powder refining agent sprayed onto the hot metal 1 together with oxygen from the top blowing lance 4 may be anything as long as it can serve as a dephosphorizing agent. Specifically, examples thereof include quick lime, limestone, converter slag, and the like containing 40 mass% or more of CaO and having a particle size of 1 mm or less.

2. Inner diameter of metal melting nozzle 2-1. Hypothesis Here, as described above with reference to FIG. 1 and FIG. 2, it is known that spitting frequently occurs during the spraying of the powder refining agent. From this, it can be estimated that the growth of the adhesion metal is large during the spraying of the powder refining agent. Therefore, it can be predicted that it is effective to limit the injection of oxygen from the metal melting nozzle for melting the adhered metal only during that period (while the powder refining agent is being sprayed).

  Also, adjust the inner diameter of the metal melting nozzle installed on the top of the lance side wall in the vertical direction from the blowing nozzle at the lower end of the upper blowing lance according to the distance between the outlet of the metal melting nozzle and the inner wall of the furnace. By doing this, it is possible to remove the adhering metal effectively while suppressing the melting of the furnace wall refractory at the same time on the entire inner wall surface of the furnace slope part where the distance from the metal melting nozzle is not constant. It is thought that it becomes.

2-2. Survey method Therefore, when the nozzles for melting the metal bullion are installed at multiple locations with different heights on the top of the lance side wall in the vertical direction from the nozzle for blasting the top blowing lance, The inner diameter of the nozzle for melting the metal bar at the position where the distance between the outlet and the inner wall surface of the furnace is the greatest (in FIG. 6, the lowest one of the nozzles for melting the metal bar 6 arranged in three stages) is Ro (mm), The distance between the outlet of the metal melting nozzle and the inner wall of the furnace is Do (mm), and the metal melting nozzle at the position where the distance between the outlet of the metal melting nozzle and the inner wall of the furnace during blowing is the largest. Ri (mm) is the inner diameter of the nozzle for melting the ingot at the height of the inclined section of the furnace body (in FIG. 6, the upper two of the nozzles for melting the ingot 6 arranged in three stages in FIG. 6). , The outlet of the nozzle for melting the metal and the inner wall surface of the furnace sloped part When the distance is Di (mm), the inner diameter of the metal melting nozzle 6 at each height is changed, and the oxygen for melting the metal is injected at a predetermined constant flow rate so that appropriate values of Ro, Do, Ri and Di are obtained. The relationship was investigated.

(1) Hot metal conditions In this investigation, the amount of hot metal subject to converter blowing (dephosphorization blowing) was 80 t. The hot metal components before the start of blowing and after the end of blowing were as shown in Table 2. The basicity of the slag after the end of blowing is as follows: bulk quicklime (particle size: 10-50 mm, CaO: 90% by mass, balance: CO ₂ and impurities) and powdered quicklime (particle size: 150 μm or less, CaO: 90% by mass) , The balance: CO ₂ and impurities), and the mass concentration ratio by slag analysis was adjusted so that CaO / SiO ₂ was in the range of 2.2 to 2.8.

(2) Blowing conditions For the top blowing lance, a nozzle having four Laval nozzles having a diameter of 36 mm and an inclination angle of 6 ° was used at the tip as a nozzle for blowing. As shown in Table 3, the oxygen flow rate for blowing was constant at 8000 Nm ³ / hr regardless of whether or not the powder refining agent was being sprayed in any of the examples. The blowing time was 10 minutes.

  The conditions for supplying the powder refining agent (the powdered quicklime) were a blowing rate of 300 kg / min and a blowing timing of 5 minutes after 2.0 minutes from the start of blowing. Moreover, the nozzle for blowing was 36 mm in inner diameter, and the number was four.

(3) Metal Melting Conditions The metal melting nozzle has a positional relationship with the furnace body during blowing, the furnace sloped lower end 9 in FIG. 6, the furnace sloped central part 10, the furnace port ( It was installed so that it might become three places of the height of the furnace body inclination part top part) 11. Table 3 shows the number, shape, inner diameter, and distance between the nozzle outlet and the converter inner wall of the nozzle for melting the metal during blowing at each installation location.

  The oxygen for melting the bullion was injected almost horizontally from the nozzle for melting the bullion toward the adhering bullion formed on the inner wall surface of the furnace. The injection timing of the metal melting oxygen is set to coincide with the supply period of the powder refining agent (powder quicklime), and the purge gas is supplied from the end of the supply of the powder refining agent to the end of the supply of the metal for melting the metal. It was made into the basic embodiment of the Example. By flowing the purge gas, blockage of the metal melting nozzle during the period from the end of supplying the powder refining agent to the end of supplying oxygen for dissolving the metal can be suppressed. However, in some examples, the period was from the start of blowing (starting of blowing) to the end of blowing (end of blowing) from the top blowing lance (“comparison method” shown in Table 3). It was confirmed that there was no practically significant difference between some examples (comparative method) and other basic embodiments in the change of the hot metal component due to dephosphorization.

Regarding the flow rate of the metal melting oxygen, the metal melting nozzle at the position where the distance between the outlet of the metal melting nozzle and the inner wall of the furnace during blowing is the largest (the height of the lower end of the inclined section of the furnace body). ) Was fixed at 40 Nm ³ / hr. This was previously confirmed in FIG. 4 that it was necessary to remove the adhering metal on the inner wall surface of the furnace in the whole area near the furnace mouth, the middle of the furnace slope, and the lower end of the furnace slope. This is the minimum value of 40 Nm ³ / hr or more, which is the oxygen flow rate per nozzle hole, and is a value considering suppression of melting damage of the furnace wall refractory.

  In addition, the amount of dissolved ingot metal and the furnace wall refractory when the inner diameter Ri (mm) of the ingot nozzle for melting is located at the center of the furnace body inclined portion and the height of the furnace mouth portion. The amount of erosion loss was evaluated. Table 3 shows the blowing conditions and the metal melting conditions for the examples of the “conventional method”, “comparative method”, and “present invention examples 1 to 6”.

  In all the examples, the dephosphorization blowing was performed with the same supply conditions for blowing oxygen and powdery quicklime.

  The “conventional method” is an example using an upper blowing lance that does not have a metal melting nozzle.

The “comparative method” is an example using an upper blowing lance having a nozzle for melting a metal, and the distance from the outlet of the nozzle for melting a metal during blowing to the inner wall surface of the furnace is 1010 mm (of the furnace port Height), 1340 mm (height of the central part of the furnace body inclined part), and 1680 mm (height of the lower end of the furnace body inclined part (the height of the straight body part of the converter inner wall and the joint part of the inclined part)). The metal melting nozzles all had an inner diameter of 4.4 mm, and 12 nozzles were installed at each height. Injection velocity bullion dissolved oxygen (oxygen-flow-rate) is set to 40Nm ³ / hr × 12 pieces × 3 points = 1440Nm ³ / hr in total, the injection timing was from the beginning to the end of blowing oxygen supply.

“Invention Example 1” is an example using an upper blowing lance having the same metal melting nozzle as the “comparative method”, and the supply conditions of the metal melting oxygen are different. In “Invention Example 1”, the supply rate of the base metal dissolving oxygen was 1440 Nm ³ / hr in total, and the supply period was from the start to the end of the supply of powdered quicklime (powder refining agent). Nitrogen was used as the purge gas from the metal melting nozzle, and the supply period was the period from the end of supplying the powder refining agent to the end of supplying oxygen for dissolving the metal.

  In addition, nitrogen was poured from the nozzle for melt | dissolving ingots from the start of the supply of oxygen for blowing to the start of supply of powdered quicklime.

“Invention Example 2” to “Invention Example 6” are examples in which only the top blowing lance was changed among the conditions of “Invention Example 1”. The top blow lance used in “Invention Example 2” to “Invention Example 6” has an inner diameter of the nozzle for melting the metal bar at the height of the central portion of the furnace body inclined portion and the height of the furnace mouth portion. It was smaller than that used in Invention Example 1 ”. However, the flow rate of the metal melting oxygen per hole of the metal melting nozzle at the height near the lower end of the furnace body sloping part (the straight part of the inner wall of the converter and the joint of the sloping part) is constant at 40 Nm ³ / hr. It was.

2-3. Investigation Result (1) Dissolution of Adhesive Metal FIG. 7 is a diagram showing a metal dissolution rate index at each position on the inner wall surface of the furnace.
FIG. 8 is a diagram showing the relationship between the inner diameter of the metal melting nozzle and the metal melting rate index at the central part of the furnace body inclined portion and the furnace port.

  In FIG. 7 and FIG. 8, the vertical axis is the ingot dissolution rate index, and the scale of the ingot dissolution rate index is blown 1 when the change in the thickness of the attached ingot is measured by setting a certain point. The amount of change per rotation was “mm / ch”. The adhesion metal on the inner wall of the furnace is formed on the entire circumference of the side wall so as to hang down from the furnace mouth, but the thickness of the adhesion metal is not necessarily uniform and tends to be thick on the trunnion side. This is because it is difficult and meaningless to calculate an accurate measurement average value of the change in thickness of the film.

  The thickness of the adhesion metal can be measured by using a laser distance meter or the like. Here, as shown in Table 3, the metal dissolution rate index at the height of the lower end of the inclined portion of the furnace body in the above comparative method is calculated. The reference value was “1”. The case of “invariant thickness” was set to “0”.

  In the conventional method, the index is “negative” because the thickness of the attached metal changes in the direction of increasing thickness. In the comparative method and Examples 1 to 6 of the present invention, the index is “positive” because the thickness of the adhesion metal changes in the direction of thinning.

  From FIG. 7, it can be seen that in the conventional method, the thickness of the deposited metal at each position in the converter changes in an increasing direction, and in particular, the adhesion of the metal at the furnace port is large. This is considered to indicate that spitting is intense as the powder refining agent is sprayed onto the hot metal, and the hot metal and the like scattered thereby jumps toward the furnace port.

  On the other hand, in the comparative method of injecting (supplying) oxygen for melting the metal bar toward the inner wall surface of the furnace and the present invention example 1 to the present invention example 6, it is clear that the adhering metal can be dissolved. The dissolution effect of was great. In the comparative method, a tendency that the dissolution rate was higher in the upper part of the furnace was recognized.

  It can be seen that Example 1 of the present invention had a metal dissolution effect almost equivalent to that of the comparative method, although the injection of oxygen for melting the metal was stopped after the supply of powdered quicklime was stopped.

  From FIG. 8, in Invention Example 2 to Invention Example 6, as the inner diameter Ri (mm) of the metal melting nozzle is decreased, the metal melting speed decreases, and Ri = Ro · (Di / Do). When Ri was made smaller than the conditions satisfying the condition, the metal dissolution rate tended to be extremely reduced.

  The centerline flow velocity of the oxygen gas injected from the various gold melting nozzles at each position on the inner wall surface of the furnace is proportional to the inner diameter (R) of the nozzle and inversely proportional to the distance (D) between the nozzle outlet and the inner wall surface of the furnace. .

Therefore, it is considered desirable to satisfy the conditions shown in the following (a) to (c).
(A) The flow rate per unit hole of oxygen for melting ingots supplied from a nozzle for melting ingots installed at the position where the distance between the outlet of the nozzle for melting ingots and the inner wall surface of the furnace is the largest. In the case where the attached metal can be removed and the flow rate is fixed at the minimum flow rate in consideration of the suppression of furnace wall refractory melting,
(B) In the case of reducing the inner diameter Ri (mm) of the metal melting nozzle arranged at the height of the upper part of the furnace inclined portion where the distance between the nozzle outlet for the metal melting and the wall surface of the furnace is reduced,
(C) Supply from a metal melting nozzle installed at a position where the distance between the outlet of the metal melting nozzle and the wall of the furnace inner wall is at least the centerline flow velocity of the metal melting oxygen at each position of the furnace wall. It should be equal to or higher than the centerline flow velocity on the inner wall of the furnace melting wall.

That is, it is desirable to satisfy the following conditions (d) to (g).
(D) In the case where nozzles for melting metal are installed at a plurality of locations having different heights on the upper portion of the lance side wall in the vertical direction from the nozzle for blowing at the lower end of the upper blowing lance,
(E) The inner diameter of the metal melting nozzle at the position where the distance between the metal outlet nozzle outlet and the furnace inner wall surface during blowing is the largest is Ro (mm), the outlet of the metal melting nozzle outlet and the furnace inner wall surface And the distance to Do (mm)
(F) Nozzle melting nozzle at the height of the furnace body inclined portion, which is disposed above the bullion melting nozzle at the position where the distance between the bulge melting nozzle outlet and the furnace inner wall surface is the largest during blowing When the inner diameter of Ri is (mm) and the distance between the outlet of the metal melting nozzle and the furnace inner wall surface of the furnace body inclined portion is Di (mm),
(G) From the viewpoint of the dissolution rate of the adherent metal formed on the inner wall surface of the furnace, Ri must satisfy the following formula (1).
Ro · (Di / Do) ≦ Ri ≦ Ro (1)

(2) Melting of furnace wall refractory FIG. 9 is a diagram showing the furnace wall refractory erosion rate index at each position on the inner wall surface of the furnace. FIG. 9 is a diagram showing the correspondence with FIG. The meaning of each legend is the same as in FIG.
FIG. 10 is a diagram showing the relationship between the inner diameter of the metal melting nozzle and the furnace wall refractory erosion rate index at the central part of the furnace body and the furnace port part.

  In FIGS. 9 and 10, the vertical axis represents the furnace wall refractory erosion rate index. Here, the average furnace wall refractory erosion rate at the lowest part of the sloped portion of the furnace body in the above comparative method is expressed as an index. The reference value was “1”. When measuring the thickness of the furnace wall refractory, the thickness of the furnace wall refractory has increased compared to the state before adhesion of the bare metal, and the adhered inner metal remains by visually observing the inner wall of the furnace. In such a case, the amount of erosion of the furnace wall refractory was regarded as 0 mm, and the index was evaluated as “0”.

  From FIG. 9, in the conventional method, since the adhesion of the base metal basically tends to progress, the melting loss of the furnace wall refractory is not recognized as a whole.

  On the other hand, it can be seen that in the comparative method of injecting oxygen for melting the metal bar toward the inner wall surface of the furnace and Examples 1 to 6 of the present invention, the furnace wall refractories tend to be more easily damaged than in the conventional method. . Among them, in the comparative method in which the oxygen for melting the metal is continuously injected throughout the supply of the oxygen for blowing, the melting loss of the furnace wall refractory was remarkable.

  However, in Example 1 of the present invention in which the injection of oxygen for melting the bullion was stopped after the supply of powdered quicklime was stopped, the furnace wall refractory erosion rate decreased. However, the furnace wall refractory erosion rate near the central part of the furnace body and near the furnace port was larger than that near the lower end of the furnace body slope.

  From FIG. 10, in the present invention example 2 to the present invention example 6, it was recognized that the furnace wall refractory erosion rate tends to decrease as the inner diameter Ri (mm) of the metal melting nozzle is reduced. This effect was generally recognized as long as the inner diameter Ri (mm) of the metal melting nozzle satisfies the above formula (1).

  Ideally, if the inner diameter Ri (mm) of the metal melting nozzle is set as Ro · (Di / Do), the melting of the refractory of the furnace wall is most suppressed and the molten metal is effectively dissolved. Removal is considered possible. However, since the amount of attached metal differs depending on the location of the furnace body, the inner diameter Ri (mm) of the metal melting nozzle is appropriately set within the range satisfying the above expression (1) depending on the amount of attached metal in the furnace. Just choose.

2-4. Consideration From the above, considering the results of this survey in general, the following operation method is considered appropriate.
1) First, if no oxygen for melting metal is used at all, the metal in the furnace will gradually grow and hinder the operation. Can be dissolved as shown in FIG.
2) However, the oxygen for melting the metal is accompanied by an adverse effect that promotes the melting of the refractory. Therefore, even when it is desired to promote the dissolution of the adhered metal, the method of the present invention example 1 (the supply period of the metal for dissolving the metal is set from the start to the end of the supply of the powder refining agent, and from the end of the supply of the powder refining agent. By applying a method in which the purge gas is supplied from the metal melting nozzle until the supply of the metal melting oxygen is completed, refractory material melting can be relatively suppressed.
3) On the other hand, in the case where it is not necessary to rush the dissolution of the adhering metal, the method of the present invention example 2 to 6 of the present invention is applied to dissolve the adhering metal and the furnace wall refractory. The erosion loss can be brought close to the level when not using oxygen for dissolving the metal. Here, when the oxygen gas flow rate of the inner diameter Ro of the lowermost metal melting nozzle is set to an amount capable of dissolving and removing the adhered metal while suppressing the melting of the furnace wall refractory, The inner diameter Ri (mm) of the nozzle for melting the metal at the height of the part or the furnace port may be appropriately selected within the range satisfying the following expression (1).
Ro · (Di / Do) ≦ Ri ≦ Ro (1)
4) Further, in the above investigation examples, in the inventive examples 1 to 6, the injection of the metal for dissolving the metal bar was continued throughout the supply of the powdered quicklime. However, it is obvious that both the metal melting rate and the furnace wall refractory melting rate can be reduced by appropriately shortening the oxygen supply time during the supply period of powdered quicklime.

  In order to confirm the effect of the method of the present invention, the following converter blowing test was performed, and the formation status of the adhesion metal on the inner wall surface of the furnace and the erosion status of the furnace wall refractory were evaluated.

1. Test conditions (1) Hot metal conditions The amount of hot metal subject to converter blowing (dephosphorization blowing) was 80 t. The hot metal components before the start of blowing and after the end of blowing were as shown in Table 4. The basicity of the slag after the end of blowing is as follows: bulk quicklime (particle size: 10-50 mm, CaO: 90% by mass, balance: CO ₂ and impurities) and powdered quicklime (particle size: 150 μm or less, CaO: 90% by mass) , The balance: CO ₂ and impurities), and the mass concentration ratio by slag analysis was adjusted so that CaO / SiO ₂ was in the range of 2.2 to 2.8.

(2) Blowing conditions As the top blowing lance, one having four Laval nozzles having a diameter of 36 mm and an inclination angle of 6 ° was used as a nozzle for blowing at the tip. As shown in Table 3, the oxygen flow rate for blowing was constant at 8000 Nm ³ / hr. The blowing time was 8 to 11 minutes. The powder refining agent was supplied under the conditions of a powdered quicklime (powder refining agent) supply speed of 300 kg / min and a powdery quicklime blowing time of 5 minutes from 1.5 minutes after the start of blowing. Moreover, the nozzle for blowing was 36 mm in inner diameter, and the number was four.

(3) Metal Melting Conditions In the top blowing lance, metal melting nozzles were installed at a plurality of locations having different heights at the upper part of the lance side wall in the vertical direction from the nozzle for blowing. The nozzle for melting the metal during blowing is in a positional relationship with the furnace body, the furnace body inclined part lower end 9 in FIG. 6, the furnace body inclined part central part 10, the furnace port part (furnace body inclined part uppermost part). It was installed to be 3 places at 11 height. The number, shape, inner diameter, and the distance between the nozzle outlet and the converter inner wall of the nozzle for melting metal during blowing at each installation location were as shown in Example 3 of the present invention in Table 3. And from the nozzle for melt | dissolving a bullion, oxygen for melt | dissolving a bullion was injected almost horizontally toward the bullion adhering to the inner wall surface of the furnace, and blowing was performed to remove the deposited bullion.

  The basic embodiment is that the injection period of the metal melting oxygen is set to coincide with the supply period of powdered quicklime (powder refining agent). Further, nitrogen was allowed to flow during the period before and after that.

2. Test result This blowing operation was performed for 100 ch (charge), and the adhesion state of the metal on the inner wall surface of the furnace was measured every 20 ch. As a result, there was no significant change in the thickness of the adhered metal. At the same time, when the erosion status of the furnace wall refractory was also measured, it was confirmed that there was virtually no erosion in about 100 ch blowing as in the conventional operation.

  According to the method for removing metal in the converter of the present invention, in the converter blowing in which a powder refining agent mainly composed of CaO such as quick lime is sprayed on the hot metal together with oxygen, the wear of the furnace wall refractory is suppressed. Therefore, it is possible to effectively remove the ingot in the furnace, and the productivity of the converter can be greatly improved.

1, 1a: hot metal, 2: refining agent, 3, 3a: converter, 4, 4a: top blowing lance,
5, 5a: Nozzle for blowing, 6, 6a: Nozzle for melting metal, 7, 7a: Wall surface of furnace
8, 8a: Adhesion metal, 9, 9a: Lower end of furnace body inclined portion,
10, 10a: furnace body inclined part central part, 11, 11a: furnace port part,
12, 12a: furnace body straight body part, 13, 13a: furnace body inclined part

Claims (2)

After charging the hot metal into the converter type refining furnace, insert the upper blowing lance with the metal melting nozzle on the side wall into the refining furnace, and the powder from the blowing nozzle installed at the tip of the upper blowing lance In hot metal preliminary dephosphorization blowing in which a refining agent is sprayed on hot metal together with oxygen for blowing to dephosphorize,
During the spraying period of the powder refining agent, the metal melting oxygen is sprayed horizontally from the metal melting nozzle installed on the side wall,
From the end of the spraying of the powder refining agent to the end of the spraying of the oxygen for blowing, the purge gas continues to flow from the metal melting nozzle so as not to block the metal melting nozzle installed on the side wall. A feature of the method for removing metal adhering to the converter. The converter type refining furnace has a furnace body inclined part at the top,
On the side wall of the top blowing lance, nozzles for melting the metal are installed at a plurality of positions having different heights,
The inner diameter of the metal melting nozzle at the position where the distance between the outlet of the metal melting nozzle and the converter wall is the largest is Ro (mm), and the distance between the outlet of the metal melting nozzle and the converter wall is Do. (Mm)
Ri (mm) is the inner diameter of the nozzle for melting the bullion at the height position of the inclined section of the furnace body above the nozzle for melting the bullion at the position where the distance between the outlet of the nozzle for melting the bullion and the wall surface of the converter is the largest. When the distance between the outlet of the metal melting nozzle and the converter wall surface is Di (mm),
The hot metal preliminary dephosphorization blowing is performed using an upper blowing lance in which a metal melting nozzle is installed so that the relationship between Ro, Do and Ri, Di satisfies the following formula (1): The removal method of the adhesion metal in the converter according to claim 1, wherein Ro · (Di / Do) ≦ Ri ≦ Ro (1)

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