JP5920026B2 - Hot installation method of converter bottom blowing tuyere - Google Patents

Description

  The present invention is to install a converter bottom blowing tuyere to switch the bottom blowing tuyere to a new bottom blowing tuyere to promote refining by injecting gas into the steel bath from the bottom of the converter and stirring the steel bath. Regarding the method.

In a converter that refines a steel bath by oxygen blowing from the top blowing lance, increase the reaction interface area between the slag and the steel bath present in the converter, or segregation of the steel bath itself, temperature distribution, etc. In order to improve the efficiency of the refining reaction by reducing the dispersion of the steel, a stirring gas is blown into the steel bath from the bottom blowing tuyer provided at the bottom of the converter, and the steel bath is strongly stirred. Yes. Further, not only stirring gas but also refining O ₂ gas is blown from a bottom blowing tuyer provided at the bottom of the converter.

  However, in converter refining using bottom-blown tuyere, the refractory around the bottom-blown tuyere has a higher wear rate than refractories in other parts, so the brick thickness other than the bottom-blown tuyere is sufficient. In spite of this, the furnace operation must be stopped. Thus, various proposals have been made in the past to extend the life of the bottom blow tuyere.

  For example, in Patent Document 1, a drilling brick that becomes a tuyere receiving brick is installed in a place other than the bottom-blown tuyere in advance, so that the wear of the tuyere in use becomes large and it cannot be used. At that time, a technique is disclosed in which the previously installed drilling brick is drilled from the outside of the converter iron skin, a new tuyere is inserted into the grinding hole formed through the drilling, and the converter operation is continued. ing. In this case, the bottom blowing tuyere that cannot be used is blocked by an appropriate refractory material such as a cast refractory material, a spray refractory material, or a spray refractory material. The tuyere receiving brick is a brick that is installed around the tuyere and supports and protects the tuyere.

Further, in Patent Document 2, a worn tuyere is extracted, a refractory material is filled in the extracted gap by a flame spraying method, a tuyere insertion hole is drilled in the filling part, and a new tuyere is formed in the formed drilled part. A technique for inserting a mouth and replacing a tuyere is disclosed.
Further, Patent Document 3 discloses a method of drilling with a drill having a hard tip and a water cooling mechanism in order to dismantle the tuyere bricks of the AOD furnace while hot.

JP-A-9-176720 JP 59-41414 A JP-A-4-138207

  However, when drilling a pre-installed drilling brick or tuyere receiving brick from the outside of the converter as disclosed in Patent Document 1 and Patent Document 2, depending on the drilling method, the shape accuracy of the formed hole may be increased. Since it is low, the gap with the tuyere to be inserted more than necessary becomes larger, and problems such as damage to the drilling brick due to impact during drilling occur. In these cases, wear of the replaced tuyere is promoted, and the usage period of the bottom blown tuyere becomes significantly shorter than the assumed period.

  In particular, when drilling is performed when the brick for drilling is hot, depending on the drilling method, the consumption of the drilling tool is severe, which not only increases the construction cost, but also increases the work time, resulting in an inoperable time for the converter. It was a problem because it would be long. For this reason, as described in Patent Document 3, a method of perforating using a coolant such as water has also been proposed. However, in this method, a reaction between a substance in a refractory and water or a thermal shock caused by cooling is proposed. Since the refractory is damaged, it is limited to the case where the perforated brick is dismantled and removed, and is not applied to the case where it is used again as a lining brick after perforating like a perforated brick.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to provide a perforated brick previously disposed in a portion other than the installation site of the bottom blowing tuyeres at the bottom of the converter, outside the converter. When a new bottom blowing tuyere is inserted into a through hole formed by hot drilling with a drilling machine, the center of the drilling brick is accurately set in a short time. Providing a hot installation method for converter bottom blowing tuyere that can improve the life of bricks after drilling while ensuring the durability of drilling tools when drilling well to form through holes There is to do.

The gist of the present invention for solving the above problems is as follows.
(1) In the refractory layer covering the bottom portion of the converter, a brick for piercing is disposed in advance in a portion other than the installation site of the bottom blowing tuyere, and a new bottom is added to the piercing brick after the use of the converter. In installing the blowing tuyere,
As the perforating brick, a magnesia carbon brick containing metal aluminum: 0.5-3 mass%, metal silicon: 0.1-1 mass% and carbon: 15-25 mass% is arranged, from the outside of the bottom. With respect to the drilling brick, the core bit having a hard segment is drilled while supplying water to the tip of the core bit to form a hole penetrating the refractory layer in the drilling brick. A method for hot installation of a converter bottom blowing tuyere characterized by inserting a new converter bottom blowing tuyere.

(2) The heat of the bottom blowing tuyeres according to (1), wherein the perforating brick is perforated within 20 hours from the end of the last blowing in the converter before the perforating. How to install between.

(3) Hot installation of the converter bottom blowing tuyeres according to (1) or (2) above, wherein the temperature of the base brick for drilling at the start of drilling of the brick for drilling is 500 ° C. or more Method.

  According to the present invention, when a bottom blowing tuyere is newly installed in the converter through the use of the converter, the integrally formed perforated brick that becomes the tuyere receiving brick is combined with diamond abrasive grains. Drilling with a core bit with a hard segment, such as a segment consolidated with an agent, does not mechanically damage the surrounding bricks when drilling, and in the target drilling direction at the center of the drilling brick. A through-hole can be formed with high accuracy along the line. As a result, the life of the inserted tuyere is stably extended and long-term gas blowing is realized.

  In addition, since the drilling is performed while supplying water to the tip of the core bit, the wear of the diamond segment can be suppressed to a minimum even if the hot brick is drilled. Drilling work in time is possible. At this time, since a magnesia carbon brick containing 0.5 to 3% by mass of metal aluminum, 0.1 to 1% by mass of metal silicon and 15 to 25% by mass of carbon is used as a perforated brick, the inclusion of water and bricks The reaction with the substance is suppressed, and the damage to the perforated brick due to the effect of thermal shock of rapid cooling is also suppressed, preventing the life of the tuyere brick installed after perforation and the tuyere receiving brick perforated with the perforated brick. It becomes possible to do.

  Further, the perforating brick is perforated within 20 hours after the final blowing of the converter before perforating, and the temperature at the time of perforating start of the perforating base brick is set to 500 ° C. or more. As a result, the damage to the perforated bricks due to the influence of water has been extensively prevented, so that the life of the tuyere bricks installed after perforation and the tuyere receiving bricks perforated with the perforated bricks can be prevented in advance. be able to.

  According to the present invention, the durability of the drilling tool is ensured without causing problems such as damaging the work bricks around the perforating bricks and tuyere receiving bricks and unnecessarily large grinding holes. On the other hand, the through hole can be formed by accurately drilling the central portion of the perforating brick along the predetermined perforating direction in a short time. Therefore, it is possible to reliably prevent the life of the tuyere bricks installed after drilling and the tuyere receiving bricks drilled with the drilling bricks.

It is sectional drawing which shows a part of converter which has a bottom blowing tuyere. It is sectional drawing for demonstrating the process of the hot installation method of the bottom blowing tuyeres concerning the 1st Embodiment of this invention. It is sectional drawing for demonstrating the punching process of the hot installation method of the bottom blowing tuyeres which concerns on the 1st Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, the structure of a converter having a bottom blowing tuyere will be described. FIG. 1 is an enlarged cross-sectional view of a converter having a bottom blowing tuyere and its tuyere portion.

  As shown in FIG. 1, the converter C includes an iron shell 10 that forms an outer shell thereof, a permanent brick 11 that is lined in a portion that contacts the iron shell 10 inside the iron shell 10, and the permanent brick 11. It has a work brick 12 as a consumable member stretched inside. In FIG. 1, the work brick 11 is one-layered, but may be two-layered or more.

At the bottom of the converter C, a plurality of bottom blowing tuyere 1 is provided. Stirring gases such as Ar gas, N ₂ gas and carbon dioxide gas are supplied to the steel bath in the converter C through the plurality of bottom blowing tuyere 1, and further O ₂ gas for refining from the top blowing lance L, Each is blown and refining is performed while stirring the steel bath.

  The bottom blowing tuyere 1 includes a metal air box 2 provided inside the iron skin 10 at the bottom of the converter C, and a plurality of gases having an inner diameter of 5 mm or less extending upward from the air box 2 into the furnace. A gas introduction pipe 5 for supplying the above-described stirring gas to the wind box 2 from the outside of the furnace, connected to the bottom of the wind box 2 and the tuyere brick 4 covering the gas blow pipe 3. And have. The stirring gas introduced into the wind box 2 through the gas introduction pipe 5 is equalized in the wind box 2 and then blown into the steel bath through the plurality of gas blowing pipes 3. As the bottom blow tuyere, it is preferable to use a structure in which a plurality of gas blowing pipes 3 and tuyere bricks 4 are integrally formed by press molding. Thereby, the gas flow rate fall by the closing of a tuyere can be prevented, suppressing the gas consumption at the time of non-blowing. However, the bottom blowing tuyere 1 is not limited to the one having such a structure, and may be provided with, for example, one gas introduction pipe and a covered refractory covering the gas introduction pipe.

  The bottom-blown tuyere 1 is press-molded so as to be integrated with the tuyere block brick 6 that forms a part of the work brick, and is installed on the base brick 7 integrally with the tuyere block brick 6. The Alternatively, the bottom-blown tuyere 1 may be installed by being inserted into a separately formed tuyere block brick 6 through the base brick 7. In this case, the tuyere block brick 6 functions as a tuyere receiving brick. .

  Here, a flange 100 continuous with the iron skin 10 is provided outside the base brick 7 where the bottom blow tuyere 1 is present. In general, a plurality of the flanges 100 are arranged at appropriate positions on the iron skin 10. A tuyere presser flange cover 13 is bolted to the flange 100. A tuyere presser brick 14 is interposed between the base brick 7 and the wind box 2 and the tuyere presser flange lid 13.

By the way, the tuyere block brick 6 provided around the bottom-blown tuyere 1 is violently eroded from the steel bath strongly stirred by the blowing gas, has a higher erosion rate than other parts, and has a remaining thickness. Decreases rapidly. As a result, the steel bath side tip of the bottom blowing tuyere 1 is also melted, and when the remaining thickness of the bottom blowing tuyere 1 reaches a predetermined value, the gas blowing from the tuyere is stopped and the tuyere is turned off. It becomes necessary to close with refractories. Moreover, since this reduces the number of tuyere, it is necessary to newly install a bottom blowing tuyere at this stage.
Here, when a hole for newly installing a tuyere is drilled with a core bit, the core bit is cooled in order to suppress temperature rise of the core bit and to ensure lubricity during drilling. When the work is carried out between the two, when cooling water is supplied to the refractory brick, the cooling water is also supplied around the refractory brick, and the reaction with the water damages the refractory. The new construction must be done hot. In other words, if the bottom blowing tuyere is installed cold, there is no evaporation of the cooling water as in the case of hot, so that cooling water enters from the joints between the bricks, resulting in damage to the refractory. It will be. Moreover, it is necessary to carry out in order to avoid extending the furnace stop time accompanying cooling and not hindering the productivity of the converter.

Under the above technical background, a tuyere will be newly installed, and the method for hot installation of the bottom blowing tuyere in that case will be specifically described below.
In other words, a drilling brick is placed in advance in a portion different from the bottom blowing tuyer provided at the start of the converter operation, drilled in the drilling brick, and a new bottom blowing tuyere is placed in the through hole of the drilling brick. An embodiment of the present invention to be installed will be described with reference to FIG. FIG. 2 is a cross-sectional view of a new tuyere part for explaining the steps of the hot-blowing tuyere installation method according to the embodiment of the present invention.

  In the new tuyere formation part, when the work brick 12 and the permanent brick 11 are installed in the converter, a brick 6a for drilling made of an integrally molded refractory is arranged in advance. In this case, the piercing brick 6a is disposed at a position where the above-described flange 100 is attached to the iron skin 10 in order to facilitate the piercing work and the tuyere attaching work from the outside of the converter.

  In this embodiment, first, as shown in FIG. 2 (a), a drilling brick 6a having the flange surface of the flange 100 as a reference plane and having the longitudinal direction as the drilling direction is previously set in the longitudinal direction, that is, the drilling direction. The arrangement is perpendicular to the reference plane. In the present embodiment, since the flange 100 is arranged so that the flange surface is parallel to the iron skin 10, the same thing can be said even if the longitudinal direction of the drilling brick 6a is perpendicular to the iron skin 10. It is.

  Usually, the work brick 12 of the converter is arranged in a direction in which the longitudinal direction is perpendicular to the iron skin 10 as shown in FIG. The brick 6a is also installed in a direction in which the longitudinal direction is perpendicular to the iron skin 10. However, when the work brick and the perforating brick are not installed perpendicular to the iron skin 10, the flange 100a. Must be installed in advance in a direction in which the flange surface is perpendicular to the work brick and the drilling brick. In this case, as a matter of course, the flange surface and the iron skin surface are not parallel to each other.

Next, a specific construction method of the perforating brick 6a will be described in detail.
First, the flange 100 and the flange lid 13a are fixed with bolts (not shown), and the presser brick 14a is placed on the flange lid 13a so that the upper surface thereof substantially coincides with the inner surface of the iron skin 10. Next, the perforating base brick 7a is installed on the iron shell 10 and the holding brick 14a so that the surface on which the perforating brick 6a is installed is parallel to the flange surface of the flange 100. Thereafter, permanent bricks 11 are arranged around the perforating base brick 7a to constitute permanent tension of the converter.
In addition, it is a construction method in the case of construction from permanent tension, but when permanent tension has been constructed and only work bricks are re-installed, the used bottom blowing tuyeres and work bricks are removed and installed. The base brick 7a can be reused. At this time, a suitably shaped brick may be inserted into the perforated portion of the perforated base brick 7a and fixed with mortar or the like.

  Next, the perforating brick 6a is installed on the perforating base brick 7a so that its longitudinal axis is perpendicular to the flange surface of the flange 100. Thereafter, the work brick 12 is arranged around the perforating brick 6a to constitute the lining of the converter. At this time, the perforated brick 6a is preferably formed into the same shape as the combination of the tuyere block brick 6, the tuyere brick 4 and the wind box 2. This allows the brick shape to be shared between the tuyere and its surroundings and the perforated brick and its perimeter, which not only reduces the manufacturing cost of bricks, but also increases the freedom of placement of the tuyere and perforating bricks. It can be increased to facilitate changing the arrangement. The perforated brick 6a is preferably one that is integrally press-formed with a uniform material. As a result, it is possible to obtain a strong structure in which defects are not easily generated even after drilling.

  If the perforation brick 6a is arranged in advance so that the perforation direction of the perforation brick 6a is perpendicular to the reference plane, then as shown in FIG. 2 (b), the core bit 15 is placed on the perforation brick 6a from the outside of the iron skin 10. To drill in a direction perpendicular to the reference plane. This step is performed when it is necessary to newly install the bottom blowing tuyere when the use is stopped because the used bottom blowing tuyere is worn out.

  In this process, first, the molten steel and slag in the converter are discharged, and the converter is tilted at an appropriate angle (usually tilted so that the drilling direction is horizontal), and the flange lid 13a. And the presser brick 14a is removed. Thereafter, the flange 100 and a mounting flange of a core drill (not shown) having rotational power to which the core bit 15 is mounted are connected. As a result, the core bit 15 is automatically aligned with the center of the flange 100. Although the accuracy of drilling position and direction is improved by connecting the core drill to the flange 100, if the drilling machine cannot be connected, the converter furnace body and the core drill are positioned and fixed by another method. If possible, the core drill may be arranged on the converter work floor.

  Then, the core bit 15 rotated by the core drill is pushed in a direction perpendicular to the flange surface of the flange 100 and toward the center of the flange 100 to perforate the perforating base brick 7a and the perforating brick 6a. Hole 8 is formed. Instead of the perforating base brick 7a, a base brick 7 in which a hole of a predetermined size is previously installed may be used, and the refractory inserted into the hole may be removed to form the through hole 8.

Here, the core bit 15 for drilling includes a hard segment 16 such as a diamond segment obtained by solidifying diamond abrasive grains at the tip with, for example, a metal bond binder, or a segment made of cemented carbide of tungsten steel, molybdenum steel, or vanadium steel. It is essential that the core bit 15 is provided, and by drilling using the core bit 15, high-speed grinding can be realized without applying mechanical impact force around the through-hole 8.
That is, the core bit with diamond segments has a super hard diamond abrasive bit on the circumference of the segment, so there is no gap between the surrounding refractory bricks when drilling compared to ordinary drilling. Highly accurate drilling is realized. Similarly, a core bit including a cemented carbide segment, for example, a tungsten steel segment obtained by consolidating tungsten carbide (WC) powder with cobalt or nickel, can be drilled with high accuracy because the segment itself is superhard. .

  The core bit 15 may be formed integrally or may be a system in which a plurality of metal tubes are connected with screws, but the ratio of the total length to the outer diameter (total length / outer diameter) is set to 20 or less. The rigidity of the core bit 15 can be sufficiently increased, and drilling with high directional accuracy is possible.

Further, as shown in FIG. 3, cooling water 18 is supplied to the tip of the core bit 15 via the rotating shaft 17 of the core drill. As a result, even when drilling in a high-temperature brick, drilling can be performed at high speed while suppressing the consumption of the diamond segment 16 and the cost of the core bit. The cooling water 18 also serves to ensure lubrication of the core bit by discharging brick grinding waste from the cylindrical grinding groove. Therefore, the amount of cooling water is adjusted according to the situation to the extent that it is discharged in liquid form from the entrance of the core bit on the front side of the grinding groove. When the grinding groove penetrates, the cooling water flows into the inside of the furnace instead of the front side, so that the penetration can be detected.
Here, it is important that the cooling water is discharged in liquid form from the entrance of the core bit on the near side of the grinding groove during drilling. If it is not discharged in the liquid state, the lubrication of the core bit becomes insufficient and the vibration of the core bit is large. As a result, the construction accuracy may deteriorate. Therefore, it is preferable to secure a supply amount such that the cooling water is discharged in liquid form from the inlet of the core bit on the near side of the grinding groove during drilling.

  When the predetermined drilling process is completed, the state of the drill hole is confirmed, the core drill is removed from the flange 100, and the gas blowing pipe 3a and the outer periphery of this pipe are placed in the through hole 8 as shown in FIG. A new bottom-blown tuyere 1a formed by integrally molding the covering tuyere brick 4a into a cylindrical shape is inserted. As the new bottom blown tuyere 1a, it is preferable to use one formed by integrally pressing a plurality of gas blowing pipes 3a and tuyere bricks 4a. Thereby, the gas flow rate fall by the closing of a tuyere can be prevented, suppressing the gas consumption at the time of non-blowing. However, the bottom blowing tuyere is not limited to the one having such a structure, and may be provided with, for example, one gas introduction pipe and a covered refractory covering the gas introduction pipe.

  Here, the gap between the inner surface of the through hole 8 and the outer surface of the new bottom blowing tuyere 1a is 2 mm or less, more preferably 1 mm or less. That is, when this gap becomes larger than 2 mm, there is a problem that the wear rate of a new bottom blowing tuyere increases. By adopting the drilling method as described above, high drilling accuracy is ensured, and the gap can be controlled to about 1 mm or less. When a new bottom blowing tuyere 1a is inserted into the through-hole 8, refractory mortar is applied to the outer surface. As a result, the gap is filled with refractory mortar to some extent, and there is no deterioration in the durability of the new bottom blowing tuyere due to the gap. If conditions such as work time are acceptable, mortar may be pressed into the gap after inserting a new bottom blowing tuyere 1a.

After inserting the new bottom blown tuyere 1a, as shown in FIG. 2 (d), the tuyere presser brick 14 is inserted through the gas introduction pipe 5, and then the tuyere presser flange lid 13 and the furnace bottom flange 100 are shown. Do not fasten with bolts. In order to facilitate replacement when a member such as a screw hole for connecting the core drill is damaged, the core drill or the flange lid 13a may be connected to the flange 100 via an intermediate flange. good.
Thereafter, the gas introduction pipe 5 is connected to a pipe from a gas supply facility (not shown) so that gas can be blown from a new bottom blowing tuyere 1a. Furthermore, the work bricks of the entire furnace including the new bottom blowing tuyere 1a are preheated over several hours by supplying coke into the furnace and supplying top blowing oxygen, and then molten steel as a converter. Used for refining process.

  Further, the perforating brick 6a is a magnesia carbon brick containing 15 to 25% by mass of carbon and further containing 0.5 to 3% by mass of metallic aluminum and 0.1 to 1% by mass of metallic silicon. There is a need. That is, if the carbon content is less than 15% by mass, the thermal shock resistance is lowered, and the portion rapidly cooled by the cooling water 18 at the time of drilling is damaged, so that the wear rate of the new bottom blowing tuyere 1a increases. . On the other hand, when the carbon content exceeds 25% by mass, the oxidation resistance decreases and the erosion rate by the molten iron also increases. As the carbon source, carbon black, pitch and the like can be used in addition to various graphites.

  Further, when the metal aluminum content is less than 0.5% by mass, the high-temperature strength is lowered, so that the wear rate of the perforating brick 6a and the new bottom blowing tuyere 1a is increased. On the other hand, if the amount of metallic aluminum exceeds 3% by mass, it is not effective in reducing the wear rate, and the amount of aluminum carbide produced becomes excessive, so that it is easily damaged by reaction with the cooling water 18 during drilling, The wear rate of the new bottom blowing tuyere 1a increases. Therefore, the metal aluminum content is set to 0.5 to 3% by mass. As a metal aluminum source, Al-Si alloy powder described later can be used in addition to metal aluminum powder.

When metal silicon is added together with metal aluminum, the reactivity of the generated carbide (Al ₄ SiC ₄ ) with water is lower than that of aluminum carbide (Al ₄ C ₃ ), so that reaction with cooling water 18 during drilling is performed. It is possible to suppress damage to the perforating brick 6a. If the metal silicon content is less than 0.1% by mass, the effect of suppressing the formation of aluminum carbide is not sufficient, so that the wear rate of the new bottom blowing tuyere 1a is sufficiently increased due to the reaction with the cooling water 18 during drilling. Cannot be suppressed. On the other hand, even if the metal silicon content is increased from 1% by mass, the effect of suppressing wear is not improved, but rather the corrosion resistance tends to decrease. Therefore, the metal silicon content is 0.1 to 1% by mass. As the metal silicon source, in addition to the metal silicon powder, Al-Si alloy powder is used in the form of Al-Si alloy powder, and the same effect can be obtained even when silicon having the same mass is added.

  Further, the mass ratio of the metal silicon content to the metal aluminum content (metal silicon mass / metal aluminum mass) is desirably in the range of 0.1 to 0.4. This is because if the ratio is less than 0.1, an increase in the wear rate of the new bottom blowing tuyere 1a due to the influence of the reaction with the cooling water 18 during drilling cannot be sufficiently suppressed. On the other hand, even if it exceeds 0.4, the wear suppression effect does not improve further, but rather the corrosion resistance tends to decrease.

  In addition, boron etc. can be added as components other than the said component of the brick 6a for a hole, and the remainder is magnesia.

  If the perforating brick is perforated after the temperature of the brick is lowered, there is a possibility that the range of influence by the cooling water 18 during perforation is expanded and the wear rate of the new bottom blowing tuyere 1a is increased. For this reason, after finishing the last converter blowing before drilling, it is desirable to carry out as soon as possible, and it is desirable to carry out within 20 hours at the latest. This is because if it exceeds 20 hours, the brick is cooled and the thermal expansion is stopped, joint opening around the construction occurs, and the water for bit cooling flows out of the perforation range, and the brick of the furnace body is damaged. This is because there is a risk.

Further, as a temperature condition of the perforating brick, it is desirable to start perforating while the average temperature of the perforating base brick is 500 ° C. or higher. This is because when the temperature is lower than 500 ° C., water for cooling the bit flows out of the perforation range, and the brick of the furnace body may be damaged.
Normally, even when several bottom-blown tuyere are newly installed, the drilling can be carried out within about 6 hours from the end of the final converter blowing, and the average temperature of the drilling brick is 650 ° C or higher. Can start.

  In this way, a predetermined drilling direction is provided at the center of the drilling brick 6a without causing damage to the drilling brick 6a or the surrounding work brick 12 or causing the through-hole 8 to become larger than necessary. If the through-hole 8 is formed by drilling in a short time along the bottom, the bottom blowing tuyere can be reliably installed in the hot. As a result, the wear rate of the new bottom blowing tuyere is equivalent to the wear rate of the bottom blowing tuyere that has been used since the operation of the converter, and the appropriate number of bottom blowing tuyere is secured until the end of the furnace life. The refining reaction of the furnace is made efficient until the end of the life of the furnace body, and improvement in converter productivity is achieved, such as improvement in iron yield and reduction in iron alloy basic unit.

In addition, this invention is not limited to the above place, A various change is possible. For example, although the base brick 7 is installed, the base brick 7 may not be installed, and the drilling brick 6a serving as the tuyere receiving brick may be arranged in contact with the flange lid 13, or a plurality of layers of work Brick 12 may be arranged. Furthermore, although an example of a bottom blowing tuyere in which a plurality of metal thin tubes for injecting a stirring gas such as Ar gas or N ₂ gas has been described, the present invention is not limited to this, and a single tuyere tuyere or O ₂ The present invention is also applicable to a double tube tuyere for blowing gas and cooling gas. In the case of a single tube tuyere, it is desirable to form a new bottom-blown tuyere by inserting it into the through-hole 8 together with tuyere bricks that cover it. It is desirable to insert the heavy pipe directly into the through hole 8 and fill the gap with refractory mortar. Thereby, the thermal stress generated in the tuyere brick near the tip of the outer surface of the double pipe that is strongly cooled can be relieved and the tuyere life can be improved.

About the hot installation method of the converter bottom blowing tuyeres concerning this invention, it implemented in the 350t scale converter, and performed various evaluation. The molten iron discharged from the blast furnace and a scrap of about 10% by mass with respect to the molten iron are charged into the converter, and argon gas or nitrogen gas is added to the bottom blowing tuyere shown in FIG. Decarburization blowing was repeatedly performed while blowing at 15 Nm ³ / min · t. At that time, using a laser profile measuring device, the remaining thickness of each tuyere was measured intermittently across the number of blows of several hundred charges, the wear rate was evaluated, and the life of the tuyere was determined.

  When the remaining thickness of the tuyere reaches a predetermined value (100 mm from the surface of the permanent brick), the use of the tuyere is stopped and the worn part is repaired with an irregular refractory, and the above-described FIGS. In accordance with the method for hot installation of bottom blowing tuyeres according to the present invention, new bottom blowing tuyere were installed on the six drilling bricks 6a previously installed on the furnace bottom. That is, after the use of the tuyere was stopped and preparatory work was performed, drilling was started 2-3 hours after the end of the last final blowing. The average temperature of the perforated brick at that time was 700 ° C. or higher in any case according to the measured surface temperature and the heat transfer calculation result. Several types of drilling bricks with different materials were prepared.

  Next, after installing six tuyere hot, coke was put into the furnace, oxygen was blown up to preheat the furnace, and then decarburization blowing was repeated in the same manner as described above. . Table 1 shows the composition of the drilling bricks used and the wear rate of the tuyere installed hot. As a reference example, the composition of the tuyere block brick 6 of the tuyere installed in the initial stage and the wear rate of the tuyere installed in the initial stage are also shown.

Comparing the inventive example and the reference example, it can be seen that the wear rate of the tuyere installed hot by the method of the present invention is equivalent to the wear rate of the tuyere installed in the initial stage. On the other hand, in Comparative Example 1 using a perforating brick that does not contain metallic silicon, the wear rate is significantly increased as compared with the inventive example.
Here, from the comparison between Comparative Example 1 and Reference Example 2, in this material, the wear rate of the tuyere installed hot is greatly increased compared to the wear rate of the tuyere installed initially, This indicates that this brick material is easily damaged by the influence of cooling water during drilling. Reference Example 3 is an example of a material that is hardly affected by the cooling water and has a reduced metal aluminum content. However, since the high-temperature strength is reduced, the wear rate is high even in the tuyere installed at the initial stage.
Incidentally, in the inventive examples, Invention Examples 1 to 3 and 5 to 8 in which the metal Si / metal Al is 0.1 to 0.4 have a lower tuyere wear rate than the Invention Example 4.

Further, in Comparative Example 2 in which the carbon content of the perforated brick was low, Comparative Example 3 in which the amount of metallic Al was low, and Comparative Example 4 in which the amount of metallic Al was large, the wear rate increased. Furthermore, in Comparative Example 5 having a large amount of metallic Si, the wear rate increased because the hot strength was low.
Further, in Comparative Example 6 in which construction was performed without water supply, the vibration of the bit increased during drilling, the gap between the drilled through hole and the newly installed tuyere brick increased, and the wear rate increased. In Comparative Example 7 in which carbon steel was used for the core bit segment, the wear rate of the tuyere increased because a gap occurred in the surrounding refractory bricks during drilling. In Comparative Example 8, after the tuyere was installed, the wear rate of the newly installed bricks around the tuyere increased, and the wear rate of the tuyere increased.

  As described above, according to the hot installation method of the bottom blow tuyere of the present invention, the center portion of the drilling brick is shortened along a predetermined drilling direction while ensuring the durability of the drilling tool by water cooling. It is possible to prevent the life of the tuyere receiving bricks perforated from the tuyere bricks and the perforating bricks installed after the drilling from being drilled with precision with time to form through holes. In the above description, the case where all of the six bottom blowing tuyere are switched at a time has been shown. However, since the tuyere can be installed in a relatively short time in the method of the present invention, 1 A method may be used in which one tuyere is added and installed each time.

  According to the present invention, the bottom blowing blade is formed by drilling a through hole in a short time along a predetermined drilling direction in the center of the drilling brick without damaging the drilling brick and the peripheral work brick. The mouth can be installed hot, and the life of the tuyere installed hot can be prevented. As a result, the operating rate of the converter can be improved while reducing the cost of refractories, and the bottom blowing tuyere can be kept healthy throughout the operating period of the converter, improving the converter productivity and the iron yield. Industrial value such as improvement is high.

DESCRIPTION OF SYMBOLS 1 Bottom blowing tuyere 1a Bottom blowing tuyere for hot installation 2 Wind box 2a Wind box for bottom blowing tuyere for hot installation 3 Gas blowing pipe 4 Tuyere brick 5 Gas inlet pipe 6 Tuyere block brick 6a For drilling Brick 7 Base brick 7a Base brick for drilling 8 Through hole formed in brick for drilling 10 Iron skin
100 flange 11 permanent brick 12 work brick 13 tuyere presser flange lid 13a flange lid 14 tuyere presser brick 14a presser brick 15 core bit 16 diamond segment 17 core drill rotating shaft 18 cooling water

Claims (3)

In the refractory layer covering the bottom of the converter, a drilling brick is previously placed in a portion other than the installation site of the bottom blowing tuyere, and a new bottom blowing tuyere is added to the drilling brick after the use of the converter. When installing
As the perforating brick, a magnesia carbon brick containing metal aluminum: 0.5-3 mass%, metal silicon: 0.1-1 mass% and carbon: 15-25 mass% is arranged, from the outside of the bottom. With respect to the drilling brick, the core bit having a hard segment is drilled while supplying water to the tip of the core bit to form a hole penetrating the refractory layer in the drilling brick. A method for hot installation of a converter bottom blowing tuyere characterized by inserting a new converter bottom blowing tuyere.   The method for hot installation of a converter bottom blowing tuyere according to claim 1, wherein the drilling of the brick for drilling is performed within 20 hours from the end of the last blowing in the converter before the drilling.   The method for hot installation of a converter bottom blowing tuyeres according to claim 1 or 2, wherein the temperature at the start of drilling of the brick for drilling is 500 ° C or higher.

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