JP2011001621A - Method for repairing furnace-bottom refractory in converter having bottom-blowing function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To repair a local worn part extending in the wide range at a furnace-bottom part in a converter having a bottom-blowing function by high quality lining having uniform and sufficient thickness and excellent durability, at quicker time in comparison with the conventional method.SOLUTION: This repairing method includes: a process in which slurry is obtained by kneading a repairing raw material for furnace bottom refractory and a resin demonstrating a self-hardening with the chemical reaction; a process in which the whole local worn part is covered with the slurry by charging the slurry toward the local worn part extending in the wide range at the furnace bottom part in the converter from the furnace opening part; and a process in which the slurry covering the whole worn position is hardened with the chemical reaction generated in the slurry.

Description

  The present invention relates to a furnace bottom refractory repairing method for a converter having a bottom blowing function.

  In general, in a converter having a bottom blowing function, in order to blow gas from the bottom of the furnace, the bottom blowing tuyere and the like by repeated stirring and heating of the refractory lining and cooling of the inner refractory, etc. It is well known that the furnace bottom brick cracks and peels, and the center of the furnace bottom, including the bottom blowing tuyeres, is locally worn compared to the area around the furnace bottom. Various countermeasures have been disclosed as countermeasures.

  For example, Patent Document 1 discloses a repair method using a refractory for repairing a baking material. However, in this method, since the refractory is cured by using the residual heat of the converter after the operation is stopped, the converter brick needs to have a temperature of 900 ° C. or more, and if the repair construction body is thick, the inside of the construction body There was a problem that it was difficult to ensure the quality of the construction body due to the poor heat transfer and the lack of volatile content from the construction body, making it difficult to repair.

  Patent Document 2 discloses a method in which the tuyere tip is protected for the purpose of preventing clogging of the tuyere, and then the spray repair is performed from the operating surface. There was a problem that it was difficult to quickly restore a wide range of damaged parts with a sufficient thickness because the amount of repair materials that could be applied per hit was small.

  Patent Document 3 discloses a method of applying a press-fit material into the furnace from a dedicated hole provided in the bottom of the converter furnace by using press-fit repair. However, in this method, prevention of explosion of the press-fit repair material is disclosed. Therefore, there is a problem that furnace cooling time is required, and it is difficult to perform uniform construction over a wide area because the material is supplied from the back side.

  Patent Document 4 discloses a method of coating the bottom of a furnace after modifying the furnace while leaving the slag in the furnace. However, in this method, since the slag is used, there is a drawback that the durability of the repair construction body is short. .

  Patent Document 5 discloses a method of rebuilding the furnace bottom, but in this method, the furnace is cooled and a furnace tower is installed in the converter, and it is necessary to build by building bricks, which takes time. There was a problem of lowering the operating rate.

  In addition, a technique for exchanging the furnace bottom is known as a structure that allows the furnace bottom to be exchanged in advance. For example, Patent Document 6 proposes shortening the construction period using various machines. However, even in the method of exchanging the furnace bottom, since it takes the furnace cooling process, the furnace bottom removing process, the attaching process, and the temperature raising process, it takes, for example, a long time of 48 hours or more, and the operation rate of the converter is lowered. It became.

JP-A-9-61061 JP 59-129711 JP 63-216945 JP 63-149310 JP 59-200710 JP 11-350016 A

  The object of the present invention is to solve the above-mentioned problem, and to provide a sufficient lining thickness equivalent to the surrounding refractory remaining for a wide range of local wear parts of the bottom of the converter furnace having a bottom blowing function. In addition, the present invention provides a technique for performing refractory repair that has a superior resistance to repair materials more quickly than in the past.

  The furnace bottom refractory repairing method for a converter having a bottom blowing function of the present invention, which has been made to solve the above-mentioned problems, includes a step of replacing the bottom blowing nozzle, and a chemical reaction with a raw material for repairing the bottom bottom refractory. A step of kneading a resin exhibiting hardness to obtain a slurry, and introducing the slurry from a converter furnace port toward a locally worn part over a wide range of the bottom of the converter furnace, and covering the entire locally worn part with the slurry. And a step of curing the slurry covering the entire portion of the locally worn portion by a chemical reaction generated in the slurry.

  A second aspect of the present invention is the method of repairing a bottom refractory of a converter according to the first aspect, wherein the slurry is mainly composed of magnesia formed by adding an acid or a catalyst used for curing the resol type phenol resin. It is obtained by kneading a solid powder raw material, a resol type phenolic resin, and a binder solution containing the solvent as a main component.

  The invention according to claim 3 is the method of repairing a bottom refractory for a converter according to claim 2, wherein the slurry contains calcia, alumina, silica and a composite oxide thereof in the solid powder raw material. To do.

  The invention according to claim 4 is the furnace bottom refractory repair method according to claim 1, wherein the temperature of the converter refractory brick is 400 ° C. or higher and 900 ° C. or lower, and the slurry is fed from the converter furnace port to the converter furnace. It throws in toward the local wear spot of a bottom part, It is characterized by the above-mentioned.

  The invention according to claim 5 is the furnace bottom refractory repairing method according to claim 1, wherein the amount of the slurry to be charged is 4 to 25 tons.

  A sixth aspect of the present invention is the furnace bottom refractory repairing method according to the first aspect of the present invention, wherein the slurry is introduced from the central position of the converter furnace port.

  In the furnace bottom refractory repair method according to claims 1 to 3 of the present application, the slurry, which is a non-aqueous refractory repair material, is introduced into the local wear spot of the furnace bottom, so that the metal carbide contained in the brick reacts with water. There is no. For this reason, collapse due to expansion of the brick does not occur, and the soundness of the brick is not impaired. In addition, since the slurry, which is a self-hardening refractory repair material, is put into the local wear spot at the bottom of the furnace, even if the temperature of the converter brick decreases after the operation is stopped, the residual heat of the low-temperature converter brick is used. The refractory repair material can be cured in a short time.

  In the furnace refractory repair method according to claim 4 of the present application, the converter brick is charged at a temperature of 400 ° C. or more and 900 ° C. or less, so that the residual heat of the converter brick in the temperature range is used for a short time. Can harden the refractory.

  In the furnace refractory repairing method according to claim 5 of the present application, the amount of the slurry to be charged is 4 to 25 tons, so that it can be repaired even if the furnace bottom local wear spot is wide.

  In the furnace bottom refractory repairing method according to claim 6 of the present invention, since the slurry is introduced from the central position of the converter furnace port, it is possible to evenly repair the locally worn portion of the furnace bottom, and the refractory repairing material is obtained after the slurry is cured. There is no uneven distribution.

It is explanatory drawing of the furnace bottom refractory repair method of this invention. It is data which shows the relationship between the converter operation frequency and a refractory residual index. It is a converter furnace bottom profile before and after repair implementation of this invention.

  In FIG. 1, the explanatory view of the furnace bottom refractory repairing method of the present invention is shown.

  The furnace bottom refractory repairing method for a converter having a bottom blowing function of the present invention includes a step of replacing the bottom blowing nozzle, and a kneaded resin that exhibits self-hardness by a chemical reaction with a material for repairing the bottom refractory. A step of obtaining a slurry, a step of charging the slurry from the converter furnace port toward a local wear area over a wide area of the bottom of the converter furnace, covering the entire local wear area with the slurry, and the entire local wear area The covered slurry has a process of hardening by a chemical reaction generated in the slurry. Hereinafter, each step will be described in detail.

(Process to replace the bottom blowing nozzle)
Since the bottom blowing nozzle wears out in the same way as the brick around the nozzle, when the furnace bottom refractory repair method of the present application is carried out without replacing the nozzle, the nozzle opening becomes thick due to the refractory repair material after hardening the slurry. It is covered and obstructed, and gas cannot be blown in. For this reason, the bottom blowing nozzle is replaced before the slurry is introduced from the converter furnace port, and the refractory repair material is prevented from covering the nozzle port. If the thickness of the repaired part with the repair material is adjusted so that it is equal to the height of the nozzle port after replacement, the nozzle port can be used when blowing the bottom blowing gas even if the refractory material is covered to some extent. The occlusion is easily resolved. For this reason, the curing etc. which prevent that a nozzle mouth is obstruct | occluded when replacing | exchanging a nozzle are unnecessary.

(Process to obtain slurry by kneading resin that exhibits self-hardness by chemical reaction with repair material for furnace bottom refractory)
The plurality of raw materials constituting the refractory repair material are classified into solid powder raw materials (hereinafter referred to as powder raw materials) and liquid raw materials (hereinafter referred to as liquid raw materials). The powder raw material is mainly composed of magnesia having fire resistance, and contains calcia, alumina, silica, and composite oxides thereof having the same fire resistance, carbon, and other impurities contained in these raw materials. The powder raw material is a particle having a diameter of 5 mm or less for fluidity expression, but a coarse particle having a particle diameter of 30 mm or less made of magnesia, calcia, alumina, silica, and composite oxides having fire resistance to improve corrosion resistance May be added in an amount of 18% by mass or less of the whole powder raw material. If added more than this, the fluidity of the slurry may be impaired. On the other hand, the liquid raw material is added with a binder solution mainly composed of a resol type phenol resin and a solvent thereof, and a curing acid catalyst, a curing accelerator, a curing retarder, and a degassing accelerator as necessary.

  The powder raw material is uniformly mixed at the stage of production in advance. The acid or catalyst used for curing may be prepared separately and added when mixing the powder raw material, the resin, and the solvent solution.

  When the plurality of raw materials are combined and kneaded with a mixer, the resol-type phenol resin undergoes dehydration and condensation reactions by the action of an acid or a catalyst, forms a crosslinked body after a certain reaction time, and develops strength.

  It is preferable to contain a large amount of basic refractory aggregates such as magnesia and calcia because the fire resistance and corrosion resistance are better. Specifically, it is preferable to contain 50% by mass or more of magnesia in the powder raw material. If the ratio of the phenol resin and the solvent added to the powder raw material is too large, it is not preferable from the viewpoint of fire resistance, but if it is too small, the fluidity is impaired. Therefore, 6-24 mass% is preferable with respect to the whole slurry.

  The kneading is performed at 200 to 2000 kg / batch, and the environmental temperature at the time of kneading is about 40 ° C. at the maximum.

  The properties of the slurry obtained as a result of kneading are evaluated by the flow value. The flow value is the diameter of the circle in which the mortar flow cone (φ70mm × φ100mm × 60mm flow measurement cone based on JIS R 5201) is filled with the material, the cone is pulled upward, and the kneaded material naturally flows and spreads. is there. When a squeeze pump is used, a flow value of 200 mm or more is required. When a piston pump is used, a flow value of 130 mm or more is required. The flow value is a kneading condition such as a mixer blade rotation speed, a kneading time, a particle size configuration, and a solvent addition ratio. Adjust by blending materials such as.

(Step of supplying the slurry from the converter furnace port toward the local wear spot over a wide area at the bottom of the converter furnace, and covering the entire local wear spot with the slurry)
As shown in FIG. 1, the slurry is charged from a converter furnace port 1 toward a local wear spot 2 over a wide area at the bottom of the converter furnace. As a result, the charging means only needs to reach the local wear point 2 where the repair material is present. For example, it is desirable to pass a pumping piping port connected to the pumping machine 4 to the center of the converter furnace port 1 and to add slurry from the position. In addition, the slurry may be thrown into the pressure feeder 4 by dropping a heat-resistant hose to the furnace bottom repair site. Furthermore, it is desirable to move the pressure feed piping port and the heat-resistant hose port as appropriate according to the wear shape of the local wear spot 2 and to uniformly introduce the slurry.

  It is desirable to add an amount of slurry according to the volume to be repaired by quantitatively grasping the range and depth of the local wear spot 2 with a laser distance meter or the like. Specifically, according to the present invention, the amount of slurry to be charged is preferably 4 to 25 tons. If the amount of slurry input is less than 4 tons, the conventional spray repair method is sufficient, and if the repair method of the present application is implemented, the cost and time involved in repair will be excessive despite the small-scale repair. . Moreover, if it is the local wear part 2 of a general converter, it can fully repair with the slurry amount of 25 tons or less. For example, by introducing 15 tons of slurry, the bottom of a 300 ton converter with a molten steel weight can be increased by 1000 mm and repaired. Here, the amount of increase in thickness = the weight of slurry added / the specific gravity of the repair material × the area of the locally damaged portion of the furnace bottom.

(The process in which the slurry covering the entire local wear spot is cured by a chemical reaction occurring in the slurry)
The chemical reaction of the present invention refers to a reaction in which a resol type phenol resin undergoes dehydration and condensation reactions by the action of an acid or a catalyst to form a crosslinked body after a certain reaction time and develop strength.

  In the present invention, “cured” means that the slurry does not flow, for example, the material flows even if the frame is turned over after being applied to a test metal frame of 40 mm × 40 mm × 160 mm and left for a predetermined time. Means not to go out of the frame. In order for the slurry to be cured efficiently, it is desirable to feed the slurry at a converter brick temperature of 400 ° C to 900 ° C. When it is introduced at a temperature lower than 400 ° C., the time until the slurry is hardened is about twice as long as the above temperature range, so the repair time becomes longer, and when it is introduced at a temperature exceeding 900 ° C., In addition to increasing the pores in the object and reducing the corrosion resistance, the possibility of explosion is increased.

  As described above, the furnace bottom refractory repair method of the converter of the present invention is a slurry-type refractory repair material having an appropriate flow value, and a large amount of refractory repair material is charged from the converter furnace port, and the converter after the operation is stopped. The residual heat of the brick can be hardened in a short time to repair the refractory material worn over a wide area thickly and evenly. For this reason, the repair method is an extremely effective repair method for a converter, which is a main equipment in a steelmaking process that requires high operation efficiency and a large amount of molten steel processing.

  Regarding the converter with a molten steel weight of 268 tons, the bottom of the furnace bottom was predicted to be about 3000 ch from the wear rate of the bottom of the tuyere at the stage where the bottom of the furnace was extremely worn and 2000 ch was used. On the other hand, the side wall was in a worn state where the durability of about 4000 ch was predicted. Therefore, it was decided to repair the furnace bottom. A device as shown in FIG. 1 was used for the repair. The repair material raw material contains 70% by mass of magnesia, other phenol resin curing catalyst, etc., and the powder raw material having a particle size of 3 mm or less, and the liquid raw material are composed of a resol type phenol resin and a polyhydric alcohol as a solvent thereof. A resin binder solution was used. The kneading was performed at a ratio of the liquid raw material 1 to the powder raw material 4.

  After the converter was stopped and the work was prepared, the bottom blowing nozzle at the bottom of the furnace was first replaced. Subsequently, the powder raw material and the liquid raw material were kneaded with two mixers having a rated kneading amount of 250 kg installed on the top floor of the converter furnace, and a kneaded material having a flow value of 220 mm was obtained. The piping for pressure feeding was passed from the mini cleat to the center of the converter furnace port, through which the slurry was pumped and put into the converter furnace. Start feeding from the center of the converter furnace so that the slurry spreads over the entire area of local wear at the bottom of the converter furnace, and confirms the flow of the slurry using a monitor camera and confirms the monitor image with a monitor image. It was thrown in while adjusting the position of the mouth. The temperature of the converter brick when the slurry was charged was 550 ° C. as a result of measurement with a radiation thermometer or the like. The amount of slurry charged was 15 tons, covering the entire area of the local wear area of the furnace bottom. After the slurry was cured, the converter was heated up and restarted. With the implementation of the repair method according to the present invention, the time from the operation stop to the operation restart is 21 hours, which is about ½ of the time spent for the conventional repair method. The breakdown of 21 hours was 12 hours for preparation and replacement of the bottom blowing nozzle, 4 hours for kneading the repair material, and 4 hours for charging the slurry, and 5 hours for curing the charged slurry.

The result of measuring the profile of the converter furnace bottom before and after the repair using a laser distance meter is shown in FIG.
Further, the subsequent wear state of the furnace bottom is shown in FIG. As shown in FIG. 2, a life extension effect of at least about 700 ch (arrow in the figure) is recognized by this repair method.

DESCRIPTION OF SYMBOLS 1 Converter furnace opening 2 Local wear part 3 Pumping piping 4 Pumping machine 5 Kneading machine 6 Converter main body 7 Furnace top hood

Claims (6)

A step of exchanging the bottom blowing nozzle, a step of kneading a resin that exhibits self-hardness by chemical reaction with a repair material of the furnace bottom refractory, and obtaining a slurry; and the slurry from the converter furnace port to the bottom of the converter furnace A step of covering the entire area of the local wear area with the slurry, and a step of curing the slurry covering the entire area of the local wear area by a chemical reaction generated in the slurry; A furnace bottom refractory repairing method for a converter having a bottom blowing function. The slurry includes a solid powdery raw material mainly composed of magnesia to which an acid or a catalyst used for curing the resol type phenol resin is added, a resol type phenol resin, and a binder solution mainly composed of the solvent. The furnace bottom refractory repairing method for a converter having a bottom blowing function according to claim 1, wherein the furnace bottom refractory repairing method is obtained. 3. The method of repairing a bottom refractory for a converter having a bottom blowing function according to claim 2, wherein the slurry contains calcia, alumina, silica and a composite oxide thereof in a solid powder raw material. The bottom blowing function according to claim 1, wherein the converter refractory brick has a temperature of 400 ° C. or more and 900 ° C. or less, and the slurry is charged from a converter furnace port toward a locally worn portion at the bottom of the converter furnace. A method for repairing the bottom refractory of a converter. The method for repairing a bottom refractory for a converter having a bottom blowing function according to claim 1, wherein the amount of the slurry to be added is 4 to 25 tons. 2. The method of repairing a furnace bottom refractory for a converter having a bottom blowing function according to claim 1, wherein the slurry is charged from a central position of the converter furnace port.