KR100315372B1 - A coating composition for the internal wall of converter and its preparations, and coating method using it - Google Patents

Abstract

PURPOSE: A composition for coating the inner wall of a converter which comprises high purity MgO and limestone containing a lot of CaCO3, is provided to lengthen lifetime of inner wall. CONSTITUTION: The composition of coating materials is as follows; 70-84wt.% of high purity MgO comprising 95.33-96.86wt.% of MgO, 0.60-0.67wt.% of SiO2, 0.12-0.19wt.% of Al2O3 and 2.42-3.81wt.% of CaO; and 16-30wt.% of limestone comprising 95.25-97.65wt.% of CaCO3, 1.0-1.5wt.% of SiO2, 0.25-0.75wt.% of Al2O3, 1.0-2.0wt.% of MgO and 0.1-0.5wt.% of Fe2O3. The coating materials are produced by grinding the composition to 90-130mesh, adding 15-25wt.% of water to the ground composition and mixing, forming it into an almond shape, and drying it at 20-30deg.C to be a compressive strength of 10-20kg/cm¬2. The inner wall is coated by filling the inner wall of converter(900-1200deg.C) with the produced coating materials, and ejecting N2 gas under a pressure of 10-20kg/cm¬2 for dispersing of the coating materials, and air-cooling them.

Description

A coating composition for the internal wall of converter and its preparations, and coating method using it}

The present invention is to coat the inner wall of the converter (Converter) to be refined by using the heat to remove the impurities by oxidative combustion by removing oxygen gas or the like to the inside or surface of the molten pig iron in the furnace. The present invention relates to a converter inner wall coating material composition and a method of manufacturing the same, and a converter inner wall coating method using the same.

For example, the converter method blows and removes carbon (C) by blowing high-pressure air, that is, oxygen (O ₂ ) into the molten steel, and removes phosphorous and sulfur, which are harmful components in the molten metal, as well as controls steel components to clean steel. The inner walls of conventional converters are constructed of Dolomite Brick, which is vulnerable to oxidative erosion, and when using such converters made of Dolomite brick, they use only a few hundred charges (Charge). It has caused huge obstacles to economics and productivity.

Therefore, in order to solve the above problems, in recent years, the inner wall of the converter is made of magnesium oxide-carbon brick (MgO-C Brick), which has a stronger oxidation erosion than the dolomite brick, thereby extending the number of uses of the converter by more than 1000.

However, since MgO-C Brick also blows oxygen, there is a limit to extending the service life of the converter to thousands of charges depending on its non-wetting property, which is its physical property.

Therefore, the oxidation prevention technology of MgO-C Brick for the extension of the service life of the converter has been studied and the Vessel tilt slag coating method has been attempted and is widely used. It uses a method of splashing slag with gas and coating it, which is the nitrogen device, the MgO component and the viscosity of the slag, as well as the management of additives and operating conditions. Conditions must be well coordinated and maintained to extend converter life.

The splashing was examined as a nitrogen device and the MgO was examined as light MgO (light spherical), but there was light dolomite, raw dolomite, limestone, etc., but slag splashing with nitrogen was performed to MgO-C Brick. The prolongation of lifespan conditions involve numerous problems.

First, MgO component should be saturated (more than 8wt%) in slag in a short time. For small dolomite, MgO content is 35wt%-40wt%, and MgO purity is low and fluidity is increased at 45wt%-50wt% CaO. This is because the CaO component is high (small sphere: MgO 70wt%-74wt%). Second, there is a dose problem to control the MgO component early (small sphere: 1Ton, small dolomite: 2Ton).

Third, when small dolomite is used to control the high concentration of slag viscosity by increasing the MgO component, increasing the input amount to increase the MgO component increases the CaO content, which additionally increases the fluidity.

And if the CaO content is excessive, the phosphorus (P) component reduction is accompanied by a difficult problem.

Fourthly, when using other MgO raw materials other than light bulbs, it must be processed into powder (lump) in powder form.

Fifth, as in the light bulb, the 'sphere' is instantaneously destroyed and dissipated by heat and temperature in the converter, and thus there is a lack of advantages of early diffusion and reaching the appropriate viscosity of slag caking state.

Sixth, when raw dolomite is used, it takes time to decompose the dolomite, and since it is a raw material, the temperature in the furnace is lowered, so that it is not easy to reach the optimum viscosity, and the amount of MgO is low (19-21%) Even if other adverse conditions are taken into account, there is a problem in adjusting the slag viscosity because the CaO content is excessively added.

The present invention has been made to solve the problems of the prior art as described above, the object of the present invention is to adjust the basicity of the slag by adding a certain amount of mild magnesia during the steelmaking of the converter and the MgO of the inner wall of the converter due to the slag The present invention provides a converter inner wall coating material composition and a method of manufacturing the same, and a method of coating a converter inner wall using the same, which minimizes component erosion and protects the inner wall of the converter, thereby easily extending the service life of the converter. In the converter inner wall coating composition, MgO 95.33wt%-96.86wt%, SiO ₂ 0.60wt%-0.67wt%, Al ₂ O ₃ 0.12wt% remaining after thermally decomposing CO ₂ by heat-treating magnesite containing MgCO ₃ High purity MgO 70 wt%-84 wt% consisting of a composition ratio of 0.19 wt% and 2.42 wt%-3.81 wt%; CaCO ₃ 95.25wt%-97.65wt%, SiO ₂ 1.0wt%-1.5wt%, Al ₂ O ₃ 0.25wt%-0.75wt%, MgO 1.0wt%-2.0wt% and Fe ₂ O ₃ 0.1wt%-0.5 16wt% containing CaCO ₃ consisting of a composition ratio of the wt% of limestone - provides the converter inner wall coating composition is a mixed composition with 30wt% in another aspect, the present invention in preparing the converter inner wall coating, 900 ℃ the MaCO ₃ - 1200 ℃ In the first step, the first step of crushing the high-purity MgO 70wt%-84wt% obtained by thermal decomposition with CO ₂ and 16wt%-30wt% of limestone containing CaCO ₃ with a shredder to 90 mesh-130 mesh In order to give moldability to the fine particles crushed by the second step of adding water of 15wt%-25wt% and mixing it using a mixer, the mixture mixed by the second step in the almond shape using a mold molding and compression strength 10Kg / cm ² - 20 ℃ to be 20Kg / cm ² - made of a third step of drying at 30 ℃ converter Provides a method of making wall coatings Furthermore the present invention highly pure MgO 70wt% -. 84wt% and CaCO ₃ limestone 16wt% containing - according as coated electric furnace inner wall in a 30wt% is mixed dry coating material, the temperature inside the electric furnace A first coating step of filling the interior of the converter in an amount to apply the coating material to the interior of the converter as a whole at 900 ° C-1200 ° C; A second coating step of the spray by 20Kg / cm ² as the pressure the coating material dispersed by the pressure of the nitrogen to be attached to the inner wall of a converter, wherein the first coating step is finished, a nitrogen with an oxygen lance 10Kg / cm ^2; After the second coating process is completed, the coating method of the inner wall of the converter consisting of a third coating step of taking out the oxygen lance from the converter and air-cooled.

1 is a process chart showing a manufacturing method of a coating material composition of an inner wall of a converter according to the present invention;

Figure 2 is a process chart showing a coating method of the inner wall of the converter using the coating material composition according to the present invention,

Figure 3 is a block diagram for explaining a coating method of the inner wall of the converter using the coating material composition of the present invention.

<Code Description of Main Parts of Drawing>

1: converter

1a: inner wall 2: pallet

3: oxygen lance

Hereinafter, the converter inner wall coating material composition according to the present invention and a manufacturing method thereof and preferred embodiments of the coating method of the converter inner wall using the same will be described in detail. First, the coating material composition of the converter inner wall for extending the lifetime of the converter of the present invention will be described. .

The converter inner wall coating composition according to the present invention is made by mixing high purity MgO 70wt%-84wt% and CaCO ₃ containing limestone 16wt%-30wt%. Here, high purity MgO is a magnesiumite containing MgCO ₃ to 900 ℃-1200 ℃ Pyrolysis of CO ₂ by heat treatment results in pyrolysis of CO ₂ resulting in 95.33 wt%-96.86 wt% MgO, i.e. magnesite containing MgCO ₃ (CO ₂ 40 wt%-45 wt% mixed in salt) Is composed of MgCO ₃ 97.55wt%-98.7wt%, SiO ₂ 0.25wt%-0.35wt%, Al ₂ O ₃ 0.05wt%-0.1wt%, CaO 1.0wt%-2.0wt% Pyrolysis of CO ₂ by heat treatment consists of MgO 95.33wt%-96.86wt%, SiO ₂ 0.60wt%-0.67wt%, Al ₂ O ₃ 0.12wt%-0.19wt% and CaO 2.42wt%-3.81wt% will be of high purity MgO is produced limestone containing the CaCO ₃ is _{CaCO 3 95.25wt% -. 97.65wt%} , SiO 2 1.0wt% - 1.5wt%, Al 2 O 3 0.25wt% - 0.75wt%, MgO 1.0wt %-2.0wt%, Fe ₂ O ₃ 0.1wt% It is composed of a composition ratio of 0.5wt%. The method for preparing a coating material using the composition thus prepared is as follows. As shown in FIG. 1, the magnesite containing MgCO ₃ is 900 ° C to 1200 The first step of mixing and grinding 70% to 84wt% of high purity MgO remaining by thermal decomposition at ₂ ° C. and pyrolysis of CO ₂ and 16wt% to 30wt% of limestone containing CaCO ₃ , the second step of adding water and mixing the mixture The coating material is formed by sequentially molding the mixture to which the addition is carried out, followed by the third step of drying, and the crushed crushed product can be commercialized as it is, and the dry coating material can be commercialized. MgO 70wt%-84wt% and high-purity CaO 16wt%-30wt% mixed crushed to prepare a crushed, crushed by a crusher and the like to shred the particle size of 90 mesh-130 mesh. In the first step, water is added to the crushed crushed material and then mixed with a mixer. In the second step, 15 wt% to 25 wt% of water is added to give the moldability to the crushed crushed material. The third step is to mold and dry the mixture mixed in the second step, and the mixture is molded into a mold, but the size of the molding is molded in the length and width of 30 mm to 60 mm, and the molding is preferably formed in the almond shape. And the third step is to transfer the molded product formed in the molding process to a drying plant by using a belt conveyor or the like to naturally dry it, and to dry the molded product to a room temperature of 20 ℃-30 ℃ drying temperature the molded article it is preferable to dry in a 24-hour, where high-purity MgO is obtained by heat-treating the magnesite containing MgCO ₃ is In addition to maintaining the high viscosity of the lag, the saturation of the MgO component in the slag is maintained to prevent erosion by infiltration. Of course, when the MgO contained in the high purity MgO does not reach or exceeds 95.33 wt%-96.86 wt%, the slag It is impossible to prevent the erosion due to maintaining the viscosity of the MgO component and the saturated state of the MgO component in the slag. In the present invention, the limestone containing the high-purity MgO and CaCO ₃ , which are large lumps, is crushed into 90 mesh-130 mesh, If the particle size is larger than the above range, the moldability is poor and the adhesion strength is easily broken, and if the particle size is smaller than the above range, it is scattered and difficult to handle. Of course, the high purity MgO and limestone are 90 mesh-130. After crushing to the size of the mesh, it may be packaged and stored as it is, or sold in the packaged state. In order to give moldability to the mixture of limestone, water is added and then kneaded, wherein the addition ratio of water is 15 wt% to 25 wt% of the total weight of high purity MgO and limestone. If it is less than 15wt%, the moldability is not good, so it is not easy to mold, and if the moisture is more than 25wt%, it becomes too tough to handle even if it is molded.The size of the molding is 30mm to 60mm in length and width. The reason for this is to facilitate handling, and the reason for making the coating material into almond shape is that it is easy to handle, the friction between coating materials is low, and the contact area is increased when coating the inner wall of the converter. The coating material is prepared, and the coating material manufactured by the above process is packaged and stored or sold. In the present embodiment, Bar coating the inner wall of the converter by using a pellet (pellet) formed and dried in the almond shape as described above, the coating method of the inner wall of the converter using the converter inner wall coating material according to the present invention is as follows. As shown in Fig. 2 and Fig. 3, the first coating process for filling the pellets 2 into the converter (1) after the tapping is completed, of the converter (1) filled with the pellet (2) A second coating process of coating the inner wall 1a of the converter 1 with the pellet 2 by injecting a high pressure nitrogen into the oxygen lance 2 after inserting the tip of the oxygen lance 2 into the inside; After the second coating process is completed, the oxygen lance 2 is drawn out from the converter 1 to form a third coating process of air-cooling the converter 1. Here, in the first coating process, after the tapping is finished, the converter 1 ) When the temperature inside is lowered to a certain temperature, a mixture of high purity MgO 85wt%-90wt% and CaCO ₃ 10wt%-15wt% Referenced is pelletized chungip the (2) in the interior of the converter (1) where the pellets (2) has compressive strength of 10Kg / cm ² -. 20Kg / cm ² for holding and also along the vertical and horizontal 30㎜ - 60 It is preferably formed in an almond shape having a size of mm, and filled in the converter 1 in an amount capable of coating the inside of the converter 1 as a whole. In addition, the temperature inside the converter 1 is 900 in the first coating process. When the temperature is lowered to about 1200 ° C., the pellet 2 is introduced into the converter 1. In the second coating process, the oxygen lance 3 is introduced into the converter 1 after the first coating process, but the oxygen The tip of the lance 3 is spaced apart from the upper portion of the pellet 2, the oxygen lance 3 is introduced into the converter 1, and then nitrogen is injected at a high pressure through the oxygen lance 3 to supply nitrogen. In this case, the pallet 2 is dispersed in the converter 1 and coated on the inner wall 1a of the converter 1. At this time, the oxygen lance 3 is coated. Injection pressure of nitrogen is injected through the 10Kg / cm ² -. It is preferred that to 20Kg / cm ² so that the CaCO ₃ incorporated in the limestone is thermally decomposed pelletized as to lose CO ₂ and, where the CO ₂ is discharged ( 2) to the inner wall 1a of the converter 1 more firmly, and the high purity CaO obtained by the heat treatment is mixed with the high purity MgO to maintain the fluidity of the slag and infiltration due to the maintenance of the saturated state of the MgO component in the slag. Of course, limestone containing CaCO ₃ (CO ₂ 40wt%-45wt% is mixed in salt) before CaCO _{3 is} 95.25wt%-97.65wt%, SiO ₂ 1.0wt%-1.5 wt%, Al ₂ O ₃ 0.25wt%-0.75wt%, MgO 1.0wt%-2.0wt%, Fe ₂ O ₃ 0.1wt%-0.5wt% and the composition ratio of and when thermally decomposed CO ₂ CaO 92.05wt%-95.51wt%, SiO ₂ 1.91wt%-2.51wt%, Al ₂ O ₃ 0.48wt%-1.26wt%, MgO 1.91wt%-3.34wt% and Fe ₂ O ₃ 0.19wt%-0.84wt % Composition In this case, when CaO contained in the high purity CaO is less than or exceeds 92.05wt% -95.51wt%, the erosion by the infiltration due to the maintenance of fluidity of the slag and the saturation of the MgO component in the slag is achieved. As a result, the pellets 2 dispersed at the injection pressure of nitrogen are coated with the inner wall 1a of the converter 1, and then the oxygen lances 3 are removed. The coating work is completed by drawing the outside of the converter 1, and after separating the oxygen lance 3 from the converter 1, the converter 1 is cooled by air. Here, in the present invention, the pellet 2 Maintaining the temperature at the time of injecting into the converter 1 is 900 ° C-1200 ° C to pyrolyze CaCO ₃ contained in the pellet ₂ to smoothly coat the inner wall 1a of the converter 1. In addition, the injection pressure of nitrogen injected from the oxygen lance (3) is 10K. is less than g / ㎝ ² pellets (2), the overall coating can not be properly scattered evenly difficult being done, 20Kg / ㎝ ² is greater than the pellets (2) scattering is too severe, such as drop and breakage of pellets in the coating of Thus, the converter inner wall coating material composition and the manufacturing method thereof according to the present invention and the coating method of the converter inner wall using the same are to easily extend the service life of the converter.

As described above, coating the inner wall of the converter using the coating material prepared according to the present invention is because the coating of the converter with the coating material composed of limestone mainly containing high purity MgO and CaCO ₃ having good corrosion resistance, Since the number of times of use can be extended to thousands of charges, the productivity can be improved, and there is an advantage that the coating material is superior to conventional coating materials.

Claims (6)

delete In the converter inner wall coating material composition, Pyrolysis of CO ₂ by heat treatment of magnesite containing MgCO ₃ MgO 95.33wt%-96.86wt%, SiO ₂ 0.60wt%-0.67wt%, Al ₂ O ₃ 0.12wt%-0.19wt% and CaO 2.42wt% High purity MgO 70 wt% consisting of a composition ratio of 3.81 wt%-84 wt%; CaCO ₃ 95.25wt%-97.65wt%, SiO ₂ 1.0wt%-1.5wt%, Al ₂ O ₃ 0.25wt%-0.75wt%, MgO 1.0wt%-2.0wt% and Fe ₂ O ₃ 0.1wt%-0.5 A converter inner wall coating composition comprising a mixed composition of limestone 16wt%-30wt% containing CaCO ₃ composed of a wt% composition ratio. In manufacturing the converter inner wall coating material, The MgCO ₃ 900 ℃ - the crushing by crusher so that the 130 mesh-a 30wt% 90 mesh to heat treatment at 1200 ℃ high purity MgO 70wt% obtained by thermal decomposition of CO ₂ - limestone 16wt% containing 84wt% and, CaCO ₃ 1 step; A second step of adding 15 wt% to 25 wt% of water to give moldability to the fine particles crushed by the first step, and mixing them using a mixer; The converter inner wall coating made of a third step of drying in 30 ℃ - the second molding the mixture was mixed by means of a process using a mold as almond shape and compressive strength of 10Kg / cm ² - 20 ℃ to be 20Kg / cm ² Manufacturing method. The method of claim 3, The high purity MgO is MgO 95.33wt%-96.86wt%, SiO ₂ 0.60wt%-0.67wt%, Al ₂ O ₃ 0.12wt%-0.19wt% and CaO 2.42wt%-3.81wt%, Limestone containing CaCO ₃ is composed of CaCO ₃ 95.25wt%-97.65wt%, SiO ₂ 1.0wt%-1.5wt%, Al ₂ O ₃ 0.25wt%-0.75wt%, MgO 1.0wt%-2.0wt % And Fe ₂ O ₃ 0.1wt%-0.5wt% manufacturing method of the inner wall coating material, characterized in that. The method of claim 3, The molding molded in the mold in the third step is the vertical and horizontal size of 30mm to 60mm, respectively, and the method of producing a converter inner wall coating material, characterized in that formed in the almond shape. In coating the inner wall of the converter with a coating material of 70 wt%-84 wt% of high purity MgO and 16 wt%-30 wt% of limestone containing CaCO ₃ , A first coating step of filling the interior of the converter in an amount to apply the coating material as a whole to the interior of the converter in a state where the temperature inside the converter is 900 ° C. to 1200 ° C .; A second coating step of the spray by 20Kg / cm ² as the pressure the coating material dispersed by the pressure of the nitrogen to be attached to the inner wall of a converter, wherein the first coating step is finished, a nitrogen with an oxygen lance 10Kg / cm ^2; The coating method of the inner wall of the converter consisting of a third coating step of taking out the oxygen lance from the converter and air-cooled after the second coating step.