KR100450370B1 - Dolomite waterless- monolithic lining material and its installation method - Google Patents

Abstract

The present invention relates to a lining material to be installed on the wall or floor of the tundish and molten steel ladle (ladle) for steel and steel casting, the lining material of the present invention is MgO-CaO clincher 80 ~ 98 weight %, 1-7% by weight of the powdery thermosetting resin, and 1-4% by weight of boric acid in the powder, characterized in that the mixture kneaded in an irregular form, the construction method is a predetermined distance to the internal surface of the refractory tundish and ladle Step of installing the iron mold, the step of introducing the lining material containing 1-7% by weight of the thermosetting resin and 1-4% by weight of boric acid as the main raw material between the internal refractories and the iron mold, vibration filling the injected lining material Comprising the step of heating, while circulating the filled lining material inside the iron mold for 2-4 hours in hot air of 200-400 ℃, removing the iron mold after curing the lining material It shall be.

Description

Dolomite waterless monolithic lining material and its installation method

The present invention relates to a lining material applied to the walls or floors of tundish and molten steel ladle (ladle) for steel and steel casting, more specifically, excellent corrosion resistance and adsorption capacity of non-metallic inclusions The present invention relates to a dolomite anhydrous amorphous lining material that can be applied by hot air heating without adding water, and to a tundish or ladle of the lining material.

Molten steel tapping out of the converter or electric furnace is taken to the ladle, and then transferred to a tundish and cast.

The bottom and wall surfaces of the tundish or ladle are embedded with refractory materials such as high alumina, Al ₂ O ₃ -SiO ₂ , and the like to withstand the high temperature environment of molten steel.

When the internal refractories are directly exposed to molten steel, the temperature of the molten steel decreases due to heat loss, and when the internal refractories are removed after operation, damage of the internal refractories is caused by mechanical shock. Lining material is constructed in.

As a conventional tundish lining material, MgO is used, which has a higher expansion and contraction rate than the internal refractories, so that it is less attached to the refractory during operation, and the dismantling property is good, so that the removal work is easy. .

However, conventional MgO-lined lining materials do not have the property of adsorbing many non-metallic inclusions generated in processes prior to tundish. Therefore, there is a problem in that a separate CaO quality ceramic filter dam, an Ar gas blowing dam, a CaO-based tundish flux or the like for adsorbing non-metallic inclusions in the tundish must be added, which is a factor of increasing the raw unit.

In addition, the conventional MgO-based lining material is constructed by a wet method, the moisture added during the construction, even if the pre-heating pre-heating the tundish enough to remain, the remaining moisture in the lining material, and thus is first taken H ₂ gas pick-up phenomenon occurs in molten steel, which causes a problem of steel defects. And conventionally used phenolic resins are difficult to develop strength without hexamine and have limitations in use due to the toxicity of the hexaamine.

Accordingly, the present invention has been invented to solve the above problems, the main raw material is dolomite or MgO-CaO quality clinker excellent in corrosion resistance and non-metal adsorption and removal ability, and as an additive thermosetting powder resin and high temperature for low temperature strength expression The lining material is composed of boric acid for strength expression, and the lining material is applied to the interior of the refractory surface of the tundish and ladle by hot air heating without adding moisture, thereby preventing steel defects caused by H ₂ gas pickup. It can be, and the clean steel can be produced by the adsorption effect of the non-metallic inclusions, while the corrosion resistance to the slag is improved, the construction work is to provide a simple dolomite anhydrous amorphous lining material and its construction method.

1-Adsorption degree of Al ₂ O ₃ according to the Examples and Comparative Examples of the present invention

The dolomite anhydrous amorphous lining material of the present invention for achieving the above object is kneaded in an amorphous form, including 80 to 98% by weight of MgO-CaO clinker, 1-7% by weight of thermosetting resin and 1-4% by weight of boric acid. It is done.

In addition, the MgO-CaO clinker of the lining material of the present invention is 65 ~ 85% by weight of electrolytic dolomite with a particle size of 0.8 ~ 0.074mm and molten dolomite 15 ~ 35 of a particle size of 0.074mm or less, molten natural dolomite at 2400 ~ 2600 ℃ in electric arc weight%; 65-85 wt% of electrolytic dolomite having a particle size of 0.8-0.074mm, molten natural dolomite at 2400-2600 ° C., and 15-35 wt% of high temperature sintered magnesia having a particle size of 0.074 mm or less, sintered magnesite at 1600-1800 ° C .; Or 65 to 86% by weight of the hot sintered dolomite having a particle size of 0.8 to 0.074 mm and 15 to 35% by weight of the hot sintered dolomite having a particle size of 0.074 mm or less after sintering at 1600-1800 ° C. after the natural dolomite and magnesite pulverized mixing. It is done.

In addition, the lining material of the present invention is completely cured at 150 ° C and characterized in that the thermosetting resin is a phenol resin powder (hexamine free) is not added (hexamine-based curing agent).

In the method of constructing the lining material of the present invention of the above characteristics, the step of installing a mold with a predetermined distance to the internal surface of the internal refractories of the tundish and ladle, the dolomite anhydrous amorphous form produced by the above method between the internal refractories and the iron mold Step of injecting the lining material, vibration charging of the added lining material, heating the filling lining material while circulating inside the iron mold for 2-4 hours with hot air at 200-400 ℃, removing the iron mold after curing the lining material It is characterized by consisting of steps.

The MgO-CaO clinker used as the main raw material of the present invention is excellent in corrosion resistance to slag and molten steel, and contains 10-55% of a Ca ⁺² component having a large self-diffusion coefficient compared to Mg ⁺² or Al ⁺³ . Adsorption capacity of inclusions Al ₂ O ₃ , SiO ₂ and the like is large, and thus inclusions in the steel can be prevented.

The thermosetting resin used as the additive of the present invention is added for low temperature strength expression of the lining body. That is, the curing temperature of the thermosetting resin is 150-400 ℃ to enable the formation of the construction body at low temperature by hot air heating. In addition, a hexamine-based curing agent is used as a thermosetting resin in the conventional MgO-based lining material, but in the present invention, a powdery phenol resin to which hexamine is not added is used. It has excellent characteristics such as liquefaction, redness and strength expression.

Meanwhile, the boric acid used as the additive of the present invention may be, for example, a boric acid having a B ₂ O ₃ content of 60% or more, a melting point of 600 ° C. or less and an average particle size of 0.1 mm or less, and a small amount for expressing high temperature strength of the construction body. Although the melting point is very low and reacts with the refractory material to form a low melting point material, it is difficult to be used as a high-temperature material, but in the present invention, by using a material that is less reactive with boric acid as the main raw material, the disadvantages of boric acid are utilized. It enables the development of secondary strength, and maintains the high temperature strength of the construction body at the temperature (400-1000 ℃) before the high-temperature ceramic bond is formed by preheating. As a result, the manufacture of the product is completed in a state where physical properties are not determined (particle mixture state), and the physical properties are expressed by the user's use. This mechanism is designed to be included in the material.

As a construction equipment for the lining material, a tungsten mold for installing the lining material on the surface of a built-in refractory of tundish and ladle, a rod-shaped vibrator for filling, and a hot air dryer for expressing strength of the resin and boric acid are used. .

Hereinafter, the manufacturing method of the present invention will be described in detail with reference to Examples.

(Example 1)

Natural dolomite is placed in an electric arc furnace and melted at a temperature of 100 ± 2500 ° C. to obtain an electrolytic dolomite coagulum.

The coagulum is pulverized and classified to obtain 75% by weight of particles of 0.8 mm or less and 25% by weight of particles of 0.074 mm or less.

4 wt% of a phenolic thermosetting resin and 2 wt% of boric acid are added to the prepared electrolytic dolomite particles. Here, the addition ratio of the resin and boric acid is a blending ratio with respect to 100% by weight of the electrolytic dolomite particles.

The blend is dried in a hot air dryer at 200 ° C. for 2 hours.

The physical properties, erosion resistance, and adsorption ratio of Al ₂ O ₃ of the dolomite anhydrous lining material prepared as described above were measured and the results are shown in Table 1 and FIG. 1.

The erosion resistance measures the erosion results for the erosion flux containing MgO, Al ₂ O ₃ , SiO ₂ , CaO, Fe ₂ O ₃ and the like for 6 hours at 1550 ℃ to investigate the corrosion resistance against slag When the erosion rate of Comparative Example 2, which will be described later, is set to 100, this is expressed as a relative erosion index. The chemical composition of the erosion flux is shown in Table 2.

In addition, the degree of adsorption of Al ₂ O ₃ , which is a non-metallic inclusion, was investigated through the chemical component analysis after the erosion test of the specimen.

On the other hand, the dolomite anhydrous lining material of the present invention prepared as described above, first inserted into the tundish and ladle the iron mold produced to have a predetermined distance from the interior of the refractory surface, the lining material is introduced between the gap, rod Filled while removing air in the lining material using a vibrator, and then heated for 2-3 hours by circulating the hot air of 200-400 ℃ inside the iron mold using a hot air dryer to meet the characteristics of the present invention, curing the lining material It is then constructed by removing the iron mold.

Here, due to the structure of the tundish, the bottom portion of the bottom portion is inserted into the lining material before the iron mold is inserted into a predetermined thickness, and the nozzle portion is covered with a nozzle cover so as to secure the tapping hole and then lining work is performed.

In addition, it is preferable to apply a release material on the surface of the iron mold before the lining material to facilitate the removal of the iron mold after hot air heating.

The hot air dryer used in the present invention has a strength expression temperature range of 150-400 ° C. of the thermosetting resin, and if it is out of the range, it is impossible to form a construction body, so that a hot air dryer is designed to be heated in this temperature range.

(Example 2)

Sintered magnesia is obtained by crushing particles of natural magnesite into pellets and sintering at a temperature of 100 ± 1700 ° C. in a rotary furnace.

The sintered compact is ground and classified to obtain 25% by weight of particles of 0.074 mm or less.

75% by weight of particles of 0.8 mm or less of electrolytic dolomite prepared in Example 1 were blended with the finely divided sintered magnesia.

4% by weight of the phenolic thermosetting resin and 2% by weight of boric acid are respectively added to the blend and dried for 2 hours in a hot air dryer at a temperature of 200 ° C.

The physical properties, erosion resistance, and adsorption ratio of Al ₂ O ₃ of the specimen were measured in the same manner as in Example 1, and the results are shown in Table 1 and FIG. 1.

(Example 3)

After pulverizing high purity natural dolomite and magnesite, a synthetic combination is made, which is formed into pellets, and sintered at a temperature of 100 ± 1700 ° C. in a rotary furnace to obtain a MgO-CaO clinker.

The sintered compact was pulverized and classified to obtain 75% by weight of particles of 0.8 mm or less and 25% by weight of particles of 0.074 mm or less, and then 4% by weight of a phenolic thermosetting resin and 2% by weight of boric acid were added thereto. Dry for 2 hours in a hot air dryer at a temperature of ℃.

The physical properties, erosion resistance, and adsorption ratio of Al ₂ O ₃ of the specimen were measured in the same manner as in Example 1, and the results are shown in Table 1 and FIG. 1.

(Comparative Example 1)

Sintered magnesia prepared in Example 2 takes 75% by weight of the particles of 0.8mm or less, 25% by weight of the particles of 0.074mm or less, 3% by weight of hexaamine-based thermosetting resin, 1% by weight of fire clay (ball clay), sodium phosphate (monosodium) After adding 2.5% by weight of phosphate, it is dried for 2 hours in a hot air dryer at 200 ° C.

The physical properties, erosion resistance, and adsorption ratio of Al ₂ O ₃ of the specimen were measured in the same manner as in Example 1, and the results are shown in Table 1 and FIG. 1.

(Comparative Example 2)

Sintered magnesia prepared in Example 2 takes 75% by weight of the particles of 0.8mm or less, 25% by weight of the particles of 0.074mm or less, 1% by weight of silica flour, 1% by weight of refractory clay, 0.5% by weight of heat inhibitor, 0.02% by weight of the bubble generator and 2% by weight of powdered sodium silicate are added to form a slurry, followed by drying for 2 hours in a hot air dryer at a temperature of 200 ° C.

The physical properties, erosion resistance, and adsorption ratio of Al ₂ O ₃ of the specimen were measured in the same manner as in Example 1, and the results are shown in Table 1 and FIG. 1.

division Furtherance Example Comparative example Raw material Granularity One 2 3 One 2 Raw materials Dolomite Cleaner 0.8mm or less 75 75 0.074mm or less 25 MgO-CaO Cleaner 0.8mm or less 75 0.074mm or less 25 Sintered Magnesia 0.8mm or less 75 75 0.074mm or less 25 25 25 Thermosetting resin (hexamin free) 4 4 4 Boric acid 2 2 2 Thermosetting resin (hexamine type) 3 Fireclay One One Sodium Phosphate 2.5 Silica flower One Bubble generator 0.02 An anti-heating agent 0.5 Powdered Sodium Silicate 2 Experiment result Chemical composition (%) MgO 42.4 58.7 68.9 92.0 87.6 CaO 46.8 30.4 23.8 1.5 1.5 SiO ₂ 2.0 1.1 1.2 3.6 8.6 Volume specific gravity 200 ℃ 1.77 1.80 1.80 1.82 1.75 1500 ℃ 2.09 2.10 2.10 2.15 2.17 Compressive strength (kg / cm ² ) 200 ℃ 60 68 70 60 15 1200 ℃ 65 77 80 70 25 1500 ℃ 100 120 125 95 45 Erosion Result Erosion Index 40 30 25 50 100

Chemical Composition of Erosion Flux Chemical composition (%) MgOAl ₂ O ₃ SiO ₂ CaOFe ₂ O ₃ 0.2442.312.1450.531.06

As shown in Table 1, using dolomite clinker, MgO-CaO clinker and magnesia according to the embodiment of the present invention as fine powder, 1-7% by weight of thermosetting resin (hexamine free), 1-4% by weight of boric acid In case of addition, when the demold of iron mold was demolished, the strength and the erosion resistance against the erosion flux were excellent.

In addition, in the embodiment of the present invention, as the dolomite and MgO-CaO materials having high CaO content are adopted, the CaO component reacts with Al ₂ O ₃ contained in the tundish flux so as to react with 3CaO ₅ Al ₂ O ₃ , CaO _{· Al 2 O 3, 12CaO ·} 7Al 2 O to generate a compound such as _3, so that it can confirm the that the suction effect of the Al ₂ O ₃ inclusions, superior compared to the comparative example, as shown in FIG.

As described above, the dolomite anhydrous amorphous lining material of the present invention is not only excellent in corrosion resistance to slag, but also very useful for preventing steel defects and producing clean steel due to the adsorption effect of non-metallic inclusions by CaO component.

In addition, the lining material of the present invention uses a thermosetting powdery phenolic resin that does not contain hexamine cured at low temperature and boric acid expressing strength at high temperature as an additive, and correspondingly to the low temperature strength of the lining material by hot air heating without moisture addition. By adopting a construction method that expresses high temperature strength up to preheating, it is possible to prevent H ₂ gas pickup due to residual moisture during construction, thereby preventing steel defects inherently. Particularly, in the present invention, powdered phenol without addition of hexamine is present. While using resin, it has overcome the conventional limitations of strength, which is difficult to develop without strong hexamine, due to its excellent liquefaction, wetting and strength expression under the conditions of use, and also has a very low melting point and low reaction with refractory materials. Rather than the disadvantages of boric acid, a material that is difficult to be used as a high-temperature material by forming a melting point material Be the use strength enabled the strength of the temperature difficult.

In addition, since it is manufactured in an indefinite shape, excellent physical properties are expressed in the user's use process, so it is convenient and efficient in use, and the construction of lining material is easy, and the time required from casting of ladle to casting of molten steel by tundish is shortened. Significantly improved efficiency results in more stable operation.

Claims (5)

A dolomite anhydrous amorphous lining material characterized by kneading in an irregular form, including 80 to 98% by weight of MgO-CaO clinker, 1-7% by weight of thermosetting resin, and 1-4% by weight of boric acid. The method of claim 1, wherein the MgO-CaO clinker 65-85 wt% of electrolytic dolomite having a particle size of 0.8-0.074 mm and 15-35 wt% of electrolytic dolomite having a particle size of 0.074 mm or less; 65-85 wt% of electrolytic dolomite having a particle size of 0.8-0.074mm, molten natural dolomite at 2400-2600 ° C., and 15-35 wt% of high temperature sintered magnesia having a particle size of 0.074 mm or less, sintered magnesite at 1600-1800 ° C .; or Characterized in that it is any one selected from 65 ~ 86% by weight of the hot sintered dolomite having a particle size of 0.8 ~ 0.074mm and 15 ~ 35% by weight of the high temperature sintered dolomite having a particle size of 0.074mm or less after sintering at 1600 ~ 1800 ° C after pulverizing and mixing natural dolomite with magnesite Dolomite anhydrous amorphous lining material. delete The dolomite anhydrous amorphous lining material according to claim 1 or 2, wherein the thermosetting resin is a powdery phenol resin to which hexamine is not added. Installing an iron mold at predetermined intervals into the tundish and ladle interior refractory surface; Injecting a dolomite anhydrous amorphous lining material prepared by the method of claim 2 between the internal refractories and the iron mold; Vibration-filling the injected lining material; Heating the filled lining material while circulating the inside of the iron mold with hot air at 200-400 ° C. for 2-4 hours; Method for constructing a dolomite anhydrous amorphous lining material, characterized in that consisting of the step of removing the iron mold after curing the lining material.