KR102102820B1 - The Bottom Gas Bubbling MgO Refractory composition to Relieve Thermal Stress and the product manufacturing Method - Google Patents

Abstract

A low-odor magnesia carbonaceous refractory composition for resolving thermal stress and a method for manufacturing the same are provided.
The composition for refractory magnesia carbonaceous refractory of the present invention is composed of a main raw material composed of 75% to 85% by weight of an electrolytic magnesia clinker and 15 to 25% by weight of impression graphite, and 100 parts by weight of the coal based pitch. 0.5 to 3.0 parts by weight; 0.5 to 5.0 parts by weight of a no-block type phenolic powder binder; Frit 0.5 ~ 5.0 parts by weight having a melting temperature of 750 ~ 950 ℃; And 1.0 to 5.0 parts by weight of aluminum powder, and the electrolytic magnesia clinker has a weight percent of itself, 10 to 25 percent of electrolytic magnesia clinker having a particle size of 3 to 5 mm, and 25 to 25 percent of electrolytic magnesia clinker having a particle size of 1 mm or less. It is characterized by being composed including 35%.

Description

{The Bottom Gas Bubbling MgO Refractory composition to Relieve Thermal Stress and the product manufacturing Method}

The present invention relates to a low-odor magnesia carbonaceous refractory composition and a refractory production method capable of reducing erosion of a low-odor nozzle refractory in a converter.

Magnesia refractory material (MgO-C Brick) containing carbon is used as an interior material to protect equipment by the high temperature of molten iron or molten steel in the steelmaking process. The reason why the carbon-containing magnesia refractory material is used as a protective material is that the wettability caused by slag generated during refining is low, and the surface area for chemical reaction is small, so it has excellent corrosion resistance. In addition, since the impression graphite with high thermal conductivity is used as a raw material for carbon, the function of preventing cracking and dropping of the refractory due to expansion and contraction due to thermal gradient is superior to that used by the Magnesia clinker alone. Due to this characteristic. Carbon-containing magnesia refractories are widely used as protective materials for equipment for purifying impurities in molten steel.

However, in the process of controlling the carbon component and impurities in the steel, the maintenance and repair time of the equipment must be short, so that the quality and productivity of the product can be improved. Therefore, the long life of the magnesia refractory material containing carbon, which is an interior repair material, is required. In particular, in the case of converter odor, in case of refractory damage and deepening of erosion, direct repair such as spray reinforcement performed at other site damage cannot be performed, leading to floor coating through the remaining slag, or lowering the gas flow rate to a specific odor site to reduce erosion rate. It is inevitable to protect the refractories in an indirect way, such as by reducing. This causes odor clogging and can affect steel quality such as inhibiting the kneading properties of molten steel, so refractories for odor are required to have a longer life than other parts in the converter.

Therefore, the present invention optimizes the composition and particle size of the raw material of a kneaded product in terms of securing excellent porosity, elastic modulus, and thermal expansion coefficient of the magnesia refractory material containing carbon, and a composition for low-odor magnesia carbonaceous refractory material and a low-odor magnesia car using the same It is an object to provide an intrinsic refractory production method.

In addition, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned are clearly understood by those skilled in the art from the following description. It could be.

The present invention for achieving the above object,

The main raw material is composed of 75% to 85% by weight of electrolytic magnesia clinker and 15% to 25% by weight of impression graphite,

With respect to 100 parts by weight of the main raw material, coal-based pitch 0.5 to 3.0 parts by weight; 0.5 to 5.0 parts by weight of a no-block type phenolic powder binder; Frit 0.5 ~ 5.0 parts by weight having a melting temperature of 750 ~ 950 ℃; And 1.0 to 5.0 parts by weight of aluminum powder,

The electro-melting magnesia clinker is a odorless magnesia car, characterized in that it comprises 10 to 25% of an electro-magnesia clinker having a particle size of 3 to 5 mm and 25 to 35% of an electro-magnesing magnesia clinker having a particle size of 1 mm or less. The present invention relates to a composition for refractory materials.

It is preferable that the residual carbon measured at 800 ° C satisfies 40 to 60% by weight of the noblock-based phenolic powder binder.

The average particle size of the aluminum powder may be 10 ~ 45㎛.

The coal-based pitch may have a softening point of 200 to 250 ° C. and an average particle size of 40 to 60 μm.

In addition, the present invention,

After kneading the composition prepared as described above, filling the mold, isotropically press-molding with a force of 0.8 to 1.6 ton / cm 2 to produce a cylindrical core portion refractory molded product, and then applying a carbon-based adhesive to the surface;

After fixing the refractory molded article of the core portion to the center of the well block mold, filling the composition for the well block portion and isostatically pressing it with a force of 1.0 to 1.8 ton / cm 2 to produce a cylindrical deodorized refractory molded article having a boundary portion; And

It relates to a method for manufacturing a low-odor magnesia carbonaceous refractory material comprising; a step of drying the molded article.

In addition, the present invention,

After kneading the composition prepared as described above, after installing a temporary masking film at the center of the well block mold, the core part composition is filled therein, and the outside of the masking film is filled with a composition for a well block part, and then the temporary masking film is removed and 0.8 A process of manufacturing a cylindrical deodorized refractory molded article having a boundary portion by isotropic pressing molding with a force of ˜1.6 ton / cm 2; And a step of drying the molded molded article.

The drying process,

First drying the molded product in a hot air drying furnace at a temperature of 120 to 180 ° C. for 4 to 8 hours; And a step of secondarily drying the first dried molded product at a temperature of 180 to 300 ° C. for 12 to 16 hours.

In the low-odor refractory material, the fixed carbon content of the refractory material of the core portion is 5 to 20% by weight higher than that of the well-block portion, so that the well-block portion is pre-damaged before the core portion and the thermal stress applied to the entire refractory material can be primarily resolved. It is desirable.

According to the present invention, in terms of the raw material composition of the carbon-containing magnesia refractory material, coal-based pitch, no-block-based phenolic powder binder, Frit, Al metal are optimally blended, and the main raw material magnesia clinker is assembled into a granular composition to optimize refractory. It is possible to effectively provide a composition for refractory nozzle refractory of a converter capable of ensuring long life by minimizing thermal stress and having heat-resistant spalling properties.

1 is a longitudinal cross-sectional view showing a low-odor refractory body according to an embodiment of the present invention.
2 is a view showing the upper surface of the odor-resistant refractory of FIG.
3 is a schematic view showing the thermal environment and tensile stress analysis when the hot use of the odor refractories of FIGS. 1 and 2.
4 is a cross-sectional view of the odor-resistant refractory material after use, and is a photograph showing the form of penetration and cracking of molten steel.

Hereinafter, the present invention will be described.

1 is a longitudinal sectional view showing the body of the odorous refractory body according to an embodiment of the present invention, FIG. 2 is a view showing the upper surface of the odorous refractory body of FIG. 1, and FIG. 3 is used during the hot use of the odorous refractory bodies of FIGS. 1 and 2 It is a schematic diagram showing thermal environment and tensile stress analysis.

The present invention is to improve the thermal shock resistance to the pipe core (Well Block) portion refractory material (corresponding to reference numerals 11 and 12 of FIGS. 1 and 2) through which cooling gas vulnerable to thermal shock flows out of the low refractory portion. In particular, by lowering the coefficient of thermal expansion in the medium temperature region (about 600 ~ 800 ℃) of the material, it is a technique to solve the stress imbalance (see Fig. 3) of the material according to the temperature region according to the structure of the low-odor refractory material. To this end, the main raw material was focused on resolving the thermal stress generated in the refractory material by assembling such as increasing the distribution of the 3-5 mm-size pre-melting magnesia in terms of the overall particle size, and lowering the distribution of the pre-melting magnesia below 1 mm. The core and well block parts are differentiated from each other, and thermal shock is minimized by using double-forming and thermally conductive carbon-based adhesives.

Accordingly, the present invention is a composition for a refractory nozzle odor refractory composition, in weight percent, based on 100 parts by weight of a main raw material comprising 75 to 85% of electrolytic magnesia clinker and 15 to 25% by weight of impression graphite, and 100 parts by weight of the main raw material. Pitch 0.5 to 3.0 parts by weight; 0.5 to 5.0 parts by weight of a no-block type phenolic powder binder; Frit 0.5 ~ 5.0 parts by weight having a melting temperature of 750 ~ 950 ℃; And 1.0 to 5.0 parts by weight of aluminum powder. In addition, the electrolytic magnesia clinker has a weight percentage of itself, and includes 10 to 25% of electrolytic magnesia clinker having a particle size of 3 to 5 mm, and 25 to 35% of electrolytic magnesia clinker having a particle size of 1 mm or less.

In addition, when forming a low-odor refractory material, a core part is first molded, a carbon-based adhesive is applied to the core surface, and then double-molding is performed by filling and mixing a well block part kneaded material. As such an effect, it is possible to prolong the longevity of the integrity of the inner core portion, such as crack and propagation from the outside due to the formation of the interface between the core and the well block portion, and the penetration of molten steel is limited to the well block. At this time, the effect can be weighted by differentiating the material of the core portion with a fixed carbon content of 5 to 20% by weight higher than the well block portion.

Hereinafter, the composition and content limitation reasons of the composition for refractory nozzle refractory nozzle of the present invention will be described.

First, the refractory composition of the present invention is composed of 75% to 85% of electrolytic magnesia clinker and 15% to 25% of impression graphite as the main raw material.

The electro-melting magnesia is manufactured by melting MgO in an ARC electric furnace, and is a raw material having excellent crystallinity, thereby improving the life of the converter by increasing refractory strength and high corrosion resistance to slag. The impression graphite is excellent in thermal shock resistance due to its high thermal conductivity inherent in carbon, and is used for corrosion resistance and structural spalling reduction due to its low wettability to the slag of carbon.

In the present invention, it is preferable to limit the content of the pre-melting magnesia to 75 to 85% by weight, and to limit the content of the impression graphite to 15 to 25% by weight. If the total melting magnesia content is less than 75% by weight and the impression graphite exceeds 25%, the strength of the refractory material is weakened, which may cause physical damage due to molten steel flow and increase the erosion rate. In addition, if the total melting magnesia content exceeds 85% by weight, and the impression graphite is less than 15% by weight, it causes problems in the stable use of refractory materials by causing rapid thermal spalling of the odorous refractory material in which the high molten steel temperature of the cooling gas and the movable surface coexist. Because there may be.

Furthermore, in the present invention, the main raw material, magnesia clinker, is composed of 10% to 25% of magnesia clinker having a particle size of 3 to 5 mm, and 25 to 35% of magnesia clinker having a size of 1 mm or less (residual components are). Magnesia clinker having a particle size distribution exceeding 1 ~ 3mm and 5mm), magnesia clinker If the particle size of aggregate is composed of 25% or more and 3% or less of 1mm or less and 25% or less, the porosity of the molded product may increase. The thermal stress such as the elastic modulus is reduced, so that the thermal shock resistance can be improved, but wear of the molten steel and corrosion resistance due to slag can be significantly reduced. Conversely, when the particle size of aggregate is composed of less than 10% of those with 3 to 5 mm magnesia clincher and more than 35% with less than 1 mm, the contact area between aggregates increases to increase sintering characteristics, resulting in lower porosity and improved strength. It can have a good effect on wear resistance and corrosion resistance due to slag, but it can shorten the service life such as the thermal shock resistance is lowered and the propagation of cracks in the refractory matrix is expanded.

In addition, in the composition for refractory nozzle refractory of the present invention, in addition to the main raw material composition, Frit, coal-based pitch, and a high-carbon noblock-based phenolic powder binder and aluminum powder are included as additives. Specifically, with respect to 100 parts by weight of the main raw material, coal-based pitch 0.5 to 3.0 parts by weight; 0.5 to 5.0 parts by weight of a no-block type phenolic powder binder; Frit 0.5 ~ 5.0 parts by weight having a melting temperature of 750 ~ 950 ℃; And 1.0 to 5.0 parts by weight of aluminum powder.

First, the coal-based pitch raw material, which is one of the core compositions of the present invention, preferably has a softening point of 200 to 250 ° C and an average particle size of 40 to 60 μm.

If a pitch with a softening point of less than 200 ° C is used, there is a possibility of appearance cracking in the product due to volatile organic compounds of the raw material during molding and drying. On the other hand, when a pitch with a softening point exceeding 250 ° C. is used, the pitch of the refractory material is not liquefied and the process of penetrating the graphite and the binder present in the kneaded product is omitted, thereby reducing the density of the product structure and There is a possibility of peeling from other aggregates due to aggregation.

In addition, when the particle size exceeds 60 µm, dispersion in the kneaded material becomes difficult, and thus the general properties (porosity, compressive strength, specific gravity) required in the molded product are lowered, and the hot strength and spalling resistance required for the actual use of the product are not exhibited. On the other hand, when a raw material having a particle size of less than 40 µm is used, kneading properties are better, so that general properties and the like are expected to increase somewhat, but since it is not commercially available as a general-purpose raw material, use may be restricted.

Meanwhile, in the present invention, it is preferable to control the addition amount of the coal-based pitch to 0.5 to 3.0 parts by weight with respect to 100 parts by weight of the main raw material composition. The pitch of less than 0.5 parts by weight is a small amount to develop medium temperature strength due to insufficient carbon bonding due to lack of carbon source after thermal decomposition, and does not affect reduction of thermal stress such as elastic modulus due to formation of fine pores. When the pitch composition exceeds 3.0 parts by weight, the general properties of the product are inhibited due to the tendency to aggregate between the pitches when kneading, and the product strength and the probability of cracking are high due to excessive volatile content.

In addition, the noblock-based phenolic powder binder is preferably added in a range of 0.5 to 5.0 parts by weight based on 100 parts by weight of the main raw material composition. Addition of the desired amount of the powder binder can control the porosity targeted in the drying process after molding the kneaded material, which can be used for erosion resistance and thermal stress relaxation of the material. If the addition amount is less than 0.5 parts by weight, the aromatic compound in the binder is small, and the residual carbon amount polymerized after thermal decomposition is insufficient, and if it exceeds 5.0 parts by weight, molding and drying are caused by agglomeration and volatilization of the powder binder generated during kneading. In the process, it may cause cracking of the refractory material.

In the present invention, the Frit is preferably used a material having a melting temperature of 750 ~ 950 ℃. Since the ambient temperature of the cooling gas pipe of the odor-resistant refractory material in use is about 400 to 1000 ° C depending on the position relative to the movable surface, the frit forms a liquid phase in this temperature range, thereby resolving thermal stress such as melting with surrounding tissues and reducing elastic modulus. In the present invention, the addition amount of the frit should be added in a range of 0.5 to 5.0 parts by weight with respect to 100 parts by weight of the main raw material. If it is less than 0.5 part by weight, when the frit reaches the melting temperature, it only fuses locally with the surrounding tissue, causing physical property variations. On the other hand, when it is added in excess of 5.0 parts by weight, the liquid phase is excessively formed due to Si, Na, and B materials in the frit, and thus the erosion rate of the refractory material can be accelerated due to a decrease in hot strength and abrasion resistance.

In the present invention, it is preferable that the Al metal powder has a purity of 99.5% or more and an average particle size of 10 to 45 μm. When these powders are used, aluminum carbide or alumina reacts with surrounding carbon and oxygen from 660 ° C. after aluminum is melted. By promoting formation, it begins to impart hot strength. In addition, the role of the aluminum powder in the present invention has a function of alleviating the porosity rapidly increasing by thermal decomposition of the binder and the coal-based pitch in the range of 600 to 1000 ° C with an aluminum reactant. The smaller the average particle size is in the µm unit, the higher the area in contact with the graphite and carbon source increases, so the medium temperature and hot strength of the material increases, and it is effective in alleviating the rapid increase in porosity, but it is explosive in manufacturing due to dust. Due to the risk, there are restrictions on its use.

Even if aluminum powder having an average particle size of 45 to 70 µm is used, there are no significant problems in the function of preventing oxidation of graphite, etc., but if a uniform clay is not formed, sintering of aluminum starting from 660 ° C or higher and localized in the carbon bonding temperature range As a result, rapid volume expansion may occur and cracks may occur.

In the present invention, it is preferable to manage the addition amount of the aluminum powder in a range of 1.0 to 5.0 parts by weight with respect to 100 parts by weight of the main raw material. The addition amount of less than 1.0 part by weight is high in the carbon content in the clay composition corresponding to the present invention, so it is difficult to expect an anti-oxidation effect. This is because the amount of addition exceeding 5.0 parts by weight may cause structural spalling, such as a large amount of aluminum being oxidized or carbon bonds to break the matrix prior to the anti-oxidation effect.

Next, by using the composition for refractory nozzle refractory material of the present invention, a molding method capable of alleviating the thermal shock resistance when forming a refractory refractory material will be described in detail.

 A mixture of magnesia clinker, impression graphite, additives described above and a liquid binder is prepared, and then filled with a pipe in a core portion. This is isotropically press-molded with a force of 0.8 to 1.6 ton / cm 2 to produce a refractory cylindrical core having a diameter of 300 mm and a height of 1800 mm, and a carbon-based adhesive is applied to the surface.

Subsequently, the core block refractory material is fixed to the center of the rubber block of the well block portion, and the remaining space in the mold is filled with the corresponding kneaded material. Afterwards, an isostatic press-molding is performed once again with a force of 1.0 to 1.8 ton / cm 2 to produce a cylindrical deodorizing refractory material having a final diameter of 600 mm and a height of 1800 mm. When the double pressure is applied by varying the pressure applied to the core portion and the well block portion, when the penetration and cracking of molten steel occurs in the odor-resistant refractory material in use, only the core portion is damaged due to the interface, or the well block portion is removed. It is possible to extend the service life of the overall low-odor refractory material, such as being damaged and eliminated. If the core portion and the well block portion are formed at a rate of less than 0.8 to 1.0 ton / cm 2, the porosity of the refractory material increases and the molding strength is insufficient, so that the erosion resistance and the rate of refractory erosion due to abrasion can be improved. When forming a block part, if it exceeds 1.6 to 1.8 ton / cm 2, the specific gravity and strength of the refractory material may increase, but after forming and drying, appearance cracks may occur, and the inner pipe may be damaged, and thus it may not be used as a refractory refractory material. .

In addition, if the material of the core portion and the well block portion are differentiated, the above effect may be more pronounced. In the present invention, it is preferable to increase the fixed carbon of the core part refractory material to a level of 5.0 to 20.0% by weight compared to the well block part.

If the fixed carbon of the refractory material of the core portion is less than 5.0% by weight compared to the well block portion, the phenomenon that the well block portion is pre-damaged is extremely small, and the fixed carbon deviation of the material of the well block portion itself is easy to maintain less than 5.0% by weight. Therefore, the material difference according to the structure is difficult to realize due to manufacturing conditions. On the other hand, if the fixed carbon of the refractory material in the core portion exceeds 20.0% by weight compared to the well block portion, the fixed carbon content in the well block portion is lowered and becomes vulnerable to spalling resistance along with variation in the material, so there is a risk of shortening the life of the deodorized refractory material. have.

Alternatively, in the present invention, the composition is not molded separately at the time of molding, and after the prepared composition is kneaded, a temporary masking film is installed at the center of the well block mold, and the core part composition is filled therein, and outside the masking film After filling with the composition for a well block portion, and then removing the temporary masking film, isotropic pressing is performed to produce a cylindrical deodorized refractory molded article having a boundary portion.

Subsequently, the deodorized refractory material molded as described above is dried. Preferably, after primary drying at a temperature of 120 to 180 ° C for 4 to 8 hours in a hot air drying furnace, secondary drying at 180 to 300 ° C for 12 to 16 hours is performed to stably cure the phenolic liquid binder and powder binder. , By forming an even porosity throughout the matrix, a low-odor refractory material having good specific gravity, strength, and elastic modulus can be produced.

If the drying process is not divided into two stages, and drying from the initial stage to 300 ° C in one stage, curing of the binder in the refractory material is not sufficiently achieved, and molding appearance cracking may occur due to loss of carbon source due to the generation of volatile components. Residual carbon may decrease, resulting in a decrease in specific gravity and initial strength. Likewise, if the drying time is lower than the temperature suggested in the present invention during the primary and secondary drying processes or the drying time is short, the strength and specific gravity of the product are lowered due to uncuring of the phenol binder, and when used in the furnace, it is vulnerable to penetration and abrasion resistance of molten steel. It can shorten the life of the product. In addition, when the drying temperature is higher than the temperature suggested in the present invention or the drying time is long, curing of the binder rapidly progresses or the porosity of the product is excessively high due to loss due to oxidation, and thus may be vulnerable to corrosion resistance and abrasion resistance during use. , The loss of local binders can cause structural spalling.

Hereinafter, the present invention will be described in detail through examples.

Example 1

First, in order to prepare a refractory kneaded product in the core part, a main raw material containing 80% by weight of an electrolytic magnesia clinker with a purity of 97.5% or more and 20% by weight of flake graphite was introduced into a kneader and kneaded. . At this time, the main raw material, the whole magnesia, had its own weight, and the proportion of those having a particle size of 3 to 5 mm was 20%, and that of 1 mm or less was 30%. On the other hand, the aluminum powder having an average particle size of 35 µm, based on 100 parts by weight of the main raw material, 2.5 parts by weight of a no-block type phenolic powder binder having 50% by weight of residual carbon, 2.5 parts by weight of Frit, a coal temperature pitch with a softening point of 210 ° C. and an average particle size of 50 μm 2.5 parts by weight was pre-kneaded for 10 minutes.

The pre-kneaded fine powder composition was introduced into a kneader having a clinker and impression graphite and kneaded for 15 minutes, and then 3.0 parts by weight of a phenolic liquid binder was added to knead for 30 minutes to prepare a low-odor refractory composition for the core.

Next, the well block (Well Block) refractory kneaded material production is the same as the method for producing a refractory kneaded material of the core part, except that 83% by weight of an electrolytic magnesia clinker with a purity of 97.5% or more and 23% by weight of impression graphite are used.

The composition thus obtained was isotropically press-molded with a force of 1.2 ton / cm 2 to produce a core part refractory in a cylindrical shape of 250 mm in diameter and 300 mm in height, and coated with a carbon-based adhesive on the outer surface and fixed to the center of a small well block mold The composition for the block portion was filled and isostatically press molded with a force of 1.3 ton / cm 2 to prepare a sample having a diameter of 450 mm and a height of 350 mm. The sample was first dried for 6 hours at a temperature of 140 ° C, and then dried for 2 hours at a temperature of 240 ° C to produce a final product. The sample was prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Example 2

A composition for odor-resistant refractories was prepared through the same manufacturing process as in Example 1, but afterwards, the obtained composition was not molded separately, and the pipe and core composition were filled together with a temporary masking film at the center of the well block mold, and the rest After filling with the well block portion composition, the temporary masking film was removed and isostatically press molded with a force of 1.3 ton / cm 2 to prepare a sample having a diameter of 450 mm and a height of 350 mm.

The sample was prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 1

The main raw material used in Example 1 is an electrolytic magnesia clinker, which is used by configuring the particle size of the aggregate to include 8% of its particle size, 3% to 5mm, and 42% of 1mm or less. A composition for a odorless refractory was prepared through the same manufacturing process as in Example 1 except for the point.

Subsequently, the obtained composition was prepared in the same manner as in Example 1, and samples were prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 2

A composition for refractory refractories was prepared through the same manufacturing process as in Example 1, except that 2.5 parts by weight of the coal-based pitch having a softening point of 210 ° C. and an average particle size of 50 μm used in Example 1 was not used.

Subsequently, the obtained composition was prepared in the same manner as in Example 1, and samples were prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 3

A composition for a low-odor refractory was prepared through the same manufacturing process as in Example 1, except that 2.5 parts by weight of Frit having a melting point of 750 to 950 ° C used in Example 1 was not used.

Subsequently, the obtained composition was prepared in the same manner as in Example 1, and samples were prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 4

The same manufacturing process as in Example 1, except that 2.5 parts by weight of the residual carbon percentage 50% by weight used in Example 1, a noblock-based phenolic powder binder, and 0.2 parts by weight of a liquid phenol binder curing agent, hexamethylenetetramine, are used. To prepare a composition for low-odor refractories

Subsequently, the obtained composition was prepared in the same manner as in Example 1, and samples were prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 5

A composition for low-odor refractories was prepared through the same manufacturing process as in Example 1, except that 0.8 parts by weight was used instead of 2.5 parts by weight of aluminum powder having an average particle size of 40 μm used in Example 1.

Subsequently, the obtained composition was prepared in the same manner as in Example 1, and samples were prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 6

A composition for a low-odor refractory material was prepared through the same manufacturing process as in Example 1, and then, the obtained composition was molded in the same manner to prepare a sample having a diameter of 450 mm and a height of 350 mm. However, the sample was first dried for 3 hours at a temperature of 120 ° C, and then dried for 2 hours at a temperature of 180 ° C.

The sample was prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

Comparative Example 7

A composition for deodorizing refractories was prepared through the same manufacturing process as in Example 1, except that 0.45 parts by weight was used instead of 2.5 parts by weight of the residual carbon content of 50% by weight used in Example 1 of the noblock-based phenol powder binder.

Subsequently, the obtained composition was prepared in the same manner as in Example 1, and samples were prepared and analyzed according to each evaluation method, and the results are shown in Table 1.

-Specimen analysis and evaluation results-

Volume specific gravity, porosity (%), compressive strength, hot bending strength, single-sided heating spalling test, room temperature ultrasonic elastic modulus, thermal expansion and contraction rate, cracking after molding, etc. are measured and evaluated for each refractory material prepared according to the above. Table 1 shows the results.

[Volume specific gravity and porosity (%)]: KS L ISO 5017

The refractory brick sample measuring the dry mass was maintained in a vacuum chamber for 15 minutes, then injected with white kerosene, held for 30 minutes, and then maintained after removing the vacuum for 30 minutes.

[Compressive strength]: KS L ISO 10059

The size of the sample was measured based on a diameter of 50 mm.

[ Hot bending strength]

The strength was measured at a temperature of 800 ° C., which is a refractory site to be solved by the present invention.

[One- sided heating spalling test]

The thermal shock resistance of the sample prepared by the present invention was indexed to the thermal gradient spalling test. In this way, a sample of the sample is prepared with a width of 50 mm, a height of 270 mm, and a width of 30 mm, and is placed in an electric furnace heated to 1600 ° C. for about half the length of the sample for 15 minutes. Thereafter, the mixture was cooled in water for 3 minutes, and then left in air for 12 minutes to check the crack appearance of the sample. By repeating this method several times, the number of Chs in which the sample cracks are generated is recorded and evaluated. In Table 1, the number of sample cracks Ch of Comparative Example 1 was indexed to 100, and the results of other examples were recorded as relative values.

[ Room temperature ultrasonic modulus] :

Ultraman-170 was used as a measuring device, and it was measured by contacting both sides of the sample with an ultrasonic probe. The size of the specimen is 50mm X 50mm X 50mm, and it is subjected to reduction firing to a specific temperature according to the user's needs and then measured at room temperature.

[ Thermal expansion and contraction rate]

The thermal expansion and contraction rate of the refractory is measured using a dilatometer. The size of the specimen is 7 x 7 x 25 mm, and the surface of the sample is polished with sandpaper to smooth the surface.

[ Good appearance after molding]

When the cross-section was cut after compression molding by filling the refractory composition, it was evaluated as bad (X) if the degree of internal cracking was severe, insufficient (△) if there was a fine crack, and good (○) if there was no crack.

[ Well block part pre-deviation and pre-crack occurrence degree]

Samples are prepared with a width of 30 mm, a length of 200 mm, and a width of 20 mm to include the core portion and the well block portion. The well block portion of this sample was immersed in molten steel dissolved in an induction furnace at 1600 ° C for 90 seconds, then taken out, and cooled in water for 15 seconds and 480 seconds in the air. This method was carried out up to 60Ch, and after cross-sectioning of the sample, the sample was dropped before 60Ch (X), if the well block was cracked and dropped after 60Ch (△), and only the crack was cracked after 60Ch. If there is (○) was evaluated.

4 is a cross-sectional view of the odor-resistant refractory material after use, and is a photograph showing the form of penetration and cracking of molten steel. It can be seen that when the molten steel penetrates into the refractory material and causes damage, the well block portion is damaged and eliminated due to the boundary portion to maintain the integrity of the core portion.

division Comparative example
One Comparative example
2 Comparative example
3 Comparative example
4 Comparative example
5 Comparative example
6 Comparative example
7 Example
One Example
2 Specific gravity
2.83 2.92 2.84 2.78 2.88 2.72 2.81 2.88 2.87 Porosity (%)
1.8 2.8 2.5 6.2 1.5 1.9 3.6 2.8 3.1 Compressive strength
(kg / cm ² ) 350 485 410 494 470 450 480 464 442 Bending strength
(kg / cm ² )
at 800 ℃ 130 138 142 128 108 94 131 158 150 Ultrasonic modulus
(GPa)
800 ℃ reduction plasticity 9.6 11.2 10.0 9.1 6.5 7.3 9.0 8.1 7.9 Thermal expansion and contraction rate
(%)
at 800 ℃ 0.58 0.65 0.62 0.52 0.40 0.68 0.53 0.50 0.48 Heat shock index
(One side heating
Spalling) 85 75 88 90 85 60 95 100 95 Appearance after molding
Good degree ○ ○ ○ ○ ○ ○ ○ ○ ○ Well Block Department
Dropout and
Degree of pre-crack △ X X ○ △ X ○ ○ X

As can be seen from Table 1, in the case of Example 1-2 using the composition component and molding method of the present invention, better basic physical property values and hot evaluation (curvature strength, heat shock) than Comparative Example 1-7 that is not Index, etc.).

On the other hand, Comparative Example 1-6 is a case in which any one of the conditions of the present invention is excluded, and the heat-resistant shock characteristics and the like can be seen to be worse than in Examples 1-2.

In addition, Comparative Example 6 is a case in which the content of each composition component of the present invention is out, and it can be seen that the heat-resistant shock characteristics and the flexural strength are significantly worse than in Example 1.

Therefore, as shown in Example 1-2, each of the compositional components suggested in the present invention should be included in an appropriate amount, and have a low elastic modulus, a low thermal expansion and contraction rate, and a high hot bending strength value, thereby improving heat shock resistance through thermal stress relief. You can see that you can expect.

10: odor-resistant refractory body 11: refractory inside (core part)
12: refractory outside (well block portion) 15: refractory inside and outside boundary
20: pipe through 80: cooling gas supply pipe

Claims (10)

The main raw material is composed of 75% to 85% by weight of electrolytic magnesia clinker and 15% to 25% by weight of impression graphite,
0.5 to 3.0 parts by weight of coal-based pitch with a softening point of 200 to 250 ° C. and an average particle size of 40 to 60 μm, based on 100 parts by weight of the main raw material; 0.5 to 5.0 parts by weight of a no-block type phenolic powder binder; Frit 0.5 ~ 5.0 parts by weight having a melting temperature of 750 ~ 950 ℃; And 1.0 to 5.0 parts by weight of aluminum powder,
The electro-melting magnesia clinker is a odorless magnesia car, characterized in that it comprises 10 to 25% of an electro-magnesia clinker having a particle size of 3 to 5 mm and 25 to 35% of an electro-magnesia clinker having a particle size of 1 mm or less. Intrinsic refractory composition.
The composition of claim 1, wherein the noblock-based phenolic powder binder has a residual carbon measured at 800 ° C. and satisfies 40 to 60% by weight.
[3] The composition for a odorless magnesia carbonaceous refractory according to claim 1, wherein the average particle size of the aluminum powder is 10 to 45 mu m.
delete With respect to 100% by weight of the main raw material composed of 75% to 85% of electrolytic magnesia clinker and 15 to 25% by weight of impression graphite, and 100 parts by weight of the main raw material, the softening point is 200 to 250 ° C and the average particle size is 40 to 60%. 0.5 to 3.0 parts by weight of coal-based pitch satisfying µm; 0.5 to 5.0 parts by weight of a no-block type phenolic powder binder; Frit 0.5 ~ 5.0 parts by weight having a melting temperature of 750 ~ 950 ℃; And 1.0 to 5.0 parts by weight of aluminum powder, and the electrolytic magnesia clinker has a weight percent of itself, 10 to 25 percent of electrolytic magnesia clinker having a particle size of 3 to 5 mm, and 25 to 25 percent of electrolytic magnesia clinker having a particle size of 1 mm or less. Preparing a composition comprising 35%;
A step of applying a carbon-based adhesive to the surface after preparing the cylindrical core portion refractory molded product by isostatically pressing and molding the prepared composition into a mold after kneading, and then 0.8-1.6 ton / cm 2;
After fixing the refractory molded article of the core portion to the center of the well block mold, filling the composition for the well block portion and isostatically press-molding it with a force of 1.0 to 1.8 ton / cm 2 to produce a cylindrical deodorized refractory molded article; And
A method of manufacturing a low-odor magnesia carbonaceous refractory material comprising the step of drying the molded article.
The method of claim 5, wherein the drying step,
First drying the molded article in a hot air drying furnace at a temperature of 120 to 180 ° C for 4 to 8 hours; And
A method of manufacturing a low-odor magnesia carbonaceous refractory material comprising the step of secondary drying the molded article at a temperature of 180 to 300 ° C for 12 to 16 hours.
The method of claim 5, wherein in the low-odor refractory material, the fixed carbon content of the core portion refractory material is managed by 5 to 20% by weight higher than the well-block portion.
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