KR101323295B1 - fireproof composite - Google Patents

Abstract

The present invention relates to a refractory composition capable of recycling high melting point magnesia (MgO) -silica (SiO ₂ ) -based by-products generated in an electric furnace. It is characterized by. At this time, the pulverized product of the slag may be contained 85 to 88% by weight based on the total weight of the refractory composition. This makes it possible to efficiently recycle slag generated in the furnace.

Description

Fireproof composite

The present invention relates to a fire resistant composition, and more particularly, to a fire resistant composition capable of recycling high melting point magnesia (MgO) -silica (SiO ₂ ) -based by-products generated in an electric furnace.

Blast furnace operation is a work to produce molten iron by injecting high temperature hot air through the tuyere installed in the lower part of the furnace such as iron ore and coke in the furnace. In this process, iron ore and coke charged into the blast furnace are lowered to the lower part of the furnace as the coke burns and the iron ore is reduced and melted. The gas generated during the melt reduction process of ascends to be discharged to the upper part of the blast furnace, and is damaged by the refractory smoke installed inside the blast furnace furnace by the chemical erosion reaction generated at the contact with the furnace refractory lead.

In addition, because the furnace temperature distribution from the bottom of the blast furnace to the top of the blast furnace is maintained at a high temperature from 2200 ℃ to 400 ℃ under high pressure conditions, it is necessary to specifically configure the blast furnace body structure to withstand such high temperatures. In order to meet these objectives, the blast furnace body structure builds a steel bar made of iron plates on the outside of the furnace body and builds a fire-resistant lead that can withstand high temperatures inside. As the above-mentioned fire retardant and itself alone cannot sufficiently cope with the high temperature in the blast furnace, a cooling panel or a stave, which is a cooling device capable of cooling the fire retardant between the fire retardant and between, is installed to improve the cooling ability with the fire retardant. To reduce the damage to the flame and to extend the life of the blast furnace.

On the other hand, as the thickness of the lead becomes thin due to an increase in the wear loss with the refractory smoke installed in the blast furnace furnace, the heat load by the high-temperature gas and the charge in the furnace is increased, and the furnace shell is avoided despite the cooling of the furnace by the furnace cooling cooling device. It causes one of the factors that shorten the life of the blast furnace by causing redness and cracks on the surface.

Therefore, in order to extend the service life of the blast furnace operation period, it is essential to repair the flame retardant and the damaged part installed inside the furnace body. For this purpose, the indentation material, which is an irregular refractory material, is pressed into the damaged part. At this time, the press-fitting material used is a refractory composition made of alumina refractory raw material, which is mostly imported from foreign countries, and thus the raw material price fluctuates severely and there is a difficulty in supply and demand.

On the other hand, stainless steel is produced by melting molten iron and ferroalloy in an arc furnace to arc steel, and refining the molten steel in a refining furnace. By-products such as dust and slag are produced in this series of processes. In the case of the double slag, since there is no suitable use, most of the landfill is disposed of, and thus there is a problem that the environment is polluted. Therefore, there is a need for a treatment method that can be used for various purposes by recycling slag generated in manufacturing stainless steel.

KR 0450222 B1 KR 2000-42142 A

The present invention provides a fire resistant composition that can recycle slag generated during the production of stainless steel.

The present invention provides a fire resistant composition capable of preventing environmental pollution.

The present invention provides a fire resistant composition that can reduce the maintenance cost of steelmaking facilities.

The fire resistant composition which concerns on embodiment of this invention is characterized by using the grind | pulverized material of the slag produced | generated in the electric furnace as a main raw material of the said fireproof composition as a fireproof composition. At this time, the pulverized product of the slag may be contained 85 to 88% by weight based on the total weight of the refractory composition. This makes it possible to efficiently recycle slag generated in the furnace.

The slag pulverized product may contain 80% by weight or more of MgO and SiO _{2 based} on the total weight of the pulverized product. The higher the content of MgO and SiO ₂ is, the higher the melting point is, thus being able to sufficiently serve as a fire resistant aggregate.

In addition, the particle size of the pulverized product is 3 mm or less to help improve roughness and workability.

In particular, the refractory composition is an auxiliary material, based on the total weight of the refractory composition 10 to 12% by weight of the alumina (Al ₂ O ₃ ) powder, 1 to 3% by weight of silica (SiO ₂ ) flower and sodium silicate (Na ₂ O- By further including 1 to 2% by weight of SiO ₂ ), the workability, roughness and wear resistance of the fire resistant composition can be improved efficiently.

The fire resistant composition according to the embodiment of the present invention can obtain a fire resistant composition excellent in workability, plastic strength and hot strength by recycling slag of high melting point generated in an electric furnace during the process of manufacturing Fe-Ni stainless steel. Accordingly, by using the slag generated in the electric furnace as the main raw material of the water-based indenting material for eliminating the local heating of the blast furnace furnace, it is possible to prevent the environmental pollution that may be caused by the disposal of the slag. In addition, the cost of purchasing the raw material of the fire resistant composition can also be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know.

Stainless steel is manufactured by melting molten iron and ferroalloy with arc heat in an electric furnace to make molten steel, and refining the molten steel in a refining furnace. By-products such as slag are produced in the stainless steel manufacturing process, and the composition of the slag depends on the type of ferroalloy added. For example, in the process of manufacturing Fe-Ni stainless steel, magnesia (MgO) -silica (SiO ₂ ) -based slag is produced, which is mostly disposed of through landfill. However, such magnesia-silica-based slag contains a large amount of SiO ₂ and MgO, and has a high melting point characteristic, and thus, development of various applications that can utilize such characteristics is required. Thus, in the embodiment of the present invention, magnesia-silica-based slag is used as a composition of the indentation material that is a refractory material used to repair the blast furnace wall having a high temperature working environment.

Refractory composition according to an embodiment of the present invention is a magnesia-silica-based slag produced in the electric furnace for manufacturing Fe-Ni stainless steel as a main raw material, alumina (Al ₂ O ₃ ) powder, silica flour (Silica flour, SiO ₂ ) And sodium silicate as an auxiliary ingredient. The fire resistant composition thus constructed is mixed with water (water) and used as a press-fitting material for repairing blast furnace walls and the like.

Magnesium (MgO) -silica (SiO ₂ ) -based slag is generated in an electric furnace when manufacturing Fe-Ni used as an alloying material of stainless steel, and has a composition as shown in Table 1 below.

division SiO ₂ MgO Al ₂ O ₃ CaO T.Fe Ni MgO-SiO ₂ Slag 54 35 2 0.01 <5 0.002

As shown in Table 1, MgO-SiO ₂ -based slag contains a large amount of SiO ₂ and MgO, and contains a small amount of impurities such as Al ₂ O ₃ , CaO, T.Fe, and Ni. It has a high melting point and is very suitable for acting as a fire resistant aggregate. Therefore, in the embodiment of the present invention, the slag of high melting point generated in the electric furnace can be utilized as the main raw material of the amorphous indentation material as a fireproof composition. Therefore, magnesia-silica-based slag is used as the main raw material of the indentation material instead of alumina or alumina-silica clinker, which was previously used as the main raw material of the blast furnace body indenting material.

The slag generated in the electric furnace is used as a main raw material of the press-fitting material by crushing and then separating the particles. At this time, in order for the slag to be used as the main raw material of the indentation material SiO ₂ And MgO is preferably contained at least 80% by weight based on the total weight of the pulverized product. If the content of SiO ₂ and MgO is less than the indicated range, the melting point is lowered, there is a problem that the performance as a refractory aggregate is lowered. Although the properties of the pulverized product are not particularly restricted, the particle size is preferably 3 mm or less in consideration of workability.

Magnesia-silica slag, ie pulverized, is used in an amount of 85 to 88% by weight based on the total weight of the indenting material. Since the press-fitting material is used to repair the blast furnace furnace, etc., it should be excellent in workability, roughness and wear resistance. Therefore, in the embodiment of the present invention by using the crushed slag to the maximum within the range that does not lower such characteristics, the generation of environmental pollution by slag landfill disposal is suppressed, and the cost of purchasing the raw material is reduced. In the case where the crushed product of slag is used in an excessively larger range than the suggested range, there is a problem in that workability and roughness deteriorate, and wear resistance also decreases. In addition, in the case where the pulverized product is used in less than the suggested range, there is a problem in that the slag is used as a main raw material of the press-fitting material, as well as the workability, roughness and abrasion resistance, which do not correspond to the purpose of the present invention.

Subsidiary materials of the indentation material are alumina powder, silica flower and sodium silicate. The press-fitting material contains 10 to 12% by weight of alumina powder, 1 to 3% by weight of silica flower, and 1 to 2% by weight of sodium silicate. The alumina powder is used to impart fluidity to the indentation material and to increase the bonding strength at high temperature. When the amount of the alumina powder is used in a smaller amount than the suggested range, the alumina powder is deteriorated in the formability due to the lack of the compressibility. If the amount is used, there is a problem that the amount of magnesia-silica slag that is the main raw material is reduced. In addition, the silica flower is a material in an ultra fine powder state, and is a component added to maintain the bonding strength in the intermediate temperature range of about 600 to 1000 ° C. with the fluidity and dry strength of the indentation material. However, when the content of the silica flower is less than the suggested range, the fluidity imparting effect and the strength enhancing effect are weak, and the workability and durability are deteriorated. When the content is more than the suggested range, the fluidity decreases due to the increase of ultra fine powder. There is a problem. In addition, sodium silicate serves as a thermosetting binder. When the indentation material is pressed into the blast furnace furnace body, the indentation material is hardened by the high heat inside the blast furnace, thereby contributing to the formation of a wall (rough wall). When the content of sodium silicate is less than the suggested range, the roughness deteriorates and the repair of the furnace body is difficult. On the other hand, when the content of the sodium silicate is more than the suggested range, the hot property of the refractory is deteriorated and durability is deteriorated.

Therefore, it is necessary to maximize the fluidity, roughness, durability, etc. by using the content of the main raw materials and the subsidiary materials adjusted appropriately within the range.

Hereinafter, look at the experimental results for confirming whether the refractory composition according to an embodiment of the present invention is suitable as a repair material such as blast furnace having a high temperature process environment.

To prepare a fire resistant composition as shown in Table 2 below. Then, after adding 12% water of the total weight of the composition to each refractory composition, a specimen of 40 × 40 × 160 mm size was prepared through molding, curing and drying.

Example Comparative Example One 2 3 One 2 3 4 5 MgO-SiO ₂ Slag 85 85 88 90 85 85 85 85 Al ₂ O ₃ 11 12 10 7 10 13.5 12.5 10 SiO ₂ 3 One One 2 4 0.5 2 2 Na ₂ O-SiO ₂ One 2 One One One One 0.5 3 Fluidity (mm) 180 180 170 130 140 140 160 160 Breaking strength
(℃ / hour) 110/24 146 150 150 140 150 75 60 165 800/3 154 180 160 150 160 110 60 165 1000/3 130 140 140 100 170 78 100 140 Hot bending strength (1100 ℃, ㎏ / ㎠) 83 70 60 30 20 18 13 5

In evaluating the characteristics of the press-fitting material, the important physical properties are the fluidity to evaluate the roughness and workability of the press-fitting material when the press-fitting material is pressed into the blast furnace body, and the hot bending strength to evaluate the wear resistance that can withstand the heat after the roughing wall.

The fluidity test for evaluating the workability of the refractory material was carried out using the prepared specimen. The flow rate evaluation test was performed by measuring the spreadability (diameter) of the material after 15 vibrations using a flow tap.

In addition, hot bending strength was measured using a specimen, and hot bending strength measurement was performed using a three-point bending strength test method at a temperature of 1100 ° C.

As a result of measuring the flow rate, according to Table 2, in Examples 1 to 3, in which the refractory composition had a content within the range, the flow rate was measured as high as about 170 to 180 mm, whereas the content of the composition was outside the range indicated. In the case of Comparative Examples 1 to 5, it can be seen that the flow rate was measured to be relatively low, about 130 to 160 mm. In particular, in Comparative Example 1 in which the pulverized product of slag, which is the main raw material, was contained more than the indicated range, and the alumina powder contained less than the indicated range, the flow rate was measured to be too low. It is judged to have.

In addition, as a result of measuring the hot bending strength, according to [Table 2], in the case of Examples 1 to 3, in which the refractory composition had a content within the range, the hot bending strength was measured as high as about 60 to 80 kg / cm 2, but the content of the composition In the case of Comparative Examples 1 to 5 outside this suggested range, the hot bending strength was measured to be relatively low at 5 to 30 kg / cm 2. That is, when the composition of the indentation material is out of the suggested range it can be seen that the wear resistance that can withstand hot after the rough wall is significantly reduced.

In Comparative Example 1, the pulverized crushed magnesia-silica-based slag generated in the Fe-Ni manufacturing furnace was added in excess of the range shown, and the alumina powder as an auxiliary material was added in less than the range shown. Accordingly, in Comparative Example 1, the fluidity and the hot bending strength were lowered.

And Comparative Examples 2 and 3 were contained such that the silica flower was out of the range shown. Comparative Example 2 containing silica flowers in excess of the indicated ranges decreased fluidity and hot bending strength, and in Comparative Example 3 in which silica flowers contained less than the indicated ranges, dry strength (break strength at 110 ° C.) and hot bending strength Was lowered.

In addition, for Comparative Examples 4 and 5, sodium silicate was contained so as to deviate from the range shown. In Comparative Example 4, the dry strength and the plastic strength (bending strength at 800 ° C.) were lowered. In Comparative Example 5, the dry strength and the plastic strength were high, but the hot bending strength was greatly reduced due to excessive liquid phase generation.

Although the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Therefore, the scope of the present invention should not be limited by the described embodiments, but should be defined by the appended claims and equivalents thereof.

Claims (5)

As a fireproof composition,
The pulverized product of the slag generated in the electric furnace is 85 to 88% by weight, 10 to 12% by weight of alumina (Al ₂ O ₃ ) powder, 1 to 3% by weight of silica (SiO ₂ ) flower and Sodium silicate (Na ₂ O-SiO ₂ ) It contains 1 to 2% by weight,
The slag pulverized product contains 80% by weight or more of MgO and SiO _{2 based} on the total weight of the pulverized product. delete delete The method according to claim 1,
The particle size of the pulverized product is 3 mm or less. delete