KR20110077050A - Refractory brick for equipment of pre-treating molten iron - Google Patents

Abstract

PURPOSE: Refractory bricks for molten iron pre-treating facility are provided to prevent the temperature of molten iron from being reduced by suppressing the diffusion of heat through a torpedo car or a charging ladle. CONSTITUTION: Refractory bricks for molten iron pre-treating facility includes 84-90 weight% of alumina clinker, 2-5 weight% of silicon carbide, 3-7 weight% of scaly graphite, and 2-4 weight% of kyanite as main components. 1-2 weight% of borosilicate frit and 1-2 weight% of metal silicon powder are further included based on the 100 weight% of the main components. The alumina clinker is thermally treated at temperature between 1300 and 1400 degrees Celsius. The borosilicate frit is based on 60 weight% of silicon oxide, 10 weight% of aluminum oxide, 15 weight% of boron oxide, 5 weight% of calcium oxide, 1 weight% of magnesium oxide, 4 weight% of lead monoxide, and 5 weight% of sodium oxide.

Description

Refractory brick for equipment of pre-treating molten iron}

The present invention relates to a firebrick for a molten iron preliminary treatment plant. In particular, it relates to a refractory brick for molten iron preliminary treatment equipment that can prevent the temperature of the molten iron is lowered by suppressing heat dissipation in crosstalk cars or charging ladles.

Generally, a torpedo car or a charging ladle is provided as a molten iron preliminary treatment facility for charging molten iron in a converter which is a steelmaking process facility. Since these crosstalks or charging ladles store and transport hot molten iron, a fireproof composition such as refractory brick or the like is used for the inner wall.

As refractory bricks applied to the above-mentioned molten iron preliminary treatment facilities, clay fire bricks and alumina fire bricks have been used in recent years, and recently, Alsica (Al ₂ O ₃ -SiC-C) having excellent corrosion resistance and fluorine material is used. It is converted into a quality firebrick and used.

However, the conventional Alsica brick refractory brick (Alsica brick) has a high thermal conductivity because it is manufactured by adding a large amount of graphite and silicon carbide to alumina as a refractory material to ensure corrosion resistance, thermal shock resistance and oxidation resistance. That is, in the conventional al-sicamyl refractory brick, the heat of the molten iron is dissipated to the outside of the cross talk car or the charging ladle through the refractory brick during use, so that the temperature of the molten metal contained in the cross talk car or the charging ladle is sharply lowered.

In addition, when the amount of carbon contained in the graphite is simply reduced for the purpose of suppressing heat dissipation during the manufacture of the alcicamyl refractory brick, there is a disadvantage in that the remaining expandability of the refractory brick is insufficient. That is, there is a problem in that the structural part of the molten iron preliminary treatment facility is opened by opening the wood (or joint) facing the adjacent refractory brick.

The present invention provides a firebrick for a molten iron preliminary treatment plant having low thermal conductivity.

The present invention provides a refractory brick for molten iron preliminary treatment equipment that can prevent the temperature of the molten iron is lowered by suppressing heat dissipation in crosstalk cars or charging ladles.

The firebrick for the molten iron preliminary treatment plant according to an embodiment of the present invention is 84 to 90% by weight of alumina clinker, 2 to 5% by weight of silicon carbide, 3 to 7% by weight of graphite graphite, 2 to 4% by weight of kaiite 1 to 2% by weight of borosilicate frit and 1 to 2% by weight of metal silicon powder are added to 100% by weight of the main component.

The firebrick for the molten iron preliminary treatment plant according to an embodiment of the present invention is formed to have low thermal conductivity by reducing carbon content as well as corrosion resistance, thermal shock resistance, and oxidation resistance. In other words, it is used in the cross-car of the molten iron pre-treatment facilities or the inner wall of the charging ladle to suppress the heat dissipation to the outside of the cross-car or charging ladle in the process of storing or transporting the hot molten iron to reduce the temperature of the molten iron rapidly You can prevent it.

In addition, even when the carbon content of the refractory brick for molten iron preliminary treatment equipment is reduced, the structural stability of the molten iron preliminary treatment equipment can be improved by adding an expandable material such as kaiiteite to maintain the remaining expandability.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like reference numerals in the drawings refer to like elements.

Refractory brick for the molten iron preliminary treatment equipment according to an embodiment of the present invention is 84 to 90% by weight of alumina clinker, 2 to 5% by weight of silicon carbide, 3 to 7% by weight of graphite graphite %, ₂ to 4 wt% of kyanite (Al ₂ O ₃ · SiO ₂ ), and extrapolated 1 to 2 wt% of borosilicate frit and 1 to 2 wt% of metal silicon powder.

That is, it contains 84 to 90% by weight of alumina clinker, 2 to 5% by weight of silicon carbide, 3 to 7% by weight of graphite graphite, and 2 to 4% by weight of kaiiteite, based on 100% by weight of the main component (based on ) 1 to 2% by weight of borosilicate frit and 1 to 2% by weight of metal silicon powder are added.

Refractory brick for the molten iron preliminary treatment plant according to an embodiment of the present invention is an Alsica (Al ₂ O ₃ -SiC-C) quality refractory brick mainly composed of aluminum (Al), silicon (Si), carbon (C) Is formed.

In general, alumina refractory bricks are susceptible to thermal shock, and slag is easily infiltrated and applied to a load where surface cracks or inclusions are present, so that the surface is gradually peeled off, that is, structural spalling easily occurs. To reinforce these shortcomings, graphite having high thermal conductivity and low wettability against slag was combined with alumina to form an alumina-carbon refractory brick.

However, alumina-carbon refractory bricks have a disadvantage in that carbon is easily oxidized, so to reinforce them, silicon carbide serving as an antioxidant at high temperature, metal silicon powder and low melting point material serving as an antioxidant at low temperature, frit) powder was mixed to prepare alcicasyl refractory brick with various characteristics.

Looking at each component included in the refractory brick according to an embodiment of the present invention.

Alumina clinker: 84-90 wt%

Alumina clinker is a refractory material that increases corrosion resistance to slag or molten iron. If the amount of the alumina clinker is less than 84% by weight, the corrosion resistance is lowered. In an embodiment of the present invention, in order to improve the corrosion resistance among the alumina clinker, an alumina clinker heat-treated at a temperature range of 1300 to 1400 ° C. was used by an electric melting method. That is, it is possible to improve the corrosion resistance by increasing the purity of the alumina through the heat treatment, and by increasing the crystal size of the alumina clinker.

Silicon Carbide: 2-5 wt%

Silicon carbide is a material for enhancing oxidation resistance, and is added to correspond to the amount of carbon added, and is preferably contained in a composition ratio of 2 to 5% by weight. At this time, when using a silicon carbide fine powder having a particle size of 74㎛ or less as in one embodiment of the present invention can improve the oxidation resistance.

Impression graphite: 3-7 wt%

Impression graphite is a material that improves the thermal shock resistance and infiltration resistance of slag of Alsicasil refractory brick, and is less than 3% by weight, which is not preferable because the thermal shock resistance is lowered. The heat increases, which causes a large decrease in the molten iron temperature, which is undesirable.

Cayanite: 2 to 4 wt%

Cayanite is an expandable material, and is one of the silimiteite minerals and is composed of Al ₂ O ₃ · SiO ₂ . It exhibits a significant endothermic reaction at 1390-1420 ° C., and this change (caineite → silimanite → mullite + silicon oxide) causes very large permanent expansion.

When the kaiite is added in less than 2% by weight, the remaining expandability of the alciccyl refractory brick is insufficient, and structural stability of the refractory brick is decreased. On the contrary, if it is added in excess of 4% by weight, the remaining expandability may become so large that the joints between adjacent refractory bricks may be damaged.

Borosilicate frit: 1-2 wt%

Borosilicate frit is a material having a composition as shown in Table 1 below, and melted at a low temperature to cover the surface of the surrounding carbon particles to prevent oxidation of carbon from the outside atmosphere. When less than 1% by weight is added, the antioxidant effect is insufficient, and when more than 3% by weight is added, oxidation resistance is enhanced, but corrosion resistance is lowered, which is not preferable.

TABLE 1

Chemical composition SiO ₂ Al ₂ O ₃ B ₂ O ₃ CaO MgO PbO Na ₂ O Content (% by weight) 60 10 15 5 One 4 5

As shown in Table 1 above, borosilicate frit has 60% by weight of silicon oxide (SiO ₂ ), 10% by weight of aluminum oxide (Al ₂ O ₃ ), 15% by weight of boron oxide (B ₂ O ₃ ), calcium oxide It is composed of 5% by weight of (CaO), 1% by weight of magnesium oxide (MgO), 4% by weight of lead monoxide (PbO), and 5% by weight of sodium oxide (Na ₂ O).

Metallic silicon powder: 1-2 wt%

Metallic silicon powder is oxidized before carbon or reacts with carbon to become silicon carbide, and then oxidizes to precipitate carbon to give oxidation resistance, and less than 1% by weight of the antioxidant effect is insufficient and exceeds 2% by weight. If it does, corrosion resistance falls and it is unpreferable.

Hereinafter, the firebrick for the molten iron preliminary treatment facility according to an embodiment of the present invention will be described in more detail with reference to various embodiments of the experiment.

Addition of 1-2% by weight of borosilicate frit and 1-2% by weight of metal silica powder by extrapolation as an antioxidant to the main Alsica component of 100% by weight of alumina clinker, silicon carbide, impression graphite, and chianyite. After the addition of 4% by weight of a phenol resin (liquid phenol resin) as a binder by extrapolation to prepare a specimen of size 25 × 25 × 150 mm at a pressure of 1200 kg / ㎠ after pressure kneading. (In this case, 'extrapolated' means 'based on the main component of 100% by weight.') After drying the prepared specimen at a temperature of about 250 ℃, by evaluating the residual line change rate and erosion resistance at each temperature It is shown as [Table 2] below.

TABLE 2

Example Comparative example One 2 3 One 2 3 4 5 Alumina Clinker 86 89 90 87 92 90 85 85 Silicon Carbide 5 3 3 6 One 4 5 5 Impression 7 5 3 7 3 2 9 5 Cayenne Knight 2 3 4 0 4 4 One 5 Metal silicon +1 +1 +2 +1 +1 +1 +1 +1 Borosilicate frit +2 +1 +2 +2 +2 +2 +2 +2 Liquid Phenolic Resin +4 +4 +4 +4 +4 +4 +4 +4 Residual Line Change (%)
(1400 ℃ x 3 hours) +0.6 +0.5 +0.4 -0.1 -0.15 -0.1 +0.1 +0.9 Thermal Conductivity (W / mK) 10 8 7 8 7 6 15 8 Erosion Index 80 90 100 96 120 130 90 94 Oxidation resistance ◎ ◎ ○ ◎ × ◎ ◎ ◎ Spalling resistance ◎ ◎ ○ ◎ × × ◎ ○

In Table 2, the measurement of the residual line change rate was measured by using an electric furnace to increase the temperature to 5 ° C. per minute up to 1400 ° C. for 3 hours, and then cooled and measuring the length of the specimen. The length change and the length change when heat treated at 1400 ° C. were measured, and the changed length deviation was calculated as a percentage by dividing the specimen length by drying.

In addition, the measurement test of the erosion index was carried out for 120 minutes at a temperature of 1500 ℃ using an induction furnace, and slag was replaced every 30 minutes. At this time, a molten iron and a crosstalk slag were used as an erosion agent.

In the oxidation resistance test, the specimen was placed in an electric furnace and heat-treated at 1400 ° C. for 3 hours, and the thickness of the oxide layer was compared and judged. The thermal conductivity test was a result measured by a laser flash method.

On the other hand, the spalling resistance test is a result of observing the appearance of the specimen after 8 times to put the specimen in an electric furnace maintained at 1300 ℃, quenched and maintained for 30 minutes and then taken out to air-cooled.

In Comparative Example 1, the addition amount of the Cayanite, which is an expandable substance, is 0% by weight, and may be easily dropped when installed in the molten iron preliminary treatment facility due to the lack of remaining expandability. That is, there is a problem in structural stability. On the other hand, in Comparative Example 5, the addition amount of the expandable kaiite is 5% by weight, so excessively added that the remaining expandability is so large that the joints between adjacent refractory bricks may be damaged.

In Comparative Example 2, the content of silicon carbide is 1% by weight, and the oxidation resistance is insufficient.

On the other hand, with respect to the content of the impression graphite which greatly influences the content of carbon, Comparative Example 3 contains less than 2% by weight of the impression graphite, which is insufficient in corrosion resistance or poor in spalling resistance. In addition, Comparative Example 4 is excessively contained in 9% by weight of the graphite, the high thermal conductivity when applied to cross-talk or charging ladle containing molten iron, can not suppress the heat of dissipation can be drastically lower the temperature of the molten iron.

Examples 1, 2 and 3 are not only alumina clinker, silicon carbide, impression graphite, and kaiite which are main components of Alsica refractory bricks, but also extrapolated metal silicon powder and borosilicate frit according to one embodiment of the present invention. As it exists in the addition amount range, it can be confirmed that residual expandability and thermal conductivity exist in an appropriate range, without a big fall of erosion resistance.

As described above, the refractory brick for molten iron preliminary treatment equipment according to an embodiment of the present invention is formed to have corrosion resistance, thermal shock resistance, oxidation resistance, and low thermal conductivity by controlling the composition ratio of each component in an appropriate range. In other words, instead of increasing the composition ratio of alumina clinker, the composition ratio of silicon carbide and impression graphite related to thermal conductivity was lowered. Therefore, it is used in the inner wall of the cross-loading or charging ladle of the molten iron preliminary treatment equipment to suppress the heat dissipation to the outside of the cross-loading or charging ladle during the storage or transportation of hot molten iron, thereby rapidly decreasing the temperature of the molten iron. You can prevent it.

In addition, even when the carbon content of the refractory brick for molten iron preliminary treatment equipment is reduced, the structural stability of the molten iron preliminary treatment equipment can be improved by adding an expandable material such as kaiiteite to maintain the remaining expandability.

As mentioned above, although this invention was demonstrated with reference to the above-mentioned Example, this invention is not limited to this, It is limited by the following claims. Therefore, it will be apparent to those skilled in the art that the present invention may be variously modified and modified without departing from the technical spirit of the following claims.

Claims (4)

84 to 90% by weight of alumina clinker, 2 to 5% by weight of silicon carbide, 3 to 7% by weight of graphite graphite, and 2 to 4% by weight of kaiiteite as main components, and borosilicate frit 1 to 2 based on 100% by weight of the main component. A firebrick for a molten iron preliminary treatment equipment to which a weight% and 1 to 2 weight% of metal silicon powder are added. The method according to claim 1, The alumina clinker is, Refractory brick for molten iron preliminary treatment equipment which is heat-treated in the temperature range of 1300 ~ 1400 ℃ by the electrofusion method. The method according to claim 1, The silicon carbide, Refractory brick for molten iron preliminary treatment facilities with a particle size of 74㎛ or less. The method according to claim 1, The borosilicate frit, 60% by weight of silicon oxide (SiO ₂ ), 10% by weight of aluminum oxide (Al ₂ O ₃ ), 15% by weight of boron oxide (B ₂ O ₃ ), 5% by weight of calcium oxide (CaO), magnesium oxide (MgO) 1 A refractory brick for a molten iron preliminary treatment plant composed of wt%, lead monoxide (PbO) 4 wt%, sodium oxide (Na ₂ O) 5 wt%.