KR100805619B1 - Refractory brick determinable the remaining amount of the refractory - Google Patents

Abstract

The present invention relates to a refractory remaining amount determination lead installed in the refractory so as to determine the degree to which the refractory to be constructed to protect the steel bar for ironworks is melted by a high temperature melt, 80 ~ 85wt% MgO aggregate, 8 to 12 wt% of carbon, a predetermined structure composed of the remaining binders and metal additives, 20 to 22 wt% of SiO ₂ and 43 to 45 wt% of PbO as main components, and 5 to 7 wt% of Na ₂ O and , A coating layer formed by applying a coating agent containing 7 ~ 9wt% Li ₂ O to the outer surface of the structure, to prevent the oxidation of carbon in the lead constituting the MgO aggregate and carbon as a main component By applying the coating agent to the surface of the edible so as to have a lower erosion index than the erosion index of the refractory to be installed on the inner surface of the bark so that the remaining amount of the refractory remaining in the ladle in the hot state To make the determination may contribute to reduction nojaewonga and operation stability.

Coating layer, erosion index, coating agent, metal additive

Description

Refractory brick determinable the remaining amount of the refractory}

1 is a cross-sectional view showing a state in which the refractories for the refractory residual amount determination lead according to the present invention is constructed.

2 is a cross-sectional view of the lead for the refractory remaining amount determination according to the present invention;

3 is a view showing an embodiment in which the residual amount of the refractory is determined by the lead for the refractory residual amount determination according to the present invention.

<Description of Symbols for Major Parts of Drawings>

10: scab

20: refractory

40: lead for determination of refractory residual amount

50: coating agent

The present invention relates to a refractory remaining amount determination lead installed in the refractory so as to determine the residual amount of the refractory material which is constructed to protect the iron bar from high temperature molten steel, and more specifically, the refractory body which is constructed inside the bark. It relates to a refractory residual amount determination lead that can determine the residual amount of the refractory to grasp the degree of melting by the high temperature molten steel to induce the safe operation of the steelmaking process.

In general, a vessel such as a ladle used in a steel mill that handles a hot melt is used to form a refractory structure or an amorphous refractory body inside a barbed structure of a predetermined shape to protect the barbed structure from the hot melt. The orthogonal refractory or amorphous refractory body that is constructed inside the shell structure is melted because it is in direct contact with hot molten iron or molten steel.

At this time, in order to improve the durability of the steelworks container, in particular, the steel structure, as described above, the residual amount of the fixed refractory or amorphous refractory melted by hot molten iron or molten steel is determined, and if the residual amount of the refractory is small, repair it. Repair work is performed. It is very important not only for cost reduction but also for stable operation such as prevention of molten steel, in the repair work of such refractory.

In particular, the ladle of the steel mill is in the form of irregular refractory flows into the steel shell structure, and is inherent to prevent the risk of large accidents during operation. Therefore, it is very important to accurately determine the remaining amount of the refractory during use and to replace the refractory at the appropriate time. Such residual amount of refractory material is visually determined in the hot state maintained at high temperature, or the residual amount is determined after boring the remaining refractory substance in the cold state maintained at normal temperature.

However, while visual judgment can be performed in a short time, measurement errors are likely to occur depending on the skill and operation of the operator, and as a result, error measurement of the residual amount can cause a risk of large accident in operation. Residual amount determination in the cold state has a problem that takes a lot of time.

Conventionally, a technique is known in which a plurality of steel pipes of different lengths are inserted into a refractory to determine a residual amount of refractory material, and then the residual thickness of the refractory is determined by the number of pipes exposed according to the erosion degree of the refractory material. However, this technique has a problem in that the determination efficiency is lowered if the erosion rate of the pipe by the hot melt is equal to or greater than that of the refractory. In addition, when the refractory surface is coated with remnants of molten steel now or the same, the pipe and the refractory form the same height, so it is difficult to observe the degree of exposure of the pipe visually in the hot state. When the steel pipe is melted by the hot melt, the remaining amount of the refractory material cannot be determined accurately.

Recently, a technique for determining the remaining amount of the refractory by determining the remaining amount of the refractory by using an electric control system or by detecting the temperature of the refractory by using a thermocouple is known, but the accuracy of the measurement temperature and the fastener of the thermocouple Risks such as molten steel outflow are caused. In addition, there is a problem that excessive cost is required to make such a technique practical in a facility moving with a ladle.                         

On the other hand, there is a known technique for determining the residual amount of the refractory by using a ceramic ball, the ceramic has a problem that the toughness and brittleness is weak while the corrosion resistance is good. That is, the ceramic ball is easily broken under a high temperature atmosphere of about 1300 ° C., and as a result, the residual amount of the refractory material cannot be determined.

The present invention has been made in order to solve the conventional problems as described above, to determine the extent to which the refractory to be constructed to protect the iron shell is melted by the high temperature melt and to repair the excessive molten portion in a timely manner to repair the molten steel and It is an object of the present invention to provide a refractory remaining amount determination lead that can be easily installed in the refractory so as to prevent such a large accident.

In order to achieve the above object, according to the present invention, the refractory remaining amount determination lead installed in the refractory is 80 ~ to determine the degree to which the refractory to be constructed to protect the iron bar for steelworks is melted by a high temperature melt 80 ~ It is composed of 85 wt% MgO aggregate, 8 to 12 wt% carbon, a predetermined structure composed of remaining binder and metal additive, and 20 to 22 wt% SiO ₂ and 43 to 45 wt% PbO as main components. It is characterized by consisting of a coating layer formed by applying a coating agent containing% Na ₂ O and 7 ~ 9wt% Li ₂ O on the outer surface of the structure.

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention.

First, it is preferable that the lead 40 for refractory residual amount determination according to the present invention has a relatively small erosion index as compared with the erosion index of the refractory 20 to measure the residual amount. That is, when the erosion index of the residual amount determination edge 40 is kept relatively smaller than the erosion index of the refractory 20, as the erosion of the refractory 20 is advanced, the residual amount determination edge 40 is As shown in FIG. 3, the outside of the slag and molten steel coated on the surface of the eroded refractory 20-1 protrudes to the outside so that the field operator can visually observe in a hot state.

In addition, the lead 40 for refractory residual amount determination according to the present invention should have an expansion ratio similar to that of the refractory 20 in a hot state. This is to prevent the spalling phenomenon due to the difference in thermal expansion rate.

Currently, the refractory 20 used in ladles or the like is composed of alumina-spinel or alumina-magnesia refractory, and thus has excellent corrosion resistance to molten steel 30 accommodated in ladles or the like. That is, the erosion index of this refractory 20 is very small, about 0.6mm. Therefore, the erosion index of the lead 40 for refractory residual amount determination according to the present invention should be smaller than the erosion index of the refractory 20.

In order to satisfy this problem, the lead 40 for refractory residual amount determination according to the present invention is a structure 40-1 having a predetermined shape including MgO aggregate having good corrosion resistance to molten steel as a main component and carbon as an auxiliary component. Is produced. At this time, a coating agent for preventing the oxidation of carbon is applied to the outer surface of the structure 40-1 to form a coating layer 50.

That is, according to the present invention, the structure 40-1 of the refractory remaining amount determination lead 40 has a main component of 80 to 85 wt% MgO aggregate and 8 to 12 wt% carbon. MgO aggregate, which is a main raw material, has excellent corrosion resistance to molten steel, and is used in combination with molten MgO aggregate having a relatively small grain boundary and sintered MgO aggregate having a relatively large grain boundary.

When the melt of the low melting compound composed of SiO ₂ , CaO, etc. in the slag penetrates into the grain boundaries of the sintered MgO aggregate, when the dissolved amount of the MgO component in the melt increases, the grain boundaries of the sintered MgO aggregate are loosened, and as a result, the sintered MgO aggregate The grains of effluent flow into the slag and erosion occurs. On the contrary, the melt of the low melting compound composed of SiO ₂ , CaO and the like in the slag is hard to penetrate into the grain boundaries of the molten MgO aggregate.

In general, the melting loss of MgO aggregate is proportional to the slag invading the grain boundaries between MgO aggregates and the reaction rate, so that molten MgO aggregates with relatively high bond strength of grain boundaries in the hot and dense state are produced by slag compared with sintered MgO aggregates. Excellent loss of contents.

Therefore, in order to improve the corrosion resistance of the structure 40-1 of the lead 40 for refractory residual amount determination according to the present invention, it is important to properly adjust the mixing ratio of the molten MgO aggregate and the sintered MgO aggregate. That is, the MgO aggregate constituting the structure 40-1 of the refractory remaining amount determination lead 40 includes 85 to 90 wt% of molten MgO aggregate, and the rest is made of sintered MgO aggregate. At this time, if the addition amount of the molten MgO aggregate is less than 85wt%, the corrosion resistance is lowered when the structure 40-1 contacts the molten steel, whereas if it is 90wt% or more, the bonding of the matrix of the crystal structure of the structure 40-1 is weak. Become.

On the other hand, carbon has properties of relatively low wettability to molten steel and slag, relatively high thermal conductivity, and relatively low thermal expansion rate. For example, the thermal conductivity of carbon measured at a temperature of 1000 ° C. is 0.15, while the thermal conductivity of Al ₂ O ₃ is 0.015, and the thermal conductivity of MgO is 0.017. In particular, carbon is used as a main raw material for improving the corrosion resistance of the material because it improves the resistance to thermal shock.

Therefore, carbon is added to the MgO aggregate in order to improve the corrosion resistance of the refractory residual amount lead 40, wherein the amount of carbon added is limited to 8 to 12wt%. If the added amount of carbon is 8 wt% or less, the corrosion resistance to molten steel is lowered, while if it is 12 wt% or more, the consumption by oxidation of carbon increases, making it difficult to achieve the corrosion resistance to be achieved in the present invention.

On the other hand, when carbon is oxidized by contact with oxygen during the temperature increase operation or during use, the structure of the crystal structure is weakened, and thus has the disadvantage of deteriorating the physical properties of the material during use. In particular, when the carbon component is in contact with the atmosphere while the ladle and spheres are open, the carbon combines with oxygen (O ₂ ) in the atmosphere to volatilize to a CO or CO ₂ state, resulting in weakening of the structure of the crystal structure.

Therefore, according to the present invention, metal additives such as Al, Si, and Mg are added to prevent oxidation of carbon as described above. However, when the addition amount of such a metal additive is relatively large, since the erosion of the lead 40 is accelerated, the addition amount is strictly removed.

In addition, according to the present invention, in order to prevent the fragility of the lead 40 by oxidation of carbon as described above, while minimizing the amount of carbon added, the anti-oxidant coating agent is applied to the surface of the lead. The coating agent contains SiO ₂ , PbO and B ₂ O ₃ as main components. The coating agent applied to the surface of the ducts proceeds to semi-melt glass by the applied heat, and as a result, the carbon located inside the coating agent is prevented from contacting the atmosphere.

On the other hand, since the carbon constituting the lead 40 starts to oxidize at about 700 ° C, it is preferable to lower the melting point of the coating agent. This is because the substantial decrease in the physical properties of the lead 40 for refractory residual amount determination caused by the loss of carbon due to oxidation occurs on the back surface of the lead 40 during operation, so that the coating agent before 700 ° C. at which the oxidation of carbon starts. This is because it must be kept in the glass state.

And in order to lower melting | fusing point of a coating agent, basic flux is added. In the basic flux, the amount of soft fluxes such as K ₂ O, Na ₂ O, Li ₂ O and PbO increases, while the amount of kaolin (Al ₂ O ₃ ) and silica (SiO ₂ ) having a high melting point is increased. It is important to reduce. In addition, it is preferable not to add hard flux such as MgO, BaO and CaO, which are weak at low temperatures, or to add a small amount if necessary.

Hereinafter, the operation of the lead for the refractory residual amount determination according to the present invention will be described.

Table 1 below shows the melting temperature according to the composition of the coating agent to be applied to the surface.

TABLE 1

Example Comparative example One 2 3 One 2 3 4 5 Al ₂ O ₃ 2 2 2 2 2 2 2 2 SiO ₂ 22 20 20 20 30 30 40 40 PbO 43 45 45 35 25 35 15 25 B ₂ O ₃ 5 5 5 5 5 5 5 5 K ₂ O 3 3 3 3 3 3 3 3 Na ₂ O 6 8 6 8 8 8 8 8 CaO 8 6 6 16 16 6 16 6 Li ₂ O 6 8 8 8 8 8 8 8 P ₂ O ₅ 5 3 5 3 3 3 3 3 Melting temperature (℃) 675 650 632 973 1100 714 1232 826

As shown in Table 1 above, the melting temperature of the coating agent consisting of the components of Example 3 was the lowest in the components of the coating agent applied to the lead and the surface. That is, in Example 3, the content of SiO ₂ and CaO, which are high melting point compositions, is reduced, and 6 wt% of Na ₂ O, which is a soft flux, falls within the reference range of 5 to 7 wt%, and 7 to 9 wt% of Li ₂ O. Each was added at 8 wt% in the range. In addition, in the coating agent of Example 3, it can be seen that SiO ₂ and PbO are added in a ratio of 1: 2 to 1: 2.3. At this time, when the amount of the soft flux is less than the reference range, it is not effective to lower the melting point, and when the amount of the soft flux is more than the reference range, the viscosity is not appropriate for the surface coating.

On the other hand, Table 2 below is made of the structure 40-1 of the lead 40 for refractory residual amount determination according to the present invention, the MgO aggregate and carbon as a main component and the surface of the structure 40-1 in Table 1 After applying the selected coating agent to form a coating layer 50, put in an electric furnace and maintained at 1000 ℃ for 20 hours to compare the weight loss ratio and this shows a result of comparing the erosion index using a rotary erosion machine.

TABLE 2

Inventive Example One 2 3 4 5 MgO aggregate (wt%) 80 to 85 Metal additive (wt%) 4 Binder (resin) (wt%) 3 Carbon (wt%) 6 8 10 12 14 liniment Example 3 Formulation Test result Weight loss ratio 106 100 (standard) 97 98 103 Erosion Index 105 100 (standard) 98 99 104

The erosion index of the refractory 20, which is constructed on the steel bar 10 of the steelworks vessel, is represented by 108. In this case, according to the present invention, the structure 40-1 of the refractory residual amount determination lead 40 is composed of 80 to 85 wt% of MgO aggregate, 4 wt% of a metal additive, and 3 wt% of a binder. The coating layer 50 was formed on the surface of the structure 40-1 by applying a coating agent having the composition of Example 3 shown in Table 1 above. At this time, it can be seen that the erosion index is relatively low in the case of the yeonwa 40 of the invention examples 2 to 4 containing 8 to 12wt% carbon.

According to the present invention, by applying a coating agent for preventing the oxidation of carbon in the MgO aggregate and carbon main edible on the surface of the edible so as to have a lower erosion index than the erosion index of the refractory constructed on the inner surface of the shell. In this case, it is possible to easily determine the remaining amount of refractory remaining in the ladle, thereby contributing to the reduction of labor costs and operational stability.

The foregoing is merely illustrative of the preferred embodiments of the present invention and those skilled in the art to which the present invention pertains recognize that modifications and variations can be made to the present invention without departing from the spirit and gist of the invention as set forth in the appended claims. shall.

Claims (3)

In the refractory remaining amount determination lead installed in the refractory to be able to determine the degree to which the refractory to be constructed to protect the iron bar for the steel mill is melted by the hot melt, A predetermined structure consisting of 80 to 85 wt% MgO aggregate, 8 to 12 wt% carbon, and the remaining binder and metal additive material; It is formed by applying a coating agent containing 20 to 22 wt% of SiO ₂ and 43 to 45 wt% of PbO as a main component and 5 to 7 wt% of Na ₂ O and 7 to 9 wt% of Li ₂ O to the outer surface of the structure. The refractory residual amount edge lead comprised by the coating layer which becomes. The method of claim 1, SiO ₂ and PbO are added to the coating agent in a ratio of 1: 2 to 1: 2.3. The method of claim 1, The MgO aggregate is 85 ~ 90wt% molten molten MgO aggregate, and 10 ~ 15wt% sintered MgO aggregate characterized in that the refractory residual amount determination lead.

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