JPH0450179A - Hot-patching material for snorkel of vacuum deaeration apparatus and patching method using same material - Google Patents

Abstract

PURPOSE:To prevent deterioration into a porous state by inserting a core into a snorkel, putting a patching material composed of a refractory filler, pitch and a specified thermoplastic phenol resin between the inner periphery surface thereof and the core and subsequently further adding a refractory filler thereto. CONSTITUTION:One or more materials selected from dolomite, spinel, zircon, etc., are used as the main material and one or more materials selected from a wetting agent, a dispersant, an antioxidant, limestone, a metal powder, an organic or inorganic fiber, etc., are added there to as necessary to obtain a refractory filler. With 100wt.% above-obtained refractory filler, 5-27wt.% pitch having about 5-0.1mm particle size and 1-10wt.% thermoplastic phenol resin having 40-58 deg.C melting point are blended so that the total quantity of the additives may be 8-30wt.%. A granular patching material is obtained thereby. The interior of a snorkel is then heated and a core is inserted from the lower part thereof after reaching a prescribed temperature. The above-mentioned granular patching material is put in between the inner periphery surface of the snorkel and the core and the above-obtained refractory filler further is added thereto. The patching work is completed without removal of the core after hardening of the patching material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a repair material used for hot repair of a snorkel portion of a vacuum degassing device and a method of using the same.

[Prior Art] Vacuum degassing devices such as DH type and RH type used in molten steel refining are equipped with a snorkel that sucks up or discharges molten steel into a vacuum tank.

The inner peripheral surface of this snorkel suffers from significant erosion due to the flow of molten steel. Therefore, as shown in JP-A-61-117210, for example, a snorkel is hot repaired by inserting a core into the snorkel immediately after use and inserting a repair material between the core and the snorkel. is being carried out.

Conventionally, the water paste repair material used for this repair is
The porosity of the repair tissue increases due to boiling and evaporation of water, and it also has the disadvantage of poor adhesion.

Recently, non-aqueous repair materials using pitch as a binder have been proposed. For example, it can be seen in Japanese Patent Application Laid-Open No. 120419/1983. Since this non-aqueous repair material does not contain added water, it solves all of the above-mentioned problems associated with water-based repair materials. Furthermore, the carbonization of the pitch has the effect that the repair structure becomes a carbon bond with excellent spalling resistance and corrosion resistance.

[Problem to be solved by the invention]

The non-aqueous repair material is fluidized and filled by melting the binder by the heat of the furnace. However, when repairing a snorkel using a core, the part to be repaired is extremely long in the height direction, so the refractory aggregate settles when the repair material flows, causing the upper part of the repair structure to become porous, resulting in a decrease in corrosion resistance. There was the problem of inviting. The upper part of the snorkel is particularly important in terms of the functionality of the vacuum degassing device, and due to the decrease in corrosion resistance in this part, a sufficient repair effect could not be obtained.

Such problems are unique to snorkel repairs. For example, when repairing a horizontal surface such as the bottom of a converter, there is no problem because the repair material spreads due to flow and has a small thickness in the height direction.

An object of the present invention is to provide a nonaqueous repair material that does not cause the above-mentioned problems when repairing a snorkel, and a preferable method for using this repair material.

[Means for Solving the Problems] The repair material of the present invention contains 100 wt% of fire-resistant aggregate, 5 to 27 wt% of pitch and 1 to 10 vt% of thermoplastic phenolic resin having a melting point of 40 to 58°C, The total amount of the pitch and thermoplastic phenolic resin is 8 to 30
This is a hot repair material for the snorkel part of a vacuum degassing device, characterized in that the amount is wt%. Further, the core is inserted into the snorkel from below, and the repair material according to claim 1 is introduced between the inner peripheral surface of the snorkel and the core, and then the refractory aggregate is further introduced thereon. This is an invention of a method for repairing a vacuum degassing furnace snorkel.

The cause of the settling of the refractory aggregate in the repair material is thought to be due to the high fluidity of the repair material as well as the long flow time. The repair material of the present invention is a non-aqueous repair material that uses pitch as a binder, and is blended with a thermoplastic phenolic resin having a specific melting point to give it appropriate fluidity and suppress the settling of fire-resistant aggregate. This solves the problems with conventional materials.

FIG. 1 is a graph showing the melting point of the thermoplastic phenolic resin and the fluidity of the repair material in the repair material having the following composition. Note that this fluidity was measured in the same manner as in the examples described later, and expressed as an index with the fluidity when a thermoplastic phenol resin having a melting point of 48° C. is used as 100.

Magnesia clinker-3~IRIII 5
5wt% 11 meters below 25〃 0.074-also below 20〃 Pitch (melting point 82℃) 3~0.5+am External 15wt% thermoplastic phenolic resin 2~0.5M
External hook 3 Maintaining appropriate viscosity is effective in preventing settling of the refractory aggregate, but it can be seen from the figure that the lower the melting point of the thermoplastic phenolic resin, the greater the fluidity of the repair material.

FIG. 2 is a graph showing the relationship between the amount of thermoplastic phenol resin (melting point: 52° C.) added and the fillability of the repair material in the repair material having the above-mentioned composition.

This filling property was measured in the same manner as in Examples described below. The use of thermoplastic phenolic resin with a low melting point is effective in preventing settling of refractory aggregates, but if the amount added is too large, the flow time becomes too short and the resin hardens without being filled, resulting in poor filling properties, as shown in the same graph. .

The thermoplastic phenolic resin used in the repair material of the present invention is
If the melting point is less than 40°C, there is a concern that the repair material may melt due to the outside temperature during storage or transportation, and cannot be used. If the melting point exceeds 58℃, the flow time of the repair material will be short;
Poor filling properties. Further, if the ratio of the repair material to 100 wt% of the refractory aggregate is less than 1 wt%, the fluidity of the repair material is low, so that the effect of suppressing the settling of the refractory aggregate cannot be obtained. 10wt
%, the fluidity of the repair material becomes too low, resulting in poor filling properties.

Pitch has a large amount of fixed carbon and has the effect of forming a strong carbon connective tissue in the repair material. If it is less than 5 wt%, the amount of fixed carbon in the binder as a whole will be small, and the corrosion resistance of the repair material will be poor. 2
If it exceeds 7 wt%, the flow characteristics of the repair material will increase, and the effect of suppressing sedimentation of the refractory aggregate will be impaired. The melting point is not particularly limited, and for example, the melting point is 50 to 130°C.
can be used.

The above thermoplastic phenolic resin and pitch have a content of 8~
30%it%. If it is less than 8 wt%, it has no effect as a binder. If it exceeds 30 wt%, the porosity of the repaired structure will increase, resulting in poor corrosion resistance. Moreover, the particle size of the thermoplastic phenol resin and pitch is preferably 5 to 0.1 mm.

The type of refractory aggregate is not particularly limited, and examples include magnesia, dolomite, lime, spinel, chromite, alumina, silica, alumina-silica, zircon, zirconia, silicon carbide, or bricks made of these as aggregates. The main material is one or more selected from scraps. If necessary, one or more selected from wetting agents, dispersants, antioxidants, carbon, limestone, slaked lime, metal powder, organic fibers, metallic fibers, inorganic fibers, etc. may be added.

When applying repair materials using pitch as a binder, the repair material is introduced while the smoke emitted from the pitch is sucked out using a smoke evacuation device to preserve the working environment. For this reason, light particles of refractory aggregate are sucked into the smoke evacuation system,
The particle size structure of the refractory aggregate may become unbalanced.

Therefore, the repair material of the present invention may be granulated to eliminate apparent fine particles and prevent suction of fine particles during construction. In this granulation, for example, an appropriate amount of a non-aqueous binder is added to the entire blend, and after pressure molding, the mixture is crushed to a particle size free of fine particles. Alternatively, an appropriate amount of a non-aqueous binder may be added to the entire blend and granulated by a transfer method or the like.

After the granulated repair material is placed between the core and the snorkel, the granulated state is loosened by melting of the binder, and the repair material is filled. The non-aqueous binder used for this granulation is not limited to pitch and phenol resin, but may also include furan resin, phenol resin, epoxy resin, paraffin, and the like.

To repair a snorkel, a repair material is put between the snorkel and the core.1 After the repair material of the present invention is put in as described above, if fire-resistant aggregate is added on top of it, the repair structure of the upper part of the snorkel is It is more effective in preventing porous formation.

After the repair material is fluidized, its viscosity gradually increases due to the evaporation of the volatile components of the binder. For this reason, the sedimentation of the refractory aggregate added later is suppressed, and a repair structure in which the refractory aggregate is more or less evenly distributed vertically is obtained.

After the repair material is put in as described above and the repair material is completely cured, the repair is completed without removing the core. When the vacuum degassing equipment operates, the core melts away when it comes into contact with molten steel.

〔Example〕

Examples of the present invention and comparative examples thereof are shown below.

Table 1 shows the quality values of the phenolic resin and pitch used on each side. Table 2 shows the formulation composition and test results for each side.

B in Table 1 is within the range defined by the present invention, and C is conventionally used.

The test method is as follows.

Viscosity: - Repair material 80 formed into a square with sides of 70 mm
0g was placed in an electric furnace at 700°C and heated, the dimension of the base expanded by fluidization was determined, and the result was expressed as an index with the result of Comparative Example 1 set as 100. The higher the number, the lower the viscosity.

Lined with basic refractory, inner diameter 400mm, height 100mm
The inside of a 0mm simulated snorkel is heated with a gas burner, and when the temperature of the inner peripheral surface reaches 1000℃, the outer diameter is 300℃.
A metal core of mm was charged, and a repair material was placed between the simulated snorkel and the core. Flow time, fillability, and corrosion resistance were measured on the repaired simulated snorkel. Durability was tested using an actual machine in which the snorkel of a DH vacuum degasser was repaired.

Flow time: The time from when the repair material became fluid until it hardened was measured.

Fillability: Samples were cut from above and below the repaired tissue of the simulated snorkel, and the edible porosity of each was measured.

A specimen was cut from the repaired structure at approximately the center of the height of the simulated snorkel, and the erosion dimension was measured by a rotational erosion test. The numerical value was expressed as an index with the erosion damage dimension of Comparative Example 1 set as 100. The smaller the value, the better the corrosion resistance.

Performance: The number of durable charges of the snorkel was determined with and without additional refractory aggregate added.

In addition, 100 kg of magnesia clinker with a particle size of 5 m111 or less was added as a fire resistant aggregate.

According to the results in Table 2, Examples 1 to 9 all have short flow times and exhibit appropriate flow characteristics, so they are excellent in filling properties. There is little difference in fillability in the vertical direction, and as a result, it has excellent corrosion resistance and durability.

On the other hand, in Comparative Example 1, the binder was only pitch, and the filling properties in the upper part were low due to settling of the refractory aggregate.In Comparative Example 2, the proportion of thermoplastic phenolic resin was high, and the flow time was too short, resulting in an overall The filling properties are poor.

Comparative Example 3 has a large proportion of binder and a small proportion of refractory aggregate, resulting in poor filling properties. Comparative Example 4 uses a thermoplastic phenolic resin whose melting point is higher than that defined in the present invention, and has high viscosity and poor filling properties. Comparative example 5
Since the proportion of binder is small and sufficient fluidity cannot be obtained, the filling property is poor.

In addition, the durability of the products to which refractory aggregate was added was improved compared to those without the addition of fire-resistant aggregate. When we dismantled and observed the structure of the repair material after repair, we found that in the case where refractory aggregate was added, the refractory aggregate was less unevenly distributed in the lower part, and the refractory aggregate was almost evenly distributed in the vertical direction. It was confirmed that there is.

〔Effect of the invention〕

The repair material of the present invention contains pitch and a thermoplastic phenolic resin with a low melting point as a binder in a specific ratio, so that excellent filling properties can be obtained in hot repair of the snorkel part using a core. It is possible to prevent bolus distortion of the repair material structure, which is seen with conventional materials. In addition, in the repair method using this repair material, if fire-resistant aggregate is added,
The effect of preventing the structure of the repair material from becoming porous becomes even more remarkable.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the melting point of a thermoplastic phenolic resin and the fluidity of a repair material. FIG. 2 is a graph showing the relationship between the amount of thermoplastic phenol resin added and the fillability of the repair material. Figure 1 Thermoplastic phenolic resin □ suspended by heat ('b) 11 people Knoll 41' and Kazu's name 5 go (ri [Irinsu, tzu) procedure manual January 17, 1991 Day

Claims (2)

[Claims] (1) Pitch 5-27 for 100wt% of fire-resistant aggregate
A thermoplastic phenolic resin for a snorkel part of a vacuum degassing device, which contains 1 to 10 wt% of a thermoplastic phenolic resin with a melting point of 40 to 58°C, and a total amount of the pitch and thermoplastic phenolic resin of 8 to 30 wt%. Interval repair material. (2) Insert the core into the snorkel from below, add the repair material according to claim 1 between the inner peripheral surface of the snorkel and the core, and then add fire-resistant aggregate on top of it. , How to repair a vacuum degassing furnace snorkel.