JPS62238316A - Hot repairing method for converter tapping hole - Google Patents

Abstract

PURPOSE:To improve the adhesive property and the shape maintainability as just after repairing work, by constituting a nonaqueous repairing material by combining the specific ratio of powdery resol type phenol resin and granular pitch in a basic refractory material. CONSTITUTION:The nonaqueous hot repairing material for a tapping hole of a converter consists of addition of 2-11pts.wt. of the powdery resol type phenol resin and 6-22pts.wt. of the granular pitch to the 100pts.wt. of the basic refractory material. The using rate of the pitch is preferable to be much than the using rate of the resol phenol resin. Further, the granular pitch needs to be about >=0.2mm grain size. The repairing material having such a composition, is applied to the shape having curved surface, such as the tapping hole of the converter, and the operation is immediately executed after the repairing work.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a repair material for hot repair of a converter tap.

[Conventional technology]

The diameter of the tap hole in the converter gradually increases due to chemical erosion caused by molten steel and molten slag during tapping, and wear and tear caused by the tapping flow. The entrainment of molten slag, etc. occurs, leading to a decline in steel quality.

As a countermeasure to this, we manage the tapping time, and if the tapping time becomes shorter than the specified time, we repair the tapping opening in advance. Such control of the tap hole prevents the aforementioned deterioration in steel quality and ensures the quality of the steel.

The hot repair material for the tap hole of the converter used here is mainly a basic refractory material with tar pitch added, which softens and flows due to the retained heat of the furnace. 1! After IJ, many materials are used that adhere to the repaired surface during the carbonization process and develop strength as a construction body. In addition, as a repair material using resin, there is a non-aqueous repair material using granular phenolic resin disclosed in JP-A No. 58-26080;
A repair material using a granular novolac type phenolic resin, a liquid phenolic resin, and powder pitch disclosed in Japanese Patent No. 0-235772 is used.

[Problem that the invention seeks to solve]

The conventional repair materials described above have the following problems.

(1) In repair materials made by adding tar pitch to basic refractory materials, the amount of tar pitch added is excessive compared to the required amount in order to ensure fluidity during construction and adhesion to the repaired surface. Because of the addition of tar pitch, the repair material has a high porosity, resulting in a construction product with poor durability.At the same time, due to the addition of excessive tar pitch, it takes a long time to carbonize.

(2) In the repair material disclosed in JP-A-58-26080, it is not clear whether the phenolic resin added is a resol type or a novolac type.

When used as a hot repair material for a converter tap, the resol type has poor adhesion between the repaired surface and the repair material.

In addition, in the case of the novolak type, the repair material itself flows due to the heat retained in the furnace, making it impossible to form the repair material into the curved shape of the converter tap, and at the same time requiring a curing time of 20 minutes or more. The converter cannot be operated immediately after the repair material is installed.

(3) Even in the repair material disclosed in JP-A-60-235772, the repair material itself flows due to the heat retained in the furnace.

Even if a repair material that softens and flows as described above is used to repair a converter tap, it can only be applied to a shape with a flat top surface as shown in FIG. For this reason, during tapping, the flow of molten steel is disturbed due to the presence of a part of the lower end corner of the tapping opening, causing the temperature of the molten steel to drop and the molten steel to be exposed to air. It had the disadvantage that the quality of the material deteriorated due to the inclusion of nitrogen and nitrogen.

The present invention solves the above problems, has shape retention properties that allow the construction body to be formed into the shape of the curved surface of the converter tap as shown in Fig. 2, has excellent adhesive properties, and is easy to construct. We conducted various studies on non-aqueous repair materials that can be put into operation immediately.

(Means for solving the problem) As a hot repair material for the tap hole of a converter, 2 to 11 parts by weight of powdered resol type phenolic resin and 6 to 22 parts by weight of granular pitch are used for 100 parts by weight of basic refractory material. The above-mentioned problems were successfully solved by adding 100% of the above-mentioned components, and the present invention was completed.

[Effect]

The resol type phenolic resin and the pitch of the repaired workpiece repaired to the converter tap, which has furnace heat, first soften, and the resol type phenolic resin begins to harden at the same time as it softens, so the workpiece initially has a curved taphole. It can be formed into the following shape and immediately develops the strength to maintain its shape. In addition, pitch becomes a low-viscosity liquid, but since the construction body maintains its shape retention, the repair material as a whole does not soften and flow, and the softened pitch flows within the construction body, which has shape retention, and resol-type phenol Together with the resin, it improves the strength of the construction body itself and the adhesion to the repaired surface.
Improve this. In other words, in the curing process of this repair material, the fast-curing resol-type phenolic resin first imparts shape retention and adhesion to the construction body within a short period of time without affecting the operation of the converter, and then When used in combination with pitch, it develops the adhesion and strength necessary as a repair material.

Basic refractory materials used for hot repair materials include magnesia,
Mainly made of dolomite, etc., with 25% by weight of carbon material
You can also add the following. This carbon material is added when the amount of carbon in the construction body is insufficient due to the amount of residual carbon from the resol type phenol resin and the pitch, taking into consideration the operating conditions.

The purpose of resol type phenolic resin is to develop strength at the initial stage of construction, and for this purpose it is necessary to disperse it uniformly, and powder of 0.1 mm or smaller is used. The amount added is 2 to 11 parts by weight per 100 parts by weight of the basic refractory material, and if it is less than 2 parts by weight, the strength development of the construction body will be delayed.
Moreover, if the amount exceeds 11 parts by weight, the physical properties of the constructed body will deteriorate.

The granular pitch may be any of the five petroleum-based and coal-based pitches.
It is necessary that the particle size is 0.2 mm or more.

The pitch softens and flows in the construction body, which has some degree of shape retention due to the hardening of the resol type phenolic resin due to the furnace heat, and forms a carbon bond with the resol type phenolic resin, but if the pitch is less than 0.2 mm, the particle size is Due to its small size, the flow range is narrow, and in particular, the formation of carbon bonds that maintain adhesion to the repaired surface is poor. The amount added is 6 to 22 parts by weight per 100 parts by weight of the basic refractory material, and if it is less than 6 parts by weight, the amount of flow within the construction will be small and the adhesion to the repaired surface will be reduced. If the amount increases, the physical properties of the constructed body will deteriorate.

Regarding the use of resol type phenolic resin and pitch, it is preferable that there is more pitch than resol type phenolic resin, and the usage ratio is 2:3 to 4:2. This is because the adhesion to the body is poor and early curing cannot be obtained.

As shown above, by obtaining shape retention immediately after construction, it is possible to form the steel into a shape having a curved surface as shown in FIG. 2. By being formed in this way, the flow of the molten steel is not disturbed and flows smoothly, so there is little drop in temperature of the molten steel, and oxygen and nitrogen in the air are not involved, so there is no deterioration in the quality of the steel.

The method for applying the repair material of the present invention is as follows: (1) The repair material is in the form of powder (2) The repair material is placed in a plastic bag, etc. (3) The repair material is molded under low pressure into the desired shape (4) The repair material is shaped into a rod After inserting the refractory and forming it under low pressure into the desired shape, place it on a repair tool (shovel, trowel, etc.) and insert it into the repair surface of the tap hole held roughly horizontally, before the repair material hardens. This is a simple construction method that is compatible with the repair material, and is formed using a repair tool to form a curved surface of the tap hole. .

The term "low-pressure forming" as used herein means forming the product into a shape having a curved surface of the tap hole during construction, and making it possible to carry the molded product. Further, the rod-shaped refractory is a high-pressure molded product of magnesia, magnesia carbon, etc., and its length needs to be at least half the length of the molded product, thereby further improving durability.

〔Example〕

80φ electric furnace with the composition shown in Table 1 maintained at 800℃
Immediately after putting it into a metal frame of 120 h (mm)
Alternatively, the shape retention (return to horizontal state due to flow), baking time, and adhesive strength after 20 minutes of application were all determined. After measuring the adhesive strength, the sample was slowly cooled in carbon, and its physical properties were measured.

As is clear from the results in Table 1, Examples 1 to 4, which used a combination of powdered resol type phenolic resin and granular pitch, had high adhesive strength, short baking time, and excellent shape retention after construction. Comparative example using 0 granular novolak type phenolic resin and granular pitch】- shows a long baking time;
Comparative Example 2, which used granular novolac phenolic resin, liquid novolac phenolic resin, and powder pitch, had a long baking time and poor adhesive strength and shape retention.
Comparative Example 3 using a powdered resol type phenolic resin and granular pitch had a long baking time and was inferior in adhesive strength. This confirms the superiority of the present invention.

20 kg of each of the repair materials of Example 3 and Comparative Examples 1 to 3 were applied to the repaired surface of the tap hole at 600 to 1000°C and formed into the shape of Tap Steel 1'', and the baking time was 3 minutes.

As a result, Example 3 had a charge of 10, and Comparative Example 1.2 had a charge of O.
Charge, Comparative Example 3 was durable for 2 charges.

〔Effect of the invention〕

The hot repair material of the present invention uses a powdered 1-nozole phenolic resin that rapidly hardens as it softens, and a granular pitch that softens and flows, and then carbonizes when heated. It can be formed into a shape with a curved surface, and high adhesiveness can be obtained without softening and flowing as a construction object. In addition, construction was completed in a short time without affecting converter operations, making it possible to start operations immediately.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a converter tap constructed using a conventional repair material, and FIG. 2 is a cross-sectional view of a converter tap constructed using the repair material of the present invention. 1: Repair material 2: Steel tapping brick

Claims (1)

[Claims] A hot repair material for a converter tap, characterized in that 2 to 11 parts by weight of a powdered resol type phenolic resin and 6 to 22 parts by weight of granular pitch are added to 100 parts by weight of a basic refractory material.