JPH0226816A - Preparation of raw material for refractory containing carbon - Google Patents

Abstract

PURPOSE:To prevent carbonaceous material as starting material for refractory contg. carbon from oxidation, and compounded metal from occurrence of hydration reaction thereon by melting a mixture of compounded metal and resin contg. high fixed carbon content and by using a spray-granulation method in the prepn. of raw material for refractory contg. carbon. CONSTITUTION:The raw material for refractory contg. carbon is obtd. by melting the mixture of compounded metal and resin contg. high fixed carbon content and by spray-granulating. The oxidation of carbonaceous material can be more effectively prevented by contg. one or more kinds of compds. contg. boron and SiC in the mixture above-mentioned. When the metal easily subjected to hydration reaction such as Al, Mg is used as compounded metal, the prepn. above-mentioned shows the effect. The method above-mentioned is suitable for application to an amorphous refractory frequently used amorphous carbon such as pitch, as carbonaceous material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to particles used in the production of carbon-containing refractories used, for example, as refractories for lining molten metal containers.

[Conventional technology]

In recent years, as operating conditions have become more severe, carbon-containing materials with excellent corrosion resistance and spalling resistance have been developed as refractories for lining molten metal containers, and these materials have greatly contributed to improved durability.

As a carbon source for such refractories, graphite scales are commonly used in shaped refractories, but in monolithic refractories that use water to provide fluidity, graphite scales can be added by using graphite scales. It is impossible to use a large amount as this will lead to an increase in water content. Therefore, carbon, which has poor oxidation resistance like pitch, can currently only be used in small quantities. From this point of view, prevention of oxidation of carbon added to refractories is an important point in improving the properties of the material.

In order to improve the oxidation resistance and corrosion resistance and hot strength of carbon-containing refractories, it is recommended to add a low melting point metal such as metal aluminum, as described in, for example, JP-A-55-107749.
It is publicly known as described in the publication No.

However, in monolithic refractory materials that use water, such as castable, metal aluminum undergoes a hydration reaction at room temperature, and not only does the effect of metal addition disappear, but also a large amount of hydrogen gas is generated during the hydration reaction. There is a problem in that this causes tissue deterioration.

As a method for suppressing the hydration reaction of the added metal, it was proposed in 1983 that the resin and metal were heated and mixed to coat the metal, imparting hydrophobicity to the metal surface and preventing the hydration reaction.
It is disclosed in Japanese Patent No. 95681 and Japanese Patent No. 58-190876.

However, these measures require a pulverization step in the raw material preparation stage, and it is impossible to completely control the hydration reaction because the metal is exposed on the surface during pulverization.

[Problem to be solved by the invention]

The problems to be solved in the present invention are to prevent the oxidation of the carbon material as a starting material for the carbon-containing refractory material, and to improve the oxidation resistance and corrosion resistance of the carbon-containing refractory material, as well as the metal added to improve the hot strength. The objective is to prevent the occurrence of hydration reactions and to fully exhibit the characteristics of these blended raw materials.

[Means to solve the problem]

The carbon-containing raw material for large-sized products of the present invention is obtained by injection granulation of a mixture of a blended metal and a resin solution with a high fixed carbon content, and the mixture contains a boron-containing compound and one or two types of SiC. By containing more than one type of compound, oxidation of the carbon material can be more effectively prevented.

In the present invention, since the injection granulation method is used as the metal coating means, the metal portion is coated with the resin without being exposed, and the thickness of the coating resin can be arbitrarily changed.

Furthermore, particle size adjustment can be performed only by classification without requiring a pulverization step.

Furthermore, since the surface of the added metal is not exposed and the hydration reaction of the metal can be prevented, it is possible to fully utilize the effect of the compounded metal itself, which is to increase the strength of the refractory in high-temperature ranges. .

The metal used in the present invention is not particularly limited, but metals that easily undergo hydration reactions, such as aluminum or magnesium, are particularly effective. The particle size of the metal applied to the present invention is not particularly limited, but it is 100 to 200 if considering the dispersibility when particles are added to the formulation.
A mesh level is preferable.

The present invention is suitable for application to monolithic refractories that often use amorphous carbon such as pitch as the carbon material.

Comparing the oxidation initiation temperature of amorphous carbon such as pitch and the melting point of a metal such as aluminum, the former is lower. In such cases, it is difficult to prevent oxidation using the metal alone because the metal is insufficiently softened and melted and dispersed.

Boron-containing compounds such as borax, boric acid, and borosilicate glass are known as antioxidants for carbon, which soften and melt at a temperature below the oxidation initiation temperature of carbon to form a glass coating.

However, since this boron base compound itself is a curing retardant for castable refractories, if a large amount is used, it will not be possible to obtain a construction product. was difficult.

According to the present invention, it is possible to prevent elution of materials such as boric acid that dissolve in water and hinder workability.
It is now possible to provide the function as an antioxidant,
It is possible to improve the oxidation resistance of easily oxidizable carbon such as pitch.

As antioxidants, boric acid, borax, borosilicate glass, or compounds such as B and C that form a glass film at a temperature below the oxidation initiation temperature of carbon are effective. It is also possible to use inhibitors.

As the resin used in the present invention, any resin obtained by natural 1 synthesis can be used, but in order to more effectively prevent oxidation, resins with high fixed carbon content such as pitch, phenol resin, and furan resin are preferable. In order to increase the amount of fixed carbon, in addition to resins, we also use scaly graphite, globular graphite, artificial graphite,
It is also possible to use coke, high softening point pitch, etc. in combination.

〔Example〕

Example 1゜ 50 parts by weight of pitch and metal aluminum (99% purity.

50 parts by weight (average particle size: 0.1 mm) were heated, mixed and dissolved, and granulated by an injection granulation method to obtain particles with an average particle size of 0.3 mm.

5% by weight of these particles were added to an alumina pouring refractory material whose particle size had been adjusted, and the mixture was kneaded with 5% by weight of water for 3 minutes.
The hydration stability of resin-coated aluminum metal was investigated by casting it into a metal frame and measuring the exothermic temperature.

The test results are shown in Table 1.

M particle size used for comparative product 1: average particle size 0.1 mm comparative product 1
Manufacturing method of pitch granulation used for: 50 parts by weight of pitch, At! (Average particle size: 0.1 mm, purity: 99%) 50 parts by weight were heated and mixed in a Nigu, then cooled and pulverized. The particle size is an average particle size of 0. The following curing was performed at 35°C, and the apparent porosity was measured at 110°C for 24 hours.

According to the same example, according to the present invention, since the hydration reaction of M does not occur, it is possible to use a relatively large amount of metallic aluminum in an amorphous material that uses water without causing structural deterioration. I understand.

Example 2 A: 50 parts by weight of pitch, 50 parts by weight of aluminum B: 50 parts by weight of pitch, 40 parts by weight of aluminum 11'ls.

Borax 10 parts by weight C: 50 parts by weight of pitch, 30 parts by weight of aluminum.

Particles having an average particle diameter of 0.3 mm and consisting of 10 parts by weight of borax and 10 parts by weight of B and C were obtained by an injection granulation method.

This particulate material was applied to a gutter pouring material of 71220.60%, 5iC 35%, and pitch 5%, and it had oxidation resistance, corrosion resistance,
The hot strength was investigated.

The results are shown in Table 2.

Table 2 The oxidation test consists of 10 samples of 50mm diameter x 100mmH.
00'l: After X3H oxidation and firing, it was cut into two pieces and the thickness of the white layer on the surface was measured.

Erosion index is rotary drum method 1600℃ x 0.5H x 10
Multi-corrosion agent Under the condition of blast furnace slag/pig iron = 8/2, the erosion rate of the regular product (G) is expressed as an index with the value set as 100 (the smaller the number, the better the corrosion resistance).

Hot strength is sample size 40 x 40 x 160
The measurement was carried out under the conditions of 1450°C XIH (in N2 gas flow).

As a result, according to the present invention, it becomes possible to use materials such as borax, which dissolve in water and significantly impede the workability of irregularly shaped materials, so it is impossible to use them in large quantities. It turns out that it is possible to significantly improve the functionality of the material.

Particles according to the present invention /IA', 0360%, SiC
Table 4 shows the results of a practical test where the material was applied to a 35% gutter pouring material and wiped onto the slag zone of a steelworks gutter (trial period: 1 month).

The durability of the material to which the granulation according to the present invention is applied has been improved by 25% compared to the conventional material.

The wear and tear on the shoulders, which are constantly exposed to an oxidizing atmosphere, was very slight, confirming the superiority of the present invention.

Table 3 The present invention was explained using alumina-3iC-carbon material, but the materials include magnesia-carbon material, magnesia-3iC-carbon material, zirconia-SiC-carbon material, alumina-silicon nitride-carbon material. It can be applied to various fixed and amorphous materials including non-oxides such as carbon and SiC.

〔Effect of the invention〕

According to the present invention, since the hydration reaction of M does not occur, it is possible to use water in an amorphous material in a large amount without causing tissue deterioration.

As a result, according to the present invention, it is now possible to use materials such as borax, which dissolve in water and greatly impede the workability of irregularly shaped materials, so it is impossible to use them in large quantities. It turns out that it is possible to significantly improve the functionality of the material.

Claims (2)

[Claims] 1. A method for preparing a raw material for carbon-containing refractories, which comprises melting a mixture of compounded metals and a resin with high fixed carbon content, and spraying and granulating the mixture. 2. One or two of a boron-containing compound and SiC are added to the mixture.
The method for preparing a raw material for carbon-containing refractories according to claim 1, which comprises containing one or more kinds of compounds.