JPH08290960A - Refractory containing carbon - Google Patents

Abstract

PURPOSE: To obtain a refractory containing carbon capable of remarkably improving heat resistant spalling properties of the refractory containing carbon used for the vessels of various molten metals, also improving oxidation resistance and corrosion resistance to prolong the life of the vessels of various molten metals to a large extent. CONSTITUTION: This refractory containing carbon is obtained by adding 0.5-10 pts.wt. one kind or more selected from a single powder, a blended powder or an alloy powder of aluminum, magnesium and silicon and 1-8 pts.wt. heat curing boron modified phenolic resin as a binder to 100 pts.wt. blended material containing 3-30wt.% carbon raw material and the rest of a basic refractory material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-containing refractory used as a lining refractory for various molten metal processing vessels such as a pig iron car, a converter, a molten steel ladle and a vacuum degassing device.

[0002]

2. Description of the Related Art In recent years, with the development of refining technologies such as hot metal pretreatment method, top and bottom blowing method in converter, vacuum degassing method and smelting in ladle, high grade steel has come to be melted, The processing conditions are becoming more and more severe due to the rise in temperature and the extension of residence time. A carbon-containing refractory is used as a refractory lining for such a molten metal container. For example,
In the converter, as described in JP-A-55-115917, it has been proposed to use a magnesia / carbonaceous refractory to which a metal is added in order to prevent carbon oxidation.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The magnesia / carbonaceous refractory proposed in Japanese Patent Laid-Open No. 55-115917 uses a phenol resin as a binder. In this phenol resin, a methylol group and a hydroxyl group, which are functional groups of the benzene ring, undergo a condensation reaction during heating to form a three-dimensional connection structure and develop strength. As a result, when a phenol resin is used as a binder for the carbon-containing refractory, high strength is exhibited, and thus the heat-resistant spalling characteristic of the carbon-containing refractory is reduced.

Further, a metal is added to the carbon-containing refractory material in order to prevent carbon oxidation. Metals are added to oxidize preferentially over carbon.
However, an antioxidant function cannot be expected after the metal is oxidized and converted to an oxide.

In the present invention, the heat-resistant spalling property is excellent,
Another object of the present invention is to provide a carbon-containing refractory that exhibits a permanent antioxidant function.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. Aluminum is added to 100 parts by weight of a mixture consisting of 3 to 30% by weight of carbon raw material and the balance of basic refractory raw material. 0.5 to 10 parts by weight of one or more selected from powders of aluminum, magnesium and silicon alone, mixed powders, alloy powders, and 1 to 8 parts by weight of a thermosetting boron-modified phenol resin as a binder. A refractory material containing carbon.

The carbon raw material used in the present invention is flake graphite,
Any of artificial graphite, electrode scrap, petroleum coke, carbon black and the like can be used, but flake graphite is suitable from the viewpoint of corrosion resistance at high temperatures.

As the basic refractory raw material used in the present invention, electrofused magnesia clinker, sintered magnesia clinker, natural magnesia clinker, dolomite clinker, magnesia / calcia clinker, magnesia / chromia clinker, etc. can be used alone or as a mixture. .

The thermosetting boron-modified phenol resin used in the present invention has a form in which a boric acid group is substituted and bonded at the position of the phenolic hydroxyl group of the phenol resin.
It has the characteristic of being heat-cured without using hexamethylenetetramine, which is a curing agent.For example, a mixture of boric acid and phenol is heated and reacted at about 300 ° C, and then polymerized into resin with paraformaldehyde. It is a thing. The amount of boron contained in the thermosetting boron-modified phenolic resin is not particularly limited, but 0.5 to 1 from the viewpoint of handling and the like.
It is desirable that the amount is 0% by weight, preferably 1 to 6% by weight.

[0010]

The carbon raw material used in the present invention is intended to improve heat spalling resistance and slag penetration resistance.
It is used in the range of 3 to 30% by weight. However, if the amount of the carbon raw material used is less than 3% by weight, the function cannot be sufficiently exerted, and if the amount used exceeds 30% by weight, the corrosion resistance sharply decreases.

The basic refractory raw material used in the present invention is intended to improve the corrosion resistance, and is used within the range of 70 to 97% by weight, which is the residual amount of the carbon raw material. This is because if the amount of the basic refractory raw material used is less than 70% by weight, the corrosion resistance cannot be sufficiently exhibited, and if the amount used exceeds 97% by weight, the heat-resistant spalling property is drastically reduced.

Further, the aluminum, magnesium and silicon single metal powders, mixed metal powders or alloy powders used in the present invention are intended to improve the oxidation resistance, and the total amount of the carbon raw material and the basic refractory raw material is the same. Add 0.5 to 10 parts by weight to 100 parts by weight. However, if the addition amount of these metal powders is less than 0.5 parts by weight, the oxidation resistance cannot be sufficiently exerted, and if the addition amount exceeds 10 parts by weight, the heat-resistant spalling property sharply decreases. Is.

The thermosetting boron-modified phenolic resin used in the present invention is intended to improve the heat-resistant spalling property. The thermosetting boron-modified phenolic resin has a structure having a methylol group and a boric acid group as functional groups of the benzene ring. Therefore, when the thermosetting boron-modified phenolic resin is heated, since the methylol group is present as a functional group that causes a condensation reaction, it is thermally cured without using hexamethylenetetramine as a curing agent. As a result, when the thermosetting boron-modified phenolic resin is used as the binder for the carbon-containing refractory, the strength is developed due to the condensation reaction of the methylol group, but the strength to be expressed is as high as two functional groups that cause the condensation reaction. It becomes smaller than the strength developed when an existing phenol resin is used as a binder, and it is possible to suppress the decrease in heat-resistant spalling property.

Further, when a thermosetting boron-modified phenol resin is added to a carbon-containing refractory in combination with metal powder such as aluminum, a permanent antioxidant function can be imparted. The mechanism is described below. The thermosetting boron-modified phenolic resin and the metal powder added to the carbon-containing refractory form a dense glassy antioxidant film on the surface of the carbon-containing refractory by the following reaction. B (g) + M (g ) → B 2 O 3 + MO → B 2 O 3 in -MO based glass here is that of metal and M, (g) represents the gas phase. Since it becomes possible to form a dense film on the surface of the carbon-containing refractory, it is possible to prevent the diffusion of oxygen into the carbon-containing refractory and to impart a permanent antioxidation function.

The amount of the thermosetting boron-modified phenolic resin added is 1 to 8 parts by weight based on 100 parts by weight of the total amount of the carbon raw material and the basic refractory raw material. This is because if the amount added is less than 1 part by weight, heat spalling resistance and oxidation resistance cannot be sufficiently exhibited, and if the amount added exceeds 8 parts by weight, the corrosion resistance to slag decreases sharply. .

[0016]

Examples of the present invention will be described below. Table 1 shows the test results of Examples, Comparative Examples and conventional products. Each example was kneaded with the compounding composition shown in Table 1, molded by a friction press, heat-treated at 300 ° C. for 24 hours, and then subjected to heat spalling resistance evaluation test, oxidation resistance evaluation test and corrosion resistance evaluation test. I went. Further, the conventional product is disclosed in JP-A-55-115.
It is a magnesia / carbonaceous refractory proposed in Japanese Patent No. 917.

In the heat-resistant spalling property evaluation test, the shape is 50
The operation of immersing a sample of × 50 × 250 mm in hot metal at 1650 ° C for 5 minutes, pulling it up, and then cooling it to room temperature is repeated three times, the elastic modulus before and after the test is measured, and the decrease rate of elastic modulus is calculated. did. The heat-resistant spalling property was expressed as an index, with the elastic modulus reduction rate of the conventional product as 100. The smaller the index, the better the heat-resistant spalling property.

Oxidation resistance evaluation test, the shape is 50 × 50 × 50 mm
The sample was heated in air at a temperature of 1400 ° C. for 10 hours, and the area of the decarburized layer on the cut surface of the sample after heating was measured. For oxidation resistance, the area of the decarburization layer of the conventional product is 100
Is displayed as an index. The smaller the index, the better the oxidation resistance.

The corrosion resistance evaluation test was carried out by the rotary slag test method. The sample shape has a cross section of 50 mm at the top and 115 m at the bottom.
It is a trapezoid with a height of 65 mm and a length of 150 mm. Eight samples of this shape were concentrically attached to each other and subjected to a corrosion resistance evaluation test. After the atmospheric temperature reached 1750 ° C, the test was conducted by adding converter slag of CaO / SiO ₂ = 3.4,
The operation of discharging waste after a lapse of minutes was repeated 6 times. The corrosion resistance was measured by measuring the size of the maximum erosion site of each sample, and indexing it with that of the conventional product as 100. The smaller the index, the better the oxidation resistance.

[0020]

[Table 1]

Examples 1 to 11 of the present invention showed excellent heat spalling resistance and oxidation resistance as compared with the conventional magnesia / carbonaceous refractory material. On the other hand, Comparative Example 12 was inferior in corrosion resistance because the amount of basic refractory raw material added was less than 70% by weight and the amount of carbon raw material was 30% by weight or more. In Comparative Example 13, the basic refractory raw material content was more than 97% by weight and the carbon raw material content was less than 3% by weight. Comparative Example 14 was inferior in oxidation resistance because the amount of the metal powder added was less than 0.5 part by weight. Comparative Example 15
Was poor in heat-resistant spalling resistance because the amount of metal powder added exceeded 15% by weight. Comparative Example 16 was inferior in oxidation resistance and heat spalling resistance because the amount of the thermosetting boron-modified phenolic resin added was less than 1 part by weight. Comparative Example 17 was inferior in corrosion resistance because the addition amount of the thermosetting boron-modified phenol resin exceeded 8% by weight. Comparative Example 18 used hexamethylenetetramine as a curing agent, and was inferior in heat-resistant spalling property because the thermosetting reaction was significantly accelerated.

[0022]

INDUSTRIAL APPLICABILITY The carbon-containing refractory containing the boron-modified phenolic resin of the present invention as a binder has been found to exhibit excellent heat-spalling and oxidizing properties as compared with conventional magnesia / carbonaceous refractories. Therefore, when it is used as a refractory lining for a converter or other refining vessel, it has effects such as extension of furnace life and reduction of refractory cost.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Nonobe 7-1099, Uraibe, Bizen City, Okayama Prefecture (72) Inventor Hiroshi Yasui 32 Takeda, Okayama City, Okayama Prefecture

Claims (1)

[Claims] 1. One kind selected from a single powder, a mixed powder and an alloy powder of aluminum, magnesium and silicon with respect to 100 parts by weight of a mixture comprising 3 to 30% by weight of a carbon raw material and the balance of a basic refractory raw material. Or two or more 0.5-10
A carbon-containing refractory, characterized in that 1 to 8 parts by weight of a thermosetting boron-modified phenol resin is added as a binder.