JPS58151369A - Refractories for blast furnace tap hole launder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refractory for blast furnace tap troughs having a long life.

BACKGROUND ART High alumina refractories containing silicon carbide (5iC) and carbon (C) are known as refractories used in blast furnace tap troughs, particularly for main troughs. This refractory is made of, for example, high-alumina raw materials such as high-purity sintered alumina, fused alumina, or dead burnt materials such as naturally occurring bauxite and pansoil shale. It is made by adding SiC and C to provide corrosion resistance, slag resistance, and hot metal penetration resistance at temperatures of .degree.

In such refractories for blast furnace tap troughs, SiC is
~20 g is added as an effective required amount, especially in the form of a fine powder of less than 100 microns...constituting the matrix of the refractory. In addition, in such refractories for blast furnace tap troughs, as C, crystalline graphite and aromatic hydrogen pitch powder that gives residual carbon strength are added in an effective amount of 1 to 7%. After heating, microscopic carbon deposits form a dense refractory structure.

However, such refractories for blast furnace tap troughs have a problem of short service life, especially when used as the main trough.

The inventors of the present invention conducted research to solve all of the above problems, and as a result, they obtained the following knowledge. That is,
In the above-mentioned blast furnace tap trough refractories, SiC, Ce
The matrix portion containing the slag becomes oxidized and its structure weakens, making it easier for the molten slag to infiltrate there. In addition, the adhesion between the matrix portion and the aggregate is weakened and the support of the aggregate particles is loosened, which causes the refractory to deteriorate in strength and become more susceptible to wear. As a result, fluid abrasion due to hot metal and dissolution/diffusion due to slag occur.
It was found that the refractories were damaged. Therefore, the above
By preventing the oxidation of SiC and C constituting the IJ lux, a blast furnace tap trough refractory with a long life can be obtained.

This invention was made based on the above knowledge, and S
iC, and Ct-containing high alumina refractory raw materials,
The refractory for blast furnace tap troughs is characterized by containing 1 to 5.0% by weight of at least one of B, C, and BN.

The reason for limiting the numerical values as described above in this invention is as follows. That is, B and C have melting points of 2350°C
, BN are stable at high temperatures with a melting point of 3000°C, but when they come into contact with oxygen at temperatures above 1000°C, they decompose and form 520°C.
3 is produced, and this B2O3 reacts with Al2O3,5in2, which is a component of the high alumina refractory raw material, to produce B20
．． - S 102- AJ, 03 series glass is produced and a coating of this glass is formed on the air-contacting surface of the refractory. As a result, air is prevented from penetrating into the refractory structure, thus preventing oxidation of SiC and C within the refractory structure. However, when adding B, C, and C, if the amount added is large, the aroma of the B203-8 i 02-k40s glass formed on the surface of the refractory increases, and the formation of low-melting products. On the other hand, since the amount increases, a large amount of molten metal is melted, and it is more likely to be eroded and lost when it comes into contact with slag. On the other hand, if the amount of B4C,C added is small, the glass coating will be too thin and the SiC inside the refractory structure will
The oxidation of C will not be sufficiently prevented. Therefore, for this reason, the amount of B, C, and C added should be 0.1 to 5.
It was set as 0chi.

〔Example〕

270 parts by weight of sintered alumina (10~1μ = 45 parts by weight,
1μ or less: 20 parts by weight, and 325F = 5 parts by weight particle size structure), SiC of 150 mesh or less: 20 parts by weight,
A refractory of the present invention is produced by adding 150 mesh or less of B, C, BNt-1 in the proportions shown in Table 1 to a material consisting of 2 parts by weight of graphite, 84 parts by weight of pitch, and 5 parts by weight of binder. 1 to 7, comparative refractories 1 and 2, and conventional refractory 1 (which did not contain B, C, or BN) were prepared. .

Each refractory thus obtained was heated at a temperature of 12,000C for 40 hours. As a result, the oxidized layer thickness obtained in the surface layer portion of each refractory is shown in Table 1. Table 1
It is clear from the above that the refractory of the present invention can significantly reduce oxidation of the surface layer of the refractory.

Next, each refractory after the heating was heated at 1550°C for 2
It was subjected to an erosion test for 0 hours and the amount of erosion was measured.

The results are shown in Table 1. From Table 1, it is clear that only the refractories of the present invention exhibited an extremely small amount of erosion loss.

Therefore, from the above, it is clear that the addition of appropriate amounts of B4C and BN sb results in an extremely slow melting speed.

As described above, the present invention can provide a refractory for blast furnace tap troughs that has a long life.

Applicant: Tokyo Ceramics Co., Ltd. Agent: Keitabe Tsutsumi (and 18 others)

Claims (1)

[Claims] High alumina refractory raw material containing SiC and C,
A refractory for a blast furnace tap trough, characterized in that it contains 0.1 to 5.0% by weight of at least one of B4C and BN.