KR100891860B1 - Taphole mix of blast furnace having high corrosion resistivity and superior adhesive property - Google Patents

Abstract

The present invention relates to a refractory used for closing the blast furnace outlet, the object is to provide a refractory for closing the blast furnace outlet excellent in corrosion resistance and adhesion to the material.

Refractory for closing the blast furnace outlet of the present invention for achieving the above object, by weight% silicon carbide: 15-28%, calcined alumina: 3-7%, magnesia: 2-5%, clay: 7-12%, Coke: 7-12%, Silicon-silicon: 2-5%, Silicon nitride: 4-10%, Graphite-coated electrolytic alumina and other unavoidable impurities.

Blast Furnace Outlet, Corrosion Resistance, Adhesiveness, All-Hollow Alumina, Calcined Alumina

Description

Taphole mix of blast furnace having high corrosion resistivity and superior adhesive property}

The present invention relates to a refractory used for closing the blast furnace outlet, and more particularly to a refractory for closing the blast furnace outlet excellent in corrosion resistance and adhesion to the material.

With the emergence of large-scale blast furnaces, the amount of turnout and the number of turnouts are increasing under high temperature and high pressure. Accordingly, as a countermeasure for maintaining blast furnace rust and reducing work loads, a refractory having excellent corrosion resistance (corrosion resistance) and adhesion to materials is required.

Japanese Patent Laid-Open Publication No. 11-29366 discloses 30-50 wt% of alumina raw material, 2-5 wt% of silica raw material, and 15-25 carbon carbide among conventional techniques related to blast furnace closure refractories. To 100% refractory aggregate consisting of 5% by weight, 5-10% by weight of carbonaceous material, 15-30% by weight of nitride, and 5-15% by weight of metal powder, liquid tar of the binder was extrapolated 10-17% by weight. The present invention relates to a mud material for blast-furnace opening modification. This mud material is intended to improve volume stability and densify tissue by improving wear strength against molten iron and slack.

In addition, Japanese Patent Laid-Open No. 11-1374 is a mud material for a tap opening formed by blending refractory aggregate, carbonaceous raw material, refractory clay, and a binder. It is intended to improve early strength and corrosion resistance by containing water.

The prior arts aim at improving corrosion resistance and volume stability of the slag of the refractory for closing the exit opening, but there are problems in corrosion resistance such as deterioration of volume stability at high temperature and expansion of the exit opening due to the end of the exit opening.

In the present invention, the surface of the alumina raw material, which is used as the main raw material in the exit closure refractories, is precisely double coated with pitch and graphite powder to increase corrosion resistance and abrasion resistance, and thus has excellent adhesion to the materials used at the exit port. To provide a refractory for closing the exit opening, the purpose is.

Refractory for closing the blast furnace outlet of the present invention for achieving the above object, by weight% silicon carbide: 15-28%, calcined alumina: 3-7%, magnesia: 2-5%, clay: 7-12%, Coke: 7-12%, Silicon-silicon: 2-5%, Silicon nitride: 4-10%, Graphite-coated electrolytic alumina and other unavoidable impurities.

Hereinafter, the present invention will be described in more detail.

Silicon Carbide: 15 ~ 28% by weight

Silicon carbide in the refractory is an effective material to increase the corrosion resistance to slack and to prevent oxidation of carbon. If the content of silicon carbide is less than 15% by weight, the amount of silicon oxide produced by the oxidation of silicon carbide is less, and the oxidation inhibitory effect is lowered. If the content is more than 28% by weight, the silicon carbide is not self-sintering, so the strength is lowered. It is preferable to limit the content to 15 to 28% by weight.

Calcined Alumina: 3 ~ 7 wt%

Calcined alumina in the refractory is active as an ultra fine raw material, and thus promotes the sintering of the closed refractory material, thereby acting as a dense and firm bonding portion of the refractory. If the content is less than 3% by weight, it does not contribute to the promotion of sintering. If the content is more than 7% by weight, the shrinkage due to oversintering at high temperature is excessive, causing poor porosity. Therefore, the content is limited to 3 to 7% by weight. It is preferable.

Magnesia: 2-5 wt%

Magnesia in the refractory plays a role in controlling the expansion of the exit closure material. If the content is less than 2% by weight does not expand, if the content is more than 5% by weight is severe expansion is unsuitable for use, it is preferable to limit the content to 2 to 5% by weight.

Clay: 7-12 wt%

Clays in refractory materials are used to impart plasticity. If the content is less than 7% by weight, the workability is reduced due to the lack of plasticity, and cracks are generated during filling, which leads to poor porosity due to the penetration of molten iron and slack, and also causes a decrease in depth. In addition, when the content exceeds 12% by weight, it reacts with the slack, so that a large amount of low melt is generated, resulting in enlargement of the starting diameter at the end of the starting line, and therefore, the content is preferably limited to 7 to 12% by weight.

Coke: 7-12 wt%

Coke in the refractory helps to form micropores to help outflow of gas and to increase porosity. If the content is less than 7% by weight, the effect of forming micropores is small, so that the effect of removing volatiles is reduced, and if the content is more than 12% by weight, the formation of micropores is excessive and the strength is lowered. It is preferable.

Metal silicon: 2 to 5 wt%, silicon nitride: 4 to 10 wt%

Metallic silicon and silicon nitride in the refractory promote the sintering at high temperature to increase the high temperature strength, and it is more effective to use the two materials in parallel than to use it alone. When the content of metal silicon and silicon nitride is less than 2% by weight and less than 4% by weight, the effect of promoting sintering is lowered, so that the strength at high temperature is reduced. However, due to oversintering, the structure becomes dense, resulting in poor porosity.

 As the alumina in the refractory, high purity artificial synthetic raw materials such as allothermal alumina, sintered alumina and the like and natural bauxite are used. Of these, the electrolytic alumina is not only effective in corrosion resistance due to coarse crystal grains, but also suitable for coating treatment because the surface of the alumina is rough and has many pores. In the present invention, the graphite powder is coated on the surface of the electrolytic alumina.

 The pre-aluminum alumina coated with graphite powder serves to increase corrosion resistance and adhesion, and is added so that the sum with other components is 100% by weight, most preferably at least 35%.

Graphite coating on the surface of the molten alumina uses a binder, and pitch or carbon black may be used as the binder. Preferably, the pitch is good in terms of workability and carbon content (coal fraction). In the method of coating graphite using pitch as a binder, the surface of the pre-aluminum alumina is heated to 40 to 50 ° C., and then the surface of the alumina is evenly coated with a pitch and then the surface of the sticky alumina is coated. There is a roll mixing milling pressurized using a roll mixer so that the graphite particles are sufficiently thickly coated.

The refractory material of the present invention is used as the exit closure material (mud material). When closing the exit with refractory, it is filled by a mud gun. When using a refractory material as a mud material, tar is mainly used as a binder, and 15 to 17 weight% is normally added by extrapolation. In the present invention, tar is used as a binder according to a conventional method.

Hereinafter, the embodiment of the present invention will be described in more detail.

EXAMPLE

15 weight% tar is extrapolated to the composition of the blast furnace outlet closure refractory having a composition ratio as shown in Table 1, followed by pressure kneading while warming to 60 ° C. After the kneaded material was molded to a size of 40x40x160mm for 12 hours of natural curing, the rate of linear change, bending strength, corrosion resistance, adhesion to spherical materials, and porosity were evaluated, and the results are shown in Table 1 below.

 The rate of change and the bending strength at 300 ° C and 1500 ° C were measured, and the corrosion resistance was maintained at 1550 ° C for 1 hour using blast furnace slag in a high frequency induction furnace to measure the remaining thickness of the specimen. Openness was determined by measuring the depth of excavation at a certain time using a core boring machine. In the adhesion test with a spherical material, half of the metal mold of 40 × 40 × 160 mm size was filled with a specimen fired at 1000 ° C. and the newly kneaded closing refractory was filled to examine the adhesion state of the interface.

As can be seen in Table 1, Inventive Example (1-5), which satisfies the scope of the present invention, has a relatively small linear change rate, a large plastic strength, corrosion resistance and It can be seen that the adhesive strength with the spherical material is excellent and the porosity is good.

As described above, the present invention improves the corrosion resistance and adhesion of the blast furnace closure refractories with the materials, and has useful effects such as extending the departure time and reducing the number of departures.

Claims (1)

By weight, silicon carbide: 15-28%, calcined alumina: 3-7%, magnesia: 2-5%, clay: 7-12%, coke: 7-12%, metal silicon: 2-5%, silicon nitride Iron: 4-10% blast furnace closure refractories with excellent corrosion resistance and adhesion, composed of electrolytic alumina coated with graphite on the remaining surface and other unavoidable impurities.