JP3662094B2 - Alumina-plug for carbonaceous gas injection - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bottom-blown plug having a through hole to be attached to a molten metal refining furnace such as a metal melting reduction furnace.
[0002]
[Prior art]
In general, a metal smelting reduction furnace uses an alumina-carbon refractory gas blowing plug, but there is a large melting loss around the through-hole pipe for gas blowing, and improvement in strength and corrosion resistance are desired.
[0003]
[Problems to be solved by the invention]
However, since a stainless steel pipe used as a through hole for injecting gas is very easy to melt and deteriorate with respect to heat, the gas blowing plug is melted around the stainless steel pipe. During use, the inside of the stainless steel pipe is cooled because gas flows, but the outside of the stainless steel pipe becomes hot because it is in contact with the alumina-carbon refractory having high thermal conductivity. Therefore, the outer periphery of the stainless steel pipe is always exposed to a reducing atmosphere at a high temperature, and the stainless steel pipe deteriorates. The deterioration is caused by the combination of Cr contained in the stainless steel pipe with carbon of the alumina-carbon refractory. The production of chromium carbide such as CrC ₂ is more advanced, and this deterioration of the stainless steel pipe is one cause of shortening the service life of the gas blowing plug.
[0004]
[Means for Solving the Problems]
The present invention relates to an alumina in which a gas blowing through-hole pipe having an MgO-based coating layer in which an outer periphery of through-holes of a plurality of stainless steel pipes is coated with an MgO-based coating material in a refractory containing carbon and graphite is provided. - in plug included carbonaceous gas blown, MgO electrolyte coating layer, the MgO ultrafine 10-99 wt% as a main _{component, SiO 2, Al 2 O 3} , ZrO 2, metallic aluminum or Al-Mg alloy metal An alumina-carbonaceous gas blowing plug characterized by adding 0.1 to 50% by weight of fine powder and containing no carbon.
[0005]
By forming the MgO coating layer 2 on the outside of the stainless steel pipe, avoiding the direct contact of the stainless steel pipe 1 with the alumina-carbonaceous material 3, the carbon in the alumina-carbonaceous material 3 and the Cr contained in the stainless steel pipe Is to prevent the deterioration of the stainless steel pipe. Further, the MgO coating material is composed of 10 to 99% by weight of MgO ultrafine powder as a main component, and reacts with alumina contained in the alumina-carbon refractory 3 to generate spinel. Abrasion is improved and the service life of the gas blowing plug is improved.
[0006]
If the MgO coating material is less than 10% by weight of MgO ultrafine powder, it is one of the effects of the present invention, and spinel cannot be generated by reacting with alumina in the alumina-carbonaceous refractory. It is an appropriate range.
The addition of 0.1 to 50% by weight of fine metal powder of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , metal aluminum or Al—Mg alloy is to improve the sintering of the MgO-based coating layer.
[0007]
【Example】
An aqueous solution of MgO coating material containing 90% by weight of MgO ultrafine powder and 10% by weight of SiO ₂ is prepared on the outer periphery of a stainless pipe 1 having an inner diameter of Φ1.0 mm and an outer diameter of Φ3.0 mm as a through hole. The coating was applied to a thickness of 0.1 mm. A stainless steel pipe having this MgO-based coating layer 2 is used as a gas-injection through-hole pipe 1 and is formed in an alumina-carbon refractory 3 to form a metal smelting reduction furnace shown in FIGS. A gas injection plug was manufactured and an actual furnace experiment was conducted.
[0008]
【The invention's effect】
The alumina-carbonaceous gas blowing plug according to the present invention is provided with a MgO-based coating layer on the outer periphery of the through-hole stainless steel pipe, thereby improving the strength by spinel formation and chromium carbide by the reaction between the stainless steel pipe and the alumina-carbonaceous refractory. It was found that by suppressing the production of stainless steel and preventing the deterioration of the stainless steel pipe, the actual furnace durability index was 320 compared to 160 of the conventional product, which was twice as great.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a gas blowing plug according to the present invention.
FIG. 2 is a cross-sectional view taken along line AA of the gas blowing plug of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Through-hole stainless steel pipe 2 MgO quality coating layer 3 Alumina-carbon quality refractory 4 Gas introduction pipe 5 Gas pool

Claims (1)

Alumina-carbonaceous gas with a gas-injecting through-hole pipe having an MgO-type coating layer coated with an MgO-type coating material on the outer periphery of the through-holes of a plurality of stainless steel pipes in a refractory containing carbon and graphite in blow plug, MgO electrolyte coating layer, the MgO ultrafine 10-99 wt% as a main _{component, SiO 2, Al 2 O 3} , ZrO 2, metallic aluminum or Al-Mg alloy fine metal powder 0.1 A plug for injecting alumina-carbonaceous gas, which is characterized by adding ˜50% by weight and containing no carbon.

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