JPH0688829B2 - Refractory - Google Patents

Description

TECHNICAL FIELD The present invention relates to a refractory brick for iron making having high sintering performance and residual expansivity.

(Prior Art) In the recent steel industry, as the quality, rationalization, and efficiency of products have been improved and new manufacturing methods have been developed, the operating conditions are high temperature, diversification of treatment, and long-term operation. As a condition during use, the temperature rises and the temperature change becomes large, and the operating time becomes long and the slag composition change range becomes wide. Due to such things, the usage conditions for refractories are becoming more and more severe.

In order to meet these conditions, heat resistant spalling resistance Structural spalling resistance due to the penetration of foreign matter such as slag High resistance to chemical erosion resistance, etc. Highly resistant refractory that enables stable operation and long life Is desired.

(Problems to be solved by the invention) Currently, in order to meet this requirement, the raw materials used are being highly purified and upgraded.

In order to take advantage of the characteristics of these carefully selected high-purity raw materials, high pressure molding and firing at high temperature for a long time to increase the degree of bonding between particles and densify the structure Has become an absolute requirement. Especially in the present firing process, it takes about 200 hours (10 days) from kiln-filling to kiln-filling with a magnesia / chromium-based basic refractory, and a high temperature of 1800 ° C or higher is required. . Therefore, a huge amount of fuel (heavy oil) of 600 to 800 is used to burn 1 ton of bricks, resulting in a very high manufacturing cost. The current situation is that this tendency becomes even greater.
Recently, a method for producing these refractory materials by using low temperature treatment (150 ° C to 1000 ° C) using chrome boron alloy powder has been proposed and these problems have been solved, but the drawbacks of this method are As a result, shrinkage occurs at high temperatures during use, mainly the joints (joints) of bricks open, and melting loss progresses from these joints, creating dullness and forming a so-called kamaboko-like shape. However, the characteristics of the material could not be fully utilized because heat reception from multiple faces, melting loss proceeded, cracking, flaking phenomenon occurred, and overall there was a slight improvement compared to the long-time baked product. However, the current situation is that it has not reached the point where it has been sufficiently durable.

(Means for Solving Problems) As a result of various researches conducted by the present inventors in view of such a current situation
Add a chrome-boron alloy of 150 microns or less and Al and / or Al alloy powder to form a dense structure Maintain a residual expansive property Reduce infiltration of foreign substances such as slag Heat spalling resistance We have succeeded in drawing out the results such as increasing the level, and have greatly improved the drawbacks of conventional refractory materials of this kind, and have obtained a refractory material that constitutes a single plate-shaped refractory wall when used.

The product of the present invention contains chromium (Cr) and boron (B) in a molar ratio of 1: 1 to
Chrome boron alloy in the range of 1: 2 and Al and / or A
l Add alloys in the form of fine powder of 0.15 mm or less to make full use of the characteristics of refractory materials carefully selected and 150 ℃ ~ 1
It can be produced by carrying out a curing treatment at a low temperature range of 000 ° C.

That is, the chrome boron alloy powder is very effective for gradually decomposing and oxidizing the active layer during use to enhance the characteristics of the refractory and at the same time enhance the sintering ability to form a dense structure. The Al or Al alloy to form a spinel (MgO · Al ₂ O ₃₎ or mullite _{(3Al 2 O 3 · 2SiO 2} ) gradually between MgO and SiO ₂ in the base material is oxidized during use refractory It imparts residual swelling property to the product. Next, these actions will be described in detail.

(Regarding the effect of addition of chromium boron alloy) By mixing chromium boron alloy powder, it gradually decomposes from the operating layer during use and further oxidizes with Cr and B, respectively, to generate Cr ₂ O ₃ and B ₂ O _3. To do.

The B ₂ O ₃ and Cr ₂ O ₃ generated here work effectively as described later.

B ₂ O ₃ is a typical component of refractory and is hard to sinter, even if it is mixed with MgO, Al ₂ O _3, etc. A dense layer is formed on the working layer of the refractory without damaging the material. This dense layer has high viscosity at high temperature and retains excellent physical properties.

Cr ₂ O ₃ has the effect of significantly improving heat resistance by forming spinel (picromchromite MgO, Cr ₂ O ₃ ) between each of the components MgO, Al ₂ O ₃ and SiO ₂ If it is dissolved in the slag, the melting point will be increased to improve the heat resistance of the slag, and the viscosity of the slag will increase and the chemical reactivity will decrease significantly. Structural percolation is also improved because the permeation of foreign matter into the brick structure is suppressed and the generation of an altered layer due to permeation is reduced.

(Effect of using Al or Al alloy) Al or Al alloy oxidizes during use to become a highly active refractory, and forms spinel or mullite as a reaction with MgO or SiO ₂ in the refractory.

Al → Al ₂ O ₃ + MgO → MgO, Al ₂ O ₃ → Spinel formation → (oxidation reaction) Al → Al ₂ O ₃ + SiO ₂ → 3Al ₂ O ₃ , 2SiO ₂ − Mullite formation →
(Oxidation reaction) Decomposes and oxidizes to form spinel and mullite with the base material, resulting in residual swelling and forming a single-plate fireproof wall, while improving foreign matter penetration resistance and heat resistance and spalling resistance. It is possible to obtain a refractory material which has effects such as the above and which is capable of improving the drawbacks of the conventional similar materials even with the refractory material which is difficult to sinter and making good use of the characteristics of the material used.

The added metal powders gradually decompose and oxidize from the surface layer, so that a uniform sintered layer can be always maintained and a stable state can be maintained.

Reasons for limitation Reasons for setting the chemical composition of boron-chromium alloy to a molar ratio of metallic chromium and boron of 1: 1 to 1: 2 and Cr + B of 90% or more: The content of B (boron) is 1: 1 by molar ratio. In the following cases, the firing effect is low and the improvement in physical quality is small.

When the content of B (boron) is 1: 2 or more in molar ratio When the content of boron is 1: 2 or more in molar ratio, the alloy material is CrB.
₂ + B and contains free B, (boron),
When added to refractory materials, free boron easily migrates in the structure, making it impossible to maintain the target quality and stable and uniform quality. Also, the yield of the material decreases during alloy production and the composition is The variation increases.

The reason why 90% or more of Cr + B is added. The added amount is 0.5% to 10.0%, and when the impurity content increases, there is a drawback that a low melt is formed in the base material. The reason why the powder is less than 0.15 mm Addition of chrome boron alloy The purpose is to improve sinterability and corrosion resistance.

This effect is to improve corrosion resistance and slag penetration resistance, thereby enhancing melting loss and thermal and structural spalling properties. For this purpose, the alloy is decomposed and oxidized to perform their respective functions.

Al or Al, Mg alloy, which is highly active due to oxidation, is Al ₂ O _{3 and} others, which are spinel (MgO-Al ₂ O ₃ ) and mullite (3Al ₂ O ₃ , 2SiO ₂ ).
Therefore, since the residual expansion and the slag permeability are reduced, the reactivity becomes poor and the effect becomes small when the particle size is large. Therefore, it is effective to use a particle size of 0.15 mm or less.

Example Next, an example of the present invention will be described in detail.

1 The chemical component values of the raw materials used in the examples are shown in Table-1.

Using the above raw materials Table-2 Addition amount of metal powder (Cr-B alloy material, Al material) Table-3 Particle size of metal powder (Cr-B alloy material, Al material) Table-4 Chemical difference of metal material (Cr-B alloy material, Al material) (above basic test = result) Table-5 shows each test result for each item of the example (composite addition amount of Cr-B alloy material, Al material).

The manufacturing conditions for the hot specimen are as follows: molding pressure is 1000 kg / cm ² , and curing temperature is 350 ° C.

(Effect of the invention) As shown in the above examples, the conventional magnesia chrome material and the chrome boron alloy additive material of the same material were treated at 1600 ° C.
-1.33% and -1.79%, respectively, but each of the present invention products shows residual expansion properties, and at the same time, the invention examples show the maximum amount of erosion and the penetration depth of foreign substances such as slag. The products are 94% to 100%, 55% to 86%, 54% to 58% and 33% to 52% compared to conventional magnesia-chromium materials.
It is possible to improve significantly in terms of quality. In this way, it is possible to prevent the formation of an altered layer due to the permeation of foreign matter such as slag, and the structural detachment that accompanies this, and most notably, it was possible to retain the residual expansivity as described above. Due to the residual shrinkage of the conventional product, the joints (brick joints) mainly open to form a chamfered shape, resulting in groove-shaped pits and melting damage at the poles, which results in heat reception and erosion from multiple faces. By receiving it, it accelerates melting loss and promotes the phenomenon of stripping of the operating layer, and the characteristics of the material could not be fully utilized and the product had reached the end of its life. Since it can be fully utilized, stable operation can be achieved and the life can be extended, and its effect is great.

Claims (1)

[Claims] 1. A refractory material composed of one or more members
Chromium-boron alloy 0.5% to 10% with an impure component within 10% and Al and / or Al alloy with an impure component within 10% at a molar ratio of chromium to boron of 1: 1 to 1: 2 is 0.5 to 0.5.
% -5.0% added, kneaded and molded using an appropriate organic and / or inorganic binder, and cured at 150 ° C to 1000 ° C, a refractory for iron making.