JPH03257055A - Refractory - Google Patents

Abstract

PURPOSE:To render a dense structure and residual expandability, to reduce wettability with slag and to improve thermal spalling resistance by adding a Cr-B alloy and Al and/or an Al alloy to a refractory material in the form of fine powders. CONSTITUTION:One or more kinds of refractory materials are prepd. and 0.5-10% Cr-B alloy having (1:1)-(1:2) molar ratio of Cr:B and contg. <=10% impuri ties, and 0.5-5.0% Al and/or Al alloy contg. <=10% impurities are added to the refractory materials in the form of fine powders of <=150mum particle size. They are kneaded with a proper org. and/or inorg. binder and the kneaded material is molded and hardened at 150-1,000 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a refractory brick for iron manufacturing that has high sintering performance and residual expansion.

(Conventional technology) In recent years, the steel industry has been promoting higher quality products9, streamlining and increasing efficiency, and new manufacturing methods have been developed. Due to long-term operation, etc., the operating conditions include: (1) high temperatures and large temperature changes, (2) longer operating times, and (2) wider range of slag composition changes. Due to these reasons, the usage conditions for refractories are becoming increasingly strict.

In order to meet these conditions, ■ Heat-resistant spalling characteristics ■ Structural spalling resistance due to the penetration of foreign substances such as slag ■ Fire-resistant properties that are highly resistant to chemical erosion, enable stable operation, and have a long service life. Something is strongly desired.

(Problem that the invention attempts to solve) To address this request currently, ■We are working on increasing the purity and quality of the raw materials we use.

■In order to take advantage of the characteristics of these carefully selected high-purity raw materials, from a quality perspective, it is necessary to mold them under high pressure and sinter them at high temperatures for a long time to increase the degree of bonding between particles and make the structure denser. It has become an absolute requirement for manufacturing. In particular, in the current firing process, magnesia-chromium-based basic refractories require a long time of about 200 hours (10 days) from filling to kiln filling, and require high temperatures of over 1800°C. . Therefore, it takes 600Q to fire 1 ton of bricks.
The manufacturing cost is extremely high, as it uses a huge amount of fuel (heavy oil) of ~80,012 kg. The current situation is that this trend is getting bigger and bigger. Recently, chromium-boron alloy powder has been used for low-temperature treatment (150°C to 1000°C) for these refractory materials.
A manufacturing method has been proposed to solve these problems, but the disadvantage of this method is that it shrinks under high temperatures during use, mainly at the joints of bricks (joints). The joint opens, and the melting loss from this joint progresses, creating a hollow, which becomes a so-called semicylindrical shape.This hollowing determines the lifespan, and heat is received from multiple sides, melting loss progresses, cracks occur, and flaking occurs. In general, there have been some improvements compared to long-fired products, but the current situation is that they have not yet achieved sufficient durability.

(Means for solving the problem) In view of the current situation, the present inventors have conducted various studies and found that by adding powder of chromium boron alloy of 150 microns or less and powder of A9 and/or Al alloy, We succeeded in bringing out results such as forming a structure, maintaining residual expansibility, reducing infiltration of foreign substances such as slag, and increasing heat spalling resistance. It was possible to obtain a refractory material which greatly improves the drawbacks and which can be used to form a plate-like fireproof wall.

The product of the present invention has a molar ratio of chromium (Cr) and boron (B) of 1=
By adding chromium boron alloy and Al and/or Al alloy in the form of fine powder of 0.15 mm or less in a ratio of 1 to 1:2, the characteristics of the carefully selected refractory material can be fully utilized and the It can be produced by performing a curing treatment in a low temperature range.

That is, the chromium boron alloy powder gradually decomposes and oxidizes from the active layer during use, which is very effective in improving the properties of the refractory and at the same time increasing the sintering ability and forming a dense structure. During use, At and Al alloys gradually oxidize and form spinel (MgO) between them and MgO and SiO2 in the base metal.
-At203) and mullite (3Ai203・2SiO□
) to impart residual expandability to the refractory. Next, these effects will be described in detail.

(■ Regarding the effect of adding chromium-boron alloy) By blending chromium-boron alloy powder, it gradually decomposes from the working layer during use, and further oxidizes Cr and B, thereby creating Cr2O3 and B20. and generate.

rB2 B20 generated here. and Cr2O3 each work effectively as described below.

■ B2O3 is a typical component of refractories, and is difficult to sinter between MgO and Al□03, which have a high sintering effect and have little effect on quality properties, so they do not harm material properties. Forms a dense layer in the active layer of refractory material.

This dense layer has high viscosity and excellent physical properties at high temperatures.

■Cr2O3 is spinel (picrochromite MgO) among each component with MgO, Al2O, and 5in2.

The generation of Cr, Oa) has the effect of greatly improving heat resistance, and if it is eluted into slag during steel manufacturing, the melting point will be raised to improve the heat resistance of the slag, and the viscosity of the slag will increase. The reactivity is significantly reduced, which improves corrosion resistance such as reducing the erosion of refractories, and also prevents structural spalling by suppressing the penetration of foreign substances such as slag into the brick structure and reducing the formation of altered layers caused by penetration. Improved.

(■Effects 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 MgO1 or 5in2 in the refractory.

Emperor A → Ai, O, +MgO-+MgO, Al2O, -generation of spinel → (oxidation reaction) Al-+AI, 03+Si○2 →3 A 1203.
Formation of 2SiO2-mullite → (oxidation reaction) It decomposes and oxidizes to produce spinel and mullite with the base material, resulting in residual expansion and forming a fireproof wall of a single plate, as well as foreign matter penetration resistance and heat resistance. It has the effect of improving spalling resistance, and even though it is a difficult-to-sinter refractory material, it has improved the drawbacks of conventional similar materials and has made it possible to obtain a refractory that fully takes advantage of the characteristics of the material used. .

Since the added metal powder gradually decomposes and undergoes an oxidation reaction from the surface layer, a uniform sintered layer can always be maintained and a stable state can be maintained.

Reason for limitation■ Reason for setting the chemical composition value of the 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 in molar ratio : If it is less than 1, the sintering 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 becomes CrB2+B and free B.

When added to refractory materials, free boron easily moves within the structure, making it impossible to maintain bulk quality and stable and uniform quality. As the yield decreases, the variation in components also increases.

The reason why OCr+B was set at 90% or more is that the amount added is 0.5% to 10.0%, and if the impurity components increase, there will be a disadvantage of forming low melting substances against the base material. The purpose of adding chromium boron alloy is to improve sinterability and corrosion resistance.

This effect improves corrosion resistance and slag penetration resistance, thereby increasing erosion loss and thermal and structural spalling properties. For this purpose, the alloy is decomposed and oxidized to perform its respective functions.

At or Al. Mg alloy oxidizes to highly active Al
203 and others This is spinel (MgO-At20.).

Since mullite (3Al20..2SiO,) is formed to reduce residual expansion and slag permeability, if the particle size is large, the reactivity becomes poor and the effect becomes small. For this reason, it is effective to use a particle system with a particle size of 0.15 or less.

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

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

Table 2 Addition amount of metal powder (Cr-B alloy material, Al
(Material) ■Table-3 Particle size of metal powder (Cr-B alloy material.

A plugging material) ■ Table 4 Chemical differences in metal materials (Cr-B alloy material, A plugging material) (Basic tests = results) ■ Table 5 Examples (Combined addition of Cr-B alloy material and At material) The test results for each item are shown below.

The manufacturing conditions for the still-temperature sample were as follows: molding pressure was 1000 kg/af, and curing temperature was 350° C. Details are described in each table of Examples.

(Effects of the Invention) As shown in the above examples, when the conventional magnesia chromium material and the magnesia chromium boron alloy additive material are treated at 1600°C, the comparative crystal phase of 2° 4.5 is -
0,62%, -1,33%.

-1 and 79%, respectively, but all of the products of the present invention show residual expansion properties, and the products of the present invention also show residual expansion properties, as well as the amount of erosion and the penetration depth of foreign substances such as slag, compared to the products fired for the longest time. 94%~100%.

and 55% to 86%, which are 54% to 58% and 33% to 52%, which are great improvements in quality compared to conventional magnesia-chromium materials. In this way, it is possible to prevent the formation of altered layers due to the penetration of foreign substances such as slag, and the accompanying structural peeling, and the most noteworthy thing is that, as mentioned above, it is possible to maintain residual expandability. Because of the residual shrinkage of the conventional product, the joints (brick joints) were mainly opened, resulting in a hollow shape and extremely localized groove-like depressions and erosion. This accelerates erosion and promotes the peeling of the working layer, and the properties of the material cannot be fully utilized and the product has reached the end of its lifespan. When used, it forms a smooth, monolithic working surface, making full use of the properties of the material. By being able to do this, stable operations can be achieved and the lifespan can be extended, and the effects are tremendous.

Claims (1)

[Claims] A refractory material consisting of one or more materials with 0.5% to 10% chromium-boron alloy of 150 microns or less and a molar ratio of chromium and boron of 1:1 to 1:2 and an impurity content of 10% or less.
Add 0.5% to 5.0% of metal powder containing 10% or less of impurities to L and/or Al alloys, knead and mold using an appropriate organic and/or inorganic binder, and heat to 150°C to 100°C.
A refractory for iron manufacturing characterized by being cured at 0°C.