CN101045635A - Ceramic Al203SiC refractory and preparation method thereof - Google Patents

Abstract

The invention relates to a vitrified Al ₂ O ₃ -SiC refractory brick and a preparation method thereof. The technical scheme is: according to the percentage by weight, 50-80% of high-alumina bauxite clinker, 0-30% of white corundum, 5-30% of brown corundum, 5-25% of industrial silicon carbide, 0% Mix ~20% andalusite, 1~5% ceramic additive, add 1~3% binder and 3~5% water, stir or knead for 10~25 minutes and then press into shape; then in 60~ Dry at 110°C for 12-24 hours or dry naturally indoors for 24-48 hours, and finally burn at 1400-1470°C for 4-8 hours. The vitrified Al ₂ O ₃ -SiC refractory brick prepared by the invention not only has the characteristics of high strength, low porosity, small pore size and good microstructure, but also has the advantages of environmental friendliness, strong resistance to molten iron erosion, and resistance to penetration of high-temperature slag. It has the advantages of good corrosion resistance, oxidation resistance and long service life. It is suitable for the inner lining of metallurgical equipment such as ironmaking blast furnaces, tapping troughs, mixed iron tanks, and mixed iron furnaces.

Description

A ceramic Al2O3-SiC refractory brick and its preparation method

technical field

The invention belongs to the field of refractory materials with high alumina bauxite, white corundum, brown corundum, silicon carbide and andalusite as base materials. In particular, it relates to a vitrified Al ₂ O ₃ -SiC refractory brick and a preparation method thereof.

Background technique

The equipment for smelting, storing and transporting high-temperature molten iron includes ironmaking blast furnaces, tapping troughs, mixed iron tanks (torpedo tanks) and molten iron tanks, mixed iron furnaces and iron furnaces, etc. The lining of these equipment used to be made of clay bricks , High alumina brick masonry. With the application of new metallurgical technologies such as intensified smelting and hot metal pretreatment based on desulfurization, the erosion of the lining brick by molten iron has been intensified, and the use conditions of the lining brick are significantly harsh. This kind of clay bricks and high alumina bricks are not only gradually eroded during use, but more importantly, the destructive effect of slag on the lining bricks is aggravated. →Deterioration of the brick layer causes structural delamination and spalling damage. Therefore, preventing the penetration of slag has become a major problem.

The introduction of graphite and SiC in refractory bricks can effectively prevent the penetration of slag. Therefore, the patented technology of Al ₂ O ₃ -SiC-C bricks (such as JP Hei 1-320265, JP Hei 2-51474, JP Hei 1-528246) was produced and applied accordingly. Although this kind of brick has a good use effect under reducing atmosphere conditions, graphite (C) is easily oxidized under high temperature air conditions. After the graphite (C) is oxidized, the brick body becomes loose and the surface properties of the brick deteriorate, which causes the brick to be ineffective in the middle and late stages. People have taken many measures to prevent graphite oxidation, which not only increases the cost, but also does not solve the fundamental problem.

There are also manufacturers at home and abroad to produce and apply Al ₂ O ₃ -SiC refractory bricks, but the production methods are all made according to the traditional brick production process, the porosity is relatively large, and the permeability and erosion resistance of slag resistance are not good enough. For example " refractory material for torpedo car furnace mouth " (CN98111216.1) although reduced the refractory material consumption of torpedo tank car to a certain extent, did not solve the oxidation problem of graphite (C), and the intensity of brick is also on the low side. Although "aluminum chromium silicon carbide refractory brick" (CN200410032058.0) has good oxidation resistance and strong resistance to iron and slag erosion, it is suitable for use on molten iron tanks, mixed iron truck tanks, and mixed iron furnaces, but the Cr in the brick ₂ O ₃ is volatile at high temperature, which is harmful to human body and environment.

In short, in terms of material selection, high alumina bauxite clinker, white corundum, brown corundum, sub-white corundum, graphite (C), industrial silicon carbide and other materials are commonly used at home and abroad; from the perspective of high temperature resistance, these materials All can meet the requirements for use, but the problem is that the porosity of the refractory bricks prepared according to the above-mentioned brick-making method is relatively large, and it is easy to slag seepage, or the oxidation of graphite (C) causes the quality of the bricks to deteriorate and reduce the performance.

Contents of the invention

The task of the present invention is to provide a high-strength, environmentally friendly, low porosity, small pore size, good microstructure, excellent corrosion resistance and slag penetration resistance, good resistance to high temperature molten iron erosion, and long service life. Al ₂ O ₃ -SiC refractory brick and its preparation method. The refractory brick can be widely used in metallurgical equipment such as the middle and upper parts of ironmaking blast furnaces, tapping troughs, mixed iron furnaces, ladles, mixed iron wagon tanks (torpedo tanks), and melting iron furnaces.

In order to achieve the above tasks, the technical solution adopted in the present invention is: first mix 50-80% high alumina bauxite clinker, 0-30% white corundum, 5-30% brown corundum, 5 ～25% of industrial silicon carbide, 0～20% of andalusite, 1～5% of ceramic additives, plus 1～3% of binder and 3～5% of water, stirring or mixing for 10～25 Minutes later, it is pressed into shape, then dried at 60-110°C for 12-24 hours or indoors for 16-48 hours, and finally fired at 1400-1470°C for 4-8 hours. in:

The particle gradation of the components is: 5-0mm for high alumina bauxite clinker, 1-0mm for white corundum, 3-0mm for brown corundum, 1-0mm for industrial silicon carbide, 1-0mm for andalusite, The ceramization additive is 8-0 μm. The Al ₂ O ₃ content of the high alumina bauxite clinker ≥ 85%, the Al ₂ O ₃ content of andalusite ≥ 52%, the SiC content of industrial silicon carbide ≥ 95%, and the Al ₂ O ₃ content of white corundum ≥ 97%, Al ₂ O ₃ content of brown corundum ≥ 92.5%.

The ceramic additive is a uniform mixture of activated alumina, boehmite and montmorillonite; its weight percentage is 20-50% of activated alumina and 20-50% of boehmite , montmorillonite is 15-40%. The binder is one or more of calcium lignosulfonate, sodium lignosulfonate, sulfurous acid pulp waste liquid, industrial dextrin powder, and polyvinyl alcohol.

Due to the above-mentioned technical scheme, no graphite (C) is added in the mixture, so there is no oxidation problem of the graphite (C). Adding an appropriate amount of industrial silicon carbide can improve the performance of bricks. Because industrial silicon carbide is not only a very high-temperature-resistant material, but also has a low thermal expansion rate, it can prevent the lining brick from being damaged due to excessive internal stress caused by repeated heating and cooling during use. Embrittlement and peeling; in addition, at high temperature, part of SiC oxidizes into gaseous SiO and migrates to the surface of the brick, and then reacts with high-temperature air to oxidize into solid SiO ₂ , which can fill the surface pores of the lining brick and make the surface of the lining brick dense. to prevent the penetration of slag; at the same time, the oxide of SiC and Al ₂ O ₃ on the surface will also form a protective film, which can prevent the infiltration of air, slow down the corrosion of bricks, and prolong the service life.

Therefore, the vitrified Al ₂ O ₃ -SiC refractory brick prepared by the present invention not only has the characteristics of high strength, low porosity, small pore size, and good microstructure, but also has environmental friendliness, strong resistance to molten iron erosion, and high-temperature slag resistance. It has the advantages of good penetration and erosion, anti-oxidation and long service life. Therefore, the Al ₂ O ₃ -SiC refractory brick prepared by the present invention is a high-strength dense refractory lining brick suitable for equipment related to high-temperature molten iron systems, and is widely used in masonry ladles, mixed iron car tanks (torpedo tanks), and mixed iron tanks. Iron furnace, ironmaking blast furnace lining and blast furnace tapping trough, etc.

Detailed ways

Below in conjunction with embodiment, the present invention will be further described:

Example 1 A vitrified Al ₂ O ₃ -SiC refractory brick and its preparation method, the weight percentage of its components is: 55-70% of the high-alumina bauxite clinker with Al ₂ O ₃ content ≥ 85% %, andalusite with Al ₂ O ₃ content ≥ 52% is 5-10%, industrial silicon carbide with SiC content ≥ 95% is 10-17%, and white corundum with Al ₂ O ₃ content ≥ 97% is 3-10% , Brown corundum with Al ₂ O ₃ content ≥ 92.5% is 0-8%, ceramic additive 3-5%, plus 1.0-2.5% binder and 3.5-4.5% water, stirring or mixing for 10-25 minutes Afterwards, press molding; then dry at 60-110°C for 20-24 hours, and then burn at 1430-1450°C for 4-6 hours.

In this example, the particle gradation of each component is: 5-0 mm for high alumina bauxite clinker, 1-0 mm for white corundum, 3-0 mm for brown corundum, 1-0 mm for industrial silicon carbide, and 1-0 mm for andalusite 1 ~ 0mm, the ceramic additive is 8 ~ 0μm.

The ceramic additive in this embodiment is a homogeneous mixture of activated alumina, boehmite and montmorillonite; its percentage by weight is that activated alumina is 30-40%, and boehmite is 30-40%. 40%, montmorillonite is 25-35%; binder is calcium lignosulfonate.

According to the ceramic Al ₂ O ₃ -SiC refractory bricks prepared in Example 1, the measured physical and chemical indicators are: apparent porosity 5.0% (110°C×24h), 5.2% (1450°C×6h); bulk density 2.93g/cm ³ (110°C×24h), 2.92g/cm ³ (1450°C×6h); compressive strength is 256.0MPa (1450°C×6h); tested at 1450°C×3h by static crucible anti-slag method After that, there is basically no penetration and erosion.

Example 2 A vitrified Al ₂ O ₃ -SiC refractory brick and its preparation method, the weight percentage of its components is: 55-75% of the high-alumina bauxite clinker with Al ₂ O ₃ content ≥ 85% %, andalusite with Al ₂ O ₃ content ≥ 52% is 5-10%, industrial silicon carbide with SiC content ≥ 95% is 10-17%, and brown corundum with Al ₂ O ₃ content ≥ 92.5% is 5-10% 3-5% ceramic additives, plus 1.5-2.5% binder and 3.5-5.0% water, stirred or mixed for 10-25 minutes, then pressed into shape, and then dried at 60-110°C for 20-24 hours, Then it is fired at 1430-1450°C for 4-6 hours.

In this embodiment, the particle gradation of each component is: high alumina bauxite clinker is 5-0mm, brown corundum is 3-0mm, industrial silicon carbide is 1-0mm, andalusite is 1-0mm, ceramic additive is 8～0μm.

The ceramic additive of the present embodiment 2 is a homogeneous mixture of activated alumina, boehmite and montmorillonite; its weight percentage is that activated alumina is 30% to 40%, and boehmite is 30% to 40%. 40%, montmorillonite 25-35%; binder is a mixture of sodium lignosulfonate and industrial dextrin powder.

The measured physical and chemical indicators of ceramic Al ₂ O ₃ -SiC refractory bricks prepared according to the method described in this example: apparent porosity 4.9% (110°C×24h), 5.1% (1450°C×6h); bulk density 2.93g/cm ³ (110°C×24h), 2.94g/cm ³ (1450°C×6h); compressive strength is 260.0MPa (1450°C×6h); tested at 1450°C×3h by static crucible anti-slag method After that, there is basically no penetration and erosion.

Example 3 A method for preparing a vitrified Al ₂ O ₃ -SiC refractory brick is that the weight percentage of its components is: 50-65% of the high-alumina bauxite clinker with Al ₂ O ₃ content ≥ 85% %, 10-17% for industrial silicon carbide with SiC content ≥ 95%, 5-15% for white corundum with Al ₂ O ₃ content ≥ 97%, 3-15% for brown corundum with Al ₂ O ₃ content ≥ 92.5% , ceramic additive 3-5%, add 1.5-2.5% binder and 3.5-4.5% water, stir or mix and grind for 10-25 minutes, press to form, and then dry at 60-110°C for 20-20 24h, then fired at 1430~1450℃ for 4~6h.

The particle gradation of each component in this example is: 5-0mm for high alumina bauxite clinker, 1-0mm for white corundum, 3-0mm for brown corundum, 1-0mm for SiC, and 8-0μm for ceramic additives .

The ceramic additive is a homogeneous mixture of activated alumina, boehmite and montmorillonite; its weight percentage is 30-40% of activated alumina, 30-40% of boehmite, montmorillonite Stone is 25 to 35%. The binder is a mixture of sulfurous acid pulp waste liquid and industrial dextrin powder.

According to the ceramic Al ₂ O ₃ -SiC refractory bricks prepared according to this Example 3, the measured physical and chemical indicators: the apparent porosity is 5.1% (110°C×24h), 5.3% (1450°C×6h); the bulk density is 2.93 g/cm ³ (110°C×24h), 2.94g/cm ³ (1450°C×6h); compressive strength is 265.5MPa (1450°C×6h); after 1450°C×3h test by static crucible slag resistance method, Essentially free from penetration and erosion.

Therefore, the vitrified Al ₂ O ₃ -SiC refractory brick prepared in this specific embodiment not only has the characteristics of high strength, low porosity, small pore size, and good microstructure, but also has the characteristics of environmental friendliness, strong resistance to molten iron erosion, and High-temperature slag has the advantages of good penetration and erosion, anti-oxidation, and long service life. It can be widely used in molten iron ladle, mixed iron car tank (torpedo tank), mixed iron furnace, lining of ironmaking blast furnace and blast furnace tapping trough, etc.

Claims (6)

1. A method for preparing ceramic Al ₂ O ₃ -SiC refractory bricks, characterized in that 50-80% of high-alumina bauxite clinker, 0-30% of white corundum, 5 ～30% brown corundum, 5～25% industrial silicon carbide, 0～20% andalusite, 1～5% ceramic additive, plus 1～3% binder and 3～5% water , Stir or knead for 10-25 minutes, press into shape, then dry at 60-110°C for 12-24 hours or dry naturally indoors for 16-48 hours, and finally burn at 1400-1470°C for 4-8 hours. 2. The method for preparing ceramic Al ₂ O ₃ -SiC refractory bricks according to claim 1, characterized in that the particle gradation of the components is: high alumina bauxite clinker 5-0mm, white corundum 1~0mm for brown corundum, 3~0mm for brown corundum, 1~0mm for industrial silicon carbide, 1~0mm for andalusite, and 8~0μm for ceramic additives. 3. The method for preparing ceramic Al ₂ O ₃ -SiC refractory bricks according to claim 1, characterized in that the Al ₂ O ₃ content of the high-alumina bauxite clinker is ≥ 85%, and the Al of andalusite ₂ O ₃ content ≥ 52%, industrial silicon carbide SiC content ≥ 95%, white corundum Al ₂ O ₃ content ≥ 97%, brown corundum Al ₂ O ₃ content ≥ 92.5%. 4. The method for preparing ceramic Al ₂ O ₃ -SiC refractory bricks according to claim 1, characterized in that the ceramic additive is a uniform mixture of activated alumina, boehmite and montmorillonite The percentage by weight is 20-50% of active alumina, 20-50% of boehmite and 15-40% of montmorillonite. 5. The method for preparing vitrified Al ₂ O ₃ -SiC refractory bricks according to claim 1, characterized in that the binder is calcium lignosulfonate, sodium lignosulfonate, sulfurous acid pulp waste liquid , industrial dextrin powder, polyvinyl alcohol in one or more. 6. Ceramic Al ₂ O ₃ -SiC refractory bricks prepared according to the method for preparing ceramic Al ₂ O ₃ -SiC refractory bricks according to any one of claims 1-5.