Refractory brick for cement kiln and preparation method thereof

Abstract

The present invention relates to the technical field of refractory materials, and in particular to a refractory brick for cement kiln and a preparation method thereof. The present invention comprises the following components in parts by weight: 55-65 parts of high-iron magnesia sand with a particle size of 5-3 mm; 45-55 parts of high-iron magnesia sand with a particle size of 3-1 mm; 30-40 parts of high-iron magnesia sand with a particle size of ≤1 mm; 35-45 parts of sintered magnesia sand with a particle size of 3-1 mm; 25-30 parts of sintered magnesia sand with a particle size of ≤1 mm; 20-30 parts of fused magnesia-alumina spinel with a particle size of 3-1 mm; 15-20 parts of fused magnesia-alumina spinel with a particle size of ≤1 mm; 12-15 parts of a binder; 8-12 parts of a composite additive; and 3-5 parts of nickel oxide powder. The refractory brick provided by the present invention adopts titanium dioxide and zirconium dioxide composite additives, so that a high melting point phase can be generated in the refractory brick, thereby improving the high temperature stability and corrosion resistance of the refractory brick; in addition, nickel oxide powder is used to produce a synergistic effect with the composite additives, further homogenizing the microstructure, making it have better stability at high temperatures, and extending the service life of the refractory brick.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, in particular to a refractory brick for cement kiln and a preparation method thereof. Background Art

[0002] The cement rotary kiln is divided into three parts: preheating zone, burning zone and cooling zone. The use conditions of the burning zone are the most demanding compared to other working zones of the rotary kiln, and it needs to withstand the most severe thermal, mechanical and chemical damage. Therefore, the performance of the refractory bricks in the burning zone directly affects the safe operation cycle of the rotary kiln system.

[0003] Commonly used refractory bricks in the firing zone include magnesia-chrome bricks, dolomite bricks and magnesia-zirconium bricks. Among them, Cr2O3 in magnesia-chrome bricks is easy to form toxic hexavalent Cr6+ compounds R2CrO4 in the presence of alkali metal oxides and high temperature conditions. If not handled properly, the water-soluble Cr6+ compounds will cause serious water pollution, which strictly restricts the use of magnesia-chrome bricks in cement kilns. The free calcium in dolomite bricks is very easy to hydrate, which also limits the application of dolomite bricks. Magnesia-zirconium bricks have a high expansion coefficient and poor structural toughness. They are prone to cracks and then peeling and damage during application.

[0004] At present, magnesia-alumina spinel bricks are used in cement kiln firing zones to replace the above-mentioned refractory bricks. Magnesia-alumina spinel bricks have good kiln skin performance and service life. However, there are still some problems in the application of magnesia-alumina spinel bricks. For example, under high temperature conditions, low-melting-point mineral phases will be produced inside the magnesia-alumina spinel bricks, making them susceptible to severe chemical erosion and subsequent damage. Summary of the invention

[0005] In order to overcome the defects of the prior art, the technical problem solved by the present invention is to provide a refractory brick for a cement kiln and a preparation method thereof. The present invention adds a composite additive to make a refractory brick, which can form a high melting point phase and improve the high temperature stability and corrosion resistance of the refractory brick.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A refractory brick for a cement kiln, comprising the following components in parts by weight:

[0008]

[0009]

[0010] The high-iron magnesia sand contains MgO≥88%, Fe2O3≤6.0%, and SiO2≤1.0%; the sintered magnesia sand contains MgO≥97%, and SiO2≤0.8%; the fused magnesia-alumina spinel contains MgO≥20.0%, and Al2O3≥75%.

[0011] The binder is one of water glass, sodium tripolyphosphate and sodium hexametaphosphate.

[0012] The particle size of the nickel oxide powder is 200 meshes.

[0013] The composite additive is a composite of titanium dioxide and zirconium dioxide, and the weight ratio of titanium dioxide to zirconium dioxide is 1:4; the particle size of the composite additive is 325 meshes.

[0014] A method for preparing refractory bricks for cement kiln, the specific method steps are:

[0015] 1) Weigh the ingredients according to the above ratio, add high iron magnesia sand, sintered magnesia sand and fused magnesia alumina spinel into a mixer and stir for 5 to 8 minutes;

[0016] 2) Then add the binder, composite additives and nickel oxide powder into the mixer and continue stirring for 8 to 10 minutes;

[0017] 3) Put the evenly mixed raw materials into a hydraulic press to press and shape them into bricks for standby use;

[0018] 4) Place the bricks in a drying kiln and dry at 100℃~150℃ for 15~24h;

[0019] 5) Place the dried bricks in a tunnel kiln and sinter them at 1400-1500°C for 50-65 hours; then take them out and cool them.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The refractory brick provided by the present invention adopts titanium dioxide and zirconium dioxide composite additives, so that a high melting point phase can be generated in the refractory brick, thereby improving the high temperature stability and corrosion resistance of the refractory brick; in addition, nickel oxide powder is used to produce a synergistic effect with the composite additives, further homogenizing the microstructure, making it have better stability at high temperatures, and extending the service life of the refractory brick. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are further described below:

[0023] Example 1

[0024] The present invention provides a refractory brick for a cement kiln, comprising the following components in parts by weight:

[0025]

[0026]

[0027] The high-iron magnesia sand contains MgO≥88%, Fe2O3≤6.0%, and SiO2≤1.0%; the sintered magnesia sand contains MgO≥97%, and SiO2≤0.8%; the fused magnesia-alumina spinel contains MgO≥20.0%, and Al2O3≥75%.

[0028] The binder is one of water glass, sodium tripolyphosphate and sodium hexametaphosphate.

[0029] The particle size of the nickel oxide powder is 200 meshes.

[0030] The composite additive is a composite of titanium dioxide and zirconium dioxide, and the weight ratio of titanium dioxide to zirconium dioxide is 1:4; the particle size of the composite additive is 325 meshes.

[0031] A method for preparing refractory bricks for cement kiln, the specific method steps are:

[0032] 1) Weigh the ingredients according to the above ratio, add high iron magnesia sand, sintered magnesia sand and fused magnesia alumina spinel into a mixer and stir for 5 minutes;

[0033] 2) Then add the binder, composite additives and nickel oxide powder into the mixer and continue stirring for 8 minutes;

[0034] 3) Put the evenly mixed raw materials into a hydraulic press to press and shape them into bricks for standby use;

[0035] 4) Place the bricks in a drying kiln and dry at 100℃~150℃ for 20h;

[0036] 5) Place the dried bricks in a tunnel kiln and sinter them at 1400-1500°C for 55 hours; then take them out and cool them down.

[0037] Example 2

[0038] The present invention provides a refractory brick for a cement kiln, comprising the following components in parts by weight:

[0039]

[0040]

[0041] The high-iron magnesia sand contains MgO≥88%, Fe2O3≤6.0%, and SiO2≤1.0%; the sintered magnesia sand contains MgO≥97%, and SiO2≤0.8%; the fused magnesia-alumina spinel contains MgO≥20.0%, and Al2O3≥75%.

[0042] The binder is one of water glass, sodium tripolyphosphate and sodium hexametaphosphate.

[0043] The particle size of the nickel oxide powder is 200 meshes.

[0044] The composite additive is a composite of titanium dioxide and zirconium dioxide, and the weight ratio of titanium dioxide to zirconium dioxide is 1:4; the particle size of the composite additive is 325 meshes.

[0045] A method for preparing refractory bricks for cement kiln, the specific method steps are:

[0046] 1) Weigh the ingredients according to the above ratio, add high iron magnesia sand, sintered magnesia sand and fused magnesia alumina spinel into a mixer and stir for 7 minutes;

[0047] 2) Then add the binder, composite additives and nickel oxide powder into the mixer and continue stirring for 9 minutes;

[0048] 3) Put the evenly mixed raw materials into a hydraulic press to press and shape them into bricks for standby use;

[0049] 4) Place the bricks in a drying kiln and dry at 100℃~150℃ for 22h;

[0050] 5) Place the dried bricks in a tunnel kiln and sinter them at 1400-1500°C for 58 hours; then take them out and cool them down.

[0051] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. In addition, the various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A refractory brick for cement kiln, characterized in that: Contains the following components in parts by weight:

2. A refractory brick for cement kiln according to claim 1, characterized in that: The high-iron magnesia sand contains MgO≥88%, Fe2O3≤6.0%, and SiO2≤1.0%; the sintered magnesia sand contains MgO≥97%, and SiO2≤0.8%; the fused magnesia-alumina spinel contains MgO≥20.0%, and Al2O3≥75%.

3. A refractory brick for cement kiln according to claim 1, characterized in that: The binder is one of water glass, sodium tripolyphosphate and sodium hexametaphosphate.

4. A refractory brick for cement kiln according to claim 1, characterized in that: The particle size of the nickel oxide powder is 200 meshes.

5. The refractory brick for cement kiln according to claim 1, characterized in that: The composite additive is a composite of titanium dioxide and zirconium dioxide, and the weight ratio of titanium dioxide to zirconium dioxide is 1:4; the particle size of the composite additive is 325 meshes.

6. A method for preparing a refractory brick for a cement kiln according to claim 1, characterized in that: The specific steps are as follows: 1) Weigh the ingredients according to the above ratio, add high iron magnesia sand, sintered magnesia sand and fused magnesia alumina spinel into a mixer and stir for 5 to 8 minutes; 2) Then add the binder, composite additives and nickel oxide powder into the mixer and continue stirring for 8 to 10 minutes; 3) Put the evenly mixed raw materials into a hydraulic press to press and shape them into bricks for standby use; 4) Place the bricks in a drying kiln and dry at 100℃~150℃ for 15~24h; The dried bricks are placed in a tunnel kiln for high temperature firing at 1400-1500°C for 50-65h. Finally, take it out and cool it down.

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