Anti-erosion refractory material for calcination of aluminum ash rotary kiln and preparation method of anti-erosion refractory material

Abstract

The invention provides an anti-erosion refractory material for calcination of an aluminum ash rotary kiln and a preparation method of the anti-erosion refractory material, and relates to the technical field of refractory materials. Comprising the following raw materials in percentage by mass: 20%-70% of flint clay with the particle size of 0-5mm, 5%-40% of synthetic mullite with the particle size of 0-5mm, 5%-20% of synthetic mullite powder with the particle size of 0-0.074 mm, 1%-20% of silica powder with the particle size of 0-0.074 mm, 1%-15% of synthetic material powder with the particle size of 0-0.074 mm and 1%-15% of clay with the particle size of 0-0.074 mm. According to the anti-erosion refractory material for calcination of the aluminum ash rotary kiln and the preparation method thereof, a high-viscosity glass phase is generated in situ, and a dynamic protection layer is formed on the surface of the refractory material to prevent permeation of harmful gas, so that the thickness of a metamorphic layer is reduced, damage to a refractory product is slowed down, and the service life is prolonged; through the synergistic effect of the silica powder and the synthetic powder, the refractory material can be sintered at a low temperature, and the production energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of refractory materials, in particular to an anti-erosion refractory material used for calcining aluminum ash in a rotary kiln and a preparation method thereof. Background Art

[0002] During the treatment of secondary aluminum ash in the aluminum ash rotary kiln, refractory materials face multiple challenges such as complex chemical erosion, thermal stress and mechanical wear. There are many components in the aluminum ash that are harmful to refractory materials, such as alkali metal oxides (K2O, Na2O), which come from the alkaline substances remaining in the aluminum ash and the volatile alkali vapor generated during the calcination process. They will react with Al2O3 and SiO2 in the refractory materials to form low-melting-point compounds, resulting in loose material structure and accelerated spalling at high temperatures. Chloride ions (Cl-) and fluoride (F-) come from chlorides (such as AlCl3, NaCl) and fluoride impurities in the aluminum ash. It will react with the oxides in the refractory materials to generate volatile or low-melting-point substances, destroy the density of the material, and aggravate penetration and chemical corrosion; sulfides (SO3, H2S) originate from sulfur-containing compounds in aluminum ash and sulfur oxides generated during the combustion process, which will react with the alkaline components in the refractory materials to generate sulfates, causing volume expansion and structural cracking, aluminum nitride (AlN) and metallic aluminum residues, incompletely recovered metallic aluminum and aluminum nitride impurities in aluminum ash, aluminum nitride decomposes at high temperatures to generate gases such as NH3, resulting in increased porosity inside the refractory materials, molten aluminum penetrates into the refractory materials, and reacts with SiO2 to cause volume shrinkage and spalling.

[0003] Existing refractory materials are often difficult to effectively resist these complex erosions, resulting in increased thickness of the metamorphic layer, shortened service life, increased cost of refractory materials, and also affecting the normal production of aluminum ash rotary kiln. Summary of the Invention

[0004] The present invention aims to provide a corrosion-resistant refractory material for calcining aluminum ash in a rotary kiln and its preparation method. By in-situ generating a high-viscosity glass phase, a dynamic protective layer is formed on the refractory surface to prevent the penetration of harmful gases, thereby reducing the thickness of the metamorphic layer, slowing the damage of the refractory product and thus extending its service life. The synergistic effect of silicon micropowder and synthetic material powder enables the refractory material to complete the sintering process at a lower temperature, reducing production energy consumption and achieving the goal of energy conservation and consumption reduction.

[0005] In order to achieve the above-mentioned thin metamorphic layer thickness and low energy consumption, the present invention provides the following technical solution: a erosion-resistant refractory material for calcining aluminum ash in a rotary kiln, comprising the following raw materials by mass fraction: 20% to 70% of coke slag with a particle size of 0 to 5 mm, 5% to 40% of synthetic mullite with a particle size of 0 to 5 mm, 5% to 20% of synthetic mullite powder with a particle size of 0 to 0.074 mm, 1% to 20% of silicon micropowder with a particle size of 0 to 0.074 mm, 1% to 15% of synthetic material powder with a particle size of 0 to 0.074 mm, and 1% to 15% of clay with a particle size of 0 to 0.074 mm.

[0006] Furthermore, a method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln comprises the following steps:

[0007] Step 1: Raw material pretreatment: Screen the coke stones with a particle size of 0 to 5 mm and the synthetic mullite with a particle size of 0 to 5 mm to remove impurities and oversized or undersized particles; dry the synthetic mullite powder, silica powder, synthetic material powder and clay with a particle size of 0 to 0.074 mm to remove moisture.

[0008] Step 2: Mix the ingredients: Accurately weigh the raw materials according to their mass percentage, put the weighed raw materials into a mixer and mix them thoroughly, add an appropriate amount of water and mix them thoroughly.

[0009] Step 3: Molding: Add the mixed raw materials into the molding equipment to make the refractory product body of the required shape.

[0010] Step 4: Drying: Place the formed green body into a drying kiln for drying.

[0011] Step 5: Sintering: The dried green body is placed in a sintering kiln for sintering, so that the various raw materials in the green body undergo chemical reactions to form a dense refractory material structure.

[0012] Furthermore, in step 2, the amount of water added is 5% to 10% of the total mass of the raw materials.

[0013] Furthermore, in step 2, the mixing time is not less than 30 minutes to ensure that the raw materials are evenly distributed.

[0014] Furthermore, in step three, the molding pressure of the molding equipment is adjusted according to the shape and size of the product, and is generally 10 to 30 MPa.

[0015] Furthermore, in step 4, the drying temperature of the drying kiln is controlled at 100-150°C.

[0016] Furthermore, in step 4, the formed green body is dried in a drying kiln for no less than 24 hours.

[0017] Furthermore, in step five, the sintering temperature of the sintering kiln is controlled at 1300-1450°C.

[0018] Furthermore, in step five, the sintering time is no less than 3 hours.

[0019] Furthermore, in step five, during the sintering process, the heating rate and the holding time need to be controlled.

[0020] The present invention provides a corrosion-resistant refractory material for calcining aluminum ash in a rotary kiln and a preparation method thereof, which has the following beneficial effects:

[0021] (1) In the present invention, a high-viscosity glass phase is generated in situ to form a dynamic protective layer on the surface of the refractory material to prevent the penetration of harmful gases, thereby reducing the thickness of the metamorphic layer, slowing down the damage of the refractory product, and thus improving the service life.

[0022] (2) In the present invention, the synergistic effect of silicon micropowder and synthetic material powder enables the refractory material to complete the sintering process at a lower temperature, thereby reducing production energy consumption and achieving the purpose of energy saving and consumption reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart of a method for calcining corrosion-resistant refractory materials in an aluminum ash rotary kiln and preparing the same. DETAILED DESCRIPTION

[0024] See also Figure 1 The present invention provides a technical solution: a corrosion-resistant refractory material for calcining aluminum ash in a rotary kiln, comprising the following raw materials by mass fraction: 20% to 70% of coke slag with a particle size of 0 to 5 mm, 5% to 40% of synthetic mullite with a particle size of 0 to 5 mm, 5% to 20% of synthetic mullite powder with a particle size of 0 to 0.074 mm, 1% to 20% of silicon micropowder with a particle size of 0 to 0.074 mm, 1% to 15% of synthetic material powder with a particle size of 0 to 0.074 mm, and 1% to 15% of clay with a particle size of 0 to 0.074 mm.

[0025] Specifically, a method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln comprises the following steps:

[0026] Step 1: Raw material pretreatment: Screen the coke stones with a particle size of 0 to 5 mm and the synthetic mullite with a particle size of 0 to 5 mm to remove impurities and oversized or undersized particles; dry the synthetic mullite powder, silica powder, synthetic material powder and clay with a particle size of 0 to 0.074 mm to remove moisture.

[0027] Step 2: Mix the ingredients: Accurately weigh the raw materials according to their mass percentage, put the weighed raw materials into a mixer and mix them thoroughly, add an appropriate amount of water and mix them thoroughly.

[0028] Step 3: Molding: Add the mixed raw materials into the molding equipment to make the refractory product body of the required shape.

[0029] Step 4: Drying: Place the formed green body into a drying kiln for drying.

[0030] Step 5: Sintering: The dried green body is placed in a sintering kiln for sintering, so that the various raw materials in the green body undergo chemical reactions to form a dense refractory material structure.

[0031] Specifically, in step 2, the amount of water added is 5% to 10% of the total mass of the raw materials.

[0032] Specifically, in step 2, the mixing time is not less than 30 minutes to ensure that the raw materials are evenly distributed.

[0033] Specifically, in step three, the molding pressure of the molding equipment is adjusted according to the shape and size of the product, and is generally 10 to 30 MPa.

[0034] Specifically, in step 4, the drying temperature of the drying kiln is controlled at 100-150°C.

[0035] Specifically, in step 4, the formed green body is dried in a drying kiln for no less than 24 hours.

[0036] Specifically, in step five, the sintering temperature of the sintering kiln is controlled at 1300-1450°C.

[0037] Specifically, in step five, the sintering time is no less than 3 hours.

[0038] Specifically, in step five, during the sintering process, the heating rate and the holding time need to be controlled.

[0039] The method of the embodiment was used for detection and analysis, and compared with the prior art, and the following data were obtained:

[0040] Table 1: Detection and analysis table

[0041] Existing technology Example Apparent porosity ≥18％ ≤12％ Metamorphic layer thickness 5-8mm 1-2mm Thermal shock resistance 10-15 times 25-30 times Sintering temperature 1500～1600℃ 1300～1450℃

[0042] According to the data in the above table, it can be concluded that when the embodiment is used, the anti-expansion of the synthetic low-aluminum mullite is achieved, and the synergistic effect of silicon micropowder and synthetic material powder is achieved, so that the energy consumption is reduced by 20-30%, a high-viscosity glass phase is generated in situ at low temperature, the thickness of the metamorphic layer is significantly reduced, and a dynamic protective layer with both compactness and self-repairing ability is formed, achieving the dual goals of resistance to alkali corrosion and energy saving and consumption reduction, improving the service life of the refractory material, slowing down the damage of the refractory material, and thus reducing the use cost of the refractory material.

[0043] The invention provides an anti-corrosion refractory material for calcining an aluminum ash rotary kiln. The refractory material comprises the following raw materials in mass fractions: 20% to 70% of coke slag with a particle size of 0 to 5 mm, 5% to 40% of synthetic mullite with a particle size of 0 to 5 mm, 5% to 20% of synthetic mullite powder with a particle size of 0 to 0.074 mm, 1% to 20% of silicon micropowder with a particle size of 0 to 0.074 mm, 1% to 15% of synthetic material powder with a particle size of 0 to 0.074 mm, and 1% to 15% of clay with a particle size of 0 to 0.074 mm.

[0044] A method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln, comprising the following steps:

[0045] Step 1, raw material pretreatment: screen the coke gemstone with a particle size of 0-5mm and the synthetic mullite with a particle size of 0-5mm to remove impurities and particles that are too large or too small, and dry the synthetic mullite powder, silicon powder, synthetic material powder and clay with a particle size of 0-0.074mm to remove moisture. Step 2, ingredient mixing: accurately weigh each raw material according to the mass percentage of the raw material composition, put the weighed raw materials into the mixer and mix them thoroughly, add an appropriate amount of water and mix them thoroughly. The amount of water added is 5% to 10% of the total mass of the raw materials. The mixing time is not less than 30 minutes to ensure that the raw materials are evenly distributed. Step 3, molding: add the mixed raw materials to the molding equipment to make the refractory product body of the desired shape. The molding pressure of the molding equipment is based on It is adjusted according to the shape and size of the product, generally 10 to 30 MPa. Step 4, drying: the formed green body is placed in a drying kiln for drying. The drying temperature of the drying kiln is controlled at 100 to 150 ° C. The formed green body is dried in the drying kiln for no less than 24 hours. Step 5, sintering: the dried green body is placed in a sintering kiln for sintering, so that the various raw materials in the green body undergo chemical reactions to form a dense refractory material structure. The sintering temperature of the sintering kiln is controlled at 1300 to 1450 ° C. The sintering time is no less than 3 hours. During the sintering process, the heating rate and the holding time need to be controlled. During the sintering process of the silicon powder, the silicon powder reacts with the coke and clay to generate a low eutectic aluminosilicate glass phase, the viscosity of which can reach 10 at 1200 ° C. 5Pa·s or above, synthetic mullite provides the skeleton structure, coke gemstone serves as the matrix, and a continuous glass phase is formed by liquid-phase sintering of silicon micropowder to fill the grain boundary gaps. The synthetic material powder is alumina powder or magnesium oxide powder, which reacts with harmful gases Cl- or F- to form high-melting-point compounds. The compounds combine with the glass to form a dense composite protective layer to inhibit gas penetration. The silicon micropowder forms a liquid phase at 1300-1450℃, which promotes particle rearrangement and densification, reduces the sintering temperature by 150-200℃ compared with the traditional process, shortens the sintering time to 3 hours, and reduces energy consumption by 20-30%.

[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A kind of refractory material for calcining corrosion-resistant refractory materials in aluminum ash rotary kiln, characterized in that: The invention comprises the following raw materials in mass fractions: 20% to 70% of coke gemstone with a particle size of 0 to 5 mm, 5% to 40% of synthetic mullite with a particle size of 0 to 5 mm, 5% to 20% of synthetic mullite powder with a particle size of 0 to 0.074 mm, 1% to 20% of silicon micropowder with a particle size of 0 to 0.074 mm, 1% to 15% of synthetic material powder with a particle size of 0 to 0.074 mm, and 1% to 15% of clay with a particle size of 0 to 0.074 mm.

2. A method for preparing the corrosion-resistant refractory material for calcining aluminum ash in a rotary kiln as claimed in claim 1, characterized in that: The following steps are involved: S1. Raw material pretreatment: Screen the coke stones with a particle size of 0-5 mm and the synthetic mullite with a particle size of 0-5 mm to remove impurities and oversized or undersized particles; dry the synthetic mullite powder, silica powder, synthetic material powder and clay with a particle size of 0-0.074 mm to remove moisture; S2. Mixing ingredients: Accurately weigh each raw material according to its mass percentage, put the weighed raw materials into a mixer and mix them thoroughly, add an appropriate amount of water and mix thoroughly; S3, molding: adding the mixed raw materials into the molding equipment to make the refractory product body of the desired shape; S4, drying: placing the formed green body into a drying kiln for drying; S5. Sintering: The dried green body is placed in a sintering kiln for sintering, so that the various raw materials in the green body undergo chemical reactions to form a dense refractory structure.

3. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 2, characterized in that: In step S2, the amount of water added is 5% to 10% of the total mass of the raw materials.

4. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 3, characterized in that: In step S2, the mixing time is not less than 30 minutes to ensure uniform distribution of the raw materials.

5. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 4, characterized in that: In step S3, the molding pressure of the molding equipment is adjusted according to the shape and size of the product, and is generally 10 to 30 MPa.

6. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 5, characterized in that: In step S4, the drying temperature of the drying kiln is controlled at 100-150°C.

7. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 6, characterized in that: In the step S4, the formed green body is dried in a drying kiln for no less than 24 hours.

8. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 7, characterized in that: In step S5, the sintering temperature of the sintering kiln is controlled at 1300-1450°C.

9. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 8, characterized in that: In the step S5, the sintering time is not less than 3 hours.

10. The method for preparing corrosion-resistant refractory materials for calcining aluminum ash in a rotary kiln according to claim 9, characterized in that: In step S5, during the sintering process, the heating rate and the holding time need to be controlled.

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