Preparation method of lightweight zirconite spherical refractory aggregate containing high closed pores

Abstract

The invention discloses a preparation method of light-weight zircon spherical refractory aggregate containing high closed pores, which comprises the following steps: putting zircon powder into a charging barrel of granulation equipment, and then adding water accounting for 5-15wt% of the zircon powder into the charging barrel; an aqueous solution accounting for 2-8 wt% of the zirconite powder and containing 0.5-4 wt% of a binder; the rotating speed of the rotor is adjusted to 700-1200 revolutions per minute, and the rotor runs for 5-15 minutes; reducing the rotating speed of the rotor to 100-300 revolutions per minute, operating for 3-10 minutes, taking out the zircon aggregate when all the zircon fine powder forms the zircon aggregate, baking at 100-150 DEG C for 7-15 hours, heating to 1450-1660 DEG C, and keeping the temperature for 2-4 hours to obtain the zircon aggregate. The method can effectively make up for the defect of low erosion resistance of a lightweight refractory material, and can simplify the production process and avoid the crushing process.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory aggregate preparation, and particularly relates to a preparation method of lightweight zirconia spherical refractory aggregate containing high closed pores. Background Art

[0002] In recent years, lightweight refractory materials for working linings of various kilns have become the research focus. Lightweight refractory materials can significantly reduce the heat loss of the working lining, thereby reducing production energy consumption and achieving energy conservation and emission reduction. At the same time, the micro-pores contained in lightweight refractory materials can effectively resist thermal stress and improve the erosion resistance of the working lining refractory materials.

[0003] Currently, lightweighting of refractory aggregates is the main method to achieve lightweight refractory materials. The patent document "A kind of micro-closed pore lightweight corundum refractory aggregate and its preparation method" (CN104177099B) prepared lightweight corundum refractory aggregate containing a large number of micro-closed pores by a wet preparation process. The patent document "A kind of microporous lightweight bauxite refractory aggregate and its preparation method" (CN104177107B) prepared lightweight bauxite refractory aggregate containing closed pores by an organic matter decomposition method. Currently, the main preparation method of lightweight refractory aggregates is the burnout method, and the mechanical method is relatively less used to prepare porous aggregates.

[0004] The common aggregate preparation method is to mix powder with a binder and then form it by a mechanical pressing method, and perform crushing treatment after firing. The preparation process is complex, the production energy consumption is high, and the shape of the crushed aggregates is not uniform. The performance of refractory materials is closely related to the aggregate packing during the preparation process. The aggregate ratio of refractory materials is calculated by the Dinger-Funk equation. The design concept of the Dinger-Funk equation comes from the homogenization and spheroidization of aggregate shapes. When the aggregate particle size shows a gradient change and the aggregate shape shows spheroidization, the density of refractory materials can be effectively improved.

[0005] The patent document "Method for Preparing Zircon Bricks Using Dense Zircon Aggregates" (CN107935608B) introduces a dense zircon brick, which is characterized by using dense zircon aggregates to form zircon bricks through isostatic pressing, but does not involve the preparation methods of lightweight zircon aggregates and spherical aggregates. The patent "Method for Preparing Stratified High-Purity Zircon Refractory Materials" (CN106518107B) introduces a method for preparing a zircon refractory material with a density gradient distribution, which is characterized by a process of stratified isostatic pressing, but does not involve the structural design of lightweight refractory aggregates and the preparation methods of spherical aggregates. The patent document "Manufacturing Process of a Large-Size and Large-Span Zircon Refractory Material" (CN107117963B) introduces a high-density and large-size zircon refractory material, which is characterized by controlling the particle size and particle size distribution during the grinding of zircon powder, but does not involve the preparation methods of lightweight zircon aggregates. Summary of the Invention

[0006] The present invention provides a method for preparing lightweight zircon spherical refractory aggregates with high closed pores. The lightweight zircon spherical refractory aggregates prepared by this method can not only significantly reduce production energy consumption and achieve the purpose of energy conservation and emission reduction, but also effectively compensate for the disadvantage of low erosion resistance of lightweight refractory materials due to their high sphericity, high closed pore rate, and low apparent porosity. At the same time, it can also simplify the production process, eliminate the crushing process, reduce dust emissions, and achieve environmental protection.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A method for preparing lightweight zircon spherical refractory aggregates with high closed pores is as follows: Step 1: First, place zircon powder in the barrel of the granulating equipment, and then add water accounting for 5-15wt% of the zircon powder; an aqueous solution accounting for 2-8wt% of the zircon powder and containing 0.5-4wt% of a binder into the barrel. Step 2: Adjust the rotor speed to 700-1200 revolutions per minute and run for 5-15 minutes. Step 3: Reduce the rotor speed to 100-300 revolutions per minute and run for 3-10 minutes. When all the fine zircon powder forms zircon aggregates, take out the zircon aggregates, bake them at 100-150°C for 7-15 hours, and then heat them up to 1450-1660°C and keep them warm for 2-4 hours to obtain this lightweight zircon spherical refractory aggregate with high closed pores.

[0008] The ZrO2 content of the zircon powder is ≥65wt%, and the SiO2 content is ≤33wt%. The particle size of the zircon powder is ≤0.088mm.

[0009] The binder is one of carboxymethyl cellulose, water glass, and aluminum dihydrogen phosphate.

[0010] The viscosity of the binder is ≥800 MPa·S.

[0011] Among them, the rotor speed is adjusted to 700 - 1200 revolutions per minute and run for 5 - 15 minutes. This is because at high speeds, during the rotation of the powder, agglomeration gradually occurs under the action of the binder. However, due to the high speed, the binding density between the powders is relatively low, and there are some pores between the powders. This part of the pores is in the original state of closed pores. Subsequently, the rotor speed is reduced to 100 - 300 revolutions per minute and run for 3 - 10 minutes. The purpose is: at low speeds, the binding state between the powders is more compact, making the densification degree of the surface of the prepared spherical particles much higher than that of the interior. This enables the surface of the aggregate to densify prior to the interior during the firing process, blocking the outward discharge of some closed pores. Bake at 100 - 150 °C for 7 - 15 hours, then raise the temperature to 1450 - 1660 °C and hold for 2 - 4 hours. The purpose is: after the aggregate is formed, the moisture in the aggregate needs to be baked out to give it a certain strength; the purpose of sintering is to prepare an aggregate with high closed pores and endow the aggregate with strength, facilitating the preparation of the next refractory material. The present invention uses zircon powder as the raw material and directly prepares zircon aggregate by the granulation method. After sintering treatment, zircon aggregate is obtained, and the sphericity of the obtained zircon aggregate is ≥98%; based on the Dinger - Funk packing equation, spherical zircon aggregate is more likely to achieve the closest packing effect.

[0012] Moreover, a relatively high sphericity significantly improves the toughness of the specimen. In the refractory system formed by casting, granular aggregate can effectively improve fluidity. In the refractory system formed by pressing, it can improve the contact area and biting degree between the aggregate and the matrix, thereby enhancing the performance of the specimen.

[0013] In the present invention, under the action of rotational centripetal force in the granulation equipment, water is evenly dispersed and enclosed in the material under the action of the binder; during the sintering process, the binder and water burn out, leaving pores, thereby achieving lightweight. By changing the contact characteristics between the powders at different speeds, a high speed results in a higher central angle, and a low speed results in a lower central angle, thereby changing the pore distribution; thus reducing the central angle of neck sintering between the powders, increasing the sintering driving force, accelerating the grain boundary diffusion rate, accelerating the closure of open pores, increasing the number of closed pores, and at the same time reducing the pore diameter of the closed pores, obtaining a high - strength, high - closed - pore - rate, and good thermal shock resistance zircon refractory aggregate with high closed pores.

[0014] The zirconia refractory aggregate with high closed pores prepared by the present invention has a bulk density of 2.8-3.2 g / cm 3 , an apparent porosity of 10-20%, and a closed porosity of 15-25%.

[0015] Therefore, the present invention has simple industry, low cost and easy industrial production. The prepared zirconia refractory aggregate with high closed pores has high strength, high closed porosity and good thermal shock resistance. Specific embodiments

[0016] The present invention will be further described below in conjunction with specific embodiments, which is not a limitation of its protection scope.

[0017] In this specific embodiment: The ZrO2 content of the zirconia powder is ≥65 wt%, and the SiO2 content is ≤33 wt%; The particle size of the zirconia powder is ≤0.088 mm.

[0018] The viscosity of the binder is ≥800 MPa·S.

[0019] Example 1

[0020] A preparation method of a lightweight zirconia spherical refractory aggregate with high closed pores is as follows: Step 1: First, place the zirconia powder in the barrel of the granulating equipment, and then add 5 wt% of water based on the zirconia powder; an aqueous solution accounting for 8 wt% of the zirconia powder and containing 4 wt% of carboxymethyl cellulose Step 2: Adjust the rotor speed to 700-1200 revolutions per minute and run for 10 minutes. Step 3: Reduce the rotor speed to 100-300 revolutions per minute and run for 3 minutes. When all the zirconia fine powder forms zirconia aggregate, take out the zirconia aggregate, bake it at 150 °C for 15 hours, heat it up to 1450 °C, and keep it warm for 4 hours to obtain this lightweight zirconia spherical refractory aggregate with high closed pores.

[0021] The prepared zirconia refractory aggregate with high closed pores is tested: the bulk density is 2.8-2.9 g / cm 3 , the apparent porosity is 10-14%, and the closed porosity is 19-22%.

[0022] Example 2

[0023] A preparation method of a lightweight zirconia spherical refractory aggregate with high closed pores is as follows: Step 1: First, place the zirconia powder in the barrel of the granulating equipment, and then add 15 wt% of water based on the zirconia powder; an aqueous solution accounting for 2 wt% of the zirconia powder and containing 0.5 wt% of water glass Step 2: Adjust the rotor speed to 700 - 1200 revolutions per minute and run for 15 minutes. Step 3: Reduce the rotor speed to 100 - 300 revolutions per minute and run for 3 minutes. When all the zircon fine powder has formed zircon aggregate, take out the zircon aggregate, bake it at 150 °C for 15 hours, heat it up to 1450 °C, and keep it warm for 2 - 4 hours to obtain this lightweight zircon spherical refractory aggregate with high closed porosity.

[0024] Example 3

[0025] A preparation method of a lightweight zircon spherical refractory aggregate with high closed porosity is as follows: Step 1: First, place the zircon powder in the barrel of the granulating equipment, and then add water accounting for 10 wt% of the zircon powder; an aqueous solution accounting for 7 wt% of the zircon powder and containing 0.5 - 4 wt% of aluminum dihydrogen phosphate into the barrel. Step 2: Adjust the rotor speed to 700 - 1200 revolutions per minute and run for 5 minutes. Step 3: Reduce the rotor speed to 100 - 300 revolutions per minute and run for 8 minutes. When all the zircon fine powder has formed zircon aggregate, take out the zircon aggregate, bake it at 100 °C for 10 hours, heat it up to 1660 °C, and keep it warm for 3 hours to obtain this lightweight zircon spherical refractory aggregate with high closed porosity.

[0026] The zircon refractory aggregate with high closed porosity prepared by the present invention is tested: the bulk density is 3.0 - 3.0 g / cm 3 , the apparent porosity is 10 - 13%, and the closed porosity is 20 - 24%.

[0027] Example 4

[0028] A preparation method of a lightweight zircon spherical refractory aggregate with high closed porosity is as follows: Step 1: First, place the zircon powder in the barrel of the granulating equipment, and then add water accounting for 8 wt% of the zircon powder; an aqueous solution accounting for 5 wt% of the zircon powder and containing 3 wt% of carboxymethyl cellulose into the barrel. Step 2: Adjust the rotor speed to 700 - 1200 revolutions per minute and run for 10 minutes. Step 3: Reduce the rotor speed to 100 - 300 revolutions per minute and run for 5 minutes. When all the zircon fine powder has formed zircon aggregate, take out the zircon aggregate, bake it at 100 - 150 °C for 12 hours, heat it up to 1660 °C, and keep it warm for 3 hours to obtain this lightweight zircon spherical refractory aggregate with high closed porosity.

[0029] The zircon refractory aggregate with high closed porosity prepared by the present invention is tested: the bulk density is 2.9 - 3.1 g / cm 3, the apparent porosity is 16 - 19%, and the closed porosity is 15 - 20%.

[0030] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art: The present invention processes zircon fine powder, water and an aqueous binder solution in a granulating device and fires them under the condition of 1450 - 1660 °C in an air atmosphere. The operation is simple and it can be industrially produced.

[0031] The zircon aggregate prepared by the present invention, as a raw material for refractory materials and structural ceramics, can play the roles of reducing mass, resisting erosion and heat insulation.

[0032] Therefore, the operation of the present invention is simple and it is easy to industrially produce the high-closed-porosity zircon refractory aggregate prepared by this method, which has a high closed porosity, a small bulk density and good spalling resistance.

Claims

1. A preparation method of a lightweight zircon spherical refractory aggregate containing high closed pores, which is characterized in that: Step 1: First, place the zircon powder in the barrel of the granulating equipment, and then add water accounting for 5-15wt% of the zircon powder; an aqueous solution accounting for 2-8wt% of the zircon powder and containing 0.5-4wt% of a binder into the barrel. Step 2: Adjust the rotor speed to 700-1200 revolutions per minute and run for 5-15 minutes. Step 3: Reduce the rotor speed to 100-300 revolutions per minute and run for 3-10 minutes. When all the zircon fine powder has formed zircon aggregates, take out the zircon aggregates, bake them at 100-150°C for 7-15 hours, and then raise the temperature to 1450-1660°C and hold for 2-4 hours to obtain this lightweight zircon spherical refractory aggregate with high closed pores.

2. The preparation method of a lightweight zircon spherical refractory aggregate containing high closed pores according to claim 1, wherein: The ZrO2 content of the zircon powder is ≥65wt%, and the SiO2 content is ≤33wt%.

3. The preparation method of a lightweight zircon spherical refractory aggregate containing high closed pores according to claim 1, characterized in that: The particle size of the zircon powder is ≤0.088mm.

4. The preparation method of a lightweight zircon spherical refractory aggregate containing high closed pores according to claim 1, characterized in that: The binder is one of carboxymethyl cellulose, water glass, and aluminum dihydrogen phosphate; the viscosity of the binder is ≥800MPa·S.