CN109369202B - Method for preparing high-quality calcium hexaluminate refractory raw material by two-step roasting method - Google Patents
Method for preparing high-quality calcium hexaluminate refractory raw material by two-step roasting method Download PDFInfo
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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Abstract
The invention belongs to the field of refractory materials, and particularly relates to a method for preparing a high-quality calcium hexaluminate refractory raw material by using a two-step roasting method. Adopts industrially produced alpha-Al2O3The method for preparing calcium hexaluminate by using high-quality limestone as a calcium source as an aluminum raw material in all processes comprises the following steps: (1) crushing and mixing; (2) primary calcination; (3) pressing into blocks for molding; (4) and (5) calcining and forming. By utilizing the method, high-quality calcium hexaluminate refractory raw materials with high purity can be produced through a short process flow and low energy consumption.
Description
Technical Field
The invention belongs to the field of refractory materials, and particularly relates to a method for preparing a high-quality calcium hexaluminate refractory raw material by using a two-step roasting method.
Background
The high-temperature resistant light refractory material is always the key development field in the field of refractory materials. The calcium hexaluminate not only has the characteristics of high melting point and light weight, but also has the advantages of relatively stable chemical properties, good heat resistance and thermal expansibility and the like. The sheet structure of the material also enables the material to have a larger surface area, so that the heat radiation loss of reactants to the environment can be effectively reduced under a high-temperature condition, the weight of the material can be obviously reduced, and the corrosion resistance of the material to slag and metal melts is relatively better due to the high alumina content of the material. At present, the related calcium hexaluminate materials are widely applied to various fields such as refractory materials of metallurgical furnaces, high-temperature erosion resistant materials of chemical engineering, heat insulation layers in the aerospace process and the like.
However, in the preparation process of calcium hexaluminate, the volume expansion process of crystal transformation occurs in the synthesis process of calcium hexaluminate at high temperature, so that the performance of the sintered material is relatively poor. In order to improve the synthesis amount of the calcium hexaluminate and improve the self-performance of the material, the material is generally calcined at a high temperature of 1700-1800 ℃ for multiple times or some additives are added to obtain a relatively good calcium hexaluminate product. However, these methods not only bring about a great deal of energy waste, but also reduce the use limit temperature and erosion resistance of the refractory material due to the introduction of the additive.
Therefore, in order to solve the above problems, it is necessary to develop a new method for producing a high-quality calcium hexaluminate refractory raw material with high purity with low energy consumption.
Disclosure of Invention
The invention aims to provide a method for preparing a high-quality calcium hexaluminate refractory raw material by using a two-step roasting method, and the high-quality calcium hexaluminate refractory raw material with higher purity can be produced by using the method through a shorter process flow and lower energy consumption.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for preparing high-quality calcium hexaluminate refractory material by two-step roasting method using industrial alpha-Al2O3The method for preparing calcium hexaluminate by using high-quality limestone as a calcium source as an aluminum raw material in all processes comprises the following steps: (1) crushing and mixing; (2) primary calcination; (3) pressing into blocks for molding; (4) and (5) calcining and forming.
The method for preparing the high-quality calcium hexaluminate refractory raw material by using the two-step roasting method comprises the following steps of: limestone powder and industrial alpha-Al2O3The particle size of the powder is controlled below 100 meshes, and the limestone powder and industrial alpha-Al are mixed2O3Mixing the powder according to the mass percent of 14% and 86% respectively.
The method for preparing the high-quality calcium hexaluminate refractory raw material by using the two-step roasting method comprises the following steps of: and (3) feeding the mixed powder into a high-temperature kiln, roasting at 1500-1600 ℃ for 25-35 min, and cooling to form a semi-finished product calcium hexaluminate powder.
The method for preparing the high-quality calcium hexaluminate refractory raw material by using the two-step roasting method comprises the following steps of: and (3) according to the shape design after firing, pressing and forming the semi-finished calcium hexaluminate powder prepared in the step (2) by a press machine.
In the method for preparing the high-quality calcium hexaluminate refractory raw material by using the two-step roasting method, the forming pressure is adjusted according to the surface areas of different materials: when the maximum diameter of the molding surface is less than 2 cm, the pressing force of 80-100 MPa is adopted; when the maximum diameter of the molding surface is more than 2 cm and less than 5 cm, the pressing force of more than 100MPa and less than 200MPa is adopted; and so on.
The method for preparing the high-quality calcium hexaluminate refractory raw material by using the two-step roasting method comprises the following steps of: and (4) delivering the product prepared in the step (3) into a high-temperature kiln, roasting at 1500-1600 ℃ for 50-70 min, and cooling to obtain the high-quality calcium hexaluminate refractory raw material.
The method for preparing the high-quality calcium hexaluminate refractory raw material by using the two-step roasting method comprises the following technical parameters: the apparent porosity is controlled below 50%, and the volume density is 1.70g/cm3The compressive strength is 21.00MPa or more.
The design idea of the invention is as follows:
the light refractory material with high purity is the development direction of the refractory material industry which needs to solve the problem urgently and is suitable for large-scale industrial production. From the practical production and application perspective, the invention firstly adopts relatively high-quality raw materials to ensure the purification of the production process and reduce the additional energy and economic waste required by removing impurity components in the production process. Secondly, a two-step calcination method is adopted to prevent and eliminate volume expansion and internal structure fracture caused by aluminate crystal form transformation in the process of one-step synthesis or multi-step gradient synthesis. Finally, high-quality and high-purity calcium hexaluminate refractory raw materials with the specification required by users can be directly obtained after the secondary calcination.
Compared with other prior inventions and related technologies, the invention has the advantages and beneficial effects that:
(1) compared with other methods, the method provided by the invention has the advantages that the raw material source is relatively pure, no additive is additionally added in the production process, the purity of the raw material in the preparation process is further ensured, the refractoriness and the slag erosion resistance of the product are favorably improved, and the material quality is further improved.
(2) The two-step calcination method adopted by the invention can effectively synthesize a certain content of calcium hexaluminate in the primary calcination process and effectively prevent volume expansion caused by the generation process of calcium aluminates in different forms in the secondary calcination process. Furthermore, the prepared calcium hexaluminate material is ensured to have certain compactness and good compressive strength.
(3) The two-step calcination method adopted by the invention can effectively improve the content of calcium hexaluminate in the product (see figure 1), and compared with other methods, the product of the invention has the advantages that the phase structure composition of all the products is calcium hexaluminate, alumina, calcium oxide and other forms of calcium aluminate are not contained basically, and the composition and quality of the product are effectively guaranteed.
Drawings
FIG. 1 is an X-ray diffraction pattern of calcium hexaluminate prepared according to the present invention.
Detailed Description
The present invention will be explained in further detail below by way of examples and figures.
Example 1
In this example, alpha-Al produced in Shandong aluminum industry was used2O3The calcium hexaluminate is prepared by taking the aluminum raw material and high-quality limestone as calcium sources in all processes. Limestone is first crushed and ground to a particle size of 0.075mm using a crushing and grinding machine. Then limestone powder and industrial alpha-Al are mixed2O3Mixing the powder (with the granularity of 0.075mm) according to the mass percent of 14% and 86%. And after fully and uniformly mixing, feeding the mixed powder into a high-temperature kiln, roasting at 1500 ℃ for 30min, and cooling. And pressing the cooled powder into a cylindrical sample with the diameter of 5 cm by a press machine with the pressing force of 200 MPa. And finally, the sample is sent into the high-temperature furnace again to be roasted for 1h at 1600 ℃ and then cooled, and the high-quality calcium hexaluminate refractory raw material can be obtained. As shown in fig. 1, the X-ray diffraction pattern of calcium hexaluminate prepared in this example is that the composition of substantially all phase structures is calcium hexaluminate, and is substantially free of alumina, calcium oxide, and other forms of calcium aluminate.
The prepared calcium hexaluminate sample is subjected to performance detection, the apparent porosity is 46.09%, and the volume density is 1.98g/cm3The compressive strength is 27.02 MPa.
Example 2
In this example, alpha-Al produced in Shandong aluminum industry was used2O3The calcium hexaluminate is prepared by taking the aluminum raw material and high-quality limestone as calcium sources in all processes. Limestone is first crushed and ground to a particle size of 0.075mm using a crushing and grinding machine. Then limestone powder and industrial alpha-Al are mixed2O3Mixing the powder (with the granularity of 0.075mm) according to the mass percent of 14% and 86%. And after fully and uniformly mixing, feeding the mixed powder into a high-temperature kiln, roasting at 1500 ℃ for 30min, and cooling. And pressing the cooled powder into a cylindrical sample with the diameter of 2 cm by a press machine with the pressing force of 100 MPa. And finally, the sample is sent into the high-temperature furnace again to be roasted for 1h at 1600 ℃ and then cooled, and the high-quality calcium hexaluminate refractory raw material can be obtained. The X-ray diffraction pattern of the calcium hexaluminate prepared in this example was found to be calcium hexaluminate having essentially all of its phase structure composition and essentially no alumina, calcium oxide, and other forms of calcium aluminate.
The prepared calcium hexaluminate sample is subjected to performance detection, and the apparent porosity is 47.27 percent, and the volume density is 1.74g/cm3The compressive strength was 21.40 MPa.
Claims (3)
1. A method for preparing high-quality calcium hexaluminate refractory raw material by using a two-step roasting method is characterized in that industrial alpha-Al is adopted2O3The method for preparing the high-purity light calcium hexaluminate refractory raw material by using high-quality limestone as a calcium source as an aluminum raw material in all processes comprises the following steps: (1) crushing and mixing; (2) primary calcination; (3) pressing into blocks for molding; (4) calcining and forming;
primary calcination: feeding the mixed powder into a high-temperature kiln, roasting at 1500-1600 ℃ for 25-35 min, and cooling to form a semi-finished calcium hexaluminate powder;
and (3) briquetting and forming: according to the shape design after being fired, the semi-finished product calcium hexaluminate powder prepared in the step (2) is pressed and formed by a press machine; the molding pressure is adjusted according to the surface areas of different materials: when the maximum diameter of the molding surface is less than 2 cm, the pressing force of 80-100 MPa is adopted; when the maximum diameter of the molding surface is more than 2 cm and less than 5 cm, the pressing force of more than 100MPa and less than 200MPa is adopted;
calcining and forming: and (4) delivering the product prepared in the step (3) into a high-temperature kiln, roasting at 1500-1600 ℃ for 50-70 min, and cooling to obtain the high-quality calcium hexaluminate refractory raw material.
2. The method for preparing a high-quality calcium hexaluminate refractory raw material by using a two-step roasting method as claimed in claim 1, wherein the steps of crushing, mixing: limestone powder and industrial alpha-Al2O3The particle size of the powder is controlled below 100 meshes, and the limestone powder and industrial alpha-Al are mixed2O3Mixing the powder according to the mass percent of 14% and 86% respectively.
3. The method for preparing a high-quality calcium hexaluminate refractory raw material by using a two-step roasting method as claimed in claim 1, wherein the technical parameters of the high-quality calcium hexaluminate refractory raw material are as follows: the apparent porosity is controlled below 50%, and the volume density is 1.70g/cm3The compressive strength is 21.00MPa or more.
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| CN106892668A (en) * | 2017-03-01 | 2017-06-27 | 武汉科技大学 | A kind of calcium hexaluminate lightweight refractory material and preparation method thereof |
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| EP1178023A1 (en) * | 2000-08-04 | 2002-02-06 | Alcoa Chemie GmbH | High density refractory material containing calcium hexaluminate |
| CN101456575A (en) * | 2009-01-08 | 2009-06-17 | 上海交通大学 | Method for preparing calcium-hexaluminate ceramic powder by calcium slag |
| CN104119089A (en) * | 2014-07-07 | 2014-10-29 | 西南科技大学 | Method for low temperature preparation of lightweight calcium-hexaluminate-magnesium aluminate spinel multiphase refractory material by two step method |
| CN105585314A (en) * | 2015-12-22 | 2016-05-18 | 辽宁科技学院 | Dense calcium hexaluminate grog refractory and preparation method thereof |
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