A method for preparing high-performance foam ceramics and products prepared thereby

Abstract

The application discloses a preparation method of high-performance foam ceramic and a product prepared by the method. By introducing dolomite, lithium slag and copper tailings as raw materials, the sintering temperature of the foam ceramic is effectively reduced, and the foam ceramic is caused to form a crystal structure with diopside, anorthite and quartz as main crystal phases and a composite closed pore system in a sintering process. The unique structure and system not only significantly enhance the bending strength of the foam ceramic, ensure the stability of the structure, but also effectively maintain the high porosity characteristics of the material, so that the mechanical properties and porous properties are double optimized. The application can effectively reduce the sintering temperature, and has a positive promoting effect on improving resource utilization efficiency and environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and in particular to a preparation method of high-performance foam ceramics and a product obtained therefrom. Background Art

[0002] As a new type of porous material, foam ceramics have the characteristics of high specific surface area, low thermal conductivity, good filtration and adsorption capacity, excellent chemical stability and thermal shock resistance. These characteristics make foam ceramics have broad application potential in many fields such as construction and automobiles. By using low-cost minerals and solid waste as production raw materials, the firing temperature of foam ceramics is effectively reduced, which not only effectively promotes the recycling of resources and reduces carbon emissions, but also significantly reduces the negative impact of waste on the environment. However, the key problem that needs to be solved urgently is how to efficiently utilize these low-cost raw materials to prepare high-performance foam ceramic materials to ensure that they maintain high porosity characteristics while still having excellent flexural strength. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a method for preparing high-performance foam ceramics. By introducing dolomite, lithium slag, and copper tailings as raw materials, the sintering temperature of the foam ceramics is effectively reduced, prompting the foam ceramics to form a crystal structure with diopside, anorthite, and quartz as the main crystal phases and a composite closed-pore system during the sintering process. This ensures structural stability while effectively maintaining the material's high porosity, thereby achieving dual optimization of mechanical and porous properties. Another object of the present invention is to provide products produced using the above-mentioned preparation method.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] The present invention provides a method for preparing high-performance foam ceramics. The raw material composition of the foam ceramics is 38-52 wt% shale, 12.2-17.9 wt% dolomite, 20-23 wt% lithium slag, 15-20 wt% copper tailings, and 0.8-1.1 wt% silicon carbide. The preparation method comprises the following steps:

[0006] (1) mixing the raw materials according to the composition ratio, wet ball milling, and sieving to obtain a foam ceramic slurry;

[0007] (2) The foam ceramic slurry is dried, ground, and sieved to obtain foam ceramic powder;

[0008] (3) The green body obtained by pressing the foam ceramic powder into shape is heated to 1080-1110° C. at a rate of 4-7° C. / min for sintering, and the heat preservation time is 1-2 hours. After natural cooling, high-performance foam ceramics are obtained.

[0009] Furthermore, the chemical composition of the lithium slag of the present invention is SiO267.56-81.27wt%, Al2O36.13-13.25wt%, Fe2O30.05-0.21wt%, Na2O 0.98-3.27wt%, K2O 0.86-3.12wt%, IL 7.38-13.98wt%; the chemical composition of the copper tailings is SiO226.16-30.51wt%, Al2O32.54-6.32wt%, CaO3.18-7.36wt%, Fe2O338.56-56.27wt%, MgO 2.86-6.98wt%, Na2O 0.56-2.19wt%, K2O 0.35-1.52wt%, ZnO 0.46~2.13wt%, CuO 1.96~6.72wt%, IL 1.13~3.58wt%.

[0010] In the above scheme, in step (1) of the present invention, the ball milling treatment is carried out according to the material: ball: water = 1:2-3:1-2, and the ball milling time is 30-40 minutes. In step (2), the drying temperature is 90-100°C and the drying time is 7-10 hours. In step (3), the pressure of the pressing molding is 6-9 MPa.

[0011] The product prepared by the above-mentioned preparation method of high-performance foam ceramics has the main crystal phases of diopside, anorthite and quartz, and its flexural strength is 10.78-13.02 MPa and its bulk density is 0.81-0.95 g / cm 3 The total porosity is 60.89~64.56%, and the closed porosity is 51.24~56.73%.

[0012] The present invention has the following beneficial effects:

[0013] (1) The dolomite introduced into the formula system of the present invention will gradually and slowly release CO2 gas during the high-temperature calcination process, forming pores with smaller pores and uniform distribution inside the foam ceramic; while SiC reacts at high temperature to form pores with larger pores. The two are intertwined to form a composite closed pore system. In addition, Al2O3 can increase the melting temperature and viscosity characteristics of the liquid phase, control the size of bubbles, enhance the liquid phase's ability to seal gas, make the pore wall structure denser, and further optimize the uniformity and stability of the closed pore structure. The synergistic effect of the dolomite, SiC and Al2O3 of the present invention during the calcination process jointly promotes the formation of a composite closed pore structure, which gives the foam ceramic of the present invention the characteristics of high porosity and uniform distribution.

[0014] (2) The addition of dolomite, lithium slag and copper tailings in the present invention makes the content of calcium and magnesium in the system relatively high, and diopside (CaO·MgO·2SiO2) will be formed under high-temperature calcination. However, the amount of calcium is relatively excessive. In the process of forming diopside, the excess calcium will combine with Al2O3 and SiO2 in the system to form anorthite (CaO·Al2O3·2SiO2). Diopside, anorthite and residual quartz crystal phase together constitute the main crystal phase of foam ceramics, effectively enhancing the flexural strength of foam ceramics. The crystal structure and composite closed pore system of the foam ceramics of the present invention not only ensure its structural stability, but also effectively maintain the high porosity characteristics of the material, thereby achieving dual optimization of mechanical properties and porous properties.

[0015] (3) The lithium slag and copper tailings of the present invention are solid wastes, and shale is a low-cost raw material. The copper tailings have a high Fe2O3 content, the dolomite has high CaO and MgO contents, and the shale and lithium slag contain alkali metal and alkaline earth metal oxides, thereby forming an Fe-Ca-Mg-K-Na composite fluxing system, which facilitates uniform foaming of the product. The use of this formulation system to prepare foam ceramics can not only effectively reduce the firing temperature, but also has a positive role in improving resource utilization efficiency and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings:

[0017] Figure 1 Industrial CT images of the foam ceramics prepared in accordance with the embodiments of the present invention are shown (a: cross-sectional view; b: stereoscopic view). DETAILED DESCRIPTION

[0018] The present invention implements a method for preparing high-performance foam ceramics. The raw material composition of the foam ceramics is 38-52 wt% shale, 12.2-17.9 wt% dolomite, 20-23 wt% lithium slag, 15-20 wt% copper tailings, and 0.8-1.1 wt% silicon carbide. The chemical composition of the raw materials is shown in Table 1, and the raw material composition of each embodiment is shown in Table 2.

[0019] The preparation method comprises the following steps:

[0020] (1) After mixing the raw materials according to the above-mentioned composition ratio, ball milling is performed at a ratio of material: ball: water = 1:2-3:1-2 for 30-40 minutes, and the mixture is passed through a 60-mesh sieve to obtain a foam ceramic slurry;

[0021] (2) drying the foam ceramic slurry in an oven at 90-100° C. for 7-10 hours, grinding the slurry, and filtering the slurry through a 200-mesh sieve to obtain foam ceramic powder;

[0022] (3) The foam ceramic powder is pressed into shape at a pressure of 6 to 9 MPa for 25 seconds. The resulting green body is placed in an electric furnace and heated to 1080 to 1110°C at a rate of 4 to 7°C / min for sintering. The heat preservation time is 1 to 2 hours. After natural cooling, high-performance foam ceramics are obtained.

[0023] The process parameters of each embodiment are shown in Table 3.

[0024] Table 1 Chemical composition of raw materials used in the examples of the present invention (wt%)

[0025]

[0026] Table 2 Raw material composition (wt%) of each embodiment of the present invention

[0027]

[0028] Table 3 Process parameters of various embodiments of the present invention

[0029]

[0030] Comparative Example 1:

[0031] Four groups of experiments were conducted with no dolomite added as comparative example 1, and the remaining conditions were the same as those in Example 1, Example 2, Example 3, and Example 4.

[0032] Comparative Example 2:

[0033] Four groups of experiments were conducted with no lithium slag added as comparative example 2, and the remaining conditions were the same as those in examples 1, 2, 3, and 4.

[0034] Comparative Example 3:

[0035] Four groups of experiments were conducted with no copper tailings added as comparative example 3, and the remaining conditions were the same as those in Example 1, Example 2, Example 3, and Example 4.

[0036] Performance testing:

[0037] like Figure 1 As shown, the foam ceramics prepared in the examples of the present invention have a composite closed-pore structure. Flexural strength was measured according to GB / T17657-2013 (static flexural strength by three-point bending), while bulk density, total porosity, and closed porosity were measured according to GB / T 2997-2000. The performance indicators of the foam ceramics prepared in the examples of the present invention, as well as the average performance indicators of the foam ceramics obtained in the comparative examples, are shown in Table 4.

[0038] Table 4 Performance indicators of foam ceramics in various embodiments of the present invention and comparative examples

[0039]

Claims

1. A method for preparing high-performance foam ceramics, characterized in that: The raw material composition of the foam ceramic is 38-52 wt% of shale, 12.2-17.9 wt% of dolomite, 20-23 wt% of lithium slag, 15-20 wt% of copper tailings, and 0.8-1.1 wt% of silicon carbide; The preparation method comprises the following steps: (1) mixing the raw materials according to the composition ratio, wet ball milling, and sieving to obtain a foam ceramic slurry; (2) The foam ceramic slurry is dried, ground, and sieved to obtain foam ceramic powder; (3) The green body obtained by pressing the foam ceramic powder into shape is heated to 1080-1110° C. at a rate of 4-7° C. / min for sintering, and the heat preservation time is 1-2 hours. After natural cooling, high-performance foam ceramics are obtained.

2. The method for preparing high-performance foam ceramics according to claim 1, wherein: The chemical composition of the lithium slag is SiO2 67.56-81.27wt%, Al2O3 6.13-13.25wt%, Fe2O3 0.05-0.21wt%, Na2O 0.98-3.27wt%, K2O 0.86-3.12wt%, and IL 7.38-13.98wt%.

3. The method for preparing high-performance foam ceramics according to claim 1, wherein: The chemical composition of the copper tailings is SiO2 26.16-30.51 wt%, Al2O3 2.54-6.32 wt%, CaO 3.18-7.36 wt%, Fe2O3 38.56-56.27 wt%, MgO 2.86-6.98 wt%, Na2O 0.56-2.19 wt%, K2O 0.35-1.52 wt%, ZnO 0.46-2.13 wt%, CuO 1.96-6.72 wt%, and IL 1.13-3.58 wt%.

4. The method for preparing high-performance foam ceramics according to claim 1, wherein: In the step (1), the ball milling is performed according to the ratio of material: ball: water = 1:2-3:1-2, and the ball milling time is 30-40 minutes.

5. The method for preparing high-performance foam ceramics according to claim 1, wherein: In the step (2), the drying temperature is 90-100° C. and the drying time is 7-10 hours.

6. The method for preparing high-performance foam ceramics according to claim 1, wherein: The pressure of the compression molding in the step (3) is 6 to 9 MPa.

7. A product obtained by the method for preparing a high-performance foam ceramic according to any one of claims 1 to 6, characterized in that: The main crystal phases of the high performance foam ceramic are diopside, anorthite and quartz.

8. The product according to claim 7, characterized in that: The high-performance foam ceramic has a flexural strength of 10.78-13.02 MPa and a bulk density of 0.81-0.95 g / cm 3 The total porosity is 60.89~64.56%, and the closed porosity is 51.24~56.73%.

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