A method for preparing porous ceramics using rare earth tailings at low temperature and the resulting product.

Abstract

This invention discloses a method for preparing porous ceramics using rare earth tailings at low temperatures, and the resulting product. Utilizing the high content of alkaline flux and sulfur in rare earth tailings, the method optimizes the formulation to achieve low-temperature sintering, resulting in a high-performance product that meets porous ceramic standards. Simultaneously, it significantly improves the utilization rate of rare earth tailings, saves fuel and energy, reduces environmental pollution, and promotes the sustainable development of porous ceramic production. This invention features a simple and highly operable process, eliminating complex preparation steps, achieving waste recycling, facilitating large-scale industrial production, and further promoting the application and development of related industries.

Description

Technical Field

[0001] This invention relates to the field of porous ceramic materials technology, and in particular to a method for preparing porous ceramics using rare earth tailings at low temperature and the resulting product. Background Technology

[0002] In recent years, research on the reuse of industrial solid waste has received widespread attention in order to improve resource utilization and reduce industrial production costs. Industrial solid waste is classified into industrial production waste (such as metals, ceramics, rubber, gypsum, and glass) and mineral waste (such as tailings, coal gangue, and sand). Among them, tailings are a type of industrial solid waste with large output and low utilization rate. With the increasing pressure of environmental protection and energy conservation and emission reduction, how to improve the reuse rate of tailings resources has become an urgent problem to be solved. Currently, most existing technologies use rare earth slag or tailings to prepare permeable bricks and vitrified ceramic bricks. Although some technologies use rare earth slag as raw material to prepare porous ceramic plates, the firing temperature is high, and binders are used, making the process complex and difficult to meet the needs and development of the porous ceramic industry. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing porous ceramics using rare earth tailings at low temperatures. This method leverages the high content of alkaline flux and sulfur in rare earth tailings, and through optimized formulation, achieves low-temperature sintering to obtain products with excellent performance that meet porous ceramic standards. Simultaneously, it significantly improves the utilization rate of rare earth tailings, saves fuel and energy, and reduces environmental pollution, thus contributing to the sustainable development of porous ceramic production. Another objective of this invention is to provide products obtained using the aforementioned method for preparing porous ceramics using rare earth tailings at low temperatures.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] This invention provides a method for preparing porous ceramics using rare earth tailings at low temperature, comprising the following steps:

[0006] (1) The rare earth tailings: kaolin: sodium feldspar: potassium feldspar: boron calcium stone: silicon carbide = 65~75: 12~18: 11~16: 7~11: 6~12: 1.4~2 were mixed to obtain a mixture.

[0007] (2) The mixture is added to a ball mill and ball milled according to the mass ratio of mixture:water:ball mill = 1:1~2:1~2. The resulting slurry is sieved, dried and then ground to obtain mixed powder.

[0008] (3) The mixed powder is granulated, aged, and then pressure-formed to obtain a green body;

[0009] (4) The green body is fired at 970-1030℃ and held for 15-40 minutes, then cooled down in the furnace to produce porous ceramics.

[0010] In the above scheme, the chemical composition of the rare earth tailings of the present invention is as follows: SiO2 39.88–40.88 wt%, Al2O3 18.96–19.96 wt%, Fe2O3 1.38–2.38 wt%, TiO2 0.1–0.2 wt%, CaO 20.54–21.54 wt%, MgO 0.37–0.47 wt%, K2O 3.73–4.73 wt%, Na2O 0.83–0.93 wt%, P2O5 0.23–0.28 wt%, SO3 5.95–6.95 wt%, ZnO 0.05–0.09 wt%, Rb2O 0.4–0.5 wt%, BaO 0.11–1.21 wt%, MnO 0.29~0.39wt%, Bi2O30.12~0.16wt%, IL3.11~4.11wt%.

[0011] Further, in step (2) of the present invention, the ball milling time is 30-50 min, the mixture is passed through an 80-120 mesh sieve, and dried at 80-100℃ for 8-12 h. In step (3), 5-10 wt% water is added to the mixed powder for granulation, and the mixture is aged for 2-4 h; pressure molding is performed at 5-15 MPa for 10-20 s.

[0012] The product obtained by the above-mentioned method for preparing porous ceramics using rare earth tailings at low temperature, provided by the present invention, has the following chemical composition: SiO2 44.61–46.84 wt%, Al2O3 20.98–22.93 wt%, CaO 15.27–17.31 wt%, MgO 0.42–0.44 wt%, K2O 3.57–3.95 wt%, Na2O 1.99–2.3 wt%, Fe2O3 1.29–1.36 wt%, TiO2 0.092–0.097 wt%, P2O5 0.159–0.168 wt%, SiC 1.16–1.67 wt%, BaO 0.098–0.11 wt%, and ZnO. The porous ceramic contains 0.043–0.047 wt%, B₂O₃ 2.34–4.5 wt%, MnO 0.208–0.228 wt%, Rb₂O 0.257–0.29 wt%, and SO₃ 3.96–4.14 wt%. The main crystalline phase of the porous ceramic is anorthite; the average pore size of the porous ceramic is 33.46–34.68 μm, its water absorption rate is >10%, its flexural strength is ≥3.5 MPa, and its bulk density is ≤0.9 g / cm³. 3 Apparent porosity ≥ 30%.

[0013] The present invention has the following beneficial effects:

[0014] (1) This invention utilizes rare earth tailings rich in fluxing materials such as Ca and Mg to form a multi-component composite flux system “K2O-Na2O-CaO-MgO-B2O3” with potassium feldspar, sodium feldspar, and borate. Compared with existing porous ceramic preparation technologies, this invention has a significant low-temperature sintering effect (sintering temperature of 970-1030℃) and also significantly broadens the sintering temperature range.

[0015] (2) The present invention significantly increases the amount of rare earth tailings introduced, which not only realizes the efficient utilization of rare earth tailings resources and solves the problem of low usage of rare earth tailings, but also reduces the environmental pressure caused by the large amount of rare earth tailings wasted. Furthermore, the firing temperature is significantly reduced, which is conducive to saving energy and reducing environmental pollution. It has very important economic and social benefits and is of great significance to the sustainable development of porous ceramics production.

[0016] (3) The main raw material used in this invention, rare earth tailings, is rich in elements such as Ca, Mg and S. During the sintering process, it reacts with other raw materials to generate calcium feldspar crystals, forming the skeleton of porous ceramic materials. At the same time, silicon carbide and S in rare earth tailings are used together as foaming agents to form a reasonable distribution of large, medium and small pores, giving the material good mechanical properties.

[0017] (4) The present invention uses granulation, dry pressing and other methods to prepare porous ceramics, which is not only highly operable and saves the complicated preparation process, but also realizes the reuse of waste, which is conducive to industrial-scale production and thus promotes the application and development of related industries. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0019] Figure 1 These are photographs of the porous ceramics prepared according to embodiments of the present invention in water;

[0020] Figure 2 This is the XRD pattern of the porous ceramic prepared according to an embodiment of the present invention;

[0021] Figure 3 This is a SEM image of the porous ceramic prepared according to an embodiment of the present invention. Detailed Implementation

[0022] Example 1:

[0023] This embodiment describes a method for preparing porous ceramics using rare earth tailings at low temperature, the steps of which are as follows:

[0024] (1) The rare earth tailings: kaolin: sodium feldspar: potassium feldspar: boron calcium stone: silicon carbide = 70: 14: 15: 10: 6: 1.4 were mixed to obtain the mixture.

[0025] (2) Add the above mixture into a ball mill and ball mill for 30 minutes according to the mass ratio of mixture:water:ball mill = 1:1:1.8. After passing the slurry through an 80-mesh sieve, dry it at 80°C for 8 hours. After grinding, pass it through a 40-mesh sieve to obtain the mixed powder.

[0026] (3) Add water at a rate of 5 wt% of the mixed powder to the above mixed powder for granulation, and after aging for 2 hours, use a tablet press to hold the pressure at 5 MPa for 10 seconds to obtain the green body;

[0027] (4) The above-mentioned green body is fired at 1000℃ for 15 minutes and then cooled down in the furnace to produce porous ceramics.

[0028] The chemical composition of the rare earth tailings in this embodiment is as follows: SiO2 39.88wt%, Al2O3 18.96wt%, Fe2O3 2.38wt%, TiO2 0.2wt%, CaO 21.17wt%, MgO 0.47wt%, K2O 4.55wt%, Na2O 0.93wt%, P2O5 0.23wt%, SO3 5.95wt%, ZnO 0.05wt%, Rb2O 0.4wt%, BaO 1.21wt%, MnO 0.39wt%, Bi2O3 0.12wt%, and IL 3.11wt%.

[0029] The porous ceramic prepared in this embodiment has the following chemical composition: SiO2 46.44 wt%, Al2O3 21.93 wt%, CaO 15.28 wt%, MgO 0.417 wt%, K2O 3.509 wt%, Na2O 2.15 wt%, Fe2O3 1.29 wt%, TiO2 0.096 wt%, P2O5 0.167 wt%, SiC 1.62 wt%, BaO 0.098 wt%, ZnO 0.043 wt%, Bi2O3 2.34 wt%, MnO 0.21 wt%, Rb2O 0.27 wt%, and SO3 4.14 wt%.

[0030] Example 2:

[0031] This embodiment describes a method for preparing porous ceramics using rare earth tailings at low temperature, which differs from Embodiment 1 in that:

[0032] Step (2) Perform ball milling according to the mass ratio of material:water:ball mill = 1:1.2:1.8;

[0033] Step (3) Add water at a rate of 8 wt% of the mixed powder for granulation;

[0034] Step (4) is to be fired at 970℃ and held for 30 minutes.

[0035] Example 3:

[0036] This embodiment describes a method for preparing porous ceramics using rare earth tailings at low temperature, the steps of which are as follows:

[0037] (1) The rare earth tailings: kaolin: sodium feldspar: potassium feldspar: borocalcite: silicon carbide = 70: 14: 15: 10: 12: 2 were mixed to obtain a mixture.

[0038] (2) Add the above mixture into a ball mill and ball mill for 30 minutes according to the mass ratio of mixture:water:ball mill = 1:1.2:1.8. After passing the slurry through a 100-mesh sieve, dry it at 100℃ for 10 hours. After grinding, pass it through a 40-mesh sieve to obtain the mixed powder.

[0039] (3) Add water at a rate of 8 wt% of the mixed powder to the above mixed powder for granulation, and after aging for 3 hours, use a tablet press to hold the pressure at 8 MPa for 15 seconds to obtain the green body;

[0040] (4) The above-mentioned green body is fired at 970℃ for 30 minutes and then cooled down in the furnace to produce porous ceramics.

[0041] The chemical composition of the rare earth tailings in this embodiment is as follows: SiO2 40.28wt%, Al2O3 19.00wt%, Fe2O3 1.88wt%, TiO2 0.2wt%, CaO 20.54wt%, MgO 0.47wt%, K2O 4.55wt%, Na2O 0.50wt%, P2O5 0.25wt%, SO3 6.01wt%, ZnO 0.06wt%, Rb2O 0.4wt%, BaO 1.21wt%, MnO 0.39wt%, Bi2O3 0.15wt%, and IL 4.11wt%.

[0042] The porous ceramic prepared in this embodiment has the following chemical composition: SiO2 44.51 wt%, Al2O3 20.98 wt%, CaO 16.22 wt%, MgO 0.435 wt%, K2O 3.58 wt%, Na2O 1.99 wt%, Fe2O3 1.33 wt%, TiO2 0.092 wt%, P2O5 0.159 wt%, SiC 1.66 wt%, BaO 0.098 wt%, ZnO 0.046 wt%, Bi2O3 4.47 wt%, MnO 0.22 wt%, Rb2O 0.28 wt%, and SO3 3.93 wt%.

[0043] Example 4:

[0044] This embodiment describes a method for preparing porous ceramics using rare earth tailings at low temperature, the steps of which are as follows:

[0045] (1) The rare earth tailings: kaolin: sodium feldspar: potassium feldspar: boron calcium stone: silicon carbide = 75:14:15:10:9:1.4 were mixed to obtain the mixture.

[0046] (2) Add the above mixture into a ball mill and ball mill for 40 minutes according to the mass ratio of mixture:water:ball mill = 1:1.2:2. After passing through a 100-mesh sieve, dry at 90°C for 10 hours, grind and pass through a 40-mesh sieve to obtain mixed powder.

[0047] (3) Add water at a rate of 10 wt% of the mixed powder to the above mixed powder for granulation, and after aging for 3 hours, use a tablet press to hold the pressure at 10 MPa for 15 seconds to obtain the green body;

[0048] (4) The above-mentioned green body is fired at 1030℃ for 30 minutes and then cooled down in the furnace to produce porous ceramics.

[0049] The chemical composition of the rare earth tailings in this embodiment is as follows: SiO2 40.28wt%, Al2O3 19.28wt%, Fe2O3 1.88wt%, TiO2 0.1wt%, CaO 20.54wt%, MgO 0.47wt%, K2O 4.55wt%, Na2O 0.93wt%, P2O5 0.24wt%, SO3 6.95wt%, ZnO 0.06wt%, Rb2O 0.48wt%, BaO 0.11wt%, MnO 0.38wt%, Bi2O3 0.12wt%, and IL 3.63wt%.

[0050] The porous ceramic prepared in this embodiment has the following chemical composition: SiO2 45.42wt%, Al2O3 21.44wt%, CaO 15.99wt%, MgO 0.428wt%, K2O 3.79wt%, Na2O 2.012wt%, Fe2O3 1.35wt%, TiO2 0.097wt%, P2O5 0.168wt%, SiC 1.354wt%, BaO 0.106wt%, ZnO 0.045wt%, Bi2O3 3.31wt%, MnO 0.22wt%, Rb2O 0.29wt%, and SO3 3.98wt%.

[0051] Example 5:

[0052] This embodiment describes a method for preparing porous ceramics using rare earth tailings at low temperature, the steps of which are as follows:

[0053] (1) The rare earth tailings: kaolin: sodium feldspar: potassium feldspar: boron calcium stone: silicon carbide = 70: 14: 15: 10: 12: 1.4 were mixed to obtain the mixture.

[0054] (2) Add the above mixture into a ball mill and ball mill for 40 minutes according to the mass ratio of mixture:water:ball mill = 1:1.2:2. After passing through a 120-mesh sieve, dry at 80°C for 12 hours. After grinding, pass through a 40-mesh sieve to obtain mixed powder.

[0055] (3) Add water at a rate of 10 wt% of the mixed powder to the above mixed powder for granulation, and after aging for 4 hours, use a tablet press to hold the pressure at 10 MPa for 15 seconds to obtain the green body;

[0056] (4) The above-mentioned green body is fired at 970℃ for 40 minutes and then cooled down in the furnace to produce porous ceramics.

[0057] The chemical composition of the rare earth tailings in this embodiment is as follows: SiO2 40.88wt%, Al2O3 18.96wt%, Fe2O3 1.80wt%, TiO2 0.2wt%, CaO 20.84wt%, MgO 0.37wt%, K2O 4.05wt%, Na2O 0.93wt%, P2O5 0.27wt%, SO3 6.38wt%, ZnO 0.08wt%, Rb2O 0.48wt%, BaO 0.11wt%, MnO 0.38wt%, Bi2O3 0.16wt%, and IL 4.11wt%.

[0058] The porous ceramic prepared in this embodiment has the following chemical composition: SiO2 44.73wt%, Al2O3 21.08wt%, CaO 16.19wt%, MgO 0.437wt%, K2O 3.59wt%, Na2O 2.008wt%, Fe2O3 1.3wt%, TiO2 0.092wt%, P2O5 0.16wt%, SiC 1.219wt%, BaO 0.098wt%, ZnO 0.043wt%, Bi2O3 4.49wt%, MnO 0.21wt%, Rb2O 0.283wt%, and SO3 4.07wt%.

[0059] The porous ceramics prepared in the embodiments of the present invention, such as Figure 1 As shown, it floats on the water surface, meeting the requirements for lightweight ceramic wall panels. The diffraction peaks of the porous ceramics are consistent with the crystal phase of anorthite (PDF#89-1471) (see...). Figure 2 This indicates that the main crystalline phase of the porous ceramic is anorthite. For example... Figure 3 As shown, the porous ceramic is composed of large and small pores, with an average pore size of 33.46 μm.

[0060] The porous ceramics prepared in the embodiments of the present invention were subjected to performance tests according to the national standard GB / T 16533-1996, and the test results are shown in Table 1.

[0061] Table 1 Performance test results of porous ceramics prepared in the embodiments of the present invention

[0062]

[0063] Table 1 shows that the porous ceramics prepared in the embodiments of the present invention have good sintering performance, with a water absorption rate >10%, flexural strength ≥3.5MPa, and bulk density ≤0.9g / cm³. 3 The apparent porosity is ≥30%, meeting the requirements of the national standard GB / T23451-2009 for porous ceramics.

Claims

1. A method for preparing porous ceramics at low temperature using rare earth tailings, characterized in that... Includes the following steps: (1) The rare earth tailings were mixed according to the mass ratio of rare earth tailings: kaolinite: sodium feldspar: potassium feldspar: borocalcite: silicon carbide = 65-75: 12-18: 11-16: 7-11: 6-12: 1.4-2 to obtain a mixture. The chemical composition of the rare earth tailings was as follows: SiO2 39.88-40.88wt%, Al2O3 18.96-19.96wt%, Fe2O3 1.38-2.38wt%, TiO2 0.1-0.2wt%, CaO2 0.54-21.54wt%, MgO 0.37-0.47wt%, K2O 3.73-4.73wt%, Na2O 0.83-0.93wt%, P2O5 0.23-0.28wt%, SO3 5.95-6.95wt%, ZnO 0.05-0.09wt%, Rb2O 0.4~0.5wt%, BaO 0.11~1.21wt%, MnO 0.29~0.39wt%, Bi2O30.12~0.16wt%, IL 3.11~4.11wt%; (2) Add the mixture to a ball mill and ball mill it according to the mass ratio of mixture:water:ball mill = 1:1~2:1~2. The ball milling time is 30~50min. After passing through an 80~120 mesh sieve and drying at 80~100℃ for 8~12h, grind it to obtain the mixed powder. (3) The mixed powder is granulated, aged, and then pressure-formed to obtain a green body; (4) The green body is fired at 970-1030℃ and held for 15-40 minutes, then cooled in the furnace to obtain porous ceramics; the main crystalline phase of the porous ceramics is anorthite; the average pore size of the porous ceramics is 33.46-34.68μm, and its water absorption rate is >10%, flexural strength is ≥3.5MPa, bulk density is ≤0.9g / cm³, and apparent porosity is ≥30%.

2. The method for preparing porous ceramics using rare earth tailings at low temperature according to claim 1, characterized in that: In step (3), water of 5-10 wt% of the mixed powder is added externally to granulate the powder and aged for 2-4 hours; pressure molding is carried out at 5-15 MPa pressure for 10-20 seconds.

3. The product obtained by the method for preparing porous ceramics using rare earth tailings at low temperature as described in claim 1 or 2, characterized in that: The porous ceramic has the following chemical composition: SiO2 44.61–46.84 wt%, Al2O3 20.98–22.93 wt%, CaO 15.27–17.31 wt%, MgO 0.42–0.44 wt%, K2O 3.57–3.95 wt%, Na2O 1.99–2.3 wt%, Fe2O3 1.29–1.36 wt%, TiO2 0.092–0.097 wt%, P2O5 0.159–0.168 wt%, SiC 1.16–1.67 wt%, BaO 0.098–0.11 wt%, ZnO 0.043–0.047 wt%, B2O3 2.34–4.5 wt%, MnO 0.208–0.228 wt%, Rb2O 0.257–0.29 wt%, SO3 3.96–4.14 wt%.

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