Infrared radiation coating prepared from rare earth waste material, and preparation method and use thereof

Abstract

The application discloses an infrared radiation coating prepared from rare earth waste, a preparation method and application thereof. The preparation method of the infrared radiation coating comprises the following steps: (1) forming rare earth waste particles from rare earth waste containing rare earth polishing powder waste and rare earth crystal waste; the amount of the rare earth polishing powder waste is 60-100 parts by weight, and the amount of the rare earth crystal waste is 1-30 parts by weight; (2) heat treating the rare earth waste particles to obtain calcined particles; (3) forming calcined rare earth powder from the calcined particles; grinding the calcined rare earth powder, water and a dispersing agent to form a calcined rare earth slurry; (4) mixing the calcined rare earth slurry and a binder to obtain the infrared radiation coating. The preparation method uses the rare earth waste as raw material, reduces the cost of the infrared radiation coating, and the obtained infrared radiation coating has high emissivity in the 1-22 mu m wave band.

Description

TECHNICAL FIELD

[0001] The present application relates to an infrared radiation coating prepared from rare earth waste and a preparation method and use thereof. BACKGROUND

[0002] The working temperature of industrial kiln is generally above 1000℃, and the heat preservation performance and thermal radiation performance of the refractory material of the furnace body determine the thermal energy utilization efficiency and energy saving rate of the kiln. The working layer of the kiln has a relatively high thermal conductivity and a relatively low far infrared emissivity, and the far infrared emissivity will further decrease with the increase of the furnace temperature. This makes a large amount of heat transferred outward through the refractory material, and the temperature and temperature rising rate of the internal heated material are in a relatively low state, and a large amount of heat is conducted away by the waste gas and the refractory material, so that the thermal energy utilization rate is low.

[0003] Forming a rare earth infrared radiation coating on the surface of the refractory material of the high-temperature furnace can increase the blackness of the heated surface, improve the absorption and radiation efficiency of infrared rays, strengthen the radiation heat transfer in the furnace, and improve the uniformity of the furnace temperature and the use efficiency of thermal energy. However, as a strategic resource and non-renewable resource, rare earth needs to be used more reasonably.

[0004] At present, a large amount of rare earth waste will be generated in industry. The rare earth waste includes rare earth polishing powder waste, rare earth catalyst waste, and rare earth crystal waste. The market demand for rare earth polishing powder shows a trend of rising year by year, and a large amount of rare earth polishing powder waste will be generated every year. The rare earth polishing powder still contains 30-90wt% of rare earth oxides after failure. The rare earth catalyst waste is also a large amount of rare earth waste generated at present. According to the relevant reports, the global rare earth catalyst waste generated every year is about several hundred tons. The rare earth crystal waste is mainly generated in the process of crystal production and processing. If the crystal growth is not ideal, has flaws, the performance does not reach the technical standard due to the influence of production conditions and cannot be remelted, and some leftover materials, cutting materials and the like are generated in the crystal processing process. If the rare earth waste is left or filled, not only the resource will be wasted, but also the environment will be polluted; if the rare earth waste can be utilized, great economic value will be generated. SUMMARY

[0005] An object of the present application is to provide a preparation method of an infrared radiation coating prepared from rare earth waste, which can utilize waste materials, reduce the cost of the infrared radiation coating, and the obtained infrared radiation coating has a relatively high emissivity in the 1-22μm wave band. Further, the infrared radiation coating prepared by the method has good heat resistance and can be used for the coating of high-temperature industrial kiln. Another object of the present application is to provide an infrared radiation coating. Still another object of the present application is to provide the use of the infrared radiation coating.

[0006] The object of the present application is achieved by the following scheme.

[0007] In one aspect, the present application provides a method for preparing an infrared radiation coating using rare earth waste, comprising the following steps:

[0008] (1) forming rare earth waste particles from rare earth waste comprising rare earth polishing powder waste and rare earth crystal waste; the amount of the rare earth polishing powder waste is 60-100 parts by weight, and the amount of the rare earth crystal waste is 1-30 parts by weight;

[0009] (2) heat treating the rare earth waste particles to obtain calcined particles;

[0010] (3) forming calcined rare earth powder from the calcined particles; grinding the calcined rare earth powder, water, and a dispersing agent to form a calcined rare earth slurry;

[0011] (4) mixing the calcined rare earth slurry and a binder to obtain the infrared radiation coating.

[0012] The main component of the rare earth polishing powder is cerium oxide, which can be divided into high-grade polishing powder and low-grade polishing powder. The content of cerium oxide in the high-grade polishing powder is more than 80 wt%, which is suitable for high-speed polishing of precision optical lenses. The content of cerium oxide in the low-grade polishing powder is generally 55-65 wt%, which is suitable for polishing of optical glasses, flat glasses, and metal equipment.

[0013] In the present application, the amount of the rare earth polishing powder waste is 60-100 parts by weight; preferably 70-95 parts by weight.

[0014] The content of rare earth elements in the rare earth polishing powder waste is 60-90 wt%; in some embodiments, 70-80 wt%.

[0015] The content of La in the rare earth polishing powder waste can be 20-50 wt%, in some embodiments, 25-40 wt%, and in other embodiments, 30-35 wt%, based on the total mass of rare earth elements in the rare earth polishing powder waste; the content of Ce in the rare earth polishing powder waste can be 50-75 wt%, in some embodiments, 60-70 wt%, and in other embodiments, 65-67 wt%.

[0016] The rare earth polishing powder waste can also contain Fe. The content of Fe can be 0.01-5 wt%. In some embodiments, the content of Fe is 0.05-0.5 wt%. In other embodiments, the content of Fe is 0.08-0.2 wt%.

[0017] The content of Ca in the rare earth polishing powder waste can be <3 wt%. In some embodiments, the content of Ca is 0.05-1 wt%; in other embodiments, the content of Ca is 0.1-0.8 wt%; and in still other embodiments, the content of Ca is 0.3-0.5 wt%.

[0018] The content of Al in the rare earth polishing powder waste can be < 3 wt%. In some embodiments, the content of Al is 0.05-1 wt%; in other embodiments, the content of Al is 0.1-0.8 wt%; in still other embodiments, the content of Al is 0.3-0.5 wt%.

[0019] The content of Mg in the rare earth polishing powder waste is < 3 wt%. In some embodiments, the content of Mg is 0.05-1 wt%; in other embodiments, the content of Mg is 0.1-0.8 wt%; in still other embodiments, the content of Mg is 0.3-0.5 wt%.

[0020] The rare earth polishing powder waste can contain Si. The content of Si can be 0.1-1.5 wt%; in some embodiments, 0.5-1.2 wt%; in other embodiments, 0.7-1 wt%.

[0021] In some embodiments, the rare earth polishing powder waste can be spherical particles with a particle size of 2-5 μm.

[0022] In some embodiments, the lanthanum in the rare earth polishing powder waste enters the crystal lattice of cerium. CeO2 is a cubic crystal structure with a crystal size of 5.4109*5.4109*5.4109 A.

[0023] The amount of the rare earth crystal waste is 1-30 parts by weight; preferably 1-20 parts by weight; more preferably 5-10 parts by weight.

[0024] The content of rare earth elements in the rare earth crystal waste is 20-50 wt%; in some embodiments, 30-45 wt%; in other embodiments, 35-40 wt%.

[0025] The content of La in the rare earth crystal waste can be 80-99 wt%, in some embodiments, 85-97 wt%, in other embodiments, 90-96 wt%, based on the total mass of rare earth elements in the rare earth crystal waste; the content of Ce in the rare earth crystal waste can be 1-7 wt%, in some embodiments, 2-6 wt%, in other embodiments, 3-5 wt%.

[0026] The rare earth crystal waste can also contain Si. The content of Si can be 0.1-4 wt%; in some embodiments, 0.5-2 wt%; in other embodiments, 0.8-1 wt%.

[0027] In some embodiments, the rare earth crystal waste is a rare earth scintillation crystal waste, which is mainly a rare earth bromide with a small amount of Si incorporated during crystal growth.

[0028] In some embodiments, the rare earth waste material can also include rare earth catalyst waste material. Currently, the commercialized rare earth catalysts mainly include petroleum cracking catalysts and automobile exhaust purification catalysts. The rare earth elements in the petroleum cracking catalysts can enhance the activity and stability of the zeolite catalysts as a cocatalyst material, and the content of the rare earth elements in the petroleum cracking catalysts is generally more than 2 wt%. The rare earth elements in the automobile exhaust purification catalysts mainly include cerium oxide, praseodymium oxide and lanthanum oxide or mixtures thereof.

[0029] According to the preparation method of the present application, preferably, the rare earth waste material also includes rare earth catalyst waste material, and the amount of the rare earth catalyst waste material is 1-25 parts by weight. More preferably, the amount of the rare earth catalyst waste material is 5-20 parts by weight. In some embodiments, the amount of the rare earth catalyst waste material is 10-15 parts by weight.

[0030] The content of the rare earth elements in the rare earth catalyst waste material can be 0.05-10 wt%, in some embodiments, 1-5 wt%, and in other embodiments, 2-3 wt%.

[0031] Based on the total mass of the rare earth elements in the rare earth catalyst waste material, the content of La in the rare earth catalyst waste material can be 20-50 wt%, in some embodiments, 25-40 wt%, and in other embodiments, 35-38 wt%; and the content of Ce in the rare earth catalyst waste material can be 50-75 wt%, in some embodiments, 55-70 wt%, and in other embodiments, 60-65 wt%.

[0032] The rare earth catalyst waste material can also include one or more of Fe and Zr elements.

[0033] The content of Fe can be 0.1-5 wt%, in some embodiments, 0.1-2 wt%, in other embodiments, 0.3-1 wt%, and in further embodiments, 0.5-0.8 wt%.

[0034] The content of Zr can be 3-15 wt%, in some embodiments, 5-12 wt%, and in further embodiments, 7-10 wt%.

[0035] In the rare earth catalyst waste material, the content of Ca is <3 wt%. In some embodiments, the content of Ca is 0.05-1 wt%. In other embodiments, the content of Ca is 0.1-0.8 wt%. In further embodiments, the content of Ca is 0.3-0.5 wt%.

[0036] In rare earth catalyst waste, the Al content is <3 wt%. In some embodiments, the Al content is 1-3 wt%; in other embodiments, the Al content is 2-2.8 wt%; and in still other embodiments, the Al content is 2.2-2.5 wt%.

[0037] In rare earth catalyst waste, the Mg content is <3 wt%. In some embodiments, the Mg content is 0.1–2 wt%. In other embodiments, the Mg content is 0.5–1.5 wt%. In still other embodiments, the Mg content is 0.8–1 wt%.

[0038] Rare earth catalyst waste may contain Si. The Si content may be 60–95 wt%; in some embodiments, it is 70–90 wt%; and in other embodiments, it is 80–85 wt%.

[0039] According to the preparation method of the present invention, preferably, the rare earth element content in the rare earth polishing powder waste is 60-90 wt%, the rare earth element content in the rare earth catalyst waste is 0.05-10 wt%, and the rare earth element content in the rare earth crystal waste is 20-50 wt%.

[0040] According to the preparation method of the present invention, preferably, based on the total mass of rare earth elements in the rare earth polishing powder waste, the content of La in the rare earth polishing powder waste is 20-50 wt%, and the content of Ce in the rare earth polishing powder waste is 50-75 wt%; based on the total mass of rare earth elements in the rare earth catalyst waste, the content of La in the rare earth catalyst waste is 20-50 wt%, and the content of Ce in the rare earth catalyst waste is 50-75 wt%; based on the total mass of rare earth elements in the rare earth crystal waste, the content of La in the rare earth crystal waste is 80-99 wt%, and the content of Ce in the rare earth crystal waste is 1-7 wt%.

[0041] According to the preparation method of the present invention, preferably, the rare earth polishing powder waste also contains 0.05-1 wt% Ca, 0.05-1 wt% Al, 0.05-1 wt% Mg, 0.01-0.8 wt% Fe and 0.1-1.5 wt% Si; the rare earth catalyst waste also contains 0.05-1 wt% Ca, 1-3 wt% Al, 0.1-2 wt% Mg, 0.1-2 wt% Fe, 3-15 wt% Zr and 60-95 wt% Si; and the rare earth crystal waste also contains 0.1-4 wt% Si.

[0042] Using the above-mentioned raw materials and controlling the amount of each raw material within the above-mentioned range is beneficial to improving the infrared emissivity of infrared radiation coatings and improving their heat resistance.

[0043] According to the preparation method of the present invention, preferably, rare earth waste is formed into rare earth waste slurry, and the rare earth waste slurry is spray-dried to form rare earth waste particles; the particle size of rare earth waste in the rare earth waste slurry is ≤60μm; the mass ratio of rare earth waste to water in the rare earth waste slurry is (70~140):150.

[0044] This invention involves granulating rare earth waste, which gives the rare earth waste better flowability and improves the uniformity of mixing various rare earth wastes; moreover, the granular material generates less dust, making it more environmentally friendly and operator-friendly.

[0045] In some embodiments, the rare earth waste slurry is sprayed into a drying chamber using a spraying device, causing the droplets formed by the rare earth waste slurry to come into contact with hot air, evaporating the water in the droplets and forming rare earth waste particles. A cyclone separator is then used to separate the rare earth waste particles from the airflow. In some embodiments, the separated rare earth waste particles are further sieved to remove any rare earth waste that has not formed particles. The mesh size of the sieve can be determined based on the particle size of the rare earth waste in the rare earth waste slurry.

[0046] The particle size of the rare earth waste in the rare earth waste slurry is ≤60μm; preferably, the particle size is ≤50μm. In some embodiments, the particle size of the rare earth waste in the rare earth waste slurry is 20-40μm. This helps to improve the uniformity of the rare earth waste slurry.

[0047] In the rare earth waste slurry, the mass ratio of rare earth waste to water is (70-140):150; preferably (90-120):150; more preferably (100-110):150. This helps to improve the uniformity of the rare earth waste slurry and helps to form rare earth waste particles of appropriate size.

[0048] Rare earth waste can be ground with water to form a rare earth waste slurry. Grinding can be carried out in a ball mill.

[0049] In some embodiments, the rare earth waste is first crushed into coarse powder, and then the coarse powder is ground with water to form a rare earth waste slurry. The crushing can be carried out in a pulverizer. The particle size of the coarse rare earth waste powder can be ≤200 mesh; preferably, ≤250 mesh; more preferably, ≤300 mesh. This helps to form a slurry with good uniformity.

[0050] In some embodiments, the rare earth waste is first dried and then pulverized. Drying reduces the moisture content of the rare earth waste, which facilitates subsequent pulverization and other steps, and improves the uniformity of the rare earth powder. The moisture content of the dried rare earth waste is ≤10wt%; preferably, ≤8wt%; more preferably, ≤5wt%. The rare earth waste can be dried at 100–150°C; preferably 105–120°C.

[0051] According to the preparation method of the present invention, preferably, the rare earth waste is dried until the moisture content of the rare earth waste is ≤10wt% to obtain dried rare earth waste; the dried rare earth waste is crushed to form rare earth coarse powder; the rare earth coarse powder is ground with water to obtain rare earth waste slurry.

[0052] According to the preparation method of the present invention, preferably, the heat treatment temperature is 1000-1500℃ and the heat treatment time is 1-5h;

[0053] The calcined rare earth powder, water, and dispersant are ground until the particle size of the calcined rare earth powder is below 30 μm to form a calcined rare earth slurry; the particle size of the calcined rare earth powder is ≤200 mesh, the mass ratio of the calcined rare earth powder to water is (0.5~4):1, and the dispersant is 1~10‰ of the mass of the calcined rare earth powder.

[0054] The mass ratio of calcined rare earth slurry to binder is (1-5):2.

[0055] The preferred heat treatment temperature is 1200–1300℃. The preferred heat treatment time is 2–4 hours. After heat treatment, natural cooling can be used for cooling.

[0056] The heating rate from the initial temperature to the heat treatment temperature can be 5–20 °C / min; preferably 10–15 °C / min.

[0057] Heat treatment can be carried out in a muffle furnace.

[0058] The particle size of the calcined rare earth powder is ≤200 mesh; preferably, the particle size is ≤250 mesh; more preferably, the particle size is ≤300 mesh. The calcined particles can be crushed first, and then pulverized to obtain the calcined rare earth powder.

[0059] In this invention, calcined rare earth powder, water, and a dispersant are ground until the particle size of the calcined rare earth powder is below 30 μm; preferably below 20 μm; more preferably below 10 μm, to form a calcined rare earth slurry. The grinding can be carried out in a ball mill.

[0060] The preferred mass ratio of calcined rare earth powder to water is (1-3):1; more preferably (2-2.5):1.

[0061] The dispersant may be selected from one or more of modified styrene-maleic acid copolymer and sodium polyacrylate. In some embodiments, the dispersant is selected from one or more of BYK-190 and RT-8040. According to one embodiment of the present invention, the dispersant is BYK-190.

[0062] The amount of dispersant can be 1 to 10‰ of the mass of the calcined rare earth powder; preferably 3 to 8‰; more preferably 5 to 7‰.

[0063] The binder can be selected from silica sol, aluminum sol, zirconium sol, and aluminum dihydrogen phosphate solution. According to one embodiment of the present invention, the binder is an aluminum dihydrogen phosphate solution.

[0064] The SiO2 content in the silica sol can be 20–42 wt%; in some embodiments, it is 30–40 wt%.

[0065] The Al2O3 content in the aluminum sol can be 5–18 wt%; in some embodiments it is 10–15 wt%.

[0066] The ZrO2 content in the zirconium sol can be 5–23 wt%; in some embodiments it is 10–20 wt%.

[0067] The aluminum dihydrogen phosphate content in the aluminum dihydrogen phosphate solution can be 35–65 wt%; in some embodiments, it is 45–55 wt%.

[0068] The mass ratio of calcined rare earth slurry to binder can be (1-5):2; preferably (2-4):2; more preferably (3-3.5):2.

[0069] The calcined rare earth slurry and binder are stirred to ensure uniform mixing. The stirring time can be 10–60 min; preferably 15–30 min.

[0070] On the other hand, the present invention provides an infrared radiation coating, which is prepared by the above-described preparation method.

[0071] The infrared radiation coating has an emissivity of ≥0.9 in the 1–22 μm band; preferably, the emissivity is ≥0.95; more preferably, the emissivity is ≥0.97.

[0072] The infrared radiation coating has an emissivity of ≥0.9 in the 3-5μm band; preferably, the emissivity is ≥0.94; more preferably, the emissivity is ≥0.97.

[0073] In another aspect, the present invention provides the use of the above-mentioned infrared radiation coating as a kiln coating.

[0074] This invention uses rare earth waste as raw material, reducing the cost of infrared radiation coatings and enabling the harmless treatment of various rare earth wastes, turning waste into treasure. The infrared radiation coating prepared by the method of this invention exhibits high emissivity in both the 1-22 μm and 3-5 μm wavelength bands. This infrared radiation coating also possesses good heat resistance and can be used under high-temperature conditions. Attached Figure Description

[0075] Figure 1 This is an SEM image of the rare earth polishing powder waste used in the example.

[0076] Figure 2 The image shows the XRD pattern of the rare earth polishing powder waste used in the example. Detailed Implementation

[0077] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0078] The raw materials are described below:

[0079] SEM image of rare earth polishing powder waste as shown below Figure 1 As shown. By Figure 1 It can be seen that the rare earth polishing powder waste consists of near-spherical particles with a particle size between 2 and 5 μm. The rare earth polishing powder waste was purchased from Lianyungang Gaopin Renewable Resources Co., Ltd., and is expired polishing powder waste used for polishing mobile phone back panels. The XRD pattern of the rare earth polishing powder waste is shown below. Figure 2 As shown. By Figure 2 It can be seen that CeO2 in rare earth polishing powder waste has a cubic crystal structure with crystal dimensions of 5.4109*5.4109*5.4109 Å, and lanthanum is present inside the CeO2 crystal lattice. The contents of some elements in rare earth polishing powder waste are shown in Table 1.

[0080] The rare earth crystal waste is anhydrous rare earth halide-doped cerium waste produced by the Tianjin Branch of Baotou Steel Rare Earth Research Institute. Its main component is cerium-doped lanthanum bromide. The content of some elements in the rare earth crystal waste is shown in Table 1.

[0081] The rare earth catalyst waste was purchased from Lianyungang Gaopin Renewable Resources Co., Ltd., and consisted of degraded automotive exhaust catalysts. The content of some elements in the rare earth catalyst waste is shown in Table 1.

[0082] Table 1

[0083] Element class Rare earth polishing powder waste Rare earth catalyst waste Rare earth crystal waste RE / wt% 71.99 2.3 37.33 La / wt% 34.13 35.22 95.25 Ce / wt% 65.87 64.78 4.75 Ca / wt% 0.35 0.37 — Al / wt% 0.37 2.46 — Mg / wt% 0.33 0.84 — Fe / wt% 0.1 0.52 — Zr / wt% — 7.05 — Ti / wt% — — — Si / wt% 0.8 84.2 0.8

[0084] Note: The total rare earth content in Table 1 was tested using EDTA titration, and the content of each element was tested using ICP-AES.

[0085] The dispersant is BYK-190.

[0086] The binder is: aluminum dihydrogen phosphate solution (aluminum dihydrogen phosphate content is 50±5wt%).

[0087] The testing method is described below:

[0088] Emissivity: Tested at 25℃ using an IR-2 dual-band emissivity meter.

[0089] Heat resistance: Infrared radiation coating is applied to bricks with a thickness of 200-300 μm. The bricks coated with infrared radiation coating are treated at 1200℃ for 15 minutes, then quickly removed and placed in water to cool. The coating is then observed for cracking or peeling.

[0090] Examples 1 to 5

[0091] Rare earth waste was dried at 105℃ until its moisture content was less than 5 wt%, yielding dried rare earth waste. The dried rare earth waste was then pulverized using a pulverizer to form coarse powder with a particle size less than 300 mesh. This coarse powder was mixed with 150 parts by weight of water and then ground in a ball mill to obtain a rare earth waste slurry. The particle size of the rare earth waste in the slurry was 20–40 μm. The rare earth waste slurry was sprayed into a drying chamber using a spray device, causing the droplets to contact with hot air, evaporating the water in the droplets and forming rare earth waste particles. A cyclone separator was used to separate the rare earth waste particles from the airflow. The particles were then passed through a 300-mesh sieve to remove any unformed particles.

[0092] The sieved rare earth waste particles were placed in a muffle furnace and heated from the initial temperature to 1200℃ at a heating rate of 10℃ / min. The temperature was held for 3 hours and then allowed to cool naturally to obtain calcined particles.

[0093] The calcined particles were crushed using a crusher, and then pulverized to below 300 mesh using a pulverizer to obtain calcined rare earth powder. The calcined rare earth powder, water, and dispersant were then ground in a ball mill until the particle size of the calcined rare earth powder was below 10 μm to obtain a calcined rare earth slurry. The mass ratio of calcined rare earth powder to water was 2:1. The dispersant was 5‰ of the mass of the calcined rare earth powder.

[0094] The calcined rare earth slurry and binder were stirred for 20 minutes to obtain an infrared radiation coating. The mass ratio of the calcined rare earth slurry to the binder was 3:2.

[0095] The composition of rare earth waste is shown in Table 2, and the performance of the obtained infrared radiation coating is shown in Table 2.

[0096] Table 2

[0097]

[0098] Comparative Example 1

[0099] Except for replacing the rare earth waste with 62 parts by weight of lanthanum oxide and 38 parts by weight of cerium oxide, the rest is the same as in Example 1, as detailed below:

[0100] 62 parts by weight of cerium oxide and 38 parts by weight of lanthanum oxide were dried at 105°C until the moisture content of the rare earth oxides was less than 5 wt%, yielding dried rare earth oxides. The dried rare earth oxides were then pulverized using a pulverizer to form coarse rare earth oxide powder with a particle size less than 300 mesh. The coarse rare earth oxide powder was mixed with 150 parts by weight of water and then ground in a ball mill to obtain a rare earth oxide slurry. The particle size of the rare earth oxides in the slurry was 20–40 μm. The rare earth oxide slurry was sprayed into a drying chamber using a spray device, allowing the droplets formed to contact with hot air, causing the water in the droplets to evaporate and form rare earth oxide particles. A cyclone separator was used to separate the rare earth oxide particles from the airflow. The rare earth oxide particles were then passed through a 300-mesh sieve to remove any rare earth oxides that did not form particles.

[0101] The sieved rare earth oxide particles were placed in a muffle furnace and heated from the initial temperature to 1200℃ at a heating rate of 10℃ / min. The temperature was held for 3 hours and then allowed to cool naturally to obtain calcined particles.

[0102] The calcined particles were crushed using a crusher, and then pulverized to below 300 mesh using a pulverizer to obtain calcined rare earth powder. The calcined rare earth powder, water, and dispersant were then ground in a ball mill until the particle size of the calcined rare earth powder was below 10 μm to obtain a calcined rare earth slurry. The mass ratio of calcined rare earth powder to water was 2:1. The dispersant was 5‰ of the mass of the calcined rare earth powder.

[0103] The calcined rare earth slurry and binder were stirred for 20 minutes to obtain an infrared radiation coating. The mass ratio of the calcined rare earth slurry to the binder was 3:2.

[0104] The infrared radiation coating has an emissivity of 0.933 at room temperature in the 1–22 μm wavelength band and 0.927 at room temperature in the 3–5 μm wavelength band. Heat resistance: No cracking or peeling observed.

[0105] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for preparing an infrared radiation coating using rare earth waste, characterized in that, Includes the following steps: (1) Rare earth waste is formed into rare earth waste slurry, and the rare earth waste slurry is spray-dried to form rare earth waste particles; the particle size of rare earth waste in the rare earth waste slurry is ≤60μm; the mass ratio of rare earth waste to water in the rare earth waste slurry is (70~140):

150. The rare earth waste consists of rare earth polishing powder waste and rare earth crystal waste; the amount of rare earth polishing powder waste is 95-100 parts by weight, and the amount of rare earth crystal waste is 5-10 parts by weight; the rare earth element content in the rare earth polishing powder waste is 70-80 wt%, and the rare earth element content in the rare earth crystal waste is 30-45 wt%; based on the total mass of rare earth elements in the rare earth crystal waste, the La content in the rare earth crystal waste is 90-99 wt%, and the Ce content is 1-7 wt%; based on the total mass of rare earth elements in the rare earth polishing powder waste, the La content in the rare earth polishing powder waste is 20-50 wt%, and the Ce content is 50-75 wt%. (2) Heat-treat rare earth waste particles to obtain calcined particles; (3) The calcined particles are formed into calcined rare earth powder; the calcined rare earth powder, water and dispersant are ground to form calcined rare earth slurry; (4) Mix the calcined rare earth slurry and binder to obtain an infrared radiation coating; The infrared radiation coating has an emissivity of ≥0.97 in the 1–22 μm band.

2. The preparation method according to claim 1, characterized in that, The rare earth polishing powder waste also contains 0.05–1 wt% Ca, 0.05–1 wt% Al, 0.05–1 wt% Mg, 0.01–0.8 wt% Fe and 0.1–1.5 wt% Si; the rare earth crystal waste also contains 0.1–4 wt% Si.

3. The preparation method according to claim 1, characterized in that, The rare earth waste is dried until the moisture content is ≤10wt% to obtain dried rare earth waste; the dried rare earth waste is crushed to form rare earth waste coarse powder; the rare earth waste coarse powder is ground with water to obtain rare earth waste slurry.

4. The preparation method according to claim 1, characterized in that, The heat treatment temperature is 1000–1500℃, and the heat treatment time is 1–5 hours. The calcined rare earth powder, water, and dispersant are ground until the particle size of the calcined rare earth powder is below 30 μm to form a calcined rare earth slurry; the particle size of the calcined rare earth powder is ≤200 mesh, the mass ratio of the calcined rare earth powder to water is (0.5~4):1, and the dispersant is 1~10‰ of the mass of the calcined rare earth powder. The mass ratio of calcined rare earth slurry to binder is (1-5):

2.

5. An infrared radiation coating, characterized in that, The infrared radiation coating is obtained by the preparation method described in any one of claims 1 to 4.

6. The use of the infrared radiation coating according to claim 5 as a kiln coating.

Images