Manufacturing method and apparatus for ultrafine rare earth oxide powder

Abstract

The present invention relates to the technical field of rare earth oxides and provides a method and apparatus for producing ultrafine rare earth oxide powder. The present invention involves introducing a rare earth salt solution, a precipitant solution, and a compressed gas into a centrifuge to carry out a precipitation reaction, obtaining a rare earth precipitate, which is then calcined to obtain ultrafine rare earth oxide powder. The present invention involves a continuous precipitation reaction in the centrifuge, where the rare earth salt solution and the precipitant solution pass through the centrifuge quickly, thereby reducing contact time and crystal growth time, thereby maintaining small particle size. The present invention also involves introducing compressed gas into the centrifuge, which significantly increases the turbulence of the precipitation reaction, helping the precipitate form crystal nuclei and making the precipitate less likely to change over time and grow. The precipitation reaction apparatus used in the present invention has a simple structure and requires a small equipment input. At the same time, the continuous reaction method improves production efficiency and yield, reducing production costs.

Description

[Technical Field]

[0001] This application claims priority from a Chinese patent application filed with the China Patent Office on December 27, 2023, with application number CN202311809888.9 and title "Method and apparatus for producing ultrafine rare earth oxide powder," the entire contents of which are incorporated herein by reference. The present invention relates to the technical field of rare earth oxides, and more particularly to a method and apparatus for producing ultrafine rare earth oxide powders. [Background technology]

[0002] Rare earth oxides refer to the oxides of 17 elements in total, including the 15 lanthanum oxides with atomic numbers 57 to 71 in the periodic table, as well as scandium (sc) and yttrium (y), which have chemical properties similar to those of lanthanum. Currently, rare earth oxides are widely used in fields such as petroleum, chemical industry, metallurgy, textiles, ceramics, glass, and permanent magnet materials.

[0003] Ultrafine rare earth oxide powders, typically powders with a particle size of 3 μm or less, have superior physical and chemical properties compared to conventional rare earth oxide powders and are widely used in high-tech materials. Their main applications include: First, as a sintering additive, adding ultrafine rare earth oxide powder during sintering of aluminum nitride ceramics reduces the sintering temperature without affecting its high density, high thermal conductivity, and oxygen content. Second, in MLCC ceramic capacitors, the dielectric constant of barium titanate ceramics, which are used as dielectric layers, has a strong temperature dependence, with large variations in the dielectric constant near the Curie temperature. To achieve better temperature stability, doping with ultrafine rare earth oxide powder can shift and lower the dielectric peak. Third, in the application of ultrafine rare earth oxide powder in the positive electrode of lithium batteries, doping with ultrafine rare earth oxide powder can effectively inhibit the migration of metal ions into the lithium layer, further inhibiting the H2 → H3 phase change and electrode polarization, improving the reversibility of the material electrode, stabilizing the material structure, and improving the cycling stability of the positive electrode material. Fourth, in the production of hot spray coatings, ultrafine rare earth oxide powder has higher sphericity, lower porosity, and better stability during metallization compared to conventional amorphous rare earth oxide powder at the micron level (particle size greater than 3 μm and less than 10 μm). As ultrafine rare earth oxide powder is widely used in the above fields, its market demand will gradually increase.

[0004] Currently, there are many methods for producing ultrafine rare earth oxide powders, mainly physical and chemical methods. Physical methods are primarily mechanical milling (using ball mills, sand mills, or airflow mills). Rare earth oxide ultrafine powders produced by physical methods have two drawbacks: first, the product is amorphous; and second, the ball milling media introduces impurities, contaminating the product. Chemical methods include the sol-gel method, hydrothermal method, microemulsion method, and precipitation method. The organic solvents used in the sol-gel method are expensive, resulting in high production costs. The hydrothermal method requires high temperatures and pressures for the reaction, making it difficult to ensure operational safety, and the required equipment is expensive and requires high investment costs. The microemulsion method makes it very difficult to control the emulsion state, making product separation difficult, and this method is difficult to apply to mass production. In the precipitation method, rare earth salts are mainly precipitated using a precipitating agent. Currently, the precipitating agent is usually added directly to the rare earth salt solution to carry out the reaction. This makes it very difficult to control the reaction conditions, making the operation difficult and making it difficult to obtain ultrafine rare earth oxide powders that meet the size requirements.

[0005] For the above reasons, the current methods for producing ultrafine rare earth oxide powders have problems such as difficult operation, high costs, and low production efficiency, making industrial production difficult. In order to solve these problems and promote the wider application of ultrafine rare earth oxide powders, a new production method is urgently needed. Summary of the Invention [Problem to be solved by the invention]

[0006] In view of this, the present invention provides a method and apparatus for producing ultrafine rare earth oxide powder, which is simple to operate, low cost, allows for continuous production, and has high production efficiency. [Means for solving the problem]

[0007] To achieve the above objectives, the present invention provides the following technical solutions: A method for producing ultrafine rare earth oxide powder, comprising: providing a precipitation reaction apparatus that is a centrifugal separator, the centrifugal separator including a centrifugal pump body having a raw material inlet and a product sample solution outlet; introducing the rare earth salt solution, the precipitant solution, and the compressed gas into a centrifugal separator through a raw material inlet to carry out a precipitation reaction and obtain a rare earth precipitate; D. Calcining the rare earth precipitate 50 Obtaining ultrafine rare earth oxide powder with a particle size of ≦3 μm.

[0008] Preferably, the rare earth salt in the rare earth salt solution includes one or more of rare earth chlorides and nitrates, the concentration of the rare earth salt solution is 0.1 to 0.5 mol / L, and the flow rate of the rare earth salt solution is 0.2 to 3 m 3 / h.

[0009] Preferably, the precipitant in the precipitant solution contains one or more of oxalic acid, ammonium bicarbonate, sodium hydroxide, and aqueous ammonia, the concentration of the precipitant solution is 10 to 100 g / L, and the flow rate of the precipitant solution is 0.2 to 3 m 3 / h.

[0010] Preferably, the compressed gas is one or more of compressed air, compressed nitrogen gas, compressed carbon dioxide, and compressed oxygen, and the pressure of the compressed gas is 0.1 to 0.8 MPa.

[0011] Preferably, in the precipitation reaction, the centrifugal separator has a centrifugal rotation speed of 1000 to 3000 rpm.

[0012] Preferably, the centrifugal pump body includes a pump shell and an impeller, the raw material inlet of the centrifugal pump body is located in the center of the pump shell on one side opposite the impeller axis, and the sample solution outlet of the centrifugal pump body, which is the product, is located on the side wall of the pump shell.

[0013] Preferably, the raw material inlet is in communication with a raw material feed pipe, the raw material feed pipe being a sleeve tube, the sleeve tube including an inner layer pipe and an outer layer pipe, the inner layer pipe being used to introduce a rare earth salt solution or a precipitant solution, the outer layer pipe being used to introduce a rare earth salt solution or a precipitant solution, and the solutions introduced from the inner layer pipe and the outer layer pipe being different; Preferably, the centrifugal separator also includes a motor and a cooling system, the drive shaft of the motor being connected to the centrifugal pump body, and the cooling system being installed outside the drive shaft of the motor.

[0014] One end of the inner pipe extends from the outer pipe, and the extending portion communicates with a branch pipe, which is used to introduce compressed gas.

[0015] Preferably, the D of the ultrafine rare earth oxide powder 50 The particle size is 0.5 to 3 μm.

[0016] The present invention also provides an apparatus for use in the production method according to the above solution, the apparatus being a precipitation reaction apparatus, the precipitation reaction apparatus being a centrifugal separator, the centrifugal separator including a motor, a centrifugal pump body, and a cooling system, the drive shaft of the motor being connected to the centrifugal pump body, and the cooling system being installed outside the drive shaft of the motor; a raw material inlet and a product sample solution outlet are provided in the centrifugal pump body, the centrifugal pump body including a pump shell and an impeller, the raw material inlet is located in the center of the pump shell on one side opposite to the impeller axis, and the product sample solution outlet is located on a side wall of the pump shell; the raw material inlet is in communication with a raw material feed pipe, the raw material feed pipe being a sleeve tube, the sleeve tube including an inner layer pipe and an outer layer pipe, the inner layer pipe being used to introduce a rare earth salt solution or a precipitant solution, the outer layer pipe being used to introduce a rare earth salt solution or a precipitant solution, and the solutions introduced from the inner layer pipe and the outer layer pipe being different; One end of the inner pipe extends from the outer pipe, and the extending portion communicates with a branch pipe, which is used to introduce compressed gas.

[0017] The present invention provides a method for producing ultrafine rare earth oxide powder, which comprises the steps of providing a precipitation reaction apparatus, which is a centrifugal separator, including a centrifugal pump body having a raw material inlet and a sample solution outlet, introducing a rare earth salt solution, a precipitant solution, and a compressed gas into the centrifugal separator through the raw material inlet to carry out a precipitation reaction and obtain a rare earth precipitate, and calcining the rare earth precipitate to obtain a D 50 and obtaining ultrafine rare earth oxide powder with a particle size of 3 μm or less. The present invention involves carrying out a continuous precipitation reaction in a centrifugal separator, and the rare earth salt solution and precipitant solution passing through the centrifugal separator quickly can reduce the contact time and shorten the crystal growth time, thereby maintaining small particle size. At the same time, the present invention also includes introducing compressed gas into the centrifugal separator, which can greatly increase the degree of turbulence of the precipitation reaction, which helps the precipitate to form crystal nuclei and makes the precipitate less likely to grow over time. Furthermore, the solubility product of the rare earth salt and precipitant for the precipitation reaction is very small, generally 10 -20 From 10 -30 The reaction is very fast, and the two raw materials can be fully reacted under centrifugation conditions, which can further improve the reaction rate, thereby reducing the crystal growth time and ensuring that the reaction is fully carried out. In addition, the production method provided by the present invention is a continuous reaction, which can improve production efficiency and yield and reduce production costs. [Effects of the Invention]

[0018] Furthermore, the rare earth salts and precipitants used in the present invention are all common raw materials in the rare earth industry, with wide supply sources and low costs.

[0019] Furthermore, the present invention also makes it possible to adjust the particle size of the ultrafine rare earth oxide by controlling the flow rates of the rare earth salt solution and the precipitant solution.

[0020] The present invention also provides an apparatus for use in the production method described in the above solution. The precipitation reactor used in the present invention has a simple structure, small equipment input, high production efficiency and yield, and low production cost. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a top view of a precipitation reactor according to the present invention. [Figure 2] FIG. 1A is a cross-sectional view of the plane A-A of FIG. [Figure 3] FIG. 2 is a particle size distribution diagram of the ultrafine yttrium oxide powder produced in Example 1. [Figure 4] FIG. 1 is an SEM image of the ultrafine yttrium oxide powder produced in Example 1. [Figure 5] FIG. 2 is a particle size distribution diagram of the ultrafine yttrium oxide powder produced in Example 2. [Figure 6] FIG. 2 is an SEM image of the ultrafine yttrium oxide powder produced in Example 2. [Figure 7] FIG. 2 is a particle size distribution diagram of the ultrafine yttrium oxide powder produced in Example 3. [Figure 8] FIG. 2 is an SEM image of the ultrafine yttrium oxide powder produced in Example 3. [Figure 9] FIG. 1 is a particle size distribution diagram of the ultrafine lutetium oxide powder produced in Example 4. [Figure 10] FIG. 1 is an SEM image of the ultrafine lutetium oxide powder produced in Example 4. [Figure 11] FIG. 2 is a particle size distribution diagram of the yttrium oxide powder produced in Comparative Example 1. [Figure 12] FIG. 2 is an SEM image of the yttrium oxide powder produced in Comparative Example 1. [Figure 13] FIG. 1 is a particle size distribution diagram of the yttrium oxide powder produced in Comparative Example 2. [Figure 14] FIG. 2 is an SEM image of the yttrium oxide powder produced in Comparative Example 2. [Figure 15] FIG. 10 is a particle size distribution diagram of the erbium oxide powder produced in Comparative Example 3. [Figure 16] FIG. 1 is an SEM image of the erbium oxide powder produced in Comparative Example 3. [Figure 17] FIG. 10 is a particle size distribution diagram of the lutetium oxide powder produced in Comparative Example 4. [Figure 18] FIG. 1 is an SEM image of the lutetium oxide powder produced in Comparative Example 4. [Figure 19] FIG. 10 is a particle size distribution diagram of the yttrium oxide powder produced in Comparative Example 5. [Figure 20] FIG. 1 is an SEM image of the yttrium oxide powder produced in Comparative Example 5. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention provides a method for producing ultrafine rare earth oxide powder, providing a precipitation reaction apparatus that is a centrifugal separator, the centrifugal separator including a centrifugal pump body having a raw material inlet and a product sample solution outlet; introducing the rare earth salt solution, the precipitant solution, and the compressed gas into a centrifugal separator through a raw material inlet to carry out a precipitation reaction and obtain a rare earth precipitate; D. Calcining the rare earth precipitate 50 Obtaining ultrafine rare earth oxide powder with a particle size of ≦3 μm.

[0023] First, the precipitation reaction apparatus of the present invention will be described. Figure 1 is a top view of the precipitation reaction apparatus of the present invention, and Figure 2 is a cross-sectional view taken along the line A-A in Figure 1.

[0024] The precipitation reaction apparatus provided by the present invention is a centrifugal separator, which includes a centrifugal pump body, in which a raw material inlet and a product sample solution outlet are installed, and which includes a pump shell and an impeller, in which the raw material inlet of the centrifugal pump body is located in the center of the pump shell on one side opposite to the impeller axis, and the product sample solution outlet of the centrifugal pump body is located on the side wall of the pump shell, and the position of the product sample solution outlet of the centrifugal pump body is preferably higher than the raw material inlet.

[0025] In the present invention, the raw material inlet is connected to a raw material supply pipe, the raw material supply pipe being a sleeve tube, the sleeve tube including an inner pipe and an outer pipe, the inner pipe being used to introduce a rare earth salt solution or a precipitant solution, and the outer pipe being used to introduce a rare earth salt solution or a precipitant solution, and the solutions introduced from the inner pipe and the outer pipe being different. One end of the inner pipe extends from the outer pipe, and the extending portion is connected to a branch pipe, and the branch pipe is used to introduce compressed gas.

[0026] In the present invention, the inlet of the inner layer pipe is referred to as the first liquid inlet, a liquid inlet is installed on the side wall of the outer layer pipe and is referred to as the second liquid inlet, and the inlet on the branch pipe is referred to as the gas inlet. In a specific embodiment of the present invention, a liquid flow meter is preferably installed in the first liquid inlet and the second liquid inlet pipe, respectively, and a gas flow meter is preferably installed in the gas inlet pipe.

[0027] The present invention does not have any special requirements for the capacity of the centrifugal pump body, which can be selected according to actual needs, and is preferably 2 to 8 L. In a specific embodiment of the present invention, the precipitation reaction contact time can be controlled according to the flow rates of the rare earth salt solution and the precipitant solution and the capacity of the centrifugal pump body.

[0028] In the present invention, the centrifugal separator also includes a motor and a cooling system, the drive shaft of the motor is connected to the centrifugal pump body, specifically, is connected to the impeller of the centrifugal pump body by tightening, when the motor is started, the drive shaft transmits power to the impeller, the cooling system is installed outside the drive shaft of the motor, the present invention does not have any special requirements for the structure of the motor and the cooling system, and those known in the art can be used.

[0029] The manufacturing method of the present invention will be described below.

[0030] A rare earth salt solution, a precipitant solution, and a compressed gas are introduced into a centrifugal separator through a raw material inlet to carry out a precipitation reaction, thereby obtaining a rare earth precipitate. In the present invention, the rare earth salt in the rare earth salt solution preferably comprises one or more of rare earth chlorides and nitrates. The present invention does not require any specific rare earth element in the rare earth salt, and any rare earth element may be used, preferably one or more of yttrium, erbium, and lutetium. In a specific embodiment of the present invention, the rare earth salt is preferably one or more of yttrium chloride, erbium chloride, and lutetium nitrate.

[0031] In the present invention, the concentration of the rare earth salt solution is preferably 0.1 to 0.5 mol / L, more preferably 0.2 to 0.3 mol / L, and the flow rate of the rare earth salt solution is preferably 0.2 to 3 m 3 / h, more preferably 0.5 to 2.5 m 3 / h.

[0032] In the present invention, the precipitant in the precipitant solution preferably contains one or more of oxalic acid, ammonium bicarbonate, sodium hydroxide, and aqueous ammonia, the concentration of the precipitant solution is preferably 10 to 100 g / L, more preferably 20 to 80 g / L, and the flow rate of the precipitant solution is preferably 0.2 to 3 m 3 / h, more preferably 0.5 to 2.5 m 3 / h.

[0033] In the present invention, the compressed gas is introduced through a gas inlet, and the rare earth salt solution and the precipitant solution are preferably introduced through the first liquid inlet or the second liquid inlet, respectively, or through the second liquid inlet and the first liquid inlet, respectively. That is, the present invention does not require specific inlets for the rare earth salt solution and the precipitant solution, and the first liquid inlet and the second liquid inlet can be selected arbitrarily as long as they are introduced into the centrifugal separator simultaneously through different liquid inlets.

[0034] In the present invention, the flow rate ratio of the rare earth salt solution to the precipitant solution is preferably 1:(1 to 1.2), more preferably 1:(1 to 1.1).

[0035] In a specific embodiment of the present invention, the particle size of the obtained ultrafine rare earth oxide powder is preferably adjusted by controlling the flow rates of the rare earth solution and the precipitant solution. Specifically, the higher the flow rates of the rare earth solution and the precipitant solution, the smaller the particle size of the obtained ultrafine rare earth oxide powder.

[0036] In the present invention, the compressed gas is preferably one or more of compressed air, compressed nitrogen gas, compressed carbon dioxide, and compressed oxygen, and the pressure of the compressed gas is 0.1 to 0.8 MPa, preferably 0.2 to 0.5 MPa. In the present invention, controlling the pressure of the compressed gas within the above range ensures that the compressed gas is introduced into a centrifugal separator. In the present invention, when the compressed gas is introduced into the centrifugal separator and the centrifugal separator rotates at high speed, the liquid and gas all rotate around the inner wall of the centrifugal pump, and the bubbles are mixed into the liquid, increasing the gas-liquid interface for reaction. At the same time, the bubbles continuously burst, increasing the stirring intensity of the reaction, which helps form crystal nuclei in the precipitate and makes the precipitate less likely to change and grow over time.

[0037] In the present invention, in the precipitation reaction, the centrifugal rotation speed (ie, the rotation speed of the motor) of the centrifugal separator is preferably 1000 to 3000 rpm, more preferably 2000 to 3000 rpm.

[0038] In the present invention, the precipitation reaction may be carried out at room temperature.

[0039] In a specific embodiment of the present invention, the motor is preferably powered on first, and then the rare earth salt solution, precipitant solution, and compressed gas are simultaneously introduced into the centrifuge to react, and the product sample solution is received from the product sample solution outlet. After obtaining the product sample solution, the present invention preferably separates and washes the solid product therein to obtain a rare earth precipitate, which is preferably one or more of rare earth oxalate, rare earth carbonate, and rare earth hydroxide depending on the precipitant used.

[0040] After obtaining the rare earth precipitate, the present invention calcines the rare earth precipitate to obtain ultrafine rare earth oxide powder. In the present invention, the calcination is preferably performed at a temperature of 800 to 1000°C for a time of 2 to 8 hours.

[0041] In the present invention, the D of the ultrafine rare earth oxide powder 50 The particle size is ≦3 μm, preferably 0.5 to 3 μm.

[0042] The following describes the technical solutions of the present invention clearly and completely with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only some of the embodiments of the present invention, not all of the embodiments, and all other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without any creative efforts fall within the scope of protection of the present invention.

[0043] The structure of the precipitation reaction apparatus used in the following examples is shown in Figures 1 and 2, where the capacity of the centrifugal pump body is 2L.

[0044] Example 1 The precipitation reactor was used to produce ultrafine yttrium oxide powder. After the reactor was turned on, the yttrium chloride solution and the oxalic acid solution were introduced into the centrifugal pump through the first and second liquid inlets, respectively. The concentration of the yttrium chloride solution was 0.2 mol / L, and the flow rate was 1 m 3 / h, the concentration of the oxalic acid solution is 45 g / L, and the flow rate is 1.05 m 3The reaction temperature was room temperature, and compressed air was introduced into the centrifugal pump through the gas inlet. The compressed air pressure was 0.2 MPa, and the motor speed was 1500 rpm. The sample solution was received from the outlet of the centrifugal pump. The solid product in the sample solution was separated and washed to obtain yttrium oxalate. The obtained yttrium oxalate was calcined at 950°C for 4 hours to obtain ultrafine yttrium oxide powder. 50 The particle size was 0.86 μm.

[0045] FIG. 3 is a particle size distribution diagram of the yttrium oxide ultrafine powder obtained in Example 1, Table 1 is a particle size distribution table, and FIG. 4 is an SEM image of the yttrium oxide ultrafine powder obtained in Example 1.

[0046] [Table 1] Particle size distribution table of the ultrafine yttrium oxide powder obtained in Example 1

[0047] As can be seen from FIGS. 3 and 4 and Table 1, the particle size of the ultrafine yttrium oxide powder produced in Example 1 is uniform and fine.

[0048] Example 2 A precipitation reactor was used to produce ultrafine yttrium oxide powder. After the reactor was turned on, the yttrium chloride solution and the ammonium bicarbonate solution were introduced into the centrifugal pump through the first and second liquid inlets, respectively. The concentration of the yttrium chloride solution was 0.16 mol / L, and the flow rate was 2.7 m 3 / h, the concentration of the ammonium bicarbonate solution is 20 g / L, and the flow rate is 2.8 m 3 The reaction temperature was room temperature, and compressed air was introduced into the centrifugal pump through the gas inlet. The compressed air pressure was 0.3 MPa, and the motor rotation speed was 1000 rpm. The sample solution was received from the outlet of the centrifugal pump. The solid product in the sample solution was separated and washed to obtain yttrium carbonate. The obtained yttrium carbonate was calcined at 850°C for 6 hours to obtain ultrafine yttrium oxide powder.50 The particle size was 0.77 μm.

[0049] FIG. 5 is a particle size distribution diagram of the yttrium oxide ultrafine powder obtained in Example 2, Table 2 is a particle size distribution table, and FIG. 6 is an SEM image of the yttrium oxide ultrafine powder obtained in Example 2.

[0050] [Table 2] Particle size distribution table of the ultrafine yttrium oxide powder obtained in Example 2

[0051] As can be seen from FIGS. 5 and 6 and Table 2, the particle size of the ultrafine yttrium oxide powder produced in Example 2 is uniform and fine.

[0052] Example 3 The ultrafine erbium oxide was produced using a precipitation reactor: after turning on the power of the reactor, the erbium chloride solution and the oxalic acid solution were introduced into the centrifugal pump through the first and second liquid inlets, respectively, where the concentration of the erbium chloride solution was 0.25 mol / L and the flow rate was 2 m 3 / h, the concentration of the oxalic acid solution is 50 g / L, and the flow rate is 2 m 3 The reaction temperature was room temperature, and compressed nitrogen gas was introduced into the centrifugal pump through the gas inlet. The pressure of the compressed nitrogen gas was 0.1 MPa, and the motor speed was 2000 rpm. The sample solution was received from the outlet of the centrifugal pump. The solid product in the sample solution was separated and washed to obtain erbium oxalate. The obtained erbium oxalate was calcined at 900°C for 4 hours to obtain ultrafine yttrium oxide powder. 50 The particle size was 0.69 μm. The clear liquid obtained by filtering the product sample solution was added dropwise to oxalic acid, but no precipitate was produced, indicating that the precipitation reaction was more complete.

[0053] FIG. 7 is a particle size distribution diagram of the yttrium oxide ultrafine powder obtained in Example 3, Table 3 is a particle size distribution table, and FIG. 8 is an SEM image of the yttrium oxide ultrafine powder obtained in Example 3.

[0054] [Table 3] Particle size distribution table of the yttrium oxide ultrafine powder obtained in Example 3

[0055] As can be seen from FIGS. 7 and 8 and Table 3, the particle size of the ultrafine yttrium oxide powder produced in Example 3 is uniform and fine.

[0056] Example 4 Ultrafine lutetium oxide was produced using a precipitation reactor: after the power of the reactor was turned on, the lutetium nitrate solution and the oxalic acid solution were introduced into the centrifugal pump through the first and second liquid inlets, respectively, where the concentration of the lutetium nitrate solution was 0.3 mol / L and the flow rate was 0.5 m 3 / h, the concentration of the oxalic acid solution is 60 g / L, and the flow rate is 0.55 m 3 The reaction temperature was room temperature. At the same time, compressed air was introduced into the centrifugal pump through the gas inlet. The compressed air pressure was 0.25 MPa and the motor speed was 2200 rpm. The sample solution was received from the outlet of the centrifugal pump. The solid product in the sample solution was separated and washed to obtain lutetium oxalate. The obtained lutetium oxalate was calcined at 950°C for 3 hours to obtain ultrafine lutetium oxide powder. 50 The particle size was 0.82 μm.

[0057] FIG. 9 is a particle size distribution diagram of the ultrafine lutetium oxide powder obtained in Example 4, Table 4 is a particle size distribution table, and FIG. 10 is an SEM image of the ultrafine lutetium oxide powder obtained in Example 4.

[0058] [Table 4] Particle size distribution table of the ultrafine lutetium oxide powder obtained in Example 4

[0059] As can be seen from FIGS. 9 and 10 and Table 4, the particle size of the ultrafine lutetium oxide powder produced in Example 4 is uniform and fine.

[0060] Comparative Example 1 In the reactor, the yttrium chloride solution and the oxalic acid solution were co-precipitated. The yttrium chloride solution and the oxalic acid solution were added to the reactor under the control of a flow meter. The concentration of the yttrium chloride solution was 0.2 mol / L, and the flow rate was 1 m 3 / h, the concentration of the oxalic acid solution is 45 g / L, and the flow rate is 1.05 m 3 The reaction time was 1 hour (the reaction time was calculated from the start of the material supply), and the reaction temperature was room temperature. The solid product in the sample solution was separated and washed to obtain yttrium oxalate. The obtained yttrium oxalate was calcined at 950 °C for 4 hours to obtain yttrium oxide powder. 50 The particle size was 5.37 μm.

[0061] FIG. 11 is a particle size distribution diagram of the yttrium oxide powder obtained in Comparative Example 1, Table 5 is a particle size distribution table, and FIG. 12 is an SEM image of the yttrium oxide powder obtained in Comparative Example 1.

[0062] [Table 5] Particle size distribution table of yttrium oxide powder obtained in Comparative Example 1

[0063] As can be seen from the data in FIGS. 11 and 12 and Table 5, the yttrium oxide powder produced in Comparative Example 1 has a large particle size and cannot meet the requirements for ultrafine rare earth oxide powder.

[0064] Comparative Example 2 In the reactor, the yttrium chloride solution and the ammonium bicarbonate solution were co-precipitated. The yttrium chloride solution and the ammonium bicarbonate solution were added to the reactor under the control of a flow meter. The concentration of the yttrium chloride solution was 0.16 mol / L, and the flow rate was 2.7 m 3 / h, the ammonium bicarbonate solution concentration was 20 g / L, and the flow rate was 2.8 m 3The reaction time was 2 hours (the reaction time was calculated from the start of the material supply), and the reaction temperature was room temperature. The solid product in the sample solution was separated and washed to obtain yttrium carbonate. The obtained yttrium carbonate was calcined at 850°C for 6 hours to obtain yttrium oxide powder. 50 The particle size was 5.50 μm.

[0065] FIG. 13 is a particle size distribution diagram of the yttrium oxide powder obtained in Comparative Example 2, Table 6 is a particle size distribution table, and FIG. 14 is an SEM image of the yttrium oxide powder obtained in Comparative Example 2.

[0066] [Table 6] Particle size distribution table of yttrium oxide powder obtained in Comparative Example 2

[0067] As can be seen from the data in FIGS. 13 and 14 and Table 6, the yttrium oxide powder produced in Comparative Example 2 has a large particle size and cannot meet the requirements for ultrafine rare earth oxide powder.

[0068] Comparative Example 3 In the reactor, the erbium chloride solution and the oxalic acid solution were subjected to coprecipitation reaction. The erbium chloride solution and the oxalic acid solution were all added to the reactor under the control of a flow meter. The concentration of the erbium chloride solution was 0.25 mol / L, and the flow rate was 2 m 3 / h, the oxalic acid solution concentration was 50 g / L, and the flow rate was 2 m 3 The reaction time was 0.5 hours (the reaction time was calculated from the start of the material supply), and the reaction temperature was room temperature. The solid product in the sample solution was separated and washed to obtain erbium oxalate. The obtained erbium oxalate was calcined at 900°C for 4 hours to obtain erbium oxide powder. 50 The particle size was 8.32 μm.

[0069] FIG. 15 is a particle size distribution diagram of the erbium oxide powder obtained in Comparative Example 3, Table 7 is a particle size distribution table, and FIG. 16 is an SEM image of the erbium oxide powder obtained in Comparative Example 3.

[0070] [Table 7] Particle size distribution table of erbium oxide powder obtained in Comparative Example 3

[0071] As can be seen from the data in FIGS. 15 and 16 and Table 7, the erbium oxide powder produced in Comparative Example 3 has a large particle size and cannot meet the requirements for ultrafine rare earth oxide powder.

[0072] Comparative Example 4 In the reactor, the lutetium nitrate solution and the oxalic acid solution were co-precipitated. The lutetium nitrate solution and the oxalic acid solution were added to the reactor under the control of a flow meter. The concentration of the lutetium nitrate solution was 0.3 mol / L, and the flow rate was 0.5 m 3 / h, the concentration of the oxalic acid solution is 60 g / L, and the flow rate is 0.55 m 3 The reaction time was 3 hours (the reaction time was calculated from the start of the material supply), and the reaction temperature was room temperature. The solid product in the sample solution was separated and washed to obtain lutetium oxalate. The obtained lutetium oxalate was calcined at 950°C for 3 hours to obtain lutetium oxide powder. 50 The particle size was 7.31 μm.

[0073] FIG. 17 is a particle size distribution diagram of the lutetium oxide powder obtained in Comparative Example 4, Table 8 is a particle size distribution table, and FIG. 18 is an SEM image of the lutetium oxide powder obtained in Comparative Example 4.

[0074] [Table 8] Particle size distribution table of lutetium oxide powder obtained in Comparative Example 4

[0075] As can be seen from the data in FIGS. 17 to 18 and Table 8, the lutetium oxide powder produced in Comparative Example 4 has a large particle size and cannot meet the requirements for ultrafine rare earth oxide powder.

[0076] Comparative Example 5 The other conditions were the same as in Example 1, except that the introduction of compressed gas was omitted. 50 The particle size was 3.97 μm.

[0077] FIG. 19 is a particle size distribution diagram of the yttrium oxide powder obtained in Comparative Example 5, Table 9 is a particle size distribution table, and FIG. 20 is an SEM image of the yttrium oxide powder obtained in Comparative Example 5.

[0078] [Table 9] Particle size distribution table of yttrium oxide powder obtained in Comparative Example 5

[0079] As can be seen from the data in Figures 19-20 and Table 9, the particle size of the resulting yttrium oxide powder was larger after omitting the introduction of compressed air, which explains why the introduction of compressed air increases the turbulence of the reaction, helps to form crystal nuclei in the precipitate, and makes the precipitate less likely to grow over time.

[0080] The above is merely a preferred embodiment of the present invention, and those skilled in the art may make further improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also fall within the scope of protection of the present invention. [Explanation of symbols]

[0081] In Figs. 1 and 2 1-Motor 2-Water cooling system 3-Pump shell 4-impeller 5-Outer layer piping 6-Inner layer piping 7-1st liquid inlet 8-Second liquid inlet 9-Gas inlet 10 - Product sample solution outlet

Claims

1. A method for producing ultrafine rare earth oxide powder, comprising: Precipitating the rare earth salt solution, the precipitant solution, and the compressed gas under centrifugal conditions to obtain a rare earth precipitate; The rare earth precipitate is calcined, and D ５０ and obtaining an ultrafine rare earth oxide powder having a particle size of 3 μm or less.

2. providing a precipitation reaction apparatus that is a centrifugal separator, the centrifugal separator including a centrifugal pump body having a raw material inlet and a product sample solution outlet; introducing the rare earth salt solution, the precipitant solution, and the compressed gas into a centrifugal separator through a raw material inlet to carry out a precipitation reaction and obtain a rare earth precipitate; The rare earth precipitate is calcined, and D ５０ 2. The method according to claim 1, further comprising the step of obtaining an ultrafine rare earth oxide powder having a particle size of ≦3 μm.

3. The rare earth salt in the rare earth salt solution includes one or more of rare earth chlorides and nitrates, the concentration of the rare earth salt solution is 0.1 to 0.5 mol / L, and the flow rate of the rare earth salt solution is 0.2 to 3 m ３ 3. The method according to claim 2, wherein the reaction temperature is 1000° C. / h.

4. 4. The method according to claim 3, wherein the rare earth element in the rare earth salt is one or more of yttrium, erbium, and lutetium.

5. The precipitant in the precipitant solution contains one or more of oxalic acid, ammonium bicarbonate, sodium hydroxide, and aqueous ammonia, the concentration of the precipitant solution is 10 to 100 g / L, and the flow rate of the precipitant solution is 0.2 to 3 m ３ 3. The method according to claim 2, wherein the reaction temperature is 1000° C. / h.

6. 6. The method according to claim 3, wherein the flow rate ratio of the rare earth salt solution to the precipitant solution is 1:(1 to 1.2).

7. 3. The manufacturing method according to claim 2, wherein the compressed gas is one or more of compressed air, compressed nitrogen gas, compressed carbon dioxide, and compressed oxygen, and the pressure of the compressed gas is 0.1 to 0.8 MPa.

8. 3. The method according to claim 2, wherein the centrifugal separator rotates at a speed of 1,000 to 3,000 rpm during the precipitation reaction.

9. 3. The method according to claim 2, wherein the centrifugal pump body includes a pump shell and an impeller, the raw material inlet of the centrifugal pump body is located in the center of the pump shell on one side opposite to the impeller axis, and the sample solution outlet of the centrifugal pump body, which is the product, is located on a side wall of the pump shell.

10. the raw material inlet is in communication with a raw material feed pipe, the raw material feed pipe being a sleeve tube, the sleeve tube including an inner layer pipe and an outer layer pipe, the inner layer pipe being used to introduce a rare earth salt solution or a precipitant solution, the outer layer pipe being used to introduce a rare earth salt solution or a precipitant solution, and the solutions introduced from the inner layer pipe and the outer layer pipe being different; 10. The manufacturing method according to claim 2 or 9, wherein one end of the inner layer pipe extends from the outer layer pipe, and the extending portion is connected to a branch pipe, and the branch pipe is used to introduce compressed gas.

11. 3. The manufacturing method according to claim 2, wherein the centrifugal separator also includes a motor and a cooling system, the drive shaft of the motor being connected to the centrifugal pump body, and the cooling system being installed outside the drive shaft of the motor.

12. 2. The method according to claim 1, wherein the firing is performed at a temperature of 800 to 1000° C. for 2 to 8 hours.

13. D of the rare earth oxide ultrafine powder ５０ 2. The method according to claim 1, wherein the particle size is 0.5 to 3 μm.

14. An apparatus for use in the production method according to any one of claims 1 to 13, wherein the apparatus is a precipitation reaction apparatus, the precipitation reaction apparatus is a centrifugal separator, the centrifugal separator includes a motor, a centrifugal pump body, and a cooling system, a drive shaft of the motor is connected to the centrifugal pump body, and the cooling system is installed outside the drive shaft of the motor; a raw material inlet and a product sample solution outlet are provided in the centrifugal pump body, the centrifugal pump body including a pump shell and an impeller, the raw material inlet is located in the center of the pump shell on one side opposite to the impeller axis, and the product sample solution outlet is located on a side wall of the pump shell; the raw material inlet is in communication with a raw material feed pipe, the raw material feed pipe being a sleeve tube, the sleeve tube including an inner layer pipe and an outer layer pipe, the inner layer pipe being used to introduce a rare earth salt solution or a precipitant solution, the outer layer pipe being used to introduce a rare earth salt solution or a precipitant solution, and the solutions introduced from the inner layer pipe and the outer layer pipe being different; The manufacturing method according to any one of claims 1 to 13, characterized in that one end of the inner layer piping extends from the outer layer piping, and the extending portion communicates with a branch piping, and the branch piping is used to introduce compressed gas.

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