Method and device for preparing superfine rare earth oxide powder

Abstract

The present invention relates to the technical field of rare earth oxides and provides a method and device for preparing superfine rare earth oxide powder. According to the present invention, a rare earth salt solution, a precipitant solution, and a compressed gas are introduced into a centrifugal device for a precipitation reaction to obtain a rare earth precipitate, and then the rare earth precipitate is calcined to obtain the superfine rare earth oxide powder. In the present invention, a continuous precipitation reaction is carried out in the centrifugal device, and the rare earth salt solution and the precipitant solution rapidly pass through the centrifugal device, so that the contact time can be shortened, the crystal growth time is shortened, and therefore a small particle state is maintained. In addition, according to the present invention, by introducing the compressed gas into the centrifugal device, the degree of disorder of the precipitation reaction can be greatly increased, facilitating the formation of a crystal nucleus from the precipitate, thus making the precipitate less prone to aging and growth. The precipitation reaction device used in the present invention is simple in structure and low in device investment; in addition, the continuous reaction method can improve the production efficiency and the yield and reduce production cost.

Description

A method and device for preparing ultrafine rare earth oxide powder

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 27, 2023, with application number CN202311809888.9 and invention name “A method and device for preparing ultrafine rare earth oxide powder”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of rare earth oxides, and in particular to a method and device for preparing ultrafine rare earth oxide powder. Background Art

[0003] Rare earth oxides (REOs) are oxides of 17 elements, including the 15 lanthanide elements with atomic numbers 57 to 71 in the periodic table, as well as scandium (Sc) and yttrium (Y), which have similar chemical properties to the lanthanides. Currently, REOs are widely used in the fields of petroleum, chemical engineering, metallurgy, textiles, ceramics, glass, and permanent magnets.

[0004] Ultrafine rare earth oxide powders typically refer to powders with a particle size of 3μm or less. Compared to conventional rare earth oxide powders, they possess superior physical and chemical properties and are widely used in high-tech materials. The main applications of ultrafine rare earth oxide powders are as follows: First, as a sintering aid, during the sintering process of aluminum nitride ceramics, the addition of ultrafine rare earth oxide powders can reduce the sintering temperature without affecting the high density, high thermal conductivity, and oxygen content of the ceramics. Second, in MLCC ceramic capacitors, the dielectric constant of barium titanate ceramics, which serves as the dielectric layer, has a strong temperature dependence, with a significant jump in dielectric constant near the Curie temperature. To achieve better temperature stability, doping with ultrafine rare earth oxide powders can achieve dielectric peak shift and voltage peak effects. Third, in lithium battery cathodes, doping with ultrafine rare earth oxide powders can effectively inhibit the migration of transition metal ions into the lithium layer, further suppressing the H2→H3 phase transition and electrode polarization, thereby improving the reversibility of the material electrode, stabilizing the material structure, and enhancing the cycling stability of the cathode material. Fourth, for the preparation of thermal spray coatings, ultrafine rare earth oxide powders offer higher sphericity, lower porosity, and improved stability during spraying compared to conventional micron-sized amorphous rare earth oxide powders (particle size greater than 3 μm and less than or equal to 10 μm). With the widespread application of ultrafine rare earth oxide powders in these areas, market demand is also increasing.

[0005] Currently, there are numerous methods for preparing ultrafine rare earth oxide powders, primarily physical and chemical. Physical methods primarily involve mechanical pulverization (using ball mills, sand mills, and airflow mills). Ultrafine rare earth oxide powders produced by these methods have two drawbacks: first, the product is amorphous, and second, impurities introduced into the milling medium can contaminate the product. Chemical methods include sol-gel, hydrothermal, microemulsion, and precipitation. The sol-gel method uses expensive organic solvents, resulting in high production costs. The hydrothermal method requires high temperatures and pressures, making operational safety difficult to guarantee, and the equipment required expensive, resulting in a very high investment cost. The microemulsion method is difficult to control the state of the emulsion, making product separation difficult and prohibitive for large-scale production. Precipitation methods primarily involve precipitating rare earth salts using a precipitant. Currently, this method typically involves directly adding the precipitant to a rare earth salt solution. This requires stringent control of reaction conditions, making operation difficult and making it difficult to obtain ultrafine rare earth oxide powders of the desired size.

[0006] In summary, the current methods for preparing ultrafine rare earth oxide powders all have problems such as difficult operation, high cost, and low production efficiency, making them difficult to carry out industrial production. There is an urgent need to provide a new preparation method to solve the above problems and promote the further widespread application of ultrafine rare earth oxide powders.

[0007] Summary of the Invention

[0008] In view of this, the present invention provides a method and apparatus for preparing ultrafine rare earth oxide powder. The preparation method provided by the present invention is simple to operate, low in cost, capable of continuous production, and high in production efficiency.

[0009] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0010] A method for preparing ultrafine rare earth oxide powder comprises the following steps:

[0011] A precipitation reaction device is provided; the precipitation reaction device is a centrifugal device, the centrifugal device includes a centrifugal pump body, and the centrifugal pump body is provided with a raw material inlet and a product liquid outlet;

[0012] Passing a rare earth salt solution, a precipitant solution and compressed gas into a centrifugal device from a raw material inlet to carry out a precipitation reaction to obtain a rare earth precipitate;

[0013] The rare earth precipitate is calcined to obtain ultrafine rare earth oxide powder; the ultrafine rare earth oxide powder has a D 50 Particle size ≤3μm.

[0014] Preferably, the rare earth salt in the rare earth salt solution includes one or more of rare earth chloride and rare earth nitrate; the concentration of the rare earth salt solution is 0.1-0.5 mol / L; the flow rate of the rare earth salt solution is 0.2-3 m3 / h.

[0015] Preferably, the precipitant in the precipitant solution includes one or more of oxalic acid, ammonium bicarbonate, sodium hydroxide and ammonia water; the concentration of the precipitant solution is 10 to 100 g / L; the flow rate of the precipitant solution is 0.2 to 3 m 3 / h.

[0016] Preferably, the compressed gas is one or more of compressed air, compressed nitrogen, compressed carbon dioxide and compressed oxygen; and the pressure of the compressed gas is 0.1 to 0.8 MPa.

[0017] Preferably, in the precipitation reaction, the centrifugal speed of the centrifugal device is 1000 to 3000 rpm.

[0018] Preferably, the centrifugal pump body includes a pump casing and an impeller, the raw material inlet of the centrifugal pump body is located at the center of the pump casing on the side opposite to the impeller axis; the product liquid outlet of the centrifugal pump body is located on the side wall of the pump casing.

[0019] Preferably, the raw material inlet is connected to the raw material input pipe, and the raw material input pipe is a casing, and the casing includes an inner layer pipeline and an outer layer pipeline; the inner layer pipeline is used to pass the rare earth salt solution or the precipitant solution, and the outer layer pipeline is used to pass the rare earth salt solution or the precipitant solution, and the solutions passed into the inner layer pipeline and the outer layer pipeline are different;

[0020] Preferably, the centrifugal device further includes a motor and a cooling system; the drive shaft of the motor is connected to the centrifugal pump body; and the cooling system is arranged on the outside of the drive shaft of the motor.

[0021] One end of the inner layer pipeline extends from the outer layer pipeline, and the extended part is communicated with the branch pipeline, and the branch pipeline is used to introduce compressed gas.

[0022] Preferably, the D of the ultrafine rare earth oxide powder is 50 The particle size is 0.5~3μm.

[0023] The present invention also provides a device used in the preparation method described in the above scheme, wherein the device is a precipitation reaction device, and the precipitation reaction device is a centrifugal device; the centrifugal device includes a motor, a centrifugal pump body, and a cooling system; the drive shaft of the motor is connected to the centrifugal pump body; the cooling system is arranged outside the drive shaft of the motor;

[0024] The centrifugal pump body is provided with a raw material inlet and a product liquid outlet; the centrifugal pump body comprises a pump casing and an impeller, the raw material inlet is located at the center of the pump casing on the side opposite to the impeller axis; the product liquid outlet is located on the side wall of the pump casing;

[0025] The raw material inlet is connected to the raw material input pipe, and the raw material input pipe is a casing, and the casing includes an inner layer pipe and an outer layer pipe; the inner layer pipe is used to pass a rare earth salt solution or a precipitant solution, and the outer layer pipe is used to pass a rare earth salt solution or a precipitant solution, and the solutions passed into the inner layer pipe and the outer layer pipe are different;

[0026] One end of the inner layer pipeline extends out from the outer layer pipeline, and the extended part is communicated with the branch pipeline, and the branch pipeline is used for introducing compressed gas.

[0027] The present invention provides a method for preparing ultrafine rare earth oxide powder, comprising the following steps: providing a precipitation reaction device; the precipitation reaction device is a centrifugal device, the centrifugal device comprising a centrifugal pump body, the centrifugal pump body being provided with a raw material inlet and a product liquid outlet; introducing a rare earth salt solution, a precipitant solution and a compressed gas into the centrifugal device from the raw material inlet for a precipitation reaction to obtain a rare earth precipitate; calcining the rare earth precipitate to obtain ultrafine rare earth oxide powder; and the D of the ultrafine rare earth oxide powder is calcined. 50 The particle size is ≤3μm. The present invention performs a continuous precipitation reaction in a centrifugal device. The rare earth salt solution and the precipitant solution pass through the centrifugal device quickly, which can reduce the contact time and the crystal growth time, thereby maintaining a small particle state. At the same time, the present invention also introduces compressed gas into the centrifugal device, which can greatly increase the degree of chaos in the precipitation reaction, which is conducive to the formation of crystal nuclei in the precipitate and makes the precipitate less likely to age and grow. In addition, the solubility product of the rare earth salt and the precipitant in the precipitation reaction is very small, generally around 10 -20 to 10 -30 The reaction is very rapid, and the two raw materials fully react in the centrifugal state, which can further increase the reaction speed, thereby reducing the crystal growth time while ensuring that the reaction is fully carried out. In addition, the preparation method provided by the present invention is a continuous reaction, which can improve production efficiency and output and reduce production costs.

[0028] Furthermore, the rare earth salts and precipitants used in the present invention are conventional raw materials in the rare earth industry, with wide sources and low costs.

[0029] Furthermore, the present invention can also adjust the particle size of ultrafine rare earth oxides by controlling the flow rates of the rare earth salt solution and the precipitant solution.

[0030] The present invention also provides a device used in the preparation method of the above scheme. The precipitation reaction device used in the present invention has a simple structure, small device investment, high production efficiency and output, and low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is a top view of a precipitation reaction apparatus of the present invention;

[0032] FIG2 is a cross-sectional view taken along line A-A of FIG1;

[0033] In Figures 1 and 2: 1-motor, 2-water cooling system, 3-pump casing, 4-impeller, 5-outer pipeline, 6-inner pipeline, 7-first liquid inlet, 8-second liquid inlet, 9-gas inlet, 10-product liquid outlet;

[0034] FIG3 is a particle size distribution diagram of the ultrafine yttrium oxide powder prepared in Example 1;

[0035] FIG4 is a SEM image of the ultrafine yttrium oxide powder prepared in Example 1;

[0036] FIG5 is a particle size distribution diagram of the ultrafine yttrium oxide powder prepared in Example 2;

[0037] FIG6 is a SEM image of the ultrafine yttrium oxide powder prepared in Example 2;

[0038] FIG7 is a particle size distribution diagram of the ultrafine erbium oxide powder prepared in Example 3;

[0039] FIG8 is a SEM image of the ultrafine erbium oxide powder prepared in Example 3;

[0040] FIG9 is a particle size distribution diagram of the ultrafine lutetium oxide powder prepared in Example 4;

[0041] FIG10 is a SEM image of the ultrafine lutetium oxide powder prepared in Example 4;

[0042] FIG11 is a particle size distribution diagram of yttrium oxide powder prepared in Comparative Example 1;

[0043] FIG12 is a SEM image of yttrium oxide powder prepared in Comparative Example 1;

[0044] FIG13 is a particle size distribution diagram of yttrium oxide powder prepared in Comparative Example 2;

[0045] FIG14 is a SEM image of yttrium oxide powder prepared in Comparative Example 2;

[0046] FIG15 is a particle size distribution diagram of the erbium oxide powder prepared in Comparative Example 3;

[0047] FIG16 is a SEM image of erbium oxide powder prepared in Comparative Example 3;

[0048] FIG17 is a particle size distribution diagram of lutetium oxide powder prepared in Comparative Example 4;

[0049] FIG18 is a SEM image of lutetium oxide powder prepared in Comparative Example 4;

[0050] FIG19 is a particle size distribution diagram of yttrium oxide powder prepared in Comparative Example 5;

[0051] Figure 20 is a SEM image of the yttrium oxide powder prepared in Comparative Example 5. DETAILED DESCRIPTION

[0052] The present invention provides a method for preparing ultrafine rare earth oxide powder, comprising the following steps:

[0053] A precipitation reaction device is provided; the precipitation reaction device is a centrifugal device, the centrifugal device includes a centrifugal pump body, and the centrifugal pump body is provided with a raw material inlet and a product liquid outlet;

[0054] Passing a rare earth salt solution, a precipitant solution and compressed gas into a centrifugal device from a raw material inlet to carry out a precipitation reaction to obtain a rare earth precipitate;

[0055] The rare earth precipitate is calcined to obtain ultrafine rare earth oxide powder; the ultrafine rare earth oxide powder has a D 50 Particle size ≤3μm.

[0056] First, the precipitation reaction device of the present invention will be described. FIG1 is a top view of the precipitation reaction device of the present invention, and FIG2 is a cross-sectional view taken along the A-A plane of FIG1.

[0057] The precipitation reaction device provided by the present invention is a centrifugal device, which includes a centrifugal pump body, which is provided with a raw material inlet and a product liquid outlet; the centrifugal pump body includes a pump casing and an impeller, and the raw material inlet of the centrifugal pump body is located at the center of the pump casing on the side opposite to the impeller axis; the product liquid outlet of the centrifugal pump body is located on the side wall of the pump casing; the position of the product liquid outlet of the centrifugal pump body is preferably higher than the raw material inlet.

[0058] In the present invention, the raw material inlet is connected to a raw material input pipe, which is a casing pipe comprising an inner pipe and an outer pipe. The inner pipe is used to pass a rare earth salt solution or a precipitant solution, while the outer pipe is used to pass a rare earth salt solution or a precipitant solution, and the inner and outer pipes pass different solutions. One end of the inner pipe extends from the outer pipe, and the extended portion is connected to a branch pipe, which is used to pass compressed gas.

[0059] In the present invention, the inlet of the inner layer pipeline is recorded as the first liquid inlet; a liquid inlet is provided on the side wall of the outer layer pipeline, which is recorded as the second liquid inlet; the inlet on the branch pipeline is recorded as the gas inlet; in a specific embodiment of the present invention, liquid flow meters are preferably provided on the pipelines of the first liquid inlet and the second liquid inlet respectively; and a gas flow meter is preferably provided on the pipeline of the gas inlet.

[0060] The present invention has no 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 rate of the rare earth salt solution and the precipitant solution and the capacity of the centrifugal pump body.

[0061] In the present invention, the centrifugal device further includes a motor and a cooling system. The motor's drive shaft is connected to the centrifugal pump body, specifically, is securely connected to the impeller of the centrifugal pump body. When the motor is started, power is transmitted to the impeller via the drive shaft. The cooling system is disposed outside the motor's drive shaft. The present invention has no particular requirements for the structure of the motor and cooling system; those known in the art may be employed.

[0062] The preparation method of the present invention is described below.

[0063] A rare earth salt solution, a precipitant solution, and compressed gas are introduced into a centrifugal device through a raw material inlet for a precipitation reaction to obtain a rare earth precipitate. In the present invention, the rare earth salt in the rare earth salt solution preferably includes one or more of rare earth chloride and rare earth nitrate. The present invention has no particular requirements for the rare earth element in the rare earth salt; any rare earth element can 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.

[0064] 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; 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.

[0065] In the present invention, the precipitant in the precipitant solution preferably includes one or more of oxalic acid, ammonium bicarbonate, sodium hydroxide and ammonia water; the concentration of the precipitant solution is preferably 10 to 100 g / L, more preferably 20 to 80 g / L; 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.

[0066] In the present invention, the compressed gas is introduced from the gas inlet; the rare earth salt solution and the precipitant solution are preferably introduced from the first liquid inlet or the second liquid inlet, respectively, or from the second liquid inlet and the first liquid inlet, respectively; that is, the present invention has no requirements on the specific inlets for the rare earth salt solution and the precipitant solution, and the first liquid inlet and the second liquid inlet can be arbitrarily selected, as long as they are introduced into the centrifugal device simultaneously from different liquid inlets.

[0067] In the present invention, the flow ratio of the rare earth salt solution to the precipitant solution is preferably 1:(1-1.2), more preferably 1:(1-1.1).

[0068] 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 rate of the rare earth solution and the precipitant solution; specifically, the greater the flow rate of the rare earth solution and the precipitant solution, the smaller the particle size of the obtained ultrafine rare earth oxide powder.

[0069] In the present invention, the compressed gas is preferably one or more of compressed air, compressed nitrogen, compressed carbon dioxide, and compressed oxygen; the pressure of the compressed gas is 0.1 to 0.8 MPa, preferably 0.2 to 0.5 MPa. The present invention controls the pressure of the compressed gas within the above range to ensure that the compressed gas is introduced into the centrifugal device. The present invention introduces compressed gas into the centrifugal device. Under the high-speed rotation of the centrifugal device, the liquid and gas rotate around the inner wall of the centrifugal pump, and bubbles are mixed in the liquid, increasing the gas-liquid interface of the reaction. At the same time, the bubbles continuously burst, which can increase the intensity of the reaction stirring, facilitate the formation of crystal nuclei in the precipitate, and prevent the precipitate from aging and growing.

[0070] In the present invention, during the precipitation reaction, the centrifugal speed of the centrifugal device (ie, the speed of the motor) is preferably 1000 to 3000 rpm, more preferably 2000 to 3000 rpm.

[0071] In the present invention, the precipitation reaction can be carried out at room temperature.

[0072] In a specific embodiment of the present invention, the motor power supply is preferably first activated, and then the rare earth salt solution, precipitant solution, and compressed gas are simultaneously introduced into the centrifugal device for reaction, and the product liquid is collected from the product liquid outlet. After obtaining the product liquid, the present invention preferably separates and washes the solid product therein to obtain a rare earth precipitate; depending on the precipitant used, the rare earth precipitate is preferably one or more of rare earth oxalate, rare earth carbonate, and rare earth hydroxide.

[0073] 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 temperature is preferably 800-1000° C., and the calcination time is preferably 2-8 hours.

[0074] In the present invention, the D of the ultrafine rare earth oxide powder is 50 The particle size is ≤3 μm, preferably 0.5 to 3 μm.

[0075] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0076] The structures of the precipitation reaction devices used in the following examples are shown in FIG1 and FIG2 , wherein the capacity of the centrifugal pump body is 2 L.

[0077] Example 1

[0078] Ultrafine yttrium oxide powder was prepared using a precipitation reaction device: after turning on the power of the device, yttrium chloride solution and oxalic acid solution were introduced into the centrifugal pump from the first liquid inlet and the second liquid inlet respectively, wherein the concentration of yttrium chloride solution was 0.2 mol / L and the flow rate was 1m 3 / h, the concentration of oxalic acid solution is 45g / L, and the flow rate is 1.05m 3 / h, the reaction temperature is room temperature; at the same time, compressed air is introduced into the centrifugal pump from the gas inlet, the compressed air pressure is 0.2MPa, and the motor speed is 1500rpm. The product liquid is received from the outlet of the centrifugal pump; the solid product in the product liquid is separated and washed to obtain yttrium oxalate, and the obtained yttrium oxalate is calcined at 950℃ for 4h to obtain ultrafine yttrium oxide powder, D 50 The particle size is 0.86μm.

[0079] FIG3 is a particle size distribution diagram of the ultrafine yttrium oxide powder obtained in Example 1, Table 1 is a particle size distribution table, and FIG4 is a SEM image of the ultrafine yttrium oxide powder obtained in Example 1.

[0080] Table 1 Particle size distribution of ultrafine yttrium oxide powder obtained in Example 1

[0081] According to Figures 3 and 4 and Table 1, it can be seen that the ultrafine yttrium oxide powder prepared in Example 1 has a uniform and fine particle size.

[0082] Example 2

[0083] Ultrafine yttrium oxide powder was prepared using a precipitation reaction device: after turning on the power of the device, yttrium chloride solution and ammonium bicarbonate solution were introduced into the centrifugal pump from the first liquid inlet and the second liquid inlet respectively. The concentration of yttrium chloride solution was 0.16 mol / L and the flow rate was 2.7 m 3 / h, the concentration of ammonium bicarbonate solution is 20g / L, and the flow rate is 2.8m 3 / h, the reaction temperature is room temperature; at the same time, compressed air is introduced into the centrifugal pump from the gas inlet, the compressed air pressure is 0.3MPa, and the motor speed is 1000rpm. The product liquid is received from the outlet of the centrifugal pump; the solid product in the product liquid is separated and washed to obtain yttrium carbonate, which is calcined at 850℃ for 6h to obtain ultrafine yttrium oxide powder, D 50 The particle size is 0.77μm.

[0084] Figure 5 is a particle size distribution diagram of the ultrafine yttrium oxide powder obtained in Example 2, Table 2 is a particle size distribution table, and Figure 6 is a SEM image of the ultrafine yttrium oxide powder obtained in Example 2.

[0085] Table 2 Particle size distribution of ultrafine yttrium oxide powder obtained in Example 2

[0086] According to Figures 5 to 6 and Table 2, it can be seen that the ultrafine yttrium oxide powder prepared in Example 2 has a uniform and fine particle size.

[0087] Example 3

[0088] Ultrafine erbium oxide was prepared by using a precipitation reaction device: after turning on the power of the device, erbium chloride solution and oxalic acid solution were introduced into the centrifugal pump from the first liquid inlet and the second liquid inlet respectively, wherein the concentration of erbium chloride solution was 0.25 mol / L and the flow rate was 2m 3 / h, the concentration of oxalic acid solution is 50g / L, the flow rate is 2m 3 / h, the reaction temperature is room temperature; at the same time, compressed nitrogen is introduced into the centrifugal pump from the gas inlet, the compressed nitrogen pressure is 0.1MPa, and the motor speed is 2000rpm. The product liquid is received from the outlet of the centrifugal pump; the solid product in the product liquid is separated and washed to obtain erbium oxalate, which is calcined at 900℃ for 4h to obtain ultrafine erbium oxide powder, D 50 The particle size was 0.69 μm. The clear solution obtained by filtering the product solution was added dropwise to oxalic acid. No precipitate was generated, indicating that the precipitation reaction was relatively complete.

[0089] FIG7 is a particle size distribution diagram of the ultrafine erbium oxide powder obtained in Example 3, Table 3 is a particle size distribution table, and FIG8 is a SEM image of the ultrafine erbium oxide powder obtained in Example 3.

[0090] Table 3 Particle size distribution of ultrafine erbium oxide powder obtained in Example 3

[0091] According to Figures 7 to 8 and Table 3, it can be seen that the ultrafine erbium oxide powder prepared in Example 3 has a uniform and fine particle size.

[0092] Example 4

[0093] Ultrafine lutetium oxide was prepared using a precipitation reaction device: after turning on the device power, lutetium nitrate solution and oxalic acid solution were introduced into the centrifugal pump from the first liquid inlet and the second liquid inlet respectively. The concentration of lutetium nitrate solution was 0.3 mol / L and the flow rate was 0.5 m 3 / h, the concentration of oxalic acid solution is 60g / L, and the flow rate is 0.55m 3 / h, the reaction temperature is room temperature; at the same time, compressed air is introduced into the centrifugal pump from the gas inlet, the compressed air pressure is 0.25MPa, and the motor speed is 2200rpm. The product liquid is received from the outlet of the centrifugal pump; the solid product in the product liquid is separated and washed to obtain lutetium oxalate, and the obtained lutetium oxalate is calcined at 950℃ for 3h to obtain ultrafine lutetium oxide powder, D 50 The particle size is 0.82μm.

[0094] FIG9 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 FIG10 is a SEM image of the ultrafine lutetium oxide powder obtained in Example 4.

[0095] Table 4 Particle size distribution of ultrafine lutetium oxide powder obtained in Example 4

[0096] According to Figures 9 to 10 and Table 4, it can be seen that the ultrafine lutetium oxide powder prepared in Example 4 has a uniform and fine particle size.

[0097] Comparative Example 1

[0098] Yttrium chloride solution and oxalic acid solution were co-precipitated in a reactor. Both yttrium chloride solution and oxalic acid solution were added into the reactor under the control of flow meter. The concentration of yttrium chloride solution was 0.2 mol / L and the flow rate was 1m 3 / h; the concentration of oxalic acid solution is 45g / L, and the flow rate is 1.05m 3 / h; stirring speed is 120rpm, reaction time is 1h (reaction time is measured from the start of adding materials), and reaction temperature is room temperature. The solid product in the obtained product liquid is separated and washed to obtain yttrium oxalate, and the obtained yttrium oxalate is calcined at 950℃ for 4h to obtain yttrium oxide powder, D 50 The particle size is 5.37μm.

[0099] Figure 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 Figure 12 is a SEM image of the yttrium oxide powder obtained in Comparative Example 1.

[0100] Table 5 Particle size distribution of yttrium oxide powder obtained in Comparative Example 1

[0101] According to the data in Figures 11 and 12 and Table 5, the particle size of the yttrium oxide powder prepared in Comparative Example 1 is relatively large and does not meet the requirements of ultrafine rare earth oxide powder.

[0102] Comparative Example 2

[0103] Yttrium chloride solution and ammonium bicarbonate solution were co-precipitated in a reactor. Both yttrium chloride solution and ammonium bicarbonate solution were added to the reactor under the control of a flow meter. The concentration of yttrium chloride solution was 0.16 mol / L and the flow rate was 2.7 m 3 / h; the concentration of ammonium bicarbonate solution is 20g / L, and the flow rate is 2.8m 3 / h; stirring speed is 120rpm, reaction time is 2h (reaction time is measured from the start of adding materials), and reaction temperature is room temperature. The solid product in the obtained product liquid is separated and washed to obtain yttrium carbonate, which is calcined at 850℃ for 6h to obtain yttrium oxide powder, D 50 The particle size is 5.50μm.

[0104] Figure 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 Figure 14 is a SEM image of the yttrium oxide powder obtained in Comparative Example 2.

[0105] Table 6 Particle size distribution of yttrium oxide powder obtained in Comparative Example 2

[0106] According to the data in Figures 13 and 14 and Table 6, the particle size of the yttrium oxide powder prepared in Comparative Example 2 is relatively large and does not meet the requirements of ultrafine rare earth oxide powder.

[0107] Comparative Example 3

[0108] The erbium chloride solution and the oxalic acid solution were co-precipitated in the reactor. The erbium chloride solution and the oxalic acid solution were added to the reactor under the control of the flow meter. The concentration of the erbium chloride solution was 0.25 mol / L and the flow rate was 2 m 3 / h; the concentration of oxalic acid solution is 50g / L, and the flow rate is 2m 3 / h; stirring speed is 120rpm, reaction time is 0.5h (reaction time is measured from the start of adding materials), and reaction temperature is room temperature. The solid product in the obtained product liquid is separated and washed to obtain erbium oxalate, which is calcined at 900℃ for 4h to obtain erbium oxide powder, D 50 The particle size is 8.32μm.

[0109] Figure 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 Figure 16 is a SEM image of the erbium oxide powder obtained in Comparative Example 3.

[0110] Table 7 Particle size distribution of erbium oxide powder obtained in Comparative Example 3

[0111] According to the data in FIG. 15 to FIG. 16 and Table 7, the particle size of the erbium oxide powder prepared in Comparative Example 3 is relatively large and does not meet the requirements of ultrafine rare earth oxide powder.

[0112] Comparative Example 4

[0113] Lutetium nitrate solution and oxalic acid solution were co-precipitated in a reactor. Lutetium nitrate solution and oxalic acid solution were added to the reactor under the control of a flow meter. The concentration of lutetium nitrate solution was 0.3 mol / L and the flow rate was 0.5 m 3 / h; the concentration of oxalic acid solution is 60g / L, and the flow rate is 0.55m 3 / h; stirring speed is 120rpm, reaction time is 3h (reaction time is measured from the start of adding materials), and reaction temperature is room temperature. The solid product in the obtained product liquid is separated and washed to obtain lutetium oxalate, which is calcined at 950℃ for 3h to obtain lutetium oxide powder. 50 The particle size is 7.31μm.

[0114] Figure 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 Figure 18 is a SEM image of the lutetium oxide powder obtained in Comparative Example 4.

[0115] Table 8 Particle size distribution of lutetium oxide powder obtained in Comparative Example 4

[0116] According to the data in Figures 17 and 18 and Table 8, the particle size of the lutetium oxide powder prepared in Comparative Example 4 is relatively large and does not meet the requirements of ultrafine rare earth oxide powder.

[0117] Comparative Example 5

[0118] The other conditions were the same as those in Example 1, except that the introduction of compressed gas was omitted. 50 The particle size is 3.97μm.

[0119] Figure 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 Figure 20 is a SEM image of the yttrium oxide powder obtained in Comparative Example 5.

[0120] Table 9 Particle size distribution of yttrium oxide powder obtained in Comparative Example 5

[0121] According to the data in Figures 19 to 20 and Table 9, after omitting the introduction of compressed gas, the particle size of the obtained yttrium oxide powder is larger, indicating that the introduction of compressed air can increase the degree of chaos in the reaction, which is conducive to the formation of crystal nuclei in the precipitate and makes it less likely for the precipitate to age and grow.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-fine rare earth oxide powder, characterized in that, It includes the following steps: Carry out a precipitation reaction on the rare earth salt solution, precipitant solution and compressed gas under centrifugal conditions to obtain rare earth precipitates; Calcine the rare earth precipitate to obtain an ultrafine rare earth oxide powder; the D 50 particle size of the ultrafine rare earth oxide powder is ≤ 3 μm.

2. The preparation method according to claim 1, characterized in that, It includes the following steps: Provide a precipitation reaction device; the precipitation reaction device is a centrifugal device, the centrifugal device includes a centrifugal pump body, and the centrifugal pump body is provided with a raw material inlet and a product liquid outlet; Introduce the rare earth salt solution, precipitant solution and compressed gas into the centrifugal device through the raw material inlet to carry out a precipitation reaction to obtain rare earth precipitates; Calcine the rare earth precipitate to obtain an ultrafine rare earth oxide powder; the D 50 particle size of the ultrafine rare earth oxide powder is ≤ 3 μm.

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

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

5. The preparation method according to claim 2, characterized in that, The precipitant in the precipitant solution includes one or more of oxalic acid, ammonium bicarbonate, sodium hydroxide, and ammonia water; the concentration of the precipitant solution is 10 to 100 g / L; the flow rate of the precipitant solution is 0.2 to 3 m 3 / h.

6. The preparation method according to claim 3 or 5, characterized in that The flow rate ratio of the rare earth salt solution to the precipitant solution is 1:(1 - 1.2).

7. The preparation method according to claim 2, characterized in that, The compressed gas is one or more of compressed air, compressed nitrogen, compressed carbon dioxide and compressed oxygen; the pressure of the compressed gas is 0.1 - 0.8 MPa.

8. The preparation method according to claim 2, characterized in that, In the precipitation reaction, the centrifugal speed of the centrifugal device is 1000 - 3000 rpm.

9. The preparation method according to claim 2, wherein The centrifugal pump body includes a pump casing and an impeller. The raw material inlet of the centrifugal pump body is located at the center of the pump casing on the side opposite to the axis of the impeller; the product liquid outlet of the centrifugal pump body is located on the side wall of the pump casing.

10. The preparation method according to claim 2 or 9, characterized in that, The raw material inlet is communicated with a raw material input pipe. The raw material input pipe is a sleeve, and the sleeve includes an inner pipeline and an outer pipeline; the inner pipeline is used to introduce the rare earth salt solution or the precipitant solution, and the outer pipeline is used to introduce the rare earth salt solution or the precipitant solution, and the solutions introduced into the inner pipeline and the outer pipeline are different; One end of the inner pipeline extends out of the outer pipeline, and the extended part is communicated with a branch pipeline, and the branch pipeline is used to introduce compressed gas.

11. The preparation method according to claim 2, characterized in that, The centrifugal device further includes a motor and a cooling system; the drive shaft of the motor is connected to the centrifugal pump body; the cooling system is arranged outside the drive shaft of the motor.

12. The preparation method according to claim 1, characterized in that, The temperature of the calcination is 800 - 1000 °C, and the time is 2 - 8 h.

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

14. The device used in the preparation method according to any one of claims 1 to 13, characterized in that, The device is a precipitation reaction device, and the precipitation reaction device is a centrifugal device; the centrifugal device includes a motor, a centrifugal pump body and a cooling system; the drive shaft of the motor is connected to the centrifugal pump body; the cooling system is arranged outside the drive shaft of the motor; The centrifugal pump body is provided with a raw material inlet and a product liquid outlet; the centrifugal pump body includes a pump casing and an impeller. The raw material inlet is located at the center of the pump casing on the side opposite to the axis of the impeller; the product liquid outlet is located on the side wall of the pump casing; The raw material inlet is communicated with a raw material input pipe. The raw material input pipe is a sleeve, and the sleeve includes an inner pipeline and an outer pipeline; the inner pipeline is used to introduce the rare earth salt solution or the precipitant solution, and the outer pipeline is used to introduce the rare earth salt solution or the precipitant solution, and the solutions introduced into the inner pipeline and the outer pipeline are different; One end of the inner pipeline extends out of the outer pipeline, and the extended part is communicated with a branch pipeline, and the branch pipeline is used to introduce compressed gas.

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