Methods for increasing the phase transition rate and use of carboxylic acid group-containing substances

Abstract

To provide a method for increasing a phase transition rate that can significantly increase the phase transition rate from rare earth carbonate to basic rare earth carbonate and reduce the content of impurities such as Cl-, SO42-, and NO3-.SOLUTION: A method for increasing a phase transition rate in a process of preparing basic rare earth carbonate from rare earth carbonate comprises the steps of mixing rare earth carbonate and an aqueous solution of a carboxylic acid group-containing substance to obtain a slurry and heating the slurry for reaction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for increasing the phase transition rate in the process of preparing basic rare carbonate from rare carbonate, a method for preparing basic rare carbonate from rare carbonate, and the use of a carboxylic acid group-containing substance. [Background technology]

[0002] Due to their unique properties in terms of light, heat, electricity, magnetism, wear resistance, corrosion resistance, and antibacterial properties, rare earth elements are seeing an expansion of applications and have earned the titles of "industrial gold" and "industrial vitamins." Quality requirements for rare earth-related products (e.g., rare earth oxides, rare earth fluorides) regarding purity, particle size, crystal type, and type are becoming increasingly stringent, especially in high-end application fields.

[0003] Rare earth carbonates and basic rare earth carbonates are precursor compounds for forming rare earth-related products such as rare earth oxides and rare earth fluorides. Rare earth carbonates and basic rare earth carbonates are obtained by precipitating rare earth solutions (e.g., rare earth chloride solutions, rare earth nitrate solutions, or rare earth sulfate solutions). However, usually, (1) in the process of precipitating rare earth carbonates or basic rare earth carbonates from rare earth solutions, for example, Cl - SO4 2- NO3 - In rare earth solution systems such as the above, acid anions remain in the rare earth carbonate or basic rare earth carbonate in various forms, becoming impurities in the functional material at the end, which adversely affects the performance of these materials. (2) In the process of precipitating rare earth solutions using conventional equipment, it is difficult to control the particle size of rare earth carbonate or basic rare earth carbonate, making it difficult to obtain rare earth compounds with particle sizes of 5 μm or less.

[0004] CN104310456A discloses a method for producing rare earth carbonates. By supplying rare earth chloride and a carbonate solution in parallel to a specific precipitation reactor and controlling the supply rate and discharge rate, the maturation time of the rare earth carbonates is controlled, spatial separation of the reaction zone and the crystallization zone is achieved, and a fine-grained, low-chlorine rare earth carbonate product is directly precipitated from a hydrochloric acid medium. In this method, although the obtained rare earth carbonates have a chlorine group content of less than 50 ppm and small particle size, special equipment is required.

[0005] CN115849429A discloses a method for preparing lanthanum carbonate tetrahydrate. A mixed solution of hydrochloric acid and lanthanum chloride is prepared by reacting excess hydrochloric acid with lanthanum oxide, then this mixed solution is transferred to a sealed reaction vessel, sodium bicarbonate solution is gradually added to the sealed reaction vessel, the emission of carbon dioxide generated in the neutralization reaction is controlled, and the reaction is carried out in a carbon dioxide-rich positive pressure environment while maintaining a positive pressure of 100 to 1000 Pa inside the sealed reaction vessel, and after the reaction is complete, the mixture is filtered and washed with water to obtain wet lanthanum carbonate octahydrate, and the wet lanthanum carbonate octahydrate is dried to obtain lanthanum carbonate tetrahydrate, which has a high chloride ion content, D 50 They are 6-10 μm in size, which is somewhat large.

[0006] Acid anions obtained during the precipitation process of rare earth solutions (e.g., Cl - SO4 2- NO3 - For rare earth carbonates containing high concentrations (e.g., 100 ppm or more) of substances such as , and with large particle sizes, how to process them to reduce the acid anion content and enable smaller particle sizes is an urgent technical challenge that needs to be addressed.

[0007] Document CN103708525A discloses a method for producing low-chlorine rare earth carbonates and oxides. Rare earth carbonates are placed in an alkaline hot aqueous solution with a pH of 7 or higher and a temperature of 80°C or higher, and reacted for 30 minutes or more with a liquid-to-solid ratio of 1:1 to 50:1 and a molar ratio of alkali to rare earth of 0.5:1 to 1.1:1. The basic rare earth carbonates obtained by this production method still have large particle sizes and a high chlorine group content.

Summary of the Invention

[0008] In view of the above problems, one object of the present invention is to significantly increase the phase transition rate from rare earth carbonate to basic rare earth carbonate and significantly reduce the content of impurities such as Cl - , SO4 2- and NO3 - and provide a method for increasing the phase transition rate. Another object of the present invention is to provide a method for preparing basic rare earth carbonate from rare earth carbonate.

[0009] Another object of the present invention is to provide the use of carboxylic acid group-containing substances.

[0010] The present invention achieves the above object with the following constitution.

[0011] In one aspect, the present invention provides a method for increasing the phase transition rate in the process of preparing basic rare earth carbonate from rare earth carbonate, including the steps of mixing rare earth carbonate with an aqueous solution of a carboxylic acid group-containing substance to obtain a slurry, and heating and reacting the slurry.

[0012] In another aspect, the present invention further provides a method for preparing basic rare earth carbonate from rare earth carbonate, including the steps of mixing rare earth carbonate with an aqueous solution of a carboxylic acid group-containing substance to obtain a slurry, heating and reacting the slurry to obtain an intermediate product, and converting the intermediate product into basic rare earth carbonate crystals, basic rare earth carbonate clusters, or a mixture of basic rare earth carbonate crystals and basic rare earth carbonate clusters.

[0013] According to the method of the present invention, preferably, the carboxylic acid group-containing substance is (1) a C1-C6 monovalent carboxylic acid, or (2) A mixture of a C1-C6 monovalent carboxylic acid and a C1-C6 monovalent ammonium carboxylic acid salt. It was selected from among them.

[0014] According to the method of the present invention, preferably, The C1-C6 monovalent carboxylic acid is one or more selected from formic acid, acetic acid, and propionic acid. The mixture of a C1-C6 monovalent carboxylic acid and a C1-C6 monovalent ammonium carboxylic acid salt is selected from a mixture of formic acid and ammonium formate, a mixture of acetic acid and ammonium acetate, or a mixture of propionic acid and ammonium propionate.

[0015] According to the method of the present invention, preferably, The amount of the carboxylic acid group-containing substance used is 1 to 9% of the theoretical number of moles required for the complex formation reaction between the carboxylic acid group-containing substance and the rare earth element in the rare earth carbonate. The concentration of the carboxylic acid group-containing substance in the aqueous solution of the aforementioned carboxylic acid group-containing substance is 0.015 to 0.15 mol / L.

[0016] According to the method of the present invention, preferably, the slurry is heated to 50 to 100°C and reacted for 10 to 600 minutes.

[0017] According to the method of the present invention, preferably, The process includes converting the intermediate product into basic rare earth carbonate crystals, basic rare earth carbonate clusters, or a mixture of basic rare earth carbonate crystals and basic rare earth carbonate clusters, followed by solid-liquid separation, and then circulating the resulting filtrate as an aqueous solution of a carboxylic acid group-containing substance.

[0018] According to the method of the present invention, preferably, Cl in rare earth carbonates - SO4 2- and NO3 - The total content exceeds 120 ppm, and Cl in basic carbonate rare earth - SO4 2- and NO3- The total content is 50 ppm or less than 50 ppm. Average particle size D of basic rare earth carbonates 50 It is less than 5.5 μm.

[0019] In another embodiment, the present invention provides the use of a carboxylic acid group-containing substance used to increase the phase transition rate in the process of preparing basic rare earth carbonates from rare earth carbonates.

[0020] According to the use of the present invention, preferably, the carboxylic acid group-containing substance is (1) C1-C6 monovalent carboxylic acids, or (2) A mixture of a C1-C6 monovalent carboxylic acid and a C1-C6 monovalent ammonium carboxylic acid salt. It was selected from among them.

[0021] The method according to the present invention can increase the phase transition rate when preparing basic rare earth carbonates from rare earth carbonates. Furthermore, the present invention allows for the use of acid anions (e.g., Cl - SO4 2- and NO3 - It is possible to convert rare earth carbonates containing high amounts of (etc.) and with large particle sizes into basic rare earth carbonates containing low amounts of acid anions and with small particle sizes. The total acid anion content can be reduced from 200 ppm or more to 50 ppm or less. The carboxylic acid group-containing substance according to the present invention is used in small quantities, can be recycled, is low-cost, and is environmentally friendly. Compared to traditional hydrothermal conversion methods, which have high energy consumption, the method according to the present invention has the advantages of high speed, low energy consumption, a simple process, and ease of industrial production. Furthermore, the method according to the present invention allows for process control and can convert into basic rare earth carbonate crystals, basic rare earth carbonate clusters, or a mixture of basic rare earth carbonate crystals and basic rare earth carbonate clusters. [Brief explanation of the drawing]

[0022] [Figure 1] This is an SEM image of the basic lanthanum carbonate obtained in Example 1 of the present invention. [Figure 2] This is an XRD diagram of basic lanthanum carbonate obtained in Example 1 of the present invention. [Figure 3] This is an XRD diagram of basic cerium carbonate obtained in Example 2 of the present invention. [Figure 4] This is an XRD diagram of cerium carbonate octahydrate used as a raw material in Example 2 of the present invention. [Figure 5] This is an SEM image of basic praseodymium neodymium carbonate obtained in Example 3 of the present invention. [Figure 6] This is an XRD diagram of basic europium carbonate obtained in Example 6 of the present invention. [Figure 7] This is an SEM image of basic europium carbonate obtained in Example 6 of the present invention. [Figure 8] This is an SEM image of the product obtained using a ratio of 1. [Figure 9] This is an XRD diagram of the intermediate product and product in a proportional relationship of 1. [Figure 10] This is an SEM image of the product obtained using a proportional ratio of 2. [Figure 11] This is an XRD diagram of the intermediate product and product in the proportionality 2 model. [Modes for carrying out the invention]

[0023] The present invention will be further described below with reference to specific examples, but the scope of protection of the present invention is not limited to these.

[0024] In this invention, Cm~Cn indicates having m~n carbon atoms, and for example, C1~C6 monovalent carboxylic acid refers to a monovalent carboxylic acid having 1~6 carbon atoms.

[0025] "D" in the present invention 50" is the median diameter or median particle size, and indicates the particle size corresponding to the point when the cumulative particle size distribution percentage of a given sample reaches 50%. In a physical sense, particles larger than this size account for 50%, and particles smaller than this size also account for 50%.

[0026] The present invention provides a method for increasing the phase transition rate in the process of preparing basic rare carbonate from rare carbonate, comprising (1) a mixing step and (2) a reaction step. Preferably, the method further comprises (3) a conversion step. The present invention provides a method for preparing basic rare carbonate from rare carbonate, comprising (1) a mixing step, (2) a reaction step, and (3) a conversion step. A detailed explanation follows below.

[0027] <Mixing step> A slurry is obtained by mixing rare earth carbonate with an aqueous solution of a carboxylic acid group-containing substance. This is advantageous for increasing the phase transition rate. Furthermore, it is advantageous for reducing the acid anion content and obtaining basic rare earth carbonate with small particle size.

[0028] In the present invention, the rare earth element RE in the rare earth carbonate may be one or more of the elements from La to Gd in ascending order of atomic number. Examples of rare earth elements RE include lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc), and yttrium (Y). Preferably, the rare earth element RE is lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc), and yttrium (Y). Preferably, the rare earth element RE is one or more selected from lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), and gadolinium (Gd). More preferably, the rare earth element RE is one or more selected from lanthanum (La), cerium (Ce), and samarium (Sm). This is advantageous for obtaining basic rare earth carbonate nanocrystals and for reducing the particle size of the basic rare earth carbonate. More preferably, the rare earth element RE is lanthanum (La). This is advantageous for obtaining nano-sized basic rare earth carbonate.

[0029] Cl in rare earth carbonates - SO4 2- and NO3 - The total content of is greater than 120 ppm, preferably greater than 150 ppm, and more preferably greater than 200 ppm. D of rare earth carbonate 50 The particle size is 45 μm or larger. After such rare earth carbonates are treated by the method according to the present invention, the particle size becomes smaller and Cl - SO4 2- and NO3 -This is advantageous for obtaining basic carbonate rare earths in which the total content of is 50 ppm or less.

[0030] In the present invention, rare earth carbonate (i.e., rare earth carbonate) may be a solid powder of rare earth carbonate that does not contain crystal water, or it may be rare earth carbonate that contains crystal water. Many rare earth carbonates contain crystal water.

[0031] In the present invention, the carboxylic acid group-containing substance in the aqueous solution of the carboxylic acid group-containing substance is (1) C1-C6 monovalent carboxylic acids, or (2) A mixture of C1-C6 monovalent carboxylic acids and C1-C6 monovalent ammonium carboxylic acid salts. It was selected from among them.

[0032] In some specific embodiments, the carboxylic acid group-containing substance is selected from C1-C6 monovalent carboxylic acids. In some other specific embodiments, the carboxylic acid group-containing substance is selected from a mixture of C1-C6 monovalent carboxylic acids and their ammonium salts.

[0033] Examples of C1-C6 monovalent carboxylic acids include, but are not limited to, formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, and n-hexanoic acid. In some specific embodiments, the carboxylic acid group-containing substance is one or more selected from formic acid, acetic acid, propionic acid, and n-butyric acid. The carboxylic acid group-containing substance is preferably acetic acid. This is advantageous for obtaining nano-sized basic carbonate rare earths.

[0034] In several other specific embodiments, the carboxylic acid group-containing substance is one or more mixtures selected from a mixture of formic acid and ammonium formate, a mixture of acetic acid and ammonium acetate, a mixture of propionic acid and ammonium propionate, and a mixture of n-butyric acid and ammonium n-butyrate. Preferably, the carboxylic acid group-containing substance is a mixture of acetic acid and ammonium acetate. This is advantageous for obtaining basic rare earth carbonate nanocrystals and for reducing the particle size of the basic rare earth carbonate.

[0035] In the present invention, the molar ratio of a C1-C6 monovalent carboxylic acid to the corresponding ammonium salt is not limited and may be, for example, 10 to 1:1, specifically 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, or 1:1.

[0036] Rare earth carbonates undergo hydrolysis in high-temperature aqueous solutions, RE 3+ The bond between H2O is [RE(OH)(H2O)] n-1 ] 2+ It exists as CO3 2- Ions are [RE(OH)(H2O)] n-1 ] 2+ We have discovered that when it collides with another substance, it reacts to produce RECO3OH.

[0037] When a carboxylic acid group-containing substance is added to the reaction system, the carboxylic acid group-containing substance first reacts with rare earth carbonate, and as the temperature rises, the ionization of the carboxylic acid is promoted, resulting in more H + It releases CO2, accelerating the dissolution of rare earth carbonates, and the reaction releases CO2, and the carbonic acid produced by the dissolution of CO2 into water is CO3 2- and H + Further generation, faster dissolution of rare earth carbonates, and more RE 3+ Ions and CO3 2- It generates CO3 2- Ions are [RE(OH)(H2O)] n-1 ] 2+ When collisions occur, a reaction takes place, producing RECO3OH, which increases the phase transition rate from rare earth carbonate to basic rare earth carbonate.

[0038] Although the principle is not clear, the reaction is thought to be represented by equations (1) to (5).

[0039] In this invention, we have found that by using an aqueous solution of a carboxylic acid group-containing substance, the phase transition rate of rare earth carbonate can be increased, resulting in a 50-200% increase in the phase transition rate compared to a pure aqueous solution under the same conditions. By changing the morphology and particle size levels, impurities present in encapsulated and entrained states, especially Cl, can be increased. - SO4 2- and NO3 - These impurities are released, resulting in an effect of reducing impurities.

[0040] Furthermore, this invention has found that acetic acid can also function as a dispersant, effectively suppressing the aggregation of basic carbonate rare earth elements.

[0041] The aqueous solution of the carboxylic acid group-containing substance according to the present invention has a concentration of 0.015 to 0.15 mol / L, preferably 0.03 to 0.15 mol / L, and more preferably 0.05 to 0.135 mol / L. The amount of carboxylic acid group-containing substance used in the aqueous solution is 1 to 9% of the theoretical number of moles required for the complex formation reaction between the carboxylic acid group-containing substance and the rare earth elements in the rare earth carbonate, preferably 2 to 9%, and more preferably 3 to 8%. In this invention, a slurry is obtained by mixing a rare earth carbonate solid with an aqueous solution of the carboxylic acid group-containing substance. This is advantageous in increasing the phase transition rate, obtaining basic rare earth carbonate with a smaller particle size, and reducing the acid anion content.

[0042] <Reaction Steps and Transformation Steps> The slurry is heated and reacted to obtain an intermediate product. This is advantageous for increasing the phase transition rate. Further heating converts the intermediate product into basic rare-earth carbonate crystals, basic rare-earth carbonate clusters, or a mixture of basic rare-earth carbonate crystals and basic rare-earth carbonate clusters.

[0043] The temperature of the reaction step and the conversion step may be 50 to 100°C, preferably 60 to 95°C, and more preferably 70 to 90°C. The total time of the reaction step and the conversion step may be 10 to 600 min, preferably 20 to 300 min, and more preferably 30 to 200 min. In some embodiments, the time of the reaction step may be 10 to 90 min, preferably 20 to 80 min, and more preferably 30 to 60 min. The time of the conversion step may be 50 to 300 min, preferably 60 to 200 min, and more preferably 70 to 100 min.

[0044] Stirring is necessary during the reaction and transformation steps. The stirring speed is 150 to 1000 rpm, preferably 200 to 800 rpm, more preferably 250 to 700 rpm, and even more preferably 300 to 600 rpm. This is advantageous for increasing the phase transition rate, obtaining basic carbonate rare earth with smaller particle size, and Cl - SO4 2- and NO3 - This is advantageous in reducing the content of impurities such as these.

[0045] The intermediate product is converted into basic rare earth carbonate crystals, basic rare earth carbonate clusters, or a mixture of basic rare earth carbonate crystals and basic rare earth carbonate clusters. After solid-liquid separation, the resulting filtrate is recycled as an aqueous solution of a carboxylic acid group-containing substance. This allows for the acquisition of basic rare earth carbonate, the recycling of the resulting filtrate, and a reduction in wastewater generation.

[0046] Solid-liquid separation may be performed by centrifugation or filtration, preferably by filtration. Filtration yields a filtration cake and filtrate. The filtrate is recycled as an aqueous solution of a carboxylic acid group-containing substance, and additional carboxylic acid group-containing substances can be added as needed. The separated solid is washed with water, and the washed solid is dried to obtain a basic rare-earth carbonate product. The basic rare-earth carbonate product may be basic rare-earth carbonate crystals, basic rare-earth carbonate clusters, or a mixture of basic rare-earth carbonate crystals and basic rare-earth carbonate clusters.

[0047] Cl in basic rare earth carbonates prepared by the method according to the present invention - SO4 2- and NO3 - The total content is 50 ppm or less than 50 ppm, and the average particle size D 50 The average particle size is less than 5.5 μm. 50 The particle size is less than 5.5 μm, preferably 5 μm or less than 5 μm.

[0048] According to one embodiment of the present invention, a method for preparing basic rare earth carbonates from rare earth carbonates is: Cl - SO4 2- and NO3 - The total content exceeds 200 ppm, and the average particle size D 50 A step of providing rare earth carbonate having a particle size of 45 μm or more, The method includes the step of preparing an aqueous solution of a carboxylic acid group-containing substance having a molar concentration of 0.015 to 0.15 mol / L.

[0049] The rare earth carbonate is added to an aqueous solution of a carboxylic acid group-containing substance and mixed (the amount of carboxylic acid group-containing substance used is 1-9% of the theoretical number of moles required for the complex formation reaction between the carboxylic acid group-containing substance and the rare earth elements in the rare earth carbonate) to obtain a slurry. The slurry is heated to 70-100°C and reacted for 10-90 minutes at a stirring speed of 150-500 rpm and a temperature of 70-100°C to obtain an intermediate product. The intermediate product is then converted for 50-300 minutes at a stirring speed of 150-500 rpm and a temperature of 70-100°C. The mixture is filtered to obtain a filter cake and filtrate, the filtrate is stored for reuse, the filter cake is washed with water, the washed filter cake is dried and polished to obtain Cl - SO4 2- and NO3 - The total content of the particles is 50 ppm or less, and the average particle size D 50 A basic rare-earth carbonate having a particle size of 5 μm or less is obtained. The obtained basic rare-earth carbonate is a basic rare-earth carbonate crystal, a basic rare-earth carbonate cluster, or a mixture of basic rare-earth carbonate crystals and basic rare-earth carbonate clusters.

[0050] <Use of carboxylic acid group-containing substances> The present invention has found that an aqueous solution of a carboxylic acid group-containing substance first reacts with a portion of the rare earth carbonate to form a rare earth complex, and the rare earth elements in the rare earth complex exist in the solution as ions. The carboxylic acid group-containing substance promotes the hydrolysis of the rare earth carbonate, and a larger number of carbonate groups and rare earth ions can directly participate in the formation of basic rare earth carbonate, thereby increasing the phase transition rate of the rare earth carbonate. The phase transition rate can be increased by 50 to 200% compared to a pure aqueous solution under the same conditions. A so-called phase transition means the conversion from one form of rare earth carbonate to another form of basic rare earth carbonate. In the process described above, the approximately spherical, large-particle-sized rare earth carbonate is successively crushed and converted into spindle-shaped, small-particle-sized basic rare earth carbonate. The present invention has found that impurities (chloride ions, nitrate ions, sulfate ions, etc.) that exist as one or more types of nanoclusters and nanocrystalline particles, respectively, and that exist in an enclosed and entrained state are released, thereby achieving the objective of reducing the aforementioned impurities.

[0051] Thus, the present invention further provides the use of carboxylic acid group-containing substances to increase the phase transition rate in the process of preparing basic rare earth carbonates from rare earth carbonates. The use comprises (1) a mixing step, (2) a reaction step, and preferably further comprises (3) a conversion step. The specific steps and selection of substances are as described above and are omitted here.

[0052] The measurement method is described below.

[0053] Measurement of chloride ion content: Measured using a T6 new-century ultraviolet-visible spectrophotometer with the mercury thiocyanate spectrophotometer method.

[0054] Measurement of sulfate and nitrate ion content: Measured using an Agilent 5800 inductively coupled plasma mass spectrometer.

[0055] SEM measurement: Measurements are performed using a Sigma-500 scanning electron microscope (FESEM).

[0056] XRD measurement: Measurements are performed using a D8 ADVANE X-ray diffractometer (XRD) manufactured by Bruker GmbH in Germany.

[0057] Particle size distribution: Measured and analyzed using the wet measurement method with the Bettersize2600 laser particle size analyzer.

[0058] Example 1 Cl - Content 360ppm, particle size D 50 We provide 500g of 65μm lanthanum carbonate solid. Prepare an acetic acid solution (an aqueous solution of a substance containing a carboxylic acid group) with a molar concentration of 0.125 mol / L. The lanthanum carbonate solid is added to an acetic acid solution and mixed (the amount of acetic acid used in the acetic acid solution is 7% of the theoretical number of moles required for the complex formation reaction between acetic acid and lanthanum carbonate) to obtain a slurry. The slurry is heated to 70°C and reacted for 60 minutes under conditions of stirring speed of 300 rpm and temperature of 70°C to obtain basic lanthanum carbonate nanoclusters. Alternatively, reacting for 120 minutes yields basic lanthanum carbonate nanocrystalline particles. These are filtered to obtain a filter cake and filtrate. The filtrate is left as is and used for circulation. The filter cake is washed with water, the washed filter cake is dried at 60°C for 4 hours, and polished to obtain particles with a particle size D 50 0.087 μm, Cl - We obtained basic lanthanum carbonate, which is a nanocrystalline particle containing 45 ppm of the substance.

[0059] The SEM results for the obtained basic lanthanum carbonate are shown in Figure 1, and the XRD results are shown in Figure 2.

[0060] Example 2 Cl - Content 320ppm, particle size D 50 We provide 500g of 59μm cerium carbonate solid (cerium carbonate octahydrate). A mixed solution of acetic acid and ammonium acetate (an aqueous solution of a carboxylic acid group-containing substance) was prepared, where the molar concentration of acetic acid in the mixed solution was 0.05 mol / L and the molar concentration of ammonium acetate was 0.01 mol / L. The cerium carbonate solid was added to a mixed solution of acetic acid and ammonium acetate and mixed (the amount of acetic acid used was 5% of the theoretical number of moles required for the complex formation reaction between acetic acid and cerium carbonate, and the amount of ammonium acetate used was 1% of the theoretical number of moles required for the complex formation reaction between ammonium acetate and cerium carbonate) to obtain a slurry. The slurry was heated to 80°C and reacted for 20 minutes under conditions of stirring speed of 300 rpm and temperature of 80°C to obtain cerium carbonate tetrahydrate. After reacting for 60 minutes, basic cerium carbonate nanoclusters were obtained, and after reacting for 120 minutes, basic cerium carbonate nanocrystalline particles were obtained. These were filtered to obtain a filter cake and filtrate. The filtrate was left as is and used for circulation. The filter cake was washed with water, the washed filter cake was dried at 60°C for 4 hours, and polished to obtain a particle size D 50 0.32 μm, Cl - We obtained basic cerium carbonate in the form of nanocrystalline particles with a content of 25 ppm.

[0061] The XRD results of the obtained basic cerium carbonate are shown in Figure 3, and the XRD results of cerium carbonate as a raw material are shown in Figure 4.

[0062] Example 3 SO4 2- Content 320ppm, particle size D 50 We provide 500g of praseodymium neodymium carbonate solid with a particle size of 54μm. A mixed solution of propionic acid and ammonium propionate (used as an aqueous solution of a carboxylic acid group-containing substance) was prepared, where the molar concentration of propionic acid in the mixed solution was 0.03 mol / L and the molar concentration of ammonium propionate was 0.01 mol / L. The praseodymium neodymium carbonate solid was added to a mixed solution of propionic acid and ammonium propionate and mixed (the amount of propionic acid used was 3% of the theoretical number of moles required for the complex formation reaction between propionic acid and praseodymium neodymium carbonate, and the amount of ammonium propionate used was 1% of the theoretical number of moles required for the complex formation reaction between ammonium propionate and praseodymium neodymium carbonate) to obtain a slurry. The slurry was heated to 90°C and reacted for 160 minutes under conditions of stirring speed of 300 rpm and temperature of 90°C to obtain basic praseodymium neodymium carbonate nanoclusters. This was filtered to obtain a filter cake and filtrate. The filtrate was left as is and used for circulation. The filter cake was washed with water, the washed filter cake was dried at 60°C for 4 hours, and polished to obtain a particle size D 50 0.64 μm, SO4 2- We obtained basic praseodymium neodymium carbonate nanoclusters with a content of 40 ppm.

[0063] The SEM results for the obtained basic praseodymium neodymium carbonate are shown in Figure 5.

[0064] Example 4 Cl - Content 360ppm, particle size D 50 We provide 250g of 65μm lanthanum carbonate solid, and Cl - Content 320ppm, particle size D 50 We provide 250g of 59μm cerium carbonate solid. Prepare a 0.09 mol / L propionic acid solution (an aqueous solution of a substance containing a carboxylic acid group), Lanthanum carbonate and cerium carbonate were added together to a propionic acid solution and mixed (the amount of propionic acid used was 9% of the theoretical number of moles required for the complex formation reaction between propionic acid, lanthanum carbonate, and cerium carbonate). A slurry was obtained, the slurry was heated to 90°C, and reacted for 160 minutes under conditions of stirring speed of 300 rpm and temperature of 90°C to obtain basic lanthanum cerium carbonate nanoclusters. This was filtered to obtain a filter cake and filtrate. The filtrate was left as is and used for circulation, and the filter cake was washed with water. The washed filter cake was dried at 60°C for 4 hours and polished to obtain particle size D 50 2.64 μm, SO4 2- We obtained basic cerium lanthanum carbonate nanoclusters with a content of 40 ppm.

[0065] Example 5 NO3 - Content 290ppm, particle size D 50 We provide 500g of 45μm samarium carbonate solid. Prepare a formic acid solution (an aqueous solution of a carboxylic acid group-containing substance) with a molar concentration of 0.05 mol / L. Samarium carbonate was added to a formic acid solution and mixed (the amount of formic acid used was 9% of the theoretical number of moles required for the complex formation reaction between formic acid and samarium carbonate). A slurry was obtained, the slurry was heated to 100°C, and reacted for 300 minutes at a stirring speed of 300 rpm and a temperature of 100°C to obtain basic samarium carbonate nanoclusters. This was filtered to obtain a filter cake and filtrate. The filtrate was left as is and used for circulation. The filter cake was washed with water, and the washed filter cake was dried at 60°C for 4 hours and polished to obtain a particle size D 50 3.4 μm, NO3 - We obtained basic samarium carbonate nanoclusters with a content of 35 ppm.

[0066] Example 6 NO3 - Content 240ppm, particle size D 50 We provide 500g of 53μm europium carbonate solid. A mixed solution of formic acid, acetic acid, and propionic acid (an aqueous solution of a carboxylic acid group-containing substance) was prepared, where the molar concentrations of formic acid, acetic acid, and propionic acid were all 0.01 mol / L. Europium carbonate was added to a mixed solution of formic acid, acetic acid, and propionic acid and mixed (the amount of formic acid used was 3% of the theoretical number of moles required for the complex formation reaction between formic acid and europium carbonate; the amount of acetic acid used was 3% of the theoretical number of moles required for the complex formation reaction between acetic acid and europium carbonate; and the amount of propionic acid used was 3% of the theoretical number of moles required for the complex formation reaction between propionic acid and europium carbonate). A slurry was obtained, the slurry was heated to 95°C, and reacted at a stirring speed of 300 rpm and a temperature of 95°C for 400 minutes to convert europium carbonate into basic europium carbonate nanoclusters, and filtered to obtain a filter cake and filtrate. The filtrate was left as is and used for circulation. The filter cake was washed with water, and the washed filter cake was dried at 60°C for 4 hours and polished to obtain a particle size D 50 4.2 μm, NO3 - We obtained basic europium carbonate in the form of nanoclusters with a content of less than 50 ppm.

[0067] The XRD and SEM results of the obtained basic europium carbonate are shown in Figures 6 and 7, respectively.

[0068] Example 7 Cl - Content 280ppm, particle size D 50 We provide 500 gadolinium carbonate solids with a particle size of 56 μm. A mixture solution of formic acid, ammonium formate, acetic acid, and ammonium acetate (an aqueous solution of a carboxylic acid group-containing substance) was prepared, with the molar concentrations of formic acid and ammonium formate being 0.05 mol / L each, and the molar concentrations of acetic acid and ammonium acetate being 0.03 mol / L each. Add gadolinium carbonate to an aqueous solution of the carboxylic acid group-containing substance, mix (the total number of moles of formic acid and ammonium formate is 5% of the theoretical number of moles required for the complex formation reaction between formic acid and gadolinium element in gadolinium carbonate, the molar ratio of formic acid to ammonium formate is 5:1, the total number of moles of acetic acid and ammonium acetate is 3% of the theoretical number of moles required for the complex formation reaction between acetic acid and gadolinium element in gadolinium carbonate, and the molar ratio of acetic acid to ammonium acetate is 5:1.), to obtain a slurry, heat the slurry to 95 °C, react at a stirring speed of 300 rpm and a temperature of 95 °C for 600 min, convert gadolinium carbonate into a mixture of nanoclusters and nanocrystalline particles of basic gadolinium carbonate, filter to obtain a filter cake and a filtrate, leave the filtrate as it is for recycling use, wash the filter cake with water, dry the washed filter cake at 60 °C for 4 h, and polish to obtain a particle size D 50 4.6 μm, Cl - A mixture of nanoclusters and nanocrystalline particles of basic gadolinium carbonate with a Cl content of 42 ppm was obtained.

[0069] Example 8 Cl - With a content of 320 ppm and a particle size D 50 59 μm, 200 g of cerium carbonate solid was provided, with a NO3 - With a content of 290 ppm and a particle size D 50 45 μm, 300 g of samarium carbonate solid was provided.

[0070] Prepare a mixed solution of propionic acid, ammonium propionate, acetic acid and ammonium acetate (aqueous solution of carboxylic acid group-containing substance), where the molar concentrations of propionic acid and ammonium propionate are each 0.15 mol / L, and the molar concentrations of acetic acid and ammonium acetate are each 0.015 mol / L.

[0071] Add cerium carbonate and samarium carbonate to the aqueous solution of the carboxylic acid group-containing substance, mix (the total number of moles of propionic acid and ammonium propionate is 9% of the theoretical number of moles required for the complex formation reaction between propionic acid and cerium and samarium elements in cerium carbonate and samarium carbonate, the molar ratio of propionic acid to ammonium propionate is 3:1, the total number of moles of acetic acid and ammonium acetate is 1% of the theoretical number of moles required for the complex formation reaction between acetic acid and cerium and samarium elements, and the molar ratio of acetic acid to ammonium acetate is 3:1.), to obtain a slurry, heat the slurry to 90 °C, and react for 450 min under the conditions of a stirring speed of 300 rpm and a temperature of 90 °C to convert cerium carbonate and samarium carbonate into basic cerium samarium carbonate nanocrystalline particles, filter to obtain a filter cake and a filtrate, leave the filtrate as it is for recycling use, wash the filter cake with water, dry the washed filter cake at 60 °C for 4 h, and polish to obtain a particle diameter D 50 0.64 μm, Cl - and NO3 - To obtain basic cerium samarium carbonate as nanocrystalline particles with a total content of less than 50 ppm.

[0072] Ratio 1 This comparative example was different from Example 2 in that an aqueous solution of a carboxylic acid group-containing substance was not added.

[0073] As a specific step, add cerium carbonate solid to pure water to obtain a slurry, and the other reaction conditions were the same as those in Example 2. After reacting for 20 min, cerium carbonate was not completely converted. After reacting for 120 min, what was obtained was a mixture of cerium carbonate and basic cerium carbonate. After reacting for 180 min, what was obtained was basic cerium carbonate in the form of micron clusters. Filter this to obtain a filter cake and a filtrate, leave the filtrate as it is for recycling use, wash the filter cake with water, dry the washed filter cake at 60 °C for 4 h to obtain basic cerium carbonate with a particle diameter D 50 12.54 μm, Cl - Content 85 ppm of basic cerium carbonate was obtained.

[0074] The SEM results of the obtained basic cerium carbonate are shown in Figure 8. The XRD results of the starting material, intermediate product, and product are shown in Figure 9.

[0075] Ratio Proportionality 2 This proportional ratio differed from Example 6 in that no aqueous solution of the carboxylic acid group-containing substance was added.

[0076] The specific steps involved adding europium carbonate solid to pure water to obtain a slurry, with the other reaction conditions being the same as in Example 6. After reacting for 400 minutes, the europium carbonate was not completely converted, and the result was a mixture of europium carbonate and basic europium carbonate. This was filtered to obtain a filter cake and filtrate. The filtrate was left as is and reused in a recirculating manner. The filter cake was washed with water, and the washed filter cake was dried at 60°C for 4 hours to form micron-spherical particles with a particle size of D 50 46 μm, NO3 - A mixture of europium carbonate with a content of 215 ppm and basic europium carbonate was obtained.

[0077] The SEM results of the obtained products are shown in Figure 10. The XRD results of the intermediate products and reaction products are shown in Figure 11.

[0078] The present invention is not limited to the embodiments described above, and any modifications, improvements, or substitutions conceivable by those skilled in the art, without departing from the spirit of the invention, are all included within the scope of the present invention.

Claims

1. A step of mixing a rare earth carbonate with an aqueous solution of a carboxylic acid group-containing substance to obtain a slurry, The steps include heating the slurry to cause a reaction, A method for increasing the phase transition rate in the process of preparing a basic rare earth carbonate from a rare earth carbonate, characterized by including the following: The aforementioned phase transition rate increases compared to that of a pure aqueous solution under the same conditions. A phase transition refers to the conversion from one form of rare-earth carbonate to another form of basic rare-earth carbonate. A method for increasing the phase transition rate during the process of preparing basic rare-earth carbonates from rare-earth carbonates.

2. A step of mixing a rare earth carbonate with an aqueous solution of a carboxylic acid group-containing substance to obtain a slurry, The steps include heating the slurry to react and obtain an intermediate product, A step of converting the intermediate product into basic rare earth carbonate crystals, basic rare earth carbonate clusters, or a mixture of basic rare earth carbonate crystals and basic rare earth carbonate clusters. A method for preparing a basic rare earth carbonate from a rare earth carbonate, characterized by containing [a specific compound / component].

3. The aforementioned carboxylic acid group-containing substance is (1) C1-C6 monovalent carboxylic acids, (2) A mixture of a C1-C6 monovalent carboxylic acid and a C1-C6 monovalent ammonium carboxylic acid salt, The method according to claim 1 or claim 2, characterized in that it is selected from.

4. The C1-C6 monovalent carboxylic acid is one or more selected from formic acid, acetic acid, and propionic acid. The mixture of the C1-C6 monovalent carboxylic acid and the C1-C6 monovalent ammonium carboxylic acid salt is a mixture of formic acid and ammonium formate, a mixture of acetic acid and ammonium acetate, or a mixture of propionic acid and ammonium propionate. The method according to claim 3, characterized in that it is selected from.

5. The amount of the carboxylic acid group-containing substance used is 1 to 9% of the theoretical number of moles required for the complex formation reaction between the carboxylic acid group-containing substance and the rare earth element in the rare earth carbonate. The method according to claim 1 or claim 2, characterized in that the concentration of the carboxylic acid group-containing substance in an aqueous solution of the carboxylic acid group-containing substance is 0.015 to 0.15 mol / L.

6. The method according to claim 1 or 2, characterized in that the slurry is heated to 50 to 100°C and reacted for 10 to 600 minutes.

7. The intermediate product is converted into basic rare-earth carbonate crystals, basic rare-earth carbonate clusters, or a mixture of basic rare-earth carbonate crystals and basic rare-earth carbonate clusters, followed by solid-liquid separation, and the resulting filtrate is recycled and reused as an aqueous solution of a carboxylic acid group-containing substance. The method according to claim 1 or 2, further comprising:

8. Cl in rare earth carbonate － , SO ４ ２－ and NO ３ － The total content of is more than 120 ppm, and the total content of Cl － , SO ４ ２－ and NO ３ － in basic rare earth carbonate is 50 ppm or less than 50 ppm, Average particle size D of basic rare earth carbonates ５０ The method according to claim 1 or 2, characterized in that the particle is less than 5.5 μm.

9. The use of a carboxylic acid group-containing substance, characterized in that it is used to increase the phase transition rate in the process of preparing a basic rare earth carbonate from a rare earth carbonate compared to a pure aqueous solution under the same conditions, A phase transition refers to the conversion from one form of rare-earth carbonate to another form of basic rare-earth carbonate. Use of substances containing carboxylic acid groups.

10. The aforementioned carboxylic acid group-containing substance is (1) C1-C6 monovalent carboxylic acids, (2) A mixture of a C1-C6 monovalent carboxylic acid and a C1-C6 monovalent ammonium carboxylic acid salt, The use according to claim 9, characterized in that it is selected from among.

Images