Preparation method of low-chlorine alkaline rare earth carbonate
By reacting chloride rare earths with monomer carboxyl groups and precipitant solution under low temperature conditions, low chlorine-alkali carbonate rare earths are prepared, which solves the problem of high chloride ion content in the prior art, and achieves low energy consumption, simplified process and high efficiency alkalis Preparation of carbonate rare earths, suitable for industrial production.
Patent Information
- Application Number
- CN202411393141.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2024-12-27
AI Technical Summary
The process of preparing alkali carbonate rare earths in the prior art has a high chloride ion content, resulting in high energy consumption and complex process, which limits its industrial production. The existing methods require long-term standstill or high-temperature reactions, which reduces working efficiency and Product quality.
Under low temperature conditions, the chloride rare earth solution is mixed with a monocarboxyl-containing substance and a precipitant solution (including NH3·H2O and NH4HCO3) to prepare low-chlorine-alkali carbonate rare earths. By controlling the reaction temperature and pH value, the chloride ions are reduced. Package, simplify the process.
It realizes low energy consumption preparation of low chlorine-alkali carbonate rare earths, reduces the chlorine content, simplifies the process flow, improves production efficiency and product particle size uniformity, and is suitable for industrial production.
Smart Images
Figure CN119191330A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of rare earth compound preparation, and in particular to a method for preparing low-chlorine alkaline rare earth carbonate. Background Art
[0002] Basic rare earth carbonate is an intermediate for preparing rare earth oxide. Studies have found that the use of basic rare earth carbonate to prepare rare earth oxide can not only reduce energy consumption and carbon emissions, but also help to prepare high-density rare earth oxide. However, the chloride ion content in the products of the currently disclosed process for preparing basic rare earth carbonate is relatively high. The solution is mainly high-temperature reaction, which requires long-term aging to promote product crystal growth and complex multiple process impurity removal methods, which greatly limits the industrial production of low-chloride basic rare earth carbonate. Therefore, the development of a preparation process with low energy consumption, simple process flow, and the ability to reduce the chloride ion content in basic rare earth carbonate will help the large-scale industrial application of basic rare earth carbonate.
[0003] CN 116924450A discloses a method for preparing basic rare earth carbonate from rare earth chloride solution, wherein the rare earth chloride solution and a precipitant solution are added dropwise to water at 35-45°C in a parallel flow manner to form a mixed solution with a pH of 6.5-7.5, and the mixture is allowed to stand for more than 6 hours after the addition is completed, and the chloride ion content in the prepared basic rare earth carbonate is less than 0.05wt%. This method requires standing for more than 6 hours after the reaction to reduce the chloride ion content, which greatly reduces the work efficiency.
[0004] CN 116789161 A discloses a method for preparing high-purity lanthanum carbonate alkali, which uses lanthanum carbonate as a raw material, dissolves lanthanum carbonate slurry with industrial hydrochloric acid or industrial nitric acid to obtain lanthanum chloride or lanthanum nitrate liquid, and obtains high-purity lanthanum chloride or lanthanum nitrate crystals through concentration and crystallization; the high-purity lanthanum chloride or lanthanum nitrate crystals are then prepared into lanthanum chloride or lanthanum nitrate solution, and a mixed solution of ammonium bicarbonate and ammonia water is used as a precipitant to prepare high-purity lanthanum carbonate alkali, wherein Fe, Ca, Na, K, Pb, Zn, Mn, Al, Cu, Ni, Co, and Cr in the product are less than 1ppm. This method also uses rare earth chloride raw materials to prepare rare earth carbonate alkali, but the process is cumbersome, which is not conducive to industrial scale-up production, and the chloride ion content in the product is not tested.
[0005] CN103708525B discloses a method for producing a high bulk density fine-grained low-chloride rare earth carbonate and oxide. The invention uses rare earth carbonate as a raw material, and obtains a low-chloride, fine-grained, high-bulk density basic carbonate through phase transformation. The chloride content of the basic carbonate prepared by the method is 166ppm. However, the method directly uses rare earth carbonate as a raw material, the raw material cost is high, and the phase transformation needs to be achieved at high temperature. The process is complicated, the energy consumption is high, and the reaction process is difficult to control, which is not suitable for industrial production.
[0006] CN 117865204A discloses a method for reducing the chlorine content in rare earth oxides and the use of ammonium acetate solution. The invention can reduce the chlorine content in the obtained precursor by dropping rare earth chloride solution and ammonia water into ammonium acetate solution in parallel, thereby reducing the chlorine content in the obtained rare earth oxide. The volume of ammonium acetate used in the method is one-half to three-quarters of the sum of the volumes of the rare earth chloride solution and ammonia water. As an acid-base stabilizer, the pH value in the reaction process is reduced to control the concentration of hydroxide ions, thereby reducing the relative supersaturation of the rare earth oxide precursor, inhibiting the nucleation rate of the precipitated crystal, and promoting the growth of the crystal to reduce the Cl content in the rare earth oxide precursor. - This method uses a large amount of volatile ammonium acetate, which is costly and easily causes environmental pollution during large-scale preparation. Long-term exposure will affect the health of operators. Summary of the invention
[0007] In view of this, the present invention provides a method for preparing low-chlorine basic rare earth carbonate. The method of the present invention can obtain basic rare earth carbonate under low temperature conditions without aging; the method of the present invention can obtain basic rare earth carbonate with low chloride content under the condition of using a small amount of organic solvent.
[0008] To achieve the above object, the present invention provides the following solutions:
[0009] The present invention provides a method for preparing low-chlorine alkaline rare earth carbonate, comprising the following steps:
[0010] The rare earth chloride solution is mixed with a precipitant solution and a substance containing a monocarboxyl group to react, thereby obtaining the low-chlorine alkaline rare earth carbonate;
[0011] The precipitant solution includes NH 3 ·H 2 O and NH 4 HCO 3 .
[0012] The present invention discloses the following technical effects:
[0013] Compared with the existing disclosed method for preparing basic rare earth carbonate, the method of the present invention has a low reaction temperature, does not require aging, reduces energy consumption in the production process, uses very little organic reagent, has a simple process flow, and is easy to scale up industrially.
[0014] The low-chlorine alkaline rare earth carbonate prepared by the method of the invention has a small and uniform particle size, and a chloride content lower than 1000 ppm. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0016] Figure 1 This is the XRD pattern of lanthanum basic carbonate prepared in Example 1.
[0017] Figure 2 This is the SEM image of the lanthanum carbonate hydroxide prepared in Example 1. DETAILED DESCRIPTION
[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0019] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.
[0020] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.
[0021] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.
[0022] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.
[0023] In the present invention, REO represents rare earth oxide; chloride ion may also be referred to as chloride ion.
[0024] The present invention has found that adding a small amount of carboxyl-containing substance solution to a rare earth chloride solution and a mixed precipitant solution for reaction can prepare low-chloride basic rare earth carbonate under the condition of no aging.
[0025] The present invention provides a method for preparing low-chlorine alkaline rare earth carbonate, comprising the following steps:
[0026] The rare earth chloride solution is mixed with a precipitant solution and a substance containing a monocarboxyl group to react, thereby obtaining the low-chlorine alkaline rare earth carbonate;
[0027] The precipitant solution includes NH 3 ·H 2 O and NH 4 HCO 3 .
[0028] In some embodiments of the present invention, the NH 3 ·H 2 O and the NH 4 HCO 3 The molar ratio of is 1.6 to 2.2:1. Preferably, it is 1.8 to 2.15:1, and more preferably, it is 2 to 2.1:1. In the present invention, aqueous ammonia is used in the form of a solution. Ammonium bicarbonate can be used in the form of a solid powder or a solution. Both aqueous ammonia and ammonium bicarbonate can provide NH 4 + In the mixed precipitant solution, NH 4 + The concentration can be 2-6 mol / L, preferably 2-5 mol / L, and more preferably 2.5-4 mol / L. The precipitant solution with the above-mentioned molar ratio of ammonia water to ammonium bicarbonate can generate a crystalline basic rare earth carbonate and help reduce impurities in the reaction product. A molar ratio of ammonia water to ammonium bicarbonate exceeding the above ratio will affect the crystal form and is not conducive to reducing impurities in the reaction product.
[0029] In some embodiments of the present invention, the rare earth ions in the rare earth chloride solution and the NH 4 + The molar ratio is 1:2.8 to 3.5, preferably 1:3 to 3.45, and more preferably 1:3.15 to 3.45.
[0030] In some embodiments of the present invention, the rare earth element in the rare earth chloride solution is lanthanum and / or cerium. In certain embodiments, the rare earth element in the rare earth chloride solution is lanthanum. In other embodiments, the rare earth element in the rare earth chloride solution is cerium.
[0031] In some embodiments of the present invention, the monocarboxyl group-containing substance is a monocarboxylic acid and / or a monocarboxylate salt.
[0032] In some embodiments of the present invention, the monocarboxylic acid is at least one of formic acid, acetic acid, and propionic acid; and the monocarboxylate is an alkali metal monocarboxylate or ammonium monocarboxylate.
[0033] In some embodiments of the present invention, the amount of the monocarboxyl-containing substance added is 3%-10% of the total mass of the rare earth in the rare earth chloride solution, calculated as REO.
[0034] In some embodiments of the present invention, the reaction temperature is 40 to 60°C. Preferably, it is 45 to 60°C. In the present invention, it is necessary to control the temperature of the reaction system. In certain embodiments, the temperature is 50 to 60°C. This can improve the uniformity of particle size. When the temperature is higher than 60°C, the grain growth rate is accelerated, the particle size of the resulting product monomer becomes larger, and the chloride ions are easily wrapped in the crystals, resulting in a high chloride ion content.
[0035] In some embodiments of the present invention, the endpoint pH value of the reaction is 6.2-7.0.
[0036] Controlling the above parameters within the parameter range described in the present invention helps to slow down the nucleation rate of the crystal, control the crystal particles within 5 μm, and reduce the encapsulation of chloride ions.
[0037] After the reaction is completed, the steps of filtering, washing and drying are also included. In some embodiments, after filtering, 3-6 times the mass of the solid is used for rinsing. In other embodiments, the filtered product can be dispersed in 3-5 times the mass of water, stirred and washed, and then filtered.
[0038] The mother liquor from solid-liquid separation during filtration can be recycled and used as one or more of the solvent for the precipitant solution, the bottom liquid, and the solvent for the rare earth chloride solution.
[0039] The chloride ion content in the basic rare earth carbonate prepared by the method of the present invention is less than 1000 ppm, preferably less than 800 ppm, and more preferably less than 500 ppm.
[0040] Rare earth oxides can be obtained by roasting the low-chlorine alkaline rare earth carbonate prepared by the method of the invention.
[0041] The test method involved in the present invention is:
[0042] (1) Determination of chloride ion content: According to the national standard GB / T 12690, the test was carried out using the silver nitrate turbidimetric method.
[0043] (2) Determination of rare earth content: According to the national standard GB / T 14635-2008, the rare earth content was tested by EDTA complexometric titration.
[0044] (3) X-ray diffraction: The test was performed using an X-ray powder diffractometer (model: X Pert PRO) from PANalytical, the Netherlands.
[0045] (4) SEM: The test was performed using a ZEISS Sigma 500 field emission scanning electron microscope.
[0046] Unless otherwise specified, the raw materials and reagents used in the following examples can be obtained through commercial sources.
[0047] The precipitant solution in the present invention is composed of NH 3 ·H 2 O and NH 4 HCO 3 Dissolved in water.
[0048] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0049] Example 1
[0050] At 50°C, 200 mL of 264 g / L lanthanum chloride solution and 427 mL of a mixed precipitant solution (NH 2 in the precipitant solution) prepared by a 2:1 molar ratio of ammonia water and ammonium bicarbonate were added. 4 + The reaction was completed when the pH of the reaction system reached 6.2.
[0051] The precipitated product was vacuum filtered and rinsed with water 3 times the weight of the solid. After washing, it was dried at 60° C. for 8 h to obtain lanthanum carbonate hydroxide with a chloride content of 435 ppm. Figure 1 , Figure 2 The XRD and SEM images of the lanthanum carbonate hydroxide obtained in Example 1 are shown respectively. Figure 2 It can be seen that the particle size of the lanthanum carbonate hydroxide prepared in this embodiment is about 3.5 μm and the size is uniform.
[0052] Example 2
[0053] At 45°C, 200 mL of 264 g / L lanthanum chloride solution and 400 mL of a mixed precipitant solution (NH 2 in the precipitant solution) prepared by a molar ratio of 2.1:1 of ammonia water and ammonium bicarbonate were added. 4 +The ion concentration is 2.6 mol / L) and 3 g of ammonium acetate are mixed for reaction. When the pH of the reaction system is 6.4, the reaction is completed.
[0054] The precipitated product was vacuum filtered and rinsed with water 4 times the weight of the solid, and then dried at 60° C. for 8 h to obtain lanthanum carbonate hydroxide with a chloride content of 800 ppm.
[0055] Example 3
[0056] At 45°C, 200 mL of 300 g / L cerium chloride solution and 400 mL of a mixed precipitant solution (NH 2+ in the precipitant solution) prepared with a molar ratio of 1.9:1 of ammonia water and ammonium bicarbonate were added. 4 + The reaction was completed when the pH of the reaction system reached 6.8.
[0057] The precipitated product was vacuum filtered and rinsed with water 5 times the weight of the solid. After washing, it was dried at 60° C. for 8 h to obtain basic cerium carbonate with a chloride content of 640 ppm.
[0058] Example 4
[0059] At 55°C, 200 mL of 310 g / L lanthanum cerium chloride solution and 470 mL of a mixed precipitant solution (NH 2 in the precipitant solution) prepared by a 2:1 molar ratio of ammonia water and ammonium bicarbonate were added. 4 + The reaction was completed when the pH of the reaction system reached 6.8.
[0060] The precipitated product was vacuum filtered and dispersed in water with a solid mass of 5 times, stirred and washed, and then filtered again. After washing, it was dried at 60° C. for 8 h to obtain lanthanum cerium carbonate basic with a chloride content of 536 ppm.
[0061] Example 5
[0062] At 50°C, 200 mL of 300 g / L cerium chloride solution and 400 mL of a mixed precipitant solution (NH 2 in the precipitant solution) prepared with a molar ratio of 2:1 of ammonia water and ammonium bicarbonate were added. 4 + The reaction was completed when the pH of the reaction system reached 6.6.
[0063] The precipitated product was vacuum filtered and rinsed with water 4 times the weight of the solid. After washing, it was dried at 60° C. for 8 h to obtain basic cerium carbonate with a chloride content of 762 ppm.
[0064] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.
Claims
1. A method for preparing low-chlorine alkaline rare earth carbonate, characterized in that: The following steps are involved: The rare earth chloride solution is mixed with a precipitant solution and a substance containing a monocarboxyl group to react, thereby obtaining the low-chlorine alkaline rare earth carbonate; The precipitant solution includes NH3·H2O and NH4HCO3.
2. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: The molar ratio of the NH3·H2O to the NH4HCO3 is 1.6-2.2:
1.
3. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: The rare earth ions in the rare earth chloride solution and the NH4 + The molar ratio is 1:2.8~3.
5.
4. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: The rare earth elements in the rare earth chloride solution are lanthanum and / or cerium.
5. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: The substance containing a monocarboxyl group is a monocarboxylic acid and / or a monocarboxylate salt.
6. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 5, characterized in that: The monocarboxylic acid is at least one of formic acid, acetic acid and propionic acid; the monocarboxylate is an alkali metal monocarboxylate or ammonium monocarboxylate.
7. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: Calculated in terms of REO, the added amount of the substance containing a monocarboxyl group is 3%-10% of the total mass of the rare earth in the rare earth chloride solution.
8. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: The reaction temperature is 40-60°C.
9. The method for preparing low-chlorine alkaline rare earth carbonate according to claim 1, characterized in that: The endpoint pH value of the reaction is 6.2-7.0.