Method for reducing impurities in rare earth concentrate
By treating rare earth concentrates with a mixture of low-concentration hydrochloric acid and phosphoric acid, and combining extraction and precipitation methods, the problems of low rare earth recovery rate and serious pollution in rare earth concentrate extraction were solved, achieving efficient and environmentally friendly rare earth purification.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-03-27
AI Technical Summary
Existing rare earth concentrate extraction processes suffer from low rare earth recovery rates, high costs, and severe pollution, especially when processing rare earth minerals from the Bayan Obo mining area, where impurity elements are difficult to remove effectively.
Rare earth concentrate is treated with a mixture of low-concentration hydrochloric acid and low-concentration phosphoric acid. Solid-liquid separation is then performed by heating, holding, and pressurizing the solution. This is combined with N235 extraction and dilute sulfuric acid precipitation to reduce impurity content and improve rare earth recovery rate.
It achieves a rare earth recovery rate of up to 99% in rare earth concentrate, reduces impurity content, simplifies the process, and reduces the generation of waste gas and wastewater, making it suitable for industrial-scale production.
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Figure CN121737487A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of rare earth ore dressing, and particularly relates to a method for reducing impurities of rare earth concentrate. BACKGROUND
[0002] Baotou ore district has more than 175 kinds of minerals and 71 kinds of elements, in which, the iron ore reserves are 1.4 billion tons, the niobium ore reserves are 6.6 million tons, and the industrial reserves of rare earth ore are 36 million tons, which is the center of rare earth in the north of China, and the total amount reaches several hundred million tons, and is called "the hometown of rare earth". Monazite is a phosphate mineral containing cerium and lanthanum, and is a kind of rare earth mineral, and the Chinese name is "phosphor cerium lanthanum ore", and (Ce, Y, La, Th) PO4 is the main mineral for refining cerium and lanthanum. Light rare earth (cerium group) oxide accounts for 39-74%, and heavy rare earth (yttrium group) oxide accounts for 0-5%, and the rare earth elements are widely used in the fields of black and non-ferrous metallurgy, glass and ceramic production, electronics, electrical lighting, television and laser technology, chemical industry, medical treatment and agricultural production. Bastnaesite is a cerium group rare earth element (light rare earth) mineral with important industrial value, and belongs to the type of fluorocarbonate. The content of rare earth elements (calculated by REO) is generally 75%, and is radioactive and weakly magnetic, the rare earth salt in the mineral is slightly soluble in dilute hydrochloric acid and sulfuric acid, and the impurity elements in the mineral are rapidly decomposed in acid. Bastnaesite is mainly produced in alkaline rocks, alkaline pegmatite and related hydrothermal deposits, is an important mineral raw material for extracting cerium and lanthanum, and can also be used for synthesizing rubber, artificial fibers, organic synthesis and the like.
[0003] The "Green Chemistry Progress of Bastnaesite Extraction of Rare Earth" points out that the oxidation roasting-hydrochloric acid leaching method is a classical method for decomposing bastnaesite concentrate proposed by the American Molybdenum Company in 1965. The process repeatedly converts the rare earth form, and the liquid-solid separation operation is multiple, and the process is long; in addition, there are SiF4, HCl and other waste gas, fluorine-containing waste water. The rare earth extraction rate is low, the chemical material consumption is large, and the waste discharge is much, and it is a process with relatively low technical level.
[0004] The "Optimization of Separation of Rare Earth and Fluorine Aluminum in Baotou Rare Earth Concentrate Complex Leaching Solution" points out that the concentrated sulfuric acid roasting method is the most important method for decomposing Baotou rare earth ore in the industry at present due to the advantages of simple process, convenient operation, low running cost and realization of large-scale production. The third generation of sulfuric acid process method is the most commonly used method in the industry at present, and more than 90% of mixed rare earth ore adopts the method for treatment. The production cost of this process is low, the operation is simple, it is easy to large-scale production, and the purity and recovery rate of rare earth are high, but the "three wastes" pollution problems caused by this process are very serious, including radioactive waste residue containing thorium, recovery difficulty of sulfur and fluorine waste gas, and a large amount of waste water generated in the extraction process.
[0005] The concentrated hydrochloric acid method leaching of rare earth concentrate has large raw material loss, low rare earth recovery rate, and long holding time in the reaction process, in order to overcome the above deficiencies, the application improves the raw material and process for the purification reaction of the rare earth concentrate. SUMMARY
[0006] The application aims to provide a method for reducing impurities in rare earth concentrate, using dilute hydrochloric acid and dilute phosphoric acid to purify the rare earth concentrate, which reduces the cost, simplifies the process and improves the rare earth recovery rate compared with the oxidation roasting-hydrochloric acid leaching method and concentrated sulfuric acid roasting method.
[0007] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: The application provides a method for reducing impurities in rare earth concentrate, the original rare earth concentrate contains one or both of phosphor cerium lanthanide and fluorocarbon cerium minerals, and the rare earth grade of the original rare earth concentrate is REO content > 50%; the method comprises: adding low-concentration acid and original rare earth concentrate into a reaction kettle, heating, holding and pressurizing for a period of time, then cooling, and then performing solid-liquid separation to obtain high-purity secondary rare earth concentrate; the low-concentration acid is a mixed acid of low-concentration hydrochloric acid and low-concentration phosphoric acid; the concentration of the low-concentration hydrochloric acid is 4-8 mol / L; and the concentration of the low-concentration phosphoric acid is 3-5 mol / L.
[0008] Further, the volume ratio of the low-concentration hydrochloric acid to the low-concentration phosphoric acid in the mixed acid is 3:1-5:1.
[0009] Further, the original rare earth concentrate is a finely ground rare earth concentrate with a particle size of less than or equal to 200 mesh; And / or, the acid-mineral mass ratio of the added low-concentration acid and original rare earth concentrate is 1.5:1-2:1.
[0010] Further, the heating and holding is heating to 120-160 DEG C and holding; and / or, the holding and pressurizing time is 2-4 h; and / or, the pressurizing pressure is 0.1-0.3 MPa; and / or, the cooling temperature is less than 80 DEG C.
[0011] Further, the solid-liquid separation is performed by filtration; and the rare earth grade of the secondary rare earth concentrate obtained after the solid-liquid separation is REO content > 68%, CaO content < 2%, and rare earth recovery rate > 99%.
[0012] Further, the solution obtained after the solid-liquid separation contains calcium chloride, calcium phosphate, ferric chloride and rare earth phosphate.
[0013] Further, the solution obtained after the solid-liquid separation is subjected to iron removal by N235 extraction to obtain an iron-removed solution.
[0014] Further, the solution after removing iron is added with calcium salt in dilute sulfuric acid to precipitate calcium sulfate and waste acid solution containing rare earth phosphate, which is used as a substitute for the low-concentration acid or the rare earth is recovered from the solution by solvent extraction, chemical precipitation or ion exchange.
[0015] Further, the mass percentage of impurity fluorite in the original rare earth concentrate is 2.5%-3.5%.
[0016] The method for reducing impurities in rare earth concentrate provided by the application has the following beneficial effects: (1) The addition of phosphoric acid can increase the boiling point of the solution, reduce the loss of HCl due to volatilization, and inhibit the dissolution of rare earth ions. The use of dilute hydrochloric acid can save raw materials, simplify the process, shorten the production time, improve the recovery rate of rare earth, and reduce the content of calcium in the secondary rare earth concentrate.
[0017] (2) The method can obtain a rare earth concentrate with a content of more than 68% in an industrial production scene, and the overall process has less loss of rare earth. The calcium sulfate obtained after acid leaching can also be recovered as a byproduct.
[0018] (3) The method can be directly applied to an industrial scene and is suitable for places with high requirements for rare earth grade. For example, in the process of mineral development, impurities may include fluorite and other difficult-to-leach minerals. The method uses Baiyunebo minerals as raw materials, and the fluorite content is relatively high. The method can also obtain a rare earth concentrate with a content of more than 68%.
[0019] (4) The method does not have waste gas problems, and the reaction is carried out in a closed environment. The pickling solution is recycled after calcium removal, and no waste water is generated. BRIEF DESCRIPTION OF DRAWINGS
[0020] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.
[0021] Figure 1 The rare earth concentrate purification flowchart provided by the embodiments of the application. DETAILED DESCRIPTION
[0022] In order to make the objectives, technical solutions and advantages of the present application clearer, the following will combine the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. It should be understood by those skilled in the art that the embodiments are only used to understand the present application and should not be regarded as a specific limitation to the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application. The process parameters not specified in the following embodiments are usually according to the conventional conditions.
[0023] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values stated. The ranges or values should be interpreted as approximately between the stated values. For ranges, the endpoints are included between each respective range; the endpoints are included in the respective range or point. For ranges, the endpoints are included between each respective range; the endpoints are included in the respective range or point.
[0024] The present application provides a method for reducing impurities in rare earth concentrate, the original rare earth concentrate contains one or both of monazite (monazite) and bastnaesite, the rare earth grade in the original rare earth concentrate is REO content > 50% (such as: 52%, 55%, 58%, 60%, 65%, 68%, etc.); the method comprises: adding low concentration acid, original rare earth concentrate in the reaction kettle, heating, holding and pressure for a period of time, then cooling, and then carrying out solid-liquid separation to obtain high-purity secondary rare earth concentrate; the low concentration acid is a mixed acid of low concentration hydrochloric acid and low concentration phosphoric acid; the concentration of the low concentration hydrochloric acid is 4-8 mol / L (such as 4.5 mol / L, 5.0 mol / L, 5.5 mol / L, 6.0 mol / L, 6.5 mol / L, 7.0 mol / L, 7.5 mol / L); the concentration of the low concentration phosphoric acid is 3-5 mol / L (such as 3.5 mol / L, 4.0 mol / L, 4.5 mol / L, 4.8 mol / L).
[0025] The low concentration acid used in the present application adds phosphoric acid because phosphoric acid can raise the boiling point of the solution, reduce the loss of HCl due to volatilization, simplify the process, shorten the production time, improve the recovery rate of rare earth, and reduce the content of calcium in the product.
[0026] As an optional embodiment of the present application, the volume ratio of low concentration hydrochloric acid and low concentration phosphoric acid in the mixed acid is 3:1-5:1 (such as 3.5:1, 4.0:1, 4.5:1).
[0027] As an optional embodiment of the present application, the original rare earth concentrate is a finely ground rare earth concentrate with a particle size of less than or equal to 200 mesh. And / or, the acid ore mass ratio of the low concentration acid added to the primary rare earth concentrate is 1.5:1-2:1 (such as 1.6:1, 1.7:1, 1.8:1, 1.9:1).
[0028] As an optional embodiment of the present application, the temperature rising and holding is rising to 120-160 DEG C (such as 130 DEG C, 140 DEG C, 150 DEG C) and holding;And / or, the holding time is 2-4 h (such as 2.5 h, 3 h, 3.5 h);And / or, the pressure holding pressure is 0.1-0.3 Mpa;And / or, the cooling temperature is less than 80 DEG C. The cooling is carried out by cooling water through the reaction kettle coil.
[0029] As an optional embodiment of the present application, the solid-liquid separation is carried out by filtration;The rare earth grade of the secondary rare earth concentrate obtained after the solid-liquid separation is REO content > 68%, CaO content < 2%, and rare earth recovery rate > 99%.
[0030] As an optional embodiment of the present application, the solution obtained after the solid-liquid separation contains calcium chloride, calcium phosphate, ferric chloride and rare earth phosphate.
[0031] As an optional embodiment of the present application, the solution obtained after the solid-liquid separation is extracted by N235 to obtain a solution after iron removal.
[0032] In the present application, N235 is used to extract iron, because under certain conditions, iron ions in the solution can form negatively charged complex anions (such as FeCl4 - ) with chloride ions. The nitrogen atom in the N235 molecule has a lone pair of electrons, which can form a stable coordination bond with hydrogen ions (H + ) to generate the corresponding amine salt, and the anion in the amine salt can displace the complex anion formed by the iron ions, so that the iron ions enter the organic phase, thereby realizing separation from the rare earth phosphate solution. The rare earth ions in the rare earth phosphate solution are not easily extracted by N235 under this condition, so they are retained in the aqueous phase.
[0033] Diluent is usually used in the extraction system, and commonly used are sulfonated kerosene, No. 5 solvent oil, etc.
[0034] As an optional embodiment of the present application, calcium salt in the solution is precipitated by adding dilute sulfuric acid to the solution after iron removal, and after solid-liquid separation, calcium sulfate precipitate and waste acid solution containing rare earth phosphate are obtained, and the waste acid solution containing rare earth phosphate is used as a substitute for the low concentration acid or rare earth is recovered from it by extraction, chemical precipitation or ion exchange.
[0035] The waste acid solution obtained by dissolving the rare earth phosphate in the waste acid obtained by adding dilute sulfuric acid to the solution after removing iron to form calcium sulfate precipitation and then performing solid-liquid separation can be reused for the reaction with the original rare earth concentrate (REO>50%) to reduce the consumption of acid. If the acidity of the reused waste acid does not meet the requirements, hydrochloric acid and phosphoric acid can be added to adjust the acidity to the range of the present application. The waste acid reused for multiple times is rich in rare earth phosphate, and the rare earth can be recovered from the rare earth phosphate solution by solvent extraction, chemical precipitation or ion exchange method, so as to reduce the loss of rare earth and further improve the recovery rate of rare earth.
[0036] As an optional embodiment of the present application, the mass percentage content of impurity fluorite in the original rare earth concentrate is 2.5%-3.5%.
[0037] The present application will be further described in detail in combination with specific examples and comparative examples.
[0038] Example 1 ①560 milliliters of dilute hydrochloric acid with a concentration of 4 mol / L and 140 milliliters of dilute phosphoric acid with a concentration of 3 mol / L were added to a reaction kettle, and the volume ratio of dilute hydrochloric acid to dilute phosphoric acid was 4:1.
[0039] ②500 grams of original rare earth concentrate (Baotou mixed rare earth concentrate containing phosphocerite and fluorcarbonate cerite, the ratio of phosphocerite to fluorcarbonate cerite ranges from 1:3 to 1:8, and the mass percentage content of fluorite is about 3%) with a particle size of less than or equal to 200 mesh and an REO content of 51% were added to the reaction kettle, and the mass ratio of acid to ore was 1.5:1. The temperature was raised to 120°C, and the temperature and pressure were maintained for 3 hours under a pressure of 0.2 MPa. After the temperature maintenance was completed, the heating was stopped, and the temperature was cooled to below 80°C.
[0040] ③The solution obtained in the above reaction kettle was filtered by a vacuum filter to obtain 370 grams of secondary rare earth concentrate and 700 milliliters of filtrate.
[0041] ④350 milliliters of mixed solution containing 15% N235 (brand: Aladdin) and 85% No. 5 solvent oil (Shandong Qilin Chemical Co., Ltd.) were added to the above filtrate to extract iron.
[0042] ⑤The extraction liquid in ④ was removed to obtain 700 milliliters of acidic solution, and 4 mol / L dilute sulfuric acid solution was added to precipitate calcium in the solution to obtain calcium sulfate precipitation and acidic filtrate. ⑥The acidic filtrate obtained by solid-liquid separation in step ⑤ was dissolved with rare earth phosphate, which was reused as a substitute for dilute hydrochloric acid and dilute phosphoric acid to react with rare earth concentrate (REO 51%) to reduce the amount of acid used. The waste acid reused for multiple times is rich in rare earth phosphate, and the rare earth can be recovered from the waste acid by solvent extraction, so as to further improve the recovery rate of rare earth.
[0043] Example 2 ①In the reaction kettle, 560 milliliters of dilute hydrochloric acid with a concentration of 8 mol / L and 140 milliliters of 5 mol / L phosphoric acid were added, and the volume ratio of dilute hydrochloric acid to dilute phosphoric acid was 4:1.
[0044] ②500 grams of rare earth concentrate (Baiyunebo mixed rare earth concentrate, containing phosphocerite and fluorcarbonate cerite, the ratio of phosphocerite to fluorcarbonate cerite ranges from 1:3 to 1:8, and the mass percentage content of fluorite is about 3%) with a particle size of less than or equal to 200 mesh and a REO of 51% were added to the reaction kettle, and the mass ratio of acid to ore was 1.5:1. The temperature was raised to 120°C, and the temperature was maintained for 3 hours under a pressure of 0.2 Mpa. After the temperature maintenance was completed, the heating was stopped, and the temperature was cooled to below 80°C.
[0045] ③The solution obtained in the above reaction kettle was filtered by a vacuum filter, and 371 grams of secondary rare earth concentrate and 705 milliliters of filtrate were obtained.
[0046] ④150 milliliters of a mixed solution containing 15 vol% N235 and 85 vol% No. 5 solvent oil were added to the above filtrate to remove iron by extraction.
[0047] ⑤The extraction liquid in ④ was removed to obtain 705 milliliters of an acidic solution, and 8 mol / L dilute sulfuric acid solution was added to precipitate calcium in the solution to obtain calcium sulfate precipitate and acidic filtrate. ⑥The acidic filtrate obtained by solid-liquid separation in step ⑤ contains rare earth phosphate, which can be used as a substitute for dilute hydrochloric acid and dilute phosphoric acid to react with rare earth concentrate (REO 51%) to reduce the amount of acid used. The waste acid rich in rare earth phosphate after multiple uses can be recovered from the waste acid by solvent extraction to further improve the recovery rate of rare earth.
[0048] Example 3 The difference between this example and Example 2 is only that the mass ratio of acid to ore in step ② is 2:1, and the amount of mixed acid is increased in proportion to the amount of rare earth concentrate, which remains the same as in Example 2.
[0049] Comparative Example 1 The difference between this comparative example and Example 1 is only that in step ①, 3 mol / L dilute hydrochloric acid and 2 mol / L dilute phosphoric acid are added to the reaction kettle, and the volume of dilute hydrochloric acid and dilute phosphoric acid remains unchanged.
[0050] Comparative Example 2 The difference between this comparative example and Example 1 is only that in step ①, 10 mol / L dilute hydrochloric acid and 8 mol / L phosphoric acid are added to the reaction kettle, and the volume of dilute hydrochloric acid and dilute phosphoric acid remains unchanged.
[0051] Comparative Example 3 The difference between the present comparative example and Example 1 is only that the mass ratio of acid ore to concentrate in step 2 is 1:1, and the amount of rare earth concentrate is kept consistent with Example 1, and the amount of mixed acid is reduced in proportion.
[0052] Comparative Example 4 The difference between the present comparative example and Example 1 is only that the mass ratio of acid ore to concentrate in step 2 is 3:1, and the amount of rare earth concentrate is kept consistent with Example 1, and the amount of mixed acid is increased in proportion.
[0053] Comparative Example 5 The difference between the present comparative example and Example 1 is only that in step 1, 700 milliliters of dilute hydrochloric acid with a concentration of 4 mol / L is added to the reaction kettle, and no dilute phosphoric acid is added.
[0054] The performance test methods refer to the following standards: Rare earth concentrate grade REO detection method: GB / T 18114.1-2010; Secondary rare earth concentrate CaO content detection method: GB / T 18114.3-2010.
[0055] The primary rare earth concentrate REO, secondary rare earth concentrate REO, secondary rare earth concentrate CaO, and rare earth recovery rate in Examples 1-3 and Comparative Examples 1-5 are detected using the above performance test methods, and the detection data are shown in Table 1. The following data are the average values of repeated detection data of multiple samples.
[0056] Table 1
[0057] Based on the data in the above table, it can be seen that the addition of phosphoric acid can effectively reduce the loss of rare earths. Within the parameter range of the present application, the rare earth concentrate grade can be stabilized to greater than 68%, the rare earth recovery rate can be greater than 99%, and the calcium content can be less than 1%. In Comparative Example 1, the concentrations of hydrochloric acid and phosphoric acid are low, and the secondary rare earth concentrate REO value is lower than that of Example 1. In Comparative Example 2, the concentrations of hydrochloric acid and phosphoric acid used are greater than those of Example 1, and the secondary rare earth concentrate REO is greater than that of Example 1, but it is easy to cause excessive use of acid, and the acid concentration is increased, and the subsequent rare earth dissolution loss causes the rare earth recovery rate to be lower than that of Example 1. In Comparative Example 3, the acid ore ratio is less than that of Example 1, and the secondary rare earth concentrate REO and the rare earth recovery rate are both less than those of Example 1, and the secondary rare earth concentrate CaO is greater than that of Example 1. In Comparative Example 4, the acid ore ratio is greater than that of Example 1, and the secondary rare earth concentrate REO is greater than that of Example 1, and the rare earth recovery rate is less than that of Example 1, which is due to the increase in the proportion of soluble rare earths, resulting in a decrease in the rare earth recovery rate. In Comparative Example 5, no phosphoric acid is used, and the secondary rare earth concentrate REO and the rare earth recovery rate are both less than those of Example 1, indicating that the addition of phosphoric acid can reduce the loss of rare earths.
[0058] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for reducing impurities in rare earth concentrate, characterized in that, The original rare earth concentrate contains one or two minerals from cerium lanthanum phosphate and bastnaesite, and the rare earth grade in the original rare earth concentrate is REO content > 50%; the method includes: adding a low-concentration acid and the original rare earth concentrate to a reaction vessel, heating and maintaining the temperature and pressure for a period of time, then cooling, and then performing solid-liquid separation to obtain a high-purity secondary rare earth concentrate; the low-concentration acid is a mixture of low-concentration hydrochloric acid and low-concentration phosphoric acid; the concentration of the low-concentration hydrochloric acid is 4 mol / L-8 mol / L; the concentration of the low-concentration phosphoric acid is 3 mol / L-5 mol / L.
2. The method for reducing impurities in rare earth concentrate according to claim 1, characterized in that, The volume ratio of low-concentration hydrochloric acid to low-concentration phosphoric acid in the mixed acid is 3:1-5:
1.
3. The method for reducing impurities in rare earth concentrate according to claim 1, characterized in that, The original rare earth concentrate is finely ground rare earth concentrate with a particle size of less than or equal to 200 mesh. And / or, the mass ratio of the added low-concentration acid to the original rare earth concentrate is 1.5:1-2:
1.
4. The method for reducing impurities in rare earth concentrate according to claim 1, characterized in that, The heating and holding process involves heating to 120℃-160℃ and holding at that temperature; and / or, the holding and pressure holding time is 2h-4h; and / or, the pressure holding pressure is 0.1-0.3MPa; and / or, the cooling temperature is cooled to less than 80℃.
5. The method for reducing impurities in rare earth concentrate according to claim 1, characterized in that, The solid-liquid separation is carried out by filtration; the rare earth grade of the secondary rare earth concentrate obtained after solid-liquid separation is REO content > 68%, CaO content < 2%, and rare earth recovery rate > 99%.
6. The method for reducing impurities in rare earth concentrate according to claim 1, characterized in that, The solution obtained after solid-liquid separation contains calcium chloride, calcium phosphate, ferric chloride, and rare earth phosphates.
7. The method for reducing impurities in rare earth concentrate according to claim 6, characterized in that, The solution obtained after solid-liquid separation is subjected to N235 extraction to remove iron, resulting in an iron-free solution.
8. The method for reducing impurities in rare earth concentrate according to claim 7, characterized in that, The solution after iron removal is added with dilute sulfuric acid to precipitate calcium salts in the solution. After solid-liquid separation, calcium sulfate precipitate and waste acid solution containing rare earth phosphates are obtained. The waste acid solution containing rare earth phosphates can be used as a substitute for the low-concentration acid or the rare earths can be recovered from it by solvent extraction, chemical precipitation or ion exchange.
9. The method for reducing impurities in rare earth concentrate according to claim 1, characterized in that, The original rare earth concentrate contains 2.5%-3.5% fluorite by mass percentage.