Composite fluorine removal agent and fluorine reduction method of composite fluorine removal agent in ionic rare earth concentrate

Abstract

The invention relates to the technical field of rare earth impurity removal, in particular to a composite fluorine removal agent and a fluorine reduction method of the composite fluorine removal agent in ionic rare earth concentrate, and the composite fluorine removal agent comprises the following components in percentage by weight: 15-25% of ferric salt, 20-35% of calcium salt, 20-30% of sodium salt, 15-20% of lanthanum compound and 15-20% of cerium compound. According to the method, the iron salt, the calcium salt, the sodium salt, the lanthanum compound and the cerium compound have a synergistic effect, so that the defluorination efficiency can be remarkably improved, the generation of three-phase substances in the subsequent extraction and separation process is reduced, efficient defluorination can be directly realized in an acid-soluble system, and the energy consumption and the production cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of rare earth impurity removal technology, specifically to a composite defluorinating agent and its method for reducing fluoride in ionic rare earth concentrates. Background Technology

[0002] Rare earth elements are indispensable strategic resources in modern industrial systems, widely used in petrochemicals, high-performance materials, metallurgy, electronics, glass and ceramics, and nuclear technology. Among them, ion-adsorption rare earth resources occupy an important position in my country's rare earth industry due to their unique occurrence, stable grade, and concentrated distribution. Ion-adsorption rare earths mainly refer to rare earth ions that exist in an exchangeable state and are adsorbed by clay minerals such as kaolinite and illite. These rare earths can be leached under mild conditions through ion exchange, thus possessing advantages such as simple mining conditions and environmental friendliness, making them an important rare earth mineral that is currently widely mined and utilized in my country.

[0003] In the ammonium sulfate leaching process commonly used for ion-adsorption rare earth ores, the leachate contains not only the target rare earth ions but also a large number of associated impurity ions, among which fluoride ions are particularly prominent. Fluoride originates from trace amounts of fluoride in the ore or fluoride bound to clay minerals, and easily enters the liquid phase when the ore is subjected to acidic or saline leaching. Fluoride ions are significantly detrimental in subsequent extraction and separation processes. They may form stable complexes or products with rare earth elements or extractants, leading to the formation of a three-phase system that makes it difficult to separate the organic and aqueous phases properly, thus affecting extraction efficiency and even forcing the production unit to shut down. Furthermore, high fluoride content also affects the purity of the final rare earth product, which is detrimental to meeting the quality requirements of high-end applications.

[0004] Existing defluorination technologies involve long processes and numerous steps, requiring additional calcination and secondary acid dissolution operations, resulting in high energy consumption and costs, making it difficult to meet the current demand for green and efficient rare earth processing. Summary of the Invention

[0005] (a) Purpose of the invention The purpose of this invention is to provide a composite defluorinating agent and its defluorination method in ionic rare earth concentrates. Through the synergistic effect among the components of iron salt, calcium salt, sodium salt, and lanthanum and cerium compounds, the defluorination efficiency of the composite defluorinating agent can be significantly improved, the generation of three phases in the subsequent extraction and separation process can be reduced, and efficient defluorination can be directly achieved in acid-soluble systems, thereby reducing energy consumption and production costs.

[0006] (II) Technical Solution To address the above problems, the present invention provides a composite defluorinating agent, wherein the components of the composite defluorinating agent, by weight percentage, include: 15-25% iron salt, 20-35% calcium salt, 20-30% sodium salt, 15-20% lanthanum compound, and 15-20% cerium compound.

[0007] In another aspect of the present invention, preferably, the components of the composite defluorinating agent, by weight percentage, include: 16-21% iron salt, 25-30% calcium salt, 21-27% sodium salt, 16-18% lanthanum compound and 16-18% cerium compound.

[0008] In another aspect of the present invention, preferably, The iron salt is at least one of ferrous chloride, ferrous sulfate, polyferrous chloride, and polyferrous sulfate; The calcium salt is at least one of calcium carbonate, calcium chloride, calcium hydroxide, and calcium oxide; The sodium salt is at least one of sodium carbonate, sodium chloride, and sodium hydroxide; The lanthanum compound is at least one of lanthanum oxide, lanthanum hydroxide, and lanthanum carbonate; The cerium compound is at least one of cerium oxide, cerium hydroxide, and cerium carbonate.

[0009] In another aspect of the present invention, preferably, a method for reducing fluoride in ionic rare earth concentrate using a composite defluorinating agent, the method comprising using the composite defluorinating agent as described above to reduce fluoride in the ionic rare earth concentrate, the ionic rare earth concentrate comprising rare earth carbonates and / or rare earth oxides.

[0010] In another aspect, preferably, the invention includes: Hydrochloric acid solution is added to ion-type rare earth concentrate slurry for dissolution to obtain a first mixed liquid; the mass ratio of REO to hydrochloric acid solution in the ion-type rare earth concentrate slurry is a preset first ratio; The first mixture is subjected to a first heating treatment to obtain a second mixture. A composite defluorinating agent is added to the second mixture to obtain a third mixture; the mass ratio of fluorine to the composite defluorinating agent in the second mixture is a preset second ratio. The third mixture is subjected to a second heat treatment to obtain a fourth mixture. The fourth mixture is subjected to impurity removal treatment to obtain a rare earth solution with reduced fluoride content.

[0011] In another aspect of the present invention, preferably, the ionic rare earth concentrate slurry comprises ionic rare earth concentrate slurry and water, wherein the mass ratio of the ionic rare earth concentrate slurry to water is 1:1 to 1:2. The REO content of the ion-type rare earth concentrate slurry is 500g / L~1000g / L; The concentration of the hydrochloric acid solution is 8 mol / L to 10 mol / L; The preset first ratio is 1:1.5 to 1:2.0; The pH value of the first mixture is 0.5 to 1.0.

[0012] In another aspect of the present invention, preferably, the temperature of the first heat treatment is 90°C to 95°C.

[0013] In another aspect of the present invention, preferably, the preset second ratio includes a mass ratio of ionic rare earth concentrate fluorine to composite defluorinating agent of 1:2 to 1:6.

[0014] In another aspect of the present invention, preferably, the temperature of the second heat treatment is 90°C to 95°C, and the time of the first heat treatment is 1 hour to 2 hours.

[0015] In another aspect of the present invention, preferably, the purification treatment of the fourth mixed solution to obtain the defluorinated rare earth solution includes: Add barium chloride solution to the fourth mixture, and perform solid-liquid separation to obtain the fifth mixture; Adjust the pH of the fifth mixture to 4.5-5.0 to obtain the sixth mixture; A flocculant is added to the sixth mixture, and solid-liquid separation is performed to obtain a rare earth solution after fluoride reduction.

[0016] (III) Beneficial Effects The above-described technical solution of the present invention has the following beneficial technical effects: The composite defluorinating agent of the present invention is composed of iron salt, calcium salt, sodium salt, and lanthanum and cerium compounds in a specific ratio. The components form a synergistic effect, which can significantly improve the defluorination efficiency, effectively reduce the fluorine content in rare earth feed solution, reduce the generation of three phases in the subsequent extraction and separation process, improve phase separation performance, and improve the stability of rare earth extraction process.

[0017] Meanwhile, this invention eliminates the need for complex steps such as oxalic acid precipitation, ignition, and secondary acid dissolution, and can directly achieve efficient defluorination in the acid dissolution system, reducing energy consumption and production costs, and has good industrial application value. Attached Figure Description

[0018] Figure 1 This is an overall flowchart of one embodiment of the present invention; Figure 2 This is a schematic diagram of the overall process of one embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0020] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Example A composite defluorinating agent, comprising, by weight percentage: 15-25% iron salt, 20-35% calcium salt, 20-30% sodium salt, 15-20% lanthanum compound, and 15-20% cerium compound. Each component can exert a synergistic effect of precipitation, adsorption, and complexation to capture fluoride in an acidic solution system, thereby achieving efficient removal of fluoride ions from rare earth acid-soluble solutions. The higher dosage of calcium and sodium salts is primarily used to react with free fluoride ions in the solution to generate stable precipitates such as calcium fluoride and sodium hexafluoroaluminate, and also to regulate the pH and partially neutralize the acidity of the solution, thus ensuring the continuity of the defluorination process and the stability of the precipitation system. The relatively lower dosage of iron salt and lanthanum and cerium compounds is based on the limited free fluoride content in the rare earth acid-soluble system; only a small amount is needed for effective adsorption and complexation capture through hydrolysis products or the hydroxyl groups on the surface of rare earth hydroxides. Excessive iron salts significantly increase the iron impurity content in the system, which is detrimental to subsequent purification. While lanthanum and cerium compounds can further enhance adsorption performance, excessive use will lead to a waste of rare earth resources and significantly increase costs. Therefore, this formulation comprehensively considers precipitation efficiency, adsorption capacity, system impurity control, and economics, achieving an optimal balance between defluorination efficiency and process cost.

[0024] Furthermore, in this embodiment, the components of the composite defluorinating agent, by weight percentage, include: 16-21% iron salt, 25-30% calcium salt, 21-27% sodium salt, 16-18% lanthanum compound, and 16-18% cerium compound. This can improve precipitation rate and settling performance while ensuring defluorination efficiency, reduce colloidal intermediates generated during the defluorination process, and improve the efficiency and stability of solid-liquid separation.

[0025] Furthermore, in this embodiment, the iron salt is at least one of ferrous chloride, ferrous sulfate, polyferrous chloride, and polyferrous sulfate; the iron salt can be hydrolyzed under acidic conditions to generate iron oxides or hydroxyl complexes, which have good adsorption and co-precipitation effects on fluoride ions, and can also remove impurities such as silicon and phosphorus from the feed liquid, thereby improving the system's purification capacity.

[0026] The calcium salt is at least one of calcium carbonate, calcium chloride, calcium hydroxide, and calcium oxide. The calcium salt reacts with fluoride ions to form calcium fluoride precipitate, and its poor solubility ensures the stability of efficient fluoride ion removal. Different calcium salt forms can be flexibly selected according to the acidity of the feed solution to control the precipitation rate and adaptability.

[0027] The sodium salt is at least one of sodium carbonate, sodium chloride, and sodium hydroxide. The main function of the sodium salt is to adjust the ionic strength of the system, promote the formation of crystal nuclei during the precipitation process, make the fluoride precipitate grow and settle more easily, and thus improve the efficiency of solid-liquid separation.

[0028] The lanthanum compound is at least one selected from lanthanum oxide, lanthanum hydroxide, and lanthanum carbonate; the cerium compound is at least one selected from cerium oxide, cerium hydroxide, and cerium carbonate. Lanthanum and cerium have a high stable binding ability with fluoride ions and can form insoluble rare earth fluorides with fluoride ions in acid-soluble systems, thereby further capturing residual fluoride. Their addition endows the defluorinating agent with deep defluorination capabilities, which can significantly reduce the final residual amount of fluoride in the system, and is particularly suitable for the treatment of ion-adsorption rare earth concentrates.

[0029] This embodiment also provides a method for reducing fluoride in ionic rare earth concentrate using a composite defluorinating agent. The method includes using the composite defluorinating agent as described above to reduce fluoride in the ionic rare earth concentrate, wherein the ionic rare earth concentrate includes rare earth carbonates and / or rare earth oxides. Figure 1 An overall flowchart of one embodiment of the present invention is shown, as follows: Figure 1 As shown, the methods for reducing fluoride content include: Hydrochloric acid solution is added to the ionic rare earth concentrate slurry according to the preset first ratio to dissolve it and obtain the first mixed liquid. This process is the acid dissolution process. The ionic rare earth concentrate and water are made into an ionic rare earth concentrate slurry. The mass ratio of the ionic rare earth concentrate slurry and water is 1:1 to 1:2, so that the rare earth ore powder can be fully wetted before the acid is added and form a slurry system with good fluidity. This mass ratio can ensure that the slurry has a suitable viscosity and stirability, which is conducive to the full contact and uniform mixing of each component in the subsequent acid dissolution reaction. The REO content of the ion-modified rare earth concentrate slurry is 500g / L~1000g / L. REO represents the rare earth concentration, ensuring a moderate rare earth content in the slurry. This facilitates the smooth progress of the dissolution reaction and promotes the full release of fluoride ions into the liquid phase. Maintaining a certain slurry concentration ensures the reaction proceeds fully, preventing the slurry from clumping to the bottom and ensuring sufficient ionic activity for the subsequently added hydrochloric acid. The hydrochloric acid solution concentration is 8mol / L~10mol / L. The preset first ratio includes a mass ratio of ion-modified rare earth concentrate REO to hydrochloric acid solution of 1:1.5~1:2.0. The pH value of the first mixed solution is 0.5~1.0. This ensures that the amount of hydrochloric acid is sufficient to completely dissolve the rare earth oxides or rare earth carbonates in the system, while providing a sufficient acidic environment for associated components such as fluorine, aluminum, and iron to migrate into the liquid phase. This avoids problems such as incomplete dissolution, reaction residues, or incomplete fluoride entry into the liquid phase due to insufficient acid. Hydrochloric acid solution can be added gradually under stirring to avoid excessive local acid concentration, which could lead to splashing or uneven reaction.

[0030] After hydrochloric acid is added and the reaction is complete, a first mixed solution is obtained, the pH of which is controlled within the range of 0.5 to 1.0. This pH range ensures that rare earth elements exist entirely in the form of soluble chlorides, allowing fluoride ions in the system to be released into the solution. This is beneficial for improving the reaction efficiency of subsequent defluorinating agents and provides an ideal acidic environment for fluoride to precipitate, adsorb, or co-precipitate.

[0031] The first mixed liquid is subjected to a first heat treatment to obtain a second mixed liquid. The temperature of the first heat treatment is 90℃~95℃, and the degree of the first heat treatment is such that the liquid becomes clear. In this embodiment, the first heat treatment is carried out using a fiberglass reactor. The fiberglass reactor is acid-resistant and high-temperature resistant, and equipped with an electric heating function, which can maximize the reaction requirements. The first heat treatment can promote the further dissolution of ion-type rare earth concentrate and the full reaction of impurity ions, so that the system reaches a stable chemical equilibrium state. The temperature of the first heat treatment reaches the pre-boiling state. Under this condition, the reaction proceeds fully, the acid dissolution effect is optimal, the energy consumption is minimized, the rare earth leaching rate can be significantly improved, and the splashing of the liquid caused by excessive temperature is avoided.

[0032] The composite defluorinating agent is added to the second mixture according to a preset second ratio to obtain the third mixture. The preset second ratio includes a mass ratio of fluorine from ionic rare earth concentrate to the composite defluorinating agent of 1:2 to 1:6. This achieves precipitation, adsorption, and complexation capture of fluoride ions. During the addition process, stirring can be used to ensure uniform dispersion of the composite defluorinating agent in the system, allowing iron salts, calcium salts, sodium salts, and lanthanum and cerium compounds to fully exert their synergistic effect, forming fluoride precipitates or co-precipitates, thereby obtaining the third mixture. The preset second ratio ensures that the dosage of the defluorinating agent matches the fluoride ion concentration in the system, guaranteeing the defluorination effect while avoiding the increase of by-products and subsequent filtration burden caused by excessive addition of the defluorinating agent, thus avoiding agent waste. The preparation of the composite defluorinating agent involves uniformly mixing iron salts, calcium salts, sodium salts, lanthanum compounds, and cerium compounds.

[0033] The third mixture is subjected to a second heat treatment to obtain a fourth mixture. The temperature of the second heat treatment is 90℃~95℃, and the time of the first heat treatment is 1h~2h. This further promotes the formation and crystal growth of fluoride precipitates, thereby improving the removal efficiency of fluoride ions in the system. At this temperature and duration, the reaction between the components of the composite defluorinating agent and fluoride ions is more complete, and the precipitate particles crystallize more completely, which is beneficial to the smooth progress of the subsequent solid-liquid separation process. The second heat treatment process can be carried out in a fiberglass reaction vessel.

[0034] The fourth mixed solution is subjected to impurity removal treatment to obtain a defluorinated rare earth solution. The impurity removal treatment removes any residual sulfate, phosphate, heavy metal ions, and other impurities from the system, ensuring that the subsequent rare earth solution meets the requirements of the purification process. This includes: A barium chloride solution is added to the fourth mixture, and solid-liquid separation is performed to obtain a fifth mixture. Adding another barium chloride solution to the fourth mixture causes the barium chloride to react with sulfate ions in the system to form a sparingly soluble barium sulfate precipitate, effectively removing sulfate ions and related impurities. The amount of barium chloride solution added can be adjusted to the amount of SO4 in the solution. 2- Content, by weight of SO4 2- Ba 2+ =1:1.5, add barium chloride.

[0035] Adjust the pH of the fifth mixture to 4.5-5.0 to obtain the sixth mixture; ammonia water can be used for adjustment and thorough stirring to remove aluminum impurities and promote the formation of some fluoride ions as precipitates.

[0036] A flocculant is added to the sixth mixed liquid, and solid-liquid separation is performed to obtain a defluorinated rare earth liquid. The flocculant here can be PAM. After settling, clarification, filtration, and other production processes, the defluorinated rare earth liquid is produced. The amount of flocculant added can be 3‰ of the amount of rare earth material processed.

[0037] The overall principle is as follows: after adding hydrochloric acid solution, most of the fluorides decompose to release fluoride ions, and the impurity alumina also dissolves. When the ion-type rare earth concentrate slurry is mixed with hydrochloric acid solution at 90~95℃, the following reaction occurs: RE2O3+6HCl→3H2O+2RECl3, CaF2+2HCl→2HF+CaCl2, REFCO3+3HCl→RECl3+CO2↑+HF+H2O, Al2O3+6HCl→3H2O+2AlCl3 In the first mixed solution, fluoride ions form fluoride precipitates, and a small amount of rare earth elements react with fluoride ions to form rare earth fluoride precipitates, resulting in a small loss of rare earth elements. The following reactions occur: RECl3 + 3HF → REF3↓ + 3HCl When the composite defluorinating agent is added and mixed thoroughly, it dissolves and fluoride ions react with the composite defluorinating agent to form fluoride precipitates. The fluoride ions react with the composite defluorinating agent in the following way: Na2CO3+2HCl→2NaCl+H2O+CO2↑ or NaOH+HCl→NaCl+H2O, Ca(OH)2+2HF→CaF2↓+2H2O After adjusting the pH, some fluoride ions precipitate, and aluminum hydroxide reacts with fluoride ions to form sodium hexafluoroaluminate precipitate, as shown in the following reaction: Al(OH)3+3H + +3Na + +6F - →Na3AlF6↓+3H2O The ferrous salt in the composite defluorinating agent can hydrolyze to produce ferrous hydroxide and hydrogen ions. The ferrous hydroxide is further oxidized to ferric hydroxide, removing fluoride ions through adsorption and precipitation. The composite defluorinating agent also contains oxides or hydroxides of lanthanum and cerium, which have strong selectivity for fluoride ions. According to the hard-soft acid-base (HEAB) theory, rare earth ions such as lanthanum and cerium ions (most commonly La) are more selective for fluoride ions. 3+ or Ce 4+ It is characterized by its small size, high oxidation state and weak polarization. It belongs to hard acid and is very easy to combine with hard bases such as fluoride ions. Its adsorption mechanism is mainly that rare earth ions combine with fluoride ions to form stable complexes.

[0038] After the above reaction, the rare earth solution after fluoride removal is F. -Rare earth feed solution with concentration ≤50mg / L and REO = 1.2~1.5mol / L is sent to the extraction process for continued production; the impurity acid residue is sent to the slag storage for further processing.

[0039] Figure 2 A schematic diagram of the overall process of an embodiment of the present invention is shown, as follows: Figure 2 The method for reducing fluoride content is described in detail below: First, at 15m 3 The fiberglass reactor is used to prepare an ionic rare earth concentrate slurry with a concentration of 500 g / L to 1000 g / L by adding water at a solid-liquid weight ratio of 1:1 to 1:2. An 8 mol / L to 10 mol / L hydrochloric acid solution is added to the rare earth concentrate slurry, with the REO content of the ionic rare earth concentrate and the solid-liquid mass ratio of the hydrochloric acid being 1:1.5 to 1:2.0. The reaction is heated to an adjustable temperature of 90℃ to 95℃. A composite defluorinating agent is added in the same 15m... 3 In a fiberglass reactor, the reaction is carried out at 90℃~95℃ for 1~2 hours. Barium chloride is then added to remove sulfate ions. Ammonia water is used to adjust the pH of the solution to 4.5~5.0 to remove some Al. The mixture is thoroughly stirred, then flocculant is added, allowed to stand and clarify, and filtered to obtain F. - Rare earth feed solutions with concentrations ≤50 mg / L and REO = 1.2~1.5 mol / L are sent to the extraction process for continued production; the impurity-removed acid residue is sent to the slag storage for further processing.

[0040] For ease of understanding, the above process can be simplified as follows: Ionic rare earth concentrate (carbonate or oxide concentrate) with a fluoride content of 0.2-0.6% → mixed with water (solid-liquid weight ratio) at a ratio of 1:1-1:2 → added with 8 mol / L-10 mol / L hydrochloric acid at a ratio of 1:1.5-1:2.0 → acid dissolved at 90-95℃ → added with a composite defluorinating agent at a ratio of 1:2-1:6 → stirred thoroughly for 1-2 hours → added barium chloride to remove sulfate ions → adjusted the feed solution to pH 4.5-5.0 with ammonia water → stirred thoroughly → added flocculant → allowed to stand and clarify → filtered → F obtained. - Rare earth feed solutions with concentrations ≤50 mg / L and REO = 1.2~1.5 mol / L are sent to the extraction process for continued production; the impurity-removed acid residue is sent to the slag storage for further processing.

[0041] This invention eliminates the need for complex steps such as oxalic acid precipitation, calcination, and secondary acid dissolution, and can directly achieve efficient defluorination in the acid dissolution system, reducing energy consumption and production costs, and has good industrial application value.

[0042] Example 1 The fluorine content is 0.39% (F -Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:2) → mixed with water to form a slurry → 10 mol / L hydrochloric acid added at a first ratio of 1:1.5 → first heating treatment temperature 92℃ → addition of composite defluorinating agent (composite components are as follows: 15% ferrous chloride, 30% calcium carbonate, 20% sodium carbonate, 20% lanthanum oxide and 15% cerium oxide) at a preset second ratio of 1:2 → second heating treatment temperature 92℃, reaction for 1 h → barium chloride to remove sulfate → ammonia water to adjust the feed solution to pH=4.7 → thorough stirring → addition of flocculant → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =38mg / L, REO=1.2mol / L).

[0043] Example 2 The fluorine content is 0.20% (F - Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:1) → mixed with water to form a slurry → 9 mol / L hydrochloric acid added at a first ratio of 1:1.6 → first heating treatment temperature 90℃ → addition of composite defluorinating agent (composite components are as follows: ferrous sulfate 25%, calcium chloride 20%, sodium chloride 25%, lanthanum hydroxide 15%, and cerium hydroxide 15%) at a preset second ratio of 1:3 → second heating treatment temperature 90℃, reaction for 1.5h → barium chloride to remove sulfate ions → ammonia water to adjust the feed solution to pH=4.9 → thorough stirring → addition of flocculant → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =50mg / L, REO=1.3mol / L).

[0044] Example 3 The fluorine content is 0.45% (F - Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:2) → mixed with water to form a slurry → 10 mol / L hydrochloric acid added at a first ratio of 1:1.7 → first heating treatment temperature 95℃ → composite defluorinating agent added (composite defluorinating agent components are as follows: 18% polyferrous chloride, 25% calcium hydroxide, 22% sodium hydroxide, 18% lanthanum carbonate and 17% cerium carbonate) at a preset second ratio of 1:4 → second heating treatment temperature 95℃, reaction for 2 hours → barium chloride to remove sulfate → ammonia water to adjust the feed solution to pH=4.5 → thorough stirring → flocculant added → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =17mg / L, REO=1.5mol / L).

[0045] Example 4 The fluorine content is 0.60% (F -Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:1) → mixed with water to form a slurry → 8 mol / L hydrochloric acid added at a first ratio of 1:1.8 → first heating treatment temperature 94℃ → addition of composite defluorinating agent (composite components are as follows: 15% polyferrous sulfate, 35% calcium oxide, 20% sodium carbonate, 15% lanthanum oxide and 15% cerium hydroxide) at a preset second ratio of 1:5 → second heating treatment temperature 94℃, reaction for 1 h → barium chloride to remove sulfate ions → ammonia water to adjust the feed solution to pH=5.0 → thorough stirring → addition of flocculant → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =24mg / L, REO=1.4mol / L).

[0046] Example 5 The fluorine content is 0.53% (F - Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:2) → mixed with water to form a slurry → 10 mol / L hydrochloric acid added at a first ratio of 1:1.9 → first heating treatment temperature 91℃ → addition of composite defluorinating agent (composite components are as follows: ferrous chloride 17%, calcium chloride 27%, sodium chloride 22%, lanthanum hydroxide 16%, and cerium carbonate 18%) at a preset second ratio of 1:6 → second heating treatment temperature 91℃, reaction for 1.5 h → barium chloride to remove sulfate → ammonia water to adjust the feed solution to pH=4.6 → thorough stirring → addition of flocculant → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =22mg / L, REO=1.3mol / L).

[0047] Example 6 The fluorine content is 0.24% (F - Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:2) → mixed with water to form a slurry → 9 mol / L hydrochloric acid added at a first ratio of 1:2.0 → first heating treatment temperature 93℃ → composite defluorinating agent added (composite defluorinating agent components are as follows: ferrous sulfate 16%, calcium hydroxide 28%, sodium hydroxide 22%, lanthanum carbonate 17%, and cerium oxide 17%) at a preset second ratio of 1:4.5 → second heating treatment temperature 93℃, reacted for 2 hours → barium chloride to remove sulfate ions → ammonia water adjusted to pH=4.8 → thorough stirring → flocculant added → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =13mg / L, REO=1.2mol / L).

[0048] Example 7 The fluorine content is 0.36% (F -Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:1) → mixed with water to form a slurry → 8 mol / L hydrochloric acid added at a first ratio of 1:1.6 → first heating treatment temperature 95℃ → composite defluorinating agent added (composite defluorinating agent components are as follows: 20% polyferrous chloride, 27% calcium carbonate, 21% sodium carbonate, 17% lanthanum hydroxide and 15% cerium oxide) at a preset second ratio of 1:5.5 → second heating treatment temperature 95℃, reacted for 1 hour → barium chloride to remove sulfate ions → ammonia water adjusted to pH=4.5 → thorough stirring → flocculant added → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =43mg / L, REO=1.4mol / L).

[0049] Example 8 The fluorine content is 0.57% (F - Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:2) → mixed with water to form a slurry → 10 mol / L hydrochloric acid added at a first ratio of 1:1.7 → first heating treatment temperature 92℃ → composite defluorinating agent added (composite defluorinating agent components are as follows: 15% polyferrous sulfate, 31% calcium hydroxide, 23% sodium chloride, 15% lanthanum oxide and 16% cerium carbonate) at a preset second ratio of 1:6 → second heating treatment temperature 92℃, reaction for 1.5 h → barium chloride to remove sulfate ions → ammonia water adjusted to pH=5.0 → thorough stirring → flocculant added → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =35mg / L, REO=1.5mol / L).

[0050] Example 9 The fluorine content is 0.48% (F - Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:2) → mixed with water to form a slurry → 9 mol / L hydrochloric acid added at a first ratio of 1:1.8 → first heating treatment temperature 90℃ → addition of composite defluorinating agent (composite components are as follows: ferrous sulfate 21%, calcium oxide 20%, sodium hydroxide 25%, lanthanum carbonate 17%, and cerium oxide 17%) at a preset second ratio of 1:5 → second heating treatment temperature 90℃, reaction for 2 hours → barium chloride to remove sulfate ions → ammonia water to adjust the feed solution to pH=4.7 → thorough stirring → addition of flocculant → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =48mg / L, REO=1.3mol / L).

[0051] Example 10 The fluorine content is 0.28% (F -Ionic rare earth oxide concentrate (solid-liquid weight ratio 1:1) → mixed with water to form a slurry → 8 mol / L hydrochloric acid added at a first ratio of 1:1.6 → first heating treatment temperature 94℃ → composite defluorinating agent added (composite defluorinating agent components are as follows: ferrous chloride 17%, calcium carbonate 23%, sodium carbonate 27%, lanthanum carbonate 15%, and cerium hydroxide 18%) at a preset second ratio of 1:3.5 → second heating treatment temperature 94℃, reacted for 1 hour → barium chloride to remove sulfate ions → ammonia water adjusted to pH=4.9 → thorough stirring → flocculant added → settling and clarification → filtration → ion-type rare earth concentrate filtrate (F - =31mg / L, REO=1.2mol / L).

[0052] Comparative Example High-fluorine-content ionic rare earth ore → hydrochloric acid dissolution → solid-liquid separation → filtrate with oxalic acid precipitation → oxalic acid rare earth concentrate → calcination → low-fluorine-content oxide rare earth concentrate → hydrochloric acid dissolution → low-fluorine-content acid-soluble solution.

[0053] Table 1 shows the reaction parameters of Examples 1-10, and Table 2 shows the components of the composite defluorinating agent of Examples 1-10; Table 1 Reaction parameters of Examples 1-10 Table 2 Components of the composite defluorinating agent in Examples 1-10 Table 3 Effect parameters of Examples 1-10 and Comparative Examples Table 3 shows the effect parameters of Examples 1-10 and the comparative example. The fluorine content after defluorination in Examples 1-10 is better than that in the comparative example, and the cost of Examples 1-10 is significantly lower than that in the comparative example.

[0054] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

[0055] The present invention has been described above with reference to embodiments thereof. However, these embodiments are merely illustrative and not intended to limit the scope of the invention. The scope of the invention is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of the invention, and all such substitutions and modifications should fall within the scope of the invention.

[0056] Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and modifications can be made to the embodiments of the present invention without departing from the spirit and scope of the invention.

[0057] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite defluorinating agent, characterized in that, The components of the composite fluoride removal agent include, by weight percentage, 15-25% of iron salt, 20-35% of calcium salt, 20-30% of sodium salt, 15-20% of lanthanum compound, and 15-20% of cerium compound.

2. The composite fluorine removing agent according to claim 1, wherein The components of the composite fluoride removal agent include, by weight percentage, 16-21% of iron salt, 25-30% of calcium salt, 21-27% of sodium salt, 16-18% of lanthanum compound, and 16-18% of cerium compound.

3. The composite fluoride removal agent according to claim 1, wherein, the iron salt is at least one of ferrous chloride, ferrous sulfate, polymeric ferrous chloride, and polymeric ferrous sulfate; the calcium salt is at least one of calcium carbonate, calcium chloride, calcium hydroxide, and calcium oxide; the sodium salt is at least one of sodium carbonate, sodium chloride, and sodium hydroxide; the lanthanum compound is at least one of lanthanum oxide, lanthanum hydroxide, and lanthanum carbonate; the cerium compound is at least one of cerium oxide, cerium hydroxide, and cerium carbonate.

4. A method for reducing fluorine in ion-type rare earth concentrate by using a composite fluorine removal agent, characterized in that, The method comprises using the composite fluoride removal agent according to any one of claims 1-3 to reduce the fluorine content of ion-type rare earth concentrate, wherein the ion-type rare earth concentrate comprises rare earth carbonate and / or rare earth oxide.

5. The method of claim 4, wherein the fluorine reduction method is characterized by, The method comprises: adding hydrochloric acid solution to ion-type rare earth concentrate slurry for dissolution to obtain a first mixed liquid; the mass ratio of REO in the ion-type rare earth concentrate slurry to the mass of the hydrochloric acid solution is a preset first ratio; subjecting the first mixed liquid to first heating treatment to obtain a second mixed liquid; adding a composite fluoride removal agent to the second mixed liquid to obtain a third mixed liquid; the mass ratio of fluorine in the second mixed liquid to the composite fluoride removal agent is a preset second ratio; subjecting the third mixed liquid to second heating treatment to obtain a fourth mixed liquid; subjecting the fourth mixed liquid to impurity removal treatment to obtain a rare earth liquid after fluorine reduction.

6. The method of claim 5, wherein the fluorine reduction method is characterized by, The ion-type rare earth concentrate slurry comprises ion-type rare earth concentrate slurry and water, and the mass ratio of the ion-type rare earth concentrate slurry to water is 1:1-1:2; the REO content of the ion-type rare earth concentrate slurry is 500 g / L-1000 g / L; the concentration of the hydrochloric acid solution is 8 mol / L-10 mol / L; the preset first ratio is 1:1.5-1:2.0; the pH value of the first mixed liquid is 0.5-1.

0.

7. The method of claim 5, wherein the step of reducing the amount of fluoride comprises the step of: The temperature of the first heating treatment is 90°C-95°C.

8. The method of claim 5, wherein the fluorine reduction method is characterized by, The preset second ratio is 1:2-1:

6.

9. The method of claim 5, wherein the fluorine reduction method is characterized by, The temperature of the second heating treatment is 90°C-95°C, and the time of the first heating treatment is 1 h-2 h.

10. The method of claim 5, wherein the method further comprises: The impurity removal treatment of the fourth mixed liquid to obtain a rare earth liquid after fluorine reduction comprises: adding barium chloride solution to the fourth mixed liquid, and subjecting the mixture to solid-liquid separation to obtain a fifth mixed liquid; adjusting the pH value of the fifth mixed liquid to 4.5-5.0 to obtain a sixth mixed liquid; adding a flocculating agent to the sixth mixed liquid, and subjecting the mixture to solid-liquid separation to obtain a rare earth liquid after fluorine reduction.

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