Method for efficiently removing fluorine ions in high-chlorine rare earth feed liquid by using rare earth cerium carbonate

Abstract

The invention belongs to the technical field of rare earth wet smelting, and relates to a method for efficiently removing fluorine ions in high-chlorine rare earth feed liquid by using rare earth cerous carbonate, which comprises the following steps of: raising the temperature of the high-chlorine rare earth feed liquid to 40-100 DEG C, regulating the pH value to be lower than 2, adding the rare earth cerous carbonate which accounts for 1-15% of the mass of the rare earth feed liquid, stirring and reacting for 2-4 hours, standing and preserving heat for 0.5-1 hour, and filtering to obtain a filtrate; and finally, adjusting the pH value of the feed liquid to be lower than 4.5, and carrying out solid-liquid separation to complete the purpose of efficiently removing the fluorine ions. According to the method, fluorine ions in perchloric acid rare earth feed liquid are treated by rare earth cerium carbonate, rare earth fluoride precipitates are formed through a chemical reaction to complete efficient removal of fluorine elements in the feed liquid, and the low-fluorination quality requirement of a rare earth smelting and extracting procedure on the rare earth feed liquid and preparation of a high-purity rare earth product are guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth hydrometallurgy, and more specifically relates to a method for efficiently removing fluoride ions in high-chloride rare earth liquid by using rare earth cerium carbonate. Background Art

[0002] High-grade rare earth concentrates containing fluorinated bastnaesite and monazite undergo an oxidation roasting and hydrochloric acid leaching process. While a small amount of F escapes as HF gas during roasting, a significant amount of F enters the acid leaching residue as rare earth fluorides and fluoride oxides. The resulting high-chloride rare earth feed solution, obtained after neutralization of the alkaline cake with the acid leaching solution, still contains extremely high levels of fluoride ions. Consequently, the defluorination of high-chloride rare earth feed solutions presents a significant challenge to manufacturers' production processes. This is primarily because the high fluorine content in the rare earth feed solution directly impacts subsequent extraction steps and also reduces the quality of the resulting rare earth products.

[0003] As we all know, part of the fluoride ions in the high-chloride rare earth solution are slightly soluble in the solution as rare earth fluorides, and the other part of the fluoride ions in the rare earth solution are easily soluble in the solution due to their high electronegativity and small ionic radius. 3+ Coordination formation [REF] 2+ Colloidal particles suspended in the rare earth liquid can easily lead to precipitation of rare earth fluoride if left standing or stirred for a long time. If this part of fluoride ions is not removed and directly enters the extraction process, it will easily emulsify the organic phase in the extraction tank and reduce the grade of the rare earth product.

[0004] Common processes for removing fluoride ions from high-chloride rare earth feed solutions involve adding magnesium or calcium salts to remove and separate fluoride ions through precipitation reactions. However, these processes present difficulties in precipitating, result in significant rare earth losses, and generate fluorine-containing waste gas, leading to numerous environmental issues. Therefore, developing new defluoridation agents for high-chloride rare earth feed solutions is a critical technical challenge that must be addressed in the future rare earth smelting industry. Summary of the Invention

[0005] The embodiment of the present application provides a method for removing fluoride ions from a high-chloride rare earth feed solution using rare earth cerium carbonate as a defluoridating agent, thereby solving the problems of difficult precipitation treatment, large rare earth loss, and fluorine-containing waste gas pollution in the prior art defluoridation process for a high-chloride rare earth feed solution, thereby achieving efficient fluoridation, stable rare earth distribution, precipitation recycling, and clean production.

[0006] In order to solve the above technical problems, the present invention provides a method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth cerium carbonate, comprising the following steps:

[0007] S1. Prepare a high-chloride rare earth solution, the composition of which includes REO 200g / L~400g / L, F 0.1g / L~0.8g / L, CaO 1g / L~5g / L, MgO 1g / L~5g / L, Al2O3 0.1g / L~0.3g / L, BaO 2.0g / L~3.5g / L, and ZnO <0.4g / L;

[0008] S2. Add hydrochloric acid to adjust the pH value of the high-chloride rare earth solution to pH < 2;

[0009] S3, raising the temperature of the acidic high-chloride rare earth liquid to 60°C to 100°C, adding a rare earth cerium carbonate defluoridant and stirring the reaction, the amount of which is 1% to 15% of the mass of the rare earth liquid, and then allowing the mixture to stand and keep warm;

[0010] S4. Add NaOH to adjust the pH value of the rare earth liquid to below 4.5, and then perform solid-liquid separation to obtain a defluorinated rare earth liquid and a precipitated residue. The defluorinated rare earth liquid can directly enter the extraction process, and the precipitated residue is a fluorocarbon rare earth compound, which can be directly returned to the alkaline decomposition process for rare earth recovery.

[0011] As some embodiments of the present application, after adding the rare earth cerium carbonate defluoridation agent, the mixture is stirred and reacted for 2 hours to 4 hours, and then allowed to stand and keep warm for 0.5 hours to 1.5 hours.

[0012] As some embodiments of the present application, the particle size of the rare earth cerium carbonate defluoridating agent is controlled to be 50 μm to 200 μm.

[0013] As some embodiments of the present application, the purity of the rare earth cerium carbonate defluoridating agent is higher than 90%.

[0014] As some embodiments of the present application, the stirring intensity is controlled at 200 r / min to 700 r / min.

[0015] As some embodiments of the present application, the fluorine removal rate of the high-chloride rare earth feed solution exceeds 90%, and the feed solution REO / F concentration ratio exceeds 40,000.

[0016] The thermodynamic principle of the present method is that rare earth carbonate is hydrolyzed into basic rare earth carbonate (RECO3(OH)), which generates CO2 gas. Basic rare earth carbonate has a strong adsorption capacity for fluoride ions. Therefore, when cerium carbonate is added as a defluoridating agent to a high-fluorine, high-chloride rare earth feed solution at temperatures above 40°C, the following reaction is bound to occur:

[0017] Ce2(CO3)3+mF - +(6-2p-q)H + +(p+q-3)H2O=Ce2F m (CO3) p(OH) q +(3-p)CO2↑Ce2(CO3)3+m[REF] 2+ +(6-2p-q)H + +(p+q-3)H2O=(2Ce,mRE)F m (CO3) p (OH) q +(3-p)CO2↑

[0018] At the same time, a polar covalent bond is formed between the fluoride ion and the cerium carbonate, and the fluorine-carbon rare earth compound REFCO3 is generated. Finally, the fluoride ion in the high-chloride rare earth solution is removed in the form of precipitation. The main reactions are as follows:

[0019] mCe2(CO3)3+3nF - =(mCe2)F 3n (CO3) 3m

[0020] mCe2(CO3)3+3n[REF] 2+ =(2mCe,3nRE)F 3n (CO3) 3m

[0021] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0022] (1) Highly efficient fluorine removal without introducing impurity pollution. Rare earth cerium carbonate is used as a defluoridation agent. It reacts with fluoride ions through chemical precipitation and adsorption to form a fluorocarbon rare earth compound. It can effectively remove fluoride ions from high-chloride rare earth feed liquid. The fluorine removal rate exceeds 90%, and the REO / F concentration ratio of the feed liquid after defluoridation exceeds 40,000. Since cerium carbonate and the rare earth elements in the feed liquid are both rare earth compounds, no other foreign impurity ions are introduced after addition, avoiding the impurity pollution problem of traditional magnesium salt / calcium salt processes.

[0023] (2) The raw materials are economical and readily available, and the process cost is low. The cerium content in fluorocarbon cerium ore is as high as 80%, and the raw material source of cerium carbonate is abundant and has long-term overcapacity, resulting in a low cost. Compared with traditional defluoridation agents, this process does not require the introduction of additional high-priced or scarce materials, reducing raw material costs from the source; at the same time, the defluoridation process does not produce difficult-to-treat precipitates or fluorine-containing waste gases, reducing subsequent environmental protection management costs.

[0024] (3) Precipitation recycling achieves a closed-loop resource cycle. The fluorocarbon rare earth compounds generated by the reaction can be directly returned to the alkaline decomposition process as raw materials, achieving efficient separation of fluorine and rare earth elements and full-process recycling. This design avoids the complexity of precipitation treatment in traditional processes, eliminates the hidden dangers of solid waste emissions, and improves the resource utilization rate of the rare earth smelting process.

[0025] (4) Strong process compatibility and easy operation. The process reaction conditions are mild, the stirring intensity and reaction time are easy to control, and it can seamlessly connect the upstream and downstream processes of rare earth smelting, with good process compatibility. No complex equipment or extreme operating environment is required, which lowers the threshold for process implementation and improves production efficiency.

[0026] (5) Ensure the stability of the extraction process and product quality. 2+ Fluoride ions in colloidal form prevent emulsification of the organic phase during the extraction process, while also addressing the negative impact of fluoride ions on the grade of rare earth products, ensuring the stable operation of subsequent extraction processes and the preparation of high-purity rare earth products, and fundamentally improving the cleanliness level and product quality standards of the entire rare earth smelting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the drawings required for describing the specific implementation or the prior art will be briefly introduced below. Obviously, the drawings described below are only one implementation of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 Schematic diagram of the process flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention provides a method for efficiently removing fluoride ions from a high-chloride rare earth solution with rare earth carbonate, thereby solving the problems of difficult precipitation treatment, large rare earth loss, and fluorine-containing waste gas pollution in the prior art high-chloride rare earth solution defluorination process. The overall approach to solving the above technical problems in the present invention is as follows:

[0030] The rare earth compounds used are primarily cerium carbonates. Because cerium accounts for approximately 80% of the cerium content in bastnaesite, the addition of this defluoridating agent has minimal impact on the rare earth distribution of the already highly chlorided rare earth feed solution and does not introduce other impurities to contaminate the rare earth feed solution. Furthermore, cerium has long been in a state of overcapacity, resulting in a low cost. Chemical precipitation allows for efficient defluoridation, ultimately achieving efficient separation of fluorine and rare earths. Furthermore, the rare earth precipitation residue can be directly returned to the alkaline decomposition process as raw material, thus achieving the recycling of rare earth resources.

[0031] In order to better understand the above technical solution, the above technical solution is described in detail below with specific implementation methods.

[0032] Example 1: This example uses a method for efficiently removing fluoride ions from a high-chloride rare earth feed solution using cerium carbonate to treat a high-chloride rare earth feed solution from a domestic rare earth smelting company. Testing revealed that the high-chloride rare earth feed solution contained, by weight, 280.82 g / L of REO, 0.378 g / L of F, 3 g / L of CaO, 1.52 g / L of MgO, 0.15 g / L of Al2O3, 2.25 g / L of BaO, and 0.2 g / L of ZnO. Hydrochloric acid was first added to adjust the pH of the high-chloride rare earth feed solution to less than 2. Then, a cerium carbonate defluoridant was added at 6% of the mass of the rare earth feed solution. The reaction temperature was controlled at 60°C for 2 hours with a stirring speed of 400 r / min. The mixture was then allowed to stand for 1 hour, followed by addition of NaOH to adjust the pH of the feed solution to 3.98. Finally, solid-liquid separation was performed. At this time, the fluorine removal rate of the rare earth liquid exceeds 92.5%, and the REO / F concentration ratio of the rare earth liquid after fluorine removal exceeds 55,000.

[0033] Example 2: This example uses a method for efficiently removing fluoride ions from a high-chloride rare earth feed solution using cerium carbonate to treat a high-chloride rare earth feed solution from a domestic rare earth smelting company, B. Testing revealed that the high-chloride rare earth feed solution contained, by weight, 249.2 g / L of REO, 0.578 g / L of F, 1.87 g / L of CaO, 1.02 g / L of MgO, 0.12 g / L of Al2O3, 2.78 g / L of BaO, and 0.19 g / L of ZnO. Hydrochloric acid was first added to adjust the pH of the high-chloride rare earth feed solution to <1. Then, cerium carbonate, a defluoridating agent, was added at 8% by weight of the rare earth feed solution. The reaction temperature was controlled at 80°C for 3 hours with a stirring speed of 600 r / min. The mixture was then allowed to stand for 1 hour, and NaOH was added to adjust the pH of the feed solution to 4.05. Finally, solid-liquid separation was performed. At this time, the fluorine removal rate of the rare earth liquid exceeds 97.8%, and the REO / F concentration ratio of the rare earth liquid after fluorine removal exceeds 58,000.

[0034] Example 3: This example describes a method for efficiently removing fluoride ions from a high-chloride rare earth feed solution using cerium carbonate. The high-chloride rare earth feed solution of a domestic C rare earth smelting enterprise was used to treat the high-chloride rare earth feed solution. Testing revealed that the high-chloride rare earth feed solution contained 98.7 g / L REO, 0.415 g / L F, 1.04 g / L CaO, 1.34 g / L MgO, 0.09 g / L Al2O3, 2.86 g / L BaO, and 0.35 g / L ZnO by weight. Hydrochloric acid was first added to adjust the pH of the high-chloride rare earth feed solution to <1. A cerium carbonate defluoridant was then added, accounting for 8% of the mass of the rare earth feed solution. The reaction temperature was controlled at 60°C for 2.5 hours with a stirring speed of 500 r / min. The mixture was then allowed to stand for 1 hour, and NaOH was added again to adjust the pH of the feed solution to 3.85. Finally, solid-liquid separation was performed. At this time, the fluorine removal rate of the rare earth liquid exceeds 95.7%, and the REO / F concentration ratio of the rare earth liquid after fluorine removal exceeds 56,000.

[0035] Example 4: This example uses a method for efficiently removing fluoride ions from a high-chloride rare earth feed solution using cerium carbonate to treat a high-chloride rare earth feed solution from a domestic rare earth smelting company D. Testing revealed that the high-chloride rare earth feed solution contained, by weight, 315.64 g / L of REO, 0.539 g / L of F, 2.67 g / L of CaO, 1.22 g / L of MgO, 0.12 g / L of Al2O3, 3.13 g / L of BaO, and 0.265 g / L of ZnO. Hydrochloric acid was first added to adjust the pH of the high-chloride rare earth feed solution to <1, and then cerium carbonate, a defluoridating agent, was added at 8% by mass of the rare earth feed solution. The reaction temperature was controlled at 90°C for 2 hours with a stirring speed of 500 r / min. The mixture was then allowed to stand for 1.2 hours, and then NaOH was added to adjust the pH of the feed solution to 4.13. Finally, solid-liquid separation was performed. At this time, the fluorine removal rate of the rare earth liquid exceeds 96.7%, and the REO / F concentration ratio of the rare earth liquid after fluorine removal exceeds 48,000.

[0036] Example 5: This example uses a method for efficiently removing fluoride ions from a high-chloride rare earth feed solution using cerium carbonate to treat a high-chloride rare earth feed solution from a domestic E rare earth smelting enterprise. Testing revealed that the high-chloride rare earth feed solution contained, by weight, 236.9 g / L of REO, 0.333 g / L of F, 1.01 g / L of CaO, 1.21 g / L of MgO, 0.17 g / L of Al2O3, 3.16 g / L of BaO, and 0.347 g / L of ZnO. Hydrochloric acid was first added to adjust the pH of the high-chloride rare earth feed solution to <1, and then cerium carbonate, a defluoridating agent, was added at 8% by weight of the rare earth feed solution. The reaction temperature was controlled at 90°C for 3.2 hours with a stirring speed of 600 r / min. The mixture was then allowed to stand for 0.5 hours, and then NaOH was added to adjust the pH of the feed solution to 4.16. At this time, the fluorine removal rate of the rare earth liquid exceeds 96.8%, and the REO / F concentration ratio of the rare earth liquid after fluorine removal exceeds 50,000.

[0037] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0038] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth cerium carbonate, characterized in that: The steps include: S1. Prepare a high-chloride rare earth solution, the composition of which includes REO 200g / L~400g / L, F 0.1g / L~0.8g / L, CaO 1g / L~5g / L, MgO 1g / L~5g / L, Al2O3 0.1g / L~0.3g / L, BaO 2.0g / L~3.5g / L, and ZnO <0.4g / L; S2. Add hydrochloric acid to adjust the pH value of the high-chloride rare earth solution to pH < 2; S3, raising the temperature of the acidic high-chloride rare earth liquid to 60°C to 100°C, adding a rare earth cerium carbonate defluoridation agent, stirring to react, and then standing to keep warm; S4. NaOH is added to adjust the pH value of the rare earth liquid to below 4.5, and then solid-liquid separation is performed to obtain a defluorinated rare earth liquid and a precipitated residue.

2. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth carbonate according to claim 1, wherein: The added amount of the rare earth cerium carbonate defluoridating agent is 1% to 15% of the mass of the rare earth liquid.

3. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth carbonate according to claim 1, wherein: After adding the rare earth cerium carbonate defluoridant, mix and stir to react for 2h to 4h, and then let it stand and keep warm for 0.5h to 1.5h.

4. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth carbonate according to claim 1, wherein: The particle size of the rare earth cerium carbonate defluoridating agent is controlled to be 50 μm to 200 μm.

5. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth cerium carbonate according to claim 1, wherein: The purity of the rare earth cerium carbonate defluoridating agent is higher than 90%.

6. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth carbonate according to claim 1, characterized in that: The stirring intensity is controlled at 200r / min~700r / min.

7. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth carbonate according to claim 1, characterized in that: The fluorine removal rate of the high-chloride rare earth feed solution exceeds 90%, and the feed solution REO / F concentration ratio exceeds 40,000.

8. The method for efficiently removing fluoride ions from a high-chloride rare earth solution using rare earth carbonate according to claim 1, wherein: The defluorinated rare earth liquid enters the extraction process for rare earth extraction and refining. The precipitated residue is a fluorocarbon rare earth compound, which is returned to the alkaline decomposition process of rare earth hydrometallurgy for rare earth recovery again.

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