Defluorination method for rare earth ore leaching material liquid

Abstract

The invention discloses a defluorination method of rare earth ore leaching feed liquid, which comprises the following steps: adding a defluorination agent into the rare earth feed liquid, and continuously stirring until the pH value is stable; adding a precipitant I, and continuously stirring until the mixture is uniformly mixed; adding a second precipitant, and continuously stirring for more than 1 hour; and standing for clarification, and then carrying out solid-liquid separation to obtain low-fluorine rare earth feed liquid. According to the method, the fluorine removal agent and the precipitator are combined to remove fluorine in the rare earth feed liquid, the pH value of the solution is controlled, the settling speed of generated calcium fluoride is increased, fluorine in the high-fluorine feed liquid leached from the rare earth ore can be efficiently removed, and the rare earth entrainment loss is reduced.

Description

Technical Field

[0001] This invention belongs to the field of rare earth production technology, and in particular relates to a method for defluorinating rare earth ore leaching solutions. Background Technology

[0002] Currently, the main methods for processing rare earth ores are concentrated sulfuric acid roasting and sodium hydroxide decomposition.

[0003] Mixed rare earth chloride solutions can be obtained through processes such as high-temperature concentrated sulfuric acid decomposition, water leaching, impurity removal, conversion, and separation. However, fluorite, apatite, and bastnaesite are commonly found as associated minerals in mines, increasing the concentration of F in the leachate. - The concentration is as high as 0.3-1.5 g / L. If fluoride is not specifically removed, it will persist throughout the entire process from extraction, precipitation, crystallization, electrolysis to the preparation of metals and magnetic materials, causing five major problems: equipment corrosion, poisoning of the organic phase, reduced extraction rate, product contamination, and increased environmental taxes. Therefore, fluoride removal from rare earth feed solutions has become a mandatory requirement for industry entry. Fluoride removal from rare earth feed solutions is no longer a simple environmental task, but a systemic project encompassing resource utilization, product quality, equipment lifespan, and occupational health. With the increasing demand for fluoride in high-performance magnetic materials, hydrogen storage, and polishing powders, the use of fluoride in rare earths is also growing. - The requirement to reduce the content from "ppm level" to "ppb level" necessitates a highly efficient defluorination method with low rare earth entrainment loss. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for defluorination of rare earth ore leaching solution.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a method for defluorinating rare earth ore leaching solution, comprising the following steps: S1: Add defluorinating agent to rare earth solution and stir continuously until pH value stabilizes; S2: Add precipitant No. 1 and continue stirring until the mixture is homogeneous; S3: Add No. 2 precipitant and stir continuously for more than 1 hour; S4: Let stand and clarify, then perform solid-liquid separation to obtain low-fluorine rare earth solution.

[0007] Preferably, in step S1, stirring is continued until the pH value stabilizes at 4.7-5.3.

[0008] Preferably, the amount of the defluorinating agent is 0.01-0.03 g / mL based on the volume of the rare earth liquid, the amount of the first precipitant added is 6-10% of the mass of the rare earth liquid, and the amount of the second precipitant added is 3-7% of the mass of the rare earth liquid.

[0009] Preferably, the first precipitant comprises a mixture of carbonate and ionic rare earth slag.

[0010] Preferably, the mass ratio of the carbonate and rare earth slag mixture is 1:(0.05-0.16), and the carbonate is solid calcium carbonate.

[0011] Preferably, the second precipitant comprises a carbonate.

[0012] Preferably, the concentration of the carbonate is 2-2.6 mg / L, and the carbonate is sodium carbonate.

[0013] Preferably, the defluorinating agent is calcium oxide.

[0014] The beneficial effects of this invention are as follows: This invention combines a defluorinating agent and a precipitant for the defluorination of rare earth leaching solutions. By controlling the pH value of the solution and increasing the sedimentation rate of calcium fluoride, fluoride in high-fluoride solutions from rare earth ore leaching can be efficiently removed, and rare earth entrainment losses can be reduced. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0017] Example 1: like Figure 1 As shown, a method for defluorinating rare earth ore leaching solution includes the following steps: S1: Add 4g of defluorinating agent to 400mL of rare earth sulfuric acid leaching solution with an initial fluoride ion concentration of 3.1g / L, and stir continuously until the pH value stabilizes at 4.7. S2: Add 24g of No. 1 precipitant and stir continuously until the mixture is uniform; S3: Add 12g of No. 2 precipitant and stir continuously for 1.5 hours; S4: Let stand for 2 hours to clarify, then perform solid-liquid separation. The supernatant is a low-fluorine rare earth solution.

[0018] The No. 1 precipitant comprises a mixture of solid calcium carbonate and ionic rare earth slag.

[0019] The mass ratio of the solid calcium carbonate and rare earth slag mixture is 1:0.05.

[0020] The second precipitant is sodium carbonate with a concentration of 2 mg / L.

[0021] Example 2: like Figure 1As shown, a method for defluorinating rare earth ore leaching solution includes the following steps: S1: Add 12g of defluorinating agent to 400mL of rare earth sulfuric acid leaching solution with an initial fluoride ion concentration of 3.1g / L, and stir continuously until the pH value stabilizes at 5.2; S2: Add 40g of No. 1 precipitant and stir continuously until the mixture is uniform; S3: Add 28g of No. 2 precipitant and stir continuously for 1.5 hours; S4: Let stand for 2 hours to clarify, then perform solid-liquid separation. The supernatant is a low-fluorine rare earth solution.

[0022] The No. 1 precipitant comprises a mixture of solid calcium carbonate and ionic rare earth slag.

[0023] The mass ratio of the solid calcium carbonate and rare earth slag mixture is 1:0.16.

[0024] The second precipitant is sodium carbonate with a concentration of 2.6 mg / L.

[0025] Example 3: like Figure 1 As shown, a method for defluorinating rare earth ore leaching solution includes the following steps: S1: Add g of defluorinating agent to 400 mL of rare earth sulfuric acid leaching solution with an initial fluoride ion concentration of 3.1 g / L, and continue stirring until the pH value stabilizes at 5; S2: Add 32g of No. 1 precipitant and stir continuously until the mixture is uniform; S3: Add 16g of No. 2 precipitant and stir continuously for 1.5 hours; S4: Let stand for 2 hours to clarify, then perform solid-liquid separation. The supernatant is a low-fluorine rare earth solution.

[0026] The No. 1 precipitant comprises a mixture of solid calcium carbonate and ionic rare earth slag.

[0027] The mass ratio of the solid calcium carbonate and rare earth slag mixture is 1:0.11.

[0028] The second precipitant is sodium carbonate with a concentration of 2.3 mg / L.

[0029] In Examples 1-3, the defluorinating agent was calcium oxide, and the ionic rare earth slag mixture was carbonate slag after acid dissolution and impurity removal process.

[0030] Comparative Example 1: The existing calcium salt precipitation method, which involves adding only calcium oxide, was used to defluorinate 400 mL of rare earth sulfuric acid leaching solution with an initial fluoride concentration of 3.1 g / L. The supernatant was collected after solid-liquid separation.

[0031] The results of treating rare earth sulfuric acid leaching solutions using the methods of Examples 1-3 and Comparative Example 1 are shown in the table below.

[0032] As shown in the table above, the defluorination rate of the method of the present invention is as high as 77.42% or more. In the method of the present invention, the defluorinating agent used releases a large amount of OH under acidic conditions. - At the same time, reduce Fe 3+ Al 3+ Impurity ions against F - The complexation and masking of the precipitant enhances the effective freeness of fluorine. The first precipitant uses existing CaF2 microcrystals as "seeds," inducing the epitaxial growth of new CaF2 on its surface, lowering the nucleation energy barrier, and increasing the settling velocity. Meanwhile, the colloidal substances in the slag can also co-flocculate the CaF2 particles. The colloidal substances in the slag achieve co-flocculation through "charge neutralization + adsorption bridging": after the surface charge of the colloidal substances is neutralized, they adsorb onto the surface of the CaF2 particles, firmly encapsulating the dispersed CaF2 particles and the trace rare earth ions adsorbed on them, forming a dense composite flocculent. This prevents rare earth ions from being lost with the supernatant due to adsorption on the surface of fine particles, reducing rare earth entrainment loss. The second precipitant partially hydrolyzes to provide CO3. 2- / HCO 3- It reacts with rare earth ions to form RE(CO3). + RE(OH) 2+ Isocomplex cations; these cations are related to F - Ca 2+ Copolymerization generates CaF2-RE2(CO3)3 composite flocs, which encapsulate fluorine into rare earth waste residue, achieving the goal of defluorination of rare earth liquid.

[0033] The existing technology method in Comparative Example 1 has a fluoride removal rate of only 48.39%, and the rare earth loss rate is significantly higher than that of the method of the present invention.

Claims

1. A method for defluorinating rare earth ore leaching solution, characterized in that, Includes the following steps: S1: Add defluorinating agent to rare earth solution and stir continuously until pH value stabilizes; S2: Add precipitant No. 1 and continue stirring until the mixture is homogeneous; S3: Add No. 2 precipitant and stir continuously for more than 1 hour; S4: Let stand and clarify, then perform solid-liquid separation to obtain low-fluorine rare earth solution.

2. The method for defluorinating rare earth ore leaching solution as described in claim 1, characterized in that: In step S1, stirring is continued until the pH value stabilizes at 4.7-5.

3.

3. The method for defluorinating rare earth ore leaching solution as described in claim 1, characterized in that: The amount of the defluorinating agent is 0.01-0.03 g / mL based on the volume of the rare earth liquid. The amount of the first precipitant added is 6-10% of the mass of the rare earth liquid, and the amount of the second precipitant added is 3-7% of the mass of the rare earth liquid.

4. The method for defluorinating rare earth ore leaching solution as described in claim 1, characterized in that: The No. 1 precipitant comprises a mixture of carbonates and ionic rare earth slag.

5. The method for defluorinating rare earth ore leaching solution as described in claim 4, characterized in that: The mass ratio of the carbonate and rare earth slag mixture is 1:(0.05-0.16), and the carbonate is solid calcium carbonate.

6. The method for defluorinating rare earth ore leaching solution as described in claim 1, characterized in that: The second precipitant includes carbonates.

7. The method for defluorinating rare earth ore leaching solution as described in claim 6, characterized in that: The concentration of the carbonate is 2-2.6 mg / L, and the carbonate is sodium carbonate.

8. The method for defluorinating rare earth ore leaching solution as described in claim 1, characterized in that: The defluorinating agent is calcium oxide.

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