Method for removing aluminum and fluorine impurities from ion-adsorbed rare earth chloride leach solution

Abstract

The application discloses a method for removing aluminum and fluorine impurities from ion-adsorbed rare earth chloride leaching solution, and comprises the following steps: using an acidic solution to leach ion-type rare earth ore to obtain rare earth ore leaching solution; adding a first removing agent into the rare earth ore leaching solution and stirring uniformly to obtain a first mixed solution; adding a second removing agent into the first mixed solution and adjusting the pH by the second removing agent to obtain a second mixed solution; adding an adsorbent into the second mixed solution, and after reaction and standing, performing solid-liquid separation to obtain filtrate A and residue A. The first removing agent is used to remove SO4 2‑ from the system, the second removing agent is used to adjust the pH of the system to make aluminum ions form a precipitate, and finally, the adsorbent is used to deeply remove residual aluminum and fluorine, thereby effectively reducing the aluminum and fluorine impurity content in the rare earth chloride leaching solution under the premise that rare earth elements are not lost in a large amount by co-precipitation, and solving the problems of low impurity removal efficiency, high impurity removal cost and large rare earth loss in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of rare earth production technology, and in particular relates to a method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption. Background Technology

[0002] In the industrial production of rare earths, the ammonium salt in-situ leaching process is commonly used to recover rare earths. This involves using ammonium sulfate to leach rare earth elements from the ore, followed by ammonium bicarbonate to remove impurities and precipitate and enrich the rare earths in the leachate. In recent years, the large-scale use of ammonium sulfate has led to a significant influx of ammonium and sulfate ions into the mountains, resulting in excessive ammonia nitrogen levels in the surrounding environment and causing damage to the local ecosystem. Therefore, the ammonium sulfate leaching process has been discontinued, and a shift towards ammonia-free leaching technologies is underway. However, in existing leaching processes using ore-leaching agents, impurity ions adhering to the surface of rare earth minerals are easily leached out in subsequent processes. During the subsequent rare earth extraction and separation, the concentration of impurity ions gradually increases. In particular, large amounts of fluoride and aluminum ions in the rare earth solution form insoluble precipitates that enter the extraction organic phase, affecting the efficiency of subsequent rare earth extraction and separation. Therefore, efficiently removing fluoride and aluminum impurities from the rare earth feed solution is crucial for improving the quality and extraction rate of rare earth metals. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for removing aluminum and fluorine impurities from rare earth chloride leaching solutions using ion adsorption.

[0004] The present invention is achieved through the following technical solutions.

[0005] This invention provides a method for removing aluminum and fluorine impurities from rare earth chloride leaching solutions via ion adsorption, comprising the following steps: S1: Leach ion-adsorption rare earth ore using an acidic solution to obtain rare earth ore leachate; S2: Take the rare earth ore leachate, preheat it, and keep it at a constant temperature for 5-10 minutes. S3: Add the first removal agent to the rare earth ore leaching solution and stir evenly to obtain the first mixture; S4: Add the second removal agent to the first mixture, stir at a constant speed, and adjust the pH to 4.5-5.4 by relying on the second removal agent to obtain the second mixture; S5: Add adsorbent to the second mixture and stir at a constant speed for 1-3 hours; S6: Keep the mixture at the reaction temperature for 4-8 hours to separate the solid and liquid, and obtain filtrate A and filter residue A. Collect filtrate A.

[0006] Preferably, in step S2, the purpose of adding the first removal agent to the rare earth ore leachate is to remove SO4 from the rare earth ore leachate. 2- , excluding SO4 2-Interference with the impurity removal system.

[0007] Preferably, the acidic solution is hydrochloric acid.

[0008] Preferably, the average REO concentration of the rare earth ore leachate is 1.4-1.5 mol / L, and the pH is 0.5-0.6.

[0009] Preferably, the first removal agent is barium chloride.

[0010] Preferably, the second removal agent is magnesium oxide.

[0011] Preferably, the adsorbent is magnesium carbonate.

[0012] Preferably, the amount of the first removal agent added is 3%-5% of the total amount of rare earth oxides contained in the leachate.

[0013] Preferably, the amount of adsorbent added is 4%-8% of the total amount of rare earth oxides contained in the leachate.

[0014] Preferably, in S1-S6, the reaction temperature is 30-90℃ and the stirring speed is 200-400rpm.

[0015] The beneficial effects of this invention are as follows: This invention employs a stepwise impurity removal process, first removing SO4 through barium chloride precipitation. 2- , excluding SO4 2- To mitigate interference with the impurity removal system, magnesium oxide is used to adjust the pH and initially precipitate aluminum impurities. Simultaneously, magnesium oxide provides Mg... 2+ With F - The MgF2 is formed by combining with magnesium carbonate, which further stabilizes the pH and replenishes the Mg. 2+ Simultaneously, it deeply adsorbs and removes residual aluminum and fluorine, achieving efficient removal of aluminum and fluorine impurities while ensuring rare earth yield. This solves the problems of low impurity removal rate and large rare earth loss in existing ion adsorption-type rare earth chloride leaching solutions. The reagents used in this invention are all conventional chemical raw materials, with low cost and simple operation. It does not require large-scale modification of existing production equipment, making it suitable for industrial-scale impurity removal of ion adsorption-type rare earth ores. The impurity content of the obtained rare earth chloride solution after impurity removal meets the feed requirements for subsequent rare earth extraction and separation, demonstrating good industrial application prospects. 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: A method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption includes the following steps: S1: Hydrochloric acid was used to perform optimal leaching of ion-adsorption rare earth minerals to obtain rare earth mineral leachate. The average REO concentration of the rare earth mineral leachate was 1.435 mol / L and the pH was 0.67. S2: Take 250ml of the extract, preheat the temperature to 40℃, and keep it warm for 5 minutes. S3: Stir the rare earth ore leaching solution at a speed of 300 rpm, and add barium chloride to the rare earth ore leaching solution while stirring to obtain the first mixture; the added barium chloride reacts fully with the residual sulfate ions in the leaching solution to generate barium sulfate precipitate for pre-removal, so as to avoid introducing unnecessary impurities in subsequent processes; S4: Add 4.1 times the amount of magnesium oxide theoretically required to completely neutralize the free acid in the leachate to the first mixture, adjust the pH, and obtain the second mixture; by adjusting the pH with magnesium oxide, no additional impurities such as ammonium ions and sodium ions will be introduced throughout the process, and no ammonia nitrogen pollution will be generated. At the same time, a suitable acid-base environment will be created for the subsequent precipitation of aluminum ions. S5: Add magnesium carbonate (4% of the total rare earth oxides contained in 250ml of the leachate) to the second mixture and react for 3 hours. S6: After standing for 8 hours, the solid-liquid separation operation is completed by a filter press, and finally filtrate A with low impurity content and filter residue A enriched with aluminum and fluorine impurities are obtained. Filtrate A is collected.

[0018] Filtrate A is an ion-adsorption type rare earth chloride feed solution. After solid-liquid separation, the aluminum removal rate of filtrate A is greater than 97.17%, the fluorine removal rate is 94.29%, and the rare earth single-pass recovery rate is 78.75%.

[0019] Example 2: A method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption includes the following steps: S1: Hydrochloric acid was used to perform optimal leaching of ion-adsorption rare earth minerals to obtain rare earth mineral leachate. The average REO concentration of the rare earth mineral leachate was 1.435 mol / L and the pH was 0.67. S2: Take 250ml of the extract, preheat the temperature to 90℃, and keep it warm for 5 minutes. S3: Stir the rare earth ore leaching solution at a speed of 400 rpm, and add barium chloride to the rare earth ore leaching solution while stirring to obtain the first mixture; S4: Add 4.1 times the amount of magnesium oxide theoretically required to completely neutralize the free acid in the leachate to the first mixture, adjust the pH to 5.4, and obtain the second mixture; S5: Add magnesium carbonate (8% of the total rare earth oxides contained in the leachate) to 250 ml of the second mixture, and react at 90 °C for 1 h. S6: After standing for 4 hours, the solid-liquid separation operation is completed by a filter press, and finally filtrate A with low impurity content and filter residue A enriched with aluminum and fluorine impurities are obtained. Filtrate A is collected.

[0020] After solid-liquid separation, the aluminum removal rate of filtrate A was 96.61%, the fluorine removal rate was 90.99%, and the rare earth recovery rate was 80.14%.

[0021] Example 3: A method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption includes the following steps: S1: Hydrochloric acid was used to perform optimal leaching of ion-adsorption rare earth minerals to obtain rare earth mineral leachate. The average REO concentration of the rare earth mineral leachate was 1.435 mol / L and the pH was 0.67. S2: Take 250ml of the extract, preheat the temperature to 60℃, and keep it warm for 10 minutes. S3: Stir the rare earth ore leaching solution at a speed of 300 rpm, and add barium chloride to the rare earth ore leaching solution while stirring to obtain the first mixture; S4: Add 3.8 times the amount of magnesium oxide theoretically required to completely neutralize the free acid in the leachate to the first mixture, adjust the pH to 5.2, and obtain the second mixture; S5: Add magnesium carbonate (6% of the total rare earth oxides contained in the leachate) to 250 ml of the second mixture, and react at 60 °C for 2 h. S6: After standing for 5 hours, the solid-liquid separation operation is completed by a filter press, and finally filtrate A with low impurity content and filter residue A enriched with aluminum and fluorine impurities are obtained. Filtrate A is collected.

[0022] After solid-liquid separation, the aluminum removal rate of filtrate A was greater than 97.17%, the fluorine removal rate was 89.30%, and the rare earth recovery rate was 80.14%.

[0023] Example 4: A method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption includes the following steps: S1: Hydrochloric acid was used to perform optimal leaching of ion-adsorption rare earth minerals to obtain rare earth mineral leachate. The average REO concentration of the rare earth mineral leachate was 1.47 mol / L and the pH was 0.58. S2: Take 250ml of the extract, preheat the temperature to 70℃, and keep it warm for 10 minutes. S3: Stir the rare earth ore leaching solution at a speed of 300 rpm, and add barium chloride to the rare earth ore leaching solution while stirring to obtain the first mixture; S4: Add magnesium oxide, which is theoretically required to completely neutralize the free acid in the leachate, to the first mixture, and adjust the pH to 5.3 to obtain the second mixture; S5: Add magnesium carbonate (6% of the total rare earth oxides contained in the leachate) to 250 ml of the second mixture, and react at 70 °C for 1 h. S6: After standing for 5 hours, the solid-liquid separation operation is completed by a filter press, and finally filtrate A with low impurity content and filter residue A enriched with aluminum and fluorine impurities are obtained. Filtrate A is collected.

[0024] After solid-liquid separation, the aluminum removal rate of filtrate A was 97.85%, the fluorine removal rate was 97.77%, and the rare earth recovery rate was 82.65%.

[0025] Example 5: A method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption includes the following steps: S1: Hydrochloric acid was used to perform optimal leaching of ion-adsorption rare earth minerals to obtain rare earth mineral leachate. The average REO concentration of the rare earth mineral leachate was 1.47 mol / L and the pH was 0.58. S2: Take 250ml of the extract, preheat the temperature to 80℃, and keep it warm for 10 minutes. S3: Stir the rare earth ore leaching solution at a speed of 200-400 rpm, and add barium chloride to the rare earth ore leaching solution while stirring to obtain the first mixture; S4: Add magnesium oxide, which is theoretically required to completely neutralize the free acid in the leachate, to the first mixture, and adjust the pH to 5.2 to obtain the second mixture; S5: Add magnesium carbonate (6% of the total rare earth oxides contained in the leachate) to 250 ml of the second mixture, and react at 80 °C for 2 h. S6: After standing for 8 hours, the solid-liquid separation operation is completed by a filter press, and finally filtrate A with low impurity content and filter residue A enriched with aluminum and fluorine impurities are obtained. Filtrate A is collected.

[0026] After solid-liquid separation, the aluminum removal rate of filtrate A was 97.42%, the fluorine removal rate was 91.53%, and the rare earth recovery rate was 82.87%.

[0027] Example 6: A method for removing aluminum and fluorine impurities from rare earth chloride leaching solution by ion adsorption includes the following steps: S1: Hydrochloric acid was used to perform optimal leaching of ion-adsorption rare earth minerals to obtain rare earth mineral leachate. The average REO concentration of the rare earth mineral leachate was 1.47 mol / L and the pH was 0.58. S2: Take 250ml of the extract, preheat the temperature to 60℃, and keep it warm for 8 minutes. S3: Stir the rare earth ore leaching solution at a speed of 300 rpm, and add barium chloride to the rare earth ore leaching solution while stirring to obtain the first mixture; S4: Add magnesium oxide, which is theoretically required to completely neutralize the free acid in the leachate, to the first mixture, and adjust the pH to 5.1 to obtain the second mixture; S5: Add magnesium carbonate (6% of the total rare earth oxides contained in the leachate) to 250 ml of the second mixture, and react at 60 °C for 1 h. S6: After standing for 8 hours, the solid-liquid separation operation is completed by a filter press, and finally filtrate A with low impurity content and filter residue A enriched with aluminum and fluorine impurities are obtained. Filtrate A is collected.

[0028] After solid-liquid separation, the aluminum removal rate of filtrate A was greater than 97.85%, the fluorine removal rate was 92.24%, and the rare earth recovery rate was 80.61%.

[0029] The ion-adsorption type rare earth chloride solution prepared in Examples 1-6 was subjected to impurity removal treatment. The contents of aluminum, fluorine and rare earth in the ion-adsorption type rare earth chloride solution before and after impurity removal treatment were detected. The specific results are shown in the table below.

[0030] As shown in the table above, this invention, through the stepwise addition of a first removal agent, a second removal agent, and an adsorbent, sequentially precipitates and adsorbs aluminum and fluorine impurities in the leachate. The aluminum removal rate can reach over 97%, and the fluorine removal rate can reach over 89%, while maintaining a rare earth yield of over 78%. Simultaneously, the Al2O3 / REO impurity content can be controlled below 600 ppm, with a minimum reduction to below 500 ppm, and the fluorine impurity content can be reduced to below 700 ppm, fully meeting the feed requirements for subsequent rare earth extraction and separation processes. It avoids the emulsification problem of insoluble fluorine-aluminum compounds containing organic phases. The method of this application has excellent impurity removal effect and can meet the subsequent purification and processing requirements of ion-adsorption type rare earth chloride leachates.

[0031] In this application, the filter residue A obtained from the S3 separation can be recycled by acid dissolution to recover the valuable rare earth elements entrained therein. The recovered rare earth solution is returned to the front-end leaching process for recycling, and the total rare earth recovery rate can be increased to over 99%, with no secondary solid waste waste.

Claims

1. A method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution, characterized in that, Includes the following steps: S1: Leach ion-adsorption rare earth ore using an acidic solution to obtain rare earth ore leachate; S2: Take the rare earth ore leaching solution, heat it up, and keep it at a constant temperature for 5-10 minutes; S3: Add the first removal agent to the rare earth ore leaching solution and stir evenly to obtain the first mixture; S4: Add the second removal agent to the first mixture, stir at a constant speed, and adjust the pH to 4.5-5.4 by relying on the second removal agent to obtain the second mixture; S5: Add adsorbent to the second mixture and stir at a constant speed for 1-3 hours; S6: Keep the mixture at a constant temperature for 4-8 hours at the reaction temperature to separate the solid and liquid, and obtain filtrate A and filter residue A. Collect filtrate A.

2. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: In step S3, a first removal agent is added to the rare earth ore leaching solution.

3. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The acidic solution is hydrochloric acid.

4. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The average REO concentration of the rare earth ore leaching solution is 1.4-1.5 mol / L, and the pH is 0.5-0.

6.

5. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The first removal agent is barium chloride.

6. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The second removal agent is magnesium oxide.

7. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The adsorbent is magnesium carbonate.

8. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The amount of the first removal agent added is 3%-5% of the total amount of rare earth oxides contained in the leachate.

9. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: The amount of adsorbent added is 4%-8% of the total amount of rare earth oxides contained in the leachate.

10. The method for removing aluminum and fluorine impurities from an ion-adsorption type rare earth chloride leaching solution as described in claim 1, characterized in that: In S1-S6, the reaction temperature is 30-90℃ and the stirring speed is 200-400rpm.

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