A method for inhibiting leaching of impurity aluminum ions in an ionic rare earth ore

Abstract

The application discloses a method for inhibiting leaching of impurity aluminum ions in ionic rare earth ore, and belongs to the technical field of rare earth ore mining. S1, according to the rare earth content in the ore body, a leaching agent is configured; S2, a buffer is added to the step S1 to configure a composite leaching agent; S3, the composite leaching agent in the step S2 is added to the ore body for leaching; S4, the buffer in the step S2 is configured into a buffer solution with the same pH buffering capacity as the composite leaching agent; S5, after the composite leaching agent in the step S2 is added completely, the buffer solution in the step S4 is continuously added to the ore body until the leaching is completed; the composite leaching agent containing a specific buffer is configured, the pH value of the leaching solution in the leaching process is stably controlled within the range from 4.8 to 5.4; under the pH condition, aluminum ions can form aluminum hydroxide precipitate colloid and are adsorbed in the ore body, while rare earth ions can still stably exist in the leaching solution, so that in-situ separation of the rare earth and the aluminum ions in the leaching stage is realized.

Description

Technical Field

[0001] This invention belongs to the field of rare earth mining technology, specifically, it relates to a method for suppressing the leaching of aluminum ions, an impurity, in ion-type rare earth ores. Background Technology

[0002] In ion-adsorption rare earth ores, rare earth elements are mainly adsorbed onto the surface of clay minerals in ionic form. Currently, industrially, inorganic salt electrolytes (such as ammonium sulfate and magnesium sulfate) are commonly used to leach rare earth ions from the ore body through ion exchange. However, in traditional leaching processes, the pH value of the leaching agent fluctuates significantly as rare earth ions are continuously leached. Furthermore, the ore body itself has a certain acid-base buffering capacity, resulting in the pH value of the leachate typically fluctuating within the range of 3.8-4.2. Under these pH conditions, a large number of aluminum ions, impurities in the ore body, are exchanged into the leachate along with the rare earth ions. Because the ionic radii of aluminum ions and rare earth ions are similar, they are difficult to separate efficiently in subsequent extraction processes, severely affecting the purity and quality of rare earth products.

[0003] To address the aforementioned issues, existing technologies typically employ ammonium bicarbonate-precipitation to separate aluminum and rare earth ions during the rare earth leaching enrichment stage. This method adjusts the pH of the leaching solution using ammonium bicarbonate, causing aluminum ions to precipitate as aluminum hydroxide and be removed. However, the pH value required for complete precipitation of aluminum ions (approximately 5.5) is extremely close to the pH value at which rare earth ions begin to precipitate (approximately 5.4), resulting in a rare earth loss rate as high as 5-10% during this purification process, significantly reducing the recovery rate of rare earth resources. Furthermore, radioactive elements such as thorium in the leaching solution accumulate along with the aluminum precipitation during this purification process, causing the radioactivity levels of the purified residue to exceed standards. This necessitates special treatment as hazardous waste, increasing not only the environmental risks for enterprises but also their production costs. Summary of the Invention

[0004] In view of the problems mentioned in the prior art, the present invention provides a method for suppressing the leaching of aluminum ions, an impurity, in ion-type rare earth ores.

[0005] To solve the above problems, the present invention adopts the following technical solution.

[0006] A method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores comprises the following steps:

[0007] Step S1: Prepare the leaching agent according to the rare earth content in the ore body;

[0008] Step S2: Add a buffer to step S1 to prepare a composite leaching agent;

[0009] Step S3: Add the composite leaching agent from step S2 into the ore body for leaching;

[0010] Step S4: Prepare a buffer solution with the same pH buffering capacity as the composite leaching agent using the buffer from step S2.

[0011] Step S5: After the composite leaching agent in step S2 has been added, continue to add the buffer solution in step S4 to the ore body until the leaching is completed.

[0012] Preferably, the leaching agent includes one or more of sodium sulfate, magnesium sulfate, and ammonium sulfate.

[0013] Furthermore, the concentration of the leaching agent is 0.15 mol / L.

[0014] Preferably, the buffer comprises one of the following: acetate-sodium acetate, acetate-ammonium acetate, sodium dihydrogen phosphate-sodium hydrogen phosphate, and citric acid-sodium citrate.

[0015] Furthermore, the pH value of the buffer system is 4.8-5.4, and the concentration of the buffer system is 0.1-0.4 mol / L.

[0016] Furthermore, in step S2, when the buffer is acetic acid-ammonium acetate, the composite leaching agent is prepared by adding ammonium acetate and glacial acetic acid to the leaching agent solution.

[0017] Furthermore, in step S2, when the buffer is citric acid-sodium citrate, the composite leaching agent is prepared by adding citric acid and sodium citrate to the leaching agent solution.

[0018] Preferably, in step S4, the buffer solution is prepared by adding a corresponding buffer to a pure aqueous solution.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) This invention uses a composite leaching agent containing a specific buffer to stably control the pH value of the leachate during the leaching process within the range of 4.8-5.4. Under this pH condition, aluminum ions can form aluminum hydroxide precipitate colloids and be adsorbed into the ore body, while rare earth ions can still exist stably in the leachate, thus achieving in-situ separation of rare earth and aluminum ions during the leaching stage. According to data from specific embodiments, after adopting the method of this invention, the concentration of aluminum ions in the leaching mother liquor decreased from 101 mg / L in the traditional method to 7-26 mg / L, and the amount of aluminum ions leached decreased by 74.2%-93%, significantly reducing the load on subsequent impurity removal processes.

[0021] (2) By separating rare earth ions in situ during the leaching stage, the present invention avoids the loss of rare earth ions due to co-precipitation during the impurity removal process. The rare earth leaching rate in the present invention can reach 91.5%-92.3%, which is basically the same as the 92.5% of the traditional method, effectively ensuring the high recovery rate of rare earth resources.

[0022] (3) The present invention advances the separation of rare earth and aluminum ions to the leaching stage, eliminating the need for an additional ammonium bicarbonate impurity removal process after the leaching solution is enriched, which significantly shortens the process flow of rare earth production; at the same time, it reduces the consumption of chemical reagents such as ammonium bicarbonate and the treatment cost of impurity removal residue, thereby reducing the production economic cost of enterprises.

[0023] (4) The residue produced by traditional methods is enriched with radioactive thorium and other elements and needs to be managed as hazardous waste. However, this invention reduces the content of aluminum and radioactive elements in the leachate by inhibiting aluminum ion leaching, thereby reducing the radioactive risk of the residue and the amount of hazardous waste generated, which is beneficial to environmental protection and corporate environmental protection. Attached Figure Description

[0024] Figure 1 This is a comparison chart of the experimental results of the present invention;

[0025] Figure 2 This is a flowchart of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments. Generally, the components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Example

[0028] like Figure 2 As shown, a method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores comprises the following steps:

[0029] Step S1: Prepare the leaching agent:

[0030] Magnesium sulfate was used as the leaching agent. 36g of magnesium sulfate (MgSO4・7H2O, purity ≥99%) was weighed, dissolved in deionized water and diluted to 1000mL to obtain a magnesium sulfate solution with a concentration of 0.15mol / L as the leaching agent.

[0031] Step S2: Prepare the composite leaching agent:

[0032] Add the buffer acetic acid-sodium acetate to the magnesium sulfate solution in step S1: Weigh 13.6g of sodium acetate trihydrate (CH3COONa・3H2O, purity ≥99%) and 4.5mL of glacial acetic acid (CH3COOH, purity ≥99.5%, density 1.05g / cm³), add them to the magnesium sulfate solution above, and stir until completely dissolved to obtain a composite leaching agent with a total buffer concentration of 0.1mol / L and a pH value of 4.8 (monitored in real time with a pH meter and fine-tuned to 4.8).

[0033] Step S3: Leaching with composite leaching agent:

[0034] Five kilograms of ion-adsorption rare earth ore (rare earth grade 0.04%) was selected and uniformly packed into an acrylic leaching column with a diameter of 10 cm and a height of 45 cm (ore body compaction degree of 1.4 g / cm³). The composite leaching agent from step S2 was added to the leaching column at a uniform rate using a peristaltic pump (model BT100-2J, flow rate 1.5 mL / min) to conduct a column leaching test.

[0035] Step S4: Prepare the buffer solution:

[0036] Prepare a buffer solution with the same pH buffering capacity as the composite leaching agent using the buffering agent (acetic acid-sodium acetate) in step S2: Weigh 40.8g of sodium acetate trihydrate and 13.5mL of glacial acetic acid, add deionized water to dissolve and make up to 3000mL to obtain a buffer solution with a total buffer concentration of 0.1mol / L and a pH value of 4.8.

[0037] Step S5: The ore is leached further with the buffer solution.

[0038] After all the composite leaching agent from step S2 has been added to the leaching column, the buffer solution from step S4 is continued to be added to the leaching column through the peristaltic pump until leaching is complete (judgment criterion: the rare earth concentration in the leaching solution is below 0.03 g / L for three consecutive measurements).

[0039] Reference Figure 1 Effect test: Collect the leaching mother liquor and determine the concentration of rare earth and aluminum ions in it;

[0040] The results showed that the rare earth leaching rate was 92.3%, and the aluminum ion concentration in the leaching mother liquor was 26 mg / L, which was 74.2% lower than that of the traditional method (Comparative Example 1). Example

[0041] like Figure 2 As shown, a method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores comprises the following steps:

[0042] Step S1: Prepare the leaching agent:

[0043] Ammonium sulfate was used as the leaching agent. 19.8g of ammonium sulfate ((NH4)2SO4, purity ≥99%) was weighed, dissolved in deionized water and diluted to 1500mL to obtain an ammonium sulfate solution with a concentration of 0.1mol / L as the leaching agent.

[0044] Step S2: Prepare the composite leaching agent:

[0045] Add the buffer acetic acid-ammonium acetate to the ammonium sulfate solution in step S1: Weigh 37.6g of ammonium acetate (CH3COONH4, purity ≥99%) and 6.6mL of glacial acetic acid (purity ≥99.5%), add them to the above ammonium sulfate solution, and stir until completely dissolved to obtain a composite leaching agent with a total buffer concentration of 0.4mol / L and a pH value of 5.4 (monitor the pH in real time and fine-tune it to 4.8 using a pH meter).

[0046] Step S3: Leaching with composite leaching agent:

[0047] 5 kg of the same ion-adsorption rare earth ore as in Example 1 was selected and packed into a leaching column of the same specifications. The composite leaching agent from step S2 was added to the leaching column at a uniform rate using a peristaltic pump (flow rate 1.5 mL / min) for column leaching.

[0048] Step S4: Prepare the buffer solution:

[0049] Prepare a buffer solution using the buffer (acetic acid-ammonium acetate) from step S2: Weigh 75.2g of ammonium acetate and 13.2mL of glacial acetic acid, add deionized water to dissolve and bring the volume up to 3000mL to obtain a buffer solution with a total buffer concentration of 0.4mol / L and a pH value of 5.4 (verified with a pH meter).

[0050] Step S5: The ore is leached further with the buffer solution.

[0051] After the composite leaching agent is added, the buffer solution from step S4 is added again via a peristaltic pump until the rare earth concentration in the leaching solution is below 0.03 g / L for three consecutive times.

[0052] Reference Figure 1 Results test: The rare earth leaching rate was 91.5% (about 1% lower than the traditional method), and the aluminum ion concentration in the leaching mother liquor was 7 mg / L, which was 93% lower than the traditional method. Example

[0053] like Figure 2As shown, a method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores comprises the following steps:

[0054] Step S1: Prepare the leaching agent:

[0055] Sodium sulfate was used as the leaching agent. 28.4g of sodium sulfate (Na2SO4, purity ≥99%) was weighed, dissolved in deionized water and diluted to 1000mL to obtain a sodium sulfate solution with a concentration of 0.2mol / L as the leaching agent.

[0056] Step S2: Prepare the composite leaching agent:

[0057] Add the buffer sodium dihydrogen phosphate-sodium hydrogen phosphate to the sodium sulfate solution in step S1: Weigh 46.18g of sodium dihydrogen phosphate (NaH2PO4・2H2O, purity ≥99%) and 1.36g of disodium hydrogen phosphate (Na2HPO4・12H2O, purity ≥99%), add them to the above sodium sulfate solution, and stir until completely dissolved to obtain a composite leaching agent with a total buffer concentration of 0.3mol / L and a pH value of 5.3 (pH is monitored in real time and finely adjusted to 5.3 with a pH meter).

[0058] Step S3: Leaching with composite leaching agent:

[0059] Select 5 kg of the same ion-adsorption rare earth ore as in Example 1 and pack it into a leaching column of the same specifications; add the composite leaching agent from step S2 into the leaching column at a uniform rate and perform column leaching.

[0060] Step S4: Prepare the buffer solution:

[0061] Prepare a buffer solution using the buffer (sodium dihydrogen phosphate-sodium hydrogen phosphate) from step S2: Weigh 138.5g of sodium dihydrogen phosphate and 24.1g of disodium hydrogen phosphate, add deionized water to dissolve and bring the volume to 3000mL to obtain a buffer solution with a total buffer concentration of 0.3mol / L and a pH of 5.3.

[0062] Step S5: The ore is leached further with the buffer solution.

[0063] After the composite leaching agent is added, the buffer solution from step S4 is added again via a peristaltic pump until the rare earth concentration in the leaching solution is below 0.03 g / L for three consecutive times.

[0064] Reference Figure 1 Results testing showed that the rare earth leaching rate was 92.1%, and the aluminum ion concentration in the leaching mother liquor was 10 mg / L, which is 90% lower than that of the traditional method. Example

[0065] like Figure 2 As shown, a method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores comprises the following steps:

[0066] Step S1: Prepare the leaching agent:

[0067] A sodium sulfate solution with a concentration of 0.15 mol / L was prepared according to the method in Example 3, using sodium sulfate as the leaching agent.

[0068] Step S2: Prepare the composite leaching agent:

[0069] Add the buffer citric acid-sodium citrate to the sodium sulfate solution in step S1: Weigh 42g of citric acid monohydrate and 58.8g of sodium citrate dihydrate, add them to the sodium sulfate solution above, and stir until completely dissolved to obtain a composite leaching agent with a total buffer concentration of 0.2mol / L and a pH value of 5.0.

[0070] Step S3: Leaching with composite leaching agent:

[0071] 5 kg of the same ion-adsorption rare earth ore as in Example 1 was selected and packed into a leaching column of the same specifications. The composite leaching agent from step S2 was added to the leaching column at a uniform rate for column leaching.

[0072] Step S4: Prepare the buffer solution:

[0073] Prepare a buffer solution using the buffer (sodium dihydrogen phosphate-sodium hydrogen phosphate) from step S2: Weigh 126g of citric acid monohydrate and 176.4g of sodium citrate dihydrate, add deionized water to dissolve and bring the volume to 3000mL to obtain a buffer solution with a total buffer concentration of 0.2mol / L and a pH of 5.0.

[0074] Step S5: The ore is leached further with the buffer solution.

[0075] After the composite leaching agent is added, the buffer solution from step S4 is added again via a peristaltic pump until the rare earth concentration in the leaching solution is below 0.03 g / L for three consecutive times.

[0076] Reference Figure 1 Results testing showed that the rare earth leaching rate was 92.0%, and the aluminum ion concentration in the leaching mother liquor was 18 mg / L, which was 82% lower than that of the traditional method.

[0077] Comparative example:

[0078] The traditional method for leaching aluminum ions from rare earth ores involves the following steps:

[0079] Step 1: Prepare an ammonium sulfate solution with a concentration of 0.15 mol / L using ammonium sulfate as the leaching agent;

[0080] Step 2: Following the ore body loading method in Example 1, the above ammonium sulfate solution is added to the leaching column for column leaching using a peristaltic pump (flow rate 1.5 mL / min);

[0081] Step 3: Prepare an ammonium sulfate solution with a concentration of 0.04 mol / L. After the solution from Step 1 has been added, continue to add it to the leaching column using a peristaltic pump until the rare earth elements are completely leached.

[0082] Reference Figure 1 Effect test: The rare earth leaching rate was 92.5%, but the aluminum ion concentration in the leaching mother liquor was 101 mg / L, which was significantly higher than that in Examples 1-4 of this invention.

[0083] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications, improvements, and substitutions without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores, characterized in that, The steps are as follows: Step S1: Prepare the leaching agent according to the rare earth content in the ore body; Step S2: Add a buffer to step S1 to prepare a composite leaching agent; Step S3: Add the composite leaching agent from step S2 into the ore body for leaching; Step S4: Prepare a buffer solution with the same pH buffering capacity as the composite leaching agent using the buffer from step S2. Step S5: After the composite leaching agent in step S2 has been added, continue to add the buffer solution in step S4 to the ore body until the leaching is completed. The buffer includes one of the following: acetate-sodium acetate, acetate-ammonium acetate, sodium dihydrogen phosphate-sodium hydrogen phosphate, and citric acid-sodium citrate. By configuring a composite leaching agent containing a buffer, the pH value of the leachate during the leaching process can be controlled between 4.8 and 5.

4.

2. The method for suppressing the leaching of aluminum ions, an impurity, in ion-adsorption rare earth ores according to claim 1, characterized in that: The leaching agent includes one or more of sodium sulfate, magnesium sulfate, and ammonium sulfate.

3. The method for suppressing the leaching of aluminum ions from ion-adsorption rare earth ores according to claim 2, characterized in that: The concentration of the leaching agent is 0.1-0.2 mol / L.

4. The method for suppressing the leaching of aluminum ions from ion-adsorption rare earth ores according to claim 1, characterized in that: In step S2, when the buffer is acetic acid-sodium acetate, the composite leaching agent is prepared by adding sodium acetate and glacial acetic acid to the leaching agent solution.

5. The method for suppressing the leaching of aluminum ions from ion-adsorption rare earth ores according to claim 1, characterized in that: In step S2, when the buffer is acetic acid-ammonium acetate, the composite leaching agent is prepared by adding ammonium acetate and glacial acetic acid to the leaching agent solution.

6. The method for suppressing the leaching of aluminum ions from ion-adsorption rare earth ores according to claim 1, characterized in that: In step S4, the buffer solution is prepared by adding a corresponding buffer to a pure aqueous solution.

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