Method for reducing rare earth concentration in rare earth mother liquor
By optimizing the ratio of oxalic acid solution to rare earth feed solution and controlling the temperature in rare earth mother liquor, the rare earth element content in rare earth mother liquor was effectively reduced, solving the problem of high rare earth element content in rare earth mother liquor, improving production yield and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 中稀金龙(长汀)稀土有限公司
- Filing Date
- 2024-10-18
- Publication Date
- 2026-04-21
AI Technical Summary
Current technology still results in high rare earth element content in rare earth mother liquor. While increasing the amount of oxalic acid used can improve the recovery rate, it also increases costs and adds to the production burden.
By controlling the temperature and ratio of deionized water and oxalic acid solution in the reactor, co-current precipitation and room temperature aging are carried out to optimize the weight ratio of rare earth feed solution to oxalic acid solution, thereby effectively reducing the rare earth elements in the rare earth mother liquor.
The rare earth element content in the rare earth mother liquor is reduced to below 100 mg/L, which improves production yield and reduces production costs.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rare earth precipitation and utilization technology, specifically relating to a method for reducing the rare earth concentration in rare earth mother liquor. Background Technology
[0002] After extraction and separation, rare earth feed solutions typically form rare earth chlorides, rare earth nitrates, or rare earth sulfates, which are then used in the next production stage. Analysis shows that even after general oxalic acid precipitation, the rare earth content in the mother liquor still exceeds 100 mg / L. For high-value rare earth elements, further reducing the rare earth element content in the mother liquor is crucial.
[0003] Oxalic acid, as an auxiliary material, has been widely used for many years in the industrial process of rare earth precipitation. It is used to precipitate rare earth elements from rare earth solutions. In recent years, in order to improve the recovery rate of rare earth elements, many rare earth companies have chosen to increase the amount of oxalic acid used.
[0004] However, while recycling rare earth mother liquor can improve the recovery rate of rare earths, this practice also brings problems. It not only increases additional costs but may also place an extra burden on subsequent production processes. Summary of the Invention
[0005] The purpose of this invention is to overcome the defects of the prior art and provide a method for reducing the rare earth concentration in rare earth mother liquor.
[0006] The technical solution of the present invention is as follows:
[0007] A method for reducing the rare earth concentration in rare earth mother liquor includes the following steps:
[0008] (1) Add deionized water to the reactor and heat to 40-60℃;
[0009] (2) Add the rare earth element solution with a concentration of 1.3-1.8 mol / L and the oxalic acid solution with a concentration of 120-180 g / L produced by the upstream extraction process to the reaction vessel of step (1) for co-current precipitation for 20-30 min. The rare earth element solution contains soluble rare earth salts and is at room temperature. The temperature of the oxalic acid solution is 45-50℃. The weight ratio of oxalic acid in the added oxalic acid solution to rare earth element in the rare earth element solution is controlled to be 1.14-1.21:1.
[0010] The volume ratio of the above-mentioned deionized water to rare earth solution is 5-10:9-12;
[0011] (3) The material obtained in step (2) is aged at room temperature, and then discharged and washed to obtain rare earth mother liquor.
[0012] In a preferred embodiment of the present invention, in step (1), the deionized water is heated to 40-50°C.
[0013] In a preferred embodiment of the present invention, the concentration of the oxalic acid solution is 120-150 g / L.
[0014] In a preferred embodiment of the present invention, the volume ratio of the deionized water to the rare earth solution is 7-10:9-10.
[0015] In a preferred embodiment of the present invention, in step (2), the temperature of the oxalic acid solution is 50°C.
[0016] In a preferred embodiment of the present invention, in step (2), the weight ratio of oxalic acid in the added oxalic acid solution to rare earth elements in the rare earth solution is controlled to be 1.14-1.21:1.
[0017] In a preferred embodiment of the present invention, in step (1), the deionized water is heated to 40-50°C; in step (2), the temperature of the oxalic acid solution is 50°C.
[0018] More preferably, the concentration of the oxalic acid solution is 120-150 g / L.
[0019] More preferably, the volume ratio of the deionized water to the rare earth feed solution produced by the upstream extraction process is 7-10:9-10.
[0020] In a further preferred embodiment, in step (2), during the co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled to be 1.1-1.14:1 for any time within the first half of the co-current precipitation time, and the weight ratio of oxalic acid to rare earth elements is controlled to be 1.21-1.25:1 for any time within the second half of the co-current precipitation time.
[0021] The beneficial effects of this invention are: by effectively controlling the proportion of reactants and the precipitation temperature, the content of rare earth elements in the treated rare earth mother liquor is reduced to below 100 mg / L, thereby improving the production yield. Detailed Implementation
[0022] The technical solution of the present invention will be further explained and described below through specific embodiments.
[0023] Comparative Example 1
[0024] (1) Add 700L of deionized water to the reactor and heat to 45℃;
[0025] (2) 1m 3ErCl3 solution with a concentration of 1.73 mol / L and oxalic acid solution with a concentration of 150 g / L were added to the reactor in step (1) for co-current precipitation. The flow rate of ErCl3 solution was 1.6 m. 3 / L, temperature is room temperature, oxalic acid flow rate is 3.65m3 / h (stable), oxalic acid solution temperature is 50℃, and the weight ratio of oxalic acid in oxalic acid solution to Er in ErCl3 feed is 1.10:1;
[0026] (3) The material was then discharged and washed to obtain rare earth mother liquor. ICP test showed that the Er content of the rare earth mother liquor was 312 mg / L.
[0027] Example 1
[0028] (1) Add 1000L of deionized water to the reactor and heat to 50℃;
[0029] (2) 1m 3 TbCl3 solution (concentration 1.3 mol / L) and oxalic acid solution (concentration 120 g / L) were added to the reactor in step (1) for co-current precipitation for 20 min. The flow rate of TbCl3 solution was 2 m³ / min. 3 / h, temperature is room temperature; oxalic acid solution flow rate is (4.8±0.2) m³ / h. 3 / h (at the 10th minute of co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled at 1.12:1; at the 20th minute of co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled at 1.23:1), the temperature of the oxalic acid solution is 50℃, and the overall weight ratio of oxalic acid in the added oxalic acid solution to Tb in the TbCl3 feed solution is controlled at 1.21:1;
[0030] (3) The material obtained in step (2) is aged at room temperature for 30 minutes, and then discharged and washed to obtain rare earth mother liquor.
[0031] According to ICP testing, the Tb content of the rare earth mother liquor was 34.1 mg / L.
[0032] Example 2
[0033] (1) Add 1000L of deionized water to the reactor and heat to 40℃;
[0034] (2) 0.9m 3 DyCl3 solution (concentration 1.72 mol / L) and oxalic acid solution (concentration 150 g / L) were added to the reactor in step (1) for co-current precipitation for 30 min. The flow rate of DyCl3 solution was 2 m. 3 The flow rate of the oxalic acid solution was (3.6 ± 0.2) m³ / h at room temperature. 3 / h (at the 10th minute of co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled at 1.13:1; at the 17th minute of co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled at 1.23:1), the temperature of the oxalic acid solution is 50℃, and the overall weight ratio of oxalic acid in the added oxalic acid solution to Dy in the DyCl3 feed solution is controlled at 1.20:1;
[0035] (3) The material obtained in step (2) is aged at room temperature for 10 minutes, and then discharged and washed to obtain rare earth mother liquor.
[0036] According to ICP testing, the Dy content of this rare earth mother liquor is 86.5 mg / L.
[0037] Example 3
[0038] (1) Add 700L of deionized water to the reactor and heat to 45℃;
[0039] (2) 1m 3 ErCl3 feed solution (concentration 1.73 mol / L) and oxalic acid solution (concentration 150 g / L) were added to the reactor of step (1) for co-current precipitation for 30 min. The flow rate of ErCl3 feed solution was 1.6 m. 3 / L, temperature is room temperature, and the flow rate of oxalic acid solution is (3.65±0.2)m. 3 / h (at the 15th minute of co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled at 1.11:1; at the 27.5th minute of co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled at 1.24:1), the temperature of the oxalic acid solution is 50℃, and the overall weight ratio of oxalic acid in the added oxalic acid solution to Er in the ErCl3 feed solution is controlled at 1.14:1;
[0040] (3) The material obtained in step (2) is aged at room temperature for 10 minutes, and then discharged and washed to obtain rare earth mother liquor.
[0041] According to ICP testing, the Er content of the rare earth mother liquor was 78.6 mg / L.
[0042] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.
Claims
1. A method for reducing the rare earth concentration in rare earth mother liquor, characterized in that: Includes the following steps: (1) Add deionized water to the reactor and heat to 40-60℃; (2) Add the rare earth feed solution with a concentration of 1.3-1.8 mol / L and the oxalic acid solution with a concentration of 120-180 g / L generated by the upstream extraction process to the reaction vessel of step (1) for co-current precipitation for 20-30 min. The rare earth feed solution contains soluble rare earth salts and is at room temperature. The temperature of the oxalic acid solution is 45-50℃. The weight ratio of oxalic acid in the added oxalic acid solution to rare earth elements in the rare earth feed solution is controlled to be 1.14-1.21:
1. The volume ratio of the above-mentioned deionized water to rare earth solution is 5-10:9-12; (3) The material obtained in step (2) is aged at room temperature, and then discharged and washed to obtain rare earth mother liquor.
2. The method as described in claim 1, characterized in that: In step (1), the deionized water is heated to 40-50°C.
3. The method as described in claim 1, characterized in that: The concentration of the oxalic acid solution is 120-150 g / L.
4. The method as described in claim 1, characterized in that: The volume ratio of the deionized water to the rare earth solution is 7-10:9-10.
5. The method as described in claim 1, characterized in that: In step (2), the temperature of the oxalic acid solution is 50°C.
6. The method as described in claim 1, characterized in that: In step (2), the weight ratio of oxalic acid in the added oxalic acid solution to rare earth elements in the rare earth solution is controlled to be 1.14-1.21:
1.
7. The method as described in claim 1, characterized in that: In step (1), the deionized water is heated to 40-50°C; in step (2), the temperature of the oxalic acid solution is 50°C.
8. The method as described in claim 7, characterized in that: The concentration of the oxalic acid solution is 120-150 g / L.
9. The method as described in claim 8, characterized in that: The volume ratio of the deionized water to the rare earth solution is 7-10:9-10.
10. The method as described in claim 9, characterized in that: In step (2), during the co-current precipitation, the weight ratio of oxalic acid to rare earth elements is controlled to be 1.1-1.14:1 for any time within the first half of the co-current precipitation time, and the weight ratio of oxalic acid to rare earth elements is controlled to be 1.21-1.25:1 for any time within the second half of the co-current precipitation time.