Method for selectively leaching enrichment containing rare earth

Abstract

The invention provides a method for selectively leaching a rare earth-containing enriched product, which comprises the following steps: mixing the rare earth-containing enriched product with an organic acid solution for leaching, and carrying out solid-liquid separation to obtain leaching residues and a leaching solution; the volume-mass ratio of the organic acid solution to the rare earth-containing enriched product is 3-10 mL / g, and the pH value of the leachate is controlled to be greater than or equal to 4.8 in the leaching process; the organic acid is formic acid or acetic acid. According to the method, selective leaching of the enrichment containing the rare earth can be completed only by using the formic acid or acetic acid solution, the leaching rate of the rare earth elements is high, the leachate only contains a small amount of impurities such as Al, Fe and Si, the subsequent impurity removal procedure is omitted, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of rare earth hydrometallurgy and relates to a method for selectively leaching rare earth-containing enriched materials. Background Art

[0002] Rare earth elements are widely used in permanent magnetic materials, alloy machinery, petrochemicals and other fields due to their unique optical, electrical and magnetic properties. They are indispensable in high-tech fields such as information, communications, aerospace, and national defense, and are regarded as strategic resources by many countries. my country has large reserves of rare earth resources and a wide range of categories. In particular, the southern ionic rare earth ores are easy to mine and have a high content of heavy rare earths, occupying an important position in the world rare earth market. The rare earth ions in the southern ionic rare earth ores are mainly adsorbed on the surface or lattice of clay minerals in the form of hydrated ions or hydroxyl hydrated ions, which can be used to remove the rare earth ions. + NH4 + Mg 2+ The rare earth elements are extracted by MgSO4, among which MgSO4 has the best effect. Then magnesium oxide or calcium oxide is used for precipitation to obtain rare earth enriched products. In this process, impurities such as Al and Fe in the ore will be leached out at the same time, and then enter into the sulfuric acid leaching solution with the leaching, affecting the subsequent extraction and separation.

[0003] At present, the commonly used impurity removal methods in industry are to add alkaline substances to adjust the pH so that the impurities form precipitation, or to separate them by extraction. CN116676479A uses sodium hydroxide to stir and wash the rare earth enriched material, and Al 3+ Transformed into AlO 2- , the washing liquid is recycled, and when the aluminum ion reaches a certain concentration, CO2 is used to make NaAlO2 - It turns into Al(OH)3 precipitation. This process can obtain rare earth concentrate with a purity of 95.70wt%. CN116136001A uses carboxylic acid type extractant to achieve the removal of Al in rare earth leaching mother liquor and the enrichment of rare earth.

[0004] In the process of adding alkaline substances to remove impurities, the amount of alkali consumed is large, and impurities such as Al, Fe, and Si will form co-precipitations, resulting in serious loss of rare earths. It is also easy to form colloids, which are difficult to filter. In the process of extraction and impurity removal, the loss of extractant is large, the number of extraction stages is large, and the efficiency is low. Therefore, a new method for extracting and separating rare earths is still needed to achieve efficient separation of rare earths and impurities. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a method for selective leaching of rare earth enriched materials. The method can complete the selective leaching of rare earth enriched materials using only formic acid or acetic acid solution, has a high leaching rate of rare earth elements, and contains only a small amount of Al, Fe, and Si impurities in the leachate. Compared with the currently used sulfuric acid leaching process, the impurity content is low, the subsequent impurity removal and solid-liquid separation steps are reduced, the operation is simple, and it is suitable for industrial production.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for selectively leaching a rare earth-containing enrichment, the method comprising:

[0008] The enriched material containing iron, aluminum, magnesium, silicon and rare earth elements is mixed with an organic acid solution for leaching, and a leaching residue and a leaching solution are obtained after solid-liquid separation;

[0009] The volume mass ratio of the organic acid solution to the rare earth-containing concentrate is 3-10 mL / g, and the pH of the leaching solution is controlled to be ≥4.8 during the leaching process;

[0010] The organic acid is formic acid or acetic acid.

[0011] The mass volume ratio may be 3 mL / g, 4 mL / g, 5 mL / g, 6 mL / g, 7 mL / g, 8 mL / g, 9 mL / g or 10 mL / g, etc., and the pH may be 4.8, 4.9, 5, 5.2, 5.5 or 6, etc., but are not limited to the listed values, and other values ​​not listed within the above ranges are also applicable. The pH of the leachate is preferably pH ≥ 5.

[0012] In the present invention, since the rare earth enrichment contains impurities such as magnesium, iron, and aluminum, after iron and aluminum are mixed with acetic acid or formic acid, a complex of acetic acid or formic acid and metal is generated. Since rare earth elements and magnesium are leached preferentially, the leaching parameters are controlled to achieve selective leaching of iron, aluminum, and rare earth elements. Moreover, in the acetic acid system, when the leaching end point pH is controlled to be ≥4.8, aluminum and iron are converted into more insoluble compounds, so that the rare earth leaching rate reaches more than 99%, while the leaching rate of iron and aluminum is lowered.

[0013] In the present invention, the rare earth-containing enriched product may be an ionic ore leaching solution, a magnesium oxide precipitate enriched product, and the like.

[0014] As a preferred technical solution of the present invention, the rare earth element content in the rare earth enriched material is 10-80wt%, the iron content is 1-5wt%, the aluminum content is 4-15wt%, the magnesium content is 5-50wt%, and the silicon content is 7-15wt%. Among them, the content of rare earth elements can be 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt% or 80wt%, etc., the content of iron can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%, etc., and the content of aluminum can be 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt% , 13wt%, 14wt% or 15wt%, etc., the magnesium content can be 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, etc., the silicon content can be 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical ranges are equally applicable.

[0015] In the present invention, the rare earth-containing concentrate may contain a very small amount of other metals and / or non-metallic elements in addition to rare earth elements, iron, aluminum, magnesium and silicon. However, due to their small content, they will not generally affect the leaching effect of rare earth elements, so the specific types and contents of other metals and / or non-metallic elements are not specifically limited.

[0016] As a preferred technical solution of the present invention, the concentration of the organic acid solution is 5 to 40wt%, such as 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt% or 40wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] As a preferred technical solution of the present invention, the molar ratio of the rare earth element in the rare earth enriched material to the organic acid in the organic acid solution is 1:5 to 10, such as 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] As a preferred technical solution of the present invention, the leaching temperature is 40-80°C, such as 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] As a preferred technical solution of the present invention, the leaching time is 5 to 90 min, such as 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] As a preferred technical solution of the present invention, the iron content in the leaching solution is ≤80ppm, the aluminum content is ≤350ppm, and the silicon content is ≤50ppm.

[0021] As a preferred technical solution of the present invention, the concentration of rare earth elements in the leachate is 10 to 80 g / L, such as 10 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 75 g / L or 80 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] As a preferred technical solution of the present invention, the rare earth element content in the leached residue is less than 0.1wt%.

[0023] As a preferred technical solution of the present invention, the method for selective leaching of rare earth-containing enriched materials comprises:

[0024] The rare earth-enriched material having a rare earth element content of 10 to 80 wt% is mixed with a formic acid or acetic acid solution having a concentration of 5 to 40 wt% at a volume mass ratio of 3 to 10 mL / g, and leached at 40 to 80° C. for 5 to 90 min, wherein the pH of the leaching solution is controlled to be ≥ 4.8 during the leaching process, and a leaching residue and a leaching solution are obtained after solid-liquid separation;

[0025] The iron content in the leaching solution is ≤80ppm, the aluminum content is ≤350ppm, the silicon content is ≤50ppm, and the concentration of rare earth elements is 10-80g / L;

[0026] The leaching rate of the rare earth is greater than 99%, and the content of the rare earth elements in the leached residue is less than 0.1wt%.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] (1) The present invention provides a method for selectively leaching rare earth-enriched materials, which can complete the selective leaching of rare earth-enriched materials using only formic acid or acetic acid solution, and the leachate contains only a small amount of Al, Fe, and Si impurities, and the leaching rate of rare earth elements is high;

[0029] (2) The present invention provides a method for selectively leaching rare earth-containing enriched materials, which reduces the subsequent impurity removal and solid-liquid separation steps, is simple to operate, and is suitable for industrial production. DETAILED DESCRIPTION

[0030] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0031] Example 1

[0032] This embodiment provides a method for leaching and extracting a rare earth-containing enriched substance, the method comprising the following steps:

[0033] A rare earth enriched material (2wt% Fe, 15wt% Al, 50wt% Mg, 5wt% Si) containing 18wt% of rare earth elements was stirred and mixed with an acetic acid solution of concentration 10wt% at a volume-to-mass ratio of 6ml / g. The mixture was leached at 60°C for 30min. The pH of the leaching solution was controlled to be 4.8 during the leaching process. After solid-liquid separation, 21.96g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 60.39ppm, 287.65ppm and 43.34ppm, respectively. The leaching rate of rare earth elements was 99.98%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si. The content of rare earth elements in the residue was less than 0.1wt%.

[0034] Example 2

[0035] This embodiment provides a method for selectively leaching a rare earth-containing concentrate, the method comprising the following steps:

[0036] A rare earth enrichment (5wt% Fe, 10wt% Al, 45wt% Mg, 10wt% Si) containing 30wt% of rare earth elements was stirred and mixed with an acetic acid solution with a concentration of 20wt% at a volume-to-mass ratio of 5ml / g. The mixture was leached at 80°C for 30min. The pH of the leaching solution was controlled to be greater than 4.8 during the leaching process. After solid-liquid separation, 42.68g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 43.32ppm, 265.37ppm and 34.84ppm, respectively. The leaching rate of rare earth elements was 99.99%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si, and the content of rare earth elements in the residue was less than 0.1wt%.

[0037] Example 3

[0038] This embodiment provides a method for selectively leaching a rare earth-containing concentrate, the method comprising the following steps:

[0039] A rare earth enriched material (5wt% Fe, 15wt% Al, 5wt% Mg, 15wt% Si) containing 60wt% of rare earth elements was stirred and mixed with an acetic acid solution with a concentration of 20wt% at a volume-to-mass ratio of 10ml / g. The mixture was leached at 80°C for 60min. The pH of the leaching solution was controlled to be greater than 4.8 during the leaching process. After solid-liquid separation, 43.54g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 24.84ppm, 202.32ppm and 27.68ppm, respectively. The leaching rate of rare earth elements was 99.99%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si. The content of rare earth elements in the residue was less than 0.1wt%.

[0040] Example 4

[0041] This embodiment provides a method for selectively leaching a rare earth-containing concentrate, the method comprising the following steps:

[0042] A rare earth enriched material containing 10wt% of rare earth elements (5wt% Fe, 15wt% Al, 50wt% Mg, 15wt% Si, and other elements totaling 5wt%) was stirred and mixed with a 5wt% acetic acid solution at a volume mass ratio of 10ml / g, and leached at 80°C for 45min. During the leaching process, the pH of the leaching solution was controlled to be greater than 4.8. After solid-liquid separation, 10.0g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al, and Si in the leaching solution were 48.68ppm, 256.92ppm, and 33.64ppm, respectively. The leaching rate of rare earth elements was 99.97%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe, and Si, and the content of rare earth elements in the residue was less than 0.1wt%.

[0043] Example 5

[0044] This embodiment provides a method for selectively leaching a rare earth-containing concentrate, the method comprising the following steps:

[0045] A rare earth enrichment (1wt% Fe, 4wt% Al, 8wt% Mg, 7wt% Si) containing 80wt% of rare earth elements was stirred and mixed with an acetic acid solution of 40wt% in a volume-to-mass ratio of 10ml / g. The mixture was leached at 80°C for 90min. The pH of the leaching solution was controlled to be greater than 4.8 during the leaching process. After solid-liquid separation, 80.0g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 77.31ppm, 336.29ppm and 48.87ppm, respectively. The leaching rate of rare earth elements was 99.98%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si. The content of rare earth elements in the residue was less than 0.1wt%.

[0046] Example 6

[0047] This embodiment provides a method for selectively leaching a rare earth-containing concentrate, the method comprising the following steps:

[0048] A rare earth enriched material (3wt% Fe, 12wt% Al, 42wt% Mg, 8wt% Si) containing 35wt% of rare earth elements was stirred and mixed with a formic acid solution with a concentration of 15wt% at a volume-to-mass ratio of 7ml / g. The mixture was leached at 60°C for 90min. The pH of the leaching solution was controlled to be greater than 4.8 during the leaching process. After solid-liquid separation, 33.54g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 30.23ppm, 150.81ppm and 18.39ppm, respectively. The leaching rate of rare earth elements was 99.97%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si. The content of rare earth elements in the residue was less than 0.1wt%.

[0049] Example 7

[0050] This embodiment provides a method for selectively leaching a rare earth-containing concentrate, the method comprising the following steps:

[0051] A rare earth enriched material (4wt% Fe, 11wt% Al, 30wt% Mg, 10wt% Si) containing 45wt% of rare earth elements was stirred and mixed with a formic acid solution with a concentration of 25wt% at a volume-to-mass ratio of 6ml / g. The mixture was leached at 40°C for 15min. The pH of the leaching solution was controlled to be greater than 4.8 during the leaching process. After solid-liquid separation, 75.83g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 77.95ppm, 335.63ppm and 42.84ppm, respectively. The leaching rate of rare earth elements was 99.99%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si. The content of rare earth elements in the residue was less than 0.1wt%.

[0052] Comparative Example 1

[0053] This comparative example provides a method for selectively leaching a rare earth-containing enrichment, the method comprising the following steps:

[0054] A rare earth enriched material (2wt% Fe, 15wt% Al, 50wt% Mg, 5wt% Si) containing 18wt% of rare earth elements was stirred and mixed with a 10wt% sulfuric acid solution at a volume-to-mass ratio of 3ml / g. The mixture was leached at 40°C for 15min. After solid-liquid separation, 21.88g / L rare earth sulfate leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 450.30ppm, 1295.52ppm and 259.36ppm, respectively. The leaching rate of rare earth elements was 99.98%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe, Si, and the content of rare earth elements in the residue was less than 0.1wt%.

[0055] Compared with the embodiments, although the leaching rate of rare earth elements in this comparative example can reach 99.98%, its selectivity is relatively low, resulting in a higher impurity content in the leachate. The contents of Fe, Al and Si in the leachate are all higher than those in the embodiments.

[0056] Comparative Example 2

[0057] This comparative example provides a method for selectively leaching a rare earth-containing enrichment, the method comprising the following steps:

[0058] A rare earth enriched material (5wt% Fe, 10wt% Al, 45wt% Mg, 10wt% Si) containing 30wt% of rare earth elements was stirred and mixed with an acetic acid solution with a concentration of 20wt% at a volume mass ratio of 5ml / g. The mixture was leached at 25°C for 30min. After solid-liquid separation, 42.68g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 369.96ppm, 1025.35ppm and 163.28ppm, respectively. The leaching rate of rare earth elements was 99.99%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si.

[0059] Compared with the embodiments, the leaching temperature of this comparative example is only 25°C. Although the leaching rate of rare earth elements can reach 99.99%, the contents of Fe, Al and Si in the leachate are relatively high. The reason is that in the leaching process, there are dissolution processes of rare earth and impurity ions and hydrolysis processes of Al and Fe impurities to generate precipitation. At a lower temperature, the hydrolysis rate of Fe and Al is slower, and the precipitation generated by the dissolved impurity ions is less, showing a high impurity content in the leachate.

[0060] Comparative Example 3

[0061] This comparative example provides a method for selectively leaching a rare earth-containing enrichment, the method comprising the following steps:

[0062] A rare earth enriched material (5wt% Fe, 15wt% Al, 5wt% Mg, 15wt% Si) containing 60wt% of rare earth elements was stirred and mixed with an acetic acid solution with a concentration of 20wt% at a volume-to-mass ratio of 15ml / g. The mixture was leached at 80°C for 60min. The pH of the leaching solution was controlled to be less than 4.8 during the leaching process. After solid-liquid separation, 43.50g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al and Si in the leaching solution were 105.32ppm, 886.54ppm and 65.93ppm, respectively. The leaching rate of rare earth elements was 99.99%. The leaching residue was mainly composed of unreacted impurities such as Al, Fe and Si. The content of rare earth elements in the residue was less than 0.1wt%.

[0063] Compared with the embodiments, the mass volume ratio of the acetic acid solution and the rare earth concentrate in this comparative example is relatively high, resulting in an increased impurity leaching rate. The contents of Fe, Al and Si in the leachate are 105.32 ppm, 886.55 ppm and 65.94 ppm, respectively, and the contents of Fe, Al and Si are all higher than those in the embodiments.

[0064] Comparative Example 4

[0065] This comparative example provides a method for selectively leaching a rare earth-containing enrichment, the method comprising the following steps:

[0066] A rare earth enriched material containing 10wt% of rare earth elements (5wt% Fe, 15wt% Al, 50wt% Mg, 15wt% Si, and other elements totaling 5wt%) was stirred and mixed with an acetic acid solution of 10wt% at a volume-to-mass ratio of 2ml / g. The mixture was leached at 80°C for 45min. The pH of the leaching solution was controlled to be greater than 4.8 during the leaching process. After solid-liquid separation, 7.32g / L acetic acid rare earth leaching solution and leaching residue were obtained. The mass contents of Fe, Al, and Si in the leaching solution were 20.31ppm, 156.35ppm, and 18.92ppm, respectively. The leaching rate of rare earth elements was 69.39%. In addition to unreacted impurities such as Al, Fe, and Si, the leaching residue also contained some rare earths. The content of rare earth elements in the leaching residue was 3.06wt%.

[0067] Compared with the embodiments, the comparative example has a relatively low volume mass ratio of the acetic acid solution and the rare earth concentrate, resulting in a reduced leaching rate of the rare earth elements, which is only 69.39%.

[0068] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for selective leaching of rare earth-containing concentrates, characterized in that: The method comprises: The enriched material containing iron, aluminum, magnesium, silicon and rare earth elements is mixed with an organic acid solution for leaching, and a leaching residue and a leaching solution are obtained after solid-liquid separation; The volume mass ratio of the organic acid solution to the rare earth-containing concentrate is 3-10 mL / g, and the pH of the leaching solution is controlled to be ≥4.8 during the leaching process; The organic acid is formic acid or acetic acid.

2. The method according to claim 1, characterized in that: The rare earth enriched material contains 10-80wt% rare earth elements, 1-5wt% iron, 4-15wt% aluminum, 5-50wt% magnesium and 7-15wt% silicon.

3. The method according to claim 1, characterized in that: The concentration of the organic acid solution is 5-40 wt %.

4. The method according to claim 1, characterized in that The molar ratio of the rare earth element in the rare earth-containing concentrate to the organic acid in the organic acid solution is 1:5-10.

5. The method according to claim 1, characterized in that The leaching temperature is 40-80°C.

6. The method according to claim 1, characterized in that The leaching time is 5 to 90 minutes.

7. The method according to claim 1, characterized in that The iron content in the leaching solution is ≤80 mg / L, the aluminum content is ≤350 mg / L, and the silicon content is ≤50 mg / L.

8. The method according to claim 1, characterized in that The concentration of rare earth elements in the leaching solution is 10-80 g / L.

9. The method according to claim 1, characterized in that: The rare earth element content in the leached residue is less than 0.1wt%.

10. A method for selective leaching of rare earth-containing concentrates according to any one of claims 1 to 9, characterized in that: The method comprises: The rare earth-enriched material having a rare earth element content of 10 to 80 wt% is mixed with a formic acid or acetic acid solution having a concentration of 5 to 40 wt% at a volume mass ratio of 3 to 10 mL / g, and leached at 40 to 80° C. for 5 to 90 min, wherein the pH of the leaching solution is controlled to be ≥ 4.8 during the leaching process, and a leaching residue and a leaching solution are obtained after solid-liquid separation; The iron content in the leaching solution is ≤80ppm, the aluminum content is ≤350ppm, the silicon content is ≤50ppm, and the concentration of rare earth elements is 10-80g / L; The rare earth element content in the leached residue is less than 0.1wt%.