Method for extracting rare earth from rare earth enrichment

Abstract

The invention relates to a method for extracting rare earth from a rare earth enriched product, which utilizes the characteristic that rare earth and magnesium hydroxide are easy to leach from organic acid, and then utilizes the extraction characteristics of rare earth and magnesium in organic acid and acidic phosphorus type extractant, so that extraction can be realized without saponification, and meanwhile, the organic acid is recycled; by utilizing the characteristic that the separation effect of rare earth and magnesium in an organic acid system is good, preparation and recycling of magnesium salt can be realized; according to the method, waste salt, waste water and waste gas are not generated in the process from leaching to rare earth extraction and enrichment and impurity separation, the technological process is short, operation is easy, the equipment requirement is low, and meanwhile popularization is easy.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth recovery, and in particular to a method for extracting rare earth from rare earth enriched materials. Background Art

[0002] Rare earth elements consist of scandium, yttrium and 15 lanthanide elements. Due to their unique optical, electrical and magnetic properties, rare earth elements are currently widely used in various functional materials, steel, non-ferrous metals and other fields. In addition, rare earths have also shown great potential in emerging fields such as medical imaging, molecular magnetism, chemical biology, etc. Among them, medium and heavy rare earths are particularly widely used, and the high grade of medium and heavy rare earths in southern ionic minerals is the main source of medium and heavy rare earths.

[0003] Rare earth leaching from ionic ores usually uses magnesium oxide precipitation, hydrochloric acid or sulfuric acid leaching, carbonate precipitation, and then dissolution extraction; or phosphoric acid extractant is used to directly extract ion mine leachate. However, the amount of mine leachate required for each ton of rare earth is as high as tens of thousands of tons, and the consumption of extractants is huge.

[0004] CN 114015900A discloses a method for enriching rare earth from rare earth leaching mother liquor, using sulfosalicylic acid and / or acetylacetone as an impurity suppressant, using the impurity suppressant to form a complex with iron and aluminum impurities in the leaching mother liquor, while the rare earth still exists in the leaching mother liquor in the form of ions, and when adsorbed by ion exchange resin, the rare earth element is adsorbed on the resin, while the complex formed by iron, aluminum and the impurity suppressant remains in the solution, and then the loaded resin is eluted with an impurity suppressant solution to remove a small amount of iron and aluminum ions adsorbed in the resin, and then an acid solution is used to desorb the rare earth in the resin, so that a high-purity rare earth enriched solution can be obtained. However, the invention uses resin to adsorb rare earth, the rare earth adsorption amount is small, and the production cost is high.

[0005] CN 102190325A discloses a method for recovering rare earths from ionic rare earth ore. The method uses at least one of magnesium sulfate, magnesium chloride and calcium chloride as a leaching agent to replace most or even all of ammonium sulfate, ammonium chloride or sodium chloride to leach the ionic rare earth ore. The obtained rare earth leaching solution is neutralized and impurities are removed, and then magnesium bicarbonate and / or calcium bicarbonate solution are used to precipitate the rare earth to obtain a rare earth carbonate product.

[0006] CN 116676479A discloses a method for recovering rare earth and aluminum from ionic rare earth leachate, wherein the ionic rare earth leachate is used as a raw material, and rare earth and aluminum are completely precipitated by magnesium oxide and magnesium bicarbonate in a step-by-step precipitation manner, while most of the silicon remains in the solution; the enriched product is then stirred and washed with sodium hydroxide, and the aluminum hydroxide therein is converted into sodium aluminate and introduced into the solution, and the basic rare earth sulfate is converted into rare earth hydroxide and sulfate ions are also released, and finally rare earth hydroxide is obtained. The mother liquor after impurities removal is carbonized and precipitated by carbon dioxide to obtain aluminum hydroxide.

[0007] The above method has prominent problems such as a long process flow, incomplete reuse of magnesium salts, low rare earth recovery efficiency, large wastewater discharge, or high costs, which restricts the development of rare earth separation and recovery technologies.

[0008] Therefore, in view of the deficiencies of the existing technology, it is necessary to provide a method for extracting rare earths with a short process flow, low cost, no waste salts or wastewater generated, and capable of realizing the cyclic reuse of organic acids and magnesium salts. Summary of the Invention

[0009] The object of the present invention is to provide a method for extracting rare earths from rare earth enriched materials, which realizes the cyclic reuse of organic acids and magnesium salts. At the same time, the extraction process does not require saponification, the process is green and environmentally friendly, and no waste gas or wastewater is generated; the production cost is low, which is convenient for the separation and utilization of rare earths.

[0010] To achieve the object of the present invention, the following technical solutions are adopted:

[0011] The present invention provides a method for extracting rare earths from rare earth enriched materials, and the method comprises the following steps:

[0012] (1) Uniformly mix the rare earth enriched material with the organic acid solution, and after solid-liquid separation, obtain a leaching solution and a residue;

[0013] (2) Mix an acidic phosphorus extractant with the leaching solution obtained in step (1) to obtain a rare earth-loaded organic phase and a raffinate; the obtained rare earth-loaded organic phase is subjected to extraction separation to obtain a magnesium-loaded organic phase and a rare earth-loaded organic phase; the obtained raffinate is subjected to impurity removal treatment and then recycled to step (1);

[0014] (3) The magnesium-loaded organic phase obtained in step (2) is subjected to back-extraction treatment to obtain a magnesium salt solution and an organic phase; the obtained magnesium salt solution is used for mine leaching, and the obtained organic phase is recycled to the mixing in step (2).

[0015] The method for extracting rare earths from rare earth enriched materials provided by the present invention utilizes the fact that rare earths and magnesium hydroxides are easily leached from organic acids, and then uses the extraction characteristics of rare earths and magnesium in organic acids and acidic phosphorus extractants to achieve extraction without saponification, and at the same time realizes the reuse of organic acids; utilizes the characteristic that the separation effect of rare earths and magnesium in the organic acid system is good to realize the preparation and reuse of magnesium salts; this process does not generate waste salts, wastewater, or waste gas from the leaching to the extraction and enrichment of rare earths and the separation from impurities, has a short process flow, is simple to operate, has low equipment requirements, and is easy to promote.

[0016] Preferably, the rare earth concentrate in step (1) comprises any one of rare earth minerals, precipitates of ionic ore leaching solutions, rare earth waste or precipitates of rare earth waste leaching solutions, or a combination of at least two of them. Typical but non-limiting combinations include a combination of rare earth minerals and precipitates of ionic ore leaching solutions, a combination of rare earth waste and precipitates of rare earth waste leaching solutions, or a combination of rare earth minerals, precipitates of ionic ore leaching solutions, rare earth waste and precipitates of rare earth waste leaching solutions.

[0017] Preferably, the rare earth content in the rare earth concentrate in step (1) is 10-95%, and the magnesium content is 10-40%.

[0018] The rare earth content in the rare earth enriched material is 10-95%, for example, it can be 10%, 30%, 50%, 70% or 95%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0019] The magnesium content in the rare earth concentrate is 10-40%, for example, 10%, 20%, 30% or 40%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the organic acid in the organic acid solution of step (1) comprises any one of acetic acid, propionic acid or lauric acid, or a combination of at least two of them. Typical but non-limiting combinations include a combination of acetic acid and propionic acid, a combination of acetic acid and lauric acid, or a combination of acetic acid, propionic acid and lauric acid.

[0021] Preferably, the volume concentration of the organic acid in the organic acid solution in step (1) is 5-50%, for example, 5%, 10%, 20%, 30% or 50%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] In the present invention, organic acid is used to leach rare earth enriched materials, so that the extractant does not need to be saponified. In the organic acid extraction, the organic acid reacts with metal ions in the form of monomers, the utilization rate of the extractant is increased, and the utilization rate of one extraction can reach 30%. At the same time, the organic acid can be reused. In the organic acid system, the valence states of rare earth and magnesium are different, so the rare earth and magnesium can be completely separated. The magnesium salt can be reused for leaching rare earth in the mine, and the reused magnesium salt does not contain ammonia nitrogen compared with the magnesium salt reused in the existing process for extracting rare earth from mine enriched materials.

[0023] Preferably, the mass volume ratio of the rare earth enriched material to the organic acid solution in step (1) is 1g:(2-10)mL, for example, it can be 1g:2mL, 1g:4mL, 1g:6mL, 1g:8mL or 1g:10mL, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0024] The mass volume ratio of the rare earth concentrate to the organic acid solution must be limited to a reasonable range. If the mass volume ratio is too high, the rare earth and magnesium cannot be fully leached; if the mass volume ratio is too low, it is not conducive to the subsequent extraction process.

[0025] Preferably, the acidic phosphorus-type extractant in step (2) includes any one of P204, P507 or C272 or a combination of at least two of them. Typical but non-limiting combinations include a combination of P204 and P507, a combination of P507 and C272, or a combination of P204, P507 and C272.

[0026] Preferably, the molar ratio of the acidic phosphorus-type extractant in step (2) to the rare earth in the leaching solution is (3-10):1, for example, it can be 3:1, 5:1, 7:1, 8:1 or 10:1, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the extractive separation in step (2) comprises countercurrent extraction or fractional extraction.

[0028] After the impurity removal treatment in step (2), the raffinate is converted into a single organic acid solution, which can be reused in step (1).

[0029] Preferably, the stripping treatment in step (3) is carried out using a sulfuric acid solution.

[0030] Preferably, the concentration of the sulfuric acid solution in step (3) is 6-8 mol / L, for example, 6 mol / L, 6.5 mol / L, 7 mol / L, 7.5 mol / L or 8 mol / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the magnesium salt solution in step (3) comprises magnesium sulfate solution.

[0032] By using a sulfuric acid solution to strip the magnesium-loaded organic phase, a magnesium sulfate solution and an organic phase can be obtained. The magnesium sulfate solution can be reused for mine leaching, and the organic phase can be reused in step (2) as an acidic phosphorus-type extractant, thereby realizing the recycling of magnesium salt and organic phase without generating waste salt or waste liquid.

[0033] As a preferred technical solution of the method of the present invention, the method comprises the following steps:

[0034] (1) uniformly mixing a rare earth enriched material having a rare earth content of 10-95% and a magnesium content of 10-40% and an organic acid solution having an organic acid volume concentration of 5-50%, and obtaining a leachate and a residue after solid-liquid separation; the mass volume ratio of the rare earth enriched material to the organic acid solution is 1 g: (2-10) mL;

[0035] (2) mixing an acidic phosphorus-based extractant with the leaching solution obtained in step (1) to obtain a rare earth-containing loaded organic phase and a raffinate; the molar ratio of the acidic phosphorus-based extractant to the rare earth in the leaching solution is (3-10):1; subjecting the obtained rare earth-containing loaded organic phase to countercurrent extraction or fractional extraction to obtain a magnesium-loaded organic phase and a rare earth-loaded organic phase; and the obtained raffinate is subjected to impurity removal treatment and then reused in step (1);

[0036] (3) The magnesium-loaded organic phase obtained in step (2) is subjected to back extraction treatment with a sulfuric acid solution having a concentration of 6-8 mol / L to obtain a magnesium sulfate solution and an organic phase; the obtained magnesium sulfate solution is used for mine leaching, and the obtained organic phase is returned to the mixing described in step (2).

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The method for extracting rare earth from rare earth enriched materials provided by the present invention utilizes that rare earth and magnesium hydroxide are easy to be leached from organic acid, then utilizes the extraction characteristics of rare earth and magnesium in organic acid and acidic phosphorus type extractant, realizes extraction without saponification, and realizes the recycling of organic acid at the same time; utilizes the characteristic of good separation effect of rare earth and magnesium in organic acid system, can realize the preparation and recycling of magnesium salt; the process from leaching to extraction and enrichment of rare earth and separation from impurities does not generate waste salt, waste water and waste gas, has short process flow, simple operation, low equipment requirements, is easy to promote, and realizes the effective extraction and separation of rare earth from rare earth enriched materials. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described below by specific implementation methods. 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.

[0040] Example 1

[0041] This embodiment provides a method for extracting rare earth from rare earth enriched materials, the method comprising the following steps:

[0042] (1) uniformly mixing a precipitate of an ionic mineral leachate having a rare earth content of 50% and a magnesium content of 30% with a propionic acid solution having a propionic acid volume concentration of 20%, and filtering to obtain a leachate and a residue; the mass volume ratio of the precipitate of the ionic mineral leachate to the propionic acid solution is 1 g:6 mL;

[0043] (2) mixing P507 with the leachate obtained in step (1) to obtain a rare earth-containing loaded organic phase and a raffinate; the molar ratio of P507 to the rare earth in the leachate is 7:1; the obtained rare earth-containing loaded organic phase is subjected to countercurrent extraction to obtain a magnesium-loaded organic phase and a rare earth-loaded organic phase; the obtained raffinate is subjected to impurity removal treatment and then reused in step (1);

[0044] (3) The magnesium-loaded organic phase obtained in step (2) is subjected to back extraction treatment with a sulfuric acid solution having a concentration of 6 mol / L to obtain a magnesium sulfate solution and an organic phase; the obtained magnesium sulfate solution is used for mine leaching, and the obtained organic phase is returned to the mixing described in step (2).

[0045] Example 2

[0046] This embodiment provides a method for extracting rare earth from rare earth enriched materials, the method comprising the following steps:

[0047] (1) uniformly mixing a rare earth mineral having a rare earth content of 30% and a magnesium content of 30% and an acetic acid solution having an acetic acid volume concentration of 5%, and filtering to obtain a leachate and a residue; the mass volume ratio of the rare earth mineral to the acetic acid solution is 1 g:2 mL;

[0048] (2) mixing C272 with the leachate obtained in step (1) to obtain a rare earth-containing loaded organic phase and a raffinate; the molar ratio of C272 to the rare earth in the leachate is 3:1; the obtained rare earth-containing loaded organic phase is subjected to countercurrent extraction to obtain a magnesium-loaded organic phase and a rare earth-loaded organic phase; the obtained raffinate is subjected to impurity removal treatment and then reused in step (1);

[0049] (3) The magnesium-loaded organic phase obtained in step (2) is subjected to back extraction treatment with a sulfuric acid solution having a concentration of 7 mol / L to obtain a magnesium sulfate solution and an organic phase; the obtained magnesium sulfate solution is used for mine leaching, and the obtained organic phase is returned to the mixing described in step (2).

[0050] Example 3

[0051] This embodiment provides a method for extracting rare earth from rare earth enriched materials, the method comprising the following steps:

[0052] (1) uniformly mixing a precipitate of a rare earth waste leachate having a rare earth content of 70% and a magnesium content of 10% and a lauric acid solution having a lauric acid volume concentration of 50%, and filtering to obtain a leachate and a residue; the mass volume ratio of the precipitate of the rare earth waste leachate to the lauric acid solution is 1 g:10 mL;

[0053] (2) mixing P507 with the leachate obtained in step (1) to obtain a rare earth-containing loaded organic phase and a raffinate; the molar ratio of P507 to the rare earth in the leachate is 10:1; the obtained rare earth-containing loaded organic phase is subjected to countercurrent extraction to obtain a magnesium-loaded organic phase and a rare earth-loaded organic phase; the obtained raffinate is subjected to impurity removal treatment and then reused in step (1);

[0054] (3) The magnesium-loaded organic phase obtained in step (2) is subjected to back extraction treatment with a sulfuric acid solution having a concentration of 8 mol / L to obtain a magnesium sulfate solution and an organic phase; the obtained magnesium sulfate solution is used for mine leaching, and the obtained organic phase is returned to the mixing described in step (2).

[0055] Example 4

[0056] This embodiment provides a method for extracting rare earths from rare earth enriched materials. The difference from Embodiment 1 is that, except for adjusting the mass volume ratio of the precipitate of the ionic ore leachate to the propionic acid solution in step (1) to 1 g:1 mL, the rest is the same as Embodiment 1.

[0057] Example 5

[0058] This embodiment provides a method for extracting rare earths from rare earth enriched materials. The difference from Embodiment 1 is that, except for adjusting the mass volume ratio of the precipitate of the ionic ore leachate to the propionic acid solution in step (1) to 1 g:12 mL, the rest is the same as Embodiment 1.

[0059] Example 6

[0060] This embodiment provides a method for extracting rare earths from rare earth concentrates. The difference from Embodiment 1 is that, except for adjusting the volume concentration of propionic acid in the propionic acid solution in step (1) to 2%, the rest is the same as Embodiment 1.

[0061] Example 7

[0062] This embodiment provides a method for extracting rare earths from rare earth concentrates. The difference from Embodiment 1 is that, except that the volume concentration of propionic acid in the propionic acid solution in step (1) is adjusted to 55%, the rest is the same as Embodiment 1.

[0063] Example 8

[0064] This embodiment provides a method for extracting rare earth from rare earth concentrates. The difference from Embodiment 1 is that except for adjusting the molar ratio of P507 to the rare earth in the leaching solution in step (2) to 1:1, the rest is the same as Embodiment 1.

[0065] Example 9

[0066] This embodiment provides a method for extracting rare earth from rare earth enriched materials. The difference from Embodiment 1 is that except for adjusting the molar ratio of P507 to the rare earth in the leaching solution in step (2) to 12:1, the rest is the same as Embodiment 1.

[0067] Comparative Example 1

[0068] This comparative example provides a method for extracting rare earths from rare earth concentrates. The difference from Example 1 is that the volume concentration of the propionic acid solution in step (1) is replaced by a hydrochloric acid solution, and the rest is the same as Example 1.

[0069] Comparative Example 2

[0070] This comparative example provides a method for extracting rare earths from rare earth concentrates. The difference from Example 1 is that the raffinate in step (2) is not subjected to impurity removal treatment and is directly reused in step (1). The rest is the same as Example 1.

[0071] Comparative Example 3

[0072] This comparative example provides a method for extracting rare earth from rare earth enriched materials, wherein the method uses sulfuric acid leaching, the leached solution is precipitated with ammonium bicarbonate, the filtrate after precipitation is used to prepare magnesium sulfate for mine leaching, the slag obtained after precipitation is selectively dissolved with hydrochloric acid, and the dissolved rare earth solution is extracted with saponified P507.

[0073] Rare earth was extracted from the rare earth concentrate by the methods provided in Examples 1-9 and Comparative Examples 1-3. The magnesium leaching rate was calculated according to magnesium leaching rate (%) = (magnesium content in raw material (g) - magnesium content in leached residue (g)) / magnesium content in raw material (g) × 100. The rare earth leaching rate was calculated according to rare earth leaching rate (%) = (rare earth content in raw material (g) - rare earth content in leached residue (g)) / rare earth content in raw material (g) × 100. The rare earth extraction rate was calculated according to rare earth extraction rate (%) = rare earth content in organic phase (g) / rare earth content in stock solution (g) × 100. The ammonia nitrogen content in the recycled magnesium salt and the amount of waste salt generated were measured. The results are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] It can be seen from Table 1 that the method for extracting rare earth from rare earth enriched materials provided by the present invention has high leaching rates of magnesium and rare earth, the rare earth extraction rate can reach 100%, there is no ammonia nitrogen in the recycled magnesium salt, and no waste salt is generated in the overall process flow;

[0078] By comparing Example 1 with Examples 4 and 5, it can be seen that the mass volume ratio of the rare earth enrichment to the organic acid solution is too small, and it is difficult to achieve the purpose of completely leaching magnesium and rare earths. The mass volume ratio is too large, resulting in a waste of raw material resources; by comparing Example 1 with Examples 6 and 7, it can be seen that if the organic acid concentration is too low, the leaching rate of rare earth and magnesium will be affected. If the organic acid concentration is too high, the solution in the leachate reaches a saturated concentration, which will also affect the leaching rate; by comparing Example 1 with Examples 8 and 9, it can be seen that if the amount of the acidic phosphorus-type extractant is too low, the rare earth extraction rate will be reduced, and if the amount is too high, the extractant will be wasted and the cost will be increased.

[0079] By comparing Example 1 with Comparative Example 1, it can be seen that the leaching of rare earth and magnesium cannot be achieved by using inorganic acid solution; by comparing Example 1 with Comparative Example 2, it can be seen that the raffinate has no impurity removal step, and a large amount of waste salt will be generated; by comparing Example 1 with Comparative Example 3, it can be seen that organic acid extraction is used without saponification, which reduces the generation of high-salt wastewater from the source, and no ammonia nitrogen is added in the magnesium salt regeneration process, so it is more environmentally friendly to reuse the magnesium salt in the mine.

[0080] In summary, the method for extracting rare earth from rare earth enriched materials provided by the present invention utilizes that rare earth and magnesium hydroxide are easy to be leached from organic acid, and then utilizes the extraction characteristics of rare earth and magnesium in organic acid and acidic phosphorus type extractant, so that extraction can be achieved without saponification, and organic acid can be reused at the same time; utilizing the good separation effect of rare earth and magnesium in organic acid system, the preparation and reuse of magnesium salt can be achieved; the process from leaching to extraction and enrichment of rare earth and separation from impurities does not generate waste salt, waste water, and waste gas, the process flow is short, the operation is simple, the equipment requirements are low, and it is easy to promote, thereby achieving effective extraction and separation of rare earth from rare earth enriched materials.

[0081] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for extracting rare earth from rare earth concentrates, It is characterized in that The method comprises the following steps: (1) uniformly mixing the rare earth enriched material and the organic acid solution, and obtaining a leachate and a residue after solid-liquid separation; (2) mixing an acidic phosphorus-type extractant with the leaching solution obtained in step (1) to obtain a rare earth-containing loaded organic phase and a raffinate; extracting and separating the obtained rare earth-containing loaded organic phase to obtain a magnesium-loaded organic phase and a rare earth-loaded organic phase; and returning the obtained raffinate to step (1) after impurity removal; (3) The magnesium-loaded organic phase obtained in step (2) is subjected to back extraction treatment to obtain a magnesium salt solution and an organic phase; the obtained magnesium salt solution is used for mine leaching, and the obtained organic phase is returned to the mixing described in step (2).

2. The method according to claim 1, It is characterized in that The rare earth concentrate in step (1) includes any one of rare earth minerals, precipitates of ionic ore leaching solution, rare earth waste or precipitates of rare earth waste leaching solution, or a combination of at least two of them.

3. The method according to claim 1 or 2, It is characterized in that The rare earth content of the rare earth enriched material in step (1) is 10-95%, and the magnesium content is 10-40%.

4. The method according to any one of claims 1 to 3, It is characterized in that The organic acid in the organic acid solution of step (1) includes any one of acetic acid, propionic acid or lauric acid, or a combination of at least two thereof; Preferably, the volume concentration of the organic acid in the organic acid solution in step (1) is 5-50%.

5. The method according to any one of claims 1 to 4, It is characterized in that The mass volume ratio of the rare earth enriched material to the organic acid solution in step (1) is 1g:(2-10)mL.

6. The method according to any one of claims 1 to 5, It is characterized in that The acidic phosphorus extractant in step (2) includes any one of P204, P507 or C272, or a combination of at least two of them.

7. The method according to any one of claims 1 to 6, It is characterized in that The molar ratio of the acidic phosphorus-type extractant in step (2) to the rare earth in the leaching solution is (3-10):

1.

8. The method according to any one of claims 1 to 7, It is characterized in that The extraction separation in step (2) includes countercurrent extraction or fractional extraction.

9. The method according to any one of claims 1 to 8, It is characterized in that The stripping treatment in step (3) is carried out using a sulfuric acid solution; Preferably, the concentration of the sulfuric acid solution in step (3) is 6-8 mol / L.

10. The method according to any one of claims 1 to 9, It is characterized in that The magnesium salt solution in step (3) includes magnesium sulfate solution.

Images