A method for leaching ionic phase rare earth in ionic rare earth ore and its application

Abstract

The present invention provides a method for leaching ionic phase rare earth in ionic rare earth ore and its application, the method comprising the following steps: 1) compounding a first organic acid, a second organic acid, and a third organic acid by a compatibility technology and mixing them with a solvent to obtain a leaching agent solution; 2) mixing the leaching agent solution with the ionic rare earth ore, reacting, and obtaining a leachate containing rare earth elements; wherein the first organic acid, the second organic acid, and the third organic acid independently include any one of acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid, or ascorbic acid or a combination of at least two. The present invention greatly inhibits the re-adsorption of rare earth ions on clay minerals by compounding the first organic acid, the second organic acid, and the third organic acid, and combines ion exchange reaction and multi-system enhanced complexation, thereby reducing the amount of leaching agent and effectively improving the efficiency of ionic phase rare earth leaching. In addition, the leaching agent remaining in the mine can be quickly transformed by microorganisms, accelerating the ecological restoration of the mine, and realizing the eco-friendly leaching of ionic rare earth resources.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth mineral extraction, and in particular relates to a method for leaching ionic phase rare earth in ionic rare earth ore and application thereof. Background Art

[0002] Rare earth elements have unique optical, electrical, and magnetic properties and are indispensable elements for infrastructure, technology, and modern life. In recent years, the global market demand for rare earths, especially heavy rare earths, has grown dramatically. Rare earth elements are abundant in the world, but most of them are light rare earth elements, while medium and heavy rare earth elements with high value and low substitutability have small reserves and large gaps. Ion-adsorbed rare earth ores refer to rare earths that are adsorbed by adsorbents in ionic form and can be leached by ion exchange. The adsorbents mentioned here are mainly clay minerals and colloidal particles that are widely present in nature. Their surfaces are negatively charged and have adsorption capacity for cations, especially for high-valent ions. The uniqueness of ionic rare earth ores is that rare earth elements are mainly adsorbed on minerals such as clay and mica in the weathering crust in an ionic state. They have the characteristics of complete rare earth distribution, low radioactivity, easy mining, and rich in medium and heavy rare earth elements.

[0003] At present, ionic rare earths are mainly mined through in-situ leaching processes. For example, CN114703365A discloses a composite leaching agent for weathering crust leaching rare earth ores. This method forms a composite leaching solution by adding humic acid to the traditional ammonium sulfate leaching agent, and injects it into the ore body to leach the ionic rare earth ores. This method uses ammonium sulfate as a leaching agent, which causes serious ecological damage and ammonia nitrogen pollution to the mine soil and surrounding water bodies, acidifies the soil in the mining area, and causes imbalance of plant nutrients such as N, P, and K, affecting the natural ecological recovery process of the mining area. Excessive ammonia nitrogen will also cause excessive ammonia nitrogen in the soil and groundwater around the mine.

[0004] In order to reduce ammonia and nitrogen pollution during rare earth mining, ammonia-free leaching agents such as magnesium sulfate are used in in-situ leaching processes. For example, CN108034842A discloses a green and environmentally friendly ammonium-free mining process for ionic rare earth ores, and the steps are as follows: a certain concentration of ammonium-free leaching agent is injected from the injection holes arranged in the mining area, and an ion exchange reaction occurs with the rare earth mineral to obtain a mother liquor enriched in rare earth cations; the mother liquor seeps and converges to the natural waterproof bottom plate of the ore layer or the artificial liquid collection tunnel with liquid collection diversion holes and other liquid collection projects; it is then transported to the hydrometallurgical workshop through the main transportation pipeline, and ammonium-free agents are used for impurity removal and precipitation to obtain rare earth carbonates. The supernatant is circulated back to the liquid preparation tank, and after adjusting the pH value and adding agents, it is returned to the mining area as a new ammonium-free leaching agent. CN111636003A discloses a leaching method for southern ionic rare earth ores, which follows the existing engineering system of in-situ leaching, including injection wells, liquid collection tunnels, diversion holes, liquid collection trenches, etc., uses a neutral leaching agent magnesium sulfate as a leaching solution, adopts a method of slow leaching with small amounts of water and elution with large amounts of water, uses cationic magnesium to exchange rare earth ions and hydrogen ions adsorbed by clay, produces a mobile acidic solution system, and then uses large amounts of water elution to allow rare earth ions in the ore body to migrate out of the ore body with the magnesium sulfate electrolyte solution and be recovered. However, this ammonia-free leaching agent brings about the accumulation of magnesium ions in the soil while avoiding ammonia nitrogen pollution, which seriously damages the ecological stability of the mine soil.

[0005] In addition, during the in-situ leaching process, the rare earth ions exchanged by the leaching agent will be re-adsorbed in the clay minerals, thereby reducing the mining rate of rare earths. Therefore, in order to achieve a high mining rate of ionic rare earths, it is necessary to use a leaching agent that far exceeds the theoretical amount, otherwise a large amount of ionic rare earths will remain. Therefore, there is a serious waste of resources in the rare earth mining process using existing leaching agents.

[0006] Therefore, developing an eco-friendly, pollution-free, low-cost and efficient leaching technology is a difficult problem that needs to be solved urgently. Summary of the invention

[0007] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method for leaching ionic rare earths in ionic rare earth ores and its application. The present invention uses a multi-component leaching system composed of multiple organic acids as an organic acid leaching agent, and through an ion exchange reaction, a strong complexation of rare earth cations and organic acid radicals is achieved, which greatly inhibits the re-adsorption of rare earth ions on clay minerals and achieves a high efficiency of rare earth ion leaching. In addition, the organic acid leaching agent remaining in the mine soil can be quickly transformed by microorganisms, reducing the ecological recovery time of ionic rare earth mines, and achieving low-cost, efficient, and eco-friendly leaching of ionic rare earth resources.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0010] (1) mixing a first organic acid, a second organic acid and a solvent to obtain a leaching agent solution;

[0011] (2) mixing the leaching agent solution and the ionic rare earth ore to react and obtain a leaching solution containing rare earth elements;

[0012] Wherein, the first organic acid and the second organic acid independently include any one of acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid, or ascorbic acid, or a combination of at least two thereof.

[0013] The mining of ionic rare earth ores is essentially an ion exchange reaction between the cations of the leaching agent and the hydrated rare earth ions or hydroxyl hydrated rare earth ions adsorbed on the clay minerals. The leaching ability of the leaching agent is related to the charge density of the cations in the leaching agent, that is, the cations with high charge density have stronger exchange ability for rare earth ions. + It has a very high charge density and a strong ion exchange capacity with the rare earth ions attached to clay minerals. Through proton exchange, rare earth elements can be leached from minerals. In addition, organic acids can form ligand complexes with metal elements, thereby reducing the saturation of metal elements in the solution and promoting the forward leaching of rare earths. Therefore, organic acids have stronger exchange and complexing abilities for ionic rare earths, which can reduce the amount of leaching agents used while achieving a higher rare earth leaching rate and reducing the waste of rare earth resources. However, the ion exchange process is a reversible process, that is, it is leached by H + The rare earth cations displaced from clay minerals will be adsorbed back onto clay minerals. Due to the limitation of the complexation of the binary system, the combination of a single organic acid anion and a rare earth cation still has a certain amount of rare earth cations adsorbed back onto clay minerals, resulting in incomplete leaching of rare earths.

[0014] The present invention uses a multi-component leaching system composed of a first organic acid and a second organic acid as an organic acid leaching agent, and through an ion exchange reaction, realizes a strong complexation of rare earth cations and organic acid radicals, greatly inhibits the re-adsorption of rare earth ions on clay minerals, and realizes a high efficiency of rare earth ion leaching. In addition, the organic acid leaching agent remaining in the mine soil can be quickly transformed by microorganisms, reducing the ecological recovery time of ionic rare earth mines, and realizing low-cost, efficient, and eco-friendly leaching of ionic rare earth resources.

[0015] It should be noted that, in the present invention, "independently" means that the first organic acid can be selected from any one of acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid, or ascorbic acid, or a combination of at least two thereof, and the second organic acid can be selected from any one of acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid, or ascorbic acid, or a combination of at least two thereof, and the two organic acids do not interfere with each other when selecting their types, and can select the same type or different types.

[0016] Preferably, the molar ratio of the first organic acid to the second organic acid is (0.5-1.5):(0.5-1.5), wherein the selection range of the first organic acid 0.5-1.5 can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5, etc., and the selection range of the second organic acid 0.5-1.5 can be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5, etc.

[0017] In the present invention, if the molar ratio of the first organic acid to the second organic acid is too small, that is, the amount of the first organic acid is too little, the leaching rate of the ionic phase rare earth is reduced, thereby reducing the complexing ability of the leaching agent in the multi-competitive complexing system, and part of the leached rare earth ions are adsorbed back on the clay mineral, resulting in a decrease in the overall rare earth leaching rate; if the molar ratio of the first organic acid to the second organic acid is too large, that is, the amount of the first organic acid is too much, the leaching cost of the leaching agent is increased, and at the same time, the difficulty of separating and purifying the rare earth ions in the later leaching mother liquor is increased, and the total production cost of the rare earth is simultaneously increased.

[0018] Preferably, the organic acid leaching agent further comprises a third organic acid, and the third organic acid comprises any one of acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid or ascorbic acid, or a combination of at least two thereof.

[0019] Preferably, the molar ratio of the first organic acid, the second organic acid and the third organic acid is (1-3):1:(0.1-1), wherein the selection range of the first organic acid 1-3 can be, for example, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8 or 3, and the selection range of the third organic acid 0.1-1 is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.

[0020] In the present invention, if the molar ratio of the first organic acid to the third organic acid is too small, that is, the dosage of the third organic acid is too large, while the rare earth leaching rate is increased, the difficulty of separation and purification is further increased, resulting in an increase in the overall production cost; if the molar ratio of the first organic acid to the third organic acid is too large, that is, the dosage of the third organic acid is too small, rare earth ions that are difficult to be dissociated will remain on the clay mineral, that is, the leaching of the rare earth ions is not complete, or the dosage of the leaching agent will increase.

[0021] Preferably, the concentration of the leaching agent solution in step (1) is 0.02-2 mol / L, for example, it can be 0.02 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L or 2 mol / L, etc. It should be noted that the concentration of the leaching agent solution refers to the molar concentration of the combination of multiple organic acids in the solution, preferably 0.05-1 mol / L.

[0022] Preferably, the solvent in step (1) comprises water.

[0023] Preferably, after the mixing in step (1), the pH value of the mixed solution is adjusted.

[0024] In one embodiment, the reagent used to adjust the pH value of the mixed solution is an acid or a base, the acid may be, for example, sulfuric acid, and the base may be, for example, sodium hydroxide.

[0025] Preferably, the pH value is 1-5, for example, 1, 2, 3, 4 or 5.

[0026] Preferably, in step (2), the solid-to-liquid ratio of the ionic rare earth ore to the leaching agent solution is 1:(1-12), for example, it can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11 or 1:12, etc. It should be noted that the solid-to-liquid ratio refers to the mass ratio of the ionic rare earth ore to the leaching agent solution.

[0027] Preferably, the reaction time of step (2) is 4-12 h, for example, it can be 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h.

[0028] Preferably, the mixing method in step (2) includes any one of pond leaching, heap leaching, column leaching or in-situ leaching, preferably column leaching.

[0029] Preferably, the specific steps of the column leaching method include:

[0030] The ionic rare earth ore is placed in a leaching column, and then the leaching agent solution is added.

[0031] Preferably, in the column leaching method, the addition rate of the leaching agent solution is 0.1-5 mL / min, for example, it can be 0.1 mL / min, 0.3 mL / min, 0.6 mL / min, 0.9 mL / min, 1.2 mL / min, 1.5 mL / min, 1.8 mL / min, 2.1 mL / min, 2.4 mL / min, 2.7 mL / min, 3 mL / min, 4 mL / min or 5 mL / min.

[0032] Preferably, the rare earth grade of the ionic rare earth ore in step (2) is 0.05-0.8%, for example, it can be 0.05%, 0.1%, 0.2%, 03%, 04%, 0.5%, 0.6%, 0.7% or 0.8%, etc.

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

[0034] (1) mixing a first organic acid, a second organic acid and water, and adjusting the pH value of the mixed solution to 1-5 to obtain a leaching agent solution with a concentration of 0.02-2 mol / L;

[0035] (2) placing the ionic rare earth ore in a leaching column, adding a leaching agent solution according to a solid-liquid ratio of 1:(1-12), reacting for 4-12 hours, and obtaining the leaching solution containing the rare earth elements;

[0036] Wherein, the first organic acid and the second organic acid independently include any one of acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid, or ascorbic acid, or a combination of at least two thereof.

[0037] In a second aspect, the present invention provides an application of the method described in the first aspect, wherein the method is applied to extract ionic phase rare earths from ionic rare earth ores.

[0038] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention uses a multi-component leaching system composed of a first organic acid and a second organic acid as an organic acid leaching agent, and achieves a strong complexation between rare earth cations and organic acid radicals through an ion exchange reaction, greatly inhibits the re-adsorption of rare earth ions on clay minerals, and achieves a high efficiency of leaching rare earth ions;

[0041] (2) The method provided by the present invention reduces the amount of leaching agent used while achieving efficient leaching of ionic rare earths. At the same time, the organic acid leaching agent remaining in the mine soil can be quickly converted by microorganisms, reducing the ecological recovery time of the ionic rare earth mine and achieving low-cost, efficient and eco-friendly leaching of ionic rare earth resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 XRD patterns of the ionic rare earth ores used in Examples 1-19 and Comparative Examples 1-3 of the present invention.

[0043] Figure 2 This is a PCA analysis diagram of different elements leached by organic acid provided by the present invention.

[0044] Figure 3 The figure is a comparison chart of the leaching rate of ionic phase rare earth elements in the leachate prepared in Example 1 of the present invention and Comparative Examples 1-3. DETAILED DESCRIPTION

[0045] 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.

[0046] In the embodiments provided by the present invention, the ionic rare earth ores used are the same, mainly containing substances such as feldspar, quartz, kaolin, etc., in which the silicon and aluminum content accounts for the vast majority. In addition, the chemical composition of the ionic rare earth ores and the data of the all-phase rare earth distribution are detailed in Tables 1 and 2. Among them, the all-phase refers to the percentage of the content of each rare earth oxide in the ionic rare earth ores to the total amount of rare earth oxides.

[0047] Table 1

[0048]

[0049]

[0050] Table 2

[0051]

[0052] The specific implementation method is as follows

[0053] Example 1

[0054] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0055] (1) mixing a first organic acid, a second organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 2, thereby obtaining a leaching agent solution with a concentration of 0.1 mol / L;

[0056] Wherein, the first organic acid is acetic acid, the second organic acid is malic acid, and the molar ratio of acetic acid to malic acid is 1:1.

[0057] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.107% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:3, and the ore sample was column leached at a liquid addition rate of 1.25 mL / min. After reacting for 8 hours, the leaching solution containing rare earth elements was obtained.

[0058] Example 2

[0059] The difference between this embodiment and embodiment 1 is that the pH value of the mixed solution is adjusted to 1 in step (1).

[0060] The rest of the preparation methods and parameters were the same as those in Example 1.

[0061] Example 3

[0062] The difference between this embodiment and embodiment 1 is that the pH value of the mixed solution adjusted in step (1) is 1.5.

[0063] The rest of the preparation methods and parameters were the same as those in Example 1.

[0064] Example 4

[0065] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0066] (1) mixing a first organic acid, a second organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 3, thereby obtaining a leaching agent solution with a concentration of 0.5 mol / L;

[0067] Wherein, the first organic acid is acetic acid, the second organic acid is citric acid, and the molar ratio of acetic acid to citric acid is 1:1.

[0068] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.107% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:3, and the ore sample was column leached at a liquid addition rate of 1.68 mL / min. After reacting for 6 hours, the leaching solution containing rare earth elements was obtained.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 4 is that the pH value of the mixed solution is adjusted to 4 in step (1).

[0071] The rest of the preparation methods and parameters were the same as those in Example 1.

[0072] Example 6

[0073] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0074] (1) mixing a first organic acid, a second organic acid, a third organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 2, thereby obtaining a leaching agent solution with a concentration of 1 mol / L;

[0075] Wherein, the first organic acid is isobutyric acid, the second organic acid is citric acid, the third organic acid is ascorbic acid, and the molar ratio of isobutyric acid, citric acid and ascorbic acid is 3:1:0.1.

[0076] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.107% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:3, and the ore sample was column leached at a liquid addition rate of 1.0 mL / min. After reacting for 10 hours, the leaching solution containing rare earth elements was obtained.

[0077] Example 7

[0078] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0079] (1) mixing a first organic acid, a second organic acid, a third organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 2, thereby obtaining a leaching agent solution with a concentration of 2 mol / L;

[0080] Wherein, the first organic acid is isobutyric acid, the second organic acid is citric acid, and the third organic acid is ascorbic acid including isobutyric acid, citric acid and ascorbic acid, and the molar ratio of isobutyric acid, citric acid and ascorbic acid is 1:1:1.

[0081] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.107% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:3, and the ore sample was column-leached at a liquid addition rate of 2.5 mL / min. After reacting for 4 hours, the leaching solution containing rare earth elements was obtained.

[0082] Example 8

[0083] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0084] (1) mixing a first organic acid, a second organic acid, a third organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 2, thereby obtaining a leaching agent solution with a concentration of 0.05 mol / L;

[0085] Wherein, the first organic acid is isobutyric acid, the second organic acid is malic acid, the third organic acid is tartaric acid, and the molar ratio of isobutyric acid, malic acid and tartaric acid is 2:1:0.5.

[0086] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.107% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:7, and the ore sample was column-leached at a liquid addition rate of 2.0 mL / min. After reacting for 12 hours, the leaching solution containing rare earth elements was obtained.

[0087] Example 9

[0088] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0089] (1) mixing a first organic acid, a second organic acid, a third organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 2, thereby obtaining a leaching agent solution with a concentration of 0.05 mol / L;

[0090] Wherein, the first organic acid is isobutyric acid, the second organic acid is malic acid, the third organic acid is citric acid, and the molar ratio of isobutyric acid, malic acid and citric acid is 1:1:0.5.

[0091] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.074% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:8, and the ore sample was column-leached at a liquid addition rate of 3.3 mL / min. After reacting for 8 hours, the leaching solution containing rare earth elements was obtained.

[0092] Example 10

[0093] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0094] (1) mixing a first organic acid, a second organic acid and water, and using a sodium hydroxide solution as a pH adjuster to adjust the pH value of the mixed solution to 3, thereby obtaining a leaching agent solution with a concentration of 0.02 mol / L;

[0095] Wherein, the first organic acid is isobutyric acid, the second organic acid is malic acid, and the molar ratio of isobutyric acid to malic acid is 0.5:1.5.

[0096] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.15% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:12, and the ore sample was column-leached at a liquid addition rate of 2.8 mL / min. After reacting for 12 hours, the leaching solution containing rare earth elements was obtained.

[0097] Embodiment 11

[0098] This embodiment provides a method for leaching ionic rare earth in ionic rare earth ore, the method comprising the following steps:

[0099] (1) mixing a first organic acid, a second organic acid and water, and using sulfuric acid as a pH adjuster to adjust the pH value of the mixed solution to 2, thereby obtaining a leaching agent solution with a concentration of 0.2 mol / L;

[0100] Wherein, the first organic acid is isobutyric acid, the second organic acid is citric acid, and the molar ratio of isobutyric acid to citric acid is 1.5:0.5.

[0101] (2) 200 g of dried ionic rare earth ore with a rare earth grade of 0.05% was taken, and the ore sample was loaded into a leaching column with an inner diameter of 4 cm. A leaching agent solution was added according to a solid-liquid ratio of 1:1, and the ore sample was column-leached at a liquid addition rate of 0.3 mL / min. After reacting for 10 hours, the leaching solution containing rare earth elements was obtained.

[0102] Example 12

[0103] The difference between this embodiment and embodiment 1 is that the molar ratio of acetic acid to malic acid in step (1) is 0.5:1.

[0104] The rest of the preparation methods and parameters were the same as those in Example 1.

[0105] Example 13

[0106] The difference between this embodiment and embodiment 1 is that the molar ratio of acetic acid to malic acid in step (1) is 1:0.5.

[0107] The rest of the preparation methods and parameters were the same as those in Example 1.

[0108] Embodiment 14

[0109] The difference between this embodiment and embodiment 1 is that the second organic acid is acetic acid.

[0110] The rest of the preparation methods and parameters were the same as those in Example 1.

[0111] Embodiment 15

[0112] The difference between this embodiment and embodiment 6 is that the second organic acid is isobutyric acid, and the third organic acid is isobutyric acid. The rest of the preparation methods and parameters are the same as those in embodiment 6.

[0113] Example 16

[0114] The difference between this embodiment and embodiment 9 is that the molar ratio of isobutyric acid, malic acid and citric acid is 0.5:1:1.

[0115] The rest of the preparation methods and parameters were the same as those in Example 9.

[0116] Embodiment 17

[0117] The difference between this embodiment and embodiment 9 is that the molar ratio of isobutyric acid, malic acid and citric acid is 2.5:1:0.5.

[0118] The rest of the preparation methods and parameters were the same as those in Example 9.

[0119] Comparative Example 1

[0120] The difference between this comparative example and Example 1 is that the leaching agent solution in step (1) contains only the first organic acid, that is, does not contain the second organic acid.

[0121] The rest of the preparation methods and parameters were the same as those in Example 1.

[0122] Comparative Example 2

[0123] The difference between this comparative example and Example 1 is that in step (1), the first organic acid and the second organic acid are replaced by magnesium sulfate.

[0124] The rest of the preparation methods and parameters were the same as those in Example 1.

[0125] Comparative Example 3

[0126] The difference between this comparative example and Example 1 is that in step (1), the first organic acid and the second organic acid are replaced by ammonium sulfate.

[0127] The rest of the preparation methods and parameters were the same as those in Example 1.

[0128] Figure 1 The XRD patterns of the ionic rare earth ores used in Examples 1-17 and Comparative Examples 1-3 are shown. It can be seen from the figure that the raw rare earth ores used mainly contain orthoclase KAlSi3O8, calcium feldspar CaAl2SiO8 and other substances, and the PDF cards corresponding to the patterns all contain feldspar, quartz, kaolin (the XRD diffraction peaks of clay minerals overlap), etc. The raw ore belongs to the ionic rare earth ore of biotite granite, which is mainly composed of fully weathered layer minerals, and the matrix is ​​mostly composed of fine biotite and dispersed sand.

[0129] Figure 2 The PCA analysis diagram of different elements leached by organic acids and magnesium sulfate is shown, where YDS represents isobutyric acid, PGS represents malic acid, NMS represents citric acid, JSS represents tartaric acid, YS represents acetic acid, and KHXS represents ascorbic acid.

[0130] Performance Testing

[0131] The leaching solutions containing rare earth elements prepared in Examples 1-17 and Comparative Examples 1-3 were tested for leaching rate, and the test process was as follows:

[0132] For the rare earth leaching solution containing rare earth elements, the residual organic acid is digested with nitric acid and perchloric acid, and then tested by inductively coupled plasma emission spectrometer, and the ionic phase rare earth leaching rate is calculated. The calculation formula is as follows:

[0133]

[0134] Where: η is the ion phase rare earth leaching rate; m1 is the total rare earth content in the leachate; m2 is the ion phase rare earth content in the original ore;

[0135] Among them, the calculation formula for the total rare earth content in the leaching solution is:

[0136]

[0137] Where: m1 is the total rare earth content in the leachate; c1 is the total rare earth ion concentration tested by ICP-OES; V is the total volume of the dilution solution for the dilution test; n is the dilution multiple; and m is the total mass of the original ore.

[0138] The test method for ionic phase rare earth content refers to the determination of the total amount of ionic phase rare earth in the chemical analysis method of ionic rare earth ore in XB / T 619-2015.

[0139] Test conditions: The test instrument is Jena PQ9000 inductively coupled plasma optical emission spectrometer (ICP-OES), and the spectral lines of rare earth elements are selected as shown in Table 3.

[0140] Table 3

[0141]

[0142] The above test method was used to test the leachate prepared in Example 1 and Comparative Examples 1-3. Figure 3 As shown in the figure, it can be seen that the rare earth leaching rate obtained by the method provided by the present invention is significantly better than that of comparative examples 1-3.

[0143] The test results of Examples 1-19 and Comparative Examples 1-3 are summarized in Table 4.

[0144] Table 4

[0145] Ionic phase rare earth leaching rate / % Example 1 96.36±0.72 Example 2 100±0 Example 3 99.85±0.15 Example 4 89.87±2.20 Example 5 81.52±3.51 Example 6 98.89±0.32 Example 7 88.31±1.33 Example 8 96.73±0.35 Example 9 99.35±0.13 Example 10 98.95±0.15 Embodiment 11 93.55±0.96 Example 12 88.93±1.92 Example 13 85.13±2.31 Embodiment 14 90.36±1.95 Embodiment 15 87.17±2.10 Example 16 93.81±0.52 Embodiment 17 95.60±0.36 Comparative Example 1 83.52±0.45 Comparative Example 2 72.29±2.01 Comparative Example 3 73.31±2.03

[0146] analyze:

[0147] As can be seen from the above table, the present invention uses a multi-component leaching system of a plurality of organic acids as an organic acid leaching agent, and achieves a strong complexation of rare earth cations and organic acid radicals through ion exchange reaction, which greatly inhibits the re-adsorption of rare earth ions on clay minerals and achieves a high efficiency of leaching of rare earth ions.

[0148] Example 5 Compared with Examples 1-4 and Examples 6-11, the H in the leaching agent solution for replacing rare earth cations + The concentration is low, so the ion exchange capacity decreases, which reduces the leaching efficiency of rare earth ions.

[0149] By comparing the data results of Example 1 with those of Examples 12-13, it can be seen that if the molar ratio of acetic acid to malic acid is too small, excessive malic acid usage will result in increased leaching costs during the leaching process; if the molar ratio of acetic acid to malic acid is too large, part of the rare earth cations exchanged by acetic acid will be adsorbed back onto clay minerals and solidified organic matter in clay minerals, and the number of rare earth cations enhanced by malic acid complexing will decrease, ultimately leading to a decrease in the rare earth leaching rate.

[0150] By comparing the data results of Example 1 with Example 14, and Example 6 with Example 15, it can be seen that when the same leaching parameters and the same leaching agent concentration are used, the leaching rate of the composite organic acid leaching agent is better than that of the single organic acid leaching agent. This is mainly because when the same type of organic acid is used for leaching, the complexing ability of the organic acid leaching system for rare earth ions is inferior to that of the multi-component complexing system of the composite organic acid.

[0151] From the comparison of the data results of Example 1 and Comparative Example 1, it can be seen that the multi-organic acid leaching system has a significantly better leaching effect on ionic phase rare earth than the single organic acid leaching system. Using a single organic acid will reduce the leaching rate of ionic phase rare earth.

[0152] From the comparison of the data results of Example 1 and Comparative Examples 2-3, it can be seen that the leaching effect of the organic acid leaching system on ionic phase rare earth is significantly better than that of the chemical leaching agents magnesium sulfate and ammonium sulfate.

[0153] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by 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 leaching ionic rare earths from ionic rare earth ores, characterized in that: The method comprises the following steps: (1) mixing the first organic acid, the second organic acid, and the third organic acid with a solvent to obtain a leaching agent solution; (2) mixing the leaching agent solution and the ionic rare earth ore to react and obtain a leaching solution containing rare earth elements; Wherein, the molar ratio of the first organic acid, the second organic acid and the third organic acid is (1-3):1:(0.1-1); The leaching agent enables the rare earth cations to be strongly complexed with organic acid radicals, thereby inhibiting the re-adsorption of the rare earth ions on the clay minerals; The first organic acid, the second organic acid and the third organic acid are independently selected from acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid or ascorbic acid.

2. The method according to claim 1, characterized in that The concentration of the leaching agent solution in step (1) is 0.02-2 mol / L.

3. The method according to claim 2, characterized in that The concentration of the leaching agent solution in step (1) is 0.05-1 mol / L.

4. The method according to claim 1, characterized in that: The solvent in step (1) includes water.

5. The method according to claim 1, characterized in that After the mixing in step (1), the pH value of the mixed solution is adjusted.

6. The method according to claim 5, characterized in that The pH value is 1-5.

7. The method according to claim 1, characterized in that In step (2), the solid-to-liquid ratio of the ionic rare earth ore to the leaching agent solution is 1:(1-12).

8. The method according to claim 1, characterized in that The reaction time of step (2) is 4-12 hours.

9. The method according to claim 1, characterized in that: The mixing method in step (2) includes any one of pond leaching, heap leaching, column leaching or in-situ leaching.

10. The method according to claim 9, characterized in that The mixing method in step (2) is column leaching.

11. The method according to claim 10, characterized in that The specific steps of the column leaching method include: The ionic rare earth ore is placed in a leaching column, and then the leaching agent solution is added.

12. The method according to claim 11, characterized in that In the column leaching method, the addition rate of the leaching agent solution is 0.1-5 mL / min.

13. The method according to claim 1, characterized in that The method comprises the following steps: (1) mixing the first organic acid, the second organic acid and the third organic acid with water, adjusting the pH value of the mixed solution to 1-5, and obtaining a leaching agent solution with a concentration of 0.02-2 mol / L; (2) placing the ionic rare earth ore in a leaching column, adding a leaching agent solution according to a solid-liquid ratio of 1:(1-12), reacting for 4-12 hours, and obtaining the leaching solution containing the rare earth elements; wherein the first organic acid, the second organic acid and the third organic acid are independently selected from acetic acid, isobutyric acid, malic acid, citric acid, tartaric acid or ascorbic acid; The molar ratio of the first organic acid, the second organic acid and the third organic acid is (1-3):1:(0.1-1).

14. An application of the method according to any one of claims 1 to 13, characterized in that: The method is applied to extracting ionic phase rare earths from ionic rare earth ores.

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