A step-by-step extraction method of ion-type rare earth ore and rare earth solution

Abstract

The application provides a step-by-step extraction method of ionic rare earth ore and a rare earth solution, and the step-by-step extraction method comprises the following steps: (1) leaching the ionic rare earth ore with a first leaching agent to obtain a leaching solution and a leaching residue; (2) leaching the leaching residue obtained in the step (1) with a second leaching agent to obtain a leaching solution and a leaching residue; (3) leaching the leaching residue obtained in the step (2) with a third leaching agent to obtain a leaching solution and a leaching residue; (4) leaching the leaching residue obtained in the step (3) with a fourth leaching agent to obtain a leaching solution and a leaching residue; (5) leaching the leaching residue obtained in the step (4) with a fifth leaching agent to obtain a leaching solution and a leaching residue; and (6) performing acid leaching on the leaching residue obtained in the step (5) after sintering to obtain a leaching solution and a leaching residue. The step-by-step extraction method can selectively leach the ionic rare earth ore with different weathering degrees, and the extraction rate of the rare earth in the ionic rare earth ore is relatively high.

Description

Technical Field

[0001] This invention belongs to the field of rare earth extraction technology, and relates to a stepwise extraction method for ionic rare earth minerals, and more particularly to a stepwise extraction method for ionic rare earth minerals and a rare earth solution. Background Technology

[0002] Rare earth elements possess unique atomic structures, resulting in excellent optical, electrical, magnetic, and thermal properties. Often referred to as "industrial MSG," they are widely used in aerospace, energy, transportation, medical, and agricultural fields. Rare earth elements can be divided into light rare earths and heavy rare earths. Heavy rare earths are indispensable key elements in cutting-edge fields such as new materials and deep space exploration. Ion-adsorption rare earth ores are currently a major source of heavy rare earth resources, supplying approximately 20% of the world's rare earth elements and over 90% of heavy rare earth products. Therefore, rare earth elements, especially heavy rare earths, have an increasingly significant impact on current technological development.

[0003] Ion-adsorption rare earth minerals are formed when granite undergoes long-term weathering, disrupting its rock structure. Rare earth elements (REEs) migrate and accumulate in a specific layer of the weathering crust under the influence of internal and external fluids. Due to variations in the degree of weathering, the REE content varies significantly across different weathering crust layers. Typically, the parent rock of the granite weathering crust is largely unweathered or only minimally weathered, and its REEs exist primarily in mineral form, mainly as independent REE minerals such as bastnaesite and monazite, and REE-bearing minerals such as sphene, apatite, and zircon. Different degrees of weathering occur in the weathering layers of the crust, resulting in various weathering morphologies. Weakly weathered crusts retain some parent rock characteristics, but their mineral bonding and composition have undergone significant changes. Under weathering, minerals gradually break down, some disappear, and some transform into other minerals. The REEs in these minerals are released and, under various influences, are present in the weathering crust. Some are adsorbed by weathered clay minerals, while others combine with other substances to form complex states. The parent rock characteristics of highly weathered crusts are basically lost. The mineral assemblage is mainly composed of minerals that are difficult to weather and clay minerals formed by the weathering of other minerals. In some samples, clay minerals can account for more than 20% of the total mineral content. The clay minerals in this area are mainly kaolinite, halloysite, and illite. The high specific surface area and cation exchange capacity of these minerals promote the adsorption of rare earth elements by clay. Therefore, rare earth elements are often enriched in highly weathered crust areas.

[0004] CN112410554A discloses a green extraction method for calcium salts from ionic rare earth ores. This method uses calcium salts, the main component of the ore, as the leaching agent, and adds a small amount of a composite salt leaching agent composed of aluminum, iron, and ammonium ions. The pH value of the leaching process is adjusted by the hydrolysis of the strong acid-weak base salt of aluminum, iron, and ammonium ions, thereby promoting the leaching of rare earth elements and achieving efficient and green extraction of ionic rare earths. However, this green extraction method for calcium salts from ionic rare earth ores has a relatively low rare earth extraction rate.

[0005] CN112176209A discloses a green extraction method for calcium salt systems of ionic rare earth ores. This method uses calcium salt as the leaching agent, calcium oxide as the purification agent, and calcium oxide as the precipitant. The leaching agent is recovered in the form of a composite salt, and chlorine and heavy metals are removed. The entire process produces no ammonia nitrogen or high-salt wastewater discharge, has a smooth flow, and produces products with low impurity content. The environmental impact on the mining area is minimal after mine closure, enabling green and environmentally friendly mining of ionic rare earths. However, this green extraction method for calcium salt systems of ionic rare earth ores has a low rare earth extraction rate and cannot extract rare earths from ionic rare earth ores with different weathering degrees.

[0006] Currently available extraction methods for ion-adsorption rare earth ores all have certain drawbacks, including the inability to extract rare earths from ion-adsorption rare earth ores with varying degrees of weathering and low extraction rates. Therefore, developing a novel extraction method for ion-adsorption rare earth ores is of paramount importance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a stepwise extraction method and rare earth solution for ionic rare earth ores. The stepwise extraction method for ionic rare earth ores provided by the present invention involves leaching using five different leaching processes, followed by acid leaching of the final leaching residue after sintering, resulting in six leaching solutions and residues. This stepwise extraction method can selectively leach ionic rare earth ores with different weathering degrees, achieving a high extraction rate of rare earth elements from ionic rare earth ores. Interference between leaching agents in each step is minimal, enabling efficient leaching of rare earth elements in different occurrence states, maximizing resource utilization, and possessing high economic value.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0010] (1) Ion-type rare earth ore is leached with the first leaching agent to obtain leaching solution and leaching residue;

[0011] (2) The leaching residue obtained in step (1) is leached with the second leaching agent to obtain leaching solution and leaching residue;

[0012] (3) The leaching residue obtained in step (2) is leached with a third leaching agent to obtain leaching solution and leaching residue;

[0013] (4) The leaching residue obtained in step (3) is leached with the fourth leaching agent to obtain leaching solution and leaching residue;

[0014] (5) The leaching residue obtained in step (4) is leached with the fifth leaching agent to obtain leaching solution and leaching residue;

[0015] (6) The leaching residue obtained in step (5) is sintered and then acid-leached to obtain leaching solution and leaching residue.

[0016] In this invention, rare earth elements (REEs) in ion-adsorption rare earth ores exist in various forms. The occurrence state of REEs in the weathering crust reflects the geochemical behavior of REEs during migration, enrichment, and differentiation. Based on the differences in solubility and dissolution rate of various minerals or compounds in different chemical solvents, the occurrence of REEs can be classified into six states by selectively dissolving and leaching the content of various mineral or compound forms of REEs in ion-adsorption rare earth ores: water-soluble state (existing in a hydrated free state), exchangeable adsorbed state (adsorbed on the surface of clay minerals in the form of easily leached 8-9 coordination hydrated complexes), carbonate-bound state (existing in a form bound to carbonates), organic-bound state (existing in a form complexed with humic acid and organic matter), iron-manganese oxide state (existing in a form bound to iron-manganese oxides through adsorption or co-precipitation), and residual state (existing in a form remaining in rare earth minerals and rare earth-containing minerals and not selectively dissolved by chemical reagents). In the weathering crust, the exchangeable adsorbed state, also known as the ion-exchangeable state, is the rare earth element that can currently be mined and extracted. It accounts for more than 50% of the total rare earth element. It is usually extracted using ammonium salt or magnesium salt leaching agents. However, the exchangeable adsorbed rare earth elements are mostly distributed in the highly weathered areas of the weathering crust, and are less distributed in other areas.

[0017] The stepwise extraction method for ion-adsorption rare earth ores provided by this invention involves leaching using five different methods, followed by acid leaching of the final leaching residue after sintering, resulting in six leaching solutions and residues. This stepwise extraction method can selectively leach ion-adsorption rare earth ores with different weathering degrees, achieving a high extraction rate of rare earth elements from ion-adsorption rare earth ores. It also minimizes interference between leaching agents in each step, enabling efficient leaching of rare earth elements in different occurrence states, maximizing resource utilization, and possessing high economic value.

[0018] Preferably, in step (1), the liquid-solid ratio of the first leaching agent to the ionic rare earth ore is (10-20):1, for example, it can be 10:1, 12:1, 14:1, 16:1, 18:1 or 20:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of liquid-solid ratio is mL / g.

[0019] Preferably, in step (1), the first leaching agent comprises water.

[0020] Preferably, the soaking time in step (1) is 0.5 to 1 hour, for example, it can be 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours or 1 hour, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the leaching solution in step (1) is a water-soluble rare earth leaching solution.

[0022] Preferably, the liquid-to-solid ratio of the second leaching agent in step (2) to the leaching residue obtained in step (1) is (10-20):1, for example, it can be 10:1, 12:1, 14:1, 16:1, 18:1 or 20:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of liquid-to-solid ratio is mL / g.

[0023] Preferably, in step (2), the second leaching agent comprises a magnesium chloride solution.

[0024] Preferably, the concentration of the magnesium chloride solution is 0.7 to 1 mol / L, for example, it can be 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L or 1 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the leaching in step (2) further includes adjusting the pH to 7 to 9, for example, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.2, 8.4, 8.6, 8.8 or 9, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] Preferably, the soaking time in step (2) is 0.5 to 3 hours, for example, it can be 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the leaching solution in step (2) is an exchangeable adsorbent rare earth leaching solution.

[0028] Preferably, the liquid-to-solid ratio of the third leaching agent in step (3) to the leaching residue obtained in step (2) is (10-20):1, for example, it can be 10:1, 12:1, 14:1, 16:1, 18:1 or 20:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of liquid-to-solid ratio is mL / g.

[0029] Preferably, the third leaching agent in step (3) comprises a sodium acetate solution.

[0030] Preferably, the concentration of the sodium acetate solution is 0.8 to 1 mol / L, for example, it can be 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L or 1 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the leaching in step (3) further includes adjusting the pH to 3 to 5, for example, 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8 or 5, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the soaking time in step (3) is 5 to 7 hours, for example, it can be 5 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, 6 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours or 7 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] Preferably, the leaching solution in step (3) is a carbonate rare earth leaching solution.

[0034] Preferably, the liquid-to-solid ratio of the fourth leaching agent in step (4) to the leaching residue obtained in step (3) is (15-20):1, for example, it can be 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of liquid-to-solid ratio is mL / g.

[0035] Preferably, the fourth leaching agent in step (4) comprises a sodium pyrophosphate solution.

[0036] Preferably, the concentration of the sodium pyrophosphate solution is 0.05 to 0.1 mol / L, for example, it can be 0.05 mol / L, 0.056 mol / L, 0.07 mol / L, 0.08 mol / L, 0.09 mol / L or 0.1 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the leaching in step (4) further includes adjusting the pH to 9-10, for example, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the soaking time in step (4) is 3 to 6 hours, for example, it can be 3 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours, 4 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours, 4.5 hours, 4.6 hours, 4.7 hours, 4.8 hours, 4.9 hours, 5 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, or 6 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the leaching solution in step (4) is an organically bound rare earth leaching solution.

[0040] Preferably, the liquid-to-solid ratio of the fifth leaching agent in step (5) to the leaching residue obtained in step (4) is (15-20):1, for example, it can be 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The unit of liquid-to-solid ratio is mL / g.

[0041] Preferably, the fifth leaching agent in step (5) comprises a mixed solution of hydroxylamine hydrochloride and hydrochloric acid.

[0042] Preferably, the concentration of hydroxylamine hydrochloride in the mixed solution is 0.2–0.25 mol / L, and the concentration of hydrochloric acid is 0.1–0.25 mol / L.

[0043] The concentration of hydroxylamine hydrochloride in the mixed solution described in this invention is 0.2 to 0.25 mol / L, for example, it can be 0.2 mol / L, 0.21 mol / L, 0.22 mol / L, 0.23 mol / L, 0.24 mol / L or 0.25 mol / L, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] The concentration of hydrochloric acid in the mixed solution described in this invention is 0.1–0.25 mol / L, for example, it can be 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.15 mol / L, 0.17 mol / L, 0.19 mol / L, 0.2 mol / L, 0.22 mol / L, 0.24 mol / L or 0.25 mol / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the leaching in step (5) further includes adjusting the pH to 1 to 2, for example, it can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the soaking time in step (5) is 4 to 7 hours, for example, it can be 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours or 7 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the leaching solution in step (5) is a rare earth leaching solution in the form of iron-manganese oxide.

[0048] Preferably, step (6) further includes mixing a flux with the impregnation residue obtained in step (5) before sintering.

[0049] Preferably, the mass ratio of flux to leaching residue obtained in step (5) in the mixture is (6-10):1, for example, it can be 6:1, 7:1, 8:1, 9:1 or 10:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the flux comprises sodium carbonate and / or sodium tetraborate.

[0051] Preferably, the sintering temperature in step (6) is 850–1050°C and the time is 20–40 min.

[0052] In this invention, the sintering temperature in step (6) is 850 to 1050°C, for example, it can be 850°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, 1020°C, 1040°C or 1050°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] In this invention, the sintering time in step (6) is 20 to 40 minutes, for example, it can be 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] Preferably, the acid leaching in step (6) includes: adding a mixture of sintered leaching residue and flux to hydrochloric acid to carry out a leaching reaction.

[0055] Preferably, the liquid-to-solid ratio of the hydrochloric acid to the mixture is (10-20):1, for example, it can be 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0056] Preferably, the concentration of the hydrochloric acid is 40-60%, for example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58% or 60%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the leaching reaction is carried out at a temperature of 100–150°C for 10–20 minutes.

[0058] In this invention, the leaching reaction temperature is 100-150°C, for example, it can be 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0059] Preferably, the leaching residue in step (6) includes residual rare earth elements.

[0060] Preferably, step (1) further includes sequentially crushing, drying and sieving the ion-type rare earth ore.

[0061] Preferably, the mesh size of the sieve used for sieving is 150 to 250 mesh, for example, it can be 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, 200 mesh, 210 mesh, 220 mesh, 230 mesh, 240 mesh or 250 mesh, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0062] Preferably, between step (5) and step (6), the process further includes cleaning the leaching residue obtained in step (5) with a cleaning agent and then drying it.

[0063] Preferably, the cleaning agent comprises water.

[0064] Preferably, the drying temperature is 90 to 120°C, for example, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0065] As a preferred embodiment of the stepwise extraction method of the present invention, the stepwise extraction method includes the following steps:

[0066] (1) Ionic rare earth minerals are leached with water. The liquid-solid ratio of water to ionic rare earth minerals is (10-20):1, and the unit of liquid-solid ratio is mL / g. The leaching time is 0.5-1h, and water-soluble rare earth leaching solution and leaching residue are obtained.

[0067] (2) The leaching residue obtained in step (1) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 0.7-1 mol / L to the leaching residue obtained in step (1) is (10-20):1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 7-9 during leaching, and the leaching time is 0.5-3h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0068] (3) The leaching residue obtained in step (2) is leached with sodium acetate solution. The liquid-solid ratio of the sodium acetate solution with a concentration of 0.8-1 mol / L to the leaching residue obtained in step (2) is (10-20):1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 3-5 during leaching, and the leaching time is 5-7 h to obtain carbonate rare earth leaching solution and leaching residue.

[0069] (4) The residue obtained in step (3) is leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.05-0.1 mol / L to the residue obtained in step (3) is (15-20):1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9-10 during leaching, and the leaching time is 3-6 h to obtain organically bound rare earth leaching solution and residue.

[0070] (5) The leaching residue obtained in step (4) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (4) is (15-20):1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.2-0.25 mol / L, and the concentration of hydrochloric acid is 0.1-0.25 mol / L. The concentration is adjusted to 1-2 during leaching, and the leaching time is 4-7 h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0071] (6) A flux with a mass ratio of (6-10):1 is mixed with the leaching residue obtained in step (5), wherein the flux includes sodium carbonate and / or sodium tetraborate, and then sintered at 850-1050℃ for 20-40 min. The mixture of the sintered leaching residue and the flux is then added to hydrochloric acid with a concentration of 40-60% for leaching reaction, wherein the solid-liquid ratio of the hydrochloric acid to the mixture is (10-20):1, and the leaching reaction is carried out at a temperature of 100-150℃ for 10-20 min to obtain a residual rare earth leaching solution and leaching residue.

[0072] In a second aspect, the present invention provides a rare earth solution, which is obtained by the stepwise extraction method described in the first aspect.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] The stepwise extraction method for ion-adsorption rare earth ores provided by this invention involves leaching using five different methods, followed by acid leaching of the final leaching residue after sintering, resulting in six leaching solutions and residues. This stepwise extraction method can selectively leach ion-adsorption rare earth ores with different weathering degrees, achieving a high extraction rate of rare earth elements from ion-adsorption rare earth ores. It also minimizes interference between leaching agents in each step, enabling efficient leaching of rare earth elements in different occurrence states, maximizing resource utilization, and possessing high economic value. Detailed Implementation

[0075] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0076] Example 1

[0077] This embodiment provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0078] (1) The topsoil layer with the highest degree of weathering of ion-adsorption rare earth ore with TREO of 559ppm was crushed, dried and sieved in sequence. The sieve used for sieving was 200 mesh, and the sieved ion-adsorption rare earth ore was obtained.

[0079] (2) The ion-type rare earth ore obtained in step (1) is leached with water. The liquid-solid ratio of water to ion-type rare earth ore is 15:1, the unit of liquid-solid ratio is mL / g, and the leaching time is 0.5h to obtain water-soluble rare earth leaching solution and leaching residue.

[0080] (3) The leaching residue obtained in step (2) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 0.7 mol / L to the leaching residue obtained in step (2) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 8 during leaching, and the leaching time is 2h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0081] (4) The leaching residue obtained in step (3) is leached with sodium acetate solution. The liquid-solid ratio of the sodium acetate solution with a concentration of 0.8 mol / L to the leaching residue obtained in step (3) is 10:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 5 during leaching, and the leaching time is 5h to obtain carbonate rare earth leaching solution and leaching residue.

[0082] (5) The leaching residue obtained in step (4) is leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.05 mol / L to the leaching residue obtained in step (4) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9 during leaching, and the leaching time is 5h to obtain organically bound rare earth leaching solution and leaching residue.

[0083] (6) The leaching residue obtained in step (5) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (5) is 15:1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.25 mol / L and the concentration of hydrochloric acid is 0.15 mol / L. The solution is adjusted to 1 during leaching and the leaching time is 5 h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0084] (7) The leaching residue obtained in step (6) is washed with water and then dried at 105°C to obtain the dried leaching residue.

[0085] (8) A flux with a mass ratio of 6:1 and the dried leaching residue obtained in step (7) are mixed. The flux includes sodium carbonate and sodium tetraborate with a mass ratio of 1:1. The mixture is then sintered at 950°C for 30 min. The mixture of the sintered leaching residue and the flux is then added to 50% hydrochloric acid for leaching reaction. The liquid-solid ratio of the hydrochloric acid to the mixture is 15:1. The leaching reaction is carried out at 130°C for 10 min to obtain leaching solution and residual rare earth.

[0086] Example 2

[0087] This embodiment provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0088] (1) The fully weathered layer of ion-adsorption rare earth ore with a TREO of 473 ppm was crushed, dried and sieved in sequence. The sieve used for sieving was 200 mesh, and the sieved ion-adsorption rare earth ore was obtained.

[0089] (2) The ion-type rare earth ore obtained in step (1) is leached with water. The liquid-solid ratio of water to ion-type rare earth ore is 15:1, the unit of liquid-solid ratio is mL / g, and the leaching time is 0.5h to obtain water-soluble rare earth leaching solution and leaching residue.

[0090] (3) The leaching residue obtained in step (2) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 0.7 mol / L to the leaching residue obtained in step (2) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 8 during leaching, and the leaching time is 2h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0091] (4) The leaching residue obtained in step (3) is leached with sodium acetate solution. The liquid-solid ratio of the sodium acetate solution with a concentration of 0.8 mol / L to the leaching residue obtained in step (3) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 5 during leaching, and the leaching time is 5h to obtain carbonate rare earth leaching solution and leaching residue.

[0092] (5) The leaching residue obtained in step (4) is leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.06 mol / L to the leaching residue obtained in step (4) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9 during leaching, and the leaching time is 5h to obtain organically bound rare earth leaching solution and leaching residue.

[0093] (6) The leaching residue obtained in step (5) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (5) is 15:1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.2 mol / L and the concentration of hydrochloric acid is 0.1 mol / L. The solution is adjusted to 1 during leaching and the leaching time is 5 h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0094] (7) The leaching residue obtained in step (6) is washed with water and then dried at 105°C to obtain the dried leaching residue.

[0095] (8) A flux with a mass ratio of 8:1 and the dried leaching residue obtained in step (7) are mixed. The flux includes sodium carbonate and sodium tetraborate with a mass ratio of 2:1. The mixture is then sintered at 950°C for 30 min. The mixture of the sintered leaching residue and the flux is then added to 50% hydrochloric acid for leaching reaction. The liquid-solid ratio of the hydrochloric acid to the mixture is 15:1. The leaching reaction is carried out at 130°C for 10 min to obtain leaching solution and residual rare earth.

[0096] Example 3

[0097] This embodiment provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0098] (1) The semi-weathered layer of ion-adsorption rare earth ore with a TREO of 991ppm was crushed, dried and sieved in sequence. The sieve used for sieving was 200 mesh, and the sieved ion-adsorption rare earth ore was obtained.

[0099] (2) The ion-type rare earth ore obtained in step (1) is leached with water. The liquid-solid ratio of water to ion-type rare earth ore is 20:1. The unit of liquid-solid ratio is mL / g. The leaching time is 1h. Water-soluble rare earth leaching solution and leaching residue are obtained.

[0100] (3) The leaching residue obtained in step (2) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 1 mol / L to the leaching residue obtained in step (2) is (10-20):1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9 during leaching, and the leaching time is 3h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0101] (4) The leaching residue obtained in step (3) is leached with sodium acetate solution. The liquid-solid ratio of the 1 mol / L sodium acetate solution to the leaching residue obtained in step (3) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 5 during leaching, and the leaching time is 5h to obtain carbonate rare earth leaching solution and leaching residue.

[0102] (5) The leaching residue obtained in step (4) is leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.1 mol / L to the leaching residue obtained in step (4) is 20:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9 during leaching, and the leaching time is 6h to obtain organically bound rare earth leaching solution and leaching residue.

[0103] (6) The leaching residue obtained in step (5) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (5) is 20:1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.25 mol / L and the concentration of hydrochloric acid is 0.25 mol / L. The solution is adjusted to 1 during leaching and the leaching time is 6h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0104] (7) The leaching residue obtained in step (6) is washed with water and then dried at 105°C to obtain the dried leaching residue.

[0105] (8) A flux with a mass ratio of 10:1 and the dried leaching residue obtained in step (7) are mixed. The flux includes sodium carbonate and sodium tetraborate with a mass ratio of 1:2. The mixture is then sintered at 950°C for 30 min. The mixture of the sintered leaching residue and the flux is then added to 50% hydrochloric acid for leaching reaction. The liquid-solid ratio of the hydrochloric acid to the mixture is 20:1. The leaching reaction is carried out at 150°C for 15 min to obtain leaching solution and residual rare earth.

[0106] Example 4

[0107] This embodiment provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0108] (1) The unweathered bedrock layer of ion-adsorption rare earth ore with a TREO of 324 ppm was crushed, dried and sieved in sequence. The sieve used for sieving was 200 mesh, and the sieved ion-adsorption rare earth ore was obtained.

[0109] (2) The ion-type rare earth ore obtained in step (1) is leached with water. The liquid-solid ratio of water to ion-type rare earth ore is 15:1, the unit of liquid-solid ratio is mL / g, and the leaching time is 0.5h to obtain water-soluble rare earth leaching solution and leaching residue.

[0110] (3) The leaching residue obtained in step (2) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 0.8 mol / L to the leaching residue obtained in step (2) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 8 during leaching, and the leaching time is 2h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0111] (4) The leaching residue obtained in step (3) is leached with sodium acetate solution. The liquid-solid ratio of the sodium acetate solution with a concentration of 0.8 mol / L to the leaching residue obtained in step (3) is 15:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 5 during leaching, and the leaching time is 6h to obtain carbonate rare earth leaching solution and leaching residue.

[0112] (5) The leaching residue obtained in step (4) is leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.08 mol / L to the leaching residue obtained in step (4) is 20:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9 during leaching, and the leaching time is 5h to obtain organically bound rare earth leaching solution and leaching residue.

[0113] (6) The leaching residue obtained in step (5) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (5) is 20:1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.2 mol / L and the concentration of hydrochloric acid is 0.2 mol / L. The solution is adjusted to 1 during leaching and the leaching time is 6 h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0114] (7) The leaching residue obtained in step (6) is washed with water and then dried at 105°C to obtain the dried leaching residue.

[0115] (8) A flux with a mass ratio of 10:1 and the dried leaching residue obtained in step (7) are mixed. The flux includes sodium carbonate and sodium tetraborate with a mass ratio of 1:1. The mixture is then sintered at 950°C for 30 min. The mixture of the sintered leaching residue and the flux is then added to 50% hydrochloric acid for leaching reaction. The liquid-solid ratio of the hydrochloric acid to the mixture is 20:1. The leaching reaction is carried out at 130°C for 20 min to obtain leaching solution and residual rare earth.

[0116] Example 5

[0117] This embodiment provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0118] (1) The ion-type rare earth ore is crushed, dried and sieved in sequence. The sieve used for sieving has a mesh size of 150 to obtain the sieved ion-type rare earth ore.

[0119] (2) The ion-type rare earth ore obtained in step (1) is leached with water. The liquid-solid ratio of water to ion-type rare earth ore is 10:1. The unit of liquid-solid ratio is mL / g. The leaching time is 1h. Water-soluble rare earth leaching solution and leaching residue are obtained.

[0120] (3) The leaching residue obtained in step (2) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 0.85 mol / L to the leaching residue obtained in step (2) is 10:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 7 during leaching, and the leaching time is 2h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0121] (4) The leaching residue obtained in step (3) is leached with sodium acetate solution. The liquid-solid ratio of the sodium acetate solution with a concentration of 0.9 mol / L to the leaching residue obtained in step (3) is 20:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 3 during leaching, and the leaching time is 5h to obtain carbonate rare earth leaching solution and leaching residue.

[0122] (5) The leaching residue obtained in step (4) is leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.08 mol / L to the leaching residue obtained in step (4) is 18:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 9.5 during leaching, and the leaching time is 3h to obtain organically bound rare earth leaching solution and leaching residue.

[0123] (6) The leaching residue obtained in step (5) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (5) is 18:1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.23 mol / L and the concentration of hydrochloric acid is 0.15 mol / L. The concentration is adjusted to 1.5 during leaching, and the leaching time is 4h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0124] (7) The leaching residue obtained in step (6) is washed with water and then dried at 90°C to obtain the dried leaching residue;

[0125] (8) A flux with a mass ratio of 8:1 is mixed with the dried leaching residue obtained in step (7), wherein the flux includes sodium carbonate and / or sodium tetraborate, and then sintered at 850°C for 40 min. The mixture of the sintered leaching residue and the flux is then added to 60% hydrochloric acid for leaching reaction, wherein the liquid-solid ratio of the hydrochloric acid to the mixture is 10:1, the leaching reaction temperature is 100°C, and the time is 20 min, to obtain leaching solution and residual rare earth.

[0126] Example 6

[0127] This embodiment provides a stepwise extraction method for ion-adsorption rare earth minerals, the stepwise extraction method comprising the following steps:

[0128] (1) The ion-adsorption rare earth ore is crushed, dried and sieved in sequence. The sieve used for sieving has a mesh size of 250 to obtain the sieved ion-adsorption rare earth ore.

[0129] (2) The ion-type rare earth ore obtained in step (1) is leached with water. The liquid-solid ratio of water to ion-type rare earth ore is 15:1, the unit of liquid-solid ratio is mL / g, and the leaching time is 0.6h to obtain water-soluble rare earth leaching solution and leaching residue.

[0130] (3) The leaching residue obtained in step (2) is leached with magnesium chloride solution. The liquid-solid ratio of the magnesium chloride solution with a concentration of 0.85 mol / L to the leaching residue obtained in step (2) is 16:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 8 during leaching, and the leaching time is 0.5 h to obtain exchangeable adsorbed rare earth leaching solution and leaching residue.

[0131] (4) The leaching residue obtained in step (3) is leached with sodium acetate solution. The liquid-solid ratio of the sodium acetate solution with a concentration of 0.92 mol / L to the leaching residue obtained in step (3) is 13:1. The unit of liquid-solid ratio is mL / g. The pH is adjusted to 4 during leaching, and the leaching time is 7h to obtain carbonate rare earth leaching solution and leaching residue.

[0132] (5) The leaching residue obtained in step (4) was leached with sodium pyrophosphate solution. The liquid-solid ratio of the sodium pyrophosphate solution with a concentration of 0.08 mol / L to the leaching residue obtained in step (4) was 16:1. The unit of liquid-solid ratio was mL / g. The pH was adjusted to 10 during leaching, and the leaching time was 3.2 h to obtain organically bound rare earth leaching solution and leaching residue.

[0133] (6) The leaching residue obtained in step (5) is leached with the fifth leaching agent. The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (5) is 16:1. The unit of the liquid-solid ratio is mL / g. The fifth leaching agent includes a mixed solution of hydroxylamine hydrochloride and hydrochloric acid. The concentration of hydroxylamine hydrochloride in the mixed solution is 0.24 mol / L and the concentration of hydrochloric acid is 0.16 mol / L. The solution is adjusted to 2 during leaching and the leaching time is 7h to obtain iron-manganese oxide rare earth leaching solution and leaching residue.

[0134] (7) The leaching residue obtained in step (6) is washed with water and then dried at 120°C to obtain the dried leaching residue;

[0135] (8) A flux with a mass ratio of 8:1 and the dried leaching residue obtained in step (7) are mixed. The flux includes sodium carbonate and / or sodium tetraborate. The mixture is then sintered at 1050°C for 20 min. The mixture of the sintered leaching residue and the flux is then added to 40% hydrochloric acid for leaching reaction. The liquid-solid ratio of the hydrochloric acid to the mixture is 12:1. The leaching reaction is carried out at 130°C for 16 min to obtain leaching solution and residual rare earth.

[0136] Example 7

[0137] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of water to sieved ionic rare earth minerals in step (2), which is 5:1, the rest is the same as in embodiment 1.

[0138] Example 8

[0139] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of water to sieved ionic rare earth minerals in step (2), which is 30:1, the rest is the same as in embodiment 1.

[0140] Example 9

[0141] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the concentration of magnesium chloride solution in step (3) being 0.5 mol / L, the rest is the same as in Example 1.

[0142] Example 10

[0143] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the concentration of magnesium chloride solution in step (3) being 1.2 mol / L, the rest is the same as in Example 1.

[0144] Example 11

[0145] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of magnesium chloride solution to leaching residue obtained in step (2) being 5:1, the rest is the same as in Example 1.

[0146] Example 12

[0147] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of magnesium chloride solution to leaching residue obtained in step (2) being 30:1, the rest is the same as in Example 1.

[0148] Example 13

[0149] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the concentration of sodium acetate solution in step (4) being 0.6 mol / L, the rest is the same as in Example 1.

[0150] Example 14

[0151] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the concentration of sodium acetate solution in step (4) being 1.2 mol / L, the rest is the same as in Example 1.

[0152] Example 15

[0153] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of sodium acetate solution to leaching residue obtained in step (3) being 15:1, the rest is the same as in Example 1.

[0154] Example 16

[0155] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of sodium acetate solution to leaching residue obtained in step (3) being 25:1, the rest is the same as in Example 1.

[0156] Example 17

[0157] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the concentration of sodium pyrophosphate solution in step (5) being 0.02 mol / L, the rest is the same as in Example 1.

[0158] Example 18

[0159] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the concentration of sodium pyrophosphate solution in step (5) being 0.15 mol / L, the rest is the same as in Example 1.

[0160] Example 19

[0161] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of sodium pyrophosphate solution to leaching residue obtained in step (4) being 10:1, the rest is the same as in Example 1.

[0162] Example 20

[0163] This embodiment provides a stepwise extraction method for ionic rare earth minerals. Except for the liquid-solid ratio of sodium pyrophosphate solution to leaching residue obtained in step (4) being 25:1, the rest is the same as in Example 1.

[0164] The rare earth elements in the water-soluble rare earth leaching solution obtained in step (2), the exchangeable adsorbed rare earth leaching solution obtained in step (3), the carbonate rare earth leaching solution obtained in step (4), the organically bound rare earth leaching solution obtained in step (5), the iron-manganese oxide rare earth leaching solution obtained in step (6), and the leaching solution obtained in step (8) of Examples 1 to 20 were tested and summed to obtain the final rare earth leaching rate as shown in Table 1.

[0165] Table 1

[0166]

[0167]

[0168] From Table 1, we can obtain:

[0169] (1) In the stepwise extraction method of ionic rare earth ore in Examples 1 to 6, five leaching methods are used for leaching, and the leaching residue is sintered and acid-leached to obtain six leaching solutions and leaching residue. The stepwise extraction method can selectively leach ionic rare earth ore with different weathering degrees and has a high extraction rate of rare earth in ionic rare earth ore.

[0170] (2) By comparing Example 1 with Examples 7 and 8, it can be seen that the liquid-solid ratio of the first leaching agent to the ionic rare earth ore affects the rare earth leaching rate. When the liquid-solid ratio of the first leaching agent to the ionic rare earth ore is too low, the rare earth leaching rate will be too low. This is because the amount of the first leaching agent added is too small, so that the hydrated rare earth ions in the ore soil cannot be extracted. When the liquid-solid ratio of the first leaching agent to the ionic rare earth ore is too high, the rare earth leaching rate will be too low. This is because the addition of excessive first leaching agent will increase the pH of the ore soil. Excessive pH will affect the leaching of rare earth. It is more conducive to the extraction of rare earth elements at a lower pH.

[0171] (3) By comparing Example 1 with Examples 9 and 10, it can be seen that the concentration of magnesium chloride solution affects the rare earth leaching rate. When the concentration of magnesium chloride solution is too low, the rare earth leaching rate will be too low. This is because the concentration of magnesium chloride solution is too low, the exchange of rare earth elements is incomplete, and it is difficult to extract all the rare earth elements in the ore. When the concentration of magnesium chloride solution is too high, the rare earth leaching rate will be too low. This is because the extracted rare earth elements will be reverse adsorbed under high concentration magnesium chloride solution, causing the rare earth elements to be adsorbed into the ore again.

[0172] (4) By comparing Example 1 with Examples 11 and 12, it can be seen that the liquid-solid ratio of the second leaching agent to the leaching residue obtained in the previous step (10-20):1 will affect the rare earth leaching rate. When the liquid-solid ratio of the second leaching agent to the leaching residue obtained in the previous step is too low, the rare earth leaching rate will be too low. This is because the content of the leaching residue is too high, and the second leaching agent has not completed the reaction with the leaching residue. When the liquid-solid ratio of the second leaching agent to the leaching residue obtained in the previous step is too high, the rare earth leaching rate will be too low. This is because the concentration of other impurity ions leached by the excessive second leaching agent is high. Impurity ions represented by Al and Fe affect the leaching of rare earth, making it difficult for rare earth to be leached efficiently in a high-concentration solution system.

[0173] (5) By comparing Example 1 with Examples 13 and 14, it can be seen that the concentration of sodium acetate solution affects the rare earth leaching rate. When the concentration of sodium acetate solution is too low, the rare earth leaching rate will be too low. This is because the reaction between sodium acetate solution and rare earth is incomplete, and rare earth cannot be fully leached. When the concentration of sodium acetate solution is too high, the rare earth leaching rate will be too low. This is because excessively high concentrations of sodium acetate will cause the leached rare earth to form complexes, making it difficult to leach and extract.

[0174] (6) By comparing Example 1 with Examples 15 and 16, it can be seen that the liquid-solid ratio of the third leaching agent to the leaching residue obtained in the previous step affects the rare earth leaching rate. When the liquid-solid ratio of the third leaching agent to the leaching residue obtained in the previous step is low, the rare earth leaching rate will be low because the third leaching agent cannot react fully with the leaching residue, and the amount of rare earth exchanged is small. When the liquid-solid ratio of the third leaching agent to the leaching residue obtained in the previous step is high, the rare earth leaching rate will be low because the addition of excessive leaching agent results in excessive impurities being leached, which inhibits the leaching of rare earth.

[0175] (7) By comparing Example 1 with Examples 17 and 18, it can be seen that the concentration of sodium pyrophosphate solution affects the rare earth leaching rate. When the concentration of sodium pyrophosphate solution is too low, the rare earth leaching rate will be too low. This is because the reaction between sodium pyrophosphate solution and rare earth is incomplete, and rare earth cannot be fully leached. When the concentration of sodium pyrophosphate solution is too high, the rare earth leaching rate will be too low. This is because sodium pyrophosphate disrupts the acid-base balance of the leaching solution, making it difficult for rare earth to be leached in large quantities in the leaching system.

[0176] (8) By comparing Example 1 with Examples 19 and 20, it can be seen that the liquid-solid ratio of the fourth leaching agent to the leaching residue obtained in the previous step affects the rare earth leaching rate. When the liquid-solid ratio of the fourth leaching agent to the leaching residue obtained in the previous step is low, the rare earth leaching rate will be low. This is because the reaction between the fourth leaching agent and the rare earth is incomplete, and the rare earth cannot be fully leached. When the liquid-solid ratio of the fourth leaching agent to the leaching residue obtained in the previous step is high, the rare earth leaching rate will be low. This is because the addition of excessive leaching agent changes the equilibrium state of the leaching system. Rare earth cations are unstable in the high-concentration system and are difficult to be leached efficiently.

[0177] In summary, the stepwise extraction method for ion-adsorption rare earth ores provided by this invention involves leaching using five different methods, followed by acid leaching of the final leaching residue after sintering, resulting in six leaching solutions and residues. This stepwise extraction method enables selective leaching of ion-adsorption rare earth ores with varying degrees of weathering, achieving a high extraction rate of rare earth elements. It also minimizes interference between leaching agents in each step, allowing for efficient leaching of rare earth elements in different occurrence states, maximizing resource utilization, and possessing significant economic value.

[0178] The above description is only a specific embodiment 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 conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for the stepwise extraction of ion-type rare earth ores, characterized in that, The step-by-step extraction method comprises the following steps: (1) leaching the ionic rare earth ore with a first leaching agent to obtain a water-soluble rare earth leaching solution and a leaching residue; the first leaching agent comprises water; (2) leaching the leaching residue obtained in step (1) with a second leaching agent to obtain an exchangeable adsorption state rare earth leaching solution and a leaching residue; the second leaching agent comprises a magnesium chloride solution; (3) leaching the leaching residue obtained in step (2) with a third leaching agent to obtain a carbonate state rare earth leaching solution and a leaching residue; the third leaching agent comprises a sodium acetate solution; (4) leaching the leaching residue obtained in step (3) with a fourth leaching agent to obtain an organic combination state rare earth leaching solution and a leaching residue; the fourth leaching agent comprises a sodium pyrophosphate solution; (5) leaching the leaching residue obtained in step (4) with a fifth leaching agent to obtain an iron and manganese oxide state rare earth leaching solution and a leaching residue; the fifth leaching agent comprises a mixed solution of hydroxylamine hydrochloride and hydrochloric acid; (6) performing acid leaching on the leaching residue obtained in step (5) after sintering to obtain a leaching solution and a residue state rare earth.

2. The fractional extraction method of claim 1, wherein, The liquid-solid ratio of the first leaching agent to the ionic rare earth ore in step (1) is (10-20):1, and the unit of the liquid-solid ratio is mL / g.

3. The fractional extraction method of claim 1, wherein, The leaching time in step (1) is 0.5-1 h.

4. The fractional extraction method of claim 1, wherein, The liquid-solid ratio of the second leaching agent to the leaching residue obtained in step (1) in step (2) is (10-20):1, and the unit of the liquid-solid ratio is mL / g.

5. The fractional extraction method of claim 1, wherein, The concentration of the magnesium chloride solution is 0.7-1 mol / L.

6. The fractional extraction method of claim 1, wherein, The leaching in step (2) further comprises adjusting the pH to 7-9.

7. The fractional extraction method of claim 1, wherein, The leaching time in step (2) is 0.5-3 h.

8. The fractional extraction method of claim 1, wherein, The liquid-solid ratio of the third leaching agent to the leaching residue obtained in step (2) in step (3) is (10-20):1, and the unit of the liquid-solid ratio is mL / g.

9. The fractional extraction method of claim 1, wherein, The concentration of the sodium acetate solution is 0.8-1 mol / L.

10. The fractional extraction method of claim 1, wherein, The leaching in step (3) further comprises adjusting the pH to 3-5.

11. The fractional extraction method of claim 1, wherein, The leaching time in step (3) is 5-7 h.

12. The fractional extraction method of claim 1, wherein, The liquid-solid ratio of the fourth leaching agent to the leaching residue obtained in step (3) in step (4) is (15-20):1, and the unit of the liquid-solid ratio is mL / g.

13. The fractional extraction method of claim 1, wherein, The concentration of the sodium pyrophosphate solution is 0.05-0.1 mol / L.

14. The fractional extraction method of claim 1, wherein, The leaching in step (4) further comprises adjusting the pH to 9-10.

15. The fractional extraction method of claim 1, wherein, The leaching time in step (4) is 3-6 h.

16. The fractional extraction method of claim 1, wherein, The liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (4) in step (5) is (15-20):1, and the unit of the liquid-solid ratio is mL / g.

17. The fractional extraction method of claim 1, wherein, The concentration of hydroxylamine hydrochloride in the mixed solution is 0.2-0.25 mol / L, and the concentration of hydrochloric acid is 0.1-0.25 mol / L.

18. The fractional extraction method of claim 1, wherein, The leaching in step (5) further comprises adjusting the pH to 1-2.

19. The fractional extraction method of claim 1, wherein, The leaching time in step (5) is 4-7 h.

20. The fractional extraction method of claim 1, wherein, The sintering in step (6) further comprises mixing a fluxing agent with the leaching residue obtained in step (5).

21. The fractionation process of claim 20, wherein, The mass ratio of the fluxing agent to the leaching residue obtained in step (5) in the mixing is (6-10):

1.

22. The fractional extraction method of claim 20, wherein, The fluxing agent comprises sodium carbonate and / or sodium tetraborate.

23. The fractional extraction method of claim 1, wherein, The sintering temperature in step (6) is 850-1050°C, and the time is 20-40 min.

24. The fractional extraction method of claim 1, wherein, The acid leaching in step (6) comprises: adding the mixture of the sintered leaching residue and fluxing agent into hydrochloric acid to perform leaching reaction.

25. The fractionation process of claim 24, wherein, The liquid-solid ratio of the hydrochloric acid to the mixture is (10-20):1, and the unit of the liquid-solid ratio is mL / g.

26. The fractionation process of claim 24, wherein, The concentration of the hydrochloric acid is 40-60%.

27. The fractional extraction method of claim 24, wherein, The temperature of the leaching reaction is 100-150 DEG C, and the time is 10-20 min.

28. The fractional extraction method of claim 1, wherein, Before step (1), the ion-type rare earth ore is sequentially subjected to crushing, drying and sieving.

29. The fractional extraction method of claim 1, wherein, Between step (5) and step (6), the leaching residue obtained in step (5) is washed with a cleaning agent and then dried.

30. The fractional extraction method of claim 29, wherein, The temperature of the drying is 90-120 DEG C.

31. The fractional extraction method of claim 1, wherein, The step-by-step extraction method comprises the following steps: (1) leaching the ion-type rare earth ore with water, the liquid-solid ratio of the water to the ion-type rare earth ore is (10-20):1, the unit of the liquid-solid ratio is mL / g, the leaching time is 0.5-1 h, to obtain water-soluble rare earth leaching solution and leaching residue; (2) leaching the leaching residue obtained in step (1) with magnesium chloride solution, the liquid-solid ratio of the 0.7-1 mol / L magnesium chloride solution to the leaching residue obtained in step (1) is (10-20):1, the unit of the liquid-solid ratio is mL / g, the pH is adjusted to 7-9 during leaching, the leaching time is 0.5-3 h, to obtain exchangeable and adsorbed state rare earth leaching solution and leaching residue; (3) leaching the leaching residue obtained in step (2) with sodium acetate solution, the liquid-solid ratio of the 0.8-1 mol / L sodium acetate solution to the leaching residue obtained in step (2) is (10-20):1, the unit of the liquid-solid ratio is mL / g, the pH is adjusted to 3-5 during leaching, the leaching time is 5-7 h, to obtain carbonate state rare earth leaching solution and leaching residue; (4) leaching the leaching residue obtained in step (3) with sodium pyrophosphate solution, the liquid-solid ratio of the 0.05-0.1 mol / L sodium pyrophosphate solution to the leaching residue obtained in step (3) is (15-20):1, the unit of the liquid-solid ratio is mL / g, the pH is adjusted to 9-10 during leaching, the leaching time is 3-6 h, to obtain organic combined state rare earth leaching solution and leaching residue; (5) leaching the leaching residue obtained in step (4) with a fifth leaching agent, the liquid-solid ratio of the fifth leaching agent to the leaching residue obtained in step (4) is (15-20):1, the unit of the liquid-solid ratio is mL / g, the fifth leaching agent comprises a mixed solution of hydroxylamine hydrochloride and hydrochloric acid, the concentration of the hydroxylamine hydrochloride in the mixed solution is 0.2-0.25 mol / L, the concentration of the hydrochloric acid is 0.1-0.25 mol / L, the pH is adjusted to 1-2 during leaching, the leaching time is 4-7 h, to obtain iron-manganese oxide state rare earth leaching solution and leaching residue; (6) mixing fluxing agent with the leached residue obtained in step (5) in a mass ratio of (6-10):1, the fluxing agent comprising sodium carbonate and / or sodium tetraborate, and sintering the mixture at 850-1050°C for 20-40 min, then adding the sintered mixture of leached residue and fluxing agent into hydrochloric acid with a concentration of 40-60% for leaching, the liquid-solid ratio of the hydrochloric acid to the mixture being (10-20):1, the unit of liquid-solid ratio being mL / g, the leaching temperature being 100-150°C, and the leaching time being 10-20 min, to obtain leaching solution and residual rare earth in residue form.

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