Mining, mineral separation and smelting preparation method of ionic rare earth

Abstract

The invention provides a mining-mineral separation-smelting short-process preparation method of ionic rare earth, and belongs to the technical field of rare earth preparation. The method comprises the following steps: separating monovalent and high-valence ions from a pretreated clear liquid of the ionic rare earth leaching mother liquid to obtain a permeate liquid and a cut-off liquid; the permeate liquid is returned to the mineral leaching agent for cyclic utilization; the trapped fluid is subjected to multi-stage concentration to generate a rare earth concentrated solution which is directly used for rare earth refining; sequentially adding an extraction agent and a back extraction agent into the rare earth concentrated solution to obtain a rare earth concentrated solution; and refining the rare earth concentrated solution to obtain the ionic rare earth. The invention relates to an integrated membrane separation technology formed by nanofiltration without adding a chemical precipitator and a multi-stage reverse osmosis membrane, and the integrated membrane separation technology is used for updating the traditional processes of in-situ rare earth ore leaching, chemical impurity removal, chemical precipitation and acid dissolution-extraction rare earth separation and purification and replacing a clean production process. The technological processes of mining, mineral separation and smelting of the ionic rare earth are simplified, the cost is reduced, and the recovery rate of the rare earth is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth preparation, and in particular to a method for preparing ionic rare earths, which can be specifically a short-process preparation method of ionic rare earths including mining, beneficiation and smelting. Background Art

[0002] Ionic rare earth is a medium-heavy rare earth adsorbed in the soil of rare earth mines in ionic form. The current mining, beneficiation and smelting processes of ionic rare earth are as follows (e.g. Figure 1 As shown): Clearing vegetation in rare earth mines - manual drilling - in-situ injection of leachate - chemical removal of rare earth mother liquor - chemical precipitation - solid-liquid separation - solid rare earth acid dissolution - extraction separation and purification. First, the vegetation on the surface of the rare earth mine is removed manually, and then holes are drilled manually with a Luoyang shovel according to a certain distribution; then the prepared leachate is drip-irrigated into the holes dug in the rare earth mine, and the ionic rare earths adsorbed in the soil are replaced and leached through ion exchange to obtain rare earth leaching mother liquor; the rare earth mother liquor is collected and pumped into a rare earth mother liquor collection pool with a pump, and a low concentration of sodium bicarbonate (or ammonium bicarbonate) is added. After pneumatic stirring and reaction, it is allowed to settle. Impurities such as aluminum ions and silicon are removed in the form of precipitation, and the supernatant after impurities removal enters the chemical precipitation tank; to An excess of high-concentration sodium bicarbonate (or ammonium bicarbonate) precipitant and coagulant aid is added to the chemical precipitation tank to obtain rare earth carbonate precipitation. The supernatant of the chemical precipitation tank is returned to the leaching solution preparation reuse water tank, and the rare earth carbonate precipitated at the bottom of the precipitation tank is sent to the solid-liquid separation workshop, and the rare earth carbonate solid is obtained after solid-liquid separation by plate and frame filtration; the rare earth carbonate solid is transported to the rare earth smelter, first dissolved in acid to form a rare earth solution, and then an extractant is added, and the ionic rare earth enters the extraction phase, and then after back extraction, a high-concentration rare earth concentrate is obtained, thereby achieving the purpose of separation and purification of ionic rare earths.

[0003] This process involves chemical impurity removal of rare earth mother liquor and chemical precipitation stages, which consume a large amount of chemical precipitants; it is necessary to build a large-capacity chemical precipitation reaction tank; it is also necessary to be equipped with a reagent preparation tank and special reagent configuration personnel; each precipitation reaction tank needs to be equipped with multiple operators for reagent addition and solid-liquid separation; the separation of rare earth precipitate and supernatant depends entirely on the personal experience of the operator; when rare earth carbonate is smelted, acid is used to dissolve the rare earth carbonate into an ionic state, and a large amount of high-salt wastewater is also produced; in this mining, mineral processing and smelting process, rare earth ions need to undergo a transformation from liquid ions to solid precipitates, and then from solid precipitates to ions. The process is very long and requires the consumption of a large amount of chemical impurity removers and precipitants. In multiple separation stages, it depends entirely on the personal experience of the operator. It often happens that rare earth carbonate precipitates (small particles) that cannot be completely precipitated in the supernatant of the chemical sedimentation tank are discharged into the leaching solution water reuse pool and returned to the soil of the rare earth mine through leaching drip irrigation. These rare earth precipitates are difficult to be leached again by the rare earth leaching solution, resulting in the loss of a large amount of rare earths in the rare earth mine.

[0004] At present, there are a large number of patent applications for the mining, beneficiation and smelting of ionic rare earths, mainly focusing on in-situ leaching, leaching solution impurity removal, rare earth mine restoration, tailings treatment, rare earth smelting wastewater treatment, etc. For example, the invention patent with application number: CN202211195950.5 discloses a cascade liquid collection method: according to the geological conditions of the ionic rare earth mining area, each layer of leaching diversion holes, leaching collection ditches and rainwater drainage ditches are constructed according to volume division, and the leaching liquid seeps into the leaching diversion holes of each layer set in the ore body, and finally gathers in the seepage collection well at the foot of the mountain. The leaching liquid after separation and purification is returned to the mining area for injection. For example, the invention patent with application number CN201911023135.9 discloses a device for intercepting and collecting liquid for in-situ leaching of ionic rare earths and its use method. A receiving female port and an insertable male head are respectively provided at both ends of a collecting pipe, and interception butterfly wings and a hydrophobic net are provided upward on both sides of the collecting pipe, so that the rare earth leachate flowing downward is intercepted and collected through the V-shaped guide grooves connected in series by the upper and lower multi-layer interception and liquid collection devices. For example, the invention patent with application number CN202410765206.7 discloses a device for electric enhanced leaching test of ionic rare earths, which uses the electric action of an external electric field to promote the desorption of ions and accelerate the seepage of the solution, thereby realizing the rapid leaching of ionic rare earths. For example, the invention patent with application number CN202223266604.X discloses a system for purifying rare earths from ionic rare earth ores, including a pretreatment device, an ion adsorption device and a precipitation recovery device. The pretreatment device first pre-treats the rare earth ore, and then separates and enriches the rare earth ore through an adsorption device filled with ion exchange resin. After the resin is saturated with adsorption, it is desorbed to achieve continuous separation and enrichment of the rare earth ore. For example, the invention patent with application number CN202323474978.5 discloses a permeable reaction system for the remediation of groundwater pollution in ionic rare earth mining areas. By setting a first transition zone, a second transition zone, a denitrification zone, a third transition zone, an adsorption zone and a fourth transition zone in the underground of the mining area, the in-situ remediation of groundwater pollution in the mining area is achieved. For example, the invention patent with application number CN202111642307.8 discloses a method for recovering valuable elements in the slag produced by chemical precipitation and impurity removal of rare earth leaching solution, first leaching with concentrated sulfuric acid, filtering to obtain rare earth, aluminum, uranium and thorium leaching solution, and then extracting to achieve the recovery of valuable elements.For example, the invention patent with application number CN202410645819.7 discloses a green mining method for ion-type rare earth ore leaching, smelting and leaching. The leaching tail water, the supernatant of water smelting membrane concentration and the leaching agent are mixed to obtain the leaching liquid, which is injected into the leaching field for leaching. The leaching mother liquor is collected by collecting the liquid, and the mother liquor is dealuminized by the dealuminizing agent, and reacts with the precipitant to separate the solid and liquid to obtain the rare earth product and the water smelting supernatant. The supernatant is membrane concentrated to obtain the water smelting supernatant membrane concentrated liquid and the water smelting supernatant membrane concentrated fresh water. The membrane concentrated fresh water is reinjected for leaching. The membrane concentrated fresh water obtained by different leaching times is reused in stages, and the leaching tail water is used for leaching, saving the amount of leaching agent and acid. For example, the invention patent with application number CN202210392497.0 discloses a curing agent for abandoned mines of ionic rare earth in-situ leaching. This curing agent and the solidification of rare earth in-situ leaching waste can effectively solve the problem of soft soil and prevent landslides. For example, the invention patent with application number CN202410211498.X discloses a method for stabilizing the in-situ leaching and mineralization of thallium in an ionic rare earth leaching field, which performs in-situ leaching of the leaching field, thallium treatment of the leaching tail water, in-situ mineralization stabilization and backfilling repair, and solves the release of thallium from the source. For example, the invention patent with application number CN2024102462248.X discloses a green mining method for ionic rare earth ores, in which the leaching solution is injected into the leaching field for in-situ leaching to obtain a leaching mother liquor. The leaching water is injected into the leaching field after leaching to obtain a leaching solution. The leaching mother liquor and the leaching mother liquor are mixed to obtain a mother liquor, and then the aluminum removal treatment is performed to obtain an aluminum removal liquid, which is precipitated to obtain a precipitated liquid and a rare earth product. The precipitated liquid is further decalcified to obtain a decalcified liquid, and the concentrated liquid obtained by acid adjustment and membrane concentration is used as a leaching liquid, and fresh water is used as leaching water. Improve the quality of rare earth products, recover rare earth and leaching agent in the leaching tail liquid, and reduce the risk of water environment pollution. For example, the invention patent with application number CN202410033133.2 discloses a waste-free mining method for in-situ double salt leaching and leaching of ionic rare earth mines, selects an inorganic sulfate compound leaching agent, performs in-situ leaching through a liquid injection system, uses an aluminum-enriched agent to remove aluminum ions, and uses carbonates to precipitate rare earths. No new cations are introduced, and there is no ammonia nitrogen pollution problem. For example, the invention patent with application number CN202410812057.5 discloses a method for preparing ammonium chloride by evaporating high-salt wastewater from ionic rare earth separation. Alkaline substances are added to the high-salt wastewater from ionic rare earth separation to obtain pretreated wastewater with impurities removed, and evaporated and crystallized to obtain ammonium chloride products and crystallization mother liquors. The organic phase containing the extractant is extracted and phase-separated to obtain a raffinate, which is then returned to the pretreated wastewater for evaporation and crystallization.For example, the invention patent with application number CN202311394195.8 discloses a precipitation-organic extraction enrichment process for ionic rare earth leaching mother liquor. Calcium and magnesium compounds are added to the leaching mother liquor to adjust the pH value to 5.1-5.4, and the supernatant is taken and the precipitation pH is controlled to 7.5-8.5 with calcium and magnesium compounds until the rare earth is completely precipitated. After solid-liquid separation, extraction and stripping, a rare earth liquid with a rare earth concentration greater than 200g / L is obtained, which meets the requirements of rare earth smelting and separation. Xin Yuntao (CN202410043785.4) applied for an ionic rare earth leaching and enrichment process: inject a leaching agent into the ore body to obtain a leaching mother liquor, filter the low-concentration mother liquor with a concentration of less than 1g / L through a filtration device to obtain a concentrate 1 and a permeate 1, filter the membrane permeate again to obtain a concentrate 2 and a permeate 2, mix the concentrate 1 and 2 to obtain an enriched solution, add a chemical precipitant when the concentration is greater than 1g / L to produce a rare earth product, and return the supernatant to the leaching ore. The permeate 1 and the permeate 2 are mixed and returned to the leaching ore. For example, Wang Zhigao (Hydrometallurgy, 2014, 33(6): 469-472) pretreated the rare earth mother liquor leached from ammonium sulfate with a ceramic membrane, and then concentrated it with a nanofiltration membrane, and the rare earth content was enriched from 0.46g / l to 4.23g / l.

[0005] From the above-mentioned disclosed invention patents and papers, some are about developing new or compound ionic rare earth leaching agents; some are about graded utilization and graded recovery of leaching water; some are about solving the risk of seepage of thallium pollutants after in-situ leaching, loose mountains and other geological hazards, and proposing some in-situ solidification of thallium and mountain soil solidification agents. There are also membrane concentration of leachate to increase the concentration of chemical precipitation; there are also membrane treatment of the supernatant after chemical precipitation and return of water to leaching; some are preparation methods for ammonium chloride products of high-salt wastewater produced in the smelting section. Wang Zhigao used ultrafiltration membrane and nanofiltration for concentration, but the rare earth concentration multiple was low, and it was difficult to meet the concentration requirements of the smelting process. All the above-mentioned disclosed invention patents are the same as the current traditional ionic rare earth leaching, mining and smelting processes, with only some minor adjustments. These traditional mining, beneficiation and smelting processes generally have the following disadvantages: long process flow, rare earth products need to undergo multiple physical changes, low rare earth recovery rate, incomplete solid-liquid separation in chemical precipitation tanks leading to rare earth loss, etc. Summary of the invention

[0006] In view of this, in order to solve the technical problems of long preparation process flow of ionic rare earths, low rare earth recovery rate, and incomplete solid-liquid separation in chemical precipitation tanks leading to rare earth loss in the prior art, the present invention provides a preparation method for mining, beneficiation and smelting of ionic rare earths, using an integrated membrane separation technology composed of nanofiltration and multi-stage reverse osmosis membranes without the need for adding external chemical reagents, and using the integrated membrane separation technology to update and replace the traditional in-situ rare earth leaching, chemical precipitation and acid dissolution-extraction rare earth separation and purification traditional processes, simplify the process flow of mining, beneficiation and smelting of ionic rare earths, reduce production costs, improve the recovery rate of rare earths and reduce losses.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing ionic rare earth comprises the following steps:

[0009] Step (1), the clear liquid obtained after pre-treatment of the ionic rare earth leaching mother liquid is subjected to separation of monovalent ions and high-valent ions to obtain a permeate and a interception liquid respectively;

[0010] Step (2), the permeate is returned to the leaching agent water distribution tank for use in the preparation of the leaching agent, so as to achieve full reuse of the production water; the retentate is subsequently concentrated by a multi-stage reverse osmosis membrane to obtain a rare earth concentrate, which is directly subjected to rare earth extraction;

[0011] Step (3), extracting and stripping the rare earth concentrate in step (2) in sequence to obtain a rare earth concentrate;

[0012] Step (4), refining the rare earth concentrate in step (3) to obtain ionic rare earth.

[0013] Preferably, in step (2), the multi-stage reverse osmosis membrane concentration is determined according to the concentration of rare earth ions in the retentate.

[0014] Preferably, in step (2), the multi-stage reverse osmosis membrane concentration is a four-stage reverse osmosis membrane concentration.

[0015] Preferably, the four-stage reverse osmosis membrane concentration comprises:

[0016] First-stage reverse osmosis membrane concentration: When the rare earth ion concentration is lower than 0.5g / l, a low-pressure, high-flux reverse osmosis membrane element is used;

[0017] Second stage reverse osmosis membrane concentration: When the rare earth ion concentration is concentrated to 1.2g / l, a medium pressure high rejection rate reverse osmosis membrane is used;

[0018] The third stage reverse osmosis membrane concentration: when the rare earth ion concentration is concentrated to 2.4g / l, a high pressure and high retention rate reverse osmosis membrane is used;

[0019] Fourth-stage reverse osmosis membrane concentration: When the rare earth ion content exceeds 4g / l, a disc-tube ultra-high pressure reverse osmosis membrane is used.

[0020] Preferably, the first stage reverse osmosis membrane concentration operating pressure is 1.0-1.6MPa;

[0021] The operating pressure of the second-stage reverse osmosis membrane concentration is 1.5-2.5MPa;

[0022] The operating pressure of the third-stage reverse osmosis membrane concentration is 2.0-4.5MPa;

[0023] The operating pressure of the fourth stage reverse osmosis membrane concentration is 4.0-7.5MPa.

[0024] Preferably, the produced water concentrated by the second stage reverse osmosis membrane is returned to the first stage reverse osmosis membrane for concentration;

[0025] The produced water concentrated by the third-stage reverse osmosis membrane is returned to the second-stage reverse osmosis membrane for concentration;

[0026] The produced water concentrated by the fourth stage reverse osmosis membrane is returned to the third stage reverse osmosis membrane for concentration;

[0027] The produced water concentrated by the first stage reverse osmosis membrane is returned to the water pool for preparing the leaching agent.

[0028] Preferably, in step (1), a nanofiltration membrane is used to separate monovalent ions and high-valent ions.

[0029] Preferably, the operating pressure of the nanofiltration membrane is 0.4-1.2 MPa.

[0030] Preferably, in step (3), the extractant is directly added to the rare earth concentrate for separation and purification without adding acid for dissolution.

[0031] Preferably, in step (1), the pretreatment is gravity impurity removal.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The preparation method of ionic rare earth provided by the present invention uses an integrated membrane separation technology composed of nanofiltration and multi-stage reverse osmosis membranes without the need for adding external chemical reagents, and utilizes the integrated membrane separation technology to update and replace the traditional in-situ rare earth leaching, chemical precipitation and acid dissolution-extraction rare earth separation and purification traditional processes with clean production processes, thereby simplifying the process flow of ionic rare earth mining, ore dressing and smelting, reducing production costs, improving the recovery rate of rare earths and reducing losses.

[0034] The present invention takes ionic rare earth leaching mother liquor as the object, and the supernatant after gravity impurity removal is first separated from monovalent ions and high-valent ions by nanofiltration membrane, and the high-valent rare earth ions intercepted by the nanofiltration membrane are then concentrated by multi-stage reverse osmosis membrane, and the first-stage reverse osmosis membrane concentrates and produces water to return to the leaching agent for recycling; the multi-stage reverse osmosis membrane selects low pressure (first-stage reverse osmosis membrane concentration), medium pressure (second-stage reverse osmosis membrane concentration), high pressure (third-stage reverse osmosis membrane concentration) and ultra-high pressure (fourth-stage reverse osmosis membrane concentration) reverse osmosis membrane cascade integration according to the rare earth concentration, and the rare earth concentrated liquid obtained is directly sent to the rare earth smelter to add the extractant to separate and purify the rare earth. The mining, ore dressing and smelting process provided by the present invention only uses nanofiltration and reverse osmosis membrane, does not add chemical precipitants and flocculants, does not need to build chemical precipitation tanks and aeration devices, and greatly saves rare earth ion chemical impurity removers, precipitants, infrastructure investment and labor costs. The rare earth leaching mother liquor is directly separated and concentrated by an integrated membrane, and the concentrated liquor is sent to the extraction section, which reduces the chemical impurity removal, chemical precipitation, plate and frame filtration and rare earth carbonate acid dissolution sections, reduces the amount of rare earth chemical impurity removers, precipitants, and rare earth dissolving acids, greatly simplifies the mining, beneficiation and smelting process of ionic rare earths, and greatly reduces the production cost of ionic rare earths.

[0035] The present invention does not require the addition of external chemical reagents. The produced water obtained by integrated membrane concentration is reused in the preparation of leaching agents, and the kerosene in the extraction section will not be brought into the mine, thus avoiding the serious harm to the ecological environment caused by the return of kerosene to the mine. The rare earth concentrate produced by integrated membrane concentration is directly extracted with an extractant, without the need to add chemical reagents for precipitation, flocculants, or plate-frame filtration for solid-liquid separation. Acid dissolution is not required before extraction, which greatly shortens the mining, beneficiation and smelting processes of ionic rare earths. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the traditional rare earth mining, beneficiation and smelting process;

[0037] Figure 2 This is a short process diagram of rare earth mining-membrane concentration-smelting in the present invention;

[0038] Figure 3 It is a schematic diagram of the process flow of multi-stage reverse osmosis membrane concentration in the present invention;

[0039] In the figure, 1. nanofiltration membrane stack; 2. primary reverse osmosis membrane stack; 3. secondary reverse osmosis membrane stack; 4. tertiary reverse osmosis membrane stack; 5. quaternary reverse osmosis membrane stack. DETAILED DESCRIPTION

[0040] like Figure 2 As shown, the present invention provides a method for preparing ionic rare earths, specifically: a short-process preparation method for mining, selection and smelting of ionic rare earths, comprising the following steps:

[0041] Step (1), the clear liquid obtained after pre-treatment of the ionic rare earth leaching mother liquid is subjected to separation of monovalent ions and high-valent ions to obtain a permeate and a interception liquid respectively;

[0042] In step (1), preferably, a nanofiltration membrane is used to separate monovalent ions from high-valent ions. Preferably, the operating pressure of the nanofiltration membrane is 0.4-1.2 MPa.

[0043] The monovalent ions are mainly monovalent Na + , Cl - Etc. High-valent ions mainly refer to divalent (M 2+ ) or two or more valences (R 3 + ) rare earth ions. Nanofiltration membranes allow monovalent ions to pass through, but not divalent or higher ions, thus achieving the separation of monovalent and high-valent ions.

[0044] Step (2), the permeate is returned to the leaching agent water distribution tank for use in the preparation of the leaching agent, so as to achieve full reuse of production water; the retentate is subsequently concentrated by a multi-stage reverse osmosis membrane to produce a rare earth concentrate for rare earth extraction.

[0045] Wherein, in step (2), the multi-stage reverse osmosis membrane concentration is determined according to the concentration of rare earth ions in the retentate to ensure that each stage of the reverse osmosis membrane is in the best operating state. In step (2), the multi-stage reverse osmosis membrane concentration is preferably a four-stage reverse osmosis membrane concentration. The four-stage reverse osmosis membrane concentration preferably includes:

[0046] First-stage reverse osmosis membrane concentration: When the rare earth ion concentration is lower than 0.5 g / l, a low-pressure, high-flux reverse osmosis membrane element is used; preferably, the first-stage reverse osmosis membrane concentration operating pressure is 1.0-1.6 MPa.

[0047] Second stage reverse osmosis membrane concentration: When the rare earth ion concentration is concentrated to 1.2 g / l, a medium pressure high rejection rate reverse osmosis membrane is used; preferably, the operating pressure of the second stage reverse osmosis membrane concentration is 1.5-2.5 MPa.

[0048] Third-stage reverse osmosis membrane concentration: When the rare earth ion concentration is concentrated to 2.4 g / l, a high-pressure and high-rejection reverse osmosis membrane is used; preferably, the operating pressure of the third-stage reverse osmosis membrane concentration is 2.0-4.5 MPa.

[0049] Fourth stage reverse osmosis membrane concentration: When the rare earth ion content exceeds 4g / l, a disc-tube ultra-high pressure reverse osmosis membrane is used; preferably, the operating pressure of the fourth stage reverse osmosis membrane concentration is 4.0-7.5MPa.

[0050] Step (3), extracting and stripping the rare earth concentrate in step (2) in sequence to obtain a rare earth concentrate; preferably, in step (3), an extractant is directly added to the rare earth concentrate for separation and purification without adding acid for dissolution. Specifically, it can be:

[0051] The rare earth concentrate in step (2) is transported to a rare earth smelter in liquid form, and an extractant is directly added to the rare earth concentrate for separation and purification without adding acid for dissolution. The membrane concentrate replaces the chemical precipitation, solid-liquid separation and acid dissolution stages, thereby simplifying the process steps of rare earth mining, beneficiation and smelting.

[0052] like Figure 3 As shown, a specific implementation method of separating and concentrating rare earths by integrated membrane technology in the present invention is shown, which can be specifically as follows: the rare earth leaching mother liquor collected by in-situ leaching in the mine is firstly subjected to a gravity impurity removal pretreatment system, and then pumped into a nanofiltration membrane stack 1 by a pump, and the nanofiltration membrane permeate is returned to the leaching agent preparation, and the nanofiltration membrane retentate (rare earth leaching liquid) enters a primary reverse osmosis membrane transfer water tank; the rare earth leaching liquid in the transfer water tank is pumped into a primary reverse osmosis membrane stack 2 by a pump, and the primary reverse osmosis membrane permeate is returned to the leaching agent preparation, and the primary reverse osmosis membrane retentate (primary concentrated rare earth) enters a secondary reverse osmosis membrane transfer water tank; the primary concentrated rare earth in the transfer water tank is pumped into a secondary reverse osmosis membrane stack 3 by a pump, and the secondary reverse osmosis membrane permeate is returned to the primary reverse osmosis membrane transfer water tank, and the rare earth leaching liquid is The secondary concentrated rare earth in the transfer water tank is pumped into the tertiary reverse osmosis membrane stack 4 by a pump, and the tertiary reverse osmosis membrane permeate returns to the secondary reverse osmosis membrane transfer water tank, and circulates into the secondary reverse osmosis membrane stack together with the primary concentrated rare earth, and the tertiary reverse osmosis membrane retentate (tertiary concentrated rare earth) enters the quaternary reverse osmosis membrane transfer water tank; the tertiary concentrated rare earth in the transfer water tank is pumped into the quaternary reverse osmosis membrane stack 5 by a pump, and the quaternary reverse osmosis permeate returns to the tertiary reverse osmosis transfer water tank, and circulates into the tertiary reverse osmosis membrane stack together with the secondary concentrated rare earth, and the quaternary reverse osmosis retentate returns to the quaternary reverse osmosis transfer water tank, and is continuously concentrated to finally obtain quaternary concentrated rare earth.

[0053] Step (4), sending the four-stage concentrated rare earth in step (3) to a rare earth extraction-strip extraction system to purify and obtain ionic rare earth.

[0054] In order to further improve the recovery rate of rare earth, in the present invention, the produced water of the second stage reverse osmosis membrane is returned to the first stage reverse osmosis membrane for concentration;

[0055] The produced water concentrated by the third-stage reverse osmosis membrane is returned to the second-stage reverse osmosis membrane for concentration;

[0056] The produced water concentrated by the fourth stage reverse osmosis membrane is returned to the third stage reverse osmosis membrane for concentration;

[0057] The produced water concentrated by the first stage reverse osmosis membrane is returned to the water pool for the configuration of the leaching agent.

[0058] In the present invention, in step (1), the pretreatment is gravity impurity removal.

[0059] In the present invention, the nanofiltration membrane and the first, second and third stage reverse osmosis membrane elements are spiral membrane components; the fourth stage reverse osmosis is a disc-tube (DTRO) membrane component.

[0060] In the present invention, a transfer water tank is arranged in front of each stage of the reverse osmosis membrane concentration system, and the water from the previous stage is stored in the transfer water tank, and the reverse osmosis produced water of the next stage is returned to the transfer water tank. The transfer water tank is provided with a high-pressure pump, which is responsible for pumping the solution in the transfer water tank into the corresponding membrane treatment system, and the produced water of the first-stage reverse osmosis and nanofiltration membrane is returned to the water for preparing the leaching agent.

[0061] The whole system of the present invention does not need to add chemical precipitants. The water produced by concentrating the permeate is reused for the preparation of leaching agents, and the kerosene in the extraction section will not be brought into the mine, thus avoiding the serious harm to the ecological environment caused by the return of kerosene to the mine. The rare earth concentrate produced by reverse osmosis membrane concentration is directly extracted with an extractant, without the need to add chemical reagents for precipitation, flocculants, or plate-and-frame filtration for solid-liquid separation. No acid dissolution is required before extraction, which greatly shortens the mining, beneficiation and smelting processes of ionic rare earths.

[0062] The technical solution of the present invention is described clearly and in detail below in conjunction with specific embodiments.

[0063] Example 1

[0064] The rare earth concentration of 0.22g / l rare earth leaching mother liquor is 0.30g / l after separation by nanofiltration membrane at 1.2MPa; the rare earth concentration is concentrated to 0.95g / l after concentration by primary reverse osmosis membrane at 1.6MPa; the rare earth concentration is concentrated to 2.36g / l after concentration by secondary reverse osmosis membrane at 1.5MPa; the rare earth concentration is concentrated to 5.24g / l after concentration by tertiary osmosis membrane at 3.5MPa; the rare earth concentration is concentrated to 12.31g / l after concentration by disc-tube ultra-high pressure reverse osmosis membrane at 7.5MPa; the rare earth concentration in the stripping liquid reaches 125g / l after extraction with an extractant, the rare earth concentration in the nanofiltration permeate is less than 0.0025mg / l, the rare earth concentration in the primary reverse osmosis membrane permeate is less than 0.0003mg / l, and the theoretical recovery rate of rare earth reaches 99.3%.

[0065] Example 2

[0066] The rare earth concentration of 0.18g / l rare earth leaching mother liquor is 0.27g / l after separation by nanofiltration membrane at 0.8MPa; after concentration by primary reverse osmosis membrane at 1.0MPa, the rare earth concentration is concentrated to 1.05g / l; after concentration by secondary reverse osmosis at 2.5MPa, the rare earth concentration is concentrated to 2.25g / l; after concentration by tertiary osmosis membrane at 2.0MPa, the rare earth concentration is concentrated to 4.62g / l; after concentration by disc-tube ultra-high pressure reverse osmosis membrane at 4.0MPa, the rare earth concentration is concentrated to 11.05g / l; after extraction with extractant, the rare earth concentration in the stripping liquid reaches 105g / l, the rare earth concentration in the nanofiltration permeate is less than 0.004mg / l, the rare earth concentration in the primary reverse osmosis membrane permeate is less than 0.0001mg / l, and the theoretical recovery rate of rare earth reaches 99.4%.

[0067] Example 3

[0068] The rare earth concentration of 0.12g / l rare earth leaching mother liquor is 0.21g / l after separation by nanofiltration membrane at 0.4MPa; the rare earth concentration is concentrated to 1.14g / l after concentration by primary reverse osmosis membrane at 1.2MPa; the rare earth concentration is concentrated to 2.12g / l after concentration by secondary reverse osmosis membrane at 2.0MPa; the rare earth concentration is concentrated to 4.37g / l after concentration by tertiary osmosis membrane at 4.5MPa; the rare earth concentration is concentrated to 11.09g / l after concentration by disc-tube ultra-high pressure reverse osmosis membrane at 6.0MPa; the rare earth concentration in the stripping liquid reaches 116g / l after extraction with an extractant, the rare earth concentration in the nanofiltration permeate is less than 0.0035mg / l, the rare earth concentration in the primary reverse osmosis membrane permeate is less than 0.0002mg / l, and the theoretical recovery rate of rare earth reaches 99.5%.

[0069] Comparative Example 1

[0070] Use Figure 1 According to the prior art shown in the figure, for a rare earth leaching mother liquor of 0.22 g / l, chemical impurity removal requires the addition of 0.122 g / g of rare earth carbonate, the impurity removal slag requires the consumption of 0.006 g / sulphuric acid, the chemical precipitation requires the addition of 0.752 g / g of rare earth carbonate, the rare earth content in the chemical precipitation supernatant is 0.02 g / l, and 0.008 g / g of rare earth flocculant is required, and the theoretical recovery rate of rare earth is only 84.6%.

[0071] Comparative Example 2

[0072] Use Figure 1According to the prior art shown, 0.18 g / l of rare earth leaching mother liquor requires the addition of 0.098 g / g of rare earth carbonate for chemical impurity removal, 0.005 g / g of sulfuric acid is consumed in the impurity removal slag, 0.615 g / g of rare earth carbonate is added for chemical precipitation, the rare earth content in the chemical precipitation supernatant is 0.03 g / l, 0.007 g / g of rare earth flocculant is consumed, and the theoretical recovery rate of rare earth is 85.4%.

[0073] Comparative Example 3

[0074] Use Figure 1 According to the prior art shown in the figure, for 0.12 g / l rare earth leaching mother liquor, 0.067 g / g rare earth carbonate needs to be added for chemical impurity removal, 0.003 g / g concentrated sulfuric acid needs to be consumed in the impurity removal residue, 0.410 g / g rare earth carbonate needs to be added for chemical precipitation, the rare earth content in the chemical precipitation supernatant is 0.02 g / l, 0.004 g / g rare earth flocculant needs to be consumed, and the theoretical recovery rate of rare earth is 82.7%.

[0075] By comparing Examples 1-3 and Comparative Examples 1-3, the new process does not need to add chemical impurity removers, chemical precipitants, sulfuric acid, and flocculants; it does not need to build chemical precipitation tanks, and does not need plate and frame filtration equipment; the rare earth content in the nanofiltration membrane permeate and the primary reverse osmosis permeate is lower than 0.0003 mg / l, and the lost trace rare earth still returns to the mine in an ionic state through the leaching agent and can be re-leached by the leaching agent; the overall recovery rate of rare earth in the rare earth mother liquor leached once is higher than 99.3%, which is much higher than the theoretical recovery rate of the traditional process. The newly invented process flow is significantly shorter than the traditional process, reduces the consumption of raw materials, cuts down on infrastructure investment, saves manual operation, and greatly improves the recovery rate of rare earth.

Claims

1. A method for preparing ionic rare earth, characterized in that: The steps include: Step (1), the clear liquid obtained after pre-treatment of the ionic rare earth leaching mother liquid is subjected to separation of monovalent ions and high-valent ions to obtain a permeate and a interception liquid respectively; Step (2), the permeate is returned to the leaching agent water distribution tank for use in the preparation of the leaching agent, so as to achieve full reuse of the production water; the retentate is subsequently concentrated by a multi-stage reverse osmosis membrane to obtain a rare earth concentrate, which is directly subjected to rare earth extraction; Step (3), extracting and stripping the rare earth concentrate in step (2) in sequence to obtain a rare earth concentrate; Step (4), refining the rare earth concentrate in step (3) to obtain ionic rare earth.

2. The method for preparing an ionic rare earth according to claim 1, characterized in that: In step (2), the multi-stage reverse osmosis membrane concentration is determined according to the concentration of rare earth ions in the retentate.

3. The method for preparing an ionic rare earth according to claim 2, characterized in that: In step (2), the multi-stage reverse osmosis membrane concentration is four-stage reverse osmosis membrane concentration.

4. The method for preparing an ionic rare earth according to claim 3, characterized in that: Four-stage reverse osmosis membrane concentration includes: First-stage reverse osmosis membrane concentration: When the rare earth ion concentration is lower than 0.5g / l, a low-pressure, high-flux reverse osmosis membrane element is used; Second stage reverse osmosis membrane concentration: When the rare earth ion concentration is concentrated to 1.2g / l, a medium pressure high rejection rate reverse osmosis membrane is used; The third stage reverse osmosis membrane concentration: when the rare earth ion concentration is concentrated to 2.4g / l, a high pressure and high retention rate reverse osmosis membrane is used; Fourth-stage reverse osmosis membrane concentration: When the rare earth ion content exceeds 4g / l, a disc-tube ultra-high pressure reverse osmosis membrane is used.

5. The method for preparing an ionic rare earth according to claim 4, characterized in that: The first-stage reverse osmosis membrane concentration operating pressure is 1.0-1.6MPa; The operating pressure of the second-stage reverse osmosis membrane concentration is 1.5-2.5MPa; The operating pressure of the third-stage reverse osmosis membrane concentration is 2.0-4.5MPa; The operating pressure of the fourth stage reverse osmosis membrane concentration is 4.0-7.5MPa.

6. The method for preparing an ionic rare earth according to claim 5, characterized in that: The produced water concentrated by the second stage reverse osmosis membrane is returned to the first stage reverse osmosis membrane for concentration; The produced water concentrated by the third-stage reverse osmosis membrane is returned to the second-stage reverse osmosis membrane for concentration; The produced water concentrated by the fourth stage reverse osmosis membrane is returned to the third stage reverse osmosis membrane for concentration; The produced water concentrated by the first stage reverse osmosis membrane is returned to the water pool for preparing the leaching agent.

7. The method for preparing an ionic rare earth according to claim 1, characterized in that: In step (1), a nanofiltration membrane is used to separate monovalent ions and high-valent ions.

8. The method for preparing an ionic rare earth according to claim 7, characterized in that: The operating pressure of the nanofiltration membrane is 0.4-1.2MPa.

9. The method for preparing an ionic rare earth according to claim 1, characterized in that: In step (3), the extractant is directly added to the rare earth concentrate for separation and purification without adding acid for dissolution.

10. A method for preparing ionic rare earth according to any one of claims 1 to 9, characterized in that: In step (1), the pretreatment is gravity impurity removal.

Images