Method and device for preparing rare earth oxalate from low-concentration rare earth feed liquid

Abstract

The invention provides a method and device for preparing rare earth oxalate from low-concentration rare earth feed liquid, and belongs to the technical field of rare earth recovery. The method comprises the following steps: adsorbing the low-concentration rare earth feed liquid by adopting cation exchange resin to obtain loaded resin; in terms of rare earth oxides, the concentration of the rare earth elements in the low-concentration rare earth feed liquid does not exceed 1g / L; the cation exchange resin comprises ammonium type cation exchange resin, sodium type cation exchange resin, potassium type cation exchange resin or magnesium type cation exchange resin; and desorbing the loaded resin column by using an oxalic acid aqueous solution as a desorption agent to obtain the rare earth oxalate. According to the method, reagent consumption is reduced, enrichment of rare earth in the low-concentration rare earth feed liquid can be effectively achieved, the recovery rate and purity of the rare earth are improved, the recovery rate of the rare earth reaches 97% or above, and the purity of the rare earth reaches 99.9% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth recovery, and in particular relates to a method and a device for preparing rare earth oxalate by using a low-concentration rare earth liquid. Background Art

[0002] With the rapid development of China's modern industry, the over-exploitation of rare earth resources has led to a gradual reduction in its reserves, and the resource situation is becoming increasingly severe. As a non-renewable resource, the recovery of rare earths from low-concentration rare earth wastewater is not only economically beneficial, but also of great environmental significance.

[0003] The sources of low-concentration rare earth wastewater are very wide, for example: low-concentration rare earth solution produced in the process of rare earth ore extraction, wastewater containing rare earth elements produced in industrial production processes such as metallurgy, electronics, and catalysts, and rare earth elements coexisting in non-rare earth ores such as tantalum-niobium ore, bauxite, and phosphate. The rare earth concentration in the above-mentioned low-concentration rare earth wastewater is low, and generally contains Al 3+ , Fe 3+ Plasma impurities, these impurities will interfere with the separation and recovery of rare earth elements, increasing the difficulty of recovery.

[0004] At present, there are various methods for recovering and enriching low-concentration rare earths, among which precipitation and ion exchange are the most widely used. However, the precipitation method has low selectivity for impurity ions, which will reduce the rare earth precipitation rate and the purity of rare earth products. A large amount of impurities are easy to form complex salts with rare earths to reduce the rare earth precipitation rate, and more precipitants are required. Especially when the rare earth concentration is lower than 1g / L, the recovery rate of rare earths recovered by precipitation is as low as 30-60%, and it is necessary to double the consumption of precipitants such as sodium carbonate and oxalic acid. The ion exchange method consumes a lot of water and consumes a lot of desorbents. At the same time, when using precipitation or ion exchange for rare earth recovery, Al 3+ , Fe 3+ A large amount of plasma impurities enter the recycled rare earth products, and the purity of the resulting rare earth products is low, often failing to meet national standards. Summary of the invention

[0005] The purpose of the present invention is to provide a method and device for preparing rare earth oxalate using low-concentration rare earth liquid. The method provided by the present invention reduces reagent consumption, can effectively achieve the enrichment of rare earth in low-concentration rare earth liquid, and obtain Al in one step. 3+ , Fe 3+ The plasma impurity content of the rare earth oxalate product is low and meets the national standards. The device is movable and the water resources in the system can be recycled, which improves the recovery rate and purity of the rare earth and improves the overall efficiency.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing rare earth oxalate by using a low-concentration rare earth solution, wherein the rare earth element is calculated as rare earth oxide, and the concentration of the rare earth element in the low-concentration rare earth solution does not exceed 1 g / L, comprising the following steps:

[0008] Adsorbing the low-concentration rare earth solution with a cation exchange resin to obtain a loaded resin; the cation exchange resin includes an ammonium cation exchange resin, a sodium cation exchange resin, a potassium cation exchange resin or a magnesium cation exchange resin;

[0009] The loaded resin column is desorbed by using an oxalic acid aqueous solution as a desorbent to obtain rare earth oxalate.

[0010] Preferably, the concentration of the rare earth element in the low-concentration rare earth solution is 0.09-0.2 g / L.

[0011] Preferably, the low-concentration rare earth solution further includes iron ions, and the concentration of the iron ions is 0.26-0.54 mg / L.

[0012] Preferably, the low-concentration rare earth solution further comprises aluminum ions, and the concentration of the aluminum ions is 20.2 to 140 mg / L.

[0013] Preferably, the particle size of the cation exchange resin is 0.3-1.2 mm.

[0014] Preferably, the cation exchange resin is obtained by transforming a blank resin; the blank resin includes TP207, D463, S400 or D155.

[0015] Preferably, the concentration of the oxalic acid aqueous solution is 40-80 g / L; the dosage ratio of the loaded resin to the oxalic acid aqueous solution is 100 g: 210-410 mL.

[0016] Preferably, after the desorption, the method further includes: subjecting the obtained feed liquid to filter membrane separation, and collecting the solid-liquid mixture passing through the filter membrane; subjecting the solid-liquid mixture to solid-liquid separation, and collecting solid material; the solid material is the rare earth oxalate; the pore size of the filter membrane used for the filter membrane separation is smaller than the particle size of the cation exchange resin.

[0017] The present invention provides a device for preparing rare earth oxalate by using low-concentration rare earth liquid, comprising a first liquid storage container, a second liquid storage container and an ion exchange column; the first liquid storage container is used to store the low-concentration rare earth liquid, the second liquid storage container is used to store oxalic acid aqueous solution, the ion exchange column comprises a column body and a cation exchange resin inside the column body; the discharge ports of the first liquid storage container and the second liquid storage container are connected to the feed port of the ion exchange column.

[0018] Preferably, the device for preparing rare earth oxalate using low-concentration rare earth liquid also includes a filter membrane, a stirring paddle and a solid-liquid separation device; the filter membrane is arranged at the bottom of an ion exchange column; the pore size of the filter membrane is smaller than the particle size of a cation exchange resin; the stirring paddle is arranged inside the ion exchange column and does not contact the filter membrane; the solid-liquid separation device is arranged outside the ion exchange column.

[0019] The present invention provides a method for preparing rare earth oxalate using a low-concentration rare earth feed solution, wherein the rare earth element is calculated as rare earth oxide, and the concentration of the rare earth element in the low-concentration rare earth feed solution does not exceed 1g / L, and comprises the following steps: using a cation exchange resin to adsorb the low-concentration rare earth feed solution to obtain a loaded resin; the cation exchange resin includes an ammonium-type cation exchange resin, a sodium-type cation exchange resin, a potassium-type cation exchange resin or a magnesium-type cation exchange resin; using an oxalic acid aqueous solution as a desorbent to desorb the loaded resin column to obtain a rare earth oxalate. In the present invention, an ion exchange reaction occurs between the rare earth ions and the functional groups on the cation exchange resin, which significantly increases the concentration of the rare earth; on this basis, the present invention uses an oxalic acid aqueous solution for one-step desorption, and the oxalic acid aqueous solution can not only play the role of a desorbent, but also has the functions of a desorbent and a precipitant, and the rare earth ions react with oxalate ions under acidic conditions to form a rare earth oxalic acid precipitate, and impurities such as iron and aluminum are dissolved in the solution, thereby achieving efficient separation of rare earths. The method provided by the present invention reduces the reagent consumption, can effectively realize the enrichment of rare earth in low-concentration rare earth liquid, and improves the recovery rate and purity of rare earth. In the embodiment, the recovery rate of rare earth reaches more than 97%; the purity of rare earth reaches more than 99.9% in terms of rare earth oxide (REO); at the same time, in the rare earth oxalate obtained by the method provided by the present invention, Al 3+ , Fe 3+ The plasma impurity content is low. The Al2O3 content in the rare earth oxalate obtained in the embodiment is only 0.19wt%, and the Fe2O3 content is only 46ppm, which meets the national standard (GB / T20169-2015 Ionic rare earth ore mixed rare earth oxides).

[0020] The present invention provides a device for preparing rare earth oxalate with low-concentration rare earth liquid, comprising a first liquid storage container, a second liquid storage container and an ion exchange column; the first liquid storage container is used to store the low-concentration rare earth liquid, the second liquid storage container is used to store the oxalic acid aqueous solution, and the ion exchange column comprises a column body and a cation exchange resin inside the column body; the discharge ports of the first liquid storage container and the second liquid storage container are connected to the feed port of the ion exchange column. The device of the present invention is used to enrich rare earths in low-concentration rare earth liquid, and the three steps of resin desorption, impurity removal and rare earth precipitation can be integrated into one process, which greatly simplifies the process flow, saves production costs, and improves overall efficiency.

[0021] Further, the device for preparing rare earth oxalate with low-concentration rare earth liquid according to the present invention is also provided with a filter membrane, a stirring paddle and a solid-liquid separation device. After desorption is completed, the present invention separates the blank resin obtained by desorption and the rare earth oxalate precipitate through the stirring action of the stirring paddle. The blank resin cannot pass through the filter membrane, and the rare earth oxalate precipitate can enter the solid-liquid separation device through the filter membrane, thereby obtaining high-purity rare earth oxalate and blank resin respectively; the blank resin can be transformed and re-prepared into a cation exchange resin, and then returned to the above-mentioned ion exchange system for reuse, and the water resources in the system can be recycled, which effectively realizes resource conservation and is environmentally friendly. Moreover, the device for preparing rare earth oxalate with low-concentration rare earth liquid provided by the present invention can be flexibly moved, and the whole set of equipment for preparing rare earth oxalate can be flexibly disassembled and assembled, and can be relocated to different regions for rare earth recovery according to demand, thereby maximizing the use of equipment and optimizing the return on investment of fixed assets; the flexibility of the device not only improves the utilization rate of equipment, but also enhances the adaptability of enterprises to changes in market demand and improves market competitiveness.

[0022] In summary, the present invention provides a method and device integrating enrichment, desorption and separation, which not only improves the recovery rate and product purity of rare earths, but also helps to achieve sustainable utilization of rare earth resources and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 The process flow chart of preparing rare earth oxalate using low concentration rare earth liquid;

[0025] Figure 2 The schematic diagram of the device for preparing rare earth oxalate using low-concentration rare earth liquid is shown in the figure, wherein: 1-column; 2-cation exchange resin; 3-stirring paddle; 4-filter membrane. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing rare earth oxalate by using a low-concentration rare earth solution, wherein the rare earth element is calculated as rare earth oxide, and the concentration of the rare earth element in the low-concentration rare earth solution does not exceed 1 g / L, comprising the following steps:

[0027] Adsorbing the low-concentration rare earth solution with a cation exchange resin to obtain a loaded resin; the cation exchange resin includes an ammonium cation exchange resin, a sodium cation exchange resin, a potassium cation exchange resin or a magnesium cation exchange resin;

[0028] The loaded resin column is desorbed by using an oxalic acid aqueous solution as a desorbent to obtain rare earth oxalate.

[0029] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared by methods well known to those skilled in the art.

[0030] In the present invention, the rare earth elements are calculated as rare earth oxides, and the concentration of rare earth elements in the low-concentration rare earth solution does not exceed 1g / L, specifically 0.09-0.2g / L; in a specific embodiment, the concentration of rare earth elements in the low-concentration rare earth solution can be 0.09g / L, 0.13g / L or 0.2g / L. In the present invention, the low-concentration rare earth solution can also include iron ions, and the concentration of the iron ions can be 0.26-0.54mg / L; in a specific embodiment, the concentration of the iron ions in the low-concentration rare earth solution can be 0.26mg / L, 0.32mg / L or 0.54mg / L. In the present invention, the low-concentration rare earth solution can also include aluminum ions, and the concentration of the aluminum ions can be 20.2-140mg / L; in a specific embodiment, the concentration of the aluminum ions in the low-concentration rare earth solution can be 0.07g / L, 0.14g / L or 20.2mg / L. In one embodiment of the present invention, the low concentration rare earth liquid is C (REO) =0.2g / L, C (总Fe) =0.54mg / L, C (Al3+) =20.2 mg / L of mine leaching mother liquor; In another embodiment of the present invention, the low concentration rare earth feed liquid is C (REO) =0.09g / L, C (总Fe) =0.26mg / L, C (Al3+) =0.07g / L of mine leaching mother liquor; In another embodiment of the present invention, the low concentration rare earth feed liquid is C (REO) =0.13g / L, C (总Fe) =0.32mg / L, C (Al3+) =0.14g / L of rare earth separation plant tail water.

[0031] In the present invention, the cation exchange resin includes ammonium cation exchange resin, sodium cation exchange resin, potassium cation exchange resin or magnesium cation exchange resin; in a specific embodiment, the cation exchange resin is ammonium cation exchange resin or sodium cation exchange resin. In the present invention, the particle size of the cation exchange resin can be 0.3 to 1.2 mm.

[0032] In the present invention, the cation exchange resin can be obtained by transformation of blank resin. In a specific embodiment of the present invention, the preparation method of the cation exchange resin can include the following steps: mixing the blank resin with saline, performing an expansion treatment, and obtaining an expanded resin; mixing the expanded resin with an acid solution, performing an acid treatment, and obtaining a hydrogen-type resin; mixing the hydrogen-type resin with a transformation agent, performing a transformation treatment, and obtaining a cation exchange resin. In an embodiment of the present invention, the blank resin can be TP207, D463, S400, or D155. In a specific embodiment of the present invention, the mass fraction of the saline can be 10%; the volume ratio of the blank resin to the saline can be 1:2; and the time of the expansion treatment is ≥20h. In a specific embodiment of the present invention, the acid solution can be hydrochloric acid; the mass fraction of the hydrochloric acid can be 2-5%, specifically 2%, 3%, 4% or 5%; the volume ratio of the expanded resin to the acid solution can be 1:2; and the time of the acid treatment is ≥4h. In the present invention, the transformation agent can be ammonia water, sodium hydroxide solution, potassium hydroxide solution, or magnesium hydroxide solution. In a specific embodiment of the present invention, the transformation agent can be ammonia water; the mass fraction of ammonia water can be 5%; the volume ratio of the hydrogen resin to the transformation agent can be 1:2; the time of the transformation treatment is ≥ 4h. In a specific embodiment of the present invention, the expansion treatment, acid treatment and transformation treatment can be washed with water respectively.

[0033] After obtaining the cation exchange resin, the present invention packs the cation exchange resin into a column to obtain a cation exchange resin column. In a specific embodiment of the present invention, the diameter of the cation exchange resin column can be 100 mm and the height can be 1000 mm; the packing height of the cation exchange resin in the cation exchange resin column can be 600 mm.

[0034] After obtaining the cation exchange resin column, the present invention loads the low-concentration rare earth feed liquid onto the cation exchange resin column for adsorption to obtain a loaded resin column. In a specific embodiment of the present invention, the adsorption is stopped when the adsorption reaches adsorption equilibrium (when the concentration of rare earth oxide (REO) in the adsorbed liquid and the adsorption mother liquor is equal, it is considered to be adsorption equilibrium). In a specific embodiment of the present invention, an adsorbed liquid can also be obtained after the adsorption is completed. In a specific embodiment of the present invention, the adsorbed liquid can be separated by filtering. When the low-concentration rare earth feed liquid is a mine leaching mother liquor, the adsorbed liquid can be used to prepare a leaching agent and returned to the leaching system for leaching.

[0035] After obtaining the loaded resin column, the present invention uses an oxalic acid aqueous solution as a desorbent to desorb the loaded resin column to obtain rare earth oxalate. In the present invention, the concentration of the oxalic acid aqueous solution can be 40 to 80 g / L; in a specific embodiment, the concentration of the oxalic acid aqueous solution can be 40 g / L, 60 g / L or 80 g / L. In the present invention, the dosage ratio of the loaded resin to the oxalic acid aqueous solution can be 100 g: 210 to 410 mL. In a specific embodiment of the present invention, after the desorption, the process also includes subjecting the obtained feed liquid to membrane separation, collecting the solid-liquid mixture passing through the membrane; subjecting the solid-liquid mixture to solid-liquid separation, collecting solid materials, and the solid materials are the rare earth oxalate; the pore size of the membrane used for the membrane separation is smaller than the particle size of the cation exchange resin. In a specific embodiment of the present invention, after the desorption is completed, the obtained feed liquid is subjected to membrane separation, and the first solid material that does not pass through the membrane and the solid-liquid mixture that passes through the membrane are collected respectively; the solid-liquid mixture is subjected to solid-liquid separation to obtain a second solid material and a liquid material; the first solid material is a blank resin; the second solid material is a rare earth oxalate, and the liquid material is a desorption tail liquid. In a specific embodiment of the present invention, the membrane separation is performed under stirring conditions.

[0036] The process principle involved in the method for preparing rare earth oxalate using low-concentration rare earth liquid according to the present invention is as follows:

[0037] (1) Resin transformation (using ammonia as a transformation agent as an example):

[0038]

[0039] (2) Adsorption reaction:

[0040] (Me n+ =RE 3+ 、Al 3+ , Fe 3+ Plasma

[0041] (3) One-step reaction principle of loaded resin desorption, impurity removal and precipitation:

[0042]

[0043] The present invention firstly uses a cation exchange resin to adsorb rare earth ions in a low-concentration rare earth feed solution, thereby significantly increasing the concentration of rare earth; at the same time, the cation exchange resin can also effectively adsorb impurities such as iron and aluminum, thereby obtaining a loaded resin loaded with rare earth and impurities. On this basis, the present invention uses an oxalic acid aqueous solution for desorption, during which a large amount of iron and aluminum enter the solution, and rare earth ions and oxalate ions form rare earth oxalate precipitation in an acidic environment provided by the oxalic acid solution. Under the action of stirring, the rare earth oxalate precipitation is separated from the resin, and then the rare earth oxalate precipitation passes through a filter membrane, thereby obtaining high-purity rare earth oxalate and blank resin, and the blank resin can be recycled.

[0044] Moreover, the whole system of the present invention realizes the recycling of water resources. The adsorbed liquid obtained after the oxalic acid aqueous solution desorbs the loaded resin can be used to prepare the leaching agent, and the desorbed tail liquid can be used to prepare the transformation agent. Moreover, while the oxalic acid aqueous solution desorbs the resin loaded with rare earth, impurities can be removed and rare earth precipitated, which saves chemical reagents, simplifies the operation process, and reduces production costs.

[0045] The present invention provides a device for preparing rare earth oxalate by using low-concentration rare earth liquid, comprising a first liquid storage container, a second liquid storage container and an ion exchange column; the first liquid storage container is used to store the low-concentration rare earth liquid, the second liquid storage container is used to store oxalic acid aqueous solution, the ion exchange column comprises a column body and a cation exchange resin inside the column body; the discharge ports of the first liquid storage container and the second liquid storage container are connected to the feed port of the ion exchange column.

[0046] In one embodiment of the present invention, the device for preparing rare earth oxalate using low-concentration rare earth liquid also includes a filter membrane, a stirring paddle and a solid-liquid separation device; the filter membrane is arranged at the bottom of an ion exchange column; the pore size of the filter membrane is smaller than the particle size of a cation exchange resin; the stirring paddle is arranged inside the ion exchange column and does not contact the filter membrane; the solid-liquid separation device is arranged outside the ion exchange column.

[0047] The device for preparing rare earth oxalate with low-concentration rare earth liquid described in the present invention has achieved an important breakthrough in rare earth separation and enrichment technology. Through the application of cation exchange resin and oxalic acid aqueous solution, not only the efficiency of rare earth separation and enrichment is improved, but the device can also be flexibly moved and can be relocated to different regions for rare earth recovery according to demand, which can maximize the utilization of equipment and reduce production costs, thus contributing to the efficient utilization of rare earth resources and environmental protection.

[0048] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The blank resin used in the examples is German LANXESS TP207 resin, produced by Shenzhen Hengda Xingye Environmental Protection Technology Co., Ltd.;

[0050] The device used in the embodiment for preparing rare earth oxalate with low-concentration rare earth liquid comprises a first liquid storage container, a second liquid storage container, an ion exchange column, a filter membrane, a stirring paddle and a solid-liquid separation device; the first liquid storage container is used to store low-concentration rare earth liquid, the second liquid storage container is used to store oxalic acid aqueous solution, the ion exchange column comprises a column body and a cation exchange resin inside the column body; the discharge ports of the first liquid storage container and the second liquid storage container are connected to the feed port of the ion exchange column; the filter membrane is arranged at the bottom of the ion exchange column; the pore size of the filter membrane is smaller than the particle size of the cation exchange resin; the stirring paddle is arranged inside the ion exchange column and does not contact the filter membrane; the stirring paddle comprises a stirring shaft and a blade arranged on the stirring shaft; the blade is at least two layers, and each layer of the blade is provided with at least two blades; the solid-liquid separation device is arranged outside the ion exchange column. A schematic diagram of the device for preparing rare earth oxalate with low-concentration rare earth liquid is shown in FIG. Figure 2 As shown, 1 is a column; 2 is a cation exchange resin; 3 is a stirring paddle; and 4 is a filter membrane.

[0051] Preparation Example 1

[0052] Soak a blank resin (pore size of 0.3-1.2 mm) in 10wt% saline solution, which is twice the volume of the resin, for 20 hours to obtain an expanded resin. Then wash the expanded resin with clean water until the washing liquid is no longer yellow. Then soak the washed expanded resin in 2wt% hydrochloric acid (mass fraction of 2%), which is twice the volume of the expanded resin, for 4 hours to obtain a hydrogen-type resin. Then wash the hydrogen-type resin with clean water until the washing liquid is neutral. Then soak the washed hydrogen-type resin in 5wt% ammonia water, which is twice the volume of the hydrogen-type resin, for 4 hours, and then wash the resin with clean water until the washing liquid is neutral. At this time, the resin is NH4 + Type cation exchange resin.

[0053] The NH4 + Cation exchange resin column The column height is 600 mm, and the NH4 + Ion exchange column of type cation exchange resin.

[0054] Preparation Example 2

[0055] The conversion agent in Preparation Example 1 was replaced by sodium hydroxide from ammonia water, and the other conditions were the same as those in Preparation Example 1 to prepare Na + Type cation exchange resin.

[0056] The Na + Type cation exchange resin loaded into resin column The column height is 600 mm, and the column is loaded with Na + Ion exchange column of type cation exchange resin.

[0057] Example 1

[0058] Select C (REO) =0.2g / L, C (总Fe) =0.54mg / L, C (Al3+) = 20.2 mg / L of the mine leaching mother liquor, filter the sediment and suspended matter with a sand filter, and load the obtained filtrate on the Na + The ion exchange column of the type cation exchange resin is subjected to dynamic adsorption until adsorption equilibrium is reached (when the REO concentrations in the adsorbed liquid and the adsorbed mother liquid are equal, it is considered as adsorption equilibrium), to obtain loaded resin (loaded with rare earth elements) and adsorbed liquid, and the adsorbed liquid is taken out (which can be used to prepare a leaching agent).

[0059] Stirring was started, and 0.69L of 80g / L oxalic acid aqueous solution was added to the ion exchange column to desorb the loaded resin. As desorption proceeded, the loaded resin in the ion exchange column gradually became blank resin, and a precipitate was gradually generated in the system. Under stirring, the precipitate was separated from the blank resin, and passed through a filter membrane together with the remaining liquid material in the system (the pore size of the filter membrane was smaller than that of the blank resin, and the blank resin continued to stay in the column and could be reused) to obtain a solid-liquid mixture. The solid-liquid mixture was subjected to solid-liquid separation, and solid materials and liquid materials were collected separately. The liquid material was a desorption tail liquid (which could be used to prepare a transformation agent). The solid material was washed and then tested using a gravimetric method. The results are shown in Table 1.

[0060] Table 1 Test results of solid materials obtained in Example 1

[0061]

[0062] As shown in Table 1, the solid material obtained in Example 1 is rare earth oxalate. The method provided by the present invention can effectively separate and enrich rare earths in low-concentration rare earth liquid, thereby improving the recovery rate and purity of rare earths. 3+ , Fe 3+The plasma impurity content is low and meets the national standard (GB / T20169-2015 Ionic rare earth ore mixed rare earth oxides).

[0063] Example 2

[0064] Select C (REO) =0.09g / L, C (总Fe) =0.26mg / L, C (Al3+) = 0.07 g / L of the mine leaching mother liquor, filter the silt and suspended matter with a sand filter, and load the obtained filtrate on the NH4 + The ion exchange column of the type cation exchange resin is subjected to dynamic adsorption until adsorption equilibrium is reached (when the REO concentrations in the adsorbed liquid and the adsorbed mother liquid are equal, it is considered as adsorption equilibrium), to obtain loaded resin (loaded with rare earth elements) and adsorbed liquid, and the adsorbed liquid is taken out (which can be used to prepare a leaching agent).

[0065] Stirring was started, and 1L of oxalic acid aqueous solution with a concentration of 60g / L was added to the ion exchange column to desorb the loaded resin. As desorption proceeds, the loaded resin in the ion exchange column gradually becomes blank resin, and a precipitate is gradually generated in the system. Under stirring, the precipitate is separated from the blank resin, and passes through a filter membrane together with the remaining liquid material in the system (the pore size of the filter membrane is smaller than the pore size of the blank resin, and the blank resin continues to stay in the column and can be reused) to obtain a solid-liquid mixture. The solid-liquid mixture was subjected to solid-liquid separation, and solid materials and liquid materials were collected respectively. The liquid material was a desorption tail liquid (which can be used to prepare a transformation agent). The solid material was washed and then detected using a gravimetric method. The results are shown in Table 2.

[0066] Table 2 Test results of solid materials obtained in Example 2

[0067]

[0068] As shown in Table 2, the solid material obtained in Example 2 is rare earth oxalate. The method provided by the present invention can effectively separate and enrich rare earths in low-concentration rare earth liquid, thereby improving the recovery rate and purity of rare earths. 3+ , Fe 3+ The plasma impurity content is low and meets the national standard (GB / T20169-2015 Ionic rare earth ore mixed rare earth oxides).

[0069] Example 3

[0070] Select C (REO) =0.13g / L, C (总Fe) =0.32mg / L, C (Al3+)= 0.14 g / L of rare earth separation plant tail water, adjust the pH value to 4 with ammonia water, and load the obtained pretreated rare earth separation plant tail water on the NH4 + An ion exchange column of a type cation exchange resin is used to perform dynamic adsorption until adsorption equilibrium is reached (when the REO concentrations in the adsorbed liquid and the adsorbed mother liquid are equal, it is considered as adsorption equilibrium), to obtain a loaded resin (loaded with rare earth elements) and an adsorbed liquid, and the adsorbed liquid is taken out.

[0071] Stirring was started, and 1.35L of oxalic acid aqueous solution with a concentration of 40g / L was added to the ion exchange column to desorb the loaded resin. As desorption proceeds, the loaded resin in the ion exchange column gradually becomes blank resin, and a precipitate is gradually generated in the system. Under stirring, the precipitate is separated from the blank resin, and passes through a filter membrane (the pore size of the filter membrane is smaller than that of the blank resin, and the blank resin continues to stay in the column and can be reused) together with the remaining liquid material in the system to obtain a solid-liquid mixture. The solid-liquid mixture was subjected to solid-liquid separation, and solid materials and liquid materials were collected respectively, and the liquid material was a desorption tail liquid (which can be used to prepare a transformation agent). The solid material was washed, and then detected using a gravimetric method, and the results were as shown in Table 3.

[0072] Table 3 Test results of solid materials obtained in Example 1

[0073]

[0074] As shown in Table 3, the solid material obtained in Example 3 is rare earth oxalate. The method provided by the present invention can effectively separate and enrich rare earths in low-concentration rare earth liquid, thereby improving the recovery rate and purity of rare earths. 3+ , Fe 3+ The plasma impurity content is low and meets the national standard (GB / T20169-2015 Ionic rare earth ore mixed rare earth oxides).

[0075] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing rare earth oxalate using a low-concentration rare earth solution, wherein the rare earth element is calculated as rare earth oxide, and the concentration of the rare earth element in the low-concentration rare earth solution does not exceed 1g / L, characterized in that: The following steps are involved: Adsorbing the low-concentration rare earth solution with a cation exchange resin to obtain a loaded resin; the cation exchange resin includes an ammonium cation exchange resin, a sodium cation exchange resin, a potassium cation exchange resin or a magnesium cation exchange resin; The loaded resin is desorbed with an oxalic acid aqueous solution to obtain rare earth oxalate.

2. The method according to claim 1, characterized in that The concentration of the rare earth element in the low-concentration rare earth solution is 0.09-0.2 g / L.

3. The method according to claim 1, characterized in that The low-concentration rare earth solution also includes iron ions, and the concentration of the iron ions is 0.26-0.54 mg / L.

4. The method according to claim 1 or 3, characterized in that: The low-concentration rare earth solution also includes aluminum ions, and the concentration of the aluminum ions is 20.2-140 mg / L.

5. The method according to claim 1, characterized in that The particle size of the cation exchange resin is 0.3-1.2 mm.

6. The method according to claim 1, characterized in that The cation exchange resin is obtained by transformation of blank resin; the blank resin includes TP207, D463, S400 or D155.

7. The method according to claim 1, characterized in that The concentration of the oxalic acid aqueous solution is 40-80 g / L; the dosage ratio of the loaded resin to the oxalic acid aqueous solution is 100 g: 210-410 mL.

8. The method according to claim 1, characterized in that After the desorption, the method further includes: subjecting the obtained feed liquid to filter membrane separation, and collecting the solid-liquid mixture passing through the filter membrane; subjecting the solid-liquid mixture to solid-liquid separation, and collecting solid material, wherein the solid material is the rare earth oxalate; and the pore size of the filter membrane used for the filter membrane separation is smaller than the particle size of the cation exchange resin.

9. A device for preparing rare earth oxalate using a low-concentration rare earth liquid, characterized in that: It includes a first liquid storage container, a second liquid storage container and an ion exchange column; the first liquid storage container is used to store low-concentration rare earth liquid, the second liquid storage container is used to store oxalic acid aqueous solution, and the ion exchange column includes a column body and a cation exchange resin inside the column body; the discharge ports of the first liquid storage container and the second liquid storage container are connected to the feed port of the ion exchange column.

10. The device according to claim 9, characterized in that It also includes a filter membrane, a stirring paddle and a solid-liquid separation device; the filter membrane is arranged at the bottom of the ion exchange column; the pore size of the filter membrane is smaller than the particle size of the cation exchange resin; the stirring paddle is arranged inside the ion exchange column and does not contact the filter membrane; the solid-liquid separation device is arranged outside the ion exchange column.

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