Multi-stage gradient magnetic field device for ultra-long liquid chromatography separation and auxiliary separation method of multi-stage gradient magnetic field device

Abstract

The invention discloses a multistage gradient magnetic field device for ultra-long liquid chromatography separation and an auxiliary separation method thereof, and relates to the technical field of separation, and the multistage gradient magnetic field device comprises a chromatography separation system and a magnetic field auxiliary system; the chromatographic separation system comprises a pulse sample introduction device, a first peristaltic pump, a chromatographic column, a second peristaltic pump, a sample introduction and discharge controller and a pulse sample discharge device which are arranged in sequence; and the magnetic field auxiliary system comprises a strong magnetic ring which is sleeved on the chromatographic column. The invention successfully constructs a set of dynamic separation analysis system for realizing space-time precise control-multistage magnetic field gradient enhanced separation effect by pulse sample introduction. According to the system, the movement of ions in a chromatographic system can be accurately intervened by introducing an external magnetic field, so that target ions are effectively separated from a large number of impurity ions under a non-equilibrium state condition, and high-efficiency analysis is realized.

Description

Technical Field

[0001] The present invention relates to the field of separation technology, in particular to a multi-stage gradient magnetic field device for ultra-long liquid chromatography separation and an auxiliary separation method thereof. Background Art

[0002] Chromatography is both an analytical method and a separation means. The main types of chromatography currently include: reverse phase chromatography (RP), ion exchange chromatography, affinity chromatography, size exclusion chromatography, and ultra-high performance liquid chromatography (UHPLC). The conventional length of most chromatographs is 50-300mm. Long columns (250-300mm) are used for complex sample separation, and short columns (50-150mm) are used for rapid analysis. Although the column length will increase the analysis time, it can effectively improve the resolution. The particle size range of the filler is 1.7-10μm (1.7-2.6μm is commonly used in ultra-high performance systems, and 3-5μm is mostly used in traditional HPLC). Among them, reducing the particle size can improve the column efficiency (increase the number of theoretical plates), but the system pressure increases in a square relationship.

[0003] The core principle of chromatography is based on the differences in the interaction between the mobile phase and the stationary phase, and separation is achieved through the differences in the retention time of different components in the stationary phase. Its separation efficiency is affected by the following factors:

[0004] Stationary phase characteristics: including filler chemical composition (such as silica gel), surface modification (ion exchange groups, affinity ligands) and pore structure.

[0005] Mobile phase dynamics: flow rate control, solvent polarity gradient changes, and temperature regulation.

[0006] Based on existing technology, chromatographic analysis has the following problems and shortcomings:

[0007] (1) The separation and analysis speed has encountered a bottleneck. At present, the improvement of chromatographic separation and analysis speed has encountered significant obstacles and has reached a development bottleneck stage. The single analysis cycle of traditional high-performance liquid chromatography (HPLC) is usually as long as 30-60 minutes; even if ultra-high-performance liquid chromatography (UHPLC) can significantly shorten the time to 5-15 minutes, the equipment cost will soar by 3-5 times, resulting in a significant reduction in cost-effectiveness, making it difficult to meet the growing demand for efficient analysis.

[0008] (2) The problem of column efficiency attenuation. The column efficiency of a chromatographic column is affected by a variety of factors both inside and outside the column. In order to achieve the best performance of the chromatographic column, it is necessary not only to reduce the dead volume outside the column as much as possible, but also to construct a reasonable column structure to minimize the dead volume outside the packed bed, and to adopt sophisticated filling technology. However, the chemical stability of some stationary phases has limitations. For example, the service life of an ion exchange column usually does not exceed 500 injections. Under high temperature or extreme pH conditions, the degradation rate of the filler will accelerate, seriously affecting the service life and application effect of the chromatographic column, and increasing the cost of use and the difficulty of maintenance.

[0009] (3) Equilibrium constraints. Conventional chromatography requires operation in a stable external environment and in an equilibrium state. In addition, due to the relatively small column height and diameter, it cannot efficiently process large-mass and large-volume samples, resulting in significant difficulties in its application in the separation field and limiting the scope of application of chromatography technology.

[0010] (4) Energy consumption challenge. Although some advanced chromatography systems combine temperature control and electric field control technologies to improve separation efficiency under equilibrium conditions, the high energy consumption problem undoubtedly increases the cost of analysis or separation, which is not conducive to energy conservation, environmental protection, and large-scale promotion and application. Summary of the Invention

[0011] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a multi-stage gradient magnetic field device for ultra-long liquid chromatography separation and an auxiliary separation method thereof.

[0012] The technical solutions of the present invention are as follows:

[0013] A multi-stage gradient magnetic field device for ultra-long liquid chromatography separation, comprising a chromatography separation system and a magnetic field auxiliary system;

[0014] The chromatographic separation system comprises a pulse sampling device, a first peristaltic pump, a chromatographic column, a second peristaltic pump, a sampling controller and a pulse sampling device which are arranged in sequence;

[0015] The magnetic field auxiliary system includes a strong magnetic ring which is sleeved on the chromatographic column.

[0016] As a preferred embodiment of the present invention, the chromatographic column uses a silicone rubber tube as a filling column, which is filled with acrylic balls.

[0017] As a preferred solution of the present invention, the material of the strong magnetic ring is neodymium iron boron, and the magnetic field strength of each strong magnetic ring is 150-230mT.

[0018] As a preferred solution of the present invention, the strong magnetic rings are sleeved on the chromatographic column according to a distance gradient.

[0019] As a preferred embodiment of the present invention, the distances between adjacent strong magnetic rings are distributed in an arithmetic progression from dense to sparse. Specifically, a total of 20 strong magnetic rings are provided, and the adjacent distances are 0.0, 15.0, 19.2, 23.4, 27.6, 31.8, 36.0, 40.2, 44.4, 48.6, 52.8, 57.0, 61.2, 65.4, 69.6, 73.8, 78.0, 82.2, 86.4, and 90.6 cm.

[0020] As a preferred embodiment of the present invention, the direction of movement of the pulsed water flow during chromatographic separation is the same as the direction of the magnetic ring from the S pole to the N pole.

[0021] The present invention further discloses an auxiliary separation method of the multi-stage gradient magnetic field device as described above, comprising the following steps:

[0022] S1: When the solution is delivered to the chromatographic column by the first peristaltic pump through the pulse injector, the ions in the chromatographic column will be blocked by the ions in the column packing. Different ions in the solution will exhibit different motion states, with larger ions moving slower than lighter ions.

[0023] S2: After the solution enters the chromatographic column and completes the separation process, the peristaltic pump maintains operation, while the pulse injection device switches to air pumping mode. When the ions in the chromatographic column flow through the influence area of ​​the strong magnetic ring, because ions of different valence states exhibit different magnetic properties, the movement speed of ions with high valence will be lower than that of ions with similar mass but low valence. The gradient distribution of the magnetic ring strengthens this effect, thereby enabling precise control of the movement state of the target ions.

[0024] S3: The outflow end of the chromatographic column collects the ions according to their different peak times, and the impurity ions return to the original solution pool;

[0025] S4: When the air segment enters the chromatographic column and pushes the previous pulse solution to completely flow out of the chromatographic column, the pulse injection device will switch to the pump liquid mode again and continue to cycle through the above three steps until a sufficient amount of target ion enrichment solution is collected.

[0026] As a preferred embodiment of the present invention, the solution is in-situ salt lake water or seawater containing lithium and uranium.

[0027] As a preferred embodiment of the present invention, the flow rate of the solution is controlled at 10-20 ml / min.

[0028] The beneficial effects of the present invention are:

[0029] Generally, the length of a liquid chromatography column does not exceed 300 mm, while the chromatographic column of the present invention is as long as 10 m, which is an ultra-long liquid chromatography column. Therefore, the present invention provides a multi-stage gradient magnetic field device for ultra-long liquid chromatography separation and an auxiliary separation method thereof.

[0030] This paper successfully constructed a dynamic separation and analysis system that combines pulsed injection for precise spatiotemporal control with multi-stage magnetic field gradients for enhanced separation. By introducing an external magnetic field, this system precisely controls the movement of ions within the chromatographic system, effectively separating target ions from a large number of impurity ions under non-equilibrium conditions, thereby achieving highly efficient analysis.

[0031] In this invention, the external magnetic field introduced is a strong permanent magnet, significantly reducing the cost of auxiliary energy equipment. Furthermore, through in-depth research on the synergistic effect of multi-stage gradient magnetic field mechanisms and chromatographic packing, the system is able to accurately analyze the different characteristics exhibited by ions of different valence states during their movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the operating structure of the auxiliary magnetic field device of a preferred embodiment of the present invention; in the figure, 1-filler, 2-chromatographic column, 3-yarn core filter, 4-pulse injection device, 5-strong magnetic ring, 6-inlet and outlet controller, 7-first peristaltic pump, 8-pulse sample outlet device, 9-second peristaltic pump;

[0033] Figure 2 This is a diagram of an acrylic packed column;

[0034] Figure 3 Schematic diagram of a chromatographic column set up with a strong magnetic ring;

[0035] Figure 4 Schematic diagram of the magnetic field direction arrangement;

[0036] Figure 5 Schematic diagram of the device channel (pulse injection, controlled diversion) for the salt lake uranium and lithium co-extraction experiment;

[0037] Figure 6 Schematic diagram of the multi-level gradient magnetic ring distribution in the salt lake uranium and lithium co-extraction experiment; (a): Schematic diagram of the equidistant distribution of strong magnetic rings; (b): Schematic diagram of the gradient distribution of strong magnetic rings from dense to sparse;

[0038] Figure 7 The ion motion distribution in the salt lake uranium-lithium co-extraction experiment without a magnetic field; (a): distribution of lithium ions and uranyl ions; (b): distribution of magnesium ions, sodium ions, and calcium ions; (c): trends in the magnesium-to-lithium ratio and the uranium-to-lithium ratio; (d): trends in the sodium-to-lithium ratio and the calcium-to-lithium ratio.

[0039] Figure 8Figure 2 shows the ion motion distribution state under the SN-type arrangement of ring magnets in the salt lake uranium-lithium co-extraction experiment; (a): The distribution state of lithium ions and uranyl ions under equidistant arrangement; (b): The distribution state of magnesium ions, sodium ions, and calcium ions under equidistant arrangement; (c): The changing trend of the magnesium-lithium ratio and the uranium-lithium ratio under equidistant arrangement; (d): The changing trend of the sodium-lithium ratio and the calcium-lithium ratio under equidistant arrangement; (e): The distribution state of lithium ions and uranyl ions under a gradient arrangement from dense to sparse; (f): The changing trend of the magnesium-lithium ratio and the uranium-lithium ratio under a gradient arrangement from dense to sparse.

[0040] Figure 9 Figure 1 shows the ion motion distribution state under the NS-type equidistant arrangement of ring magnets in the salt lake uranium and lithium co-extraction experiment; (a) distribution of lithium ions and uranyl ions; (b) distribution of magnesium ions, sodium ions, and calcium ions; (c) trends in the magnesium-to-lithium ratio and the uranium-to-lithium ratio; (d) trends in the sodium-to-lithium ratio and the calcium-to-lithium ratio.

[0041] Figure 10 Results of a five-stage separation experiment of uranium and lithium from salt lakes using an SN-type annular magnetic field; (a) The changing trend of the magnesium-lithium ratio in the lithium extraction channel; (b) The changing trend of the uranium-lithium ratio in the lithium extraction channel; (c) The changing trend of the magnesium-lithium ratio in the uranium extraction channel; (d) The changing trend of the uranium-lithium ratio in the uranium extraction channel;

[0042] Figure 11 Schematic diagram of the principle of how SN-type annular magnetic field affects ion motion. DETAILED DESCRIPTION

[0043] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it should not be understood as a limitation on the scope of protection of the present invention.

[0044] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0045] In the description of the present invention, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0046] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0047] Reference Figures 1 to 4 , the preferred embodiment of the present invention:

[0048] A multi-stage gradient magnetic field device for ultra-long liquid chromatography separation, comprising a chromatography separation system and a magnetic field auxiliary system;

[0049] The chromatographic separation system comprises a pulse sampling device 4, a first peristaltic pump 7, a chromatographic column 2, a second peristaltic pump 9, a sample inlet and outlet controller 6 and a pulse sampling device 8 which are arranged in sequence;

[0050] The magnetic field auxiliary system includes a strong magnetic ring, which is sleeved on the chromatographic column 2.

[0051] This embodiment introduces an external magnetic field to precisely intervene in the movement of ions in the chromatographic system, thereby effectively separating the target ions from a large number of impurity ions under non-equilibrium conditions, thereby achieving efficient analysis.

[0052] As a preferred embodiment of the present invention, it may also have the following additional technical features:

[0053] The chromatographic column uses a silicone rubber tube as a filling column with an outer diameter of 9 mm, an inner diameter of 5 mm, and a length of 10 m. The tube is filled with acrylic balls. In specific applications, the diameter of the acrylic balls is 1 mm.

[0054] The strong magnetic rings are arranged on the chromatographic column in a gradient from dense to sparse. Specifically, the strong magnetic rings are made of neodymium iron boron, and the magnetic field strength of each strong magnetic ring is 150-230 mT. The distances between adjacent strong magnetic rings are distributed in an arithmetic progression from dense to sparse. Specifically, a total of 20 strong magnetic rings are provided, and the adjacent distances are 0.0, 15.0, 19.2, 23.4, 27.6, 31.8, 36.0, 40.2, 44.4, 48.6, 52.8, 57.0, 61.2, 65.4, 69.6, 73.8, 78.0, 82.2, 86.4, and 90.6 cm.

[0055] During chromatographic separation, the direction of movement of the pulsed water flow is the same as the direction of the magnetic ring from the S pole to the N pole.

[0056] During specific implementation, a sand core filter port 3 is provided at the liquid outlet end of the chromatographic column 2 .

[0057] The assisted separation method of a multi-stage gradient magnetic field device comprises the following steps:

[0058] S1: When the solution is delivered to the chromatographic column by the first peristaltic pump through the pulse injector, the ions in the chromatographic column will be blocked by the ions in the column packing. Different ions in the solution will exhibit different motion states, with larger ions moving slower than lighter ions.

[0059] S2: After the solution enters the chromatographic column and completes the separation process, the peristaltic pump maintains operation, while the pulse injection device switches to air pumping mode. When the ions in the chromatographic column flow through the influence area of ​​the strong magnetic ring, because ions of different valence states exhibit different magnetic properties, the movement speed of ions with high valence will be lower than that of ions with similar mass but low valence. The gradient distribution of the magnetic ring strengthens this effect, thereby enabling precise control of the movement state of the target ions.

[0060] S3: The outflow end of the chromatographic column collects the ions according to their different peak times, and the impurity ions return to the original solution pool;

[0061] S4: When the air segment enters the chromatographic column and pushes the previous pulse solution to completely flow out of the chromatographic column, the pulse injection device will switch to the pump liquid mode again and continue to cycle through the above three steps until a sufficient amount of target ion enrichment solution is collected.

[0062] As a preferred embodiment of the present invention, the solution is in-situ salt lake water or seawater containing lithium and uranium.

[0063] As a preferred embodiment of the present invention, the flow rate of the solution is controlled at 10-20 ml / min.

[0064] The following embodiments of the present invention are described in detail. The embodiments described below are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this field or the product specifications are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be obtained commercially.

[0065] 1. Temperature: Since this example focuses on in-situ salt lake extraction, room temperature (20-25°C) is considered the optimal experimental condition. Excessively low temperatures may cause cations in the salt lake water to crystallize, thereby weakening separation efficiency. Conversely, excessively high temperatures, given that the filler beads are made of polymethyl methacrylate (i.e., acrylic), may cause filler deformation, which would also be detrimental to separation performance.

[0066] The composition of the in-situ salt lake is shown in Table 1.

[0067] Table 1 Main salt lake types, lithium resource reserves and brine chemical composition in my country

[0068]

[0069] The present invention specifically tests the ion concentration of the simulated Dongtai Jinaier Salt Lake, with a pH of about 8.0.

[0070] 2. Solution Flow Rate: Based on in-depth research in assisted kinetic liquid chromatography, the optimal flow rate for separation has been precisely calculated to be 16 mL / min. Taking into account the column's solution capacity, processing efficiency, and experimental time, a single pulse injection volume of 20 mL was used, resulting in an injection time of 75 seconds. To ensure sufficient intervals between pulses, the air inlet time was set to 100 seconds, ensuring a smooth and efficient separation process.

[0071] 3. pH: In view of the acid and alkali resistance range of acrylic, there will be no change in any physical and chemical properties within the pH range of 3-11.

[0072] 4. Column packing size: Use 1mm acrylic beads. If the diameter is too small, the water flow efficiency will be extremely low due to the 10-meter length of the column. If the diameter is too large, the separation unit in the column will not be able to fully utilize its blocking effect on different ions.

[0073] 5. Magnetic field strength: accurately measured by a Gauss meter, and the average magnetic field strength of a strong annular magnet is 200mT.

[0074] Since this embodiment adopts the switching injection mode of liquid flow-air-liquid flow mode, this dynamic pulse injection is the key step to achieve nuclide separation. Therefore, the designed liquid flow switching controller needs to have the ability to control the injection end and the output end at the same time ( Figure 5 and Figure 6 ).

[0075] Specifically, take the simultaneous extraction of lithium and uranium resources from salt lakes as an example. Two independent channels, liquid flow and air, are designed at the injection end to realize the "liquid-gas-liquid" pulse injection mode. The specific operation process is as follows: the chromatographic column is first connected to the liquid channel, and the duration of the sample liquid is set to T1; then it is quickly switched to the air channel, and the time for the air to be introduced is set to T2; after the air is introduced, it is immediately switched back to the liquid channel again, and the sample liquid is continued to be introduced, and the duration is also T1. This process realizes a dynamic and reciprocating pulse injection method through alternating circulation between the liquid flow and the air channel.

[0076] At the sample outlet, two different enriched liquid channels and a lean liquid channel are set. The sample outlet channels set in this embodiment correspond to the uranium channel, the lithium channel, and the lean liquid channel. When a section of solution pulse sample liquid arrives at the sample outlet, the liquid level sensor reserved by the effluent control switch at the sample outlet will immediately sense it and light up the red indicator light. At this time, the sample liquid flows out of the lean liquid channel for T3 time; after the end, the sample liquid is switched to flow out of the lithium channel for T4 time; when the T4 time is over, the sample liquid switches to flow out of the uranium channel for T5 time; after the T5 time is over, the sample outlet is switched to the lean liquid channel again until the rear end turbulent liquid of this pulse is drained. When the liquid level sensor cannot sense the liquid flow, the red indicator light goes out, and the sample outlet is reset until the next section of pulse sample liquid arrives at the sample outlet and is sensed by the liquid level sensor. The sample outlet cycles according to the above part. See Table 2 for specific settings.

[0077] Table 2 Setting values ​​of separation device T in the experiment

[0078] time T1(s) T2(s) T3(s) T4(s) T5(s) Setting value 75 100 21 25 20

[0079] Experiment 1: Conducting a simultaneous extraction experiment of uranium and lithium from a salt lake without an external magnetic field;

[0080] The ion distribution state of the chromatographic column filled with acrylic beads in the absence of a magnetic field is as follows: Figure 7 In the absence of magnetic ring assistance, according to Figure 7 (a) in Li + It is basically at the front end of the pulse peak, and UO2[CO3]3 4- Basically, the peak appears at the middle and back end of the pulse. Figure 7 In (c), the magnesium-lithium ratio shows a trend of gradually decreasing. Therefore, the node suitable for magnesium-lithium separation is between 10mL-20mL. On the other hand, for U / Li, the node suitable for U-Li separation is basically between 10mL-20mL. This makes it impossible to achieve uranium-lithium separation while achieving magnesium-lithium separation, which is not conducive to the simultaneous extraction of uranium and lithium. That is, for lithium and uranium, the peak node of lithium is basically at the front end of a pulse (2mL-10mL), while the peak node of uranium is basically close to the middle and back end of a pulse (10mL-20mL). The fluctuation trends of other cations are relatively similar. This is because in a weakly alkaline solution, uranium will exist in the form of uranyl carbonate complex anions. In the absence of external effects, the movement state of the ions is mainly affected by the liquid film on the surface of the filler beads in the chromatographic column, UO2[CO3]3 4- The mass of uranium is the largest, so the blocking effect in the liquid film is greater, so the peak node is later. However, it is observed that the mass concentration ratio of uranium to lithium (C U / C Li ) also shows a trend of low at the beginning and high at the end, C Mg / C LiIt shows a trend of high at the beginning and low at the end. Without external assistance, it is impossible to extract uranium and lithium separately and simultaneously.

[0081] Experiment 2: Conducting a simultaneous extraction experiment of uranium and lithium from a salt lake with an external toroidal magnetic field (first magnetic pole arrangement: “SN” type);

[0082] See the results Figure 8 , in the SN type magnetic ring auxiliary environment, Figure 8 The magnetic rings (a)-(d) are evenly distributed according to Figure 8 (a) in Li + It is basically in the middle of the pulse front end, and UO2[CO3]3 4- The main peak is at the back end of the pulse. Figure 8 In (c), the Mg / Li peak is low at the 2mL-10mL node, making this region suitable for magnesium-lithium separation. Similarly, the main peak for U / Li peak lies within the 10mL-18mL node. Because the separation nodes for Mg / Li and U / Li are different, this magnetic field-assisted environment facilitates the simultaneous extraction of lithium and uranium.

[0083] Figure 8 (e) and (f) are the ion motion distribution states under the SN type magnetic ring assisted environment (magnetic ring gradient distribution from dense to sparse). Figure 8 In (e), UO2[CO3]3 can be clearly found 4- The peak node of Li is at the back end of the pulse, and + The peak node is in the middle of the pulse. Figure 8 Figure (f) clearly shows that the Mg / Li ratio decreases gradually between 2mL and 10mL, reaching a peak-valley point. This demonstrates that this volume node is suitable for magnesium-lithium separation, while the peak of U / Li occurs between 10mL and 20mL. Therefore, the separation nodes for Mg / Li and U / Li remain distinct, and the effect is even better than that of the equally spaced magnetic rings because the range of separable and extractable volume nodes is larger, which is equivalent to improved separation efficiency.

[0084] Experiment 3: Conducting an experiment on the simultaneous extraction of uranium and lithium from a salt lake with an external circular magnetic field (the second magnetic pole arrangement: "NS" type).

[0085] See the results Figure 9 Compared with the results of the "SN" type arrangement, when the ring magnet is reversed (i.e., the "NS" type arrangement), the experimental results show significant differences. The most obvious difference is that the motion state of each ion becomes highly similar, which makes it difficult to achieve synchronous extraction of lithium and uranium. Figure 9 The data in (a) and (b) are Figure 9The peak trends of the two ions in (a) show that the fluctuation times and amplitudes are similar. It can also be observed that under this magnetic field condition, the large mass uranyl ion has a peak at the front end of the pulse. At the same time, Li + The front end is collided and squeezed by large mass ions such as uranyl, and its peak trend shows greater and more frequent fluctuations. In addition, the mass concentration ratio of magnesium and lithium shows three obvious fluctuations in this process, which is not conducive to multi-stage separation experiments. Figure 9 In (c), the trends of U / Li and Mg / Li show multiple fluctuations, with neither showing a long volume node suitable for separation. This is because the magnetic pole reversal affects ion motion, making the NS type unfavorable for the simultaneous extraction of uranium and lithium.

[0086] Therefore, the "SN" type arrangement is more conducive to the simultaneous extraction of uranium and lithium.

[0087] The main reason for the different results of the two arrangements is the change in the direction of the magnetic field polarity. Although the liquid film exists throughout the experiment and the magnetic field does not damage its surface, the different directions of the magnetic field obviously change the movement of ions in the chromatographic column. Specifically, the change in the direction of the magnetic field may affect the migration path and speed of the ions, thereby affecting the overall separation efficiency. The schematic diagram can be referred to Figure 11 .

[0088] Experiment 4: Conduct a five-stage separation experiment of uranium and lithium from salt lakes with an external "SN" type annular magnetic field.

[0089] The results are as follows Figure 10 As shown, Figure 10 As shown in (b), for salt lake water with a high magnesium-lithium ratio, only five stages of chromatographic column separation (five separations using one set of equipment), which can also be five sets of equipment designed in series, can show a very obvious magnesium-lithium separation effect, and the magnesium-lithium ratio is greatly reduced. In particular, the maximum separation factor is reached at the fourth stage of separation. The maximum magnesium-lithium separation factor α is experimentally measured to be 1.202, and the maximum uranium-lithium separation factor reaches 1.088. Moreover, if the ideal separation goal of reducing the magnesium-lithium ratio from 200 to 20 is to be achieved, only 13 stages of separation are required, which fully demonstrates that this chromatographic column separation method has significant separation efficiency in treating salt lake water with a high magnesium-lithium ratio.

[0090] In summary, the present invention has a total of 20 levels of magnetic ring-assisted separation on a 10m chromatographic column (belonging to ultra-long liquid chromatography), and there are three modes of distribution of magnetic rings: one is equidistant distribution, that is, the distance between adjacent magnetic rings is 50cm; the second is a gradient distribution from dense to sparse, and the distances between adjacent strong magnetic rings are distributed according to an arithmetic progression gradient, which are 0.0, 15.0, 19.2, 23.4, 27.6, 31.8, 36.0, 40.2, 44.4, 48.6, 52.8, 57.0, 61.2, 65.4, 69.6, 73.8, 78.0, 82.2, 86.4, and 90.6cm respectively; the third is a gradient distribution from sparse to dense, and the distances between adjacent strong magnetic rings are opposite to those in the second case.

[0091] Through repeated experiments, in conjunction with the objectives of the present invention, it was found that when the water flow direction coincides with the direction of the magnetic ring from the south pole to the north pole, it is beneficial for the simultaneous separation and extraction of uranium and lithium from salt lakes or seawater; whereas when the water flow direction is opposite to the direction of the magnetic ring from the south pole to the north pole, it is detrimental to the simultaneous separation and extraction of uranium and lithium from salt lakes or seawater. Furthermore, when the water flow direction coincides with the direction of the magnetic ring from the south pole to the north pole, the second type of gradient distribution (from dense to sparse) is most beneficial for the simultaneous separation and extraction of uranium and lithium from salt lakes or seawater, followed by the first type of equidistant distribution, and finally the third type of gradient distribution (from sparse to dense).

[0092] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0093] The above-described embodiments merely represent preferred implementations of the present invention. While the descriptions thereof are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various other corresponding changes and modifications based on the technical solutions and concepts described above, and all such changes and modifications should fall within the scope of protection of the claims of the present invention.

Claims

1. A multi-stage gradient magnetic field device for ultra-long liquid chromatography separation, characterized in that: Including chromatographic separation system and magnetic field auxiliary system; The chromatographic separation system comprises a pulse sampling device, a first peristaltic pump, a chromatographic column, a second peristaltic pump, a sampling controller and a pulse sampling device which are arranged in sequence; The magnetic field auxiliary system includes a strong magnetic ring which is sleeved on the chromatographic column.

2. A multi-stage gradient magnetic field device for ultra-long liquid chromatography separation according to claim 1, characterized in that: The chromatographic column uses a silicone rubber tube as a filling column, which is filled with acrylic balls.

3. A multi-stage gradient magnetic field device for ultra-long liquid chromatography separation according to claim 1, characterized in that: The material of the strong magnetic ring is neodymium iron boron, and the magnetic field strength of each strong magnetic ring is 150-230mT.

4. The multi-stage gradient magnetic field device for ultra-long liquid chromatography separation according to claim 1, characterized in that: The strong magnetic ring is sleeved on the chromatographic column according to a distance gradient.

5. The multi-stage gradient magnetic field device for ultra-long liquid chromatography separation according to claim 4, characterized in that: The distances between adjacent strong magnetic rings are distributed in an arithmetic progression from dense to sparse. There are a total of 20 strong magnetic rings, and the adjacent distances are 0.0, 15.0, 19.2, 23.4, 27.6, 31.8, 36.0, 40.2, 44.4, 48.6, 52.8, 57.0, 61.2, 65.4, 69.6, 73.8, 78.0, 82.2, 86.4, and 90.6 cm.

6. The multi-stage gradient magnetic field device for ultra-long liquid chromatography separation according to claim 1, characterized in that: During chromatographic separation, the direction of movement of the pulsed water flow is the same as the direction of the magnetic ring from the S pole to the N pole.

7. An auxiliary separation method of a multi-stage gradient magnetic field device according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: When the solution is delivered to the chromatographic column by the first peristaltic pump through the pulse injector, the ions in the chromatographic column will be blocked by the ions in the column packing. Different ions in the solution will exhibit different motion states, with larger ions moving slower than lighter ions. S2: After the solution enters the chromatographic column and completes the separation process, the peristaltic pump maintains operation, while the pulse injection device switches to air pumping mode. When the ions in the chromatographic column flow through the influence area of ​​the strong magnetic ring, due to the different magnetic properties exhibited by ions of different valence states, the movement speed of ions with high valence states will be lower than that of ions with similar mass but low valence states. The gradient distribution of the magnetic ring strengthens this effect, thereby enabling precise control of the movement state of the target ions. S3: The outflow end of the chromatographic column collects the ions according to their different peak times, and the impurity ions return to the original solution pool; S4: When the air segment enters the chromatographic column and pushes the previous pulse solution to completely flow out of the chromatographic column, the pulse injection device will switch to the pump liquid mode again and continue to cycle through the above three steps until a sufficient amount of target ion enrichment solution is collected.

8. The auxiliary separation method according to claim 7, characterized in that: The solution is in-situ salt lake water or seawater containing lithium and uranium.

9. The auxiliary separation method according to claim 7, characterized in that: The flow rate of the solution is controlled at 10-20 ml / min.

Images