Leaching simulation method

Abstract

The invention discloses a leaching simulation method, and relates to the technical field of mine environmental engineering and geochemistry, and the leaching simulation method comprises the following steps: collecting an undisturbed soil sample; filling the undisturbed soil sample in an equal-proportion layering manner to form a soil column; measuring mineralogical data of the comparison sample and geochemical data of rare earth elements; leaching the soil column by using a leaching solution, and taking a soil sample after leaching and a leaching solution sample; measuring mineralogical data and geochemical data of rare earth elements in the leached soil sample, measuring geochemical data of the rare earth elements in the leachate sample, and comparing the geochemical data of the rare earth elements in the sample and the leached soil sample with one or more of content, chemical valence, occurrence form and occurrence carrier; the change of the content and form of rare earth elements in a soil sample under natural rainfall conditions and underground water power can be simulated, so that the processes of redistribution of the rare earth elements in a weathering crust and combination with an underground water solution for carrying are monitored, and a migration mechanism empirical evidence is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of mine environmental engineering and geochemistry, in particular to a leaching simulation method. Background Art

[0002] Since their first discovery in Jiangxi Province in the last century, ion-adsorption rare earth (REE) deposits have attracted widespread attention from geologists both domestically and internationally regarding their mineralization mechanisms. The formation of ion-adsorption REE deposits can be summarized as follows: Easily weatherable REE-rich minerals in the parent rock release REE ions through intense chemical weathering under warm, humid climates. These ions are transported by groundwater within the weathering crust and ultimately adsorbed and aggregated by clay minerals, forming rare earth mineral deposits. It is currently widely believed that abundant rainfall in South China provides a key geological driver for the surface migration of REEs. Driven by continuous water-rock interactions, REEs migrate and redistribute throughout the weathering crust in various forms, including ions, nanoscale colloids, and complexes. Despite significant theoretical breakthroughs in understanding the properties of ore-forming parent rocks, the developmental characteristics of weathering crusts, and the occurrence patterns and influencing factors of REEs, gaps remain in our understanding of the microscopic migration mechanisms of REEs within the weathering crust. Existing research remains largely theoretical, lacking empirical support for dynamic migration processes. The lack of empirical evidence for the migration mechanism has greatly hindered the understanding of the mineralization mechanism of ion adsorption-type rare earth minerals and the development of exploration technology. Summary of the Invention

[0003] The purpose of the present invention is to provide a leaching simulation method to solve the problems existing in the above-mentioned prior art. It can simulate the changes in the content and form of rare earth elements in soil samples under natural rainfall conditions and groundwater dynamics, so as to monitor the desorption and re-adsorption process of rare earth elements inside the weathering crust and the process of their transportation in combination with groundwater solutions, and provide empirical evidence of the migration mechanism.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a leaching simulation method, comprising the following steps:

[0006] Sample collection steps: Collect undisturbed soil samples and record soil profile information;

[0007] Soil sample filling step: filling the soil layers to be tested into the leaching device in equal proportions according to the thickness of the original soil samples taken in the sample collection step, or directly filling the soil samples at specific layers, controlling the filling density to be ±5% of the original soil bulk density, to form a soil column;

[0008] Comparative sample determination step: using the remaining unfilled portion of the soil layer to be tested as a comparative sample, and determining the mineralogical data and geochemical data of rare earth elements of the comparative sample;

[0009] Leaching experiment steps: using the prepared leachate to leach the soil column loaded in the soil sample loading step, taking leached soil samples and leachate samples at different thicknesses of the soil column according to a preset time gradient, and collecting leachate samples flowing out from the bottom of the soil column;

[0010] Post-experimental sample determination step: determining the mineralogical data and geochemical data of rare earth elements in the leached soil sample, and determining the geochemical data of rare earth elements in the leachate sample; the geochemical data of rare earth elements in the comparison sample and the leached soil sample include: one or more of the content of rare earth elements, the chemical valence of rare earth elements, the occurrence form of rare earth elements, and the occurrence carrier of rare earth elements.

[0011] In some embodiments, the soil sample filling step specifically includes: selecting a leaching device that is compatible with the diameter of the original soil sample taken out in the sample collection step; determining the layered filling thickness of different soil layers and the distribution of different soil layers based on the thickness of the original soil sample taken out in the sample collection step and the thickness and distribution order of different soil layers in the original soil sample; accurately weighing and filling and compacting the soil sample in layers.

[0012] In some embodiments, the mineralogical data of the comparative sample and the leached soil sample include: one or more of the type of minerals in the soil sample, the crystal structure of the minerals, and the microscopic morphology of the minerals; the geochemical data of the rare earth elements in the leachate sample include: one or more of the rare earth element content, anion and cation content, pH value, redox potential, conductivity, organic acid and rare earth complex content, colloid type, and colloid morphology and elemental composition.

[0013] In some embodiments, the leaching device includes: a leaching body, a liquid supply device and a liquid collecting device, the leaching body, the leaching body having a cavity, the cavity being used to hold a soil sample, a liquid inlet being provided at the top of the cavity, a liquid outlet being provided at the bottom of the cavity, a plurality of sampling ports being provided on the side wall of the leaching body connected to the interior of the cavity, and the sampling ports being detachably provided with valves; the liquid supply device being connected to the liquid inlet and being used to provide leaching liquid to the soil sample in the cavity; the liquid collecting device being connected to the liquid outlet, and being used to collect the leaching liquid sample flowing out of the liquid outlet.

[0014] In some embodiments, the liquid inlet and the liquid outlet have a height difference in the vertical direction, and the sampling port is located on the side wall of the leaching body between the liquid inlet and the liquid outlet, and a plurality of the sampling ports are provided in the vertical direction.

[0015] In some embodiments, the leaching body includes a leaching tube, which includes several leaching columns, each of which has a cavity with openings at both ends, and each of the leaching columns is vertically distributed and can be connected and communicated in sequence through the openings. The connected several cavities form the cavity, and the sampling ports are evenly opened on the side walls of each of the leaching columns; the leaching body also includes a support frame, which is used to support the leaching tube and to ensure a height difference between the leaching tube and the bottom surface of the support frame.

[0016] In some embodiments, the leaching pipe further comprises a leakage trough, the top opening of the leakage trough being connected to the bottom opening of the leaching pipe, a first supporting structure being provided in the leakage trough, the first supporting structure being axially fixed in the leakage trough and used to support the soil sample in the leaching pipe, a plurality of first through holes for the passage of the leachate being evenly provided on the first supporting structure, a space for accommodating the leachate being provided between the first supporting structure and the bottom surface of the leakage trough, and the liquid outlet being provided on the bottom surface of the leakage trough; a second supporting structure being provided in the leaching column, the second supporting structure being axially fixed in the leaching column and used to support the soil sample in the leaching column, a plurality of second through holes for the passage of the leachate being evenly provided on the second supporting structure; the first supporting structure is covered with a first filter layer, and the sampling port is covered with a second filter layer.

[0017] In some embodiments, the liquid supply device includes a rainfall device, which is fixedly arranged above the leaching pipe and is used to spray the leaching liquid onto the soil sample in the cavity.

[0018] In some embodiments, the liquid supply device also includes a liquid supply tank and a drive adjustment device. The liquid supply tank is connected to the rainfall device through a first pipeline. The drive adjustment device is arranged on the first pipeline. The drive adjustment device is used to drive the delivery of the leachate and control the delivery speed and time of the leachate. The rainfall device includes a liquid storage cavity, and several leakage ports are evenly arranged at the bottom of the liquid storage cavity. The leachate can flow into the cavity through the leakage ports. A first sensor is provided in the liquid storage cavity. The first sensor is used to detect the liquid level in the liquid storage cavity. The first sensor is connected to the drive adjustment device signal.

[0019] In some embodiments, the liquid collecting device includes a liquid collecting bottle and a gas suction device, the liquid collecting bottle has a first inlet and a first outlet, the first inlet and the first outlet are both arranged at the top of the liquid collecting bottle, the first inlet is connected to the liquid outlet, and the first outlet is connected to the gas suction device; a second sensor is provided in the liquid collecting bottle, the second sensor is used to detect the liquid level in the liquid collecting bottle, and the second sensor is connected to the gas suction device signal.

[0020] Compared with the prior art, the present invention has achieved the following technical effects:

[0021] The leaching simulation method provided by the present invention can simulate the changes in the content and form of rare earth elements in soil samples under natural rainfall conditions and groundwater dynamics to monitor the process of rare earth elements being transported in combination with groundwater solutions. Leached soil samples are obtained from different positions of the soil column according to a preset time gradient to obtain the existence form and content of rare earth elements in the leached soil samples at different positions. This allows for a detailed comparison of the change data of the mineralogical data of the weathering crust and the geochemical data of the rare earth elements before and after leaching according to the passage of leaching time. At the same time, leachate samples are obtained from different positions of the soil column according to the passage of leaching time, and leachate samples are obtained from the bottom of the soil column. The existence form and content of the rare earth elements in the leachate samples are analyzed, and the migration and differentiation laws of light / heavy rare earth elements within the weathering crust are further summarized, providing theoretical support and empirical evidence for the mineralization mechanism and exploration technology of rare earth minerals. Moreover, by analyzing and comparing the content of rare earth elements in samples and leached soil samples, the chemical valence of rare earth elements, the occurrence form of rare earth elements, and the occurrence carriers of rare earth elements, we can more clearly understand the existence form and migration results of rare earth elements inside the weathering crust, which is further conducive to summarizing the migration and differentiation rules of light / heavy rare earth elements inside the weathering crust. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0023] Figure 1 This is a flow chart of the implementation of the leaching simulation method in Example 1;

[0024] Figure 2 Schematic diagram of the leaching device in Example 2.

[0025] In the figure: 11-liquid supply tank; 12-first pipeline; 13-peristaltic pump; 14-rainfall device; 141-liquid storage chamber; 142-first sensor; 21-leaching column; 211-sampling port; 212-valve; 22-leakage trough; 23-support frame; 24-liquid inlet; 25-liquid outlet; 31-liquid collecting bottle; 311-second sensor; 32-first inlet; 33-first outlet; 34-vacuum pump. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] The purpose of the present invention is to provide a leaching simulation method to solve the problems existing in the prior art. It can simulate the changes in the content and form of rare earth elements in soil samples under natural rainfall conditions and groundwater dynamics, so as to observe the redistribution of rare earth elements within the weathering crust and their transportation in combination with groundwater solutions, and provide empirical evidence of the migration mechanism.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the following Figures 1-2 The present invention is further described in detail with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] This embodiment provides a leaching simulation method. The implementation process is referenced Figure 1 , including the following steps:

[0031] Sample collection steps: Collect undisturbed soil samples and record soil profile information;

[0032] Soil sample filling step: according to the thickness of the original soil sample taken in the sample collection step, the soil layer to be tested is filled in the leaching device in equal proportions, or the soil sample of a specific soil layer is directly filled, and the filling density is controlled to be ±5% of the original soil bulk density to form a soil column;

[0033] Comparative sample determination steps: taking the remaining unfilled portion of the soil layer to be tested as a comparative sample, and determining the mineralogical data and geochemical data of rare earth elements of the comparative sample;

[0034] Leaching experiment steps: Use the prepared leachate to leach the soil column filled in the soil sample filling step, collect leached soil samples and seeped leachate samples at different thicknesses of the soil column according to the preset time gradient, and collect leachate samples flowing out from the bottom of the soil column at the same time;

[0035] Post-experimental sample determination steps: determine the mineralogical data and geochemical data of rare earth elements in the leached soil sample, and determine the geochemical data of rare earth elements in the leachate sample; the geochemical data of rare earth elements in the comparative sample and the leached soil sample include: one or more of the following: the content of rare earth elements, the chemical valence of rare earth elements, the occurrence form of rare earth elements, and the occurrence carrier of rare earth elements.

[0036] Specifically, when collecting samples, it is necessary to screen out ion adsorption type rare earth deposit weathering crusts with complete weathering profiles (good vertical continuity) and no obvious signs of human disturbance through field exploration on the basis of systematic integration of regional geological data. According to the vertical characteristics of the weathering crust, the topsoil layer, the full weathering layer and the semi-weathering layer are divided into three soil layers. After collecting the undisturbed soil sample, it is immediately packed into a sealed aluminum box and transported to the laboratory to maintain the original structural characteristics of the soil sample. In this embodiment, the sampling is carried out using the Gannan drill according to the geological exploration specification for weathering crust ion adsorption type rare earth minerals (DB36 / T 1158-2019), and other sampling devices can also be selected in some other embodiments. In the soil sample filling step, equal proportion layered filling refers to the thickness and distribution of the field soil layer and the ratio of the soil layer thickness and distribution of the soil sample in the soil column after the experimental filling, or according to the specific experimental needs, the soil sample of the required specific soil layer or the soil layer where the ore body is located is directly loaded into the leaching device. In this embodiment, the leachate is configured based on the South China rainfall data. Leachate samples seeping from different positions of the soil column and leachate samples flowing out from the bottom of the soil column are taken according to the leaching time. Leached soil samples are taken from different positions of the soil column, and leached soil samples are taken from different positions of the soil column according to a preset time gradient to obtain the existence form and content of rare earth elements in the leached soil samples at different positions. This allows for a detailed comparison of the changes in the mineralogical data of the weathering crust and the geochemical data of the rare earth elements before and after leaching according to the passage of leaching time. At the same time, leachate samples seeping from different thicknesses of the soil column and leachate samples from the bottom of the soil column are taken according to the passage of leaching time. The existence form and content of the rare earth elements in the leachate samples are analyzed, and the migration and differentiation laws of light / heavy rare earth elements within the weathering crust are further summarized, providing theoretical support and empirical evidence for the mineralization mechanism and exploration technology of rare earth minerals. Furthermore, by analyzing one or more of the rare earth element content, chemical valence, occurrence form, and occurrence carrier of rare earth elements in the comparative samples and leached soil samples, it is possible to more clearly understand the existence form and migration results of rare earth elements within the weathering crust, which is further conducive to summarizing the migration and differentiation rules of light / heavy rare earth elements within the weathering crust. In this embodiment, the preset time gradient is one month, that is, every one month, soil samples and leached leachate samples at different thicknesses of the soil column are taken, and leachate samples flowing out from the bottom of the soil column are collected at the same time. In other embodiments, the preset time gradient can be determined based on the specific soil column thickness, soil column diameter, and other experimental requirements. In this embodiment, the comparative sample determination step can be started before leaching begins to save time. In other embodiments, the comparative sample determination step can also be performed after leaching is completed. In some other embodiments, the controlled variable method can also be used to change the external environment such as leaching time, light, temperature, etc. to carry out comparative experiments, or the pH or ionic strength of the leachate can be changed to explore the influence of the chemical properties of rainfall on the migration of light / heavy rare earth elements within the weathering crust.Specifically, the occurrence form of rare earth elements refers to the microscopic combination state of rare earth elements and other elements, that is, the specific physical and chemical state, including the combination mode, molecular structure and microscopic distribution characteristics, in the form of rare earth ions (REEs). 3+ ) as an example. The valence state of rare earth elements is usually +3. In the surface stage, the pH of the weathering crust environment is higher than the zero point charge of clay minerals, which makes the surface (interlayer) of clay minerals show negative charge. 3+ Rare earth elements can be captured by clay minerals through surface complexation / adsorption, coprecipitation, and other forms. Of course, the occurrence forms of rare earth elements are not limited to valence states, bonding modes, and microscopic distribution characteristics similar to those of ionic phases; other valence states, bonding modes, and microscopic distribution characteristics are also possible. For example, secondary rare earth phosphate minerals and oxides (cerium, CeO2) particles in the surface environment are widely dispersed within weathering crust profiles. The occurrence carrier of rare earth elements refers to the macroscopic substance or mineral that supports the rare earth elements. For example, rare earth elements in ion-adsorbed form can occur in this form on the surface of kaolinite, halloysite, or montmorillonite clay minerals, and the occurrence carrier is kaolinite, halloysite, or montmorillonite clay minerals. For example, rare earth elements in nano-mineral form can occur as fine particles (<100nm) encapsulated in minerals such as iron-manganese oxides. The occurrence carrier of CeO2 is also a mineral such as iron-manganese oxides. The occurrence carrier of rare earth elements is not limited to the above minerals; other occurrence carriers are also possible. In this embodiment, the main valence states of rare earth elements in the weathering crust, the content of rare earth elements in soil samples, and the binding states of rare earth elements with other elements and carriers are revealed by means of characterization methods such as X-ray photoelectron spectroscopy (XPS) and synchrotron radiation (XAES). After particle size screening, a seven-step sequence is used to extract and identify the occurrence forms of rare earth elements in each particle size. Among them, particle size screening includes but is not limited to mesh screening method, sedimentation method, water jet method and field flow separation method. The seven-step sequence in this embodiment is specifically to sequentially extract the rare earth elements through water, 1 mol·L -1 Magnesium chloride solution, 1 mol·L -1 Sodium acetate solution, 0.1 mol·L -1 Sodium pyrophosphate solution, 0.25 mol·L -1 Hydroxylamine hydrochloride - 0.251 mol·L -1 A mixture of hydrochloric acid, 0.02 mol·L -1 Nitric acid - 30% (volume fraction) Hydrogen peroxide - 1.6 mol·L -1 Ammonium acetate - 1.6 mol·L -1After extraction with a mixed solution of nitric acid, the water-soluble state (F1), ion-exchange state (F2), carbonate-bound state (F3), humic acid-bound state (F4), iron-manganese oxide-bound state (F5), strongly organic-bound state (F6) and residue state (F7) of rare earth elements were obtained. The contents of seven chemical forms of each rare earth element and the total amount of 15 rare earth elements in the samples were determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0037] In some implementations of this embodiment, the soil sample filling step specifically includes: selecting a leaching device that is compatible with the diameter of the original soil sample taken in the sample collection step; determining the layered filling thickness of different soil layers and the distribution of different soil layers based on the thickness of the original soil sample taken in the sample collection step and the thickness distribution of different soil layers in the original soil sample; accurately weighing, filling, and compacting the soil sample in layers. In this embodiment, the sampling device is a Gannan drill. The thickness of the soil sample obtained in the field is 20m. The filling thickness of the soil sample is determined to be 2m according to a ratio of 1:10. The filling thickness and filling position of each soil layer are determined based on the distribution thickness and distribution position of each soil layer in the soil sample to ensure that the filled soil sample is consistent with the soil layer distribution in the field. The different soil layers are then weighed, filled, and compacted in layers using a manual tamping rod to make the filled soil structure closer to the soil structure in the natural state, while also ensuring the repeatability of the experiment. In other embodiments, a layered filling ratio, such as 1:5 or 1:20, can be selected based on the specific field sampling thickness, and a leaching device adapted to the sampling thickness can be selected to support the reconstruction of soil structures of greater thickness. In other embodiments, a pneumatic compaction device can also be used for layered compaction.

[0038] In some embodiments of this embodiment, the mineralogical characteristic data of the comparative sample and the leached soil sample include: one or more of the type of minerals in the soil sample, the crystal structure of the minerals, and the microscopic morphology of the minerals; the geochemical data of the rare earth elements in the leachate sample include: one or more of the rare earth element content, anion and cation content, pH value, redox potential, conductivity, organic acid and rare earth complex content, colloid type, and the morphology and elemental composition of the colloid. Specifically, in determining the mineralogical data of the comparative samples and the leached soil samples, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy (RAM) are used to identify the type and crystal structure of the minerals in the soil samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are used to observe the microscopic morphology of the minerals in the soil samples. In determining the geochemical data of rare earth elements in the leachate samples, ultrafiltration is used to fractionate the dissolved and colloid-bound rare earth elements. Transmission electron microscopy (TEM) is used to characterize the colloid morphology and elemental composition. Liquid chromatography-mass spectrometry (LC-MS) is used to detect organic acids (oxalic acid, citric acid) and rare earth complexes (such as rare earth-organic acid complexes). In other embodiments, multiple stages of filtration membranes can be added to separate the colloid-bound rare earth elements, and an online spectrometer can be introduced to enable real-time monitoring of the leachate sample composition. In this example, the rare earth element content in comparative samples, leached soil samples, and leachate samples was determined, and various data related to rare earth elements were obtained using ultrafiltration classification and particle size, phase analysis, and other means. The obtained data were analyzed to further reveal the synergistic mechanism of rare earth activation and migration in the weathering layer. A multi-component migration model was constructed based on the PHREEQC hydrogeochemical simulation software, and the complex migration parameters of rare earths were fitted. The migration and differentiation laws of light and heavy rare earth elements in the weathering crust were further summarized, providing theoretical support and empirical evidence for the mineralization mechanism and exploration technology of rare earth minerals.

[0039] Example 2

[0040] This embodiment provides a leaching device for implementing the leaching simulation method in embodiment 1, referring to Figure 2The invention comprises a leaching body, a liquid supply device, and a liquid collection device. The leaching body has a cavity for holding a soil sample. After filling, the cavity forms the soil column described in Example 1. The top of the cavity is provided with a liquid inlet 24, and the bottom of the cavity is provided with a liquid outlet 25. The sidewall of the leaching body is provided with a plurality of sampling ports 211 connected to the interior of the cavity. The sampling ports 211 are detachably provided with valves 212. The liquid supply device is connected to the liquid inlet 24 and is used to provide leachate to the soil sample in the cavity. The liquid collection device is connected to the liquid outlet 25 and is used to collect leachate samples flowing out of the liquid outlet 25. The leachate sample refers to the leachate that flows through the soil sample and is removed from the valve 212 or the leachate collected by the liquid collection device. The leaching device provided in this embodiment, by providing a liquid supply device, a leaching body, and a liquid collection device, simulates the leaching of rare earth elements from a weathering crust under natural rainfall conditions. Furthermore, by providing a sampling port 211 on the side wall of the leaching body with a removable valve 212, real-time sampling of leachate and soil samples during and after the experiment is achieved. This allows monitoring of the transport of rare earth elements in combination with groundwater solutions. Soil samples are obtained from different sampling ports 211 according to the leaching time, and the presence and content of rare earth elements in soil samples at different locations and sampling times are determined. This allows for detailed comparison of mineralogical and geochemical data of the weathering crust before and after leaching. Leachate samples are obtained from different valves 212 and the liquid collection device according to a preset leaching gradient, and the presence and content of rare earth elements in leachate samples taken at different locations and times are analyzed. This further summarizes the migration and differentiation patterns of light and heavy rare earth elements within the weathering crust, providing theoretical support and empirical evidence for the mineralization mechanism and exploration technology of rare earth minerals.

[0041] In some implementations of this embodiment, the liquid inlet 24 and the liquid outlet 25 have a vertical height difference, and multiple sampling ports 211 are located on the side wall of the leaching body between the liquid inlet 24 and the liquid outlet 25. By arranging the sampling ports 211 at different heights, it is possible to sample leached soil samples and leachate samples at different thicknesses, thereby expanding the range of experimental data and making the experiment more convincing.

[0042] In some embodiments of this example, the leaching body includes a leaching tube, which includes several leaching columns 21. Each leaching column 21 has a cavity with two open ends. The leaching columns 21 are vertically distributed and can be sequentially connected and connected through the openings. The connected cavities form a cavity. Sampling ports 211 are evenly distributed on the sidewalls of each leaching column 21. The leaching body also includes a support frame 23, which is used to support the leaching tube and to create a height difference between the leaching tube and the bottom surface of the support frame 23. By distributing several leaching columns 21 vertically, soil samples can be loaded according to the height of each leaching column 21, and the distribution of soil layers of different thicknesses can be simulated by increasing or decreasing the number of leaching columns, thereby enhancing the scalability of the experiment. Because the liquid outlet 25 is located at the bottom of the leaching tube, the support frame 23 creates a height difference between the leaching tube and the bottom surface of the support frame 23, preventing the connection between the liquid outlet 25 and the first inlet 32 from being blocked by the action of gravity on the leaching tube, thereby facilitating the smooth outflow of the leachate. In this embodiment, the support frame 23 is directly fixedly connected to the bottom of the leaching pipe. In other embodiments, the support frame 23 can also be detachably connected to other positions of the leaching pipe, such as by connecting the support frame 23 to the middle of the leaching pipe through a hoop.

[0043] In some embodiments of this embodiment, the leaching pipe further includes a leakage trough 22, the top opening of the leakage trough 22 is connected to the bottom opening of the leaching pipe, a first supporting structure is provided in the leakage trough 22, the first supporting structure is axially fixed in the leakage trough 22 and is used to support the soil sample in the leaching pipe, a number of first through holes for the passage of the leachate are evenly opened on the first supporting structure, a space for accommodating the leachate is provided between the first supporting structure and the inner bottom surface of the leakage trough 22, and the liquid outlet 25 is provided on the inner bottom surface of the leakage trough 22; a second supporting structure is provided in the leaching column 21, the second supporting structure is axially fixed in the leaching column 21 and is used to support the soil sample in the leaching column 21, a number of second through holes for the passage of the leachate are evenly opened on the second supporting structure; the first supporting structure is covered with a first filter layer, and the sampling port 211 is covered with a second filter layer. By providing a leakage trough 22 connected to the leaching pipe and disposing a first support structure within the trough 22 for supporting the soil sample within the leaching pipe, a space for accommodating the leachate is formed below the trough 22, allowing for smoother leachate outflow and preventing the soil sample from blocking the outlet 25. The first support structure is axially fixed within the trough 22, preventing axial displacement relative to the trough 22. This could prevent the soil sample from falling as a whole and altering the sampling position, potentially affecting experimental results. The second support structure is axially fixed within the leaching column 21, preventing axial displacement relative to the column 21. This ensures accurate soil sampling and prevents mixing of soil samples from different sampling depths, which could affect the sampling results. This ensures the accuracy and repeatability of experimental results. In other embodiments, the bottom surface of the trough 22 can also be sloped to facilitate leachate outflow, with the outlet 25 positioned at the lowest point of the slope to ensure complete leachate outflow. By providing a first filter layer above the first support structure and a second filter layer covering the sampling port 211, soil samples are prevented from being mixed with the extracted leachate sample, potentially affecting the experimental results. In this embodiment, the first filter layer comprises quartz sand and wire mesh, and the second filter layer comprises a 200-mesh filter. In other embodiments, the first and second filter layers may also comprise other filter materials, such as filter cotton, that allow only the leachate to pass through.

[0044] In some implementations of this embodiment, the liquid supply device further includes a rainfall device 14, which is fixedly mounted above the leaching pipe and is used to spray leachate onto the soil sample in the cavity. The provision of rainfall device 14 can better simulate rainfall in a real environment, making the experimental results more convincing.

[0045] In some embodiments of this example, the liquid supply device further includes a liquid supply tank 11 and a drive and control device. The liquid supply tank 11 is connected to a rainfall device 14 via a first pipeline 12. The drive and control device is disposed on the first pipeline 12 and is used to drive the delivery of leachate and control the delivery rate and duration of the leachate. The rainfall device 14 includes a liquid storage chamber 141 with several leakage ports evenly spaced at the bottom of the chamber 141, through which leachate can flow into the chamber. A first sensor 142 is disposed within the chamber 141 for detecting the liquid level within the chamber 141 and is signal-connected to the drive and control device. Using the drive and control device to control the leachate delivery rate and duration allows simulation of varying rainfall amounts, such as light rain, heavy rain, or drought, increasing the scalability of the experiment. In this embodiment, the drive and control device is a peristaltic pump 13, which can precisely control the leachate flow rate. In other embodiments, the drive and control device can also be a plunger pump or other device capable of regulating the leachate delivery rate. A first sensor 142 is provided within the liquid storage chamber 141 to detect the liquid level within the liquid storage chamber 141. When the liquid level reaches a set level, the flow of leachate into the rainfall device 14 is stopped. This improves the safety and stability of the leachate device and prevents the continued flow of leachate when the liquid level within the rainfall device 14 is too high, which could result in uncontrolled experimental conditions. In other embodiments, the bottom of the liquid storage chamber 141 can be designed with a detachable connection. By replacing the bottom of the liquid storage chamber 141 with different-sized leakage openings, different rainfall environments can be more accurately simulated, increasing the persuasiveness of the experimental results.

[0046] In some embodiments of this example, the liquid collection device includes a liquid collection bottle 31 and a gas suction device. The liquid collection bottle 31 has a first inlet 32 and a first outlet 33, both of which are located at the top of the liquid collection bottle 31. The first inlet 32 is connected to the liquid outlet 25, and the first outlet 33 is connected to the gas suction device. A second sensor 311 is provided in the liquid collection bottle 31 for detecting the liquid level in the liquid collection bottle 31. The second sensor 311 is signal-connected to the gas suction device. By providing the gas suction device and connecting it to the first outlet 33 of the liquid collection bottle 31, the first inlet 32 of the liquid collection bottle 31 is connected to the liquid outlet 25. By extracting gas from the liquid collection bottle 31, the leachate flowing out of the liquid outlet 25 is suctioned, thereby accelerating the leaching process and shortening the leaching cycle. The second sensor 311 is signal-connected to the gas extraction device. When the second sensor 311 detects that the liquid level in the liquid collection bottle 31 has reached a set position, extraction stops. This prevents the liquid level from rising too high, allowing the leachate to enter the gas extraction device through the first outlet 33 and damage the device. In this embodiment, the gas extraction device is a vacuum pump 34. In other embodiments, the gas extraction device can also be a compressor, fan, or other device capable of extracting gas from the liquid collection bottle 31.

[0047] In other embodiments, the rainfall device 14 and the leaching column 21, the leaching column 21 and the leaching column 21, and the leaching column 21 and the leakage trough 22 can be provided with a detachable sealed connection. The rainfall device 14 and the leaching column 21, the leaching column 21 and the leaching column 21, and the leaching column 21 and the leakage trough 22 are all provided with a detachable connection, which is convenient for adjusting the number of leaching columns 21 according to different experimental conditions to adjust the soil sample filling amount. The sealed connection is to ensure the gas suction effect of the vacuum pump 34 to ensure the leaching speed of the leachate. In this embodiment, the rainfall device 14 and the leaching column 21, the leaching column 21 and the leaching column 21, and the leakage trough 22 are connected by flange rings, which are easy to disassemble and durable. In other embodiments, the connection can also be made by other easy-to-disassemble methods such as snap fasteners.

[0048] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A leaching simulation method, characterized in that: The following steps are involved: Sample collection steps: Collect undisturbed soil samples and record soil profile information; Soil sample filling step: filling the soil layers to be tested into the leaching device in equal proportions according to the thickness of the original soil samples taken in the sample collection step, or directly filling the soil samples at specific layers, controlling the filling density to be ±5% of the original soil bulk density, to form a soil column; Comparative sample determination step: using the remaining unfilled portion of the soil layer to be tested as a comparative sample, and determining the mineralogical data and geochemical data of rare earth elements of the comparative sample; Leaching experiment steps: using the prepared leachate to leach the soil column loaded in the soil sample loading step, taking leached soil samples and leachate samples at different thicknesses of the soil column according to a preset time gradient, and collecting leachate samples flowing out from the bottom of the soil column; Post-experimental sample determination step: determining the mineralogical data and geochemical data of rare earth elements in the leached soil sample, and determining the geochemical data of rare earth elements in the leached liquid sample; The geochemical data of the rare earth elements in the comparative sample and the leached soil sample include: one or more of the content of the rare earth elements, the chemical valence of the rare earth elements, the occurrence form and the occurrence carrier of the rare earth elements.

2. The leaching simulation method according to claim 1, wherein The soil sample filling steps specifically include: Selecting a leaching device that matches the diameter of the undisturbed soil sample taken in the sample collection step; Determining the layered filling thickness of different soil layers and the distribution of different soil layers based on the thickness of the undisturbed soil sample taken in the sample collection step and the thickness and distribution order of different soil layers in the undisturbed soil sample; Accurately weigh, fill and compact the soil samples in layers.

3. The leaching simulation method according to claim 1, wherein: The mineralogical data of the comparative sample and the leached soil sample include: one or more of the types of minerals in the soil sample, the crystal structure of the minerals, and the microscopic morphology of the minerals; The geochemical data of the rare earth elements in the leachate sample include: rare earth element content, anion and cation content, pH value, redox potential, conductivity, organic acid and rare earth complex content, colloid type, and one or more of the morphology and elemental composition of the colloid.

4. The leaching simulation method according to claim 1, wherein: The leaching device comprises: A leaching body, wherein the leaching body has a cavity for holding a soil sample, a liquid inlet is provided at the top of the cavity, a liquid outlet is provided at the bottom of the cavity, and a plurality of sampling ports communicating with the interior of the cavity are provided on the sidewall of the leaching body, and the sampling ports are detachably provided with valves; a liquid supply device, the liquid supply device being in communication with the liquid inlet and being used for providing leachate to the soil sample in the cavity; and A liquid collecting device is communicated with the liquid outlet and is used to collect the leachate sample flowing out of the liquid outlet.

5. The leaching simulation method according to claim 4, wherein: The liquid inlet and the liquid outlet have a height difference in the vertical direction. The sampling port is located on the side wall of the leaching body between the liquid inlet and the liquid outlet, and a plurality of the sampling ports are provided in the vertical direction.

6. The leaching simulation method according to claim 5, characterized in that: The leaching body includes a leaching tube, which includes a plurality of leaching columns. Each of the leaching columns has a cavity with openings at both ends. The leaching columns are vertically distributed and can be sequentially connected and communicated through the openings. The connected cavities form the cavity. The sampling ports are evenly opened on the side walls of the leaching columns. The leaching body further includes a support frame, which is used to support the leaching pipe and to create a height difference between the leaching pipe and a bottom surface of the support frame.

7. The leaching simulation method according to claim 6, wherein: The leaching pipe further includes a liquid leakage trough, the top opening of the liquid leakage trough is connected to the bottom opening of the leaching pipe, a first supporting structure is provided in the liquid leakage trough, the first supporting structure is axially fixed in the liquid leakage trough and is used to support the soil sample in the leaching pipe, a plurality of first through holes for the leachate to pass through are evenly opened on the first supporting structure, a space for accommodating the leachate is provided between the first supporting structure and the bottom surface of the liquid leakage trough, and the liquid outlet is provided on the bottom surface of the liquid leakage trough; A second supporting structure is provided in the leaching column, the second supporting structure is axially fixed in the leaching column and is used to support the soil sample in the leaching column, and a plurality of second through holes for the leaching liquid to pass through are evenly opened on the second supporting structure; The first supporting structure is covered with a first filter layer, and the sampling port is covered with a second filter layer.

8. The leaching simulation method according to claim 6, wherein: The liquid supply device includes a rainfall device, which is fixedly arranged above the leaching pipe and is used to spray the leaching liquid onto the soil sample in the cavity.

9. The leaching simulation method according to claim 8, characterized in that: The liquid supply device further includes a liquid supply tank and a drive adjustment device. The liquid supply tank is connected to the rainfall device via a first pipeline. The drive adjustment device is disposed on the first pipeline and is used to drive the delivery of the leachate and control the delivery speed and time of the leachate. The rainfall device includes a liquid storage cavity, and a plurality of leakage ports are evenly arranged at the bottom of the liquid storage cavity. The leachate can flow into the cavity through the leakage ports. A first sensor is provided in the liquid storage cavity. The first sensor is used to detect the liquid level in the liquid storage cavity. The first sensor is connected to the drive adjustment device by signal.

10. The leaching simulation method according to claim 4, characterized in that: The liquid collecting device includes a liquid collecting bottle and a gas suction device, the liquid collecting bottle has a first inlet and a first outlet, the first inlet and the first outlet are both arranged at the top of the liquid collecting bottle, the first inlet is communicated with the liquid outlet, and the first outlet is communicated with the gas suction device; A second sensor is provided in the liquid collecting bottle, and the second sensor is used to detect the liquid level in the liquid collecting bottle. The second sensor is connected to the gas suction device by signal.

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