An oxidation-infiltration experimental method for simulating the process of infiltration of oxidized surface water into filler

Abstract

The present application relates to the technical field of pyrite-containing filling experimental technology, and particularly relates to an oxidation-infiltration experimental device and method for simulating the infiltration of oxidized surface water into fillings, the experimental device comprising a reaction kettle for loading samples, a water feeding device for providing infiltration solution for the samples, and a pressurizing device for constructing a controllable oxidation reaction environment for the reaction kettle, which can obtain the mineral phase change sequence and particle migration distribution characteristics of the fillings under different oxidation-infiltration coupling conditions; quantitatively analyze the dynamic correlation between the oxidation reaction rate, the infiltration speed and the composition evolution of the fillings, and further reveal the correlation mechanism between the oxidation-infiltration effect and the composition change of the fillings, thereby providing technical support for the disaster-causing mechanism analysis of the heave deformation of the pyrite-containing roadbed, and further ensuring the stability of roads and buildings.

Description

Technical Field

[0001] This invention relates to the field of experimental technology for pyrite-containing fillers, and in particular to an oxidation-seepage experimental apparatus and method for simulating the process of oxidized surface water infiltration into fillers. Background Technology

[0002] The stability and load transfer efficiency of roadbed structures are the core foundation for the safe operation of transportation engineering. With the rapid development of high-grade highways and heavy-haul railways, the engineering durability of filler materials faces more stringent requirements. Pyrite, a common by-product in natural fillers, has become a key hazard factor inducing progressive roadbed damage due to its oxidative expansion effect. Although current standards have set thresholds for pyrite content in fillers, the discreteness of mineral occurrence and insufficient resolution of detection technologies make accurate identification and risk warning of pyrite difficult to achieve in actual engineering. Under the condition of oxidizing surface water infiltration, pyrite aggregates undergo complex water-rock-gas multiphase reactions under oxidation-seepage, leading to the formation of secondary minerals and volume expansion effects, which in turn triggers the chemical-mechanical synergistic deterioration of the roadbed structure. This type of damage has long-term cumulative deformation characteristics, manifested as a continuously increasing non-convergent upward arching displacement. Its irreversibility and time-varying characteristics of expansion force significantly increase the difficulty of engineering treatment and seriously threaten the full-cycle service performance of transportation roads.

[0003] Chinese Patent (Application No. CN 106442172 A) discloses a multiphase flow-stress coupled rock core shearing experimental device and method. The device achieves good sealing of high-pressure fluid through a specially designed shear plate and soft clay, and controls the multiphase fluid using the matrix suction of a permeable baffle, making it suitable for rock mechanics experiments under complex conditions. However, the device has a complex structure and cumbersome operation, increasing production costs and quality control difficulties. Its multiphase fluid control relies on the specially designed shear plate and soft clay sealing, but the soft clay may experience reduced sealing performance due to repeated compression deformation during long-term use, affecting the accuracy of experimental data. Chinese Patent (Application No. CN 110108750 A) discloses a cross-fracture seepage heat transfer experimental device and method, capable of simulating heat source distribution and obtaining the temperature and flow field distribution over time within the specimen under different heat source distributions. However, this device has a complex structure and requires high technical skills from operators; slight improper operation may affect the accuracy of experimental data. It relies on heating pads and resistance wires to simulate heat source distribution, but this simulation method may not fully reflect the actual heat source conditions under complex geological conditions. Furthermore, the insulation layer of the device is made of silicone compound fiber insulation cotton, which may experience a decline in insulation performance due to material aging during long-term use, affecting the reliability of the experiment. Chinese Patent (CN 109342150 A) discloses an experimental apparatus and method for consolidation and permeability experiments on aerated soil samples, suitable for aerated soil experiments, improving measurement accuracy and enabling simultaneous consolidation and permeability tests. However, this apparatus is complex to operate, costly, and requires highly skilled operators, increasing the difficulty and cost of the experiment. It employs multiple sealing rings and complex piping connections; during long-term use, the sealing rings may wear down, leading to a decline in sealing performance and affecting the reliability of the experimental results. In addition, while the device's computer data processing system can improve data accuracy, it requires extremely high stability and accuracy; any malfunction could affect the entire experimental process.

[0004] Existing technologies for treating pyrite-bearing fillers face significant bottlenecks: First, some methods are complex, involving the pretreatment and modification of multiple materials, resulting in cumbersome operations, increased production costs, and greater difficulty in quality control, significantly impacting construction efficiency. Second, existing methods are sensitive to the construction environment; changes in temperature, humidity, and pH levels have a substantial impact on filler quality. Third, most current methods lack sufficient long-term performance and durability verification, requiring more practical engineering cases to demonstrate their stability and durability. These methodological deficiencies severely restrict the refined modeling of fillers in the oxidation-seepage coupling process, leaving disease prevention and control lacking theoretical and technical support. Therefore, it is urgent to construct an experimental platform capable of reproducing water-rock interactions and develop multi-parameter collaborative monitoring and cross-scale numerical simulation technologies to reveal the deterioration mechanism of pyrite-bearing fillers in dynamic seepage environments, providing a scientific basis for the durability design and intelligent maintenance of roadbed engineering, and offering theoretical support for the full life-cycle performance assurance of transportation infrastructure. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an oxidation-seepage experimental device and method for simulating the infiltration process of oxidized surface water into fillers, revealing the mineral formation sequence and particle migration characteristics of pyrite-containing fillers under different oxidation environments and seepage conditions, and further revealing the correlation mechanism between oxidation-seepage and changes in filler composition.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An oxidation-seepage experimental method for simulating the infiltration process of oxidative surface water infiltration filler is disclosed. The method uses an oxidation-seepage experimental apparatus for simulating the infiltration process of oxidative surface water infiltration filler. The experimental apparatus includes a reaction vessel, a water supply device, and a pressurization device. The bottom of the reaction vessel is connected to a drain pipe equipped with a valve. The reaction vessel has a perforated bottom plate, a sample base is placed on the bottom plate, a permeable stone is placed inside the sample base, and an acrylic cylinder is placed on top of the permeable stone.

[0008] The method includes the following steps:

[0009] S1: After the dry pyrite-containing filler sample is ground to below 150 mesh, the sample is layered and loaded into an acrylic cylinder. During the loading process, the weight moisture content and loading density of the sample are set according to the experimental requirements.

[0010] S2: Place the acrylic cylinder containing the sample on top of the permeable stone, and then place the detection device (such as temperature sensor, photoelectric displacement sensor, weight moisture content probe, etc.) as needed before closing and sealing the reaction vessel.

[0011] S3: Turn on the pressurizing device and the water adding device to keep the internal air pressure of the reactor consistent with the internal air pressure of the water adding device so that the solution in the water adding device can flow smoothly into the sample and eventually flow out from the drain pipe;

[0012] S4: By changing the type and flow rate of the solution in the water supply device and the type of gas in the pressurization device, different oxidation environments and seepage conditions are simulated. Based on Darcy's flow theory, the relationship between the permeability coefficient K of the porous medium and the pressure gradient is understood. A quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample was constructed to achieve dynamic characterization of the fluid migration rate in the pyrite reaction zone under different oxidation-seepage conditions.

[0013] Furthermore, in the method, the operation of constructing a quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample is as follows: based on the Darcy flow constitutive relation, the dynamic permeability K is calculated and the experimentally measured pressure gradient is used. Combined with the detected hydrodynamic viscosity A quantitative calculation model for the seepage rate q was constructed to understand the change in the seepage rate of the sample during the oxidation-seepage experiment, in order to characterize the changes in the internal pore structure. Specifically:

[0014] After completing the above experiments, calculate the seepage rate in the oxidation-seepage device. ,in,

[0015] Since the sample mainly consists of pyrite undergoing oxidation and acid etching, the oxidation reaction of pyrite under acidic conditions is represented as follows:

[0016] ;

[0017] The oxidation rate of pyrite was calculated based on the pyrite oxidation kinetic equation:

[0018] ;

[0019] Where r Pyrite ρ represents the oxidation rate of pyrite; M0 represents the sample mass before the experiment; M represents the sample mass after the experiment; A represents the oxidation rate of pyrite. Pyrite M represents the specific surface area of ​​pyrite. Pyrite t is the molar mass of pyrite; t is the reaction time.

[0020] Calculate the pore volume change coefficient based on the pore volume change caused by pyrite dissolution:

[0021] ;

[0022] ;

[0023] v Pyrite The pore volume change coefficient; To determine the change in pore volume before and after the reaction using nitrogen adsorption, V pore V represents the pore volume after the reaction. pore0 This represents the pore volume before the reaction. This represents the number of moles of pyrite dissolved.

[0024] Permeability K varies with porosity The variation is described by the modified Kozeny-Carman equation, porosity The changes are driven solely by the dissolution of pyrite:

[0025] ;

[0026] ;

[0027] Wherein is the initial penetration rate of K0; The initial porosity is denoted by n; n is an empirical index.

[0028] The pressure gradient ∇P of the sample before and after the reaction was indirectly calculated using Darcy's law through a gas adsorption analyzer.

[0029] ;

[0030] Where: Q is the gas flow rate of the gas adsorption analyzer; k g is the gas permeability coefficient; A is the cross-sectional area of ​​the sample.

[0031] Furthermore, the water adding device includes a hose with a distributor connected to one end and an external water tank at the other. The distributor is fixed above the sample by a movable bracket to ensure that the liquid in the water tank can enter the sample.

[0032] Furthermore, the water supply device is also equipped with a flow meter and a flow switch.

[0033] Furthermore, the water tank is equipped with a water tank pressure relief valve, a water tank pressure gauge, and a water tank pressurization device.

[0034] Furthermore, the pressurization device includes a pressure relief valve for the vessel body, a pressure gauge for the vessel body, and a gas cylinder.

[0035] Furthermore, the gas cylinder is connected to the reactor body via an air inlet, and the gas in the gas cylinder is nitrogen, oxygen, or a mixture of 50% nitrogen and 50% oxygen.

[0036] Furthermore, the reactor body is equipped with a temperature sensor and a photoelectric displacement sensor. In addition, other detection devices, including a weight moisture content probe, can be inserted into the sample for real-time detection according to actual needs. The filling material is monitored in real time by the temperature sensor, photoelectric displacement sensor and weight moisture content probe, wherein the photoelectric displacement sensor records the height of the sample in the sample.

[0037] The present invention has the following advantages and beneficial effects:

[0038] This invention provides an innovative oxidation-seepage experimental device, constructing a multi-field coupled oxidation-seepage experimental system. It innovatively integrates a hydrodynamic-chemical dynamic interaction module, effectively simulating the infiltration process of oxidizing surface water into roadbed fillers, providing a reliable experimental platform for studying pyrite-bearing roadbed fillers. The device is equipped with temperature sensors, photoelectric displacement sensors, and a weight moisture content probe, enabling real-time monitoring of the physical changes and moisture state of the fillers, thus obtaining more accurate experimental data. Through the control of gas environment and pressure, flow rate regulation, and the configuration of fluids with different pH levels, complex working conditions such as wet-dry cycles and acid rain erosion can be accurately reproduced. This allows for in-depth analysis of the mineral formation sequence and particle migration characteristics of pyrite-bearing roadbed fillers under different oxidation environments and seepage conditions, revealing the correlation mechanism between oxidation-seepage and filler composition changes. This provides important scientific basis for the design and construction of railway roadbeds, improving railway safety and durability. The experimental method and device design are highly adaptable, able to be adjusted according to different research needs, and suitable for research on various types of fillers and seepage conditions. Furthermore, this invention provides theoretical support and experimental basis for solving the problems of arching deformation and defects of fill material in high-speed railway construction, has important practical application value, and promotes the application of environmentally friendly materials in railway engineering, which is in line with the concept of sustainable development. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the oxidation-seepage experimental device for simulating the infiltration process of oxidized surface water into the filler material in an embodiment of the present invention.

[0040] Figure 2 This is a top view of the reactor of the oxidation-seepage experimental device used in an embodiment of the present invention to simulate the process of oxidizing surface water infiltration into the filler.

[0041] Figure 3 This is a top view of the sample base of the oxidation-seepage experimental device used in the embodiment of the invention to simulate the process of oxidized surface water infiltration into the filler.

[0042] Reference numerals: 1-Reaction vessel body, 2-Vessel handle, 3-Hose, 4-Modible support, 5-Perforated base plate, 6-Drain pipe, 7-Sample base, 8-Permeable stone, 9-Acrylic cylinder, 10-Sensor mounting position, 11-Diverter, 12-Vessel pressure relief valve, 13-Vessel pressure gauge, 14-Vessel air inlet, 15-Gas cylinder, 16-Temperature sensor, 17-Photoelectric displacement sensor, 18-Weight moisture content probe, 19-Flow meter, 20-Flow switch, 21-Water tank pressure relief valve, 22-Water tank pressure gauge, 23-Water tank pressurization device, 24-Sample, 25-Water tank. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0044] like Figure 1 As shown, an oxidation-seepage experimental apparatus for simulating the infiltration process of oxidizing surface water into filler material includes a reaction vessel, a water supply device, and a pressurization device. The reaction vessel is the main container used to encapsulate pyrite-containing filler material samples and implement water-rock reactions. The water supply device provides seepage solution to the samples inside the reaction vessel, and the pressurization device provides a reaction gas environment for the reaction vessel. In this embodiment, the dimensions of the reaction vessel body 1 are set as follows: Internal dimensions design of acrylic tube 9 The dimensions of sample 24 are as follows: To reduce the influence of size effect on the experiment, the dried pyrite-containing filler sample 24 was ground to below 150 mesh using a grinder. A certain amount of distilled water was added to the ground sample 24 to simulate the weight water content Wg of the sample 24 under real conditions. The sample 24 was then filled into the acrylic cylinder 9 according to a certain density ρ.

[0045] The reaction vessel includes a handle 2 and a vessel body 1. The bottom of the vessel body 1 has a downwardly concave arc to guide the solution flow to a drain pipe 6 equipped with a valve. The vessel body 1 has a perforated bottom plate 5, on which six sample bases 7 are evenly placed. A permeable stone 8 is placed inside the sample base 7, and an acrylic cylinder 9 containing the sample is placed on top of the permeable stone 8. To achieve the detection of relevant indicators, the experimental device in this embodiment also includes a temperature sensor 16, a photoelectric displacement sensor 17, and a weight moisture content probe 18. The temperature sensor 16 and the photoelectric displacement sensor 17 are installed on sensor fixing positions 10 inside the vessel body 1, respectively, for real-time monitoring of temperature and height changes during the sample reaction process. The weight moisture content probe 18 is inserted into the sample, and by real-time monitoring of the weight moisture content change of the sample, the water inlet is adjusted to stabilize the weight moisture content of the sample within the range required for the experiment.

[0046] The water supply device includes a flexible hose 3, with its two ends connected to a distributor 11 and an external water tank 25, respectively. The distributor 11 is fixed above the sample 24 by a movable bracket 4 to ensure that the liquid in the water tank 25 can enter the sample. The water tank 25 is equipped with a water tank pressure relief valve 21, a water tank pressure gauge 22, and a water tank pressurization device 23. A flow meter 19 and a flow switch 20 are installed at the connection between the water tank 25 and the vessel body 1 to control and monitor the flow rate of the solution.

[0047] The pressurization device includes a pressure relief valve 12, a pressure gauge 13, and a gas cylinder 15. The gas cylinder 15 can be a nitrogen cylinder, an oxygen cylinder, or a mixed gas cylinder, depending on the experimental requirements. The oxygen cylinder contains pure oxygen, the nitrogen cylinder contains pure nitrogen, and the mixed gas cylinder contains 50% nitrogen and 50% oxygen. The gas cylinder is connected to the reactor body 1 through an air inlet 14.

[0048] In this invention, when collecting liquid and filler samples, the pressure in the vessel 1 and water tank 25 must be released first to ensure safety during the experiment. Then, the aforementioned device is used to conduct pre- and post-etching mineral composition testing and chemical composition analysis on the collected samples, specifically as follows:

[0049] A method for conducting experiments using the aforementioned oxidation-seepage experimental apparatus that simulates the infiltration process of oxidative surface water includes the following steps:

[0050] S1: To reduce the influence of size effect on the experiment, the dried pyrite-containing filler sample was ground to below 150 mesh using a grinder, and the sample mass was recorded as M0. A certain amount of distilled water was added to the ground sample to simulate the weight moisture content W of sample 24 under real conditions. g Then, according to a certain density ρ, the sample is placed into the acrylic cylinder 9 in 5 layers, with roughening treatment between layers. The filling is uniformly compacted, and the weight moisture content W is... g The formula for calculating density ρ is as follows:

[0051] ;

[0052] ;

[0053] Among them: W g G represents the moisture content by weight of the sample. W G represents the amount of distilled water added. S ρ is the weight of the dried sample, ρ is the density of the sample 24 inside the acrylic cylinder 9, m is the weight of the sample, and v is the volume of the sample.

[0054] S2: Place the acrylic cylinder 9 containing the sample above the permeable stone 8, then insert the weight moisture content probe 18 into the sample 24, and close and seal the reactor body 1.

[0055] S3: Open the gas cylinder 15, the gas inlet 14 of the vessel, the flow switch 20, the water tank pressurization device 23, and the drain pipe 6 with a valve. At the same time, observe the pressure gauge 13 of the vessel and the pressure gauge 22 of the water tank to keep the internal pressure of the vessel consistent with the internal pressure of the water tank so that the solution in the water tank 25 can flow smoothly into the sample 24 and finally flow out from the drain pipe 6 with a valve.

[0056] S4: The flow rate of the solution in the water tank 25 through the sample is controlled by adjusting the flow switch. Different gas environments are set by changing the gas cylinder 15, including 100% oxygen cylinder, 100% nitrogen cylinder and 50% oxygen + 50% nitrogen cylinder. Multiple sets of parallel experiments are conducted to analyze the mineral formation sequence and particle migration characteristics of pyrite filler under different oxidation environments and seepage conditions, and to reveal the correlation mechanism between oxidation-seepage and filler composition changes.

[0057] S5: The packing material is monitored in real time using temperature sensor 16, photoelectric displacement sensor 17, and weight moisture content probe 18. Since temperature significantly affects the expansion rate and fluid dynamic viscosity, temperature sensor 16 is used to monitor the temperature in real time. Photoelectric displacement sensor 17 records the packing height during the experiment to observe changes in the expansion rate. The expansion rate δ of the packing material is calculated from the initial height H0 of sample 24 before reaction and the packing height H after reaction.

[0058] ;

[0059] The pore volume V of sample 24 before and after the reaction was measured using a gas adsorption analyzer via nitrogen adsorption. pore0 and V pore Simultaneously, the pressure gradient of sample 24 before and after the reaction was indirectly calculated using Darcy's law through a gas adsorption analyzer. ;

[0060] ;

[0061] ;

[0062] in: V represents the change in pore volume before and after the reaction. pore V represents the pore volume after the reaction. pore0 The pore volume before the reaction is given; Q is the gas flow rate of the gas adsorption analyzer; k g is the gas permeability coefficient; A is the cross-sectional area of ​​the soil and rock sample;

[0063] S6: During the first 7 days of the experiment, water quality analysis of the reaction solution is performed at 1-day intervals, including tests for pH, conductivity, and major element ion concentration. During the later stages of the experiment, water quality analysis is also performed at 7-day intervals. Simultaneously, at different reaction stages (e.g., every month), the pressure relief valve 12 of the reactor body and the pressure relief valve 21 of the water tank are used to depressurize the reactor body and water tank. The reactor body handle 2 is lifted, and a portion of the filler material from one of the sample 24 is removed from the reactor. The mineral composition and chemical composition of the filler material are tested before and after erosion. The sample 24 is then dried and its mass M is measured.

[0064] S7: After completing the above experiment, in order to calculate the seepage rate q in the oxidation-seepage device, since the sample 24 in the device is mainly composed of pyrite undergoing oxidation and acid etching, the oxidation reaction of pyrite under acidic conditions can be expressed as:

[0065] ;

[0066] The oxidation rate of pyrite was calculated based on the pyrite oxidation kinetic equation:

[0067] ;

[0068] Where r Pyrite M represents the oxidation rate of pyrite; M0 represents the mass of sample 24 before the experiment; M represents the mass of sample 24 after the experiment; A Pyrite The specific surface area of ​​pyrite is calculated using the BET formula based on adsorption isotherm data; M Pyrite t is the molar mass of pyrite; t is the reaction time.

[0069] Calculate the pore volume change coefficient based on the pore volume change caused by pyrite dissolution:

[0070] ;

[0071] ;

[0072] v Pyrite The pore volume change coefficient; To determine the change in pore volume before and after the reaction using nitrogen adsorption method; This represents the number of moles of pyrite dissolved.

[0073] Permeability K varies with porosity The variation is described by the modified Kozeny-Carman equation, porosity The changes are driven solely by the dissolution of pyrite:

[0074] ;

[0075] ;

[0076] Wherein is the initial penetration rate of K0; The initial porosity is denoted by n; n is an empirical index.

[0077] Based on the Darcy constitutive relation, a quantitative calculation model for the seepage rate q is constructed by combining the calculated dynamic permeability K with the experimentally measured pressure gradient ∇P and the fluid dynamic viscosity μ (measured by a rotational viscometer). This model helps to understand the change in the seepage rate of the sample during the oxidation-seepage experiment, and thus characterizes the changes in the internal pore structure.

[0078] .

[0079] The following example is an oxidation-percolation experiment.

[0080] This experiment aims to study the changes in the physicochemical properties of the packing material under specific conditions, particularly its behavior during the seepage process. The dry density of the packing material was set to 1.45 g / cm³. 3 The weight moisture content was set to 5%, and distilled water was used as the experimental fluid. A temperature sensor was used to monitor the temperature inside the reactor in real time. The rock sample mass was weighed using a balance before and after the experiment, and the pore volume of the rock sample was measured using a gas adsorption analyzer. Basic data for the rock sample and fluid are shown in Table 1.

[0081] Table 1. Basic data of rock samples and fluids

[0082]

[0083] The simulation experiment was conducted according to the above method, and the experimental data was systematically analyzed and processed to obtain the final calculation results. The detailed data are listed in Table 2 and Table 3 respectively.

[0084] Table 2 Test Results

[0085]

[0086] Table 3 Calculation Results

[0087]

[0088] Based on the above tests and calculations, the expansion rate δ and seepage rate q of this rock sample can be obtained as shown in Table 4.

[0089] Table 4. Swelling rate δ and seepage rate q of rock samples

[0090]

[0091] The detection and calculation results in this experiment only cover the initial stage of the oxidation-percolation experiment. To fully understand the dynamic changes of the sample during the oxidation-percolation process, subsequent experiments should perform detection and calculation at different reaction stages and record the changes in the expansion rate δ and percolation rate q, thereby effectively characterizing the evolution of the internal pore structure of the sample. This process is of great significance for a deeper understanding of the oxidation-percolation mechanism.

[0092] The above descriptions are merely embodiments of the present invention, and common technical solutions or characteristics known in the schemes are not described in detail here. For those skilled in the art, various modifications and improvements can be made without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An oxidation-seepage experimental method for simulating the process of oxidizing surface water infiltration filler, the method using an oxidation-seepage experimental apparatus for simulating the process of oxidizing surface water infiltration filler, the apparatus comprising a reaction vessel, a water supply device for providing seepage solution to the sample, and a pressurization device for constructing a controllable oxidation reaction environment for the reaction vessel, the reaction vessel comprising a vessel body and an outlet with a downwardly concave arc at the bottom of the vessel body to guide the flow of the solution; the reaction vessel body has a perforated bottom plate, a sample base is placed on the bottom plate, a permeable stone is placed inside the sample base, and an acrylic cylinder is placed on top of the permeable stone. The method includes the following steps: S1: After the dry pyrite-containing filler sample is ground to below 150 mesh, the sample is layered and loaded into an acrylic cylinder. During the loading process, the weight moisture content and loading density of the sample are set according to the experimental requirements. S2: Place the acrylic cylinder containing the sample on top of the permeable stone, place the testing device as needed, and then close and seal the reactor body. S3: Turn on the pressurizing device and the water adding device to keep the air pressure inside the vessel consistent with the air pressure inside the water adding device, so that the solution in the water adding device can flow smoothly into the sample and finally flow out from the outlet. S4: By changing the type and flow rate of the solution in the water addition device and the type of gas in the pressurization device, different oxidation environments and seepage conditions are simulated. Based on Darcy's seepage theory, by mastering the permeability coefficient K of the porous medium and the pressure gradient ∇P, a quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample is constructed, so as to realize the dynamic characterization of the fluid migration rate in the pyrite reaction zone under different oxidation-seepage conditions. In the method described above, the operation of constructing a quantitative relationship between the seepage rate q and the internal pore structure parameters of the sample is as follows: Based on the Darcy flow constitutive relation, by calculating the dynamic permeability K and experimentally measured pressure gradient ∇P, and combining the detected hydrodynamic viscosity μ, a quantitative calculation model for the seepage rate q is constructed to understand the change in the seepage rate of the sample in the oxidation-seepage experiment, which is used to characterize the change in the internal pore structure. Specifically: After completing the experiment, calculate the seepage rate in the oxidation-seepage device. ,in, Since the sample mainly consists of pyrite undergoing oxidation and acid etching, the oxidation reaction of pyrite under acidic conditions is represented as follows: ； The oxidation rate of pyrite was calculated based on the pyrite oxidation kinetic equation: ； Where r Pyrite ρ represents the oxidation rate of pyrite; M0 represents the sample mass before the experiment; M represents the sample mass after the experiment; A represents the oxidation rate of pyrite. Pyrite M represents the specific surface area of ​​pyrite. Pyrite t is the molar mass of pyrite; t is the reaction time. Calculate the pore volume change coefficient based on the pore volume change caused by pyrite dissolution: ； ； v Pyrite ΔV is the pore volume change coefficient. pore To determine the change in pore volume before and after the reaction using nitrogen adsorption, V pore V represents the pore volume after the reaction. pore0 Δn represents the pore volume before the reaction. Pyrite This represents the number of moles of pyrite dissolved. The variation of permeability K with porosity ϕ is described by a modified Kozeny-Carman equation, where the variation in porosity ϕ is driven solely by pyrite dissolution: ； ； Where K0 is the initial permeability; ϕ0 is the initial porosity; and n is the empirical index. The pressure gradient ∇P of the sample before and after the reaction was indirectly calculated using Darcy's law through a gas adsorption analyzer. ； Where: Q is the gas flow rate of the gas adsorption analyzer; k g is the gas permeability coefficient; A is the cross-sectional area of ​​the sample.

2. The method according to claim 1, characterized in that, The detection device includes a temperature sensor and a photoelectric displacement sensor placed inside the vessel for real-time monitoring of temperature and height changes, respectively, as well as a weight moisture content probe for detecting the weight moisture content of the sample.

3. The method according to claim 1, characterized in that, The water supply device includes a hose with a distributor connected to one end and an external water tank at the other. The distributor is fixed above the sample by a movable bracket to ensure that liquid in the water tank can enter the sample; and / or The water supply device is also equipped with a flow meter and a flow switch; and / or The water tank is equipped with a water tank pressure relief valve, a water tank pressure gauge, and a water tank pressurization device; and / or The pressurization device includes a pressure relief valve for the vessel body, a pressure gauge for the vessel body, and a gas cylinder; and / or The gas cylinder is connected to the reactor body through an air inlet, and the gas in the gas cylinder is nitrogen, oxygen, or a mixture of 50% nitrogen and 50% oxygen.

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