A method for in-situ leaching of ore with variable mesh

Abstract

This invention discloses an in-situ leaching method with variable mesh density injection. Based on mine exploration results, the method obtains the grade distribution data of valuable elements in ion-adsorption rare earth mines. It then arranges the injection and collection processes for the ion-adsorption rare earth mine according to the in-situ leaching process. The mine undergoes sparse injection; the flow rate and concentration of valuable elements in the collected leaching solution are measured; the relationship between the concentration of valuable elements in the leaching solution and the ore body mass, leaching agent volume, valuable element grade, and initial leaching agent concentration are established; the average grade of valuable elements in the overlying ore body, the average flow rate of the leaching solution, and the average concentration of valuable elements in the leaching solution are calculated for each control area of ​​the collection process; the average flow rate and the average concentration of valuable elements collected by the collection process are compared with the actual values, and adjustments are made based on the comparison results. This method can effectively control the injection process, improve the leaching rate of valuable elements, and reduce the risk of landslides.

Description

Technical Field

[0001] This invention relates to the field of in-situ leaching technology, and in particular to an in-situ leaching method using variable mesh size injection. Background Technology

[0002] Ion-adsorption rare earth minerals are a major source of medium and heavy rare earth elements and have significant industrial application value. Currently, the main mining process for ion-adsorption rare earth minerals is in-situ leaching. In-situ leaching can be simply described as follows: injection holes are excavated on the mine surface, and a leaching agent solution is injected into these holes. The leaching agent penetrates into the ore body and reacts with rare earth ions, which are then exchanged and migrate with the solution. The leaching mother liquor containing rare earth ions is collected in a collection system and then transported to a hydrometallurgical workshop for post-processing. The rational layout of the injection system affects the efficiency of the leaching agent, the rare earth leaching rate, the rare earth concentration in the leaching mother liquor, and the safety and stability of the ore body slope, making it a crucial aspect of the in-situ leaching process.

[0003] In existing technologies, the design of injection orifice parameters and the control of injection intensity in ion-adsorption rare earth in-situ leaching are typically based on the experience of mine operators, lacking theoretical and technical guidance. Some scholars have conducted research on the design of injection orifice parameters and the control of injection intensity, offering many instructive suggestions. However, due to the differences in topography, geological conditions, and spatial variability of ore bodies in ion-adsorption rare earth mines, the relevant research results are difficult to widely apply. In the process of ion-adsorption rare earth in-situ leaching, once the injection and recovery processes are completed, according to current experience, the mine generally does not optimize or adjust these processes after full injection. When the ore body permeability and the rare earth concentration in the leaching mother liquor are not as expected, intervention can only be achieved by controlling the injection intensity. It is impossible to implement multi-pronged control measures based on the ore body permeability and rare earth leaching conditions, leading to a series of problems such as large leaching blind zones, low rare earth leaching rates, large amounts of leaching agents, and frequent geological disasters. Summary of the Invention

[0004] The purpose of this invention is to provide an in-situ leaching method with variable mesh size injection. This method addresses the problems of large leaching blind zones, low leaching rates of valuable elements, large amounts of leaching agent, and frequent geological disasters such as landslides caused by unreasonable design of injection mesh parameters and improper control of injection intensity in in-situ leaching. It effectively regulates the injection process, improves the leaching rate of valuable elements, and reduces the risk of landslides.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for in-situ leaching of ore using variable mesh size injection, the method comprising:

[0007] Step 1: Obtain the grade distribution data of valuable elements in ion-adsorption rare earth mines based on the results of mine exploration, and delineate the valuable element ore bodies;

[0008] Step 2: Arrange the injection and recovery works of the ion-adsorption rare earth mine according to the in-situ leaching process;

[0009] Step 3: Select a portion of the injection holes from the arranged injection holes to perform sparse injection in the mine. The selected injection hole mesh size is larger than the designed minimum injection hole mesh size. After injection, collect the leachate according to the arranged collection project.

[0010] Step 4: Measure the flow rate and concentration of valuable elements of the leachate collected by the liquid collection process;

[0011] Step 5: Establish the relationship between the concentration of valuable elements in the leaching solution and the ore body mass, leaching agent volume, valuable element grade, and initial concentration of leaching agent;

[0012] Step 6: Calculate the average grade of valuable elements in the overlying ore body, the average flow rate of the leachate, and the average concentration of valuable elements in the leachate in each controlled area of ​​the leaching project.

[0013] Step 7: Compare the average flow rate and actual value of the leachate collected by the liquid collection project with the average concentration of valuable elements and the actual value. Based on the comparison results, adjust the in-situ leaching injection network, injection intensity and leaching agent concentration.

[0014] As can be seen from the technical solution provided by the present invention, the above method effectively regulates the injection process, improves the leaching rate of valuable elements, and reduces the risk of landslides caused by unreasonable design of injection hole parameters and improper control of injection intensity in in-situ leaching. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the in-situ leaching method with variable mesh size injection provided in an embodiment of the present invention;

[0017] Figure 2 This is a front view of an ion-type rare earth in-situ leaching ore with a flow guide hole for liquid collection, as illustrated in the example of this invention.

[0018] Figure 3The above is a front view of an ion-type rare earth in-situ leaching process using a liquid collection tunnel, as an example of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments, and do not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0020] like Figure 1 The diagram shown is a schematic flow chart of an in-situ leaching method with variable mesh size injection provided in an embodiment of the present invention. The method includes:

[0021] Step 1: Obtain the grade distribution data of valuable elements in ion-adsorption rare earth mines based on the results of mine exploration, and delineate the valuable element ore bodies;

[0022] Step 2: Arrange the injection and recovery works of the ion-adsorption rare earth mine according to the in-situ leaching process;

[0023] In this step, injection holes are arranged on the overburden of the ore body according to certain hole network parameters, and injection pipes are arranged between the injection holes to transport the leaching agent in the high-level pool to each injection hole through the injection pipes; a water tap is installed above the injection hole to control the injection intensity; and a liquid collection project is arranged at the bottom of the ore body to intercept or guide the leaching liquid.

[0024] The injection holes are arranged in a quincunx pattern, with a row spacing of 2m × row spacing of 2m between adjacent injection holes, a hole diameter of 0.1 to 0.18m, and a hole depth of 0.5 to 1m when ore is encountered.

[0025] For mines with natural liquid collection bottom plates, liquid collection projects consisting of diversion holes and collection ditches are arranged. Both the collection ditches and diversion holes are located at the foot of the mountain. The diversion holes are excavated vertically upwards at an inclination of 3‰ to 5‰.

[0026] For mines without a natural liquid collection floor, a liquid collection project consisting of diversion holes, liquid collection roadways, and liquid collection ditches is implemented. The diversion holes are located on both sides of the liquid collection roadway, while the liquid collection ditches and roadways are located at the foot of the mountain. The liquid collection roadways run parallel to the mountain's orientation, with adjacent liquid collection roadways spaced 15–20 meters apart. The bottom surface of the liquid collection roadways maintains a slope of 3‰–5‰, cutting downwards from the inside out.

[0027] Step 3: Select a portion of the injection holes from the arranged injection holes to perform sparse injection in the mine. The selected injection hole mesh size is larger than the designed minimum injection hole mesh size. After injection, collect the leachate according to the arranged collection project.

[0028] Step 4: Measure the flow rate and concentration of valuable elements of the leachate collected by the liquid collection process;

[0029] In this step, for mines with natural liquid collection bottom plates, the liquid collection process is measured at fixed times and locations every day, namely the flow rate of leachate at the outlet of each guide hole and the confluence of the liquid collection ditch, and the concentration of valuable elements in the leachate is detected.

[0030] For mines without a natural liquid collection base, the liquid collection process is measured at fixed times and locations every day, namely the flow rate of leachate at each guide hole, the outlet of the liquid collection roadway, and the confluence of the liquid collection ditch, and the concentration of valuable elements in the leachate is detected.

[0031] Step 5: Establish the relationship between the concentration of valuable elements in the leaching solution and the ore body mass, leaching agent volume, valuable element grade, and initial concentration of leaching agent;

[0032] In this step, the relationship is established based on the Kerr model describing the ion exchange selectivity coefficient, which is expressed as:

[0033]

[0034] In the formula, K is the selection coefficient of the Kerr model; [N n+ ] and [M m+ [ ] represent the molar concentrations of cations and valuable elements in the liquid phase leaching agent, respectively, in mol / L; [NX n ] and [MX m [] represents the molar concentration of cations and valuable elements in the solid phase leaching agent, respectively, in mol / g;

[0035] Initially, there are no valuable elements in the liquid phase and no adsorbed leaching agent cations on the solid phase. According to the equivalence principle, after ion exchange equilibrium, the relationship between the number of moles of leaching agent cations in the solid phase and the number of moles of valuable elements in the liquid phase is as follows:

[0036] mm s [NX n ]=nV L [M m+ (2)

[0037] In the formula, m s The mass of the rare earth mineral sample is expressed in g; V L Let L be the volume of the solution.

[0038] Before and after the ion exchange reaction, the mass conservation of both leaching agent cations and valuable elements in the system should be satisfied. After ion exchange equilibrium, the sum of the molar number of leaching agent cations in the liquid phase and the molar number of leaching agent cations in the solid phase is equal to the molar number of leaching agent cations in the liquid phase before the ion exchange. Therefore:

[0039] [N n+ VL +[NX n ]m s =[N n+ ]0V L (3)

[0040] In the formula, [N n+ [0] represents the molar concentration of cations in the liquid leaching agent before leaching, in mol / L;

[0041] Similarly, if the sum of the number of moles of valuable elements in the liquid phase and the number of moles of valuable elements in the solid phase equals the number of moles of valuable elements in the solid phase before ion exchange, then:

[0042] [M m+ V L +[MX m ]m s =[MX m ]0m s (4)

[0043] In the formula, [MX m [0] represents the molar concentration of valuable elements in the solid phase before ion exchange, in mol / g;

[0044] By rearranging equations (2) to (4), and expressing the molar concentrations of solid-phase leaching agent cations, liquid-phase leaching agent cations, and solid-phase valuable elements in terms of liquid-phase valuable element molar concentrations, we have:

[0045]

[0046]

[0047]

[0048] Substituting equations (5) to (6) into equation (1), and using the concentration of valuable elements in the liquid phase to represent the selection coefficient K of the Kerr model, then:

[0049]

[0050] Molar concentration of valuable elements in the solid phase before ion exchange [MX] m ]0 is represented as:

[0051]

[0052] In the formula, α represents the grade of the valuable element, in g / g; M RE This represents the relative molar mass of a valuable element, expressed in g / mol.

[0053] Substituting equation (9) into equation (8), we obtain the expression for the Kerr model selection coefficient K, which includes the concentration of valuable elements in the liquid phase, the rare earth grade, and the initial concentration of the leaching agent:

[0054]

[0055] If the selection coefficient K is considered a constant, then the concentration of valuable elements in the liquid phase after the reaction reaches equilibrium is inversely proportional to the volume of the leaching agent, and directly proportional to the ore body quality, the grade of valuable elements, and the initial concentration of the leaching agent.

[0056] Step 6: Calculate the average grade of valuable elements in the overlying ore body, the average flow rate of the leachate, and the average concentration of valuable elements in the leachate in each controlled area of ​​the leaching project.

[0057] In this step, for mines with a natural liquid collection floor, the liquid collection engineering control area is defined by the diversion holes; for mines without a natural liquid collection floor, the liquid collection engineering control area is defined by the liquid collection roadways. The average grade of valuable elements in the overlying ore body of each liquid collection engineering control area is then calculated using the following formula:

[0058]

[0059] In the formula, α a Indicates the average grade of valuable elements in the overlying ore body of the liquid recovery project; α i and m i These represent the valuable element grade and ore body quality of the overlying ore body in the i-th liquid collection engineering control area, respectively.

[0060] The average flow rate of each liquid collection control area is calculated using the following formula:

[0061]

[0062] In the formula, Q a Q represents the average flow rate within the controlled area of ​​the liquid collection process; T N represents the total flow rate at the confluence of leachate in each controlled area of ​​the liquid collection project; N represents the total number of controlled areas of the liquid collection project.

[0063] According to Darcy's law, the actual flow rate of the i-th liquid collection engineering control area is expressed as:

[0064]

[0065] In the formula, Q i Let F be the actual flow rate in the control area of ​​the i-th liquid collection project; h be the cross-sectional area of ​​the water flow; L be the total head loss; I = h / L be the hydraulic gradient; k (lowercase) be the permeability coefficient; the actual flow rate in the control area of ​​the i-th liquid collection project is positively correlated with the permeability coefficient, cross-sectional area of ​​the water flow, and hydraulic gradient of the ore body in that area.

[0066] The average concentration of valuable elements in the leachate from each controlled area of ​​the leachate collection project is calculated using the following formula:

[0067]

[0068] In the formula, c a This indicates the average concentration of valuable elements in the leachate collected by the leachate collection process; c i Q i Let represent the concentration of valuable elements in the leachate collected by the i-th leachate collection project and the leachate flow rate, respectively.

[0069] Step 7: Compare the average flow rate and actual value of the leachate collected by the liquid collection project with the average concentration of valuable elements and the actual value. Based on the comparison results, adjust the in-situ leaching injection network, injection intensity and leaching agent concentration.

[0070] In this step, the specific control process is as follows:

[0071] If α i <α a Q i a c i <c a If , it means that the grade of valuable elements in the i-th liquid collection engineering control area is low, the flow rate of the leachate is small, and the concentration of valuable elements in the leachate is low. In this case, the liquid injection network should be densified.

[0072] If α i <α a Q i a c i >c a If the value of the elements is low, the leachate flow rate is small, and the concentration of valuable elements in the leachate is high in the i-th liquid collection control area, then the injection intensity should be increased.

[0073] If α i <α a Q i Q a c i <c a If the value of the elements is low in the i-th liquid collection control area, the leachate flow rate is high, and the concentration of valuable elements in the leachate is low, then the liquid injection network should be expanded and the liquid injection intensity reduced.

[0074] If α i <α a Q i Q a c i >c a If , it means that the valuable element grade is low, the leachate flow rate is large, and the valuable element concentration in the leachate is high in the i-th liquid collection engineering control area, and no adjustment is required.

[0075] If α i >α a Q​​i a c i <c a If the value of the elements is high in the i-th liquid collection control area, the leaching liquid flow rate is low, and the concentration of valuable elements in the leaching liquid is low, then the injection network density should be increased and the concentration of leaching agent should be increased.

[0076] If α i >α a Q i a c i >c a If the value of the elements is high in the i-th liquid collection control area, the leachate flow rate is low, and the concentration of valuable elements in the leachate is high, then the injection network density should be increased and the injection intensity should be increased.

[0077] If α i >α a Q i Q a c i <c a If , it means that the grade of valuable elements in the i-th liquid collection engineering control area is high, the flow rate of the leachate is high, and the concentration of valuable elements in the leachate is low. At this time, the injection intensity should be reduced, the injection network density should be increased, and the concentration of leaching agent should be increased.

[0078] If α i >α a Q i Q a c i >c a This indicates that the i-th liquid collection engineering control area has a high grade of valuable elements, a high flow rate of leachate, and a high concentration of valuable elements in the leachate. In this case, the liquid injection network should be densified.

[0079] It is worth noting that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0080] The method described in the embodiments of the present invention will be explained in detail below with specific examples:

[0081] Example 1: This example 1 applies to ion-adsorption rare earth mines with natural liquid-collecting bottom plates, such as... Figure 2 The image shown is a front view of an ion-type rare earth in-situ leaching process using a flow guide hole, as described in the example of this invention. Figure 2 The system includes: 1. Ore body; 2. Injection hole; 3. Injection pipeline; 4. High-level pool; 5. Non-ore zone; 6. Bedrock; 7. Collection ditch; 8. Diversion hole; 9. Injection zone 1; 10. Injection zone 2; 11. Injection zone 3; 12. Injection zone 4; 13. Injection zone 5. The specific process is as follows:

[0082] ​​(1) Obtain data on the distribution of ion-adsorption rare earth grades in ion-adsorption rare earth mines. Based on the exploration results of ion-adsorption rare earth mines, calculate the ion-adsorption rare earth grades at different locations in the mines and delineate the ion-adsorption rare earth ore body 1.

[0083] (2) Injection holes 2 are arranged on the overburden of the ion-adsorption rare earth ore body 1. The injection holes 2 are arranged in a "plum blossom" shape, with a row spacing × row spacing of 2m × 2m and a hole diameter of 0.1m. Injection pipes 3 are arranged between the injection holes 2 to transport the leaching agent (6wt% magnesium sulfate heptahydrate solution) in the high-level pool 4 to each injection hole 2. Water taps are installed above the injection holes 2 to control the injection intensity (initial injection intensity controlled at 0.8m). 3 / d). At the bottom of the ore body 1 and the upper part of the bedrock 6, the non-ore zone 3 is arranged along the foot of the ion-type rare earth mine with a collection ditch 7 and a diversion hole 8. The diversion hole 8 is excavated vertically upwards to divert the leachate.

[0084] (3) The test ore block was divided into five injection zones at equal intervals along the foot of the mountain, namely injection zone 1 (9), injection zone 2 (10), injection zone 3 (11), injection zone 4 (12), and injection zone 5 (13), with an interval of 20m between adjacent injection zones. The corresponding collection ditch for each injection zone was used for segmented collection of leachate, and the leachate from the five zones eventually converged at one end of the collection ditch.

[0085] (4) Calculate the average rare earth grade of the ore body in each injection zone:

[0086]

[0087] In the formula, α a Indicates the average rare earth grade of the ore bodies in the five injection zones; α i and m i Let represent the average rare earth grade and ore body mass of injection zone i, respectively; where α1 = 0.39, α2 = 0.63, α3 = 0.94, α4 = 0.58, α5 = 0.32, m1 = 3455t, m2 = 4493t, m3 = 5072t, m4 = 4680t, m5 = 3396t, and α is calculated to be... a =0.60.

[0088] (5) Select some of the injection holes in the arranged injection holes 2 for injection. The selected injection holes are in the shape of "plum blossom". The row spacing of adjacent injection holes is 4m × row spacing = 4m.

[0089] (6) When the liquid begins to flow out of the guide hole, measure the flow rate of the leachate in the collection ditch of each injection section and the concentration of rare earth ions therein, as well as the flow rate and the concentration of rare earth ions therein at the confluence of the leachates in the 5 injection sections.

[0090] (7) Calculate the average flow rate of leachate in each injection zone:

[0091]

[0092] In the formula, Q a Q represents the average flow rate across the five injection zones. i This represents the leachate flow rate in the collection ditch of injection section i. After 30 days of injection, Q1 = 52 m³ / s. 3 / d、Q2=37m 3 / d、Q3=45m 3 / d、Q4=57m 3 / d、Q5=49m 3 / d, calculate Q a =48m 3 / d.

[0093] (8) Calculate the average concentration of rare earth ions in the leachate of each injection zone:

[0094]

[0095] In the formula, c a c represents the average concentration of rare earth ions at the confluence of the leachates from the five injection zones. i This represents the rare earth ion concentration in the leachate collection ditch of injection section i. After 30 days of injection, c1 = 0.34 g / L, c2 = 0.66 g / L, c3 = 0.53 g / L, c4 = 0.59 g / L, and c5 = 0.41 g / L. The calculated c... a =0.50g / L.

[0096] (9) By comparing the leachate flow rate and rare earth ion concentration in the collection ditch of each injection section with the average leachate flow rate and rare earth ion concentration of the five injection sections, the in-situ leaching injection network density, injection intensity, and leaching agent concentration were adjusted. Specifically:

[0097] For injection zone 1: α1 < α a Q1 > Q a c1 < c a This indicates that the rare earth grade of the ore body in this area is low, the leaching solution flow rate is large, and the rare earth ion concentration in the leaching solution is low. Therefore, the injection grid size should be increased to 6m × 6m, and the injection intensity reduced to 0.5m. 3 / d.

[0098] For injection zone 2: α2>α a Q2 > Q a c2 > c a This indicates that the rare earth grade of the ore body in this area is relatively high, the leaching flow rate is relatively large, and the rare earth ion concentration in the leaching solution is relatively high. At this time, the injection mesh density is increased to 4m×4m.

[0099] For injection zone 3: α3 > α a Q3 < Q a c3 > c a This indicates that the rare earth grade of the ore body in this area is relatively high, the leaching solution flow rate is relatively low, and the rare earth ion concentration in the leaching solution is relatively high. At this time, the injection mesh density is increased to 4m×4m, and the injection intensity is increased to 1m. 3 / d.

[0100] For injection zone 4: α4 < α a Q4 > Q a c4 > c a This indicates that the rare earth grade of the ore body in this area is low, the leaching solution flow rate is large, and the rare earth ion concentration in the leaching solution is high, so no optimization is required.

[0101] For injection zone 5: α5 < α a Q5 > Q a c5 < c a This indicates that the rare earth grade of the ore body in this area is low, the leaching solution flow rate is large, and the rare earth ion concentration in the leaching solution is low. Therefore, the injection grid size should be increased to 6m × 6m, and the injection intensity reduced to 0.5m. 3 / d.

[0102] Under the injection control method provided in this embodiment of the invention, after leaching, the leaching rate of ion-adsorption rare earth elements in all five regions reached over 96.2%. Compared with ion-adsorption rare earth mines with similar topography and geological conditions, the amount of leaching agent used to produce the same amount of rare earth concentrate under the same process conditions was reduced by 21%.

[0103] Example 2: This example 2 is for ion-adsorption rare earth mines without a natural liquid-collecting bottom plate, such as... Figure 3 The image shown is a front view of an ion-type rare earth in-situ leaching ore using a liquid collection tunnel, as illustrated in the example of this invention. Figure 3 The system includes: 1. Ore body; 2. Injection hole; 3. Injection pipeline; 4. High-level pool; 5. Non-ore zone; 6. Bedrock; 7. Liquid collection ditch; 9. Injection zone 1; 10. Injection zone 2; 11. Injection zone 3; 12. Injection zone 4; 13. Injection zone 5; 14. Liquid collection tunnel. The specific process is as follows:

[0104] (1) Obtain data on the distribution of ion-adsorption rare earth grades in ion-adsorption rare earth mines. Based on the exploration results of ion-adsorption rare earth mines, calculate the ion-adsorption rare earth grades at different locations in the mines and delineate the ion-adsorption rare earth ore body 1.

[0105] (2) Injection holes 2 are arranged on the overburden of the ion-adsorption rare earth ore body 1. The injection holes 2 are arranged in a "plum blossom" shape, with a row spacing × row spacing of 2m × 2m and a hole diameter of 0.1m. Injection pipes 3 are arranged between the injection holes 2 to transport the leaching agent (6wt% magnesium sulfate heptahydrate solution) in the high-level pool 4 to each injection hole 2. Water taps are installed above the injection holes 2 to control the injection intensity (initial injection intensity controlled at 0.8m). 3 / d). A ring of collection channels 7 and collection tunnels 14 are arranged along the foot of the ion-adsorption rare earth mine at the bottom of ore body 1 and the upper part of bedrock 6 in the non-ore zone 3 to intercept the leachate. The bottom surface of the collection tunnel 14 maintains a slope of 5‰ with the horizontal plane and slopes downward from the inside to the outside.

[0106] (3) With the collection tunnel as the center, the test ore block was divided into five injection zones, extending 8m to the left and right, namely injection zone 1 (9), injection zone 2 (10), injection zone 3 (11), injection zone 4 (12), and injection zone 5 (13), with a distance of 16m between adjacent injection zones. The amount of leaching collected by the collection tunnel represents the amount of leaching collected in each injection zone. The leachate from the five zones eventually converges at one end of the collection ditch.

[0107] (4) Calculate the average rare earth grade of the ore body in each injection zone:

[0108]

[0109] In the formula, α a α represents the average rare earth grade of the ore bodies in the five injection zones. i and m i Let represent the average rare earth grade and ore body mass of injection zone i, respectively. Where α1 = 0.43, α2 = 0.55, α3 = 0.87, α4 = 0.61, α5 = 0.46, m1 = 3746t, m2 = 4357t, m3 = 4722t, m4 = 4636t, m5 = 3585t. α is calculated as follows: a =0.60.

[0110] (5) Select some of the injection holes in the arranged injection holes 2 for injection. The selected injection holes are in the shape of "plum blossom". The row spacing of adjacent injection holes is 4m × row spacing = 4m.

[0111] (6) When the leaching begins to flow out of the leaching tunnel, the flow rate and rare earth ion concentration of the leaching solution in each leaching tunnel are measured, as well as the flow rate and rare earth ion concentration at the leaching solution confluence of the five injection zones.

[0112] (7) Calculate the average flow rate of leachate in each injection zone:

[0113]

[0114] In the formula, Q aQ represents the average flow rate across the five injection zones. i This represents the leachate flow rate in injection zone i. After 30 days of injection, Q1 = 45 m³ / s. 3 / d、Q2=56m 3 / d、Q3=58m 3 / d、Q4=72m 3 / d、Q5=63m 3 / d, calculate Q a =59m 3 / d.

[0115] (8) Calculate the average concentration of rare earth ions in the leachate of each injection zone:

[0116]

[0117] In the formula, c a c represents the average concentration of rare earth ions at the confluence of the leachates from the five injection zones. i This represents the rare earth ion concentration in the leachate from injection zone i. After 30 days of injection, c1 = 0.53 g / L, c2 = 0.56 g / L, c3 = 0.63 g / L, c4 = 0.49 g / L, and c5 = 0.42 g / L. The calculated concentration of rare earth ions is... a =0.52g / L.

[0118] (9) By comparing the leaching flow rate and rare earth ion concentration of each injection zone with the average leaching flow rate and rare earth ion concentration of the five injection zones, the in-situ leaching injection network density, injection intensity, and leaching agent concentration were adjusted. The specific process is as follows:

[0119] For injection zone 1: α1 < α a Q1 < Q a c1 > c a This indicates that the rare earth grade of the ore body in this area is low, the leaching solution flow rate is small, and the rare earth ion concentration in the leaching solution is high. Therefore, increasing the injection intensity to 1m is appropriate. 3 / d.

[0120] For injection zone 2: α2 < α a Q2 < Q a c2 > c a This indicates that the rare earth grade of the ore body in this area is low, the leaching solution flow rate is small, and the rare earth ion concentration in the leaching solution is high. Therefore, increasing the injection intensity to 1m is appropriate. 3 / d.

[0121] For injection zone 3: α3 > α a Q3 < Q a c3 > c aThis indicates that the rare earth grade of the ore body in this area is relatively high, the leaching solution flow rate is relatively low, and the rare earth ion concentration in the leaching solution is relatively high. At this time, the injection mesh density is increased to 4m×4m, and the injection intensity is increased to 1m. 3 / d.

[0122] For injection zone 4: α4 > α a Q4 > Q a c4 < c a This indicates that the rare earth grade of the ore body in this area is high, the leaching solution flow rate is high, and the rare earth ion concentration in the leaching solution is low. Therefore, the injection intensity should be reduced by 0.5m. 3 / d, the injection mesh density is increased to 4m×4m, and the leaching agent concentration is increased to 7wt% (magnesium sulfate heptahydrate).

[0123] For injection zone 5: α5 < α a Q5 > Q a c5 < c a This indicates that the rare earth grade of the ore body in this area is low, the leaching solution flow rate is large, and the rare earth ion concentration in the leaching solution is low. Therefore, the injection grid size should be increased to 6m × 6m, and the injection intensity reduced to 0.5m. 3 / d.

[0124] Under the injection control method provided in this embodiment of the invention, after leaching, the leaching rate of ion-adsorption rare earth elements in all five regions reached over 95.4%. Compared with ion-adsorption rare earth mines with similar topography and geological conditions, the amount of leaching agent used is reduced by 18% to produce the same amount of rare earth concentrate under the same process conditions.

[0125] In summary, the method described in the embodiments of the present invention has the following advantages:

[0126] (1) Based on information such as the grade of valuable elements in the ore body, the flow rate of the leaching solution, and the concentration of valuable elements in the leaching solution, the permeability of the ore body and the leaching of valuable elements are judged. The injection process is regulated according to the judgment results, including the regulation of injection network, injection intensity and injection concentration. This provides a reference for regulation, increases the controllable factors, and improves the accuracy and flexibility of regulation.

[0127] (2) It effectively suppressed the generation of leaching blind zones, reduced the amount of leaching agent, improved the leaching rate of valuable elements and the efficiency of leaching agent use, with the leaching rate of valuable elements reaching more than 95% and the amount of leaching agent reduced by more than 15%, effectively avoiding the occurrence of geological disasters such as landslides caused by improper injection control.

[0128] Furthermore, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware, and the corresponding program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0129] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for in-situ leaching of ore using variable mesh size injection, characterized in that, The method includes: Step 1: Obtain the grade distribution data of valuable elements in ion-adsorption rare earth mines based on the results of mine exploration, and delineate the valuable element ore bodies; Step 2: Arrange the injection and recovery works of the ion-adsorption rare earth mine according to the in-situ leaching process; Step 3: Select a portion of the injection holes from the arranged injection holes to perform sparse injection in the mine. The selected injection hole mesh size is larger than the designed minimum injection hole mesh size. After injection, collect the leachate according to the arranged collection project. Step 4: Measure the flow rate and concentration of valuable elements of the leachate collected by the liquid collection process; Step 5: Establish the relationship between the concentration of valuable elements in the leaching solution and the ore body mass, leaching agent volume, valuable element grade, and initial concentration of leaching agent; Step 6: Calculate the average grade of valuable elements in the overlying ore body, the average flow rate of the leachate, and the average concentration of valuable elements in the leachate in each controlled area of ​​the leaching project. In step 6, for mines with a natural liquid collection floor, the liquid collection engineering control area is divided by the diversion holes; for mines without a natural liquid collection floor, the liquid collection engineering control area is divided by the liquid collection roadway. The average grade of valuable elements in the overlying ore body of each liquid collection engineering control area is calculated according to the following formula: In the formula, α a Indicates the average grade of valuable elements in the overlying ore body of the liquid recovery project; α i and m i These represent the valuable element grade and ore body quality of the overlying ore body in the i-th liquid collection engineering control area, respectively. The average flow rate of each liquid collection control area is calculated using the following formula: In the formula, Q a Q represents the average flow rate within the controlled area of ​​the liquid collection process; T N represents the total flow rate at the confluence of leachate in each controlled area of ​​the liquid collection project; N represents the total number of controlled areas of the liquid collection project. According to Darcy's law, the actual flow rate of the i-th liquid collection engineering control area is expressed as: In the formula, Q i denoted as , where is the actual flow rate in the control area of ​​the i-th liquid collection project; F is the cross-sectional area of ​​the water passage; h is the total head loss; L is the seepage path length; I = h / L is the hydraulic gradient; k is the permeability coefficient; the actual flow rate in the control area of ​​the i-th liquid collection project is positively correlated with the permeability coefficient, cross-sectional area of ​​the water passage, and hydraulic gradient of the ore body in that area; The average concentration of valuable elements in the leachate from each controlled area of ​​the leachate collection project is calculated using the following formula: In the formula, c a This indicates the average concentration of valuable elements in the leachate collected by the leachate collection process; c i Q i Let represent the concentration of valuable elements in the leachate collected by the i-th collection process and the leachate flow rate, respectively. Step 7: Compare the average flow rate and actual value of the leachate collected by the collection project with the average concentration of valuable elements and the actual value. Based on the comparison results, adjust the in-situ leaching injection network, injection intensity and leaching agent concentration. The process of step 7 is as follows: If α i <α a Q i a c i <c a If , it means that the grade of valuable elements in the i-th liquid collection engineering control area is low, the flow rate of the leachate is small, and the concentration of valuable elements in the leachate is low. In this case, the liquid injection network should be densified.​ If α i <α a Q i a c i >c a If the value of the elements is low, the leachate flow rate is small, and the concentration of valuable elements in the leachate is high in the i-th liquid collection control area, then the injection intensity should be increased.​ If α i <α a Q i Q a c i <c a If the value of the elements is low in the i-th liquid collection control area, the leachate flow rate is high, and the concentration of valuable elements in the leachate is low, then the liquid injection network should be expanded and the liquid injection intensity reduced. If α i <α a Q i Q a c i >c a If , it means that the valuable element grade is low, the leachate flow rate is large, and the valuable element concentration in the leachate is high in the i-th liquid collection engineering control area, and no adjustment is required. If α i >α a Q i a c i <c a If the value of the elements is high in the i-th liquid collection control area, the leaching liquid flow rate is low, and the concentration of valuable elements in the leaching liquid is low, then the injection network density should be increased and the concentration of leaching agent should be increased.​ If α i >α a Q i a c i >c a If the value of the elements is high in the i-th liquid collection control area, the leachate flow rate is low, and the concentration of valuable elements in the leachate is high, then the injection network density should be increased and the injection intensity should be increased.​ If α i >α a Q i Q a c i <c a If , it means that the grade of valuable elements in the i-th liquid collection engineering control area is high, the flow rate of the leachate is high, and the concentration of valuable elements in the leachate is low. At this time, the injection intensity should be reduced, the injection network density should be increased, and the concentration of leaching agent should be increased. If α i >α a Q i Q a c i >c a This indicates that the i-th liquid collection engineering control area has a high grade of valuable elements, a high flow rate of leachate, and a high concentration of valuable elements in the leachate. In this case, the liquid injection network should be densified.

2. The in-situ leaching method with variable mesh size injection according to claim 1, characterized in that, In step 2, injection holes are arranged on the overburden of the ore body according to certain hole network parameters, and injection pipes are arranged between the injection holes to transport the leaching agent in the high-level pool to each injection hole through the injection pipes; a water tap is installed above the injection hole to control the injection intensity; and a liquid collection project is arranged at the bottom of the ore body to intercept or guide the leaching liquid. The injection holes are arranged in a quincunx pattern, with a row spacing of 2m × row spacing of 2m between adjacent injection holes, a hole diameter of 0.1 to 0.18m, and a hole depth of 0.5 to 1m when ore is encountered. For mines with natural liquid collection bottom plates, liquid collection projects consisting of diversion holes and collection ditches are arranged. Both the collection ditches and diversion holes are located at the foot of the mountain. The diversion holes are excavated vertically upwards at an inclination of 3‰ to 5‰. For mines without a natural liquid collection floor, a liquid collection project consisting of diversion holes, liquid collection roadways, and liquid collection ditches is implemented. The diversion holes are located on both sides of the liquid collection roadway, while the liquid collection ditches and roadways are located at the foot of the mountain. The liquid collection roadways run parallel to the mountain's orientation, with adjacent liquid collection roadways spaced 15–20 meters apart. The bottom surface of the liquid collection roadways maintains a slope of 3‰–5‰, cutting downwards from the inside out.

3. The in-situ leaching method with variable mesh size injection according to claim 1, characterized in that, In step 4, For mines with natural liquid collection bottom plates, the liquid collection process is measured at fixed times and locations every day, namely the flow rate of leachate at the outlet of each guide hole and the confluence of the liquid collection ditch, and the concentration of valuable elements in the leachate is detected. For mines without a natural liquid collection base, the liquid collection process is measured at fixed times and locations every day, namely the flow rate of leachate at each guide hole, the outlet of the liquid collection roadway, and the confluence of the liquid collection ditch, and the concentration of valuable elements in the leachate is detected.

4. The in-situ leaching method for variable mesh size injection according to claim 1, characterized in that, In step 5, the relationship is established based on the Kerr model describing the ion exchange selectivity coefficient, which is expressed as follows: In the formula, K is the selection coefficient of the Kerr model; [N n+ ] and [M m+ [ ] represent the molar concentrations of cations and valuable elements in the liquid phase leaching agent, respectively, in mol / L; [NX n ] and [MX m [] represents the molar concentration of cations and valuable elements in the solid phase leaching agent, respectively, in mol / g; Initially, there are no valuable elements in the liquid phase and no adsorbed leaching agent cations on the solid phase. According to the equivalence principle, after ion exchange equilibrium, the relationship between the number of moles of leaching agent cations in the solid phase and the number of moles of valuable elements in the liquid phase is as follows: mm s [NX n ]=nV L [M m+ ] (2) In the formula, m s The mass of the rare earth mineral sample is expressed in g; V L Let L be the volume of the solution. Before and after the ion exchange reaction, the mass conservation of both leaching agent cations and valuable elements in the system should be satisfied. After ion exchange equilibrium, the sum of the molar number of leaching agent cations in the liquid phase and the molar number of leaching agent cations in the solid phase is equal to the molar number of leaching agent cations in the liquid phase before the ion exchange. Therefore: [N n+ ]V L +[NX n ]m s =[N n+ ]0V L (3) In the formula, [N n+ [0] represents the molar concentration of cations in the liquid leaching agent before leaching, in mol / L; Similarly, if the sum of the number of moles of valuable elements in the liquid phase and the number of moles of valuable elements in the solid phase equals the number of moles of valuable elements in the solid phase before ion exchange, then: [M m+ ]V L +[MX m ]m s =[MX m ]0m s (4) In the formula, [MX m [0] represents the molar concentration of valuable elements in the solid phase before ion exchange, in mol / g; By rearranging equations (2) to (4), and expressing the molar concentrations of solid-phase leaching agent cations, liquid-phase leaching agent cations, and solid-phase valuable elements in terms of liquid-phase valuable element molar concentrations, we have: Substituting equations (5) to (6) into equation (1), and using the concentration of valuable elements in the liquid phase to represent the selection coefficient K of the Kerr model, then: Molar concentration of valuable elements in the solid phase before ion exchange [MX] m ]0 is represented as: In the formula, α represents the grade of the valuable element, in g / g; M RE This represents the relative molar mass of a valuable element, expressed in g / mol. Substituting equation (9) into equation (8), we obtain the expression for the Kerr model selection coefficient K, which includes the concentration of valuable elements in the liquid phase, the rare earth grade, and the initial concentration of the leaching agent: If the selection coefficient K is considered a constant, then the concentration of valuable elements in the liquid phase after the reaction reaches equilibrium is inversely proportional to the volume of the leaching agent, and directly proportional to the ore body quality, the grade of valuable elements, and the initial concentration of the leaching agent.

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