A method of unblocking an ore bed in an in-situ leaching process for uranium

Abstract

The present application relates to the technical field of uranium in-situ leaching, and particularly relates to a method for dredging a uranium ore bed during in-situ leaching of uranium. The method comprises the following steps: according to the properties of the ore, performing statistical analysis on the uranium leaching rate, acid consumption and characteristic ion dissolution of the ore, and determining an acid consumption step; when the amount of liquid pumped from a hole is reduced to less than 20% of the acceptance water amount, stopping pumping and injecting a sulfuric acid solution into the hole, the concentration of the sulfuric acid corresponding to the acid concentration of the i-th level of the acid consumption step; after stopping the injection of the sulfuric acid solution, performing a hole sealing operation on the hole; starting the pumping and injection cycle, and ending the dredging operation; if the amount of liquid pumped from the hole is again reduced to less than 20% of the acceptance water amount, returning to perform the step two, and during the subsequent acid injection dredging operation, the concentration of the sulfuric acid solution is increased to the acid concentration corresponding to the i+1-th level of the acid consumption step. The present application makes the flow direction of the dredging agent and the leaching solution opposite, achieves the purpose of dissolving, dredging the blocked ore bed and restoring the pumping and injection amount, and has a wide range of applications and does not introduce other ions.

Description

Technical Field

[0001] This invention relates to the field of uranium leaching technology, and more particularly to a method for clearing ore layers during uranium leaching mining. Background Technology

[0002] During acid leaching, sulfuric acid reacts chemically with the ore, causing ions such as iron, aluminum, calcium, and uranium to migrate into the solution. As this migration occurs, sulfuric acid is continuously consumed, the pH of the solution changes, and some metal ions undergo hydrolysis and precipitation. These precipitates emerge from the liquid phase and adhere to the surface of the ore layer, causing chemical blockage. Simultaneously, fine-grained solid particles such as rock fragments reduce the permeability of the ore layer.

[0003] To address the issue of reduced injection volume caused by ore layer blockage during acid leaching of uranium, commonly used methods include air washing, piston washing, and chemical washing to clear the ore layer.

[0004] Air well washing includes air compressor well washing and compressed air well washing. It refers to a well washing method that uses compressed air provided by an air compressor as the well washing medium. It is one of the most common well washing methods in production drilling and is generally applicable to wells of various depths, water volumes, and drilling during construction or production.

[0005] Piston well-washing structures still use single-acting and double-acting iron pistons, while wooden pistons have been largely phased out in the market. The piston rubber is made from coal mine conveyor belts. If the piston is connected to drill pipe, the outer diameter of the rubber should be 3-5 mm larger than the inner diameter of the well casing.

[0006] For acid leaching mines, chemical well washing typically uses hydrochloric acid, hydrofluoric acid, or a combination of acids. The cleaning range is relatively larger than that of air compressors and pistons. Micro-acid well washing refers to the chemical reaction between hydrochloric acid injected into the blocked borehole and the exposed limestone or other blockages. Easily soluble CaCl2 becomes a solution, and CO2 escapes as a gas, dissolving the carbonate rock. This causes corrosion and expansion of water-conducting fractures and pores in the limestone formation, thus clearing the aquifer's water channels. The characteristic of dilute hydrochloric acid, which dissolves blockages while preventing the formation of new precipitates, makes it suitable for blockages caused by alkaline or weakly acidic precipitates.

[0007] Hydrofluoric acid well washing typically involves adding sulfuric acid and ammonium bifluoride to the borehole to be washed, sealing the borehole for 3-5 days, and then using an air compressor to flush out the washing fluid, thus clearing the blockage in the mineral layer. The effective method utilizes the strong corrosive properties of the hydrofluoric acid produced by the reaction.

[0008] Other acid-based chemical well washing methods involve injecting a washing agent into the borehole that contains formation water and other ions that are present at low or no concentration in the leaching agent, such as F. - Cl -On the one hand, the washing water from the well cannot be directly introduced into the hydrometallurgical system, resulting in metal loss. On the other hand, other ions remaining in the formation reduce the resin adsorption efficiency and may even cause poisoning.

[0009] Before a new mining area using the acid leaching process is put into production, acidizing is carried out. The acidizing methods are direct acidizing or pre-acidizing. Direct acidizing involves injecting leaching agent into the injection well and extracting the leaching fluid from the pumping well. This ensures a balance between injection and pumping during the acidizing period, but the concentration of the pumped fluid cannot reach the industrial required concentration in the early stages of acidizing. Pre-acidizing involves injecting leaching agent into a designated pumping well without the injection well operating. When the leaching agent fills half of the ore well cavity, it is injected from the injection well and the leaching fluid is extracted from the pumping well. The advantage of pre-acidizing is that the uranium concentration of the leaching fluid reaches the industrial required concentration when the fluid is extracted from the pumping well.

[0010] Among the aforementioned technologies, air and piston well washing mainly target the borehole itself and the surrounding mineral formations. For well washing in deep mineral formations exceeding 600 meters in depth, the air compressor has a high load and low efficiency, and the piston may damage the casing. Chemical well washing uses various acids to introduce other ions into the formation or strongly corrode and dissolve components such as SiO2, which is not conducive to subsequent hydrometallurgical treatment, and the discharge of well washing water may cause metal loss. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a method for clearing ore layers in the process of in-situ leaching uranium mining. This method involves injecting sulfuric acid of different concentrations into the extraction hole so that the flow direction of this sulfuric acid is opposite to that of the leaching solution during normal leaching, thereby achieving the purpose of dissolving and clearing the blocked ore layer and restoring the injection volume.

[0012] This invention provides a method for clearing ore layers during in-situ leaching uranium mining, comprising the following steps:

[0013] Step 1: Based on the properties of the ore, perform statistical analysis on its uranium leaching rate, acid consumption, and characteristic ion leaching performance to obtain the relationship curve of leaching agent acid concentration-uranium leaching rate-ore acid consumption, and determine the acid consumption step based on this curve.

[0014] Step 2: When the amount of liquid pumped from the extraction hole decreases to less than 20% of the acceptance water volume, stop pumping and inject sulfuric acid solution into the extraction hole. The sulfuric acid concentration corresponds to the acid concentration of the i-th stage of the acid consumption step.

[0015] Step 3: After stopping the injection of sulfuric acid solution, perform a hole-sealing operation on the extraction hole;

[0016] Step 4: Start the injection fluid circulation to end this unblocking operation;

[0017] Step 5: If the amount of liquid pumped from the extraction hole decreases again to below 20% of the acceptance water volume, return to step 2. During the last acid injection and unblocking operation, the sulfuric acid solution concentration is increased to the acid concentration corresponding to the i+1th acid consumption step.

[0018] i is an integer from 1 to 5.

[0019] Preferably, the step two further includes:

[0020] During the acid leaching process, after the ore layer is acidified, formal leaching begins. With the submersible pump maintaining a relatively constant pumping capacity and power, the pumping volume of the extraction hole is continuously monitored. When the pumping volume of the extraction hole is found to have decreased to less than 20% of the acceptance volume, step two is performed.

[0021] Preferably, in step two, sulfuric acid solution is injected into the extraction hole at a flow rate of 3 to 4 cubic meters per hour.

[0022] Preferably, in step two, sulfuric acid solution is continuously injected for 3 to 8 days, depending on the permeability and the migration rate of sulfate ions.

[0023] Preferably, in step three, the time for the hole-sealing operation is 20 to 30 hours.

[0024] Preferably, in step one, the leaching agent is sulfuric acid, and the acid concentration of the acid consumption step increases step by step.

[0025] Preferably, the concentration of the sulfuric acid solution injected in the later injection is higher than the concentration of the sulfuric acid solution injected in the previous injection.

[0026] Preferably, when the acid concentration of the leaching agent is less than or equal to 10.1 g / L, the ore exhibits three near-step-type rapid acid consumption steps, namely:

[0027] Step I: When the leaching acid concentration is 1.5–2.3 g / L, the acid consumption is 1.3–1.9 kg / t of ore;

[0028] Step II: When the leaching acid concentration is 3.2–7.6 g / L, the acid consumption is 6.2–8.8 kg / t of ore;

[0029] Step III: When the leaching acid concentration is 8.0-10.1 g / L, the acid consumption is 14.3-15.2 kg / t.

[0030] For steps III and above: when the leaching acid concentration is above 10.1 g / L, the acid consumption is greater than 15.2 kg / t.

[0031] Compared with existing technologies, the ore layer clearing method in the in-situ leaching uranium mining process of the present invention has the following beneficial effects:

[0032] (1) Compared with air washing and piston washing, the method described in this invention is not only applicable to shallow ore dredging but also to deep ore dredging exceeding 600 meters in depth. Energy consumption is negligible, it has virtually no impact on the casing wall, and it has a strong ability to clean chemical deposits adhering to the inside and outside of the casing. In contrast, air washing and piston washing are less efficient and less effective for deep ore dredging, consume more energy, and piston washing can easily damage the casing. It is not limited by the burial depth of the ore layer.

[0033] (2) Compared with other acid-based chemical well washing methods, the method described in this invention does not introduce other ions into the mineralized water system of the leaching area, and has little impact on subsequent leachate treatment;

[0034] (3) Compared with direct acidification and advanced acidification:

[0035] a) Depending on the mining stage, the method described in this invention is applicable to the entire cycle of the acid leaching process, while direct acidification and advanced acidification are applicable to the acidification period (pre-leaching stage) of the acid leaching process.

[0036] b) Different situations and purposes. The method described in this invention addresses the problem of decreased injection volume due to formation blockage after a period of time following the injection of sulfuric acid leaching agent during acid leaching. This method restores the injection volume. Direct acidification and pre-acidification, on the other hand, are used to eliminate or reduce the risk of blockage in advance by acidifying the ore layer before blockage symptoms appear in the formal leaching formation, thus avoiding metal precipitation loss.

[0037] c) Even if the ore layer has been pretreated with direct acidification and advanced acidification, problems such as ore layer blockage and reduced pumping volume may still occur during the formal leaching process. The method described in this invention can be used to clear the blockage.

[0038] d) Methods such as direct acidification and advanced acidification generally use a fixed concentration of sulfuric acid. During the formal leaching process, the sulfuric acid concentration is gradually reduced based on cost considerations at each leaching stage. The method described in this invention determines multiple unblocking liquid acid concentrations based on the stepped distribution characteristics of ore acid consumption, and gradually increases the unblocking liquid acid concentration as the number of unblocking cycles increases.

[0039] (4) The method described in this invention can handle the situation where the pumping volume of the same borehole decreases multiple times by sequentially increasing the concentration of the dredging liquid acid according to the step-shaped distribution characteristics of the acid consumption of the ore.

[0040] (5) By using the method of back-injection through the extraction hole, the acid concentration of the leaching agent can be avoided directly. The reagent consumption is relatively small, the leaching solution is easy to block and the ion concentration increases slowly.

[0041] After the method was implemented and the injection-extraction cycle was restored, the drilling fluid extraction volume could significantly increase by 49%-145%, and this effect was maintained for 2-6 months, indicating that the ore layer unblocking was effective. Repeated unblocking can still effectively increase the extraction volume. Attached Figure Description

[0042] Figure 1 This represents the relationship curve between leaching agent acid concentration, uranium leaching rate, and ore acid consumption in the stirred leaching test.

[0043] Figure 2 This diagram illustrates the backflow of the drain cleaner.

[0044] In the picture:

[0045] 1-Wellhead device, 2-Drawing hole, 3-Injection hole, 4-Clearing fluid. Detailed Implementation

[0046] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0047] Embodiments of the present invention disclose a method for clearing ore seams during in-situ leaching uranium mining, comprising the following steps:

[0048] Step 1: Based on the ore properties, perform statistical analysis on its uranium leaching rate, acid consumption, and characteristic ion leaching performance to obtain the relationship curve of leaching agent acid concentration-uranium leaching rate-ore acid consumption, and determine the acid consumption step accordingly;

[0049] Step 2: When the amount of liquid pumped from the extraction hole decreases to less than 20% of the acceptance water volume, stop pumping and inject sulfuric acid solution into the extraction hole. The sulfuric acid concentration corresponds to the acid concentration of the i-th stage of the acid consumption step.

[0050] Step 3: After stopping the injection of sulfuric acid solution, perform a hole-sealing operation on the extraction hole;

[0051] Step 4: Start the injection fluid circulation to end this unblocking operation;

[0052] Step 5: If the amount of liquid pumped from the extraction hole decreases again to below 20% of the acceptance water volume, return to step 2. During the last acid injection and unblocking operation, the sulfuric acid solution concentration is increased to the acid concentration corresponding to the i+1th acid consumption step.

[0053] i is an integer from 1 to 5.

[0054] This invention involves injecting a dredging fluid, namely sulfuric acid solution, into the extraction hole. First, the sulfuric acid solution is consistent with the leaching agent to avoid the introduction of other ions. Second, the flow direction of this sulfuric acid solution is opposite to the flow direction of the leaching solution during normal leaching, so as to achieve the purpose of dissolving and clearing the blocked mineral layer and restoring the injection volume. Third, sulfuric acid solutions of different concentrations are injected into the extraction hole, and the direction is matched with the acid consumption step.

[0055] The method of the present invention is described in detail below according to the steps:

[0056] Step 1: Based on the properties of the ore, perform statistical analysis on its uranium leaching rate, acid consumption, and characteristic ion leaching performance to obtain the relationship curve of leaching agent acid concentration-uranium leaching rate-ore acid consumption, and determine the acid consumption step based on this curve.

[0057] The acid consumption steps refer to the different stages of leaching acid concentration and acid consumption obtained by refining the relationship between the change in leaching agent acid concentration and leaching results based on the actual leaching process.

[0058] The leaching agent is sulfuric acid, and the acid concentration of the acid consumption steps increases progressively.

[0059] The existence of acid consumption steps is closely related to the dissolution of rapidly acid-consuming minerals, which can be analyzed from the dissolution of characteristic elements.

[0060] Step 2: During the acid leaching process, after the ore layer is acidified, formal leaching begins. With the submersible pump maintaining a relatively constant pumping capacity and power, the pumping volume in the extraction hole is continuously monitored. When the pumping volume in the extraction hole is found to decrease to below 20% of the acceptance water volume, pumping is stopped, and sulfuric acid solution is injected into the extraction hole. The sulfuric acid concentration corresponds to the acid concentration of the i-th stage of the acid consumption step; i is an integer from 1 to 5.

[0061] The value of i starts from 1 and increases gradually. That is: when step two is executed for the first time, i is 1; when step two is executed for the second time, i is 2; when step three is executed for the third time, i is 3; and so on.

[0062] If pre-acidification is performed during leaching, then pre-acidification is equivalent to performing the first stage of acidification. When step two is performed for the first time, the sulfuric acid concentration corresponds to the acid concentration of the second stage of the acid consumption step.

[0063] Preferably, sulfuric acid solution is injected into the extraction hole at a flow rate of 3 to 4 cubic meters per hour.

[0064] Depending on the permeability and the migration rate of sulfate ions, the sulfuric acid solution is continuously injected for 3 to 8 days.

[0065] Step 3: After stopping the injection of sulfuric acid solution, perform a hole-sealing operation on the extraction hole;

[0066] The time for the hole-sealing operation is 20 to 30 hours, preferably 24 hours.

[0067] Step 4: Start the injection fluid circulation to end this unblocking operation;

[0068] After the blockage operation is completed, the injection fluid circulation is restarted to complete one unblocking operation. If blockage occurs again during actual uranium leaching, proceed to step five.

[0069] Step 5: If the amount of liquid pumped from the extraction hole decreases again to below 20% of the acceptance water volume, return to step 2. During the last acid injection and unblocking operation, the sulfuric acid solution concentration is increased to the acid concentration corresponding to the i+1th acid consumption step.

[0070] The concentration of the sulfuric acid solution injected in the later injection is higher than that injected in the previous injection.

[0071] According to the method of the present invention, experiments were conducted on ore from a certain deposit, and the relationship between leaching agent acid concentration, uranium leaching rate, and ore acid consumption was statistically analyzed.

[0072] When the leaching agent acid concentration is less than or equal to 10.1 g / L, the ore exhibits three near-step-type rapid acid consumption steps, namely:

[0073] Step I: When the leaching acid concentration is 1.5–2.3 g / L, the acid consumption is 1.3–1.9 kg / t of ore;

[0074] Step II: When the leaching acid concentration is 3.2–7.6 g / L, the acid consumption is 6.2–8.8 kg / t of ore;

[0075] Step III: When the leaching acid concentration is 8.0-10.1 g / L, the acid consumption is 14.3-15.2 kg / t.

[0076] For steps III and above: when the leaching acid concentration is above 10.1 g / L, the acid consumption is greater than 15.2 kg / t.

[0077] The existence of this acid consumption step is closely related to the dissolution of rapidly acid-consuming minerals, and can be analyzed from the dissolution of characteristic elements.

[0078] Based on the above acid consumption steps, the acid concentration values ​​C1, C2, C3, and C4 of the unclogging solution can be selected from the ranges of 1.5–2.3 g / L, 3.2–7.6 g / L, 8.0–10.1 g / L, and above 10.1 g / L, respectively, depending on the number of unclogging cycles.

[0079] To further understand the present invention, the following detailed description of the ore layer clearing method in the in-situ leaching uranium mining process provided by the present invention is provided in conjunction with embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0080] Example 1: Determining the concentration of the unclogged liquid acid

[0081] The basic acid consumption of the ore in a certain deposit is not high, so the focus is on investigating the low acid concentration conditions of the leaching agent. In order to investigate the uranium leaching rate, acid consumption, and characteristic ion dissolution performance, the acid concentration values ​​of the leaching agent were refined based on the on-site preparation error of the acid concentration. The results of the stirring leaching test are shown in Table 1.

[0082] Table 1 Results of acid stirring leaching test

[0083]

[0084] In terms of leaching rate, when the acid concentration of the leaching agent is 1.5-2.3 g / L, 60-68% of uranium is dissolved; when the acid concentration of the leaching agent reaches 3.6 g / L, the uranium leaching rate reaches 97%; and the leaching rate exceeds 90% between 3.6 g / L and 7.6 g / L, with little difference in acid consumption, indicating that low-acid leaching of this ore is feasible.

[0085] The relationship between leaching agent acid concentration, uranium leaching rate, and ore acid consumption is shown in the figure. Figure 1 curve.

[0086] Figure 1 The data shows that, considering acid consumption, when the leaching agent acid concentration is less than or equal to 10.1 g / L, the ore exhibits three near-step-like rapid acid consumption steps, namely:

[0087] In step I, when the leaching acid concentration is 1.5–2.3 g / L, the acid consumption is 1.3–1.9 kg / t of ore.

[0088] For step II, when the leaching acid concentration is 3.2–7.6 g / L, the acid consumption is 6.2–8.8 kg / t of ore.

[0089] When the leaching acid concentration is 8.0–10.1 g / L at step III, the acid consumption is 14.3–15.2 kg / t.

[0090] When the step level is above III and the leaching acid concentration is above 10.1 g / L, the acid consumption is greater than 15.2 kg / t.

[0091] The existence of this acid consumption step is closely related to the dissolution of rapidly acid-consuming minerals, and can be analyzed from the dissolution of characteristic elements.

[0092] Based on the above acid consumption steps, the acid concentration values ​​C1, C2, C3, and C4 of the unclogging solution can be selected from the ranges of 1.5–2.3 g / L, 3.2–7.6 g / L, 8.0–10.1 g / L, and above 10.1 g / L, respectively, depending on the number of unclogging cycles.

[0093] Example 2: Validation of dredging methods on simulated ore pillars

[0094] A simulated mineral layer was formed by filling a φ30 transparent acrylic column with natural-sized ore. The two ends were filled with gravel to keep the mineral layer stable during the leaching process. A high-level tank was used to drive the solution into the mineral layer, and a bottom-feed method was used to ensure that the pressure difference ΔP between the two ends of the mineral layer was stable. A graduated cylinder was used to collect the leachate and measure the change in the volume of the leachate over the dredging time.

[0095] First, water is injected into the ore layer. Once the flow rate stabilizes, a drainage agent is injected into the ore layer.

[0096] The concentrations of the drain cleaner were 2 g / L, 4 g / L, 10 g / L, and 15 g / L, respectively.

[0097] The concentrations of characteristic ions such as Mg and Al increased significantly, the mineral dissolution rate accelerated, and the amount of liquid extracted increased significantly.

[0098] Example 3: On-site dredging case of ground flooding

[0099] In a newly mined area of ​​an acid leaching mine, the ore deposit is buried at a depth of more than 600 meters. The ore layer is directly acidified to a pH of 2-3 using 1-3.5 g / L sulfuric acid, and then formal leaching begins. The leaching agent used is 3.5-7.5 g / L sulfuric acid.

[0100] During the initial operation, the leaching agent acidity was controlled at 3.0 g / L to 3.5 g / L for 24 days. The water volume showed a slow decreasing trend, and the uranium concentration also increased relatively slowly. Subsequently, the leaching agent acidity was increased to 5.0 g / L to 5.5 g / L, and the water volume began to decrease. During the period of water volume decrease, the leaching agent acidity was further increased to 7.0 g / L to 7.5 g / L until the water volume decreased to 13 m³. 3 / h, during which an air compressor was used to clean some of the drill holes, but the cleaning effect was poor and could not restore the water volume. The cleaning effect could only maintain the current water volume.

[0101] Subsequently, the method described in this invention was used to carry out ore layer dredging work. First, the pumping and injection of fluid in the unit to be dredged was stopped. Then, 5 g / L sulfuric acid was used as the dredging fluid and injected into the pumping hole. The back-injection process was as follows. Figure 2 As shown, the injection time was 3 days, the soaking time was 1 day, and then the pumping was resumed.

[0102] The unblocking work was carried out sequentially on the four extraction holes (four units), which achieved significant results, and the water volume was restored to 20m³. 3 / h is running stably.

[0103] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0104] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for clearing ore layers during in-situ leaching uranium mining, characterized in that, Includes the following steps: Step 1: Based on the ore properties, statistical analysis is performed on its uranium leaching rate, acid consumption, and characteristic ion leaching performance to obtain the relationship curve of leaching agent acid concentration-uranium leaching rate-ore acid consumption, and the acid consumption step is determined accordingly; the leaching agent is sulfuric acid, and the acid concentration of the acid consumption step increases step by step. Step 2: When the amount of liquid pumped from the extraction hole decreases to less than 20% of the acceptance water volume, stop pumping and inject sulfuric acid solution into the extraction hole. The concentration of the sulfuric acid solution corresponds to the acid concentration of the i-th stage of the acid consumption step. Step 3: After stopping the injection of sulfuric acid solution, perform a hole-sealing operation on the extraction hole; Step 4: Start the injection fluid circulation to end this unblocking operation; Step 5: If the amount of liquid pumped from the extraction hole decreases again to below 20% of the acceptance water volume, return to step 2. During the last acid injection and unblocking operation, the sulfuric acid solution concentration is increased to the acid concentration corresponding to the i+1th acid consumption step. i is an integer from 1 to 5; The process preceding step two also includes: During the acid leaching process, after the ore layer is acidified, formal leaching begins. With the submersible pump maintaining a relatively constant pumping capacity and power, the pumping volume of the extraction hole is continuously monitored. When the pumping volume of the extraction hole is found to have decreased to less than 20% of the acceptance volume, step two is performed.

2. The method for clearing ore layers during in-situ leaching uranium mining according to claim 1, characterized in that, In step two, sulfuric acid solution is injected into the extraction hole at a flow rate of 3-4 cubic meters per hour.

3. The method for clearing ore layers during in-situ leaching uranium mining according to claim 2, characterized in that, In step two, sulfuric acid solution is continuously injected for 3 to 8 days, depending on the permeability and the migration rate of sulfate ions.

4. The method for clearing ore layers during in-situ leaching uranium mining according to claim 1, characterized in that, In step three, the time for the hole-sealing operation is 20 to 30 hours.

5. The method for clearing ore layers during in-situ leaching uranium mining according to claim 1, characterized in that, The concentration of the sulfuric acid solution injected in the second injection is higher than that injected in the previous injection.

6. The method for clearing ore layers during in-situ leaching uranium mining according to claim 1, characterized in that, When the leaching agent acid concentration is less than or equal to 10.1 g / L, the ore exhibits three near-step-type rapid acid consumption steps, namely: Step I: When the leaching acid concentration is 1.5~2.3g / L, the acid consumption is 1.3~1.9kg / t of ore; Step II: When the leaching acid concentration is 3.2~7.6 g / L, the acid consumption is 6.2~8.8 kg / t ore; Step III: When the leaching acid concentration is 8.0~10.1 g / L, the acid consumption is 14.3~15.2 kg / t ore; For steps III and above: when the leaching acid concentration is above 10.1 g / L, the acid consumption is greater than 15.2 kg / t of ore.

Images