A method for increasing the uranium concentration of uranium leaching solution in situ leaching

Abstract

The present invention belongs to the technical field of in-situ uranium leaching, and specifically relates to a method for increasing the uranium concentration of in-situ uranium leaching solution. The method comprises the following steps: determining the series connection sequence of mining areas; connecting the liquid extraction main pipe of the previous mining area with the liquid injection main pipe of the next mining area according to the series connection sequence of mining areas determined in step one; and connecting the leaching agent pipeline with the liquid injection main pipes of each mining area respectively. According to the series connection sequence of mining areas, the valves of the liquid extraction main pipe and the liquid extraction main pipe of the last mining area are opened, and the submersible pumps of the liquid extraction holes of each mining area are started in sequence from back to front to maintain the balance of extraction and injection of the mining area, and then the amount of leaching agent added is calculated according to the leaching agent concentration demand of the corresponding mining area and the residual leaching agent concentration in the leaching solution of the previous mining area. The method superimposes the uranium leached from multiple mining areas, and at the same time, the uranium concentration of the leaching solution is increased, and the residual leaching agent in the leaching solution is reused, thereby effectively improving the production capacity of the in-situ leaching mine and reducing the material consumption during the in-situ leaching of uranium.

Description

Technical Field

[0001] The invention belongs to the technical field of in-situ uranium leaching, and specifically relates to a method for increasing the uranium concentration of in-situ uranium leaching solution. Background Art

[0002] In-situ uranium leaching is a new type of uranium mining method that integrates mining and smelting. Under natural burial conditions, a leaching solution is injected into a mineral layer with a certain permeability to selectively leach the uranium in it, and then the leaching solution is lifted to the surface for uranium extraction.

[0003] In the process of in-situ uranium leaching, how to obtain a higher uranium concentration in the leachate and control the leaching cost has always been the focus of the industry. Especially in the middle and late stages of leaching in the operating mining area, the uranium concentration in the leachate is relatively low. To achieve the designed leaching rate, it needs to be continuously operated for a long time. However, the reagents, electricity, and resources required for subsequent hydrometallurgical treatment in the leaching process do not decrease as the uranium concentration in the leachate decreases, resulting in poor leaching efficiency. When the hydrometallurgical treatment capacity reaches saturation, the decrease in uranium concentration in the leachate will also lead to a decrease in production capacity. If leaching is not continued, the scarce and precious uranium resources discovered in the development will be wasted. In view of this, a method for increasing the uranium concentration in the leachate in the middle and late stages of leaching in the development mining area is proposed. Summary of the invention

[0004] The purpose of the present invention is to increase the uranium concentration of in-situ leaching uranium leaching solution and reduce the uranium leaching cost.

[0005] The solution of the present invention is:

[0006] A method for increasing the uranium concentration of an in-situ leaching uranium solution comprises the following steps:

[0007] Step 1: Determine the order of the mining area series connection; it is determined according to the leaching stage of the mining area, the difference between the uranium concentration of the leachate and the concentration of the remaining leaching solution, and the geographical location;

[0008] Step 2: Connect the liquid extraction main pipe with the liquid injection main pipe; according to the series connection sequence of the mining areas determined in step 1, connect the liquid extraction main pipe of the previous mining area with the liquid injection main pipe of the next mining area;

[0009] Step 3: Connect the leaching agent main pipe with the liquid injection main pipe; connect the leaching agent pipeline with the liquid injection main pipes of each mining area respectively.

[0010] Step 4: Multiple mining areas are operated in series. According to the series order of the mining areas, open the valve connecting the last mining area's pumping main pipe with the well site's main pumping pipe, and start the submersible pumps of the pumping holes of each mining area from back to front.

[0011] In the step 1, the number of mining areas connected in series is N, where N≥2.

[0012] In the step 1, the leaching stage of the mining area is considered. If the mining area with a leaching rate higher than 90% of the designed leaching rate and the mining area with a leaching rate lower than 90% of the designed leaching rate coexist, the mining area with a leaching rate higher than 90% of the designed leaching rate is in the front of the series connection.

[0013] In the step 1, when the difference between the concentration of uranium in the leaching solution of the mining areas to be connected in series and the concentration of the remaining leaching agent is less than or equal to 10%, the mining areas are connected in series from far to near in terms of geographical location.

[0014] In the step 1, when at least one of the uranium concentration in the leaching solution of the mining areas to be connected in series and the concentration of the remaining leaching solution is greater than 10%, the concentration of the remaining leaching solution in the mining areas is compared; when the difference in the concentration of the remaining leaching agent in the leaching solution of the mining areas to be connected in series is greater than 10%, the mining area with a higher concentration of the remaining leaching agent is placed in front; when the difference in the uranium concentration in the leaching solution of the mining areas to be connected in series and the concentration of the remaining leaching agent is less than or equal to 10%, if the difference in the uranium concentration in the leaching solution between the mining areas to be connected in series is greater than 10%, the mining area with a higher concentration of uranium in the leaching solution is placed at the back.

[0015] In the step 2, if the pumping pressure of the previous mining area cannot meet the injection pressure requirement of the next mining area, a pipeline pump is installed on the pipeline to increase the pressure.

[0016] In the step three, a suitable mixing device is selected according to the type of the leaching agent to uniformly mix the leaching agent with the solution in the injection main pipe.

[0017] In the step four, while starting the submersible pump of the extraction hole of a certain mining area, the valve of the injection hole of the next mining area is adjusted to maintain the extraction and injection balance of the next mining area; until the submersible pump of the extraction hole of the first mining area is started, the valve connecting the injection main pipe of the first mining area and the well field injection main pipe is opened, and the valve of the injection hole of the first mining area is adjusted to maintain the extraction and injection balance of the first mining area.

[0018] In the fourth step, after the N mining areas are stably operated in series, the amount of additional leaching agent is calculated according to the leaching agent concentration requirement of the corresponding mining area and the remaining leaching agent concentration in the leaching solution of the previous mining area, and the corresponding amount of leaching agent is added by controlling the leaching agent valve.

[0019] The beneficial effects of the present invention are:

[0020] The present invention adds a certain amount of leaching agent to the leachate with a low uranium concentration and then injects it into the next mining area as the leaching solution. This method of connecting multiple mining areas in series has many advantages over the existing single mining area leaching. First, the uranium leached from multiple mining areas is superimposed together in a series manner, thereby achieving an increase in the uranium concentration of the final output leachate. Second, the remaining leaching agent in the leachate of the middle mining area is reused, which reduces the consumption of the leaching agent and makes it feasible to use a higher concentration of leaching agent to enhance the leaching of the ore. Third, the amount of leachate finally output is only a fraction of that of the normal method, and a large amount of solution does not need to be treated by hydrometallurgy, which reduces the consumption of hydrometallurgy materials, helps to reduce the construction scale of the hydrometallurgy plant, or improve the production capacity of the hydrometallurgy plant at the same scale. This method is particularly suitable for mines with a low uranium concentration in the leachate or mining areas with a low uranium concentration in the leachate in the middle and late stages of leaching. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Most of the series diagrams are adopted

[0022] Among them: 1. Liquid injection main pipe, 2. Liquid extraction main pipe, 3. Power supply cable, 4. First series pipe, 5. Second series pipe, 6-1. First liquid injection main pipe, 6-2. Second liquid injection main pipe, 6-3. Third liquid injection main pipe, 7-1. First liquid extraction main pipe, 7-2. Second liquid extraction main pipe, 7-3. Third liquid extraction main pipe, G1. First pipeline pump, G2. Second pipeline pump, Z1. Liquid injection hole of A mining area, Z2. Liquid injection hole of B mining area, Z3. Liquid injection hole of C mining area, C1. Liquid extraction hole of A mining area, C2. Liquid extraction hole of B mining area, C3. Liquid extraction hole of C mining area, R1. First valve of main pipe, R2. Second valve of main pipe, R3. Third valve of main pipe, FZ1. First valve, FZ2. Second valve, FZ3. Third valve, FC1. Fourth valve, FC2. Fifth valve, FC3. Sixth valve. DETAILED DESCRIPTION

[0023] The following is combined with Figure 1 The present invention is further described in detail with reference to the accompanying drawings and specific embodiments.

[0024] A certain in-situ uranium mine has the characteristics of low grade, large permeability and strong reducibility. It adopts acid leaching process and sulfuric acid as the leaching agent to achieve industrial mining through the "large flow and low concentration" method. The in-situ uranium mine has invested in 16 mining areas, of which more than ten mining areas currently have a leaching rate of less than 50%, and the uranium concentration of the leachate is already lower than 10 mg / L. Due to the limited processing capacity of the leachate treatment facilities, in order to maintain production capacity and control production costs, the amount of liquid pumped into the mining areas with lower efficiency has to be reduced. The reduction in the amount of liquid pumped has led to a further reduction in the production capacity of these mining areas, and the service life of the mining areas has been further extended. To solve this problem, the in-situ uranium mine adopted this technology, which significantly increased the uranium concentration of the leachate by connecting multiple mining areas in series, and achieved good economic benefits. The following is an operation example:

[0025] (1) Determine the order of series connection of mining areas; this should be determined based on the leaching stage of the mining area, the difference between the uranium concentration of the leaching solution and the concentration of the remaining leaching solution, and the geographical location of the mining area.

[0026] Considering the leaching stage of the mining area, if the mining area with a leaching rate higher than 90% of the designed leaching rate and the mining area with a leaching rate lower than 90% of the designed leaching rate exist at the same time, the mining area with a leaching rate higher than 90% of the designed leaching rate shall be in the front of the series connection.

[0027] When the differences between the uranium concentration in the leaching solution of the mining areas to be connected in series and the concentration of the remaining leaching agent are both less than or equal to 10%, the mining areas are connected in series from far to near in terms of their geographical locations.

[0028] When at least one of the uranium concentration in the leachate of the mining areas to be connected in series and the concentration of the remaining leachate is greater than 10%, the concentrations of the remaining leachate in the mining areas are compared; when the difference in the concentrations of the remaining leachate in the leachates of the mining areas to be connected in series is greater than 10%, the mining area with a higher concentration of the remaining leachate is placed in front; when the difference in the concentrations of the remaining leachate in the leachates of the mining areas to be connected in series is less than or equal to 10%, if the difference in the concentrations of uranium in the leachate between the mining areas to be connected in series is greater than 10%, the mining area with a higher concentration of uranium in the leachate is placed at the back.

[0029] According to the production situation, this technology is proposed to be used to operate the three mining areas A, B and C in the late stage of leaching in series. The main conditions of the three mining areas A, B and C are shown in Table 1. The uranium concentration of the leaching solution in the three mining areas is not much different, and the mining area A with a higher concentration of residual leaching agent is placed at the front of the series sequence. The difference between the two mining areas B and C is not big. Considering the geographical location of the three mining areas, they are connected in series in sequence, and the mining area B is determined to be in the middle of the series sequence, and the mining area C is at the end of the series sequence.

[0030] Table 1 Basic situation statistics of mining area

[0031]

[0032] (2) Connect the main pipe for extraction and injection. Generally speaking, an in-situ leaching uranium mine is equipped with a pipe network for extraction and injection, which mainly includes the injection main pipe 1 and the extraction main pipe 2 at the well site. Each mining area is provided with a liquid injection main pipe (the first liquid injection main pipe 6-1, the second liquid injection main pipe 6-2, and the third liquid injection main pipe 6-3 corresponding to the A, B, and C mining areas, respectively) and a liquid extraction main pipe (the first liquid extraction main pipe 7-1, the second liquid extraction main pipe 7-2, and the third liquid extraction main pipe 7-3 corresponding to the A, B, and C mining areas, respectively). The first liquid injection main pipe 6-1, the second liquid injection main pipe 6-2, and the third liquid injection main pipe 6-3, the first liquid extraction main pipe 7-1, the second liquid extraction main pipe 7-2, and the third liquid extraction main pipe 7-3 of the mining area are connected with the liquid main pipe 1 and the liquid extraction main pipe 2 of the well site, respectively. The first liquid injection main pipe 6-1, the second liquid injection main pipe 6-2, and the third liquid injection main pipe 6-3, the first liquid extraction main pipe 7-1, the second liquid extraction main pipe 7-2, and the third liquid extraction main pipe 7-3 of the mining area are installed with valves FZ1 first valve, FZ2 second valve, FZ3 third valve, FC1 fourth valve, FC2 fifth valve, and FC3 sixth valve.

[0033] Each mining area has a number of injection holes (the first injection hole Z1, the second injection hole Z2, and the third injection hole Z3 in the A, B, and C mining areas, respectively) and extraction holes (the first extraction hole C1, the second extraction hole C2, and the third extraction hole C3 in the A, B, and C mining areas, respectively). Each injection hole is equipped with a valve and a flow meter, and each extraction hole is equipped with a valve, a flow meter, and a deep well submersible pump. According to the above-determined A→B→C mining area series sequence, the first extraction main pipe 7-1 in the A mining area is connected to the second injection main pipe 6-2 in the B mining area through the first series pipe 4, and the second extraction main pipe 7-2 in the B mining area is connected to the third injection main pipe 6-3 in the C mining area through the second series pipe 5. Because the extraction pressure of the previous mining area does not meet the injection pressure requirements of the next mining area, the first pipeline pump G1 and the first pipeline pump G2 are installed on the first series pipe 4 and the second series pipe 5, respectively.

[0034] (3) Connect the leachate main pipe with the injection main pipe. An industrial sulfuric acid (leachate) main pipe is laid from the sulfuric acid reservoir in the leachate treatment plant to the well site. Each mining area is laid with an industrial sulfuric acid main pipe equipped with relevant flow meters and the first valve R1 of the main pipe, the first valve R2 of the main pipe, and the first valve R3 of the main pipe, which are connected to the injection main pipes 6-1, 6-2, and 6-3 of the corresponding mining area. A pipeline mixer is installed at the connection part to ensure that the industrial sulfuric acid and the leachate are evenly mixed during use.

[0035] (4) Multiple mining areas are operated in series. For ease of description, it is assumed that all valves are closed. Open all valves of the C mining area's pumping hole C3, open the third valve FC3, and start the C mining area's pumping hole C3 according to the planned pumping volume. After the operation is stable, open all valves of the C mining area's injection hole Z3, open all valves of the B mining area's pumping hole C2, start the B mining area's pumping hole C2 according to the planned pumping volume, during which the second pipeline pump G2 is started according to the pressure demand and the valve of the C mining area's injection hole Z3 is adjusted to maintain the pumping and injection balance of the C mining area. After the operation is stable, open all valves of the B mining area's injection hole Z2, open all valves of the A mining area's pumping hole C1, start the A mining area's pumping hole C1 according to the planned pumping volume, during which the first pipeline pump G1 is started according to the pressure demand and the valve of the B mining area's injection hole Z2 is adjusted to maintain the pumping and injection balance of the B mining area. After the operation is stable, open the first valve FZ1, and adjust the valve of the A mining area's injection hole Z1 to maintain the pumping and injection balance of the A mining area. After the multiple mining areas are running stably in series, take the solutions in the first injection main pipe 6-1, the first series pipe 4 and the second series pipe 5 to detect the sulfuric acid concentration therein. According to the sulfuric acid concentration requirements and injection volume of the A, B and C mining areas, calculate the amount of sulfuric acid added, and adjust the first valve, the second valve and the third valve of the industrial sulfuric acid main line to control the amount of industrial sulfuric acid added to meet the demand.

[0036] Through the above method, the three mining areas are connected in series, and the pumping volume of the A, B, and C mining areas is controlled to be 200m 3 / h、201m 3 / h、202m 3 / h, the concentration of sulfuric acid in the leaching agent was 10g / L, 7g / L, and 7g / L respectively. After 4 months of series leaching, the uranium concentration of the leachate extracted from the C mining area reached 18mg / L and was still rising. Compared with the operation of a single mining area, the three-mining area series mode increased the power consumption by 30.6% due to the increase in water volume and the presence of intermediate solution (but the power consumption was reduced by 27.3% compared with the single mining area operation mode with the same water volume), but the amount of solution delivered to the leachate treatment system was reduced by 39.5%, and the amount of uranium metal produced increased by 66.6%. After deducting the impact of the increase in power consumption, good benefits were still achieved. The improvement in benefits makes the recovery of lower levels of uranium in the leachate economically feasible, which is conducive to improving the recovery and utilization rate of uranium resources.

[0037] The above content is an explanation of a method for increasing the uranium concentration of in-situ leaching uranium leachate based on an on-site application example in a certain in-situ leaching uranium mine. Any equivalent substitutions and obvious deformations made by using a technical method of connecting multiple mining areas (units, single holes) in series are within the substantive scope of this description and should be protected by the present invention.

Claims

1. A method for increasing the uranium concentration of an in-situ leaching uranium solution, characterized in that: The following steps are involved: Step 1: Determine the order of the mining area series connection; according to the leaching stage of the mining area, the concentration of uranium in the leaching solution and the concentration difference of the remaining leaching solution, and the geographical location; Step 2: Connect the liquid extraction main pipe with the liquid injection main pipe; according to the series connection sequence of the mining areas determined in step 1, connect the liquid extraction main pipe of the previous mining area with the liquid injection main pipe of the next mining area; Step 3: Connect the leaching agent main pipe with the liquid injection main pipe; connect the leaching agent pipeline with the liquid injection main pipes of each mining area respectively. Step 4: Multiple mining areas are operated in series. According to the series order of the mining areas, open the valve connecting the last mining area's pumping main pipe with the well site's main pumping pipe, and start the submersible pumps of the pumping holes of each mining area from back to front.

2. A method for increasing the uranium concentration of in-situ leaching uranium solution according to claim 1, characterized in that: In the step 1, the number of mining areas connected in series is N, where N≥2.

3. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 2, characterized in that: In the step 1, according to the leaching stage of the mining area, if the mining area with a leaching rate higher than 90% of the designed leaching rate and the mining area with a leaching rate lower than 90% of the designed leaching rate coexist, the mining area with a leaching rate higher than 90% of the designed leaching rate is in the front of the series connection.

4. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 1, characterized in that: In the step 1, when the differences between the concentration of uranium in the leaching solution of the mining areas to be connected in series and the concentration of the remaining leaching agent are both less than or equal to 10%, the mining areas are connected in series from far to near in terms of their geographical locations.

5. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 4, characterized in that: In the step 1, when at least one of the uranium concentration in the leaching solution of the mining areas to be connected in series and the concentration of the remaining leaching solution is greater than 10%, the concentration of the remaining leaching solution of the mining areas is compared; when the difference in the concentration of the remaining leaching agent in the leaching solution of the mining areas to be connected in series is greater than 10%, the mining area with a higher concentration of the remaining leaching agent is placed in front; when the difference in the concentration of the remaining leaching agent in the leaching solution of the mining areas to be connected in series is less than or equal to 10%, the difference in the uranium concentration in the leaching solution between the mining areas to be connected in series is compared, and if the difference in the uranium concentration in the leaching solution between the mining areas to be connected in series is greater than 10%, the mining area with a higher concentration of uranium in the leaching solution is placed at the back.

6. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 1, characterized in that: In the step 2, if the pumping pressure of the previous mining area cannot meet the injection pressure requirement of the next mining area, a pipeline pump is installed on the pipeline to increase the pressure.

7. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 1, characterized in that: In the step three, a suitable mixing device is selected according to the type of the leaching agent to uniformly mix the leaching agent with the solution in the injection main pipe.

8. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 1, characterized in that: In the step four, while starting the submersible pump of the extraction hole of a certain mining area, the valve of the injection hole of the next mining area is adjusted to maintain the extraction and injection balance of the next mining area; until the submersible pump of the extraction hole of the first mining area is started, the valve connecting the injection main pipe of the first mining area and the well field injection main pipe is opened, and the valve of the injection hole of the first mining area is adjusted to maintain the extraction and injection balance of the first mining area.

9. A method for increasing the uranium concentration of in-situ leaching uranium solution as claimed in claim 1, characterized in that: In the fourth step, after the N mining areas are stably operated in series, the amount of additional leaching agent is calculated according to the leaching agent concentration requirement of the corresponding mining area and the remaining leaching agent concentration in the leaching solution of the previous mining area, and the corresponding amount of leaching agent is added by controlling the leaching agent valve.

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