Drop-leaching liquid distribution method for uranium ore dump leaching in arid region

Abstract

The invention discloses a dripping liquid distribution method for uranium ore dump leaching in an arid region, and belongs to the technical field of uranium mining and metallurgy. The dripping liquid distribution method comprises the following steps: determining the row spacing and the spacing of drippers through an indoor experiment; a drop-leaching network comprising a main pipeline, a branch pipeline, drop-leaching branch pipes and an anti-blocking tail pipe is arranged on the top and the side slope of the ore heap; a variable-frequency pump is used for conveying leaching liquid and cooperates with a butterfly valve and a pressure control valve to regulate and control pressure; sediment is discharged through the anti-blocking tail pipe regularly, and back flushing is carried out to prevent blocking; and monitoring the liquid distribution uniformity and adjusting parameters by using infrared thermal imaging of the unmanned aerial vehicle. The method has the advantages of uniform liquid distribution, water loss as low as 4.7%, water saving, high efficiency, stable system operation, low dripper blockage risk and uranium leaching rate of over 80%, and is suitable for large-scale uranium ore dump leaching operation in drought, high-temperature and intense evaporation regions.

Description

Technical Field

[0001] This invention relates to the field of uranium mining and metallurgy, and in particular to a drip leaching method for heap leaching of uranium ore in arid regions. Background Technology

[0002] The recovery of low-grade hard-rock uranium resources typically employs heap leaching, which offers advantages such as low energy consumption, minimal infrastructure investment, and low production costs. This technology was long the primary process for mining hard-rock uranium deposits in southern my country, making significant contributions to the development and utilization of my country's uranium resources. Over more than forty years of production practice, heap leaching technology has continuously improved, developing key technologies such as microwave-assisted heap leaching, microwave-assisted crushing, and intermittent alternating spray devices and processes. It has also given rise to various process pathways, including granulation heap leaching, microbial heap leaching, and concentrated acid ripening-high-iron spray heap leaching. These technologies have demonstrated good leaching effects in practical applications, tailored to different mine conditions. For example, a uranium mine in southern my country achieved a uranium leaching rate of 80%–90% using heap leaching technology, significantly improving the recovery efficiency of low-grade uranium resources. Heap leaching is also considered an important technological reserve for the future development of deep uranium resources in southern my country.

[0003] my country's uranium heap leaching technology was primarily developed based on the unique geological and environmental conditions of uranium mines in southern China. It is more suitable for areas with smaller deposits, dispersed ore bodies, lower grades, and humid climates with abundant water resources. When extending this technology to other types of uranium mines, the technical solutions need to be optimized and adjusted according to the geological characteristics and climatic conditions of different regions. For example, when applying heap leaching technology to the Husab uranium mine located in the Namib Desert, the traditional heap leaching process faces severe challenges in terms of water resource utilization efficiency, uniform solution distribution, and operating cost control due to the mine's large reserves, large-scale heap leaching operation, and its location in an arid region with high evaporation rates and extremely scarce water resources. Targeted technological improvements and innovations are urgently needed.

[0004] Husab Uranium Mine is currently the world's second-largest uranium mine, using open-pit mining methods with a designed annual ore yield of 15 million tons, of which low-grade uranium ore accounts for about one-third of the total. To achieve efficient resource utilization, this portion of low-grade ore is being leached using heap leaching. Due to the massive production volume, the heaps are large in area and height, with a single heap containing up to 10 times the ore volume of conventional heap leaching projects in China. Furthermore, Husab Uranium Mine is located in the Namib Desert region, with temperatures ranging from 18°C ​​to 40°C, an arid climate with scarce rainfall, and an average annual evaporation rate as high as 2551 mm. Water use relies primarily on seawater desalination, resulting in high costs. Against this backdrop, how to achieve uniform leaching distribution within the heap while maximizing water conservation, reducing water costs, and ensuring good leaching efficiency has become a critical technical challenge that urgently needs to be overcome. Existing heap leaching technologies are clearly insufficient to meet the requirements of this unique application scenario. Summary of the Invention

[0005] The purpose of this invention is to provide a drip leaching method for heap leaching of uranium ore in arid areas. This method has the advantages of uniform leaching, stable operation, water saving and high efficiency, and significantly reduces the consumption of water resources and reagents. It is particularly suitable for heap leaching operations in arid, high-temperature and highly evaporative regions.

[0006] To achieve the above objectives, the present invention provides a drip leaching method for heap leaching of uranium ore in arid areas, comprising the following steps:

[0007] S1. Determine the spacing and pitch of the drippers: The wetting diameter of a single dripper is determined under different dripping intensities through indoor single-hole dripping experiments. Based on the wetting diameter, the spacing and pitch of the drippers in the stockyard are designed and determined.

[0008] S2. Laying out a drip irrigation network: Laying out a drip irrigation network on the top of the mine pile and the surrounding slopes. The drip irrigation network includes a main pipeline, branch pipelines, drip irrigation branch pipes and anti-clogging tail pipes to ensure that the drippers are evenly distributed and fully covered.

[0009] S3. Implement drip irrigation operation: Use a variable frequency pump to deliver the leaching solution to the main pipeline. A butterfly valve and a pressure control valve are installed at the connection between the main pipeline and the branch pipeline. The opening and closing of the pipeline is controlled by the butterfly valve. The drip irrigation pressure of the system is regulated and stabilized by the coordinated work of the variable frequency pump and the pressure control valve.

[0010] S4. Prevent drip hole clogging: During drip irrigation, periodically open the valve at the end of the anti-clogging tailpipe to drain the sediment in the pipe, and backwash through the anti-clogging tailpipe connected to the main pipe to reduce the risk of drip head clogging;

[0011] S5. Detection and control of liquid distribution uniformity: During the dripping process, the uniformity of liquid distribution on the pile surface is monitored regularly, and the liquid distribution parameters are adjusted based on the monitoring results to ensure uniform liquid distribution.

[0012] Preferably, the dripper placement density in step S1 is optimized and determined based on the results of indoor single-hole dripping experiments, so that the wetting range within the designed liquid distribution intensity range completely covers the surface of the stockpile.

[0013] Preferably, the main pipeline in step S2 is made of high-density polyethylene; the branch pipeline is a quick-connect flat pipe; and the dripper of the dripping branch pipe is a pressure-compensated dripper.

[0014] Preferably, in step S2, for large-area stockpiles, the main pipeline is divided into two or more parallel main pipelines at the top of the stockpile to achieve zoned liquid distribution. Each parallel main pipeline is connected to the corresponding branch pipeline through a butterfly valve and a pressure control valve.

[0015] Preferably, in step S2, the branch pipe is connected to the drip branch pipe through a threaded interface, and the spacing of the threaded interface is the same as the spacing of the drip head.

[0016] Preferably, in step S2, the drip irrigation branch pipes are arranged radially at the four corners of the ore pile, and the pressure-compensating drippers are laid with the drip holes facing downwards.

[0017] Preferably, in step S3, the drip pressure of the pipeline is precisely controlled by the coordinated operation of the variable frequency pump and the pressure control valve to ensure stable liquid distribution pressure.

[0018] Preferably, the anti-clogging tailpipe described in step S4 is connected to the end of the drip branch pipe on the same side and laid at the bottom of the storage yard. The anti-clogging tailpipe valve is opened regularly every week to discharge the sediment in the pipe and connect to the main pipeline for backwashing.

[0019] Preferably, in step S5, an airborne intelligent infrared thermal imager from a drone is used to monitor the temperature distribution on the surface of the ore pile, and the uniformity of liquid distribution is evaluated based on the temperature data, and the liquid distribution parameters are adjusted.

[0020] Therefore, the present invention employs the above-mentioned drip leaching method for heap leaching of uranium ore in arid areas, which has the following technical advantages:

[0021] (1) The present invention can achieve uniform liquid distribution on the top and slope of the ore pile, and the liquid distribution intensity can be flexibly adjusted as needed;

[0022] (2) The dripping pressure of the present invention is stable, which can effectively avoid the problems of liquid accumulation on the top of the pile and blockage of the drip holes; the anti-clogging tail pipe effectively improves the reliability of system operation;

[0023] (3) The present invention significantly reduces water evaporation loss and achieves stable operation over a long period of time.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a top view schematic diagram of the ore pile pipeline layout for a drip leaching method for uranium ore pile leaching in arid areas according to the present invention.

[0026] Figure 2 This is a schematic diagram of the wetting range of the dripping mesh in a dripping leaching method for uranium heap leaching in arid areas according to the present invention.

[0027] Figure 3 This is a particle size distribution diagram of the ore pile in a drip leaching method for uranium ore heap leaching in arid areas according to the present invention.

[0028] Figure 4 This invention relates to a drip leaching method for uranium ore heap leaching in arid areas, which involves sampling and testing the moisture content at different depths from the slope during the heap drip leaching process.

[0029] Figure 5This invention relates to a drip leaching method for uranium ore heap leaching in arid areas, which involves sampling and testing the moisture content at different depths from the top center during the heap drip leaching process.

[0030] Figure 6 This is a graph showing the uranium concentration variation in the leaching solution of a 30,000-ton heap ore using a drip-leaching method for heap leaching uranium ore in arid regions, according to the present invention.

[0031] Figure Labels

[0032] 1. Top of ore pile; 2. Bottom of ore pile; 3. Main pipeline; 4. Branch pipeline; 5. Drip branch pipe; 6. Anti-clogging tailpipe; 7. Pressure control valve; 8. Butterfly valve; 9. Valve. Detailed Implementation

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0035] A drip leaching method for heap leaching of uranium ore in arid areas includes the following steps:

[0036] S1. Determine the dripper spacing and interval.

[0037] A single-hole dripping laboratory experiment was conducted using ore samples identical to those used in the on-site uranium ore pile. The results showed that when the dripping intensity was 2.7–4.2 L / h, the radius of the resulting wetting zone was approximately 0.25–0.3 m. Using a dripper with a rated dripping intensity of 3 L / h, within the experimental dripping intensity range, the horizontal radius of the corresponding stable wetting zone was 0.25–0.3 m. When the dripper spacing was set to 0.4 m, a wetting coverage diagram drawn with this radius was obtained, as shown below. Figure 2 As shown, it can achieve full coverage of the horizontal wetting range, so the spacing and spacing of the drippers are determined to be 0.4m.

[0038] S2. Laying out the drip irrigation network

[0039] The stockpile is designed with the following dimensions: bottom section 2 measures 63m x 63m, top section 1 measures 40m x 40m, height 9m, and slope gradient 38°. The particle size distribution of uranium ore in the stockpile is shown in [reference needed]. Figure 3 The bulk density is approximately 2.5 t / m³. 3 The porosity is approximately 35.39%.

[0040] like Figure 1 As shown, the main pipeline 3 leads to the top of the ore pile 1. The main pipeline 3 is a high-density polyethylene pipe with an inner diameter of 160mm and a wall thickness of 10mm. Given the large area of ​​the stockpile, the main pipeline 3 is split into two at the top of the ore pile 1, with each branch pipeline 4 connected to a butterfly valve 8 and a pressure control valve 7. The branch pipelines 4 are 3-inch quick-connect flat pipes with a 1 / 2-inch threaded interface every 0.4m. Drip irrigation branch pipes 5 are connected to the branch pipelines 4 via threaded interfaces, extending from the top of the ore pile 1 along the slope to the bottom of the ore pile 2, arranged radially at the four corners of the ore pile. The drip irrigation branch pipes 5 are pressure-compensated drip irrigation pipes with a rated drip rate of 3L / h, an outer diameter of 16mm, an inner diameter of 14.2mm, a drip hole diameter of 2.55mm, and a spacing of 0.4m. During installation, the drip holes face downwards to achieve uniform coverage of the pile surface at 0.4m × 0.4m intervals. The ends of the drip irrigation branch pipes 5 in the same area are uniformly connected to the anti-blocking tailpipe 6 laid at the bottom of the mine pile 2. The tailpipe model is the same as that of the branch pipe 4, and valves 9 are installed at both ends.

[0041] S3. Implement drip irrigation operation

[0042] Prepare a leaching solution with a sulfuric acid concentration ranging from 10 to 100 g / L and a 5% hydrogen peroxide concentration as the oxidant. The leaching solution is then transported to the top of the ore pile 1 via a float pump and main pipeline 3, with a float pump flow rate of 80 m³ / h. 3 The system has a head of 68m and a main power of 37kW, and is equipped with a frequency converter. Zoned control is achieved by controlling the start and stop of branch pipe 4 via butterfly valve 8. The system pressure is regulated by pressure control valve 7 to stabilize it within the 8-20 meter head pressure range. The leaching solution is transported to the drip branch pipe 5 via main pipe 3 and branch pipe 4, and then dispensed through drip holes at a rate of 17-25 L / (h·m). 2 The intensity of the drip is uniform. Due to the use of pressure-compensated drip pipes, even when there is a height difference between the top of the ore pile and the slope, the flow rate can still be balanced, ensuring uniform liquid distribution intensity.

[0043] S4. Prevent drip hole clogging

[0044] During system operation, the anti-clogging tailpipe 6 valve 9 is opened weekly to drain the sediment in the drip branch pipe 5, and the anti-clogging tailpipe 6 is connected to the main pipe 3 for backflushing to prevent sediment from entering the drip holes. Temporary drainage and backflushing are performed in case of abnormal liquid distribution.

[0045] S5. Detection and control of liquid distribution uniformity

[0046] An airborne intelligent infrared thermal imager on a drone was used to detect the temperature distribution at the top of the ore pile. Based on this, the uniformity of the leaching solution distribution was analyzed, and the solution distribution parameters, such as the pipe spacing and drip intensity, were adjusted in a timely manner to achieve uniform solution distribution.

[0047] During the stable leachate operation, samples were taken along the depth direction at the ore pile slope and the middle of the top 1 of the ore pile to determine the moisture content at different depths. The test results are as follows: Figure 4 and Figure 5 As shown, the results indicate that the moisture content is between 8% and 13%. The moisture content at each depth on the slope is slightly lower than that at the corresponding depth at the top of the ore pile, and the overall moisture content shows a slight decreasing trend with increasing depth. However, the average difference is controlled within 2 percentage points, indicating that the overall moisture content distribution of the ore pile at different locations and depths is relatively uniform and the liquid distribution is good.

[0048] According to annual operational statistics, the total input volume of the leaching solution for this drip leaching method is 56298 m³. 3 The total volume of leachate collected was 53,649 m³, with a calculated water loss of 2,649 m³, representing approximately 4.7%. This indicates that under the drip irrigation system described in this invention, the water evaporation rate during the leaching cycle is controlled within 4.7%. Considering the average annual evaporation rate of 2,551 mm / a in this region, the maximum theoretical annual evaporation rate for a 63m × 63m area is approximately 10,125 m³. 3 This further verifies the significant advantages of this system in controlling water evaporation.

[0049] During the experiment, the pH value of the leaching solution remained stable at around 1.8, and the trend of uranium concentration change over time was as follows: Figure 6 As shown in the figure. The results indicate that the changes in pH value and uranium concentration were within a reasonable range, suggesting that the dripping process was stable and the chemical environment was suitable for uranium leaching.

[0050] The final liquid leaching rate exceeded 80%, which fully demonstrates that good uranium recovery and leaching efficiency can still be guaranteed under the premise of controlling evaporation and saving reagents.

[0051] Comparing the liquid accumulation at the top of the ore pile 1 during the liquid distribution process of conventional spraying systems and the dripping system of the present invention, it is clear that the dripping method of the present invention has greater advantages in terms of liquid distribution uniformity and drainage performance.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A drip leaching method for heap leaching of uranium ore in arid areas, characterized in that, Includes the following steps: S1. Determine the spacing and pitch of the drippers: The wetting diameter of a single dripper is determined under different dripping intensities through indoor single-hole dripping experiments. Based on the wetting diameter, the spacing and pitch of the drippers in the stockyard are designed and determined. S2. Laying out a drip irrigation network: Laying out a drip irrigation network on the top of the mine pile and the surrounding slopes. The drip irrigation network includes a main pipeline, branch pipelines, drip irrigation branch pipes and anti-clogging tail pipes to ensure that the drippers are evenly distributed and fully covered. S3. Implement drip irrigation operation: Use a variable frequency pump to deliver the leaching solution to the main pipeline. A butterfly valve and a pressure control valve are installed at the connection between the main pipeline and the branch pipeline. The opening and closing of the pipeline is controlled by the butterfly valve. The drip irrigation pressure of the system is regulated and stabilized by the coordinated work of the variable frequency pump and the pressure control valve. S4. Prevent drip hole clogging: During drip irrigation, periodically open the valve at the end of the anti-clogging tailpipe to drain the sediment in the pipe, and backwash through the anti-clogging tailpipe connected to the main pipe to reduce the risk of drip head clogging; S5. Detection and control of liquid distribution uniformity: During the dripping process, the uniformity of liquid distribution on the pile surface is monitored regularly, and the liquid distribution parameters are adjusted based on the monitoring results to ensure uniform liquid distribution.

2. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: The dripper placement density in step S1 is optimized and determined based on the results of indoor single-hole dripping experiments, so that the wetting range within the designed liquid distribution intensity range completely covers the surface of the stockpile.

3. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: In step S2, the main pipeline is made of high-density polyethylene; the branch pipeline is a quick-connect flat pipe; and the dripper of the dripping branch pipe is a pressure-compensated dripper.

4. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: In step S2, for large-area stockpiles, the main pipeline is divided into two or more parallel main pipelines at the top of the stockpile to achieve zoned liquid distribution. Each parallel main pipeline is connected to the corresponding branch pipeline through a butterfly valve and a pressure control valve.

5. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: The branch pipe mentioned in step S2 is connected to the drip branch pipe through a threaded interface, and the spacing of the threaded interface is the same as the spacing of the drip head.

6. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: In step S2, the drip irrigation branch pipes are arranged radially at the four corners of the ore pile, and the pressure-compensating drippers are laid with the drip holes facing downwards.

7. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: In step S3, the drip pressure of the pipeline is precisely controlled by the coordinated operation of the variable frequency pump and the pressure control valve to ensure stable liquid distribution pressure.

8. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: The anti-clogging tailpipe mentioned in step S4 is connected to the end of the drip branch pipe on the same side and laid at the bottom of the storage yard. The anti-clogging tailpipe valve is opened regularly every week to discharge the sediment in the pipe and connect to the main pipeline for backwashing.

9. The drip leaching method for heap leaching of uranium ore in arid areas according to claim 1, characterized in that: In step S5, an airborne intelligent infrared thermal imager from an unmanned aerial vehicle is used to monitor the temperature distribution on the surface of the ore pile, and the uniformity of liquid distribution is evaluated based on the temperature data, and the liquid distribution parameters are adjusted.

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