A dry tailings recovery method

Abstract

This invention discloses a dry tailings dam mining method, relating to the field of tailings resource recovery technology. The method involves dividing the tailings dam into a conventional zone and a dead zone in the corners through surveying. In the dead zone, a layered, adaptable road is laid, consisting of a base layer, a bearing layer, and a surface layer. The base layer is paved with tailings sand, cement, and crushed stone, and includes drainage ditches. The bearing layer is cement-stabilized crushed stone mixed with tailings sand, incorporating anti-settlement components and a reinforcing layer. The surface layer is asphalt-stabilized crushed stone mixed with tailings sand. The road extends from the main working road to the core dead zone, with rounded transitions at corners and movable iron plates in complex areas. During mining, a layered, stepped method is used, mining first in the conventional zone and then in the dead zone, with equipment operating along the road. After mining, the road is dismantled, materials are recovered, and the site is cleaned to restore the terrain. This invention solves the problems of difficult and inefficient cleaning of dead zones and high road construction costs, achieving efficient and environmentally friendly tailings resource recovery.

Description

Technical Field

[0001] This invention relates to the field of tailings resource recovery technology, specifically a dry tailings dam recovery method. Background Technology

[0002] Tailings dams are facilities for storing tailings generated during the mineral processing process. With the increasing scarcity of mineral resources and ever-increasing environmental protection requirements, the recycling and utilization of tailings resources accumulated in tailings dams has become a key development direction for the industry. Dry mining is widely used in the mining operations of various tailings dams due to its advantages of a friendly working environment, low water consumption, and high tailings resource utilization rate.

[0003] Currently, dry tailings dam mining mainly employs mechanical excavation and vehicle transportation. However, in actual operations, the cleaning of tailings in dead corners (including corners around the tailings dam, the junction of the dam body and the dam wall, and the bottom of slopes) remains a persistent technical challenge. Existing technologies either fail to lay dedicated working roads, relying on excavation equipment to work directly on the tailings surface. Due to the narrow spaces and soft foundations of these dead corners, large excavating equipment and transport vehicles cannot enter, requiring only small equipment for slow cleaning. This not only results in extremely low mining efficiency but also easily leads to tailings collapses and equipment subsidence. Alternatively, conventional hardened roads are laid, but these have long construction cycles, high costs, and cannot be flexibly adjusted according to the mining progress. Furthermore, road demolition after mining is difficult and generates new construction waste. Additionally, conventional roads cannot extend to the core areas of these dead corners, failing to completely solve the problem of incomplete tailings cleaning in these areas.

[0004] Furthermore, in existing tailings mining methods, road construction is disconnected from mining operations, and the road's load-bearing capacity cannot meet the equipment requirements of dry mining, easily leading to road subsidence and damage, further affecting the continuity of mining operations. Simultaneously, tailings accumulate in the corners and dead zones of tailings ponds for extended periods, exhibiting uneven moisture content and complex particle size distribution. Conventional mining methods easily result in tailings residue, low recovery rates, and resource waste. Therefore, designing a road construction scheme that is adaptable to operations in corners and dead zones, flexible in adjustment, meets load-bearing capacity standards, and is cost-effective, combined with a scientific mining process, to solve the problem of difficult tailings cleanup in these corners and dead zones, has become an urgent technical requirement in the field of dry tailings dam mining. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as difficulties in cleaning tailings in corners and dead zones, low mining efficiency, incomplete mining, and unreasonable road paving, this invention provides a dry mining method for tailings ponds. By designing a specially designed, detachable, and movable layered road and matching it with a suitable mining process, this method achieves efficient and thorough cleaning of tailings in corners and dead zones, while reducing mining costs, ensuring operational safety, and improving tailings recovery rate.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a dry tailings dam mining method, characterized by comprising the following steps:

[0007] S1. Preliminary Exploration and Regional Division: A comprehensive exploration of the tailings dam will be conducted to determine its type, size, tailings accumulation thickness, and physical and mechanical properties (including particle size distribution, moisture content, and consolidation strength). The exploration will focus on the extent of corner and dead-end areas, topographic slope, foundation bearing capacity, and tailings accumulation. To improve the accuracy of the exploration, drone aerial photography combined with on-site sampling and testing will be used to accurately determine the extent of the corner and dead-end mining areas and the distribution of tailings, providing precise data support for road design and mining operations. Based on the exploration results, the tailings dam will be divided into a conventional mining area and a corner and dead-end mining area. The corner and dead-end mining area includes the tailings dam corner area, the area where the dam body connects to the dam wall, and the dead-end area at the bottom of the slope.

[0008] S2. Design and paving of dedicated roads: Considering the terrain characteristics of the corner mining area, a detachable and movable layered adaptable road is designed and laid. This layered adaptable road includes a base layer, a load-bearing layer, and a surface layer. The specific paving process is as follows:

[0009] S21. Base Course Laying: Before laying the base course, the soft tailings in the corner mining area should be pre-compacted using a light roller 2-3 times, achieving a compaction degree ≥88%. If the tailings moisture content is too high (≥23%), it should be dried first until the moisture content drops to 15%-20% before laying the base course to prevent softening and subsidence. On the surface of the tailings in the corner mining area, a mixture of tailings sand, cement, and crushed stone should be laid and compacted in layers to form the base course, with a thickness of 18-24 mm. The base course is constructed with tailings sand, cement, and crushed stone in a mass ratio of 60-70:5-8:22-35. After paving, it is compacted using a light roller with a compaction degree ≥93%. During the base course construction, a drainage ditch is installed every 1.5-2.0m along the road extension direction. A permeable pipe wrapped with geotextile is laid in the drainage ditch, with a diameter of 180-220mm. Both ends of the drainage ditch are connected to the original drainage system of the tailings dam to drain the water accumulated inside the base course and prevent the base course from softening and sinking.

[0010] S22. Load-bearing layer laying: A load-bearing layer is laid on top of the base layer. The load-bearing layer is a cement-stabilized crushed stone layer mixed with tailings sand, with a thickness of 18-30cm. The tailings sand content is 30%-40%, and the compressive strength of the cement-stabilized crushed stone is ≥3.0MPa. A fiberglass mesh reinforcement layer is laid between the load-bearing layer and the base layer to enhance the overall strength of the road and prevent road cracking and settlement. At the same time, anti-settlement components are embedded in the load-bearing layer. The anti-settlement components include a first support plate and a second support plate arranged vertically and vertically. Several reinforcing support ribs are fixed between the two support plates. The anti-settlement components are arranged one-to-one with the permeable pipes of the drainage blind ditch to further improve the load-bearing stability of the road.

[0011] S23. Surface layer laying: A surface layer is laid on the top surface of the bearing layer. The surface layer is an asphalt-stabilized crushed stone layer mixed with tailings sand, with a thickness of 12-18cm. The tailings sand content is 20%-30%. The surface layer is treated with anti-slip treatment. During the laying process, space is reserved for equipment turning to ensure that excavating equipment and transport vehicles can operate flexibly in the corner and dead area of ​​the reservoir.

[0012] S24. Road Extension and Connection: The layered adaptation road extends from the main working road in the conventional mining area to the core clearing location in the corner mining area. The road width is 4.5-5.5m, the road slope is ≤15°, and the corners are rounded with a radius ≥5m. The connection between the road and the main working road is a gradual transition with a transition length ≥10m to ensure smooth vehicle passage. For corner areas with complex terrain and extremely low foundation bearing capacity, movable iron plates with a thickness of 10-15mm are laid on the surface. These plates can be flexibly moved and disassembled according to the mining progress to further improve the road's bearing capacity and prevent equipment from sinking. At the same time, a passing platform is set every 50-80m on the layered adaptation road. The passing platform is ≥8m wide and ≥15m long to facilitate passing of transport vehicles and avoid road congestion.

[0013] S3. Dry mining operation: A layered bench mining method is adopted. First, the conventional mining area is mined, and then the excavating equipment and transport vehicles are transported to the corner mining area through the laid layered adaptable roads for operation. The specific steps are as follows:

[0014] S31. Conventional mining area mining: Tracked excavators are used for layered excavation with a layer thickness of 1.0-1.5m. The excavated tailings are transported to the designated stockpile or reprocessing workshop via the main operating road. During the mining process, the scattered tailings on the main operating road are cleared simultaneously to ensure that the road is unobstructed.

[0015] S32. Reclamation in Dead Corner Areas: Based on the terrain characteristics of dead corner areas, small tracked excavators are used in conjunction with medium-sized excavators for collaborative operation. The small excavators excavate deep into the core area of ​​the dead corner, while the medium-sized excavators transfer the excavated tailings along the layered adaptation roads. The transport vehicles then transport the tailings out along the layered adaptation roads and the main operating road. During the reclamation process, the layered excavation thickness is controlled at 0.8-1.2m, and the step slope angle is reduced to 1:3.0-1:3.5. Excavation is carried out while the tailings are transferred to prevent tailings accumulation and avoid tailings slippage. Simultaneously, drainage ditches are used to drain accumulated water from the work area in real time, keeping the roads and work surfaces dry to ensure operational safety and efficiency. During reclamation operations, guardrails are installed on both sides of the layered adaptation roads. The guardrails are ≥1.2m high and have a detachable structure to prevent tailings from rolling onto the road and affecting traffic, while also protecting the safety of workers.

[0016] S33. Adjustment of mining: According to the mining progress, gradually dismantle and move the movable iron plates and part of the surface and bearing layer in the corner mining area, and gradually extend the road to the unmined corner area to ensure that the road always covers the area to be mined, until all tailings in the corner mining area are cleared.

[0017] S4. Road Recycling and Site Cleanup: After all tailings in the dead-end mining area and the conventional mining area are recovered, the layered and adapted roads are dismantled and recycled. The asphalt-stabilized crushed stone and cement-stabilized crushed stone of the surface and load-bearing layers are crushed into particles with a particle size of ≤50mm using crushing equipment, which can be reused as base material for road paving, realizing resource recycling and reducing mining costs. The tailings sand of the base layer is directly recycled and reused, and can be cleaned with movable iron plates and recycled for later use. At the same time, the scattered tailings and road residues in the mining area are cleaned up, the site is leveled, the original topography of the tailings pond is restored, and environmental pollution is avoided.

[0018] Compared with existing technologies, the present invention provides a dry tailings dam mining method, which has the following advantages:

[0019] 1. This invention designs a dedicated layered adaptable road that extends from the conventional mining area to the core area of ​​the reservoir corner and dead zone. Combined with the flexible adaptability of movable iron plates, it enables excavating equipment and transport vehicles to smoothly enter the reservoir corner and dead zone area for operation. This completely changes the existing situation where large equipment cannot enter the reservoir corner and dead zone and the cleaning is not thorough. The tailings recovery rate of the reservoir corner and dead zone is increased to more than 98%, avoiding resource waste.

[0020] 2. The layered adaptable road adopts a "base layer + load-bearing layer + surface layer" structure, combined with the resource utilization of tailings sand. This not only ensures the road's load-bearing capacity and adapts to the excavation equipment and transport vehicles used in dry mining, but also reduces road paving costs. At the same time, the road is disassembled and movable, and its extension direction can be flexibly adjusted according to the mining progress. It can adapt to the corners and dead angles of different terrains, making it highly practical. Moreover, the road materials are recyclable and reusable, which is in line with the concept of green environmental protection. It avoids the construction waste pollution problem generated after the demolition of conventional hardened roads and realizes the dual recycling of tailings resources and road materials.

[0021] 3. By using a layered, stepped mining method, combined with drainage ditches and pre-compaction treatment on the road, the safety hazards such as equipment sinking and tailings collapse caused by soft tailings and uneven moisture content are effectively solved, ensuring continuous mining operations. Small and medium-sized excavators are used in conjunction with each other in the corners of the reservoir, which greatly improves mining efficiency. Compared with existing technologies, the mining efficiency of tailings in corners of the reservoir is increased by more than 50%, and the overall mining cycle is shortened by more than 30%.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0024] Figure 1 This is a schematic diagram of the tailings dam mining area division and road paving in this invention;

[0025] Figure 2 This is a schematic cross-sectional view of the layered adaptive road structure in this invention. Detailed Implementation

[0026] Please combine Figures 1 to 2 As shown, this invention provides a dry tailings dam mining method applied to a hillside tailings dam. This tailings dam has many dead corners, mainly including three corner areas and two areas where the dam body connects to the dam wall. The tailings accumulation thickness in the dead corners is 2.5-4.0m, and the tailings are mainly fine-grained with a moisture content of 18%-22%. The foundation bearing capacity is low. The specific steps are as follows:

[0027] S1. Preliminary Exploration and Area Delineation: A comprehensive survey of the tailings dam was conducted using drone aerial photography combined with on-site sampling and testing. The tailings dam dimensions were determined to be 300m long and 150m wide, with an average tailings accumulation thickness of 3.2m. The tailings particle size distribution showed that -200 mesh fine particles accounted for 65%, and the consolidation strength was 0.8MPa. A conventional mining area (38,000㎡) and a corner mining area (7,000㎡) were delineated, specifying the exact boundaries and terrain slope (maximum slope 18°) of the corner mining area.

[0028] S2, Design and paving of dedicated roads:

[0029] S21. Base course laying: The soft tailings in the corner mining area of ​​the tailings pond are pre-compacted by rolling three times with a light roller to achieve a compaction degree of 89%. The base course is formed by layering and compacting tailings sand, cement, and crushed stone in a mass ratio of 65:6:29. The base course is 20cm thick and is compacted with a light roller to achieve a compaction degree of 94%. A drainage ditch is set every 1.8m along the road extension direction. A permeable pipe (200mm in diameter) wrapped with geotextile is laid in the drainage ditch. The two ends of the drainage ditch are connected to the original drainage system of the tailings pond.

[0030] S22. Load-bearing layer laying: A cement-stabilized crushed stone layer mixed with tailings sand is laid on the top surface of the base layer as a load-bearing layer with a thickness of 24cm, a tailings sand content of 35%, and a compressive strength of 3.2MPa for the cement-stabilized crushed stone. A fiberglass mesh reinforcement layer is laid between the load-bearing layer and the base layer. At the same time, anti-settlement components are embedded in the load-bearing layer. The anti-settlement components include a first support plate and a second support plate that are set up vertically and vertically. Four reinforcing support bars are fixed between the two support plates. The anti-settlement components are set up one-to-one with the permeable pipes.

[0031] S23. Surface layer laying: A 15cm thick asphalt-stabilized crushed stone layer mixed with tailings sand is laid on the top surface of the bearing layer. The tailings sand content is 25%. The surface layer is treated with anti-slip treatment and space is reserved for equipment turning.

[0032] S24. Road Extension and Connection: The layered adaptive road extends from the main working road in the conventional mining area to the core clearing location in the corner mining area. The road width is 5.0m, the road slope is controlled at 12°, and the corners are rounded with a radius of 6m. The connection between the road and the main working road is a gradual transition with a transition length of 12m. In the corner mining area with the most complex terrain and the lowest foundation bearing capacity, a movable iron plate with a thickness of 12mm is laid on the surface. A passing platform is set every 60m on the road, with a width of 8m and a length of 15m.

[0033] S3, Dry mining operation:

[0034] S31, conventional mining area mining: tracked excavators are used for layered excavation with a layer thickness of 1.2m. The excavated tailings are transported to the reprocessing workshop through the main operating road. During the mining process, the scattered tailings on the main operating road are cleaned up simultaneously.

[0035] S32. Reclamation of Dead Corner Area: Small tracked excavators (0.8m³ bucket capacity) and medium-sized excavators (1.5m³ bucket capacity) work together. The small excavator goes deep into the core area of ​​the dead corner for excavation, while the medium-sized excavator transports the tailings along the layered adaptation road. The excavated tailings are transferred to transport vehicles (15t load capacity), which then transport the tailings out along the layered adaptation road and the main working road. During the reclamation process, the layered excavation thickness is controlled at 1.0m, the step slope angle is reduced to 1:3.2, and the excavation is carried out while the vehicle is being moved to prevent tailings from accumulating. Drainage blind ditches are used to drain water from the working area in real time to keep the roads and working surfaces dry. Detachable guardrails with a height of 1.2m are installed on both sides of the layered adaptation road.

[0036] S33. Adjustment of mining: According to the mining progress, gradually dismantle and move the movable iron plates and part of the surface and bearing layer in the corner mining area, and gradually extend the road to the unmined corner area to ensure that the road always covers the area to be mined;

[0037] S4. Road Recycling and Site Cleanup: After all tailings in the corner and conventional mining areas are recovered, the layered roads are dismantled and recycled. The surface and bearing layers are crushed into particles with a diameter of ≤50mm using crushing equipment for use as base material for subsequent road paving. The tailings sand in the base layer is directly recycled and reused, and movable iron plates are cleaned and recycled for later use. Scattered tailings and road residues in the mining area are cleaned up, the site is leveled, and the original topography of the tailings dam is restored.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the accompanying drawings and the above description. However, any modifications, alterations, or variations made by those skilled in the art without departing from the scope of the present invention, utilizing the disclosed technical content, are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A dry tailings dam mining method, characterized in that, Includes the following steps: S1. Preliminary Exploration and Regional Division: Conduct a comprehensive exploration of the tailings dam to clarify its type, size, tailings accumulation thickness, and physical and mechanical properties. Focus on the extent, topographic slope, foundation bearing capacity, and tailings accumulation of the dead corner areas. Based on the exploration results, the tailings dam will be divided into a conventional mining area and a dead corner mining area. The dead corner mining area includes the corner areas of the tailings dam, the area where the dam body connects to the dam wall, and the dead corner area at the bottom of the slope. S2. Design and paving of dedicated roads: Considering the terrain characteristics of the corner mining area, a detachable and movable layered adaptable road is designed and laid. This layered adaptable road includes a base layer, a load-bearing layer, and a surface layer. The specific paving process is as follows: S21. Base course laying: On the surface of the tailings in the dead corner mining area of ​​the tailings, the tailings sand mixed with cement and crushed stone is spread and compacted in layers to form the base course. The thickness of the base course is 18-24cm. The mass ratio of tailings sand, cement and crushed stone is 60-70:5-8:22-35. After spreading, it is compacted with a light roller to achieve a compaction degree of ≥93%. During the base course laying process, a drainage ditch is set every 1.5-2.0m along the road extension direction. A permeable pipe wrapped with geotextile is laid in the drainage ditch. The diameter of the permeable pipe is 180-220mm. Both ends of the drainage ditch are connected to the original drainage system of the tailings dam. S22. Load-bearing layer laying: A load-bearing layer is laid on the top surface of the base layer. The load-bearing layer is a cement-stabilized crushed stone layer mixed with tailings sand, with a thickness of 18-30cm. The tailings sand content is 30%-40%, and the compressive strength of the cement-stabilized crushed stone is ≥3.0MPa. A fiberglass mesh reinforcement layer is laid between the load-bearing layer and the base layer. At the same time, an anti-settlement component is embedded in the load-bearing layer. The anti-settlement component includes a first support plate and a second support plate that are arranged vertically and vertically. Several reinforcing support ribs are fixed between the two support plates. The anti-settlement component is arranged one-to-one with the permeable pipe of the drainage blind ditch. S23. Surface layer laying: A surface layer is laid on the top surface of the load-bearing layer. The surface layer is an asphalt-stabilized crushed stone layer mixed with tailings sand, with a thickness of 12-18cm. The tailings sand content is 20%-30%. The surface layer is treated with anti-slip treatment. Space is reserved for equipment turning during the laying process. S24. Road Extension and Connection: The layered adaptive road extends from the main working road in the conventional mining area to the core clearing location in the corner mining area. The road width is 4.5-5.5m, the road slope is ≤15°, and the corners are rounded with a radius ≥5m. The connection between the road and the main working road is a gradual transition with a transition length ≥10m. For the corner mining area with complex terrain and extremely low foundation bearing capacity, a movable iron plate with a thickness of 10-15mm is laid on the surface. S3. Dry mining operation: adopts a layered step mining method. First, the conventional mining area is mined, and then the excavation equipment and transport vehicles are transported to the corner mining area of ​​the reservoir through the laid layered adaptable roads for operation. S4. Road Recycling and Site Cleanup: After all tailings in the dead corner mining area and the conventional mining area are recycled, the layered and adapted roads are dismantled and recycled. The asphalt-stabilized crushed stone and cement-stabilized crushed stone of the surface and bearing layers can be reused for road paving or tailings reprocessing. The tailings sand of the base layer is directly recycled and reused. The movable iron plate is cleaned and recycled for later use. At the same time, the scattered tailings and road residues in the mining area are cleaned up, the site is leveled, and the original topography of the tailings dam is restored.

2. The dry tailings dam mining method according to claim 1, characterized in that: In step S1, an aerial survey is conducted using drones combined with on-site sampling and testing to accurately determine the extent of the dead-end mining area and the distribution of tailings.

3. The dry tailings dam mining method according to claim 1, characterized in that: In step S21, before laying the base course, the soft tailings in the corner mining area are pre-compacted by using a light roller to compact the tailings 2-3 times, with a compaction degree ≥88%. If the moisture content of the tailings is ≥23%, they are dried first, and the base course is laid after the moisture content drops to 15%-20%.

4. The dry tailings dam mining method according to claim 1, characterized in that: In step S24, a meeting platform is set up every 50-80m on the layered adaptation road, with a width of ≥8m and a length of ≥15m for each meeting platform.

5. The dry tailings dam mining method according to claim 1, characterized in that: In step S3, the dry mining operation specifically includes the following steps: S31. Conventional mining area mining: Tracked excavators are used for layered excavation with a layer thickness of 1.0-1.5m. The excavated tailings are transported to the designated stockpile or reprocessing workshop via the main operating road. During the mining process, the scattered tailings on the main operating road are cleaned up simultaneously. S32. Reclamation of Dead Corner Area: Small tracked excavators are used in conjunction with medium-sized excavators for collaborative operation. The small excavators excavate deep into the core area of ​​the dead corner, while the medium-sized excavators transfer the excavated tailings along the layered adaptation road. The transport vehicles then transport the tailings out along the layered adaptation road and the main working road. During the reclamation process, the layered excavation thickness is controlled at 0.8-1.2m, and the step slope angle is reduced to 1:3.0-1:3.

5. The excavation is carried out while the tailings are being moved, and tailings are not piled up. At the same time, drainage blind ditches are used to drain water from the working area in real time. S33. Adjustment of mining: According to the mining progress, gradually dismantle and move the movable iron plates and part of the surface and bearing layers in the corner mining area, and gradually extend the road to the unmined corner area until all tailings in the corner are cleared.

6. The dry tailings dam mining method according to claim 1, characterized in that: In step S32, during the mining operation, guardrails are installed on both sides of the layered adaptation road. The guardrails are ≥1.2m high and have a detachable structure.

7. The dry tailings dam mining method according to claim 1, characterized in that: In step S4, the asphalt-stabilized crushed stone and cement-stabilized crushed stone of the surface layer and the bearing layer are crushed into particles with a particle size of ≤50mm using crushing equipment, which are then used as base materials for subsequent road paving.

8. A dry tailings dam mining method according to claim 1, characterized in that: The physical and mechanical properties of the tailings include particle size distribution, moisture content, and consolidation strength.

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