A method for closure and partition disposal of tailings pond

Abstract

The present invention introduces a zoning disposal method for tailings pond closure, which divides the beach surface into coarse sand area, soft beach area, and clear area-water area at the tail of the reservoir in sequence from the front of the dam body to the tail of the reservoir. The disposal method of the present invention can quickly and safely complete the reinforcement disposal of the soft beach of the tailings pond, complete the closure of the reservoir surface within a specified time, and provide a high-bearing capacity, low-compressibility, and low-water content working platform for subsequent greening after the closure of the reservoir; and for the tailings pond that still uses the original drainage well at the tail of the reservoir to discharge floodwater after closure, it not only effectively guarantees the progress, quality and process safety of the closure of the soft beach, but also ensures that the overall slope of the beach surface after closure is consistent with the design, which is beneficial to flood control and flood discharge safety after closure, and greatly reduces the consumption of closure covering soil.

Description

Technical Field

[0001] The invention relates to the technical field of tailings pond closure, and in particular to a tailings pond closure and partition disposal method. Background Art

[0002] Tailings ponds are used to store large amounts of waste rock, slag, wastewater and other waste generated during the mining process. As one of the three major controlling projects in a mine, it is a man-made debris flow hazard source with high potential energy and poses a risk of dam breach. Therefore, whether the tailings pond can operate normally is not only related to the economic benefits of the mining enterprise, but also affects the safety of life and property of residents downstream of the reservoir area and the stability of the surrounding ecological environment.

[0003] Relevant national standards stipulate that tailings ponds that have reached the final design stacking elevation and are no longer being raised or expanded, or that have stopped using prematurely due to various reasons and have not reached the final design stacking elevation, should be designed for closure and must be closed within 1 or 1.5 years. Normally, the first step in closing a tailings pond is to treat the beach in the reservoir area to meet the bearing capacity requirements for machinery and personnel entering the site, and then carry out soil covering, greening and other engineering repair work. Therefore, it is particularly important to solidify the beach in the reservoir area or increase its bearing capacity. Generally, wet-drainage tailings ponds that are closed have the characteristics of large reservoir area, high fine particle content, and large sediment thickness, especially the tailings in the tail storage area are large. Most of them are fluid silty clay or clay, with a series of characteristics such as high water content, poor permeability, low consolidation strength, high compression performance, low bearing capacity, difficulty in dissipating excess pore water pressure and high thixotropy; after the tailings are discharged, if the beach tailings are only naturally consolidated and the bearing capacity requirements for mechanical equipment to enter the construction are to be met, it will take a long time, especially for the tailings silty clay or tailings clay at the tail of the reservoir. It usually takes about 2 years to reach the conditions for mechanical equipment to enter, and it cannot meet the requirements of the specification to complete the closure project within 1 year or 1.5 years; if the reservoir is to be closed forcibly within the specified time, the usual methods are to directly cover the beach with soil, dump stones to squeeze out silt, or first load pre-pressure drainage and consolidation before covering with soil.

[0004] However, when the wet beach is large, reaching more than 10,000 square meters, the tailings in the tailings mud are too fine and have a high water content, but the water will not seep out at all. Pumping out the water from the tailings has no effect, which brings great difficulty to the construction. At the same time, the wet beach has no bearing capacity. A large number of stones used for squeezing silt slide into the lower part of the tailings without any effect. During the stone throwing process, the area around the drainage well at the tail of the reservoir rises significantly. Excessive or uneven stone throwing may cause the drainage well to rise more than expected, and may also cause uneven force around the derrick, which is not conducive to the stability of the derrick structure. Direct covering often causes serious extrusion deformation, uneven settlement, vibration liquefaction, and slurry overflow, resulting in an uneven beach surface and a geometric increase in the consumption of covering soil, which seriously affects the progress and quality of the closed reservoir covering construction. At the same time, due to the weak beach surface, the bonding condition between the soil and the dry tailings beach surface after mechanical covering is not ideal, and a good composite soil cannot be formed, which is not conducive to the growth of reclaimed vegetation on it, nor to the consolidation and stability of the tailings dam shell layer; the riprap method has an obvious effect within the dry beach range, but for the soft beach area at the tail of the reservoir, liquefaction and mudslides will occur after riprap. The required amount of riprap is large, the cost is high, and it is not conducive to promotion and application; the method of preloading drainage consolidation followed by covering is mainly to discharge the seepage water from the weak layer of the beach surface, and then cover the surface after the beach surface is consolidated. The preloading drainage consolidation method generally includes leveling the site, laying sand cushion layer, inserting plastic drainage board, layered preloading, etc. The construction process is relatively complicated, its quality is not easy to guarantee and the cost is relatively high. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a tailings pond closure and zoning disposal method to reduce the consumption of closure covering soil and complete the closure of the tailings pond quickly and safely.

[0006] The technical solution adopted by the present invention is:

[0007] A tailings pond closure and zoning disposal method, the specific steps are:

[0008] S1: Beach zoning: From the front of the dam to the end of the reservoir, the beach is divided into coarse sand area, soft beach area, and clear area-water area at the end of the reservoir;

[0009] S2: Treatment of coarse sand area: Dry it for 1-2 months to form a sedimentation beach with bearing capacity to support the entry of equipment and personnel; lay steel grids in the local low bearing capacity area to improve the overall performance;

[0010] S3: Soft beach area treatment: Use mechanical equipment to move the steel grille and bamboo raft to the junction of the coarse sand area and the soft beach area, and spread the steel grille in a straight line parallel to the dam surface. Leave a 1-2m overlap at the ends of the steel grille and tie them with wire; then lay the next row of steel grilles toward the end of the reservoir, leave a 1-2m overlap between the two rows of steel grilles, and tie them with wire. Repeat this process until the soft beach area is fully covered to form a unified whole;

[0011] After the steel grid is laid, the top layer of bamboo rafts is laid staggered from the junction of the coarse sand area and the soft beach area. When laying the bamboo rafts, the length direction of the bamboo rafts is consistent with the direction from the front of the dam to the tail of the reservoir;

[0012] S4: Disposal of the tail clarification area-water area: dig several seepage pits in the tail clarification area-water area, use the original backwater facilities of the tailings pond to return the upper clarified water to the concentrator through the backwater pump, and after the upper clarified water is drained, the area will be disposed of according to the soft beach area disposal method of S3;

[0013] S5: Beach reclamation and greening: After the bamboo rafts are laid in the entire reservoir area, a 5m-8m wide road is covered in the center of the dam body by forward piling soil from the front of the dam to the tail of the reservoir, which serves as the main road into the reservoir. Then, several branch roads are laid on both sides of the main road at a certain distance, eventually forming a grid area that intersects horizontally and vertically. Then, the topsoil is evenly pushed and spread in the grid from all sides, and finally the entire area is covered with soil. After the covering is completed, greening is carried out on the surface, and grass seeds or flower seeds are sown.

[0014] Specifically, the steel grating is in a rolled state, with a single roll width of 6-8m and a length of 20-30m; the bamboo raft is 30-50cm wide, 4-6m long, and 3-5cm thick.

[0015] Specifically, the covering soil in S5 is made of mountain soil, and the paving thickness is 25cm-40cm.

[0016] Due to the adoption of the above-mentioned technical solution, the present invention has the following advantages:

[0017] The disposal method of the present invention can quickly and safely complete the reinforcement disposal of the soft beach of the tailings pond, complete the closure of the pond surface within the specified time, and provide a working platform with high bearing capacity, low compressibility and low water content for the subsequent greening of the closure of the pond; and for the tailings pond that still uses the original tail drainage well of the pond to discharge flood water after closure, it not only effectively guarantees the progress, quality and process safety of the closure and covering of the soft beach, but also ensures that the overall slope of the beach after closure is consistent with the design, which is beneficial to the flood control and flood discharge safety after closure, and greatly reduces the consumption of closure covering soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of beach zoning and disposal methods of the present invention.

[0019] Figure 2 It is a cross-sectional schematic diagram after treatment of the present invention.

[0020] In the figure: 1-dam body, 2-coarse sand area, 3-soft beach area, 4-reservoir tail clarification area-water area, 5-return pump, 6-steel grille, 7-bamboo raft, 8-covering soil layer, 9-green plants. DETAILED DESCRIPTION

[0021] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments, which should not be used to limit the protection scope of the present invention. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention.

[0022] Combined with Figure 1-2 A tailings pond closure and partition disposal method shown in the figure has the following specific steps:

[0023] S1: Beach zoning: From the front of the dam body 1 to the end of the reservoir, the beach is divided into coarse sand area 2, soft beach area 3, and clear area at the end of the reservoir - water area 4.

[0024] S2: Disposal of coarse sand area 2: Due to the influence of natural sedimentation laws during the ore discharge process in coarse sand area 2, most of the coarse-grained tailings will remain within 0-30m in front of the dam. The coarse-grained tailings have good mechanical strength and can be dried for 1-2 months to form a sedimentary beach with high bearing capacity that can support the entry of equipment and personnel. Steel gratings 6 are laid in areas with local low bearing capacity to improve the overall performance.

[0025] S3: Disposal of soft beach area 3: The soft beach area 3 is mainly composed of fine-grained tailings, and even includes tailing silty clay and tailing clay with high clay content; the steel grille 6 and bamboo raft 7 are transported to the junction of the coarse sand area 2 and the soft beach area 3 by mechanical equipment. The steel grille 6 is in a rolled state, with a single roll width of 6-8m and a length of 20-30m; the steel grille 6 is spread out in a straight line parallel to the dam surface, and the ends of the steel grille 6 are overlapped by 1-2m and tied with iron wire; then the next row of steel grilles 6 is laid in the direction of the reservoir tail, and the overlap between the two rows of steel grilles 6 is retained by 1-2m, and tied with iron wire, and this is repeated until the soft beach area 3 is fully paved to form a unified whole; the steel grille 6 has high rigidity, good integrity, and is easy to lay, which improves the overall performance of the tailings in the soft beach area 3, and can evenly disperse and transmit the force when the beach surface is subjected to upper loads, avoiding local stress and sinking;

[0026] After the steel grille 6 is laid, the top layer of bamboo rafts 7 are staggered from the junction of the coarse sand area 2 and the soft beach area 3. The width of the bamboo raft 7 is 30-50cm, the length is 4-6m, and the thickness is 3-5cm. When the bamboo raft 7 is laid, the length direction of the bamboo raft 7 is consistent with the direction from the front of the dam to the tail of the reservoir; the bamboo raft 7 is light in weight and has a large contact area with the beach surface, which reduces the pressure of the upper load on the beach surface, thereby increasing the contact area and reducing the bearing capacity requirements of mechanical equipment or personnel.

[0027] S4: Treatment of the tail clarification area - water area 4: dig several seepage pits in the tail clarification area - water area 4, use the original return water facilities of the tailings pond to return the upper clarified water to the concentrator through the return water pump 5. After the upper clarified water is drained, the area is treated according to the soft beach area 3 treatment method of S3.

[0028] S5: Beach reclamation and greening: After the bamboo rafts 7 of the whole reservoir area are laid, a 5m-8m wide road is covered in the center of the dam body 1 by forward soil piling from the front of the dam to the tail of the reservoir as the main road into the reservoir. The covering soil is made of mountain soil with a paving thickness of 25cm-40 cm. Then, several branch roads are laid on both sides of the main road at a certain distance, and finally a grid area intersecting horizontally and vertically is formed. Then, the covering soil is evenly pushed and spread in the grid from all sides, and finally the covering of the entire area is completed; after the covering soil is completed, greening is carried out on the surface by sowing grass seeds and / or flower seeds; local grasses and flowers that are easy to survive, have shallow but well-developed horizontal root systems, and are short plants are used. Grasses such as tall fescue, dogtooth grass, and dragon beard grass can be used. Flowering plants that can sow themselves or grow all year round, such as flower allium and sunflower, are used; grass seeds or flower seeds are artificially sown, Water the grass promptly after sowing to ensure the survival rate. If the local survival rate is low, re-soak the grass seeds in time. After covering the soil and planting grass, it will take some time for the grass and soil to form a harmonious ecosystem. Check the survival rate of the grass later and re-soak it in time to ensure the recovery of the ecological environment of the entire reservoir area.

[0029] Parts of the present invention not described in detail are prior art.

[0030] The embodiments selected herein for the purpose of disclosing the invention are currently considered to be suitable, but it should be understood that the invention is intended to include all changes and modifications of the embodiments that fall within the scope of the concept and invention.

Claims

1. A tailings pond closure and zoning disposal method, characterized in that: The specific steps are: S1: Beach zoning: From the front of the dam to the end of the reservoir, the beach is divided into coarse sand area, soft beach area, and clear area-water area at the end of the reservoir; S2: Treatment of coarse sand area: Dry it for 1-2 months to form a sedimentation beach with bearing capacity to support the entry of equipment and personnel; lay steel grids in the local low bearing capacity area to improve the overall performance; S3: Soft beach area treatment: Use mechanical equipment to move the steel grille and bamboo raft to the junction of the coarse sand area and the soft beach area, and spread the steel grille in a straight line parallel to the dam surface. Leave a 1-2m overlap at the ends of the steel grille and tie them with wire; then lay the next row of steel grilles toward the end of the reservoir, leave a 1-2m overlap between the two rows of steel grilles, and tie them with wire. Repeat this process until the soft beach area is fully covered to form a unified whole; After the steel grid is laid, the top layer of bamboo rafts is laid staggered from the junction of the coarse sand area and the soft beach area. When laying the bamboo rafts, the length direction of the bamboo rafts is consistent with the direction from the front of the dam to the tail of the reservoir; S4: Disposal of the tail clarification area-water area: dig several seepage pits in the tail clarification area-water area, use the original backwater facilities of the tailings pond to return the upper clarified water to the concentrator through the backwater pump, and after the upper clarified water is drained, the area will be disposed of according to the soft beach area disposal method of S3; S5: Beach reclamation and greening: After the bamboo rafts are laid in the entire reservoir area, a 5m-8m wide road is covered in the center of the dam body by forward piling soil from the front of the dam to the tail of the reservoir, which serves as the main road into the reservoir. Then, several branch roads are laid on both sides of the main road at a certain distance, eventually forming a grid area that intersects horizontally and vertically. Then, the topsoil is evenly pushed and spread in the grid from all sides, and finally the entire area is covered with soil. After the covering is completed, greening is carried out on the surface, and grass seeds or flower seeds are sown.

2. The tailings pond closure and zoning disposal method according to claim 1 is characterized in that: The steel grille is in a rolled state, with a single roll width of 6-8m and a length of 20-30m; the bamboo raft is 30-50cm wide, 4-6m long and 3-5cm thick.

3. The tailings pond closure and zoning disposal method according to claim 1, characterized in that: The covering soil in the S5 is made of mountain soil, and the paving thickness is 25cm-40cm.

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