Fine mining and ecological construction method for near-surface layer of strip mine in desert region

Abstract

The invention discloses a fine mining and ecological construction method for a near-surface layer of a strip mine in a desert region. The fine mining and ecological construction method comprises the three steps of fine mining of the near-surface layer, reconstruction of an ecological surface layer and zoning and staged consolidation. By means of refined mining, layered mining of the near-surface soil layer and the gravel curtain layer is achieved, the soil quality is improved, and the planting effect is guaranteed; the gravel curtain layer is used for screening and targeted storage, so that a basic material is provided for subsequent recovery; layering and zoning repeated consolidation is achieved, natural force of water, wind and the like is fully utilized, the construction cost is reduced, the gravel curtain layer structure is restored to the maximum extent, and the mining area environment is protected; the method has no influence on strip mine production, the construction process is simple, operation is convenient, and the labor cost is not increased.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for fine mining of open-pit mines, in particular to a method for fine mining and ecological construction of near-surface layers of open-pit mines in desert areas. BACKGROUND

[0002] The gravel curtain layer is a product formed by long-term wind erosion of the surface of arid desert areas. The specific causes are complex, and there are generally two types. One is that the sand between gravels is blown away by the wind, causing the gravels to be exposed. The other is that the sand blown by the wind is trapped by the gravels and continuously deposited under the gravel joints in the temperature difference, eventually supporting the gravels. The gravel curtain layer plays an important role and is particularly important for soil water conservation, dust reduction, and other aspects, and is an important guarantee for the maintenance and restoration of desert ecosystems.

[0003] During open-pit mining, the near-surface soil layer is mixed with the gravel curtain layer, and overall stripping will cause the soil to have a high stone content and poor quality. When discarded to the dump, the planting effect is poor. At the same time, the gravel curtain layer that is stripped together cannot be distinguished and restored on the surface of the dump, significantly affecting the ecological restoration effect of the dump and the control of dust in the mining area. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides a method for fine mining and ecological construction of near-surface layers of open-pit mines in desert areas, which separates the near-surface soil layer and the gravel curtain layer for layered mining and repeated consolidation in different zones, thereby maximizing the restoration of the structure of the gravel curtain layer.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for fine mining and ecological construction of near-surface layers of open-pit mines in desert areas, comprising the following steps: Fine mining of near-surface layers: In the stripping area of the open-pit mine, the area from the surface to the soil-rock interface is divided into a gravel curtain layer, a surface soil layer, and a bottom soil layer in sequence; and the mining and transportation equipment is arranged on the surface of the bottom soil layer to separate the gravel curtain layer and the surface soil layer for layered mining; The bottom soil layer is excavated and mined, and then the stripping and mining of the lower bench are continued; The stripped gravel curtain layer and surface soil layer are loaded into a mobile screening machine arranged on the working face, and a first belt conveyor, a second belt conveyor, and a third belt conveyor are arranged below the mobile screening machine, and the three conveyors are arranged in a "pin" shape; Ecological surface layer reconstruction: The stripped material is discarded in the open-pit mine goaf to form a dump, and a new bottom soil layer, a near-surface water-resisting layer, a new surface soil layer, a gravel curtain bottom layer, and a gravel curtain surface layer are sequentially laid from bottom to top on the bottom of the uppermost bench of the dump; the gravel curtain bottom layer and the gravel curtain surface layer jointly form a new gravel curtain layer; Zonal and periodic consolidation: According to the annual advancing distance of the dump, the dump is equally divided into 12 parts, following the formation process of the dump, from the stope to the dump direction, the dump is sequentially divided into pressure consolidation area, water consolidation area, complex pressure consolidation area, complex water consolidation area and wind-sand area; the dump of the last year next to the wind-sand area is the sand supplement area.

[0006] Further, in the pressure consolidation area, continuous rolling or vibration compaction is carried out above the new gravel curtain.

[0007] Further, in the water consolidation area, flood irrigation is adopted above it to accelerate settlement and secondary consolidation.

[0008] Further, in the complex pressure consolidation area, continuous rolling or vibration compaction is carried out when it is not completely dried.

[0009] Further, in the complex water consolidation area, small water flood irrigation is adopted above it.

[0010] Further, in the sand supplement area, small water mixed with fine materials is used to supplement the surface layer of the sand supplement area.

[0011] Further, the mobile screening machine adopts a vibrating screen with a 1cm mesh, is arranged at an inclination of 50-60°, a first belt conveyor is connected to the screened gravel, and a second belt conveyor and a third belt conveyor are respectively connected to the surface fine material screened from the gravel curtain layer and the soil fine material screened from the surface soil layer.

[0012] Further, the soil fine material is stored by covering with a dense mesh and sprinkling water on the surface, the surface fine material is packaged with airtight devices, and the gravel is transported to the dump for bulk storage.

[0013] Further, the pressure consolidation area, water consolidation area, complex pressure consolidation area, complex water consolidation area, wind-sand area and sand supplement area are each divided into multiple planting areas and non-planting areas along the advancing direction, with a length of 1-2m; the thickness of the new gravel curtain layer at the upper part of the planting area is 1 / 2-1 / 3 of the thickness of the new gravel curtain layer at the upper part of the non-planting area.

[0014] Compared with the prior art, the present application realizes the layered mining of the near-surface soil layer and the gravel curtain layer, improves the soil quality and ensures the planting effect; the gravel curtain layer is screened and stored for subsequent recovery; the layered and zoned repeated consolidation fully utilizes the natural forces of water and wind, reduces the construction cost, maximizes the restoration of the gravel curtain layer structure, and protects the mining area environment; the present application does not affect the production of the open-pit mine, the construction process is simple and easy to operate, and does not increase the labor cost. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present application; Figure 2 This is a schematic diagram showing the relative positions of the mobile screening machine and the three-belt conveyor of the present invention; Figure 3 This is a schematic diagram of the uppermost stepped layered structure of the boundary spoil heap of the present invention; Figure 4 This is a schematic diagram of the partitioned consolidation of the present invention; In the diagram: 1-Stripping area; 2-Gravel curtain layer; 3-Topsoil layer; 4-Subsoil layer; 5-Mobile screening machine; 6-First belt conveyor; 7-Second belt conveyor; 8-Third belt conveyor; 9-Dumping area; 10-Upper step of the dumping area to the boundary; 11-New subsoil layer; 12-Near-surface aquitard; 13-New topsoil layer; 14-Gravel curtain bottom layer; 15-Gravel curtain surface layer; 16-Pressure consolidation zone; 17-Water consolidation zone; 18-Re-pressure consolidation zone; 19-Re-water consolidation zone; 20-Wind-blown sand zone; 21-Sand replenishment zone. Detailed Implementation

[0016] The invention will now be further described with reference to the accompanying drawings.

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] like Figure 1 As shown, the present invention provides a technical solution comprising three major steps: fine surface mining, ecological surface reconstruction, and phased consolidation in different zones.

[0019] Near-surface fine mining: In arid desert regions, vegetation productivity is low, and the humus content is not high in any soil sequence. Therefore, the division of near-surface soil layers is mainly based on particle size distribution, bulk density, and mineral composition. In the open-pit mine stripping area 1, from the surface downwards to the soil-rock interface, the soil is divided into a gravel curtain layer 2, a topsoil layer 3, and a subsoil layer 4. The gravel curtain layer 2 is 1-3 cm thick, the topsoil layer 3 is 20-40 cm thick, and the subsoil layer 4 is extracted to the soil-rock interface. When the soil-rock interface exceeds the bottom of the first stripping step, the soil layer corresponding to the first stripping step is defined as the subsoil layer 4.

[0020] The mining and transportation equipment, preferably a front-loading machine, stands on the surface of the topsoil layer 3 and the subsoil layer 4 respectively to mine the gravel curtain layer 2 and the topsoil layer 3; a hydraulic backhoe is used to excavate and mine the subsoil layer 4, and then it is transported by truck to the designated area of ​​the spoil heap 9 for use in ecological restoration or as stripping material for disposal. Then, the stripping and dumping operation of the lower bench continues to create site conditions for ecological restoration after resource extraction.

[0021] The stripped gravel blanket 2 and the surface soil layer 3 are respectively loaded into the mobile screening machine 5 arranged at the working face, as shown in Figure 2 The mobile screening machine 5 adopts a vibrating screen with a 1cm mesh, is arranged at an inclination of 50-60°, and is provided below with a first belt conveyor 6, a second belt conveyor 7 and a third belt conveyor 8, which are arranged in a "pin" shape; the first belt conveyor 6 is connected to the gravel screened from the gravel blanket 2 and the surface soil layer 3, and the second belt conveyor 7 and the third belt conveyor 8 are respectively connected to the surface fine material screened from the gravel blanket 2 and the soil fine material screened from the surface soil layer 3.

[0022] The soil fine material is stored by covering with a dense mesh screen and spraying water on the surface to promote the formation of a crust to reduce wind erosion; the surface fine material is packaged by airtight device, which can be in a bag, a barrel or a warehouse, or stored in a closed factory or covered with plastic cloth and the like; the gravel is transported to the designated area of the dump for storage.

[0023] Ecological surface layer reconstruction: As shown in Figure 1 and 3 , the stripped material in the goaf of the open-pit mine forms a dump 9, and a new subsoil layer 11, a near-surface water-resisting layer 12, a new surface soil layer 13, a gravel blanket bottom layer 14 and a gravel blanket surface layer 15 are sequentially laid from bottom to top at the bottom of the last step 10 of the dump; the gravel blanket bottom layer 14 and the gravel blanket surface layer 15 jointly form a new gravel blanket.

[0024] The near-surface water-resisting layer 12 has a thickness of 3-5m and is constructed by clay, mudstone and other easy cementing materials mined from the open-pit mine, which can avoid the infiltration of atmospheric precipitation or water from shallow aquifer to the deep part of the dump 9; when the distance between the near-surface water-resisting layer 12 and the ground surface needs to be adjusted, the thickness of the subsoil layer 4 is adjusted; the new surface soil layer 13 is laid by the soil fine material newly collected or stored, has a thickness of 20-30cm and is compacted by equipment to control the unit weight; since the stones with a particle size greater than 1cm are removed by screening during the collection process, the permeability is reduced, which is beneficial to the conservation of soil water and nutrients; the surface of the new surface soil layer 13 is sprayed with the surface fine material screened from the gravel blanket 2 with a thickness of 3-5cm to form the gravel blanket bottom layer 14, and water is sprayed at the same time to suppress dust; the surface fine material, clay and gravel are mixed in a volume ratio of 1:1:1 to form new gravel blanket raw materials, and the surface fine material and clay are mixed in a volume ratio of 1:1 to form new gravel blanket binding materials; the new gravel blanket raw materials with a thickness of 8cm are laid on the upper part of the gravel blanket bottom layer 14, and the new gravel blanket binding materials with a thickness of 2cm are laid above the new gravel blanket raw materials to jointly form the new gravel blanket surface layer 15.

[0025] Partitioned and phased consolidation: AsFigure 4 As shown, according to the annual advancing distance of the dump 9, the dump 9 is equally divided into 12 parts, following the formation process of the dump 9, from the mining field to the direction of the dump 9, the dump 9 is sequentially divided into the pressure consolidation area 16, the water consolidation area 17, the re-pressure consolidation area 18, the re-water consolidation area 19 and the wind-sand area 20; the dump 9 of the last year next to the wind-sand area 20 is the sand supplement area 21.

[0026] In the pressure consolidation area 16, the mine machinery is used for continuous rolling or vibration compaction above the new gravel curtain layer, due to the presence of clay, the materials in the gravel curtain surface layer 15 and the gravel curtain bottom layer 14 are mutually compacted, adhered and consolidated, and the hardness of the gravel curtain surface layer 15 is improved. In the water consolidation area 17, the surface is flooded with a large amount of water, relying on the water infiltration process to accelerate the settlement and secondary consolidation of the new gravel curtain raw materials and the new gravel curtain adhesive, and to accelerate the mutual consolidation of the gravel curtain surface layer 15 and the gravel curtain bottom layer 14. In the re-pressure consolidation area 18, when the soil is not completely dry, heavy mine machinery is used for continuous rolling or vibration compaction, which plays a role of secondary pressure consolidation. In the re-water consolidation area 19, the surface is flooded with a small amount of water, relying on the water infiltration process to continuously consolidate. In the wind-sand area 20, all kinds of vehicles and personnel are prohibited to enter, and the surface layer of the dump 9 will take away the unstable fine materials under the action of wind and sand, thereby fully simulating the gravel curtain layer structure, preventing soil erosion and blocking soil capillary action to reduce water evaporation. At the same time, when the area experiences rainfall, the fine materials will further sink and support the gravel. In the sand supplement area 21, a small amount of water mixed with fine materials is used to supplement the surface layer of the sand supplement area 21, the water can accelerate the consolidation, and the mixed fine materials can timely make up for the holes in the new gravel curtain layer after experiencing wind and sand, avoiding further damage by subsequent wind and sand.

[0027] The above-mentioned small water and large water correspond to the standards of small rain and heavy rain in meteorology; the "dry" in the above-mentioned completely dry adopts the standard of agricultural meteorology, generally adopts "<60% of FC", that is, the current water content of the soil is lower than 60% of the field water holding capacity of the soil, at this time the soil is considered to be dry soil.

[0028] In order to ensure the greening effect of each subarea in the later period, the pressure consolidation area 16, the water consolidation area 17, the re-pressure consolidation area 18, the re-water consolidation area 19, the wind-sand area 20 and the sand supplement area 21 are each divided into multiple planting areas and non-planting areas along the advancing direction, with a length of 1-2m. The thickness of the new gravel curtain layer at the upper part of the planting area is 1 / 2-1 / 3 of the thickness of the new gravel curtain layer at the upper part of the non-planting area, which can ensure the plant germination of the planting area and the dust suppression effect of the non-planting area.

[0029] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. The presently disclosed embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. No reference to an item in the claims is to be construed as an admission that such item is admitted prior art.

[0030] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any slight modification, equivalent replacement and improvement made to the above embodiments according to the technical essence of the present application shall be included in the protection scope of the technical scheme of the present application.

Claims

1. A method for fine near-surface mining and ecological construction in open-pit mines in desert areas, characterized in that, It includes the following steps: Fine exploitation of the near-surface layer: In the stripping area (1) of the open-pit mine, from the surface down to the soil-rock interface, it is successively divided into a gravel curtain layer (2), a topsoil layer (3), and a subsoil layer (4); the mining and transportation equipment stands on the surface of the subsoil layer (4) and mines and loads the gravel curtain layer (2) and the topsoil layer (3) in layers; Excavate and load the subsoil layer (4) downward, and then continue with the stripping, mining, and dumping operations of the lower bench; Load the stripped gravel curtain layer (2) and topsoil layer (3) into the mobile screening machine (5) arranged on the working face respectively. Under the mobile screening machine (5), a first belt conveyor (6), a second belt conveyor (7), and a third belt conveyor (8) are arranged, and the three conveyors are arranged in a "pin" shape; Ecological surface reconstruction: In the waste dump area of the open-pit mine, waste is discharged to form a waste dump (9). Starting from the bottom of the uppermost bench (10) of the waste dump that has reached the boundary, a new subsoil layer (11), a near-surface water-proof layer (12), a new topsoil layer (13), a gravel curtain bottom layer (14), and a gravel curtain surface layer (15) are successively laid from bottom to top; the gravel curtain bottom layer (14) and the gravel curtain surface layer (15) together form a new gravel curtain layer; Zoned and staged consolidation: According to the annual advancing distance of the waste dump (9), the waste dump (9) is equally divided into 12 parts. Following the formation process of the waste dump (9), from the stope to the direction of the waste dump (9), the waste dump (9) is successively divided into a pressure consolidation area (16), a water consolidation area (17), a re-pressure consolidation area (18), a re-water consolidation area (19), and a sand and wind area (20); the waste dump (9) of the previous year adjacent to the sand and wind area (20) is a sand filling area (21).

2. The method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, In the pressure consolidation area (16), continuous rolling or vibration compaction is carried out above the new gravel curtain layer.

3. The method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, In the water consolidation area (17), large water flooding is adopted above it to accelerate settlement and secondary consolidation.

4. The method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, In the re-pressure consolidation area (18), continuous rolling or vibration compaction is carried out when it is not completely dry.

5. The method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, In the re-water consolidation area (19), small water flooding is adopted above it.

6. The method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, In the sand filling area (21), small water mixed with fine materials is used to irrigate the surface of the sand filling area (21) for sand filling.

7. The method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, The mobile screening machine (5) uses a vibrating screen with a 1 cm mesh size and is arranged at an inclination of 50 - 60°. The first belt conveyor (6) receives the screened gravel, and the second belt conveyor (7) and the third belt conveyor (8) respectively receive the surface fine materials screened from the gravel curtain layer (2) and the soil fine materials screened from the topsoil layer (3).

8. A method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 7, characterized in that, The soil fine materials are stored by covering them with a close-mesh net and sprinkling water on the surface. The surface fine materials are encapsulated with a closed device, and the gravel is transported to the waste dump for bulk storage.

9. A method for near-surface fine mining and ecological construction in open-pit mines in desert areas according to claim 1, characterized in that, For the pressure consolidation area (16), the water consolidation area (17), the re-pressure consolidation area (18), the re-water consolidation area (19), the sand and wind area (20), and the sand filling area (21), along the advancing direction, each partition is divided into multiple planting areas and non-planting areas with a limit of 1 - 2 m in length at intervals; the thickness of the new gravel curtain layer in the upper part of the planting area is 1 / 2 - 1 / 3 of the thickness of the new gravel curtain layer in the upper part of the non-planting area.

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