Strip mining and space comprehensive utilization method for end slope coal compression of open pit

Abstract

The application discloses a strip mining and space comprehensive utilization method for open-pit mine end-slope coal pressure, which comprises three steps of water interception and frozen soil column arrangement, door-shaped alternate mining and filling and underground space utilization; the water interception and frozen soil column arrangement plays the role of water source supply resistance to the far end aquifer, maintains the dryness of the mining working face, on the other hand, the freezing strengthens the mechanical properties of the soft rock, the crack development rock and the fissure containing water rock in the open-pit mine end-slope, provides resistance for the end-slope and improves the stability of the end-slope; the door-shaped frame provides a local stable environment for the end-slope coal pressure mining; the alternate mining mode avoids the concentrated long-time disturbance to a position of the end-slope; the underground mining chamber formed by the even section is used for water storage, the underground space is fully utilized without affecting the safety of mine production, and the dump site can provide heat preservation for the water storage hole in the end-slope, avoids the freezing of water resources and effectively solves the water use problem of the northern open-pit mine in winter.

Description

Technical Field

[0001] The present invention relates to a strip mining method for end-wall compressed coal, in particular to a strip mining method for end-wall compressed coal and a space comprehensive utilization method for an open-pit mine. Background Art

[0002] Mining the end-wall pressure coal in open-pit mines is a key way to increase open-pit mining rates and enhance the economic benefits of mining companies. This is especially true for open-pit mines with thick coal seams, where mining is in urgent demand and offers considerable profits. Currently, tunnel-type mining of end-wall pressure coal in open-pit mines has become a key method for recovering this pressure coal. The main process involves excavating horizontal or inclined tunnels at the end walls to recover the pressure coal. Due to its mature mining technology, comprehensive supporting equipment, and high mining efficiency, this method is gaining popularity among open-pit mines and is being used more widely. However, geological conditions vary significantly across different regions of my country. In some areas, the coal seam roof rock is well-developed with cracks and poor mechanical properties. In other areas, the coal seam roof contains large amounts of groundwater, resulting in soft rock and limited bearing capacity. Traditional mining methods are highly susceptible to roof collapse. Therefore, a method for mining the end-wall pressure coal in open-pit mines with water-bearing soft rock roofs is urgently needed. Summary of the Invention

[0003] In response to the problems existing in the above-mentioned prior art, the present invention provides a method for strip mining and comprehensive space utilization of the end-wall compressed coal in open-pit mines, which is suitable for the mining of the end-wall compressed coal in open-pit mines with water-containing soft rock roofs. The roof has good stability during mining and is not affected by groundwater.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solutions: a method for strip mining and space comprehensive utilization of open-pit mine end-wall compressed coal, comprising three steps: arranging water-blocking frozen soil columns, gate-type alternating mining and filling, and underground space utilization;

[0005] Arrangement of water-blocking frozen soil columns:

[0006] At a distance of 30-50m outside the recovery boundary of the open-pit end-wall coal, drill holes perpendicular to the surface at intervals downward along the spoil dump toward the stope. The drilling depth is 3-5m beyond the lower boundary of the end-wall coal, and the interval between adjacent boreholes is not less than 2m. Frozen soil pipes are installed inside the boreholes and connected to external freezing devices. The freezing devices transmit cold air to the frozen soil pipes, thereby freezing the rocks and water around the corresponding boreholes, forming water-blocking frozen soil columns.

[0007] Gate-type alternating mining and filling:

[0008] Divide the end-wall coal to be mined into several sections in sequence along the direction from the spoil dump to the stope, leaving an intermediate coal with a width of C between two adjacent sections. The width A of the odd-numbered sections and the width B of the even-numbered sections should satisfy A=B+2C;

[0009] A top frozen soil layer is constructed at the top coal-rock interface of the first section. Frozen support columns are constructed within the range C outside the left and right boundaries of the first section. The left and right ends of the top frozen soil layer extend to the outside of the frozen support columns. The top frozen soil layer and the frozen support columns on both sides form a portal frame. After the portal frame is constructed, a mining tunnel is arranged within the "gate" and the coal is mined until the end wall boundary. At this time, the width of the mining tunnel is the full width A of the first section.

[0010] During the mining process of the first section, the portal frame and the mining tunnel are constructed in the third section in the same manner and then mined. At this time, the width of the mining tunnel is the full width A of the third section.

[0011] After the first section of the mining tunnel is mined to the boundary, the first section of the mining tunnel is filled with paste, and at the same time, a portal frame and mining tunnel are constructed in the fifth section and the mining tunnel is mined. According to the same method, the third section of the mining tunnel is also filled with paste after it is mined to the boundary. When the filling bodies of the first and third sections reach strength, the freezing work of the freezing support columns on both sides of the first and third sections is completed, and then the top frozen soil layer is constructed at the top coal-rock interface of the second section. At this time, the top frozen soil layer and the filling bodies on both sides of the second section form a portal frame. After the portal frame of the second section is constructed, the mining tunnel is arranged in the "gate" and the coal therein is mined until the end wall boundary. At this time, the width of the mining tunnel is the full width B of the second section and the full width C of the middle coal on both sides thereof, that is, B+2C; after the mining of the even-numbered sections is completed, the water-blocking frozen soil column behind the mining tunnel stops supplying cooling, and the frozen soil pipe is taken out for recycling;

[0012] And so on, according to the above method, the odd-numbered sections and even-numbered sections are continuously mined;

[0013] Utilization of underground space:

[0014] After the mining of the even-numbered sections is completed, the internal surface of the mining tunnel is reinforced and support devices are installed. The bottom and two sides of the mining tunnel are waterproofed and the mining tunnel mouth is sealed, thereby forming an internal water storage cave at the end wall, and then the spoil dump follows up and covers it.

[0015] Furthermore, the method for constructing the top permafrost layer and frozen support columns is to first drill a hole, extract the coal resources, install a freezing pipe in the hole and freeze it, and then form the top permafrost layer and frozen support columns after freezing.

[0016] Furthermore, two rows of holes are symmetrically arranged at intervals on the side of the freezing pipe.

[0017] Furthermore, after the freezing work of the freezing support column is completed, additional grouting is injected into the freezing pipe.

[0018] Further, when the top frozen soil layer of the even section starts to be built, the top frozen soil layer of the odd section extending to the even section is first unfrozen by 1 / 3 of the width, and then the top frozen soil layer is built at the position of the top coal-rock interface of the even section.

[0019] Further, a water well is formed by drilling from the surface of the dump above the internal water storage cave into the internal water storage cave, and a water pumping device is arranged.

[0020] Compared with the prior art, the water-blocking frozen soil column in the present application has the following advantages: on the one hand, the water-blocking frozen soil column blocks the water supply from the far-end aquifer, and keeps the mining working face dry; on the other hand, the freezing strengthens the rock mechanics properties of the soft rock, the crack development rock and the fissure aquifer rock at the end slope of the open-pit mine, and provides resistance to the end slope and improves the stability of the end slope, thereby providing a reliable construction environment for the implementation of the present application; the door-shaped frame provides a local stable environment for the end-slope coal mining; the alternate mining method avoids the long-time disturbance to a certain position of the end slope; the underground mining cave formed by the even section is used for water storage, and the underground space is fully utilized without affecting the safety of the mine production; the overlying dump can provide heat preservation for the internal water storage cave of the end slope, avoid the freezing of the water resource, effectively solve the water problem in winter of the open-pit mine in the north, and improve the mine benefit. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 The present application is a schematic diagram of the section division and construction stage;

[0022] Fig. 2 The present application is a schematic diagram of the water-blocking frozen soil column arrangement;

[0023] Fig. 3 The present application is a construction position plan view;

[0024] In the figure: 1, end-slope coal; 2, recovery boundary; 3, ground surface; 4, water-blocking frozen soil column; 5, dump; 6, mining field; 7, first section; 8, second section; 9, third section; 10, fourth section; 11, fifth section; 12, sixth section; 13, seventh section; 14, middle coal; 15, top coal-rock interface; 16, top frozen soil layer; 17, frozen support column; 18, door-shaped frame; 19, mining equipment; 20, support device; 21, internal water storage cave; 22, water well. DETAILED DESCRIPTION

[0025] The present application will be further described below in combination with the drawings.

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] like Figs. 1-3 As shown, the present invention provides a method for strip mining of coal at the end of an open-pit mine and comprehensive space utilization, which includes three steps: arranging water-blocking frozen soil columns, portal-type alternating mining and filling, and underground space utilization.

[0028] Arrangement of water-blocking frozen soil columns:

[0029] At a distance of 30-50m outside the recovery boundary 2 of the end-wall compressed coal 1 of the open-pit mine, drills are drilled downward at intervals of 3 perpendicular to the ground surface along the spoil dump 5 toward the mining area 6. The drilling depth is 3-5m beyond the lower boundary of the end-wall compressed coal 1. The row and line spacing of the drilling holes are adjusted according to the geological and hydrological conditions. The more complex the geological and hydrological conditions are, the smaller the row and line spacing is. The interval between adjacent boreholes is not less than 2m. A frozen soil pipe is installed inside the borehole. The frozen soil pipe is a cylindrical pipe with an open end and a closed side. The frozen soil pipe is connected to an external freezing device. The freezing device transmits cold air to the frozen soil pipe, thereby freezing the rocks and water bodies around the corresponding borehole to form a water-blocking frozen soil column 4.

[0030] The functions of the water-blocking frozen soil column 4 are mainly divided into two aspects: on the one hand, it uses frozen water to block the water supply of the distant aquifer and keep the mining working face dry; on the other hand, it plays the role of an anti-slip pile. Since the overall stability of the end wall is reduced due to well mining, the water-blocking frozen soil column 4 can provide resistance for the end wall to prevent the end wall from sliding.

[0031] Gate-type alternating mining and filling:

[0032] like Fig. 1 As shown, the end-wall pressure coal 1 to be mined is divided into several sections in sequence along the spoil dump 5 toward the mining area 6. In this example, the end-wall pressure coal 1 to be mined is divided into section No. 1 7, section No. 2 8, section No. 3 9, section No. 4 10, section No. 5 11, section No. 6 12 and section No. 7 13. An intermediate coal 14 with a width of C is left between two adjacent sections. The width A of the odd-numbered sections and the width B of the even-numbered sections should satisfy A=B+2C. According to actual conditions, the width A of the odd-numbered sections is generally about 25m, the width B of the even-numbered sections is generally about 15m, and the width C of the intermediate coal 14 between two adjacent sections is generally about 5m. In this way, it can be ensured that the actual mining widths of the odd and even sections are equal in combination with subsequent process steps, which facilitates the consistency of selection of mining and support equipment.

[0033] The top frozen soil layer 16 is constructed within a range of 2.5 m above and below the top coal-rock interface 15 of the first section 7, i.e. a position range of a total height of 5 m. The frozen support column 17 is constructed within a range of 5 m outside the left and right boundary of the first section 7. The top frozen soil layer 16 and the frozen support column 17 are constructed by first drilling a hole by using a spiral drill, then extracting a small amount of coal resources, installing a freezing pipe in the hole and freezing. After freezing, the top frozen soil layer 16 and the frozen support column 17 are formed. The side surface of the freezing pipe is symmetrically arranged with two rows of holes at a certain distance. The holes are arranged on the side surface for subsequent secondary grouting to realize one pipe with two purposes. In order to improve the support strength of the top frozen soil layer 16, the left and right ends of the top frozen soil layer 16 extend to the outside of the frozen support column 17, and the extension width is generally 8 m. The top frozen soil layer 16 and the two side frozen support columns 17 form a door-shaped frame 18. The door-shaped frame 18 can provide effective support for the coal mining in the "door-shaped" frame. After the door-shaped frame 18 is constructed, a mining gallery is arranged in the "door-shaped" frame, and the coal in the mining gallery is mined until the end boundary. The existing shaft mining equipment 19 and process can be used in the mining process. At this time, the width of the mining gallery is the full width of the first section 7, i.e. 25 m.

[0034] In the mining process of the mining gallery of the first section 7, the door-shaped frame 18 and the mining gallery are constructed in the third section 9 according to the same method, and the mining gallery is mined. At this time, the width of the mining gallery is the full width of the third section 9, i.e. 25 m. After the mining of the mining gallery of the first section 7 reaches the boundary, the mining equipment 19 is withdrawn, and then the mining gallery of the first section 7 is filled with paste. At the same time, the door-shaped frame 18 and the mining gallery are constructed in the fifth section 11, and the mining gallery is mined. According to the same method, after the mining of the mining gallery of the third section 9 reaches the boundary, the paste filling is also performed.

[0035] When the filling bodies of Section 1 7 and Section 3 9 reach the strength, the freezing work of the frozen support columns 17 on both sides of Section 1 7 and Section 3 9 is completed, and then the grouting is supplemented in the freezing pipes. The supplementary grouting is carried out using the opened freezing pipes to make up for the freezing pipe space and the collapsed volume caused by the melting of the frozen paste part to ensure that its strength is sufficient. After the supplementary grouting is completed, the top frozen soil layer 16 is constructed at the top coal-rock interface 15 of Section 2 8. When the construction of 16 begins, first thaw 1 / 3 of the width of the top frozen soil layer 16 of Section 1 7 and Section 3 9 extending to Section 2 8, and then construct the top frozen soil layer 16 within the range of 2.5m above and below the top coal-rock interface 15 of Section 2 8, that is, the total height of 5m, so that the top frozen soil layer 16 of Section 2 8 and the top frozen soil layers 16 of Section 1 7 and Section 3 9 on both sides thereof are frozen into a whole, thereby improving the supporting effect; at this time, the top frozen soil layer 16 and The filling bodies of Section 1 7 and Section 3 9 on both sides of Section 2 8 form a portal frame 18. After the construction of the portal frame 18 of Section 2 8 is completed, a mining tunnel is arranged in the "gate shape" and the coal therein is mined until the end wall boundary. At this time, the width of the mining tunnel is the sum of the full width of Section 2 8 and the full width of the middle coal 14 on both sides thereof, that is, 15+2*5=25m. In this way, the final mining width of the even-numbered and odd-numbered sections is kept the same, without the need to purchase or adjust additional coal mining equipment, reducing mining costs and improving mining efficiency. Efficiency; After the mining of section No. 2 8 is completed, the cooling of the water-blocking frozen soil column 4 at the rear of the mining tunnel, that is, near the side of the spoil dump 5, is stopped, and the frozen soil pipe is taken out for recycling. Because the section has been mined and filled at this time, there is no fear of water seepage, and the cooling should be stopped in time to reduce energy consumption; and so on, according to the above method, the odd-numbered sections and even-numbered sections are continuously mined, that is, in the process of mining odd-numbered sections, whenever there is an even-numbered section that meets the condition of "the odd-numbered sections on both sides have been completed and filled", this even-numbered section is mined.

[0036] The two steps of arranging water-cutting frozen soil columns and portal-type alternating filling mining have a sequential relationship in implementation. The former provides the necessary safe hydrological and geological guarantees for the implementation of the latter. Therefore, the two processes are not simply spliced ​​together, but support each other.

[0037] Utilization of underground space:

[0038] After the mining of the even-numbered sections is completed, the interior of the mining tunnel is no longer filled. Instead, the interior surface of the mining tunnel is reinforced and a support device 20 is installed. The bottom and two sides of the mining tunnel are waterproofed and the mining tunnel mouth is sealed, thereby forming an internal water storage cave 21 in the end wall. Then, the spoil dump 5 quickly follows up and covers it. After the internal water-blocking frozen soil column 4 and the gate-shaped frozen soil are thawed, the water inside the end wall flows and gathers into the internal water storage cave 21 in the end wall. At the same time, the groundwater at the far end will also gather into the internal water storage cave 21 in the end wall, thereby storing a large amount of water resources underground. A water well 22 is formed by drilling a hole from the surface of the spoil dump 5 above the internal water storage cave 21 into the internal water storage cave 21. A pumping device is deployed to utilize the water resources stored in the underground space. The overlying spoil dump 5 can provide insulation for the internal water storage cave 21, preventing water resources from freezing, effectively solving the winter water problem in northern open-pit mines.

[0039] Since the construction stages of each section are different at the same time, in order to show the status of each section at different stages more clearly and completely, Fig. 1 Section 1 7, Section 3 9 and Section 5 11 are in the stage of having been mined and filled, Section 2 8 is in the stage of having its internal water storage cave 21 and water intake well 22 built, Section 4 10 and Section 7 13 are in the stage of being mined, and Section 6 12 is in the stage of waiting to be mined.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent replacements, and improvements made to the above embodiments based on the technical essence of the present invention shall be included in the scope of protection of the technical solution of the present invention.

Claims

1. A method for strip mining and comprehensive space utilization of open-pit mine end-wall coal, characterized in that: It includes three steps: arranging water-blocking frozen soil columns, alternating mining and filling in a gate-type manner, and utilizing underground space; Arrangement of water-blocking frozen soil columns: At a distance of 30-50 m from the outer side of the recovery boundary (2) of the open-pit mine side pressure coal (1), drill holes vertically (3) downward along the spoil dump (5) in the direction of the stope (6), with the drilling depth exceeding 3-5 m from the lower boundary of the side pressure coal (1), and the interval between adjacent boreholes being not less than 2 m. A frozen soil pipe is installed inside the borehole, and the frozen soil pipe is connected to an external freezing device. The freezing device transmits cold energy to the frozen soil pipe, thereby freezing the rocks and water bodies around the corresponding borehole, forming a water-blocking frozen soil column (4); Gate-type alternating mining and filling: The end pressure coal (1) to be mined is sequentially divided into a number of sections along the direction from the spoil dump (5) to the stope (6), with an intermediate coal (14) of width C left between two adjacent sections. The width A of the odd-numbered sections and the width B of the even-numbered sections should satisfy A=B+2C. A top frozen soil layer (16) is constructed at the position of the top coal-rock interface (15) of the first section, and frozen support columns (17) are constructed within the range C outside the left and right boundaries of the first section. The left and right ends of the top frozen soil layer (16) extend to the outside of the frozen support columns (17). The top frozen soil layer (16) and the frozen support columns (17) on both sides form a door-shaped frame (18). After the door-shaped frame (18) is constructed, a mining tunnel is arranged in the "door shape" and the coal therein is mined until the end wall boundary. At this time, the width of the mining tunnel is the full width A of the first section. During the mining process of the mining tunnel in the first section, the same method is used to construct the door-shaped frame (18) and the mining tunnel in the third section and mine the mining tunnel. At this time, the width of the mining tunnel is the full width A of the third section. After the first section of the mining tunnel is mined to the boundary, the first section of the mining tunnel is filled with paste, and at the same time, the door frame (18) and the mining tunnel are constructed in the fifth section and the mining tunnel is mined. According to the same method, the third section of the mining tunnel is also filled with paste after the mining reaches the boundary. When the filling body of the first section and the third section reaches the strength, the freezing work of the freezing support columns (17) on both sides of the first section and the third section is completed, and then the top frozen soil layer ( 16), at this time, the top frozen soil layer (16) and the filling bodies on both sides of the second section form a door-shaped frame (18). After the door-shaped frame (18) of the second section is constructed, a mining tunnel is arranged in the "door-shaped" and the coal therein is mined until the end wall boundary. At this time, the width of the mining tunnel is the full width B of the second section and the full width C of the middle coal (14) on both sides thereof, that is, B+2C. After the mining of the even-numbered sections is completed, the water-blocking frozen soil column (4) behind the mining tunnel stops supplying cooling, and the frozen soil pipe is taken out for recycling; And so on, according to the above method, the odd-numbered sections and even-numbered sections are continuously mined; Utilization of underground space: After the mining of the even-numbered sections is completed, the internal surface of the mining tunnel is reinforced and a support device (20) is installed. The bottom surface and two side surfaces of the mining tunnel are waterproofed and the mining tunnel mouth is sealed, thereby forming an internal water storage cave (21) at the end wall, and then the spoil dump (5) follows up and covers it.

2. The method for strip mining and space comprehensive utilization of open-pit mine end-wall coal according to claim 1, characterized in that: The method for constructing the top frozen soil layer (16) and the frozen support column (17) is to first drill a hole, extract the coal resources, install a freezing pipe in the hole and freeze it, and then form the top frozen soil layer (16) and the frozen support column (17).

3. The method for strip mining and comprehensive space utilization of open-pit mine end-wall coal according to claim 2, characterized in that: Two rows of holes are symmetrically arranged at intervals on the side of the freezing pipe.

4. The method for strip mining and comprehensive space utilization of open-pit mine end-wall coal according to claim 3, characterized in that: After the freezing work of the freezing support column (17) is completed, additional grouting is injected into the freezing pipe.

5. The method for strip mining and comprehensive space utilization of open-pit mine end-wall coal according to claim 3, characterized in that: When the top frozen soil layer (16) of the even-numbered section begins to be constructed, the top frozen soil layer (16) of the odd-numbered section extending to the even-numbered section is first thawed by 1 / 3 of its width, and then the top frozen soil layer (16) is constructed at the position of the top coal-rock interface (15) of the even-numbered section.

6. The method for strip mining and space comprehensive utilization of open-pit mine end-wall coal according to claim 1, characterized in that: A hole is drilled from the surface of the spoil field (5) above the internal water storage hole (21) into the internal water storage hole (21) to form a water well (22) and a water pumping device is arranged.

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