A method for digging down steps in a large open-pit mining pit

Abstract

The invention discloses a method for digging down steps in a large open-pit mine, comprising the following steps: constructing a shallow hole blasthole group on the upper plate step of an ore body in an aquifer, forming a temporary step after blasting; dividing the temporary step into a temporary water storage area and a platform area; arranging a deep hole blasthole group in the temporary water storage area; arranging a differential blasthole group in the platform area, blasting the deep hole blasthole group to form an interception and drainage pool, using a mudstone water-proof layer as a water-proof retaining wall of the interception and drainage pool; blasting the differential blasthole group to form an interception ditch and a slope platform, the interception and drainage pool, the interception ditch and the slope platform are connected to form a pit bottom advance interception system, so that the underground flows to the interception and drainage pool; pumping out the groundwater in the interception and drainage pool, lowering the groundwater level, and digging down the ore body to the pit bottom platform. The method of the invention can completely eliminate the flooding problem of digging down in a large open-pit mine, and the implementation difficulty is not great and the cost is low.

Description

Technical Field

[0001] The invention belongs to the mining industry, and in particular relates to a step-down digging method for a large water open pit. Background Art

[0002] When mining a large water deposit in the open pit, groundwater problems such as slope seepage, water gushing from blastholes and water filling in the mining area affect the stability of the sidewalls, deteriorate the mining environment, increase blasting costs, and lead to poor blasting effects, which seriously affect the safe mining of mines. Especially when digging in the open pit, the working space is small, and groundwater often causes the digging space under the steps to be flooded, making it impossible to carry out mining operations. For this reason, people have adopted some methods to control it. The existing control methods mainly include the following methods:

[0003] (1) Pre-drainage of deep holes on the surface can lower the groundwater level in advance. This method involves penetrating the main aquifer during surface construction to expose a large-diameter hole group in a highly permeable fissure or karst zone, and using a deep well pump to pump water to form a deep and large precipitation funnel in advance or directly intercept groundwater flow to keep the protected area in a drainage state. This method has high engineering and drainage costs, and the surface drainage holes are far from the bottom of the pit, so they are not very targeted and it is difficult to effectively guarantee the drainage effect of the excavation area under the steps.

[0004] (2) Horizontal drainage hole management technology: This technology involves drilling horizontal or near-horizontal holes into the aquifer on the developed steps to expose the aquifer and lower the water level of the aquifer. This method cannot lower the groundwater level in advance, so it is difficult to solve the groundwater management problem when digging under the steps.

[0005] (3) Seepage interception ditch drainage technology is to construct drainage ditches on the developed steps, use the drainage ditches to expose the aquifer and lower the water level of the aquifer. This technology is limited by the excavation depth, and the groundwater level is generally reduced to a low level. The interception ditch management technology reduces the groundwater level. For example, the Chinese patent application CN111852553A discloses a method for rapid depression trenching in an open-pit mine with a large water inflow. According to the hydrogeological conditions of the mine site, the mining area is divided into an area with a large water inflow and an area with a small water inflow. An advance drainage pool is arranged in the area with a large water inflow, and a three-layered advance drainage pool is formed by excavation. In the area with a small water inflow, an inlet and outlet ditch is arranged, and a three-stage inlet and outlet ditch and subsequent opening ditch, expansion wall and excavator inlet and outlet steps are formed. This method actually adopts a step-type water collection pit scheme at the bottom of the pit, which can promote trenching work when the water inflow at the bottom of the pit is small, but it cannot solve the overall water prevention and control problem of excavation under the steps.

[0006] Therefore, the problem of groundwater management during excavation under steps has not been effectively solved at a reasonable cost. Summary of the invention

[0007] In order to solve the problem of groundwater treatment when digging under steps at a relatively low cost and enable the mining under the steps to proceed smoothly, the present invention provides a method for digging under steps in a large water open pit.

[0008] The step-down digging method of the large water open pit of the present invention comprises the following steps:

[0009] (1) The indirect roof of the open pit is an aquifer, the roof is a mudstone aquiclude, and the ore body is a weak aquifer;

[0010] (2) Constructing a group of shallow blastholes on the upper wall step of the ore body in the aquifer, and forming a temporary step after blasting the shallow blasthole group;

[0011] (3) Dividing the temporary steps described in step (2) into a temporary water tank area and a platform area;

[0012] (4) Arranging a deep hole blasthole group in the temporary water storage area in step (3); arranging a differential blasthole group in the platform area, wherein the blasthole depth of the differential blasthole group is arranged in a direction from close to the mudstone aquiclude to far away from the mudstone aquiclude according to the rule of gradually deepening from shallow to deep;

[0013] (5) The deep hole blast hole group in blasting step (4) forms an interception and drainage pool, and the mudstone impermeable layer in step (1) serves as a water-blocking retaining wall of the interception and drainage pool; the differential blast hole group in blasting step (4) forms an interception ditch and a slope platform, and the interception and drainage pool, the interception ditch and the slope platform are connected to form a pit bottom advance water interception system, so that underground water flows to the interception and drainage pool;

[0014] (6) Drain the groundwater in the interception and drainage pool, lower the groundwater level, and dig down to the ore body until it reaches the platform at the bottom of the pit.

[0015] Furthermore, the pit bottom platform can be arranged in multiple levels. When the ore body is mined to the first pit bottom platform, the water-proof retaining wall above the first pit bottom platform is broken, and then the steps (1) to (6) are repeated to excavate the ore body until the second pit bottom platform. In this way, the excavated ore body can reach any preset pit bottom platform.

[0016] The hole depth of the shallow blasthole group is controlled above the groundwater level. Preferably, the hole depth of the shallow blasthole group is controlled 50 cm above the groundwater level. The hole diameter of the shallow blasthole group is φ110mm~φ150mm, the hole spacing is 6~8m, and the row spacing is 5~6m.

[0017] Furthermore, the length of the temporary water storage area is 25 to 35 m, and the width is 10 to 15 m.

[0018] The diameter of the deep hole blasthole group is φ110mm~φ150mm, the hole spacing is 6~8m, the row spacing is 5~6m, and the hole depth is controlled at 15~20m.

[0019] The hole depths of the differential blasthole groups are set from shallow to deep in the range of 10 to 15 meters.

[0020] The present invention adopts a combination of deep and shallow hole blasting on the upper plate of the ore body and forms an advanced interception and drainage system at the bottom of the step, which can efficiently and accurately drain the groundwater level in the planned excavation area in advance, avoid a large influx of groundwater, improve the working conditions in the excavation area, reduce operating costs, and improve operating efficiency; the implementation of the present invention can completely eliminate the problem of water disasters in excavation of large open-pit mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a plan diagram of the shallow hole excavation plan.

[0022] Figure 2 yes Figure 1 Section view along line AA.

[0023] Figure 3 It is a plan diagram of a combined deep and shallow hole excavation scheme.

[0024] Figure 4 yes Figure 3 Section view along line BB.

[0025] Figure 5 yes Figure 3 Cross-sectional view along line CC.

[0026] Figure 6 It is a plan view of the advance water interception system.

[0027] Figure 7 yes Figure 6 Cross-sectional view along line DD.

[0028] Figure 8 yes Figure 6 Cross-sectional view along line EE.

[0029] Fig. 9 It is a plan diagram of the plan for step excavation of the ore body.

[0030] Fig.10 yes Fig. 9 Cross-sectional view along line FF.

[0031] Fig.11 yes Fig. 9 Sectional view along line GG.

[0032] Figure numerals: indirect roof 1, roof 2, ore body 3, groundwater level 4, on the ore body, upper wall step 5, shallow hole blasthole group 6, temporary step 7, deep hole blasthole group 8, temporary water storage area 9, platform area 10, differential blasthole group 11, intercepting and drainage pool 12, intercepting ditch 13, slope platform 14, pit bottom platform 15, drainage system 16. DETAILED DESCRIPTION

[0033] Some embodiments of the present invention, but not all embodiments, are described below in conjunction with the accompanying drawings. For those skilled in the art, all other embodiments obtained without creative work are within the scope of protection of the present invention.

[0034] Under normal circumstances, when an open pit is excavated in steps below the groundwater level 4, it is affected by the filling of groundwater. When conventional methods cannot be used to excavate, the inventor adopts a method of laying out a shallow hole blasthole group 6 on the step 5 of the upper plate of the ore body and blasting them to form a temporary platform 7, on which a temporary water storage area 9 and a platform area 10 are divided; a deep hole blasthole group 8 is laid out in the temporary water storage area 9; a differential blasthole group 11 is laid out in the platform area 10, and the blasthole depth of the differential blasthole group is laid out in a rule of gradually deepening from close to the mudstone aquiclude to away from the mudstone aquiclude; the deep hole blasthole group is blasted to form an intercepting drainage pool 12, and the mudstone aquiclude serves as a water-blocking retaining wall of the intercepting drainage pool; the differential blasthole group is blasted to form an intercepting ditch 13 and a slope platform 14, and the intercepting drainage pool 12 The intercepting ditch 13 and the slope platform 14 are connected to form a pit bottom advance intercepting system; the groundwater in the pit bottom advance intercepting system is pumped out by the drainage system 16 to control the groundwater level and dig the ore body down to the pit bottom platform. Under the conception of this invention, there can be many specific embodiments:

[0035] Example 1, see Figures 1 to 8 ,

[0036] The indirect roof 1 of a sunken open pit is an aquifer, the roof 2 is a mudstone aquiclude, the ore body 3 is a weak aquifer, and the indirect roof 1 is the main water source of the pit. When the open pit is excavated below the groundwater level 4, the conventional method cannot be used due to the influence of groundwater filling. The method of the present invention can be used, and the specific steps are as follows:

[0037] (1) A shallow blast hole group 6 is constructed on the upper step 5 of the ore body. The diameter of each shallow blast hole is φ138 mm, the hole spacing is 6 m, the row spacing is 5 m, and the hole depth is controlled to be 50 cm above the groundwater level 4. After blasting, a temporary step 7 is formed.

[0038] (2) A temporary water storage area 9 and a platform area 10 are divided on the temporary steps 7. The length of the temporary water storage area 9 is 25 and the width is 10.

[0039] (3) a deep hole blast hole group 8 is arranged in the temporary water storage area, the diameter of each blast hole in the deep hole blast hole group is 138 mm, the hole spacing is 6 m, the row spacing is 5 m, and the hole depth is controlled at 15 m;

[0040] (4) Different blasthole groups 11 are arranged in the platform area 10, and the depth of the different blasthole groups is set from shallow to deep in a range of 10m. Figure 5 It can be seen that the shallow hole is close to the mudstone aquiclude, and the hole depth gradually deepens away from the mudstone aquiclude.

[0041] (5) blasting a deep hole blasthole group to form an interception and drainage pool 12, using a mudstone aquiclude as a water-blocking retaining wall of the interception and drainage pool to prevent groundwater from entering the ore body;

[0042] (6) The blasting differential blasthole group forms a water interception ditch 13 and a slope platform 14, which are connected to the interception and drainage pool 12 formed in step (5), and together form an advanced water interception system at the bottom of the pit, so that the groundwater flows to the interception and drainage pool;

[0043] (7) Using a drainage system such as a floating pump 16 to drain the groundwater, lower the groundwater level 4, and then mine the ore body until it reaches the designed pit bottom platform 15.

[0044] Example 2, see Figures 1 to 8 ,

[0045] The indirect roof 1 of a sunken open pit is an aquifer, the roof 2 is a mudstone aquiclude, the ore body 3 is a weak aquifer, and the indirect roof 1 is the main water source of the pit. When the open pit is excavated below the groundwater level 4, the conventional method cannot be used due to the influence of groundwater filling. The method of the present invention can be used, and the specific steps are as follows:

[0046] (1) A shallow blast hole group 6 is constructed on the upper step 5 of the ore body. The diameter of each shallow blast hole is φ138 mm, the hole spacing is 7 m, the row spacing is 6 m, and the hole depth is controlled to be 50 cm above the groundwater level 4. After blasting, a temporary step 7 is formed.

[0047] (2) A temporary water storage area 9 and a platform area 10 are divided on the temporary steps 7. The length of the temporary water storage area 9 is 30 m and the width is 12 m.

[0048] (3) A deep hole blast hole group is arranged in the temporary water storage area, the diameter of each blast hole in the deep hole blast hole group is 138 mm, the hole spacing is 7 m, the row spacing is 6 m, and the hole depth is controlled at 18 m;

[0049] (4) Different blasthole groups 11 are arranged in the platform area 10, and the depth of the different blasthole groups is set from shallow to deep in a range of 12m. Figure 5 It can be seen that the shallow hole is close to the mudstone aquiclude, and the hole depth gradually deepens away from the mudstone aquiclude.

[0050] (5) blasting a deep hole blasthole group to form an interception and drainage pool 12, using a mudstone aquiclude as a water-blocking retaining wall of the interception and drainage pool to prevent groundwater from entering the ore body;

[0051] (6) The blasting differential blasthole group forms a water interception ditch 13 and a slope platform 14, which are connected to the interception and drainage pool formed in step (5), and together form an advanced water interception system at the bottom of the pit, so that the groundwater flows to the interception and drainage pool;

[0052] (7) Use a drainage system such as a floating pump 16 to drain the groundwater and lower the groundwater level 4, then mine the ore body until it reaches the designed pit bottom platform.

[0053] Example 3, see Figures 1 to 8 ,

[0054] The indirect roof 1 of a sunken open pit is an aquifer, the roof 2 is a mudstone aquiclude, the ore body 3 is a weak aquifer, and the indirect roof 1 is the main water source of the pit. When the open pit is excavated below the groundwater level 4, the conventional method cannot be used due to the influence of groundwater filling. The method of the present invention can be used, and the specific steps are as follows:

[0055] (1) A shallow blast hole group 6 is constructed on the upper step 5 of the ore body. The diameter of each shallow blast hole is φ138 mm, the hole spacing is 8 m, the row spacing is 6 m, and the hole depth is controlled to be 50 cm above the groundwater level 4. After blasting, a temporary step 7 is formed.

[0056] (2) A temporary water storage area 9 and a platform area 10 are divided on the temporary steps 7. The length of the temporary water storage area 9 is 35 m and the width is 15 m.

[0057] (3) A deep hole blast hole group is arranged in the temporary water storage area, the diameter of each blast hole in the deep hole blast hole group is 138 mm, the hole spacing is 8 m, the row spacing is 6 m, and the hole depth is controlled at 20 m;

[0058] (4) Different blasthole groups are arranged in the platform area, and the depth of the different blasthole groups is set from shallow to deep in the range of 15m. Figure 5 It can be seen that the shallow hole is close to the mudstone aquiclude, and the hole depth gradually deepens away from the mudstone aquiclude.

[0059] (5) blasting a deep hole blasthole group to form an interception and drainage pool 12, using a mudstone aquiclude as a water-blocking retaining wall of the interception and drainage pool to prevent groundwater from entering the ore body;

[0060] (6) The blasting differential blasthole group forms a water interception ditch 13 and a slope platform 14, which are connected to the interception and drainage pool formed in step (5), and together form an advanced water interception system at the bottom of the pit, so that the groundwater flows to the interception and drainage pool;

[0061] (7) Using a drainage system such as a floating pump 16 to drain the groundwater, lower the groundwater level 4, and then mine the ore body until it reaches the designed pit bottom platform 15. Example

[0062] If you want to continue digging on the basis of the above embodiment, you can preset two or more pit bottom platforms. According to the implementation steps of the above embodiment, when the ore body is mined to the first pit bottom platform, the water-blocking retaining wall above the first pit bottom platform is broken, and the underground water in the interception and drainage pool is placed in the pit bottom platform, and then all the steps of the above embodiment are repeated to dig the ore body down to the second pit bottom platform. In this way, the ore body can reach any preset pit bottom platform. The specific implementation steps are as follows:

[0063] (1) Preset the pit bottom platform in two or more levels;

[0064] (2) A shallow blasthole group 6 is constructed on the upper step 5 of the ore body. After blasting, a temporary step 7 is formed. The hole depth of the shallow blasthole group is controlled to be 50 cm above the groundwater level 4. A temporary water storage area 9 and a platform area 10 are divided on the temporary step. The length of the temporary water storage area is 25 to 35 m and the width is 10 to 15 m.

[0065] (3) a deep hole blast hole group 8 is arranged in the temporary water storage area, the diameter of each blast hole in the deep hole blast hole group is 138 mm, the hole spacing is 6 to 8 m, the row spacing is 5 to 6 m, and the hole depth is controlled at 15 to 20 m;

[0066] (4) a differential blasthole group 11 is arranged in the platform area 10, wherein the depth of each hole in the differential blasthole group is within the range of 10 to 15 m, and each hole in the differential blasthole group is arranged from shallow to deep in a direction from close to the mudstone aquifer to far away from the mudstone aquifer;

[0067] (5) blasting a deep hole blasthole group to form an interception and drainage pool 12, using a mudstone aquiclude as a water-blocking retaining wall of the interception and drainage pool to prevent groundwater from entering the ore body;

[0068] (6) The blasting differential blasthole group 11 forms a drainage ditch 13 and a slope platform 14. The drainage ditch and the slope platform interception and drainage pool are connected to form a pit bottom advance water interception system, so that the groundwater flows to the interception and drainage pool;

[0069] (7) Using a drainage system such as a floating pump 16 to drain the groundwater and lower the groundwater level 4, the ore body is then mined until it reaches the first level of the designed pit bottom platform;

[0070] (8) Remove the water-blocking retaining wall above the first-level pit bottom platform, discharge the underground water in the interception and drainage pool 12 into the first-level pit bottom platform, move the drainage system such as the floating pump into the pit bottom, and then repeat the above steps (2) to (7) to excavate the ore body to the second-level designed pit bottom platform. In this way, the ore body can be excavated until the preset pit bottom platform.

[0071] It can be seen from the above embodiments that the method of the present invention can completely eliminate the flooding problem in open-pit mining, and is not difficult to implement and has low cost.

Claims

1. A method for digging down steps in a large open-pit mining pit, comprising the following steps: (1) The indirect roof of the open pit is an aquifer, the roof is a mudstone aquiclude, and the ore body is a weak aquifer; (2) Constructing a group of shallow blastholes on the upper wall step of the ore body in the aquifer, and forming a temporary step after blasting the shallow blasthole group; (3) Dividing the temporary steps described in step (2) into a temporary water tank area and a platform area; (4) Arranging a deep hole blasthole group in the temporary water storage area in step (3); arranging a differential blasthole group in the platform area, wherein the blasthole depth of the differential blasthole group is arranged in a direction from close to the mudstone aquiclude to far away from the mudstone aquiclude according to the rule of gradually deepening from shallow to deep; (5) The deep hole blast hole group in blasting step (4) forms an interception and drainage pool, and the mudstone impermeable layer in step (1) serves as a water-blocking retaining wall of the interception and drainage pool; the differential blast hole group in blasting step (4) forms an interception ditch and a slope platform, and the interception and drainage pool, the interception ditch and the slope platform are connected to form a pit bottom advance water interception system, so that underground water flows to the interception and drainage pool; (6) Pump out the groundwater in the interception and drainage pool, lower the groundwater level, and dig down the ore body to the platform at the bottom of the pit; The pit bottom platform is arranged in multiple levels. When the ore body is mined to the first pit bottom platform, the water-proof retaining wall above the first pit bottom platform is broken, and then the steps (1) to (6) are repeated to excavate the ore body until the second pit bottom platform. In this way, the ore body can be mined to any preset pit bottom platform.

2. The step-down digging method for a large open-pit mining pit according to claim 1 is characterized in that The depth of the shallow blasthole group is controlled above the groundwater level.

3. The step-down digging method for a large open-pit mining pit according to claim 2 is characterized in that The depth of the shallow blasthole group is controlled to be 50 cm above the groundwater level.

4. The step-down digging method for a large open-pit mining pit according to claim 1 is characterized in that The diameter of each hole in the shallow blasthole group is φ110mm~φ150mm, the hole spacing is 6~8m, and the row spacing is 5~6m.

5. The step-down digging method for a large open-pit mining pit according to claim 1 is characterized in that The temporary water storage area has a length of 25 to 35 m and a width of 10 to 15 m.

6. The step-down digging method for a large open-pit mining pit according to claim 1 is characterized in that In step (4), the diameter of each hole in the deep hole blast hole group is 138 mm, the hole spacing is 6 to 8 m, the row spacing is 5 to 6 m, and the hole depth is controlled at 15 to 20 m.

7. The step-down digging method for a large open-pit mining pit according to claim 1 is characterized in that The hole depths of the differential blasthole groups in step (4) are set from shallow to deep in the range of 10 to 15 m.

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