Open well collaborative mining method for metal surface mine bottom boundary isolation pillars

Abstract

The invention discloses an open well collaborative mining method for a metal surface mine bottom boundary isolation pillar, and belongs to the technical field of mining, the open well collaborative mining method comprises the following steps: stoping the exposed part of the boundary isolation pillar with the vertical thickness of not more than 8m by adopting an open-pit mining mode; when the vertical thickness is more than 8m, blasting and stoping by adopting an upward hole blasting mode in a bottom pit of the boundary isolation ore pillar or a combined mode of upward hole blasting in the bottom pit and downward hole blasting at the bottom of an open pit; for the part, not exposed at the bottom of the open pit, of the boundary isolation ore pillar and the part, with the thickness smaller than 5 m, of the surrounding rock on the upper portion of the boundary isolation ore pillar, the surrounding rock on the upper portion is peeled off firstly, and then blasting stoping is conducted in the mode of upward hole blasting in the bottom pit or the combination of upward hole blasting in the bottom pit and downward hole blasting at the bottom of the open pit of the boundary isolation ore pillar; and the upper surrounding rock with the thickness smaller than 5 m is stoped by adopting a sublevel open-stoping subsequent filling continuous mining method. The advantages of open-pit mining and underground mining are combined, and the recovery efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mining, and particularly to an open-pit and underground collaborative mining method for the bottom boundary isolation pillar of a metal open-pit mine. Background Art

[0002] With the continuous increase in the depth of mineral resource development, the open-pit to underground combined mining mode has been widely applied in the mining industry. During the open-pit and underground collaborative mining stage, in order to achieve safe operation isolation, the technical measure of leaving an open-pit boundary isolation pillar is generally adopted. However, as a temporary security structure, this pillar has been in a state of overlying for a long time, resulting in the permanent loss of a large amount of high-quality mineral resources and significantly reducing the overall resource utilization rate of the mine.

[0003] In recent years, although domestic and foreign scholars have carried out preliminary research on the recovery technology of boundary isolation pillars, the relevant achievements mainly focus on the field of steeply inclined ore bodies, and the recovery of pillar resources is realized by means of sublevel caving, longhole retreating mining, etc. For gently inclined ore bodies, the existing mining methods have technical bottlenecks such as difficult control of stope stability, high ore dilution rate, and limited mechanized operation, and a safe and efficient mining process system has not been formed yet.

[0004] Therefore, an open-pit and underground collaborative mining method for the bottom boundary isolation pillar of a metal open-pit mine is proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide an open-pit and underground collaborative mining method for the bottom boundary isolation pillar of a metal open-pit mine, aiming to solve or improve at least one of the above technical problems.

[0006] To achieve the above purpose, the present invention provides the following solution: The present invention provides an open-pit and underground collaborative mining method for the bottom boundary isolation pillar of a metal open-pit mine, including: first, determining whether the gently inclined boundary isolation pillar is exposed at the bottom of the open-pit; for the exposed part, then determining the vertical thickness of the boundary isolation pillar; for the unexposed part, then determining the thickness of the upper surrounding rock of the boundary isolation pillar, and thus dividing into the following different mining methods according to different situations:

[0007] For the part of the boundary isolation pillar that is exposed at the bottom of the open-pit and the vertical thickness of the boundary isolation pillar does not exceed 8 m, the open-pit mining method is adopted for mining;

[0008] For the part of the boundary isolation pillar that is exposed at the bottom of the open-pit and the vertical thickness of the boundary isolation pillar is more than 8 m, the bottom in-pit upward hole blasting or the combination of bottom in-pit upward hole blasting and open-pit bottom downward hole blasting is adopted for blasting ore drawing, and the bottom in-pit ore drawing method is adopted for mining;

[0009] For the part of the boundary isolation pillar that is not exposed at the bottom of the open pit, and when the thickness of the upper surrounding rock of the boundary isolation pillar is less than 5 m, first strip the upper surrounding rock, and then use the combination of upward hole blasting in the bottom of the pit of the boundary isolation pillar or the combination of upward hole blasting in the bottom of the pit of the boundary isolation pillar and downward hole blasting at the bottom of the open pit for blasting ore drawing, and use the ore drawing method in the bottom of the pit for stoping;

[0010] For the part of the boundary isolation pillar that is not exposed at the bottom of the open pit, and when the thickness of the upper surrounding rock of the boundary isolation pillar is greater than 5 m, use the sublevel open stoping with subsequent filling continuous mining method for stoping.

[0011] Preferably, set the boundary isolation pillar to be in the north-south direction and inclined downward to the south. During open-pit mining, arrange an access trench on the north side of the ore body at the bottom of the open pit, develop the working face downward, and use the open-pit mining method to mine the ore body through the processes of drilling, blasting, mucking, transportation, and waste disposal.

[0012] Preferably, the implementation of the access trench needs to meet the basic conditions for the operation of trackless equipment, and the slope is controlled at 7-12°.

[0013] Preferably, for the part of the boundary isolation pillar that is already exposed at the bottom of the open pit, and when the vertical thickness of the boundary isolation pillar (7) is more than 8 m, it is subdivided into two mining methods:

[0014] For the vertical thickness of the boundary isolation pillar within 10-15 m, use the upward hole blasting in the bottom of the pit of the boundary isolation pillar for blasting ore drawing, and use the ore drawing method in the bottom of the pit for stoping;

[0015] For the vertical thickness of the boundary isolation pillar exceeding 15 m, use the combination of downward hole blasting at the bottom of the open pit and upward hole blasting in the bottom of the pit of the boundary isolation pillar for blasting, and use the method of drawing ore by undercutting in the bottom of the pit for stoping.

[0016] Preferably, when using the upward hole blasting in the bottom of the pit of the boundary isolation pillar for blasting ore drawing, arrange development headings, ore-drawing headings, and drilling headings in the bottom of the pit, construct upward fan-shaped medium-deep hole side blasting in the bottom of the pit, and draw ore by undercutting.

[0017] Preferably, when using the combination of downward hole blasting at the bottom of the open pit and upward hole blasting in the bottom of the pit of the boundary isolation pillar for blasting ore drawing, arrange development headings, ore-drawing headings, and drilling headings in the bottom of the pit, construct downward large-diameter deep hole side blasting at the bottom of the open pit, construct upward fan-shaped medium-deep hole side blasting in the bottom of the pit, and draw ore by undercutting.

[0018] Preferably, when constructing upward fan-shaped medium-deep holes in the bottom of the pit, the distance between the bottom of the hole and the bottom of the open pit is not less than the preset spacing.

[0019] Preferably, in the method of retreating mining by the sublevel open stoping with subsequent backfilling, when mining each section of the ore body, the ore is blasted and caved by the combination of upward holes blasting at the bottom of the boundary isolation pillar in the pit or the combination of upward holes blasting at the bottom of the boundary isolation pillar in the pit and downward holes blasting under the open pit bottom, and mined by the way of ore drawing at the bottom of the pit.

[0020] Preferably, when the vertical distance between the ore body of the boundary isolation pillar and the bottom of the open pit exceeds the preset distance, only the upward holes blasting at the bottom of the boundary isolation pillar in the pit is used for blasting and ore drawing.

[0021] Preferably, in the mining method of sublevel open stoping with subsequent backfilling, if the overlying surrounding rock is reserved, when constructing downward large-diameter deep holes for side blasting at the bottom of the open pit, no charge is placed at the top of the holes.

[0022] The present invention discloses the following technical effects:

[0023] (1) The present invention divides into different mining methods according to the outcropping situation of the gently inclined boundary isolation pillar at the bottom of the open pit, the vertical thickness of the boundary isolation pillar, and the thickness of the overlying surrounding rock of the boundary isolation pillar, and excellently solves the mining problems of gently inclined ore bodies under different burial depths.

[0024] (1) The present invention mines the ore body by the way of combined open-pit and underground mining, effectively combines the advantages of open-pit mining and underground mining, and effectively improves the efficiency of ore body retreating mining.

[0025] (3) The present invention is applicable to the mining of gently inclined ore bodies of the boundary isolation pillar at the bottom of the open pit, and can effectively increase the recovery amount of mine resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0027] Figure 1 is the schematic diagram of open-pit mining of the ore body outcropping at the bottom of the open pit in the present invention;

[0028] Figure 2 is the schematic diagram of mining by upward holes blasting at the bottom of the pit in the present invention;

[0029] Figure 3 is the schematic diagram of mining by the combination of upward holes blasting at the bottom of the pit and downward holes blasting under the open pit bottom in the present invention;

[0030] Figure 4 is the schematic diagram of mining in a one-step stope in the present invention;

[0031] Figure 5 is the schematic diagram of mining in a two-step stope in the present invention.

[0032] In the figure: 1. access trench; 2. drilling drift; 3. ore-drawing drift; 4. development drift; 5. retaining wall; 6. filling pipeline; 7. boundary isolation pillar; 8. bottom of open-pit Specific implementation mode

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation modes.

[0035] Refer to Figures 1 - 5 , the present invention provides a method for coordinated open-pit and underground mining of the bottom boundary isolation pillar of a metal open-pit mine, including:

[0036] First, judge whether the gently inclined boundary isolation pillar 7 is exposed at the bottom of the open-pit 8; for the exposed part, then judge the vertical thickness of the boundary isolation pillar 7; for the unexposed part, then judge the thickness of the upper surrounding rock of the boundary isolation pillar 7, and thus divide the following different mining methods according to different situations:

[0037] For the part of the boundary isolation pillar 7 that is exposed at the bottom of the open-pit 8 and the vertical thickness of the boundary isolation pillar 7 does not exceed 8 m, open-pit mining is used for stoping.

[0038] For the part of the boundary isolation pillar 7 that is exposed at the bottom of the open-pit 8 and the vertical thickness of the boundary isolation pillar 7 is more than 8 m, blasting ore drawing is carried out by the combination of upward holes blasting at the bottom of the boundary isolation pillar 7 in the pit or upward holes blasting at the bottom of the boundary isolation pillar 7 in the pit and downward holes blasting at the bottom of the open-pit 8, and stoping is carried out by the method of drawing ore from the bottom of the pit.

[0039] For the part of the boundary isolation pillar 7 that is not exposed at the bottom of the open-pit 8 and the thickness of the upper surrounding rock of the boundary isolation pillar 7 is less than 5 m, first peel off the upper surrounding rock, and then carry out blasting ore drawing by the combination of upward holes blasting at the bottom of the boundary isolation pillar 7 in the pit or upward holes blasting at the bottom of the boundary isolation pillar 7 in the pit and downward holes blasting at the bottom of the open-pit 8, and stoping is carried out by the method of drawing ore from the bottom of the pit.

[0040] For the part of the boundary isolation pillar 7 that is not exposed at the bottom of the open-pit 8 and the thickness of the upper surrounding rock of the boundary isolation pillar 7 is more than 5 m, sublevel open stoping with subsequent filling continuous mining method is used for stoping.

[0041] In some alternative embodiments, the boundary isolation ore pillar 7 is arranged in the north-south direction and slopes downward to the south. During open-pit mining, an access trench 1 is arranged on the north side of the ore body at the bottom of the open-pit 8, and the working face is developed downward. Through the processes of rock drilling, blasting, loading, transportation, and waste dumping, the ore body is mined by open-pit mining method.

[0042] In some alternative embodiments, the implementation of the access trench 1 needs to meet the basic conditions for the operation of trackless equipment, and the slope is controlled at 7 - 12°.

[0043] In some alternative embodiments, for the part of the boundary isolation ore pillar 7 that has emerged at the bottom of the open-pit 8 and the vertical thickness of the boundary isolation ore pillar 7 is more than 8m, it is subdivided into two mining methods:

[0044] For the vertical thickness of the boundary isolation ore pillar 7 within 10 - 15m, the bottom of the boundary isolation ore pillar 7 is blasted by upward holes in the pit for ore caving, and the ore is mined by the way of ore drawing from the bottom of the pit.

[0045] For the vertical thickness of the boundary isolation ore pillar 7 exceeding 15m, a combined method of downward hole blasting at the bottom of the open-pit 8 and upward hole blasting in the bottom of the boundary isolation ore pillar 7 is used for blasting, and the ore is mined by the way of drawing the bottom and ore drawing in the bottom of the pit.

[0046] In some alternative embodiments, when blasting and ore drawing are carried out by the way of upward hole blasting in the bottom of the boundary isolation ore pillar 7, a development drift 4, an ore-drawing drift 3, and a drilling drift 2 are arranged in the bottom of the pit. Upward fan-shaped medium-deep holes are constructed in the bottom of the pit for lateral blasting, and the bottom is drawn for ore drawing.

[0047] In some alternative embodiments, when blasting and ore drawing are carried out by a combined method of downward hole blasting at the bottom of the open-pit 8 and upward hole blasting in the bottom of the boundary isolation ore pillar 7, a development drift 4, an ore-drawing drift 3, and a drilling drift 2 are arranged in the bottom of the pit. Downward large-diameter deep holes are constructed in the bottom of the open-pit 8 for lateral blasting, and upward fan-shaped medium-deep holes are constructed in the bottom of the pit for lateral blasting, and the bottom is drawn for ore drawing.

[0048] Furthermore, a drilling drift 2 is arranged along the ore body strike at an appropriate position on the footwall of the ore body, a drift along the vein development drift 4 is arranged in parallel, and an ore-drawing drift 3 is arranged at a certain angle between the drilling drift 2 and the development drift 4. First, medium-deep hole cutting at the bottom is carried out, and then downward large-diameter deep hole shaft sinking and cutting are carried out. After the ore supply of the cut-off trench is completed, downward large-diameter deep hole lateral blasting and upward fan-shaped medium-deep hole lateral blasting are used for stoping.

[0049] Specifically, a drilling roadway 2 is arranged along the strike of the ore body at the footwall position of the ore body, with a width of 4 m and a height of 3.5 m; an along-strike development roadway 4 is arranged in parallel at a position about 10 - 14 m away from the drilling roadway 2, with a width of 4 m and a height of 3.5 m; an ore-drawing drift 3 is arranged between the drilling roadway 2 and the development roadway 4 at a certain angle, and the spacing between the ore-drawing drifts 3 is about 6 m, with a width of 4 m and a height of 3.5 m.

[0050] In some alternative embodiments, when drilling upward fan-shaped medium-deep holes in the bottom pit, the distance between the bottom of the holes and the bottom 8 of the open pit is not less than a preset spacing. That is to say, during the construction of medium-deep holes in the bottom pit, the bottom of the holes needs to be at a certain distance from the bottom 8 of the open pit to prevent piercing the ground surface and affecting the blasting efficiency.

[0051] Furthermore, downward large-diameter deep holes are drilled at the bottom 8 of the open pit, with a row spacing of 2.0 - 2.5 m, a hole spacing of 3.0 - 4.0 m, and a hole distance from the edge of 1.0 - 1.5 m. A rock drilling jumbo is used to drill upward fan-shaped medium-deep holes, with a row spacing of 1.5 - 1.8 m and a bottom hole distance of 1.8 - 2.2 m. Granular ammonium nitrate explosives are used for multi-row millisecond non-electric blasting, with 5 - 10 rows blasted each time; a 3 m 3 scraper is used for ore drawing, and a 3 m 3 remote-controlled diesel scraper is used to assist in recovering the residual ore at the bottom of the trench.

[0052] In some alternative embodiments, in the method of mining by sublevel open stoping with subsequent backfilling, when mining each section of the ore body, a combined blasting method of upward holes blasting at the bottom pit of the boundary isolation pillar 7 or a combination of upward holes blasting at the bottom pit of the boundary isolation pillar 7 and downward holes blasting at the bottom 8 of the open pit is used for blasting ore drawing, and the ore is drawn from the bottom pit.

[0053] In some alternative embodiments, when the vertical distance between the ore body of the boundary isolation pillar 7 and the bottom 8 of the open pit exceeds the preset distance, only the upward holes blasting method at the bottom pit of the boundary isolation pillar 7 is used for blasting ore drawing.

[0054] In some alternative embodiments, in the mining method of sublevel open stoping with subsequent backfilling, a combined blasting method of upward holes blasting at the bottom pit of the boundary isolation pillar 7 or a combination of upward holes blasting at the bottom pit of the boundary isolation pillar 7 and downward holes blasting at the bottom 8 of the open pit is used for blasting ore drawing.

[0055] In some alternative embodiments, if overlying surrounding rock is left, when conducting lateral blasting of downward large-diameter deep holes at the bottom 8 of the open pit, the top of the holes is not charged.

[0056] Furthermore, in the mining method of sublevel open stoping with subsequent backfilling, the boundary isolation pillar 7 is divided into a one-step stope and a two-step stope arranged at intervals, and the two-step stope is located between two adjacent one-step stopes. Two-step mining is carried out, and the stope span is adjusted according to the thickness of the overlying strata.

[0057] First, mine the first-step stope, and then mine the adjacent two second-step stopes. During mining, develop the preparatory roadway 2, ore-drawing drift 3, and drilling roadway 4. At the bottom of the open-pit 8, construct downward large-diameter long holes, and at the bottom, construct fan-shaped medium-deep holes for undercutting and ore drawing. If the ore body is too deep from the bottom of the open-pit 8, only use the medium-deep hole blasting at the bottom for ore drawing. After all the ore is transported out, promptly fill the mined-out area.

[0058] When the stoping of each ore room is completed, promptly carry out filling; for the first-step ore room, use low-strength tailings-cemented filling (cement-sand ratio 1:6 - 1:12), and construct a closed retaining wall 5 in the bottom ore-drawing drift 3 and the roadway connected to the mined-out area. The mined-out area of the first-step ore room must be filled up to the top. For the second-step ore room, first fill it with waste rock to 2 / 3 of the mined-out area, and when waste rock filling is no longer possible, then carry out classified tailings filling. The filling of waste rock and tailings can be flexibly adjusted according to production organization.

[0059] Example 1

[0060] In a certain metal mine, there are boundary isolation pillars for multi-layer gently inclined medium-thick to thick copper ore bodies occurring at the bottom of the open-pit. The specific implementation steps are as follows:

[0061] (1) For the part of the boundary isolation pillar that has been exposed, and for the ore body part where the vertical thickness from the bottom of the open-pit 8 to the ore body floor of the boundary isolation pillar does not exceed 5 - 8 m, use the open-pit mining method for stoping. That is, construct an access trench 1 from the footwall side of the ore body at the bottom of the open-pit, develop the working face downward, and through processes such as drilling, blasting, loading, transportation, and waste dumping, use the open-pit mining method to mine the ore body.

[0062] (2) For the part of the boundary isolation pillar that has been exposed, and when the vertical thickness from the bottom of the open-pit 8 to the ore body floor of the boundary isolation pillar is more than 8 - 10 m and is not suitable for open-pit mining, and when the vertical thickness is within 10 - 15 m and the ore body can be stoped only by using upward fan-shaped medium-deep hole side blasting in the bottom of the pit, use the method of medium-deep hole blasting in the pit for ore caving + ore drawing in the pit for stoping; at this time, mine the ore body covered with a relatively thin rock stratum together. That is, divide the ore body into two-step stopes, the first-step stope and the second-step stope. The boundary isolation pillar of the first-step stope has been exposed, and the second-step stope is covered with a relatively thin rock stratum. After open-pit stripping, carry out the ore body stoping work. During mining, arrange a cut trench and a cut shaft in the ore room. The width of the cut trench is 4.0 m, and the diameter of the cut shaft is φ2.0 m. First, carry out undercutting with medium-deep holes at the bottom, and the diameter of the medium-deep holes is 76 mm. Use a rock drilling jumbo to construct vertical fan-shaped medium-deep holes in the drilling roadway, with a row spacing of 1.8 m and a hole bottom spacing of 2.0 m. Use granular ammonium nitrate explosive and multi-row millisecond non-electric blasting, blasting 8 rows each time. Use a 3 m 3 scooptram for ore drawing, and use a 3 m 3The remotely controlled diesel LHD is used to assist in recovering the residual ore at the bottom of the trench. In the ore extraction of the two-step stope, it is necessary to separate the ore from the waste rock, and the ore is unloaded into the nearby stope chute. The filling pipeline 6 is arranged at the bottom of the open pit 8, and the stope is filled in time after the stoping is completed. The first-step stope is filled with low-strength tailings cement (cement-sand ratio 1:6 - 1:12). The closed retaining wall 5 is constructed in the bottom ore-drawing drift 3 and the roadway connected to the goaf. The first-step stope is filled up to the boundary of the bottom of the open pit. The second-step stope is first filled with waste rock up to 2 / 3 of the goaf, and then graded tailings are filled when the waste rock filling is no longer possible. The filling of waste rock and tailings can be flexibly adjusted according to production organization.

[0063] Only two stopes are arranged after the bottom of the open pit is opened up, and a 5m strike ore pillar is reserved between the stope where the bottom of the open pit is opened up and the stope where the bottom has not been opened up.

[0064] (3) For the parts with the surrounding rock thickness of 5 - 7m or more, the sublevel open stoping with subsequent filling continuous mining method is adopted for stoping. Two-step stopes are arranged along the dip and strike of the ore body. The first-step stope is mined first, and then the second-step stope. One cutting slot and one cutting raise are arranged in the stope. The width of the cutting slot is 4.0m, and the diameter of the cutting raise is φ2.0m. First, the bottom medium-deep holes are used for slotting, the diameter of the medium-deep holes is 76mm, and then the large-diameter downhole raises are expanded and slotted. After the ore supply of the cutting slot is completed, the large-diameter downhole holes are used for lateral blasting and the upward fan medium-deep holes are used for lateral blasting for stoping. The diameter of the large-diameter downhole holes is 165mm, the row spacing is 2.5m, the hole spacing is 4.0m, and the distance from the edge hole is 1.5m. The vertical fan medium-deep holes are constructed by a rock drilling jumbo, the row spacing is 1.8m, and the hole bottom distance is 2.0m. Granular ammonium nitrate explosive is used, and multi-row millisecond non-electric blasting is adopted, with 8 rows blasted each time. The 3m 3 LHD is used for ore drawing, and 3m 3 The remotely controlled diesel LHD is used to assist in recovering the residual ore at the bottom of the trench. In the ore extraction of the two-step stope, it is necessary to separate the ore from the waste rock, and the ore is unloaded into the nearby stope chute. The filling pipeline 6 is arranged in the upper sublevel drift, and the stope is filled in time after the stoping is completed. The first-step stope is filled with low-strength tailings cement (cement-sand ratio 1:6 - 1:12). The closed retaining wall 5 is constructed in the bottom ore-drawing drift 3 and the roadway connected to the goaf. The goaf of the first-step stope must be filled up to the roof. The second-step stope is first filled with waste rock up to 2 / 3 of the goaf, and then graded tailings are filled when the waste rock filling is no longer possible. The filling of waste rock and tailings can be flexibly adjusted according to production organization.

[0065] As the ore body dips downward and the buried depth increases continuously, it is not suitable to use open-pit downward hole blasting, and all are converted to bottom medium-deep hole blasting for ore drawing.

[0066] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0067] The embodiments described above are only for describing the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An open-pit and underground collaborative mining method for the bottom boundary isolation pillar in a metal open-pit mine, characterized in that, Including: First, determine whether the gently inclined boundary isolation ore pillar (7) is exposed at the bottom of the open pit (8); for the exposed part, then determine the vertical thickness of the boundary isolation ore pillar (7); for the unexposed part, then determine the thickness of the upper surrounding rock of the boundary isolation ore pillar (7), and thus divide into the following different mining methods according to different situations: For the part of the boundary isolation ore pillar (7) that is exposed at the bottom of the open pit (8) and the vertical thickness of the boundary isolation ore pillar (7) does not exceed 8 m, the open-pit mining method is adopted for stoping. For the part of the boundary isolation ore pillar (7) that is exposed at the bottom of the open pit (8) and the vertical thickness of the boundary isolation ore pillar (7) is more than 8 m, the combined method of upward hole blasting in the bottom of the boundary isolation ore pillar (7) or the combination of upward hole blasting in the bottom of the boundary isolation ore pillar (7) and downward hole blasting at the bottom of the open pit (8) is adopted for blasting ore caving, and the ore is extracted from the bottom of the pit for stoping. For the part of the boundary isolation ore pillar (7) that is not exposed at the bottom of the open pit (8) and the thickness of the upper surrounding rock of the boundary isolation ore pillar (7) is less than 5 m, first strip the upper surrounding rock, and then adopt the combined method of upward hole blasting in the bottom of the boundary isolation ore pillar (7) or the combination of upward hole blasting in the bottom of the boundary isolation ore pillar (7) and downward hole blasting at the bottom of the open pit (8) for blasting ore caving, and the ore is extracted from the bottom of the pit for stoping. For the part of the boundary isolation ore pillar (7) that is not exposed at the bottom of the open pit (8) and the thickness of the upper surrounding rock of the boundary isolation ore pillar (7) is greater than 5 m, the sublevel open stoping with subsequent filling continuous mining method is adopted for stoping.

2. The open-pit and underground collaborative mining method for the bottom boundary isolation ore pillar in a metal open-pit mine according to claim 1, characterized in that: It is assumed that the boundary isolation ore pillar (7) is in the north-south direction and slopes downward to the south. During open-pit mining, an access trench (1) is arranged on the north side of the ore body at the bottom of the open pit (8), the working face is developed downward, and the ore body is mined by the open-pit mining method through the processes of rock drilling, blasting, mucking, transportation, and waste disposal.

3. The open-pit and underground collaborative mining method for the bottom boundary barrier pillar in a metal open-pit mine according to claim 2, wherein: The implementation of the access trench (1) needs to meet the basic conditions for the operation of trackless equipment, and the slope is controlled at 7-12°.

4. The open-pit and shaft collaborative mining method for the bottom boundary isolation ore pillar in a metal open-pit mine according to claim 1, wherein: For the part of the boundary isolation ore pillar (7) that is exposed at the bottom of the open pit (8) and the vertical thickness of the boundary isolation ore pillar (7) is more than 8 m, it is further divided into two mining methods: For the vertical thickness of the boundary isolation ore pillar (7) within 10-15 m, the upward hole blasting method in the bottom of the boundary isolation ore pillar (7) is adopted for blasting ore caving, and the ore is extracted from the bottom of the pit for stoping. For the vertical thickness of the boundary isolation ore pillar (7) exceeding 15 m, the combined method of downward hole blasting at the bottom of the open pit (8) and upward hole blasting in the bottom of the boundary isolation ore pillar (7) is adopted for blasting, and the ore is extracted from the bottom of the pit after undercutting for stoping.

5. The open-pit and underground collaborative mining method for the bottom boundary isolation pillar in a metal open-pit mine according to claim 4, characterized in that: When the upward hole blasting method in the bottom of the boundary isolation ore pillar (7) is adopted for blasting ore extraction, the development headings (4), ore extraction headings (3), and rock drilling headings (2) are arranged in the bottom of the pit, and upward fan-shaped medium-deep hole side blasting is carried out in the bottom of the pit, and the ore is extracted after undercutting.

6. The open-pit and underground collaborative mining method for the bottom boundary isolation pillar in a metal open-pit mine according to claim 4, characterized in that: When blasting and ore drawing are carried out by combining downward hole blasting at the open-pit bottom (8) and upward hole blasting in the bottom pit of the boundary isolation pillar (7), development headings (4), ore-drawing headings (3), and drilling headings (2) are arranged in the bottom pit. Downward large-diameter deep-hole side blasting is constructed at the open-pit bottom (8), and upward fan-shaped medium-deep hole side blasting is constructed in the bottom pit for undercutting and ore drawing.

7. The open-pit and underground collaborative mining method for the bottom boundary isolation pillar in a metal open-pit mine according to claim 6, characterized in that: When constructing upward fan-shaped medium-deep holes in the bottom pit, the distance between the bottom of the holes and the open-pit bottom (8) is not less than the preset spacing.

8. The open-pit and underground collaborative mining method for the bottom boundary isolation ore pillar in a metal open-pit mine according to claim 1, characterized in that: In the method of stoping by sublevel open stoping with subsequent filling, when mining each section of the ore body, upward hole blasting in the bottom pit of the boundary isolation pillar (7) or a combination of upward hole blasting in the bottom pit and downward hole blasting at the open-pit bottom (8) is used for blasting and ore caving, and the ore is drawn from the bottom pit for stoping.

9. The open-pit and shaft collaborative mining method for the bottom boundary isolation pillar in a metal open-pit mine according to claim 8, wherein: When the vertical distance between the ore body of the boundary isolation pillar (7) and the open-pit bottom (8) exceeds the preset distance, only upward hole blasting in the bottom pit of the boundary isolation pillar (7) is used for blasting and ore drawing.

10. The open-pit and shaft collaborative mining method for the bottom boundary isolation ore pillar in a metal open-pit mine according to claim 8, characterized in that: In the method of stoping by sublevel open stoping with subsequent filling, if the overlying surrounding rock is left, when constructing downward large-diameter deep-hole side blasting at the open-pit bottom (8), the top of the hole is not charged.

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