A method and system for combined bench and steep slope mining in an open pit mine

Abstract

The present application relates to the technical field of open-pit mining, in particular to a combined bench steep slope mining method and system for open-pit mine, which comprises the following steps: dividing multiple to-be-mined benches of the open-pit mine from top to bottom into multiple combined units; forming bench groups meeting the requirement of target working slope angle according to the operation capacity parameters of mining and loading equipment; performing separate operation on the multiple combined units; after each combined unit completes the current stage operation, the operation function thereof is transferred to the adjacent combined unit according to the preset order, so as to realize the cyclic advancement of the working face from top to bottom; and arranging the transport pit line on the non-working slope side or the bench which is not operated temporarily according to the advancement direction of the working line and the arrangement form of the combined bench. According to the scheme of the present application, the early-stage stripping amount is effectively postponed, the production stripping ratio is dynamically balanced, and the operation space occupation is reduced.

Description

Technical Field

[0001] This invention relates to the field of open-pit mining technology. More specifically, this invention relates to a method and system for combined bench steep slope mining in open-pit mines. Background Technology

[0002] In open-pit mining, especially during the transition from hillside open-pit to sunken open-pit mining, the working space in the lower part of the stope becomes increasingly limited as the mining depth increases, and the stripping ratio shows a sharp upward trend. Traditional mining methods (such as multi-bench full-width advance methods with working faces on each bench), although simple in process organization, result in relatively gentle working slope angles (usually below 20°), leading to a huge amount of rock stripping in the early stages of mining. A large amount of capital is thus tied up in the initial stripping work for a long period, requiring long working lines and large land occupation areas, exacerbating the difficulties in land acquisition and the initial financial pressure on the mine.

[0003] On the other hand, while existing steep slope mining techniques attempt to increase the slope angle by leaving narrower safety and cleaning platforms, their flexibility in dynamically adjusting the stripping relationship and their ability to expand the working face remain insufficient in actual high-intensity advances and rapid descent scenarios. Existing technologies struggle to achieve a significant and controllable increase in the working slope angle while ensuring safe production, and cannot effectively delay the stripping peak, making mine production highly susceptible to a passive situation of imbalance between mining and stripping.

[0004] Based on this, the current focus remains on addressing the difficulties in improving the slope angle and the inability to achieve an effective balance in the stripping and mining relationship. Summary of the Invention

[0005] In order to safely and efficiently increase the working slope angle, dynamically balance the stripping ratio, and reduce upfront investment and land occupation within a limited working space, this invention provides solutions in the following aspects.

[0006] In a first aspect, the present invention provides a method for combined bench steep slope mining in open-pit mines, comprising the following steps: S1, dividing multiple benches to be mined in the open-pit mine from top to bottom into multiple combined units, each combined unit containing multiple adjacent benches; at the same time, only some benches in each combined unit serve as working platforms with both mining and transportation functions, while the remaining benches serve as transportation channels or safety platforms; S2, determining the minimum width of the working platforms according to the operating capacity parameters of the mining and loading equipment, and determining the width of the non-working platforms according to the passage requirements of transportation vehicles, so that each combined unit forms a platform in the vertical direction that meets the target working slope angle requirements. S3, the multiple combined units are divided into working operations, wherein the combined units located at the top perform side-supporting operations to form the final slope, the combined units located in the middle perform side-expanding operations to expand the working face, and the combined units located at the bottom perform trenching or lowering operations to form new mining benches; after each combined unit completes the current stage of operation, its work function is transferred to the adjacent combined units in a preset order to realize the cyclical advancement of the working face from top to bottom; S4, according to the direction of the working line advancement and the arrangement of the combined benches, the transport pit line is arranged on the non-working side or the benches that are not currently being operated, and is dynamically moved as the working line advances and the functions of the combined units are rotated.

[0007] Furthermore, in step S1, each of the combined units contains four adjacent steps; within the same combined unit, the first and third steps alternately serve as a working platform, and the second and fourth steps serve as a transport channel or safety platform.

[0008] Furthermore, in step S2, the minimum width of the working platform is determined based on the standing horizontal digging radius of the excavator in the main mining and loading equipment, satisfying that: the minimum width of the working platform is 1 to 1.5 times the standing horizontal digging radius of the excavator.

[0009] Furthermore, the excavator has a standing horizontal digging radius of 13.5m, and the minimum width of the working platform is 20m.

[0010] Furthermore, in step S2, the width of the non-working platform is determined according to the safety passage requirements of a single transport vehicle, and its width ranges from 7.1m to 10m.

[0011] Further, in step S2, the height of a single step is 15m, and the target working slope angle is 30°; the target working slope angle is determined by the following method: based on the total vertical height of the combined unit and the horizontal projection width of only one working plate retained in the combined unit, it is calculated through geometric relationships.

[0012] Furthermore, the specific sequence of the cyclical operation described in step S3 is as follows: First, the lowest combined unit completes the trenching and lowering of the section to form the initial working face and prepare the ore volume; then the focus of the operation shifts to the adjacent combined unit above it to carry out the side-expanding operation, creating space for the next trenching and lowering of the lowest combined unit; at the same time, the highest combined unit carries out the side-adjusting operation; each combined unit repeats the above pattern to realize the continuous downward pushing and expansion of the working side.

[0013] Furthermore, in step S3, the steps in the combined unit that are not currently in operation serve as a buffer platform for blasted rock blocks to intercept rolling stones and flying rocks generated by the blasting of the upper steps, thereby reducing the safety impact on the lower transport pit line and the workers.

[0014] Furthermore, the method is applicable to the transition phase from hillside open-pit mining to depression open-pit mining.

[0015] In a second aspect, the present invention also provides an open-pit mine combined bench steep slope mining system, comprising: a bench grouping module, used to divide multiple benches to be mined in the open-pit mine from top to bottom into multiple combined units, each combined unit containing multiple adjacent benches, and configuring a working platform and a transportation / safety platform in each combined unit; a parameter design module, used to determine the minimum width of the working platform according to the operating capacity parameters of the mining and loading equipment, determine the width of the non-working platform according to the passage requirements of transportation vehicles, and calculate the target working slope angle; a cyclic operation control module, used to control each combined unit to perform side-adjusting operation, side-expanding operation, and trenching and section-lowering operation respectively, and realize the transfer of operation functions between adjacent combined units in a preset order; and a transportation system configuration module, used to arrange transportation pit lines on non-working sides or benches that are not currently in operation, and dynamically move the transportation system as the working line advances and the functions of the combined units rotate.

[0016] The beneficial effects of this invention are as follows: By grouping multiple benches and retaining only a few working faces, this invention effectively reduces the total width of the working platform at the same time. The increased working slope angle postpones the stripping of a large amount of upper rock and soil, reducing infrastructure investment and stripping pressure in the early stages of mine production. Benches that are not currently in operation within the combined benches can serve as buffer platforms for blasted rock blocks, reducing the impact of flyrock on the lower transport pit line and improving operational safety. Simultaneously, the larger working slope angle shortens the internal transport distance within the stope, reducing transportation costs. Attached Figure Description

[0017] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0018] Figure 1 This is a flowchart of an open-pit mine combined bench steep slope mining method according to an embodiment of the present invention; Figure 2 These are comparison diagrams of the mining effects and cross-sections before and after combined bench steep slope mining according to an embodiment of the present invention; Figure 3 This is a schematic cross-sectional view of the layout of the mining area in a combined bench steep slope mining according to an embodiment of the present invention. Figure 4 This is a field application effect diagram of the combined bench steep slope mining method of the present invention. Detailed Implementation

[0019] 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, not all, of the embodiments of the present invention. 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.

[0020] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Figure 1 This is a flowchart of an open-pit mine combined bench steep slope mining method according to an embodiment of the present invention.

[0022] like Figure 1 As shown, this invention provides a method for combined bench-style steep slope mining in open-pit mines. This method is applicable to the transition stage from hillside open-pit mining to depression open-pit mining. The method mainly includes the following steps: S1, bench grouping: The open-pit mine is divided into multiple mining benches from top to bottom into multiple combined units. Each combined unit contains multiple adjacent benches. At the same time, only some benches in each combined unit serve as working platforms that combine mining and transportation functions, while the remaining benches serve as transportation channels or safety platforms.

[0023] In some embodiments, each of the combined units includes four adjacent steps; within the same combined unit, the first and third steps alternately serve as a working platform, and the second and fourth steps serve as a transport channel or safety platform.

[0024] S2, Parameter Design: Based on the operating capacity parameters of the mining and loading equipment, determine the minimum width of the working platform and the width of the non-working platform according to the passage requirements of transport vehicles, so that each combined unit forms a step group that meets the target working slope angle requirements in the vertical direction.

[0025] In some embodiments, the minimum width of the working platform is determined based on the horizontal digging radius of the excavator in the main loading and unloading equipment, satisfying the following condition: the minimum width of the working platform is 1 to 1.5 times the horizontal digging radius of the excavator. Specifically, if the horizontal digging radius of the excavator is 13.5m, the minimum width of the working platform is 20m. The width of the non-working platform is determined based on the safe passage requirements of a single transport vehicle, and its width ranges from 7.1m to 10m.

[0026] The height of a single step is 15m, and the target working slope angle is 30°. The target working slope angle is determined by the following method: based on the total vertical height of the combined unit and the horizontal projection width of only one working plate retained in the combined unit, it is calculated through geometric relationships.

[0027] S3, Cyclic Operation: The multiple combined units are divided into work operations, wherein the combined units located at the top perform the side-supporting operation to form the final slope, the combined units located in the middle perform the side-expanding operation to expand the working face, and the combined units located at the bottom perform the trenching or lowering operation to form a new mining bench; after each combined unit completes the current stage of operation, its work functions are transferred to the adjacent combined units in a preset order to realize the cyclic advancement of the working face from top to bottom.

[0028] In some embodiments, the specific order of the cyclical jobs is as follows: First, the lowest combined unit completes the trenching and lowering section to form the initial working face and the ore preparation volume; The focus of the work then shifted to the adjacent combined unit above it for widening operations, creating space for the next trenching and lowering of the lowest combined unit; At the same time, the uppermost assembly unit performs a support operation; Each combined unit cycles through the above pattern, enabling the continuous pushing and expansion of the work assistant.

[0029] Furthermore, the steps in the aforementioned combined unit that are not currently in operation serve as buffer platforms for blasted rock blocks, intercepting rolling stones and flying rocks generated by the blasting of the upper steps, thereby reducing the impact on the safety of the lower transport pit line and the workers.

[0030] S4, Transportation System Layout: Based on the direction of the work line and the layout of the combined steps, transportation pit lines are laid out on the non-working side or steps that are not currently in operation, and are dynamically moved as the work line advances and the functions of the combined units change.

[0031] Furthermore, based on the above method, the present invention also provides an open-pit mine combined bench steep slope mining system, which includes a bench grouping module, a parameter design module, a cyclic operation control module, and a transportation system configuration module.

[0032] The bench grouping module is used to divide multiple benches to be mined in an open-pit mine from top to bottom into multiple combination units. Each combination unit contains multiple adjacent benches and is equipped with a working platform and a transportation / safety platform within each combination unit. The parameter design module is used to determine the minimum width of the working platform based on the operating capacity parameters of the mining and loading equipment, determine the width of the non-working platform based on the passage requirements of transport vehicles, and calculate the target working slope angle. The cyclic operation control module is used to control each combined unit to perform side-supporting operation, side-widening operation, and trenching and lowering operation respectively, and to realize the transfer of operation functions between adjacent combined units in a preset order; The transportation system configuration module is used to arrange transportation pit lines on non-working sides or steps where operations are temporarily suspended, and to dynamically relocate the transportation system as the work line advances and the functions of the combined units change.

[0033] According to the above-mentioned solution of the present invention, by grouping the benches and strictly limiting the number of working platforms in the same period, the total width of non-working platforms is significantly reduced. Compared with traditional multi-bench full-width mining, the present invention can increase the working slope angle by 8°~10° (e.g., from 20° to 30°), greatly shortening the required working line length and operating space occupation at the same mining depth. The increase in the working slope angle allows for the postponement of a large amount of upper rock and soil stripping work, effectively alleviating the infrastructure investment pressure in the early stage of mine production. The mine can dynamically adjust the stripping intensity according to market supply and demand and price fluctuations to achieve optimal control of the production stripping ratio. The platforms in the combined benches that are not currently in operation can act as blasting buffer platforms to block the impact of flying rocks on the lower transportation lines. Steep slope mining shortens the internal transportation distance of the stope, reduces mining transportation costs, and at the same time reduces the land acquisition area and shortens the slope exposure service time, which is conducive to the long-term stability of the slope.

[0034] The solution of the present invention will now be described in detail with reference to specific applications.

[0035] This embodiment uses the actual application of the Kunyang Phosphate Mine No. 2 in Yunnan Province as an example to illustrate the specific implementation process and technical effects of the present invention. When this mine transitioned from hillside open-pit mining to sunken open-pit mining, it faced technical challenges such as shrinking working space, increased stripping ratio, and the need to quickly prepare production capacity for subsequent underground mining. This provides a typical scenario for the application of the present invention.

[0036] 1. Case Background: The original design of the Kunyang Phosphate Mine No. 2 mining area adopted a multi-step full-width advance method with a working slope angle of approximately 20°. As the mining depth increased, the required working line length reached 250m when mining reached the 100m level. The working space was tight, the initial stripping pressure was enormous, and the production stripping ratio fluctuated in a saddle shape, making it difficult to meet the planning requirements of rapid production and seamless underground mining.

[0037] 2. Specific implementation steps of the method of the present invention: Step S101: Divide the 15m high benches within the stope into independent combination units of four (M=4). A total of three such combination units (N=3) are formed vertically across the entire stope. Within each combination unit, only one bench is used as the working platform at any given time, undertaking core operations such as drilling, blasting, and loading; the remaining three benches serve as transport platforms or safety platforms, providing only transport passages and safety features.

[0038] Step S102: Key parameter optimization design. The determination of parameters is the core of achieving the steep slope mining effect of this invention: 1) Step height (H): Taking into account the stability of the ore and rock, the maximum digging height of the hydraulic shovel, and safety regulations, it is determined to be 15m.

[0039] 2) Minimum width of the working platform (Bw): Designed based on the standing horizontal digging radius Rwz = 13.5m of the main mining and loading equipment (PC1250 hydraulic excavator). To meet the requirements for the equipment's single digging width, slewing, and truck loading space, a width coefficient k = 1.5 is taken, resulting in Bw = 1.5. 13.5m ≈ 20m. This width has been verified in practice to ensure efficient and safe operation of the equipment. 3) Non-working platform width (Bt): Designed for safe passage of a single mining truck (approximately 3m wide), with a safe distance of 3.5m between the truck body and the bottom line of the ramp, the minimum safe width Bt is calculated as 3m + 2m. 3.5m = 10m. This width is minimized while ensuring transportation safety. 4) Target working slope angle (α): Based on the above parameters (combined unit vertical height 60m, only one 20m wide working platform), the working slope angle can be stably increased to 30° through geometric calculations.

[0040] Step S103: Divide the three combined units into three working areas: upper, middle, and lower, and implement a cyclical operation mode of lower unit trenching, middle unit side widening, and upper unit side support: Initial preparation: Trenching work is carried out on the first step of the lowest combination (the third combination) to form the initial working line and working space.

[0041] Cyclic progression: Lower assembly (assembly 3): Mining and stripping operations are carried out in the initial trench. After completing one layer, the working platform is moved to the third step in this assembly as planned.

[0042] The middle section (section 2): Simultaneous expansion operations are carried out, on the one hand to prepare space for the continuous descent of the lower section, and on the other hand to produce a large amount of ore, which is the main production force in the current period.

[0043] Upper section (section 1): Perform side-supporting work, gradually advancing to the final boundary line to form a stable slope.

[0044] Functional rotation: When the lower combination reaches a certain depth, the expansion work of the middle combination creates new space for it. At this time, the center of gravity of the work shifts downward, and the original middle combination gradually turns to the support work. The new expansion work is carried out in the previous combination. This cycle is repeated to realize the continuous and rapid downward push of the work support.

[0045] Step S104: On the non-working side, a straight-line transport route is arranged using a 10m wide step as a safety platform. As the working platform advances and the functions of the combined units rotate, this transport system is periodically moved as a whole to a stable platform on the next higher level where the support work has been completed, always maintaining optimal connection with the active working platform.

[0046] 3. Implementation Results like Figure 2 As shown, the upper part is the traditional mining state (before combination): it shows that each step (step 1, step 2, step 3, step 4) is advanced independently and retains a wide working platform, resulting in a relatively gentle overall working slope angle. A large amount of rock in the upper part needs to be stripped in advance, forming a large stripping volume.

[0047] The lower part shows the mining state of the present invention (after assembly): multiple steps (step one to step four) are integrated into a combined unit, retaining only a very few necessary working platforms, and greatly reducing the width of non-working platforms.

[0048] Figure 2 The invention clearly demonstrates that, under the same unit advance volume, by increasing the working slope angle, it significantly reduces the "stripping volume generated by the combined benches" in the early stage; at the same mining depth, it achieves a longer "multi-advance distance" in the lower part, indicating that the advance speed of the lower working face in the mining area is accelerated and the space utilization efficiency is greatly improved.

[0049] like Figure 3 As shown, in the mining profile along line A-A', steps one, three, and five within the combined unit serve as working platforms, while steps two, four, and six serve as working platforms. The working platforms are clearly divided into penetration and blasting zones and mining and loading zones, achieving an efficient and alternating spatial arrangement.

[0050] The internal platform is distributed in an alternating manner: the cross-section shows the structural distribution of platform one to platform six from top to bottom. Among them, platform one, platform three, and platform five are marked as "Platform awaiting operation / Platform awaiting operation" and are used as non-working platforms (transportation or safety platforms); platform two, platform four, and platform six are marked as "Operating platform / Operation" and undertake the main mining and stripping functions.

[0051] Functional zoning of the working platform: On the active working platform (such as step 2, step 4, and step 6), it is divided into "drilling and blasting zone" (for drilling and blasting operations) and "mining and loading zone" (for loading and transporting ore and rock operations) according to the work process along the advancing direction, which shows the efficient and orderly production space organization structure inside the combined unit.

[0052] like Figure 4 The image shows a real-world application of this invention in the Kunyang Phosphate Mine No. 2 mining area. Significant technical and economic benefits have been achieved through the application of the combined bench optimization mining method of this invention. The working slope angle has been significantly increased: from the original design of 20° to a stable 30°.

[0053] Efficient use of working space: When mining to a depth of 100m, the required working line length is reduced significantly from about 250 meters in the traditional method to about 136 meters. More equipment can be arranged in the same working space, and the mining intensity is increased by about 30%.

[0054] Dynamic equilibrium of stripping-to-mining ratio: The stripping volume of approximately 3 million cubic meters before reaching full production capacity was successfully delayed, reducing initial investment pressure and production costs, stabilizing the production stripping-to-mining ratio curve, and achieving peak shaving and valley filling.

[0055] Improved overall benefits: The average transportation distance within the mining area is reduced by about 5.6%, the land acquisition area is reduced, and the service life of the slope is shortened, which is conducive to long-term stability.

[0056] In the description of this specification, "multiple" or "several" means at least two, such as two, three or more, unless otherwise explicitly specified.

[0057] While this specification has shown and described numerous embodiments of the invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of this invention.

Claims

1. A method for combined bench and steep slope mining in open-pit mines, characterized in that, Includes the following steps: S1 divides the multiple mining benches in the open-pit mine from top to bottom into multiple combined units. Each combined unit contains multiple adjacent benches. At the same time, only some benches in each combined unit serve as working platforms that combine mining and transportation functions, while the remaining benches serve as transportation channels or safety platforms. S2, determine the minimum width of the working platform according to the operating capacity parameters of the mining and loading equipment, and determine the width of the non-working platform according to the passage requirements of transport vehicles, so that each combined unit forms a step group that meets the target working slope angle requirements in the vertical direction; S3, the multiple combined units are divided into work operations, wherein the combined units located at the top perform the side-supporting operation to form the final slope, the combined units located in the middle perform the side-expanding operation to expand the working face, and the combined units located at the bottom perform the trenching or lowering operation to form a new mining bench; after each combined unit completes the current stage of operation, its work functions are transferred to the adjacent combined units in a preset order to realize the cyclical advancement of the working face from top to bottom; S4, based on the direction of the work line and the arrangement of the combined steps, arrange the transport pit line on the non-working side or the steps that are not currently in operation, and dynamically move it as the work line advances and the functions of the combined units change.

2. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, In step S1, each of the combined units contains four adjacent steps; within the same combined unit, the first and third steps alternately serve as a working platform, and the second and fourth steps serve as a transport channel or safety platform.

3. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, In step S2, the minimum width of the working platform is determined based on the standing horizontal digging radius of the excavator in the main mining and loading equipment, satisfying the following: the minimum width of the working platform is 1 to 1.5 times the standing horizontal digging radius of the excavator.

4. The open-pit mine combined bench steep slope mining method according to claim 3, characterized in that, The excavator has a standing horizontal digging radius of 13.5m and a minimum width of 20m for the working platform.

5. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, In step S2, the width of the non-working platform is determined according to the safety requirements for single-vehicle passage of transport vehicles, and its width ranges from 7.1m to 10m.

6. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, In step S2, the height of a single step is 15m, and the target working slope angle is 30°. The target working slope angle is determined by the following method: based on the total vertical height of the combined unit and the horizontal projection width of only one working plate retained in the combined unit, it is calculated through geometric relationships.

7. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, The specific sequence of the cyclical operations described in step S3 is as follows: First, the lowest combined unit completes the trenching and lowering section to form the initial working face and the ore preparation volume; The focus of the work then shifted to the adjacent combined unit above it for widening operations, creating space for the next trenching and lowering of the lowest combined unit; At the same time, the uppermost assembly unit performs a support operation; Each combined unit cycles through the above pattern, enabling the continuous pushing and expansion of the work assistant.

8. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, In step S3, the steps in the combined unit that are not currently in operation serve as a buffer platform for blasted rock blocks to intercept rolling stones and flying rocks generated by the blasting of the upper steps, thereby reducing the safety impact on the lower transport pit line and the workers.

9. The open-pit mine combined bench steep slope mining method according to claim 1, characterized in that, The method is applicable to the transition phase from hillside open-pit mining to depression open-pit mining.

10. A combined bench steep slope mining system for open-pit mines, characterized in that, include: The bench grouping module is used to divide multiple benches to be mined in an open-pit mine from top to bottom into multiple combination units. Each combination unit contains multiple adjacent benches and is equipped with a working platform and a transportation / safety platform within each combination unit. The parameter design module is used to determine the minimum width of the working platform based on the operating capacity parameters of the mining and loading equipment, determine the width of the non-working platform based on the passage requirements of transport vehicles, and calculate the target working slope angle. The cyclic operation control module is used to control each combined unit to perform side-supporting operation, side-widening operation, and trenching and lowering operation respectively, and to realize the transfer of operation functions between adjacent combined units in a preset order; The transportation system configuration module is used to arrange transportation pit lines on non-working sides or steps where operations are temporarily suspended, and to dynamically relocate the transportation system as the work line advances and the functions of the combined units change.

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