A method of mining steeply inclined isolated pillars

Abstract

The present application relates to the technical field of underground mining of metal mines, and particularly relates to a mining method of steeply inclined isolated pillar. The present application designs a mining method of steeply inclined isolated pillar, which comprises a preparation process, a cutting process and a blasting process. The blasting parameters to be determined in the blasting process include a millisecond time, a blast hole density coefficient, a hole bottom distance, a collapse ore quantity of each row of blast holes, a charge quantity of each row and a total blast hole length. By controlling the blast hole arrangement conditions such as the blast hole density coefficient, the hole bottom distance, the collapse ore quantity of each row of blast holes, the charge quantity of each row and the total blast hole length, the ore lump size is adjusted to ensure that the ore flow velocity of the left side of the ore body is greater than that of the right side, the broken ore rock scatter in the upper right is prevented from being mixed in advance, the ore in both sides is finally mined at the same time, the dilution rate of the ore is reduced, and the influence on the left filling area is reduced by reasonably setting the millisecond time.

Description

Technical Field

[0001] This invention relates to the field of underground mining technology for metal mines, and in particular to a mining method for a steeply inclined isolation pillar. Background Technology

[0002] Steeply inclined pillars typically consist of a backfill body on the left and caving debris on the right, with a dip angle of 55–65°. Shallow-hole retention is commonly used for steeply inclined pillars; however, this method suffers from problems such as insufficient production capacity, high costs, low efficiency, high operational risks, low mechanization, and high labor intensity for workers. Furthermore, the presence of caving debris on the right side of the pillar poses a serious threat to worker safety during mining. Additionally, waste rock is easily mixed in, increasing ore dilution. Moreover, blasting disturbances can easily affect the stability of the backfill body on the left side. Therefore, it is urgent to reduce the dynamic disturbance of the backfill body caused by blasting operations and improve mine safety by optimizing blasting parameters. Summary of the Invention

[0003] To address the above problems, the purpose of this invention is to provide a mining method for steeply inclined isolation pillars, which improves mining safety, increases mining efficiency, and reduces the destructive impact of blasting disturbances on the filling area.

[0004] To achieve the above objectives, the present invention provides a mining method for steeply inclined isolation pillars, comprising a preparation process, a cutting process, and a blasting process, characterized in that: the blasting parameters to be determined during the blasting process include micro-delay time;

[0005] The process for determining the differential time is as follows:

[0006] △T=T1+T2+T3+T4+T5 (1)

[0007]

[0008]

[0009]

[0010]

[0011] In equations (1) to (5), ΔT is the differential time; T1 is the initiation system time, 12–16 ms; T2 is the time required for the elastic stress wave to travel to the free surface and return, ms; T3 is the time for the ore body to form a crack, ms; T4 is the time for the fractured ore body to detach from the rock mass, ms; T5 is the time for the empty slot formed after the front row blasting, ms; W is the minimum resistance line, m; c p The velocity of sound waves inside the ore is 3000 m / s; R is the crack length in meters, which can be approximated as R = W; vt V is the crack propagation velocity, 100–150 m / s; S is the crack width, 0.01 m; v s The average velocity of the broken ore body detaching from the rock mass is 4–7 m / s; L is the width of the caving channel, 0.2 m; U is the average impact velocity of the collapsed ore block, 50–100 m / s.

[0012] The process of determining the minimum resistance line W in equations (2) and (3) is as follows:

[0013]

[0014] In equation (6), The borehole diameter is in mm.

[0015] As a preferred embodiment, the blasting adopts a blasting mode that combines medium-deep holes and shallow holes, and the hole layout parameters include the hole bottom distance.

[0016] The process for determining the hole bottom distance is as follows:

[0017] α=mWQ (7)

[0018] In equation (7), α is the hole bottom distance, m; W is the minimum resistance line, m; m is the hole density coefficient, and the value of m ranges from 0.85 to 1.5.

[0019] As a preferred embodiment, the blasting parameters also include segment heights; the segment heights are 10 to 20 meters, and the stage heights are not less than three segment heights.

[0020] As a preferred embodiment, the blasting parameters also include determining the unit explosive consumption:

[0021] The process for determining the unit explosive consumption is as follows:

[0022]

[0023] In equation (8), q is the unit explosive consumption (kg / t); f is the Protodyakonov hardness coefficient of the ore; k is the correction factor; and γ is the ore bulk density (t / m³). 3 .

[0024] As a preferred embodiment, the blasting parameters also include the amount of ore blasted per row of boreholes and the amount of explosive charge per row;

[0025] The process for determining the ore blasting volume for each row of blast holes is as follows:

[0026] Q1=S×W×r (9)

[0027] In formula (9), Q1 is the ore caving volume per row of blast holes; S is the area of ​​the fan-shaped ore caving volume formed by a row of fan-shaped blast holes; m 2 r is the bulk density of the ore, t / m³ 3;

[0028] The process for determining the amount of explosive charge per row is as follows:

[0029] Q2 = Q1 × q (10)

[0030] In formula (10), Q2 is the charge per row of boreholes (kg / t); q is the unit explosive consumption (kg / t).

[0031] As a preferred embodiment, the blasting parameters also include the total length of the boreholes in meters:

[0032]

[0033] In formula (11), L is the total length of the boreholes in meters; B is the charge per meter of borehole, kg / m; K is the average charge coefficient of the fan-shaped boreholes; Q2 is the charge per row of boreholes, kg / t.

[0034] As a preferred embodiment, the mining preparation process is as follows: the mining area is arranged along the strike of the ore body; based on the occurrence of the ore body, the ore body is divided into stages from top to bottom at a certain height; within each stage, several mining sections are divided; within each stage, a drilling roadway is arranged along the strike of the ore body for ore extraction; the ore body is gradually caving down and mining from top to bottom; an access road is arranged in each section of the ore body; within the access road, the ore body is gradually caving down by compression and blasting; and an ore extraction traverse is arranged in the last section of each stage.

[0035] The advantages of this invention are:

[0036] (1) By adopting micro-delay blasting technology and reasonably controlling the micro-delay time between rows and between holes, the first explosive causes certain damage in the ore body, forming a certain width of cracks and additional free surfaces, which provides favorable blasting conditions for the subsequent explosive. By reasonably selecting blasting parameters and changing the direction of the minimum resistance line of the subsequent explosive to make its action direction parallel to the wall, the throwing distance and blasting width of the ore are reduced, the blasting effect is significantly improved and the seismic effect is reduced. While achieving the purpose of crushing the ore, the impact on the left filling area is minimized as much as possible.

[0037] (2) In this embodiment, by controlling the borehole density coefficient, borehole bottom distance, ore caving volume per row of boreholes, charge volume per row, and total borehole length, the ore block size is adjusted to ensure that the ore flow velocity on the left side of the ore body is greater than that on the right side, thereby preventing the premature mixing of broken ore and rock fragments in the upper right side, and achieving simultaneous ore extraction on both sides, thus reducing the ore dilution rate. Attached Figure Description

[0038] Figure 1 This is a cross-sectional view of the ore body of the steeply inclined isolation pillar in this embodiment;

[0039] Figure 2 for Figure 1 Cross-sectional view along the CC line;

[0040] Figure 3 A schematic diagram of the borehole layout;

[0041] Figure 4 Diagram of gun tamping for blast holes;

[0042] The components in the diagram are labeled as follows: 1. Filling material; 2. Marble; 3. Collapsed ore; 4. Isolation pillar; 5. Drilling tunnel; 6. Collapsed ore; 7. Blasting hole; 8. Large chunks of collapsed ore; 9. Medium chunks of collapsed ore; 10. Small chunks of collapsed ore. Detailed Implementation

[0043] To better understand the present invention, the invention will be described in detail below with reference to the accompanying drawings and specific examples.

[0044] Example

[0045] In this embodiment, the steeply inclined isolation pillar is as follows: Figure 1 and Figure 2 As shown, the left side of the isolation pillar 4 is the filling body 1, and above the filling body 1 is marble 2. The right side of the isolation pillar 4 is caving debris 3. The ore body has a dip angle of 60°, a thickness of 15m, a segment height of 20m, and a stage height of 4 segments. The mining method for the steeply inclined isolation pillar in this embodiment includes the following steps:

[0046] (1) Sample preparation process:

[0047] The mining area is arranged along the strike of the ore body. Based on the occurrence of the ore body, the ore body is divided into stages from top to bottom at a certain height. Within each stage, several mining sections are divided. A drilling roadway 5 is arranged along the strike of the ore body within each stage for ore extraction. The ore body is gradually caved down and mined from top to bottom. An access road is arranged in each section of the ore body. The ore body is gradually caved down by compression and blasting within the access road. An ore extraction tunnel is arranged in the last section of each stage.

[0048] (2) Cutting project: Cutting wells are arranged in the ore room along the dip of the ore body.

[0049] (3) Blasting process: Determine blasting parameters, borehole diameter Minimum resistance line W, borehole density coefficient m, borehole bottom distance a, unit explosive consumption q, ore blasting amount per row of boreholes Q1, explosive charge per row Q2, total borehole length in meters L, and detonation differential time △T;

[0050] (3.1) Determine the borehole diameter

[0051] Based on the actual conditions of the ore and rock, in order to facilitate control of the size of the crushed ore, improve blasting quality, fully utilize the drilling capacity of the rock drilling equipment, increase drilling speed, and control blasting costs, the borehole diameter is selected as follows:

[0052] (3.2) Determine the minimum resistance line W:

[0053] Determined based on borehole diameter and ore / rock properties.

[0054]

[0055] (3.3) Determine the borehole density coefficient m and the borehole bottom distance a

[0056] The borehole density coefficient is the ratio of the distance between the bottom of the boreholes to the minimum resistance line. The optimal value is 0.95 to 1.2, and the reasonable range is 0.85 to 1.5.

[0057] α=mWQ (7)

[0058] Combination Figure 3 and Figure 4 As shown, this embodiment improves the blasting effect by combining shallow and medium-deep hole blasting modes based on the reasonable selection of hole spacing (hole opening distance and hole bottom distance). If the hole mesh is too sparse, it will increase the proportion of large blocks, while if the hole mesh is too dense, it will waste blasting materials and reduce the amount of ore blasted per meter.

[0059] (3.4) The unit explosive consumption q is determined as:

[0060]

[0061] In the formula, q is the unit explosive consumption (kg / t); f is the Protodyakonov hardness coefficient of the ore; k is the correction factor; and γ is the ore bulk density (t / m³). 3 .

[0062] The specific range of unit explosive consumption should be determined based on the actual situation. It is necessary to consider not only whether all the ore can be broken down, but also to control the size of the broken ore to reduce the mixing of waste rock from the upper plate.

[0063] (3.5) The process for determining the ore blasting volume Q1 for each row of blast holes is as follows:

[0064] Q1=S×W×r (9)

[0065] In the formula, Q1 is the ore caving volume per row of blast holes; S is the area of ​​the fan-shaped ore caving volume formed by a row of fan-shaped blast holes; m 2 r is the bulk density of the ore, t / m³ 3 ;

[0066] (3.6) The process for determining the amount of explosive per row, Q2, is as follows:

[0067] Q2 = Q1 × q (10)

[0068] In the formula, Q2 is the charge per row of boreholes (kg / t); q is the unit explosive consumption (kg / t).

[0069] (3.7) Total length of boreholes in meters:

[0070]

[0071] In the formula, L is the total length of the boreholes in meters; B is the charge per meter of borehole (kg / m); K is the average charge coefficient for the fan-shaped boreholes; and Q2 is the charge per row of boreholes (kg / t).

[0072] Combination Figure 3 As shown, this embodiment adjusts the ore block size by controlling the borehole density coefficient m, borehole bottom distance a, ore blasting volume per row of boreholes, charge volume per row, and total borehole length, to ensure that the ore flow velocity on the left side of the ore body is greater than that on the right side. Specifically, the ore blasting in the ore body is distributed from left to right as small ore blocks 8, medium ore blocks 9, and large ore blocks 10. This embodiment comprehensively adjusts the ore block size by controlling the borehole density coefficient m, borehole bottom distance a, ore blasting volume per row of boreholes, charge volume per row, and total borehole length, to ensure that the ore flow velocity on the left side of the ore body is greater than that on the right side, preventing the premature mixing of broken ore and rock fragments in the upper right, and achieving simultaneous ore extraction on both sides, thus reducing the ore dilution rate.

[0073] Combination Figure 4 As shown, the diagram for charging and packing the blast hole is as follows: Figure 4 As shown, selecting a reasonable plugging length at the orifice avoids excessive ore powder generation during blasting due to overly dense blast holes at the orifice, thereby improving ore quality, reducing dust pollution, and improving the construction environment.

[0074] (3.8) Detonation method

[0075] The overall detonation sequence adopts the method of detonating sequentially from the bottom of the hole to the opening, and from the left blast hole to the right blast hole. The micro-delay time is determined by comprehensively considering factors such as the influencing factors of the underground detonation system, the development speed of the blasting fissures, and the full utilization of the existence time of the empty slots formed by the front row of blasting to increase the collision effect of the ore falling from the rear row of blasting holes on the ore falling from the front row.

[0076] The overall differential time is determined by the combined differential differences between rows and between holes. The process for determining the differential time is as follows:

[0077] △T=T1+T2+T3+T4+T5 (1)

[0078]

[0079]

[0080]

[0081]

[0082] In the formula, T1 is the detonation system time, which is 12 to 16 ms;

[0083] T2 is the time, in milliseconds, required for the elastic stress wave to travel to the free surface and return.

[0084] T3 is the time it takes for cracks to form in the ore body, in milliseconds;

[0085] T4 is the time it takes for the fractured ore body to separate from the rock mass, in milliseconds;

[0086] T5 is the time, in milliseconds, for the empty slot formed after the front row explosion.

[0087] W is the line of minimum resistance, m; c p The velocity of sound waves inside the ore is 3000 m / s; R is the crack length in meters, which can be approximated as R = W; v t V is the crack propagation velocity, 100–150 m / s; S is the crack width, 0.01 m; v s The average velocity of the broken ore body detaching from the rock mass is 4–7 m / s; L is the width of the caving channel, 0.2 m; U is the average impact velocity of the collapsed ore block, 50–100 m / s.

[0088] In this embodiment, the actual rock conditions are as follows: the iron ore is hard rock, and the diameter of the boreholes taken earlier is... The minimum resistance line W is calculated to be 1.52-1.9m. Here, we take W = 1.8m and substitute it into the formula to calculate ΔT = 30.6-45.7ms.

[0089] Furthermore, in practical engineering, optimization is usually required through experiments and field tests to obtain the optimal blasting time difference. Micro-delay blasting time control is mainly achieved by precisely controlling the detonation velocity and quantity of the explosives, which can be remotely controlled via a microcomputer.

[0090] a) Select appropriate explosives: Select explosives with appropriate detonation speed and power based on engineering requirements and geological conditions;

[0091] b) Accurate measurement according to the blasting plan: Use measuring instruments (such as total station, rangefinder, etc.) to accurately measure the blasting area to ensure that the position and depth of the blasting holes meet the design requirements;

[0092] c) Install sensors: Install sensors in the explosive to monitor various parameters (such as pressure, vibration, etc.) in real time during the explosion process.

[0093] d) Write control programs: Based on the predetermined blasting time and sequence, write control programs to control the detonation sequence and time of explosives.

[0094] e) Implementation of blasting: Detonation is carried out according to the control procedure, and the blasting process is monitored in real time by sensors.

[0095] f) Data Analysis: Collect sensor data and analyze whether the actual blasting time and sequence meet expectations. If there are deviations, adjust the control program and conduct the next test.

[0096] g) Optimization and adjustment: Based on the test results, continuously optimize the blasting scheme and control program to achieve precise control of the micro-delay blasting time.

[0097] Fan-shaped blasting using micro-delay blasting technology can significantly improve blasting effects and reduce disturbance effects. Bottom-initiation is superior to orifice-initiation. Orifice-initiation results in earlier high-stress states near the orifice, leading to greater ore displacement, but the total energy is lower, which is detrimental to ore crushing. Millisecond blasting, with a well-chosen time difference, weakens the mutual interference of shock waves generated by the blasts, reducing the vibration effect on the left-side filling area and promoting the stability of the filling body. Furthermore, due to the extremely short interval between adjacent explosives, the stress wave generated by the first explosive in the ore body has not yet dissipated before the second explosive detonates. This subjects the blasted ore body to bidirectional stress, thereby improving crushing effects, reducing explosive usage, and lowering economic costs.

[0098] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A mining method for a steeply inclined isolation pillar, comprising a preparation process, a cutting process, and a blasting process, characterized in that: The blasting parameters that need to be determined during the blasting process include the micro-delay time; The process for determining the differential time is as follows: （1） （2） （3） （4） （5） In equations (1) to (5), ΔT is the differential time; T 1 represents the detonation system time, ranging from 12 to 16 ms; T 2 represents the time required for the elastic stress wave to propagate to the free surface and return, in milliseconds; T 3 represents the time it takes for cracks to form in the ore body, in milliseconds; T 4 represents the time it takes for the fractured ore body to separate from the rock mass, in milliseconds; T 5 represents the time, in milliseconds, for the empty slot formed after the front row explosion. W The minimum resistance line is m; c p The velocity of sound waves inside the ore is 3000 m / s; R Let the crack length be m, approximately taken as... R = W ; v t The crack propagation rate is 100~150 m / s; S The crack width is 0.01m; v s The average velocity of the broken ore body separating from the rock mass is 4~7 m / s; L The width of the empty slot is 0.2m; U The average impact velocity of the collapsing ore block is 50~100m / s; The minimum resistance line in equations (2) and (3) W The process of determining is as follows: （6） In equation (6), The borehole diameter is in mm.

2. The mining method for steeply inclined isolation pillars according to claim 1, characterized in that, The blasting adopts a blasting mode that combines medium-deep holes and shallow holes, and the hole layout parameters include the hole bottom distance. The process for determining the hole bottom distance is as follows: （7） In equation (7), α is the distance from the bottom of the hole, in meters; W denoted as the minimum resistance line, m; m is the borehole density coefficient, with a value ranging from 0.85 to 1.

5.

3. The mining method for steeply inclined isolation pillars according to claim 1, characterized in that, The blasting parameters also include segment heights; the segment heights are 10-20m, and the stage height is not less than 3 segment heights.

4. The mining method for steeply inclined isolation pillars according to claim 1, characterized in that, The blasting parameters also include determining the unit explosive consumption: The process for determining the unit explosive consumption is as follows: （8） In equation (8), q represents the unit explosive consumption, kg / t; The Protodextrin hardness coefficient of the ore; This is a correction factor; The bulk density of the ore, t / m³ 3 .

5. The mining method for steeply inclined isolation pillars according to claim 4, characterized in that, The blasting parameters also include the amount of ore blasted per row of boreholes and the amount of explosives per row; The process for determining the ore blasting volume for each row of blast holes is as follows: （9） In formula (9), Q1 is the ore caving volume per row of blast holes; S is the area of ​​the fan-shaped ore caving volume formed by a row of fan-shaped blast holes; m 2 r is the bulk density of the ore, t / m³ 3 ; The process for determining the amount of explosive charge per row is as follows: （10） In formula (10), Q2 is the charge per row of boreholes (kg / t); q is the unit explosive consumption (kg / t).

6. The mining method for steeply inclined isolation pillars according to claim 5, characterized in that, The blasting parameters also include the total length of the blast holes in meters: （11） In formula (11), L is the total length of the boreholes in meters; B is the charge per meter of borehole, kg / m; K is the average charge coefficient of the fan-shaped boreholes; Q2 is the charge per row of boreholes, kg / t.

7. The mining method for steeply inclined isolation pillars according to claim 1, characterized in that, The mining preparation process is as follows: the mining area is arranged along the strike of the ore body. Based on the occurrence of the ore body, the ore body is divided into stages from top to bottom at a certain height. Several mining sections are divided within each stage. A drilling roadway is arranged along the strike of the ore body within each stage for ore extraction. The ore body is gradually caving down and mining from top to bottom. An access road is arranged in each section of the ore body. The ore body is gradually caving down by compression and blasting within the access road. An ore extraction tunnel is arranged in the last section of each stage.

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