Method for determining pre-splitting blasting parameters of saturated ore rock of surface mine

Abstract

The invention discloses a method for determining pre-splitting blasting parameters of saturated ore rock of a surface mine, and relates to the technical field of blasting, the method comprises the following steps: carrying out rock core sampling on each blast hole of a blasted rock mass, and determining a saturated rock mass part and a non-saturated rock mass part of the rock mass corresponding to each blast hole according to a rock core sampling result; the filling medium of the saturated rock mass part of each blast hole is water; for each blast hole, when the length of the saturated rock mass part is larger than the first set length, the interval between the lowest charging section and the bottom of the blast hole is set to be a second set length, and the linear charging density is determined according to the length of the saturated rock mass part; and the first set length is the sum of the lowest charging section and the second set length. The blasting efficiency can be improved, and meanwhile explosive unit consumption is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of blasting, and particularly to a method for determining pre-splitting blasting parameters of water-saturated ore rock in open-pit mines. Background Art

[0002] In recent years, with the increasing depth of mineral resource excavation in open-pit mines, the geological conditions of deep ore rock construction have gradually changed. In some mines with special geological conditions, the underground water inflow is large, and the rock mass has been soaked by groundwater for a long time, with a high content of free water inside and even in a water-saturated state. As a common mineral resource in mines, water has a great impact on the blasting performance of ore rock. It not only changes the mechanical properties and deformation characteristics of the rock mass, but also affects its blasting characteristics. In open-pit mine blasting, the blasting effects in water-rich blasting areas are uneven, and the problems of large bottom residue rate and high explosive specific consumption are common. Therefore, studying the blasting performance of water-saturated ore rock has important engineering significance.

[0003] During the process of mine exploitation, pre-splitting blasting is the main means to reduce the impact of vibration on the slope, and it directly affects the shaping effect and stability of the mine slope. Traditional methods for designing blasting hole patterns usually rely on empirical formulas or numerical simulations. When conducting blasting design, the mechanical properties, integrity coefficient, fracture characteristics, etc. of the rock are mostly considered, but the influence of the water content state is often ignored. The physical and mechanical properties of ore rock will change greatly in the water-saturated state, affecting the propagation of blasting stress waves, the expansion of cracks, and the distribution of blasting fragment sizes, resulting in problems such as poor pre-splitting blasting effect, high explosive specific consumption, and large blasting vibration. Summary of the Invention

[0004] The purpose of the present application is to provide a method for determining pre-splitting blasting parameters of water-saturated ore rock in open-pit mines, which can improve the blasting efficiency and reduce the explosive specific consumption at the same time.

[0005] To achieve the above purpose, the present application provides the following solution:

[0006] The present application provides a method for determining pre-splitting blasting parameters of water-saturated ore rock in open-pit mines, and the method for determining pre-splitting blasting parameters of water-saturated ore rock in open-pit mines includes:

[0007] Taking core samples from each blast hole of the rock mass to be blasted, and determining the water-saturated rock mass part and non-water-saturated rock mass part of the rock mass corresponding to each blast hole according to the core sampling results; the filling medium of the water-saturated rock mass part of each blast hole is water;

[0008] For each blast hole, when the length of the water-saturated rock mass part is greater than the first set length, set the lowest charging section to be spaced from the bottom of the blast hole by a second set length, and determine the linear charge density according to the length of the water-saturated rock mass part; the first set length is the sum of the lowest charging section and the second set length.

[0009] Optionally, the linear charge density is determined according to the length of the water-saturated rock mass part, specifically including:

[0010] When the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the linear charge density of the water-saturated rock mass part is calculated according to the formula q w = 0.8q;

[0011] where q w is the optimized linear charge density; q is the linear charge density of the non-water-saturated rock mass part.

[0012] Optionally, the linear charge density is determined according to the length of the water-saturated rock mass part, and specifically further includes:

[0013] When the rock mass corresponding to the blast hole is partially water-saturated rock mass, the linear charge density of the water-saturated rock mass part is calculated according to the formula ;

[0014] where q w is the optimized linear charge density; l1 is the blast hole depth; l2 is the length of the water-saturated rock mass part in the blast hole; q is the linear charge density of the non-water-saturated rock mass part.

[0015] Optionally, for each blast hole, when the length of the water-saturated rock mass part is greater than the first set length, the lowest charging section is set at a second set length from the bottom of the blast hole. After determining the linear charge density according to the length of the water-saturated rock mass part, the method for determining the pre-splitting blasting parameters of the water-saturated ore and rock in the open-pit mine further includes:

[0016] When the rock mass to be blasted is entirely water-saturated rock mass, each blast hole is detonated one by one in a preset order;

[0017] When the rock mass to be blasted has partially water-saturated rock mass, the blast holes are grouped and detonated one by one in a preset grouping order, and multiple blast holes in each group are detonated at the same time.

[0018] Optionally, when the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the charging sections in the blast hole from low to high are successively the continuous enhanced charging section, the enhanced section, and the normal section. The continuous enhanced charging section is spaced from the bottom of the blast hole by the second set length. The continuous enhanced charging section is 2 to 3 cartridge lengths and there is no interval between cartridges. The interval between the continuous enhanced charging section and the enhanced section is 0.8 m to 1.2 m, and the sum of the interval between the continuous enhanced charging section and the enhanced section and the enhanced section is 7.0 m to 9.0 m; the interval between the enhanced section and the normal section is 0.8 m to 1.2 m, and the sum of the interval between the enhanced section and the normal section and the normal section is 2.0 m to 3.0 m.

[0019] Optionally, when the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the length of the continuous enhanced charging section is twice the length of the enhanced section.

[0020] Optionally, when the rock mass corresponding to the blast hole is completely water-saturated, the lengths of the strengthening section and the normal section are the same, the number of the middle explosive cartridges in the strengthening section is twice that of the normal section, and the strengthening section is 1 to 2 explosive cartridge lengths.

[0021] Optionally, the value range of the second set length is 1 m to 2 m.

[0022] Optionally, the value of the second set length is 1.5 m.

[0023] Optionally, the rock mass to be blasted is a metal mine, a non-metal mine or a coal mine.

[0024] According to the specific embodiments provided by the present application, the following technical effects are disclosed:

[0025] The present application provides a method for determining pre-splitting blasting parameters of water-saturated ore rock in an open-pit mine, which determines the water-saturated rock mass part and the non-water-saturated rock mass part of the rock mass corresponding to each blast hole, optimizes the charging structure of the water-saturated rock mass part. When the length of the water-saturated rock mass part is greater than the first set length, a second set length is set between the lowest charging section and the bottom of the blast hole, and the ultra-high pressure water jet generated after blasting is used to break the rock mass at the bottom, generating obliquely downward blasting cracks, reducing the generation of bench toes, thereby improving the blasting efficiency. The linear charge density is optimized according to the length of the water-saturated rock mass part, and the unit consumption of explosives is reduced. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a schematic flow chart of a method for determining pre-splitting blasting parameters of water-saturated ore rock in an open-pit mine provided by an embodiment of the present application.

[0028] Figure 2 It is a schematic diagram of the water content state and the charging structure provided by an embodiment of the present application.

[0029] Figure 3 It is a schematic diagram of the blasting effect after the non-water interval blast holes.

[0030] Figure 4 It is a schematic diagram of the blasting effect after the water interval blast holes.

[0031] Figure 5 It is a schematic diagram of hole-by-hole initiation provided by an embodiment of the present application.

[0032] Figure 6 Schematic diagram of grouped delay initiation provided for an embodiment of the present application.

[0033] Figure 7 Schematic diagram of a charge structure provided for an embodiment of the present application. Detailed implementation manners

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.

[0035] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0036] In an exemplary embodiment, the present application provides a method for determining pre-splitting blasting parameters of water-saturated ore rock in an open-pit mine, as Figure 1 shown. The method for determining pre-splitting blasting parameters of water-saturated ore rock in an open-pit mine includes Step 101 - Step 102.

[0037] Step 101: Take core samples from each blast hole of the rock mass to be blasted, and determine the water-saturated rock mass part and non-water-saturated rock mass part of the rock mass corresponding to each blast hole according to the core sampling results; the filling medium of the water-saturated rock mass part of each blast hole is water.

[0038] Step 102: For each blast hole, when the length of the water-saturated rock mass part is greater than a first set length, set the lowest charging section to be spaced from the bottom of the blast hole by a second set length, and determine the linear charge density according to the length of the water-saturated rock mass part; the first set length is the sum of the lowest charging section and the second set length.

[0039] The blast holes in Step 101 - Step 102 refer to pre-splitting holes.

[0040] The lowest charging section is a continuously strengthened charging section. When the height of the water-saturated rock mass around the blast hole satisfies the first set length and can completely submerge the continuously strengthened charging section, a water interval section is set at the bottom of the blast hole, and the length of the water interval section is the second set length.

[0041] The method for determining pre-splitting blasting parameters of water-saturated ore rock in an open-pit mine according to the present application can optimize the design of the pre-splitting blasting charge structure and the initiation method according to the ore rock characteristics under different water content states, effectively improve the blasting efficiency, improve the blasting effect, and achieve the effect of protecting the slope stability.

[0042] In this application, the mined area to be blasted is divided into two types: water-saturated rock mass and non-water-saturated rock mass. The mechanical properties of the water-saturated rock mass change, and its blasting performance is relatively reduced compared to the non-water-saturated rock mass. However, due to the effect of the filling medium water on the transmission of stress waves, when the filling medium is water, the charging structure can be optimized.

[0043] The water content state and the charging structure are as Figure 2 shown. The water content state can be detected by measuring the water content. Core samples are taken using drilling equipment. When the water content of the core samples obtained on-site reaches 90% or more of the natural saturation water content, it is considered to reach the water-saturated state and is a water-saturated rock mass. Otherwise, it is a non-water-saturated rock mass. Before optimizing the charging structure, the water level in the hole should be checked to determine which of the following optimization methods to use.

[0044] In an exemplary embodiment, as Figure 2 shown in (a) of, when the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the charging sections in the blast hole from low to high are successively the continuous enhanced charging section, the enhanced section, and the normal section. The continuous enhanced charging section is spaced from the bottom of the blast hole by a second set length a. The continuous enhanced charging section b is 2 to 3 cartridge lengths and there is no interval between the cartridges, with continuous charging. The interval c between the continuous enhanced charging section and the enhanced section ranges from 0.8 m to 1.2 m, and the sum d of the interval between the continuous enhanced charging section and the enhanced section and the enhanced section ranges from 7.0 m to 9.0 m; the interval e between the enhanced section and the normal section ranges from 0.8 m to 1.2 m, and the sum f of the interval between the enhanced section and the normal section and the normal section ranges from 2.0 m to 3.0 m. There is also a stemming section above f, and the stemming length is g, where g ranges from 2.0 m to 3.0 m.

[0045] Figure 2 In the blast hole, there is more than one cartridge, Figure 2 In, for the convenience of display, only one section of some cartridges is drawn, and the actual number of sections should be determined according to the on-site situation.

[0046] When the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the length of the continuous enhanced charging section is twice the length of the enhanced section.

[0047] When the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the lengths of the enhanced section and the normal section are the same. The number of cartridges in the enhanced section is twice that of the normal section, and the enhanced section is 1 to 2 cartridge lengths.

[0048] In an exemplary embodiment, the value range of the second set length is 1 m to 2 m.

[0049] In an exemplary embodiment, the value of the second set length is 1.5 m.

[0050] The traditional charging structure is asFigure 3 As shown, the explosive is detonated at the bottom of the blast hole. After blasting, the cracks expand horizontally or vertically, and a certain height of bottom residue is likely to form at the bottom. When the water content state and the water level in the blast hole are Figure 2 as shown in (a) in the figure, a water interval section with a length of a can be reserved at the bottom. The ultra-high-pressure water jet generated after blasting is used to break the rock mass at the bottom. As Figure 4 shown, obliquely downward blasting cracks are generated, reducing the generation of bottom residue.

[0051] In an exemplary embodiment, the linear charge density is determined according to the length of the water-saturated rock mass part, specifically including: As Figure 2 shown in (a) in the figure, when the rock mass corresponding to the blast hole is entirely water-saturated rock mass, according to the formula q w = 0.8q to calculate the linear charge density of the water-saturated rock mass part.

[0052] Among them, q w is the optimized linear charge density, kg / m; q is the linear charge density of the non-water-saturated rock mass part, that is, the original linear charge density, the linear charge density without considering the water content state, kg / m.

[0053] Regarding the influence of the Stefan effect and the meniscus effect, the blasting effect of water-saturated rock mass should be worse than that of normal rock mass. However, due to the incompressible nature of water, in the decoupled charge structure, when the stress propagates to the rock mass after the explosion of the explosive, there is a stronger stress peak, and the blasting effect is better than that when air is the medium. Therefore, the amount of explosive used in water-saturated rock mass should be reduced. The Stefan effect, also known as the Stefan-Boltzmann law, is an important law in thermodynamics.

[0054] Determining the linear charge density according to the length of the water-saturated rock mass part specifically further includes: As Figure 2 shown in (b) and (c) in the figure, when the rock mass corresponding to the blast hole is partially water-saturated rock mass, according to the formula to calculate the linear charge density of the water-saturated rock mass part. Two different linear charge densities are used respectively below and above the water level.

[0055] Among them, q w is the optimized linear charge density, kg / m; l1 is the blast hole depth, m; l2 is the length of the water-saturated rock mass part in the blast hole, m; q is the original linear charge density, kg / m.

[0056] When the length of the water-saturated rock mass part is less than or equal to the first set length, as Figure 2 shown in (d) in the figure, the charge structure is not optimized.

[0057] The water-saturated rock mass area is designed according to the charge structure proposed in this application, while the non-water-saturated rock mass area is designed according to the original charge structure.

[0058] Traditional presplitting blasting is carried out by the simultaneous initiation of presplitting holes (blastholes). However, when blasting saturated rock masses, there is a large amount of water in the holes, and there is a lack of air to buffer the explosive gases and the impact pressure of the explosion stress wave. Therefore, the vibration generated on the rock mass is relatively larger. In this case, the method of delay initiation needs to be adopted to reduce the blasting vibration.

[0059] In an exemplary embodiment, for each blasthole, when the length of the saturated rock mass part is greater than a first set length, a lowest charging section is set at a second set length from the bottom of the blasthole, and after determining the linear charge density according to the length of the saturated rock mass part, the method for determining the presplitting blasting parameters of the saturated ore rock in the open-pit mine further includes:

[0060] When the rock mass to be blasted is entirely saturated rock mass and the water level in the blasthole is higher than the submerged explosive, each blasthole is initiated one by one in a preset order. As Figure 5 shown, the initiation time of the first hole is t1, and in sequence, the nth group is t n . This application mainly determines the presplitting blasting parameters of the presplitting area, and the specific delay time of the presplitting area is consistent with the delay interval between holes in the main blasting area.

[0061] When the rock mass to be blasted has some saturated rock mass, the blastholes are grouped and initiated one by one in a preset grouping order, and multiple blastholes in each group are initiated simultaneously. As Figure 6 shown, the water level in the blasthole does not completely submerge the explosive, and the presplitting holes can be initiated simultaneously in groups of 4 holes or multiple holes. The initiation time of the first group is t1, and in sequence, the nth group is t n . The specific delay time is consistent with the delay interval between holes in the main blasting area.

[0062] In an exemplary embodiment, taking the presplitting blasting of an open-pit metal mine with a Proctor coefficient f′ = 10 - 12, a hole depth of 15 m, and a hole diameter of 150 mm as an example, when the hole spacing is 1.6 - 1.8 m, the original linear charge density is 1.2 kg / m, the total charge is 18 kg, the detonating cords are connected in series and initiated simultaneously, without delay setting, and the cartridge is of size and the cartridge mass is 0.3 kg. When the rock mass to be blasted is in a saturated state, the design and optimization of the presplitting blasting parameters are as follows:

[0063] q w = 0.8q = 0.8 × 1.2 = 0.96 kg / m;

[0064] The total charge Q = q w × 15 = 14.4 kg;

[0065] Among them, the specific charging structure is as Figure 7As shown in the figure, a is taken as 1.5 m; b is twice the charging length of the enhanced section, taking the length of 3 cartridges, with a length of 1 m and continuous charging. The value of c is taken between 0.8 and 1.2 m, and here it is taken as 1.0 m; d is the length of the enhanced section, which is taken as 8.0 m here; e is the interval distance between the normal section and the enhanced section, and here it is taken as 1.0 m; f is the normal length, which is taken as 2 m; g is the stemming length, which is taken as 2.5 m. Hole-by-hole initiation is adopted, and the delay time between holes is the same as that between holes in the main blasting area, which is 24 ms. Initiation is carried out before the main blasting area.

[0066] In an exemplary embodiment, the rock mass to be blasted is a metal mine, a non-metal mine or a coal mine. This application can be widely applied to blasting projects in various mines such as metal mines, non-metal mines, and coal mines, and has important popularization and application value.

[0067] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0068] In this article, specific examples are used to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A method for determining pre-splitting blasting parameters of water-saturated ore and rock in open-pit mines, characterized in that, The method for determining the presplitting blasting parameters of water-saturated ore rock in an open-pit mine includes: Taking core samples from each blast hole of the rock mass to be blasted, and determining the water-saturated rock mass part and the non-water-saturated rock mass part of the rock mass corresponding to each blast hole according to the core sampling results; the filling medium of the water-saturated rock mass part of each blast hole is water. For each blast hole, when the length of the water-saturated rock mass part is greater than the first set length, set the lowest charging section to be spaced from the bottom of the blast hole by a second set length, and determine the linear charge density according to the length of the water-saturated rock mass part; the first set length is the sum of the lowest charging section and the second set length.

2. The method for determining the pre-splitting blasting parameters of water-saturated ore and rock in open-pit mines according to claim 1, characterized in that Determining the linear charge density according to the length of the water-saturated rock mass part specifically includes: When all the rock masses corresponding to the blast holes are saturated rock masses, the linear charge density of the saturated rock mass part is calculated according to the formula q w = 0.8q; Among them, q w is the optimized linear charge density; q is the linear charge density of the unsaturated rock mass part.

3. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 1, characterized in that, Determining the linear charge density according to the length of the water-saturated rock mass part also specifically includes: When the rock mass corresponding to the blast hole is a partially saturated rock mass, according to the formula calculate the linear charge density of the saturated part of the rock mass; where q w is the optimized linear charge density; l1 is the hole depth; l2 is the length of the water-saturated rock mass part in the hole; q is the linear charge density of the non-water-saturated rock mass part.

4. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 1, characterized in that, For each blast hole, when the length of the water-saturated rock mass part is greater than the first set length, set the lowest charging section to be spaced from the bottom of the blast hole by a second set length, and after determining the linear charge density according to the length of the water-saturated rock mass part, the method for determining the presplitting blasting parameters of water-saturated ore rock in an open-pit mine further includes: When the entire rock mass to be blasted is water-saturated rock mass, detonating each blast hole one by one in a preset order. When the rock mass to be blasted has some water-saturated rock mass, grouping the blast holes and detonating them one by one in a preset grouping order, and multiple blast holes in each group are detonated at the same time.

5. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 1, characterized in that, When the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the charging sections in the blast hole from low to high are successively a continuous enhanced charging section, an enhanced section, and a normal section. The continuous enhanced charging section is spaced from the bottom of the blast hole by a second set length. The continuous enhanced charging section is 2 to 3 cartridge lengths and there is no interval between the cartridges. The interval between the continuous enhanced charging section and the enhanced section is 0.8 m to 1.2 m, and the sum of the interval between the continuous enhanced charging section and the enhanced section and the enhanced section is 7.0 m to 9.0 m; the interval between the enhanced section and the normal section is 0.8 m to 1.2 m, and the sum of the interval between the enhanced section and the normal section and the normal section is 2.0 m to 3.0 m.

6. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 5, characterized in that, When the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the length of the continuous enhanced charging section is twice the length of the enhanced section.

7. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 5 or 6, characterized in that, When the rock mass corresponding to the blast hole is entirely water-saturated rock mass, the lengths of the enhanced section and the normal section are the same. The number of cartridges in the enhanced section is twice that of the normal section, and the enhanced section is 1 to 2 cartridge lengths.

8. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 1, characterized in that The value range of the second set length is 1 m to 2 m.

9. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 1, wherein The value of the second set length is 1.5 m.

10. The method for determining pre-splitting blasting parameters of saturated ore and rock in open-pit mines according to claim 1, characterized in that, The rock mass to be blasted is a metal mine, a non-metal mine or a coal mine.

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