Blast preparation method and blast method

Abstract

To provide a blast preparation method that can sufficiently reduce the time required for blast preparation and efficiently utilize the energy generated by the explosion for crushing.SOLUTION: A blast preparation method comprises a loading step of loading a primer 22 and a stick 24 on top of a detonator 20 installed at a bottom of a blast hole 10, and then loading a stemming 28 into the blast hole 10, and in the loading step, a bag body filled with at least a portion of the stemming 28 is fixed within the blast hole 10 at a distance from the stick 24, and an area 26 containing at least one of air and water is provided between the stick and the bag body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One aspect of the present invention relates to a blasting preparation method and a blasting method.

Background Art

[0002] Generally, blasting means a process of crushing rock masses, etc. in addition to cutting out raw stones in mines or quarries, and also in tunnel construction, demolition work of concrete structures, road construction work, etc. Recently, blasting is being carried out not only in remote areas but also in urban areas, such as in underground excavation work of buildings, power line and pipeline work, and subway work. As explosives used for blasting, ammonium nitrate fuel oil explosive (ANFO) and bulk emulsion explosive are known (see, for example, Patent Document 1).

[0003] Blasting varies from small-scale ones that blast single rocks to large-scale ones that blast rock masses of tens of thousands of tons, and methods suitable for the target objects are used. As methods for blasting rock masses, there are common blasting methods (single charge blasting) in which blast holes are drilled in the rock mass and explosives and stemming are loaded inside the blast holes for blasting, methods (deck charge blasting) in which explosives and stemming are arranged alternately for blasting to reduce vibration, methods (air deck blasting) in which a void is provided between the explosives and the stemming for blasting, etc. are known (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In mines where blasting is carried out, water may flow into the blast holes due to the occurrence of groundwater. When there is a possibility of water inflow, it is considered preferable to use a bulk emulsion explosive such as that described in Patent Document 1 as the explosive. However, in the case of a bulk emulsion explosive, foaming occurs after the foaming agent is mixed on site. For this reason, the explosive cannot be immediately covered with stemming. In the case of air deck blasting that forms an air gap by providing a plug as in Patent Document 2, it becomes possible to load the stemming without waiting for the blasting to end, and it is considered that the working time for blast preparation can be shortened to some extent. However, since an operation for fixing the plug in the blast hole is separately required, it has been difficult to sufficiently shorten the working time.

[0006] Therefore, the present invention provides a blast preparation method and a blasting method capable of sufficiently shortening the working time for blast preparation and efficiently using the energy generated by the explosion for crushing.

Means for Solving the Problems

[0007] One aspect of the present invention is a blasting method having a loading step of loading stemming into the blast hole after loading a primer die and an booster die on top of a detonator installed at the bottom of the blast hole, wherein in the loading step, a bag body filled with at least a part of the stemming is fixed in the blast hole at an interval from the booster die, and a region containing at least one of air and water is provided between the booster die and the bag body, thereby providing a blast preparation method. To provide.

[0008] In the above blast preparation method, a bag body filled with at least a part of the stemming is fixed at an interval from the booster die. Such a bag body can be smoothly fixed in the blast hole. Therefore, the working time for blast preparation can be sufficiently shortened. In addition, by fixing the bag body at an interval from the booster die in the blast hole, the energy of the explosion is efficiently used for crushing, and back break can be sufficiently suppressed while granulating the crushed material.

[0009] One aspect of the present invention provides a blasting method having a blasting step of performing blasting at the blasting hole after the above-described blasting preparation method. Since this blasting method includes the above-described blasting preparation method, the working time for preparing for blasting can be sufficiently shortened. In addition, back break can be sufficiently suppressed while granulating the crushed material.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a blasting preparation method and a blasting method capable of sufficiently shortening the working time for preparing for blasting and efficiently using the energy generated by the explosion for crushing.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. However, the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant descriptions may be omitted as appropriate. In addition, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the respective elements are not limited to the ratios shown in the drawings.

[0013] The blasting preparation method according to one embodiment includes a step of forming a blasting hole, a step of installing a detonator at the bottom of the blasting hole and then loading the parent die and the booster die in this order, and a step of loading the charge into the blasting hole. The blasting method according to one embodiment includes a blasting step of performing blasting in the blasting hole after the above blasting preparation method. Hereinafter, the contents common to the embodiments of the blasting preparation method and the blasting method will be described. The blasting preparation method and the blasting method may be performed, for example, for mining ore in a mine, or may be performed in various construction works such as tunnel construction, underground excavation work, or subway construction. In the step of forming the blasting hole, the blasting hole can be formed using a heavy machine such as a drilling machine.

[0014] In the example of FIG. 1, the blasting hole 10 is formed in the rock mass 40. The rock mass 40 may be a rock mass in a mine (for example, a limestone mine). In this example, the blasting hole 10 is slightly inclined with respect to the vertical direction, but is not limited thereto. For example, the blasting hole 10 may extend in the vertical direction or may extend in the horizontal direction. A plurality of blasting holes 10 may be arranged along the face 41 of the rock mass 40. The drilling diameter (inner diameter) of the blasting hole 10 may be 70 to 150 mm, or may be 80 to 130 mm. The resistance R may be 2 to 6 m, or may be 3 to 5 m. The ratio of the resistance R to the drilling diameter may be 30 to 60. The interval (hole spacing) between adjacent blasting holes 10 may be 2 to 8 m, or may be 3 to 6 m. The ratio of the hole spacing to the resistance R may be 0.5 to 4, or may be 1 to 2.

[0015] After forming the blasting hole 10, the detonator 20 is introduced from the opening 12 of the blasting hole 10, and the detonator 20 is installed on the bottom surface of the blasting hole 10. As the detonator 20, for example, an electric detonator, a non-electric detonator, an electronic detonator, etc. can be used. The leg wires (not shown) of the detonator 20 may be connected to the blaster 30 arranged outside the blasting hole 10. Next, the primer 22 is introduced from the opening 12 and loaded into the inside of the blasting hole 10. The primer 22 is what is called booster explosive or priming dynamite and has a function of sufficiently detonating the main charge 24. Examples of the primer 22 include a cast booster, dynamite, and water-containing explosive. Among these, from the viewpoint of enabling smooth blasting even when groundwater flows into the blasting hole, it is preferably a cast booster or a water-containing explosive.

[0016] Next, the main charge 24 is introduced from the opening 12 of the blasting hole 10 and loaded into the inside of the blasting hole 10. Examples of the main charge 24 (body explosive) include ammonium nitrate fuel oil explosive (ANFO) and water-containing explosive (bulk emulsion explosive). Among these, from the viewpoint of enabling smooth blasting even when groundwater flows into the blasting hole, the main charge 24 is preferably a water-containing explosive, more preferably a bulk emulsion explosive.

[0017] The bulk emulsion explosive is loaded into the inside of the blasting hole 10 while mixing the intermediate raw material (emulsion matrix) that has been emulsified and the foaming agent. Then, inside the blasting hole 10, the intermediate raw material and the foaming agent chemically react to foam and sensitize, and thus function as an explosive (main charge 24).

[0018] After loading the main charge 24 into the blasting hole 10, the stemming 28 is loaded into the blasting hole 10 with a predetermined interval above the main charge 24 loaded in the blasting hole 10. At least a part of the stemming 28 is filled in the bag body 35 and loaded into the blasting hole 10 as shown in FIG. 2. The material of the bag body 35 is not particularly limited, and it is preferable that the bag body 35 can be filled with the stemming 28 and expands as the filling amount increases from the viewpoint of being fixed smoothly and firmly inside the blasting hole 10.

[0019] The bag body 35 may be made of, for example, plastic, rubber, or elastomer. Examples of plastics include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polyvinyl chloride, and nylon. Examples of rubber include natural rubber, nitrile rubber, silicone rubber, styrene-butadiene rubber, urethane rubber, and fluororubber. Examples of elastomers include olefin-based, vinyl chloride-based, and urethane-based elastomers. With such materials, damage to the leg wire (not shown) of the detonator sandwiched between the inner wall surface 10A of the bursting hole 10 and the bag body 35 can be sufficiently suppressed.

[0020] A tubular (hollow) bag body 35 may be used. For example, the tip of the tube is tied and closed to form an empty bag, which is inserted into the bursting hole 10 from the tip side of the empty bag. After inserting to a predetermined depth, the filling 28a is filled from the base end side (upper end side) of the empty bag. For filling the filling 28a, a rod material such as a ramming rod may be used to push the filling 28a introduced into the empty bag toward the tip side (lower end side) of the empty bag. In this way, a bag body 35 filled with the filling is obtained. By sufficiently packing the filling 28a into the bag body 35, the bag body 35 is fixed inside the bursting hole 10. As a result, the bag body 35 (filling 28a) can be smoothly and sufficiently fixed at a distance from the increasing die 24. In this way, by loading with the filling 28a filled in the bag body 35 in the bursting hole 10, the leg wire and the filling 28a do not come into direct contact, and the concern about leg wire damage can be sufficiently reduced.

[0021] By increasing the distance between the bag body 35 (the filled material 28a) and the booster 24, a region 26 containing at least one of air and water is provided between the booster 24 and the bag body 35. The region 26 contains at least one of air and water. Due to the bag body 35 fixed inside the blasting hole 10, the region 26 of the blasting hole 10 is in a state as if it were capped with a large solid object. When such a region 26 contains air, the energy generated by the explosion is reflected within the region 26, improving the fragmentation effect. Also, when the region 26 contains water, the water pressure rises during the explosion, improving the fragmentation effect. In either case of air and water, while replacing the explosive with the region 26, the energy generated by the explosion can be efficiently utilized for fragmentation. Also, by the generation of secondary waves, crushed stones with small particle sizes can be obtained.

[0022] A part of the filled material 28 loaded into the blasting hole 10 may be loaded in a state of being filled in the bag body 35, and the other part of the filled material 28 may be loaded outside the bag body 35 inside the blasting hole 10. Then, as shown in FIG. 3, the filled material 28b loaded on the bag body 35 enters between the bag body 35 and the inner wall surface 10A of the blasting hole 10 and is sandwiched between the bag body 35 and the inner wall surface 10A. Such a filled material 28b meshes with the filled material 28a filled in the bag body 35 through the bag body 35, suppressing the bag body 35 from falling below the blasting hole 10. Therefore, the blasting operation can be performed more stably. Also, since the region 26 between the bag body 35 and the booster 24 can be firmly sealed, the shock wave generated by the explosion can be fully and effectively utilized for fragmentation.

[0023] The mass ratio of the filled material 28a filled in the bag body 35 to the entire filled material 28 may be 0.05 or more, and may also be 0.1 or more. Thereby, since the function as a cap is sufficiently exerted, the shock wave generated by the explosion is further suppressed from propagating from the opening of the blasting hole to the outside, and the shock wave can be more effectively utilized for fragmentation. The mass ratio of the filled material 28a filled in the bag body 35 to the entire filled material 28 may be 0.5 or less, and may also be 0.4 or less. Thereby, the working time required for the preparation of the blasting can be further shortened.

[0024] As shown in FIG. 2, the upper end 35A of the bag body 35 may be connected to a support body 50 disposed outside the bursting hole 10. Thereby, it is possible to sufficiently prevent the bag body 35 from falling downward. The support body 50 may be, for example, a sandbag. The support body 50 may be disposed at an arbitrary position on the ground surface 42 (free surface) of FIG. 1.

[0025] As the filling material 28, the chips 52 (shavings) generated when the bursting hole 10 is drilled with a heavy machine such as a drilling machine may be used, or separately prepared crushed sand, crushed stones (including aggregates), etc. may be used. Since the chips 52 have a small particle size, if they are used as the filling material as they are without using the bag body 35 as in the prior art, the sealing effect of the bursting hole 10 may be insufficient, and there may be a risk of the filling material being blown up during blasting and flying stones hitting mining equipment and surrounding houses. On the other hand, in this embodiment, since the chips 52 are put into the bag body 35 and used, the above problems can be avoided even when the chips 52 with a small particle size are used as the filling material 28, and blasting can be performed while further reducing low-frequency sound waves. Further, since the filling material 28 contains such chips 52, the cost required for blasting can be reduced.

[0026] Specifically, the amount of crushed stones used for the filling material 28 can be reduced, and the labor for carrying in and storing the crushed stones can be reduced. The particle size of the chips 52 used for the filling material 28 may be 30 mm or less, or may be 10 mm or less. The chips 52 having such a small particle size can be used as the filling material 28. This particle size can be measured, for example, using vernier calipers. The particle size of the non-spherical chips 52 is the maximum value among the measured values measured with vernier calipers.

[0027] The ratio (Lb / L) of the length Lb of the bag body 35 (the portion filled with the filling material) to the overall length L of the blasting hole 10 may be 0.01 or more, and may also be 0.02 or more. Thereby, the shock wave generated by blasting is sufficiently suppressed from propagating to the outside from the opening 12 of the blasting hole 10, and the shock wave can be sufficiently effectively utilized for crushing. Lb / L may be 0.2 or less, may be 0.15 or less, and may also be 0.1 or less. Thereby, the bag body 35 can be held sufficiently stably within the blasting hole 10. The overall length L and the length Lb are measured along the longitudinal direction of the blasting hole 10.

[0028] Returning to FIG. 1, the ratio (L2 / L) of the length of the region 26 (the length of the interval: L2) to the overall length L of the blasting hole 10 may be 0.1 or more, and may also be 0.15 or more. Thereby, the low-frequency sound and flying stones during blasting can be sufficiently reduced. Also, the amount of explosive used can be sufficiently reduced. Further, the particle size of the crushed stones after blasting can be made sufficiently small and the variation can be made small. L2 / L may be 0.4 or less, and may also be 0.3 or less. Thereby, a decrease in blasting efficiency can be suppressed. The length L2 of the interval is measured along the longitudinal direction of the blasting hole 10.

[0029] The ratio (L3 / L) of the loading length of the filling material 28 (the length of the filling material 28: L3) to the overall length L of the blasting hole 10 may be 0.15 or more, may be 0.2 or more, and may also be 0.25 or more. Thereby, the shock wave generated by blasting is sufficiently suppressed from propagating to the outside from the opening 12 of the blasting hole 10, and the shock wave can be sufficiently effectively utilized for crushing. L3 / L may be 0.45 or less, and may also be 0.4 or less. Thereby, a decrease in blasting efficiency is suppressed and the time required for preparation of blasting can be reduced. The length L3 of the filling material 28 is measured along the longitudinal direction of the blasting hole 10.

[0030] Since the bag body 35 is firmly fixed within the blasting hole 10, the ratio (L3 / R) of the length L3 of the filling 28 to the resistance R may be less than 1.8, and may also be less than 1.5. Thereby, the usage amount of the filling 28 can be reduced, and the working time can be further shortened. The ratio (L3 / R) may be 0.6 or more, or 0.7 or more. Thereby, sufficiently finely granulated crushed materials can be obtained.

[0031] The ratio (L2 / L1) of the length L2 of the interval to the length (length of explosive: L1) from the bottom surface of the blasting hole 10 to the upper surface of the booster die 24 may be 0.2 to 0.6, and may be 0.5 to 0.6. Thereby, the usage amount of the explosive can be sufficiently reduced, and the blasting efficiency can be made sufficiently high. Also, the low-frequency sound and flying rocks during blasting can be sufficiently reduced. Also, the particle size of the crushed stones after blasting can be made sufficiently small and the variation can be made small. The length L1 of the explosive is measured along the longitudinal direction of the blasting hole 10.

[0032] As shown in FIG. 1, in the blasting preparation method of the present embodiment, a blasting hole 10 in which a detonator 20, a parent die 22, a booster die 24, and a filling 28 are installed in this order from the bottom can be obtained. The same process may be repeated to prepare a plurality of blasting holes 10 having the same structure. The detonator 20 in the blasting hole 10 and the blaster 30 installed on the ground surface 42 are connected by a leg wire (not shown).

[0033] A blasting method according to an embodiment has a blasting step of performing blasting in the blasting hole 10 in which a detonator 20, a parent die 22, a booster die 24, and a filling 28 are installed in this order, obtained by the above-described blasting preparation method. A plurality of blasting holes 10 as shown in FIG. 1 may be prepared and blasting may be performed simultaneously or continuously using the plurality of blasting holes 10. In the blasting step, the detonator 20 is ignited and detonated by energization from the blaster 30 provided in each blasting hole 10, the parent die 22 is detonated, the booster die 24 is detonated by the detonation of the parent die 22, and the rock mass 40 is blasted, and the blasting is established.

[0034] In the blasting hole 10, a detonator 20, a main die 22, and an intensifying die 24 are fixed inside the blasting hole 10 in a state where a part of the packed material 28, i.e., the packed material 28a, is filled in the bag body 35. Since a part of the packed material 28 (the packed material 28a) is filled in the bag body 35, the blasting hole 10 is in a state as if capped with a large solid object. Such a bag body 35 can suppress damage to the leg wires of the detonator and can be smoothly fixed with a space from the intensifying die 24 in the blasting hole 10. Therefore, the working time for preparing the blasting can be sufficiently shortened. Further, since the bag body 35 is firmly fixed in the blasting hole 10, the energy generated by the explosion can be efficiently used for crushing, and the occurrence of back break can be suppressed. Back break refers to a phenomenon in which a crack occurs on the right side of the blasting hole 10 when blasting is performed at the blasting hole 10 in FIG. 1.

[0035] FIG. 4(A) is a photograph showing a state when back break did not occur due to blasting. On the other hand, FIG. 4(B) is a photograph showing a state when back break occurred due to blasting. According to the blasting method of the present embodiment, the occurrence of back break as shown in FIG. 4(B) can be sufficiently suppressed, and the state as shown in FIG. 4(A) can be achieved.

[0036] The bag body 35 and the inner wall surface 10A of the blasting hole 10 are engaged with each other by the packed material 28b outside the bag body 35. For this reason, the bag body 35 is more firmly fixed inside the blasting hole 10. Therefore, the propagation of the shock wave generated by the blasting from the opening 12 of the blasting hole 10 to the outside can be sufficiently suppressed, and the shock wave can be sufficiently effectively used for crushing. For this reason, it becomes possible to effectively use the explosive, and the powder unit can be reduced to reduce the cost. Further, since the amount of flying stones during blasting can also be reduced, the safety can be improved.

[0037] The above blasting method may be carried out in a limestone mine to collect raw limestone, and may have a process of adjusting the particle size of the raw limestone to produce limestone. The particle size adjustment may be carried out using a sieve after crushing the raw stone with a crusher. In this way, limestone with a sufficiently small and uniform particle size can be obtained. The uses of the limestone obtained in this way include raw materials for quicklime (uses: building materials, paper making, heating agents, desiccants, etc.), raw materials for slaked lime (for agriculture, etc.), and cement raw materials. The particle size of the limestone for cement raw materials may be, for example, 30 mm or less. The particle size of the limestone for quicklime and slaked lime may be, for example, 100 mm or less. These particle sizes can also be measured using, for example, calipers.

[0038] Since the above blasting preparation method and blasting method can sufficiently shorten the working time for blasting preparation, limestone can be smoothly produced at a low manufacturing cost. In addition, limestone with a small and uniform particle size can be obtained. If such limestone is used as, for example, a cement raw material, the load on each crusher such as a raw material mill can be reduced, and cement can be efficiently produced.

[0039] Also, when a situation occurs where blasting is temporarily stopped to recover the leg wire due to some factor such as misfiring of the detonator 20, in the case of the above blasting preparation method and blasting method, since at least a part of the stemming 28 is filled in the bag body 35 and loaded into the blast hole 10, the operation of recovering the leg wire from the blast hole 10 can be smoothly carried out. In addition, it is possible to prevent the leg wire from being damaged by friction with the stemming or a paper plug. In this way, while sufficiently suppressing the damage to the leg wire, the leg wire can be smoothly recovered in a short time.

[0040] The embodiments of the blasting preparation method and the blasting method have been described above, but the present invention is not limited to the above embodiments at all. For example, in the above embodiment, the upper end 35A of the bag body 35 was tied to the support body 50, but this is not necessarily essential. It is not essential to pull out the upper end of the bag body 35 to the outside of the blasting hole 10, and it may be fixed inside the blasting hole 10 so that the entire bag body 35 is embedded inside the blasting hole 10. Even with such a structure, the bag body 35 is stably fixed inside the blasting hole 10 by the frictional force with the inner wall surface 10A of the blasting hole 10.

[0041] The present invention includes, for example, the following contents. [1] A blasting preparation method having a loading step of filling a blasting hole with a filling material after loading a main die and an amplifier die on a detonator installed at the bottom of the blasting hole, In the loading step, a bag body filled with at least a part of the filling material is fixed in the blasting hole at a distance from the amplifier die, and a region containing at least one of air and water is provided between the amplifier die and the bag body. [2] The blasting preparation method according to [1], wherein the amplifier die is an aqueous explosive. [3] The blasting preparation method according to [1] or [2], wherein the main die is an aqueous explosive or a cast booster. [4] The blasting preparation method according to any one of [1] to [3], wherein the length L2 of the interval with respect to the length L1 of the explosive including the main die and the amplifier die is 0.5 to 0.6. [5] In the loading step, after loading the amplifier die into the blasting hole, a tubular empty bag is inserted, and the filling material is filled into the empty bag from the opening on the upper end side of the empty bag to obtain the bag body fixed inside the blasting hole. The blasting preparation method according to any one of [1] to [4]. [6] The blasting preparation method according to any one of [1] to [5], wherein in the loading step, the upper end of the bag body is fixed to a support body disposed outside the blasting hole. [7] The blasting preparation method according to any one of [1] to [6], wherein the filling material contains milled powder. [8] The blasting hole formation step of forming the blasting holes in the rock mass of the limestone mine before the charging step, the blasting preparation method according to any one of [1] to [7]. [9] After the blasting preparation method according to any one of [1] to [8] above, a blasting method having a blasting step of performing blasting in the blasting holes.

Example

[0042] The content of the present invention will be described in more detail with reference to the examples and comparative examples, but the present invention is not limited to the following examples.

[0043] A plurality of blasting experiments with different conditions were conducted as follows. In each blasting experiment, the working time, blasting efficiency (total explosive amount / ore amount), presence or absence of damage to the leg wires, and ease of recovery of the leg wires were evaluated. The specific procedures and evaluation methods were as follows.

[0044] In each example and each comparative example, the following materials were used. · Detonator: Manufactured by ORICA, product name: UT600 · Parent die (cast booster): Manufactured by ORICA, product name: Yinguang Booster · Booster die (bulk emulsion explosive): BULK CIVEC PRODUCTS (product name, manufactured by ORICA, a mixture of intermediate raw materials and foaming agents. The contained components of the intermediate raw materials: ammonium nitrate, oils, etc.) were loaded into the blasting holes while mixing at the blasting site. · Polyethylene tube (thickness: 0.09 - 0.11 mm, folding diameter: 150 mm): Manufactured by Ishikawa Co., product name: PE paper tube roll

[0045] (Example 1: Air deck blasting) In a limestone mine, a total of 10 blast holes with a diameter of 95 mm were drilled at equal intervals of 4.0 m at a point where the rock face height H: 7.7 m and resistance R: 3.4 m. A hydraulic crawler drill was used to drill the blast holes. The total length L of each blast hole was as shown in Table 1. The 10 blast holes were drilled in a straight line. The cuttings generated by the drilling were left to rest near the blast holes. A detonator connected to a leg wire was installed on the bottom of the blast hole. The top end of the leg wire was connected to a blasting device installed outside the opening of the blast hole (on the ground surface). A parent die was loaded in the blast hole so as to cover the detonator. Next, an additional die was loaded on top of the parent die while mixing explosives and foaming agents. The additional die was loaded so that the length L1 of the explosives from the bottom of the blast hole to the top of the additional die was the length shown in Table 1.

[0046] Next, one end of a polyethylene tube (polytube) was tied tightly, and the polytube was inserted into the blast hole with the one end facing downward. A filler rod was inserted from the other end (top end) of the polytube, and the insertion depth into the blast hole was adjusted so that the length from the knot at the bottom end of the polytube to the ground surface (length of filler L3) was 4.0 m. 8 kg of swarf (grain size: 10 mm or less) was introduced as filler from the opening on the top end side of the polytube, and the swarf was filled into the polytube.

[0047] The upper opening of the poly tube was closed by twisting the upper part while removing the air from the part of the poly tube that was not filled with cuttings (upper part). The upper part of the poly tube was wrapped around and fixed to the sandbag placed outside the blast hole. In this way, the bag was installed in the blast hole. After that, the same amount of cuttings as that filled in the poly tube was introduced into the blast hole, and about 24 kg of cuttings was filled on top of the bag. In this way, cuttings were also filled on the outside of the bag. In other words, cuttings were filled between the side of the part of the bag that was filled with cuttings and the inner wall surface of the blast hole, and between the upper end of the part of the bag that was filled with cuttings and the opening of the blast hole (ground surface). The length Lb of the part of the bag that was filled with cuttings (filling) was 1.2 m.

[0048] The mass ratio of the filling in the bag to the whole filling (the sum of the filling in the bag and the filling outside the bag) was approximately 0.3. The length L2 of the interval between the lower end of the bag fixed inside the blasting hole and the upper surface of the booster die (the length along the longitudinal direction of the blasting hole) was 2.0 m. No tension was applied to the upper part of the bag wrapped and fixed around the sandbag, and the bag itself was firmly fixed by the frictional force with the inner wall surface of the blasting hole.

[0049] From the time when the parent die was started to be loaded into the blasting hole until the time required to fill the blasting hole opening (ground surface) with cuttings and fix the upper end of the poly tube to the sandbag, it was measured as the working time per hole. The average value of the working time was as shown in Table 2. Thereafter, using a blaster, 10 blasting holes were simultaneously blasted. The total explosive amount (parent die + booster die) of the 10 blasting holes, the amount of ore crushed by the blasting (the amount of limestone), the amount of ore per blasting hole, and the total explosive amount per unit amount of ore were as shown in Table 2.

[0050] When there was no concern about damage to the leg wire connecting the detonator and the blaster in the visual inspection before blasting, and the blasting by the blaster was carried out as planned, it was evaluated as "no" concern about damage to the leg wire connecting the detonator and the blaster. On the other hand, when there was concern about damage to the leg wire connecting the detonator and the blaster in the visual inspection before blasting, or when the blaster was activated but no blasting occurred, it was evaluated as "yes" concern about damage to the leg wire. The evaluation results were as shown in Table 2.

[0051] (Examples 2 and 3: Air deck blasting) Except that at least one of the bench height H, the number of holes, the length L1 of the explosive, the length L2 of the interval, and the length L3 of the filling of the limestone mine was changed as shown in Table 1, air deck blasting was carried out in the same manner as in Example 1. Each evaluation result was as shown in Table 2.

[0052] (Example 4: Water deck blasting) The face height H, resistance R, number of holes, total length L of the blast holes, length L1 of the explosive, length L2 of the interval, and length L3 of the stemming of the limestone mine were set as shown in Table 1, and blasting was carried out in the same manner as in Example 1 except that the space (length L2) between the lower end of the bag fixed inside the blast hole due to the inflow of groundwater and the upper surface of the booster was completely filled with water. Each evaluation result was as shown in Table 2.

[0053] (Comparative Example 1: Air deck blasting) Instead of the poly tube filled with stemming powder, paper in which the explosive was packaged was rolled up and inserted using a tamping rod, and a paper plug was fixed inside the blast hole. The length L2 of the space between the lower end of the paper plug fixed inside the blast hole and the upper surface of the booster was 2.0 m. Then, the stemming powder used in Example 1 was introduced into the blast hole, and about 32 kg of stemming powder was filled on the paper plug to make a stemming.

[0054] The time required from the start of loading the main charge into the blast hole until the filling of the stemming powder was completed up to the opening (ground surface) of the blast hole was measured as the working time per hole. The average value of the working time was as shown in Table 2. Then, using a detonator, five blast holes were blasted simultaneously. Each evaluation result was as shown in Table 2.

[0055] (Comparative Examples 2 and 3: Air deck blasting) Air deck blasting was carried out in the same manner as in Comparative Example 1 except that at least one of the number of holes, hole spacing, total length L of the blast holes, length L1 of the explosive, and length L2 of the interval was changed as shown in Table 1. Each evaluation result was as shown in Table 2.

[0056] (Comparative Example 4: Single charge blasting) At a point in the limestone mine face with a face height H of 4.4 m and a resistance R of 3.3 m, a blasting hole with a diameter of 95 mm was drilled using a hydraulic crawler drill. The total length L of the blasting hole was as shown in Table 1. A detonator with the leg wire connected was installed on the bottom surface of the blasting hole. The upper end of the leg wire was connected to a blasting machine installed outside the opening (ground surface) of the blasting hole. A primer was loaded to cover the detonator installed on the bottom surface of the blasting hole, and an extender was loaded while mixing explosive and foaming agent on top of the primer. The extender was loaded so that the length L1 of the explosive from the bottom surface of the blasting hole to the upper surface of the extender was the length shown in Table 1. The total explosive amount (primer + extender) of the blasting hole was as shown in Table 2. The same primer and extender as in Example 1 were used.

[0057] Subsequently, without providing a gap, cuttings were introduced and filled up to the opening (ground surface) of the blasting hole as stemming on top of the extender. The length L3 of the stemming was as shown in Table 1. Blasting was carried out in the same manner as in Example 1 using the blasting hole thus obtained, and each evaluation was carried out in the same manner as in Example 1. The evaluation results were as shown in Table 2.

[0058]

Table 1

[0059]

Table 2

[0060] As shown in Table 1 and Table 2, the working time could be sufficiently shortened in the examples compared to the comparative examples. In Comparative Examples 1 to 3, time was required for the work of fixing so that the paper plug would not fall and the work of filling the cuttings, and the working time was longer than in the examples. In Comparative Example 4, when loading the extender (bulk emulsion explosive), it was necessary to wait until foaming was completed, and the working time was the longest. In Example 4, although the area between the lower end of the bag body and the upper surface of the extender contained groundwater, it could be sufficiently crushed by blasting. It was confirmed that Examples 1 to 4 had a lower value of "total explosive amount / ore amount" than Comparative Example 4 and could crush the rock mass with high blasting efficiency.

[0061] In each example, the occurrence of back break as shown in FIG. 4(B) was sufficiently suppressed, and it was confirmed from this point that the energy of the explosion could be efficiently used for crushing. On the other hand, in Comparative Example 4, although the blasting efficiency (total explosive amount / ore amount) was relatively high, a back break of 3 m or more occurred as shown in FIG. 4(B), which hindered the entry of the heavy machine for forming the next blast hole.

[0062] In Examples 1 to 4, large pieces did not occur, and finely granulated limestone raw stones could be obtained. This is considered to be due to the fact that the bag body was firmly fixed in the blast hole.

Industrial Applicability

[0063] It is possible to provide a blasting preparation method and a blasting method capable of sufficiently shortening the working time for blasting preparation and efficiently using the energy generated by the explosion for crushing.

Explanation of Signs

[0064] 10... Blast hole, 10A... Inner wall surface, 12... Opening, 20... Detonator, 22... Parent die, 24... Booster die, 26... Region, 28, 28a, 28b... Filler, 30... Blaster, 35... Bag body, 35A... Upper end, 40... Rock mass, 41... Face, 42... Ground surface, 50... Support, 52... Spoil.

Claims

1. A blasting preparation method having a loading step of loading a parent die and an amplifier die onto a detonator installed at the bottom of a blasting hole, and then loading a filling material into the blasting hole, wherein: In the loading step, a bag body filled with at least a part of the filling material is fixed at a distance from the amplifier die in the blasting hole, and a region containing at least one of air and water is provided between the amplifier die and the bag body. Blasting preparation method.

2. The blasting preparation method according to claim 1, wherein the amplifier die is an aqueous explosive.

3. The blasting preparation method according to claim 1 or 2, wherein the parent die is an aqueous explosive or a cast booster.

4. The blasting preparation method according to claim 1 or 2, wherein the length L2 of the interval with respect to the length L1 of the explosive including the parent die and the amplifier die is 0.5 to 0.

6.

5. In the loading step, after loading the amplifier die into the blasting hole, a tubular empty bag is inserted, and the filling material is filled into the empty bag from the opening on the upper end side of the empty bag to obtain the bag body fixed inside the blasting hole. The blasting preparation method according to claim 1 or 2.

6. The blasting preparation method according to claim 1 or 2, wherein in the loading step, the upper end of the bag body is fixed to a support body disposed outside the blasting hole.

7. The blasting preparation method according to claim 1 or 2, wherein the filling material contains fines.

8. The blasting preparation method according to claim 1 or 2, further having a blasting hole forming step of forming the blasting hole in the rock mass of a limestone mine before the loading step.

9. A blasting method having a blasting step of performing blasting in the blasting hole after the blasting preparation method according to claim 1 or 2.

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