Application of Large Diameter Deep Hole Blasting in Cutting Vertical Slot of Thick Ore Body Stope

0 Preface

Molybdenum and tungsten Shibayama plurality Heavy metal ore mining a large diameter deep phase step stope for mining subsequent filling method, stope (N1-7) large diameter (Φ165) deep hole drilling, the rig configuration CS150D . The rock drilling boundary of the stope is 74.3m×15m, and the longitudinal direction is arranged in five rows, numbered from 1 to 5, and the horizontal direction is arranged in 28 rows, numbered C1～C28. The row spacing of the blasthole is 3.75m, the row spacing is 2.8m, the cutting yard adopts the cutting patio slot, the blasting range is C1～C4, the first to fourth column holes and the auxiliary cutting patio slot deep hole T1～T8, the spacing 2 .15m, a total of 27 holes, the actual total depth of blasting is 259m. A total of 148 holes in the stope, total hole depth 5806.74m
1 Project Overview
The blasting design is to cut the vertical trough in the 450m middle section of the N1-7 stope. The blasting site is located in the N1-7 stope in the middle section of 400m. The blastholes are located in the ore body. The blasting is all downward vertical blastholes, the spacing between C1, C2 and C3 is 2.15m, the spacing between C3 and C4 is 2.8m; the spacing of holes is generally 3.75m. The design and actual construction of the blasthole position deviation is large, the specific blasthole position is shown in Figure 1.

2 blasting design
2.1 Calculation of explosives and its material consumption
Calculate the charge per metre of the blasthole: q = π × r2 × l × p = 19.42 kg. The charge density was taken as 1.10 g/cm3 based on empirical data, and the charge per meter was calculated to be 19.43 kg. Actually, two Φ145mm×500mm (600mm) drug packs per meter are installed. The weight of a single drug pack is about 10kg, and the charge per meter is 20kg.
The amount of collapse in this trough is about 30,634.46 tons, requiring 2790.00 kg of explosives (including 240 kg of test explosion), and the explosive consumption is 0.91 kg/t. The blasting construction design was based on the actual construction and the following adjustments were made.
(1) Due to the first rectangular trough blasting at the eastern end of the N1-7 stope, the first hole is filled with the bottom hole and then the hole is charged. The primer is slid down from the top, and the near 1~2m bottom ore is not blasted. Therefore, this design blasting has adjusted the amount of individual pores.
(2) Because the position of the blasthole at the cutting patio is relatively far, the distance between other adjacent blastholes is relatively close, and the position of the construction blasthole and the designed blasthole is quite different. The single-stage detonation by the hole will destroy the peripheral blasthole orifice to ensure After the detonation, the charge is safe and reliable, and the design of the full-hole segmental blasting is changed to a layered blasting grooving.
Each MS has 2 MS detonators per layer, totaling 156 rounds (including 2 detonators). When the hole is extended, the detonator is issued twice.
2.2 Charge structure design
The blasting kit has a specification of Φ145mm×50cm, a weight of 10kg/bag, and a detonating detonator is loaded into the intermediate emulsion explosive charge. After the bottom of the hole is blocked by the crater plug, after 1.5m sand is installed, the charge is 1.5m, and each layer is filled with 3~4 medicine packs. The charge length is 1.5~2.0m, and the interval is sand. Filling, the orifice is blocked for 2.0m, and the charge structure is shown in Figure 2.

2.3 detonation network design

Detonation method: delay detonator - detonating tube detonator - detonating cord - detonating tube detonator, double detonation network. Sectional blasting between the three layers of the drug in the hole, the two layers of the drug are all detonated by the double-tube detonating tube detonator, and the lower layer leads the upper layer to detonate. The firing order of the blasthole is shown in Figure 3.

The blasting network is led to the detonation by a detonator of the detonator to the safety point outside the stope to ensure that all the underground personnel are safely evacuated to the surface during the blasting, and the equipment is evacuated to a safety point of 100m. The detonating network is connected in parallel, and the outer detonating tubes are grouped in rows. The blasting network is shown in Figure 4 and Figure 5.

2.4 Blasting technical and economic indicators
According to the above design, large-diameter deep-hole blasting is carried out in the stope (N1-7), and the technical and economic indicators are: blasting 4 rows of deep hole width 7.10m; blasting compensation space 247.64m3 (hole bottom to explosion stack height not allowed) Less than 3m); stratified blasting ore body volume 942.60m3; blasting compensation coefficient 1.26; blasting hole depth total 259.00m, including test explosion 13m; blasting explosive consumption 2790.00kg, including test explosion 240kg; layered blasting ore The amount is 30,634.46t; the number of blasting holes in the cutting vertical groove is 27.00; the single blasting cost of cutting vertical groove is 0.91kg/t; the amount of blasting per square meter in the cutting vertical blasting is 11.83t/m.

2.5 safe distance calculation
(1) Shock wave safety distance

Where: RK———the minimum safe distance, m;
KK———Safety factor, take 40 (for general buildings)
70, the staff takes 25 to 60);
Q———The total weight of the explosives in this explosion is 2550kg.
It is determined that there are no important equipments and buildings near the blasting operation point, and the exit distance from the ground surface is outside the safety distance, and the shock wave will not cause damage.
(2) Seismic wave safety distance:

In the formula: q———The maximum amount of dose is taken by the differential blasting, 320kg (the maximum charge of a single section);
v———Protect the speed allowed by the object particle (20cm/s for medium hard rock);
k———The value of medium hard rock is 150～250, this time is 200 according to experience;
α————take 1.5~1.8, this time take 1.6 according to experience.
The blasting is a downhole blasting. The rock near the working point is relatively stable and has no important structures. The straight line distance from the surface is about 400m, and there is no need for protection on the surface; the damage caused by seismic waves can be ignored.
(3) The scope of impact of blasting gas:

Where: Rg—the safe distance of the blasting gas, m;
Q———The total amount of explosives exploded, 1.81t;
Kg - coefficient, average 160.
The horizontal distance of the blasting operation point from the surface of the surface is about 400m. Before the operation of the well, it is necessary to detect the harmful gas, and then reach the safe value before going down the well.
3 conclusions
The large-diameter deep-hole blasting has been successfully applied in the cutting blasting of the thick-body ore body of the Chaishan polymetallic ore in the Shizhuyuan, and has achieved good blasting effect, which is consistent with the blasting economic technical indicators in the design of the blasting scheme. The technology and protective measures have been put in place and the safety situation is good. This blasting method can be popularized and applied in the mining of other thick ore bodies.
references:
[1] The first layer blasting construction design of the 450m middle section of the N1-7 stope [R]. Changsha: Changsha Mining Research Institute Co., Ltd., 2015(9).
[2] Wang Xuguang. Blasting design and construction [M]. Beijing: Metallurgical Industry Press, 2012.
[3] Jie Shijun. Underground mining of metal deposits [M]. Beijing: Metallurgical Industry Press.
[4] Chen Yunxiang, Zhang Jirong, Li Yuncao, et al. Large-diameter deep hole blasting of hard rock and large block rate control technology [J]. Mining Research and Development, 2014 (04): 115-118, 127.
[5] Yang Qingping, Wang Yuming, Liu Xiaohui, et al. Qian segment subsequent filling method and Application Test [J] Greek copper ore ratio to deep blasting. Mining Technology, 2014 (01): 1-3, 6.
[6] Large blasting safety regulations [M]. Beijing: State Bureau of Technical Supervision.
[7] Yu Renbing, Chen Zhen, Zeng Yong, et al. Numerical simulation of deep hole blasting hole network parameters in Tonglushan Mine [J]. Mining Technology, 2014 (02): 82-85.
[8] Yang Rongyan, Mu Yongqing, Liu Guangxing. Experimental study on deep well blasting of Luolu Group Mining Company [J]. Mining Technology, 2012 (06): 68-72.