Blasting Technology of Baixiangshan Iron Mine Mine
Baixiangshan iron ore rock quality based on "engineering rock grading standards" (GB / T50218-2014) are III, IV grade ore required to support the project in 2015, support costs of 14% of the cost of mining . Ore bodies occur in medium-water-bearing strata, and multiple faults lead to strong aquifers in the ore-bearing strata and upper part of the ore-bearing strata. Due to engineering geological and hydrogeological conditions and the limitation of ore body shape with gentle inclination and small vertical thickness, 2015 Before the fourth quarter, the method used upper-port filling method mining, the cutting ratio was 5m/kt, the mining efficiency was low, the cutting ratio was high, the support cost was high, and the mine operation was difficult. In order to reduce the cutting ratio and support cost and improve mining efficiency, a low-cost, high-efficiency segmented empty field of 12m height is studied and designed in areas with good engineering geological and hydrogeological conditions and suitable ore body shape. Filling the mining method [1]. Whether the method can be successfully applied depends on whether the stability of the unsupported side 8.5m high after the blasting of the mine can allow the scraper to safely carry out the mining operation. In order to ensure the ideal effect of the post-empty filling method, this study analyzes the mine blasting technology.
1 blasting scheme safety technical requirements
The Baixiangshan iron ore mine is 6m wide and 12m high, of which the rocky roadway is 3.5m high and the step height is 8.5m (Fig. 1). Considering the impact of the blasting effect of the mine on the safety and efficiency of the mining operation, the mining of the adjacent two-step mining room and the working parameters of the rock drilling rig, the safety technical requirements for the blasting scheme are as follows: The end wall of the tank should be stable to ensure the safe discharge of the scraper; 2 the downward hole must be tilted forward, the ore is thrown forward after the explosion, the pile is away from the 8.5m high step surface and relatively concentrated, the block should be even, twice The small amount of crushing is convenient for the scraper to efficiently mine, and the mine can be safely mined at the bottom of the step; 3 the working distance from the drilling of the rock drilling rig and the side of the rocking roadway is 0.3m, and the side hole must be cambered. In order to ensure that the width of the blasting area of ​​the downward hole is as close as possible to the width of the rock tunnel (ie the width of the mine), more ore is recovered as much as possible, which is beneficial to the safe mining of the adjacent two-step mine. 4 The blasting parameters should be optimal and segmented. The detonation method minimizes the impact of blasting on the vibration of adjacent mines and reduces the consumption of blasting equipment [2].
2 blasting scheme
2.1 Deep hole blasting scheme in the mine
The robustness coefficient of the Baixiangshan iron ore mine is 8-12, which belongs to medium hard rock with a blasthole spacing of 1.75-2.10m. Referring to the values ​​of the diameter of the blasthole and the row spacing of the blastholes used in some mines in China (Table 1), the range of the blasthole spacing of the Baixiangshan can be obtained from 1.5 to 2.5 m. The study gradually scaled the row to 1.8m.
For parallel deep holes, the deep hole density coefficient is 0.8 to 1.1, and the combined mining field width is 6 m. After several tests, the hole spacing is determined to be 2 m.
2.2 Side wall control blasting scheme
The side wall of the cutting tank adopts smooth blasting technology, and the pre-splitting blasting technology is adopted on both sides of the mining room. The common point is that a row of dense holes are arranged on both sides and end walls of the mining room, and the small dose is not coupled with the charging method. The blasthole is not blocked; the difference is that the hole in the side wall of the cutting groove is detonated in the main blast hole, and the hole in the side of the mine is detonated before the main blast hole. The line charge density has the following relationship with the ultimate compressive strength and pore size:
Where q1 is the line charge density, g/m; σc is the ultimate compressive strength, MPa; d is the bore diameter, mm.
The σc of Baixiangshan ore is 107.6MPa (96.2～140.0MPa), d is 70mm, and it is substituted into the above formula, q1 is 238.9g/m. After many tests, the final q1 is 400g/m. The 32mm emulsified drug roll will be firmly tied to the detonating cord with tape, and 2 pieces per metre, and the bottom of the hole at the side of the mine is doubled. The spacing between the side holes is 0.56~0.84m, which is 0.8m according to the actual situation. According to the width of the stope (6m) and the layout of the main blasthole network parameters, after several tests, the side hole blasthole and main blast The pitch of the holes is 0.7 m.
2.3 Smooth blasting and medium-deep hole combined blasting scheme
The plan of forming the cutting groove by smooth blasting and medium-deep hole combined blasting is shown in Fig. 2 to Fig. 4. The blasting parameters of the cutting tank are shown in Table 2. In addition, the detonating cord is required to be 97m, the 32mm medicinal volume is 38.2kg, the ammonium explosive is 123.5kg, and the detonator is 5.
2.4 Pre-cracking blasting and medium-deep hole combined blasting scheme
The scheme of pre-splitting blasting and medium-deep hole combined blasting back to mining room is shown in Figure 5-8. The blasting parameters of the mine are shown in Table 3. In addition, the detonating cord is 190m, the 32mm medicine volume is 80.4kg, the ammonium explosive is 282kg, and the detonator is 4.
The safety technical requirements of the design of the blasting scheme of Baixiangshan Iron Mine were analyzed. The blasting scheme was optimized and the blasting parameters were optimized. Finally, the side wall controlled blasting scheme of the 12m high-segment empty field å—£ post-filling mining method was determined. The downward-to-medium-deep hole combined blasting scheme has certain reference value for similar mines.
references
[1] Zou Jun, Qiu Yu, Liu Jiadong. Application of segmented empty field post-filling mining method in the north and south Fenhe iron ore [J]. Modern Mining, 2016(2): 11-13.
[2] Yu Yalun. Engineering blasting theory and technology [M]. Beijing: Metallurgy Industry Press, 2004.
Article source: "Modern Mining"; 2016.10;
Author: Tang Tiejun, Chen fifty-nine, Liu Faping, Huangxiao Zhong, Zhou Lei; Magang Group Gushan mining companies;
Copyright:
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