GOLD Zijin copper ore rock blasting design choice = KQG150Y stepped hole drill 165mm inclined drilling, blasting copper deep hole bench blasting zone. The parameters of the hole network are: hole spacing 7m, row spacing 6m, step height 12m, ultra deep 2~2.5m, perforation depth 13.5m. The single-hole charge does not exceed 200kg, the charge density is calculated from 0.35~0.48kg/m3, the plum-shaped cloth hole method, the charge structure adopts continuous coupling charge, and the detonation method selects the row-by-row differential detonation. At present, the main problems in the step blasting of Zijinshan Gold-Copper Mine are that the blasting quality is not ideal and the blasting cost is high. It is concentrated in the large-scale output, the bottom-end retention, the consumption of explosives during blasting operations, the consumption of blasting equipment is large, and the single High consumption and other aspects. According to past experience, the production of large blocks mostly occurs in the unfilled section of the orifice, and the retention of the roots is mainly due to the unreasonable control of the ultra-deep or poor quality of the bottom of the blasthole [1-3]. During the blasting operation of open pit mines, the determination of blasting parameters will directly affect the blasting effect and mine economic benefits. This study is aimed at the problems in the blasting operation of the Zijinshan gold-copper mine and optimizes the blasting parameters.
1 blasting scheme design
1.1 Scheme 1 In the first scheme, the blasthole inclination angle is 90°, and a total of 11 holes are arranged (Fig. 1). The average super deep is 1.43 m, the step height is 15 m, the block rate is 15%, and the root rate is 4.5%. The blasting parameters of this scheme are shown in Table 1.
In the blasting process of the first scheme, the average ultra-deep depth is 1.43m, and the large block rate is higher (15%), which increases the secondary blasting workload. The shape of the explosion pile is not ideal, which increases the workload of the shipment. The bottom of the pile is large, the site is uneven, the transportation of the car is not convenient, and the machine wears seriously when the site is leveled, which is not conducive to production [2].
1.2 Scheme 2 In Scheme 2, the blasting angle of the blasthole is 85°, and a total of 20 holes are arranged (Fig. 2). The average ultra-deep is 1.5m, the step height is 15m, the block rate is 12%, and the rooting rate is 3.9%. The blasting parameters of the scheme are: vertical length 16.4m, oblique length 16.5m, ultra-deep 1.4m, adjustable charge 240kg, charge length 11.4m, filling length 5.1m, section height 15m, explosive unit consumption 0.6kg, hole spacing, resistance line values ​​are shown in Table 2.
In the second blasting process of Scheme 2, the average ultra-deep 1.5m, the bulk rate has decreased, but still high (12%), there is still a large secondary blasting workload, the shape of the explosion pile is not ideal, and the base is more. The site is not flat. If it is transported by car, it is difficult to meet the production needs and the cost is high.
1.3 Scheme 3 In the third scheme, when the inclination angle of the blasthole is 80°, 22 holes are arranged (Fig. 3), the average ultra-deep is 3.09m, the step height is 15m, the block rate is 8%, and the rooting rate is 0.9%. The blasting parameters of this scheme are shown in Table 3.
The blasting average of the scheme 3 is 3.09m, and the bulk rate has decreased, but it is still high (8%). There is still a large secondary blasting workload, and the shape of the blasting pile is not ideal. If the car is transported, the rock in the blasting area is relatively hard, so the ultra-deep is set to 3.09m, and there is almost no root, but the concave phenomenon is more serious, and the site must be leveled to meet the transportation conditions of the car [4].
1.4 Scheme 4 Scheme 4 has a blasthole inclination of 75° and a total of 28 holes (Fig. 4). The average depth is 3.3m, the step height is 10m, the block rate is 3%, and the root rate is 0.8%. The blasting parameters of this scheme are shown in Table 4.
The blast hole inclination angle of scheme 4 is 75°, the average ultra-deep depth is 3.3m, and the large block rate is greatly reduced to 3%. Basically, there is no need for secondary blasting. The shape of the blasting pile is ideal, the base is obviously reduced, and it can be transported normally by car. Perform site leveling.
2 Analysis of blasting effect According to the blasting test results of the four schemes, the relationship between the inclination angle of the blasthole and the large block rate (Fig. 5), the relationship between the ultra-deep and the large block rate (Fig. 6), the inclination angle of the blasthole and the base are drawn. The relationship curve (Fig. 7) and the relationship between ultradeep and root rate (Fig. 8) [5]. It can be seen from Fig. 5 to Fig. 8 that when the blast hole inclination angle is 75° and the ultra deep depth is 2.4 m, the bulk rate and the root rate are the lowest.
3 Conclusion Taking the Zijinshan gold-copper mine as an example, the problems existing in the blasting operation of the mine were analyzed, and the blasting test scheme was designed and compared. The results showed that the base rate and the bulk rate were 75°. The minimum is reached, which has certain reference value for optimizing the blasting operation effect of the mine.
References [1] Wang Surprise. Study on blasting design and optimization of Sanhe Jinneng open pit [D]. Changsha: Changsha Research Institute of Mining and Metallurgy, 2014.
[2] Chen Lei, Wu Lei, Li Xia Bank. The role of water medium at the bottom of the blasthole in step blasting [J]. Metal Mine, 2013 (5): 34-35.
[3] Li Chaoliang. Study on blasting effect and comprehensive cost optimization of open pit mines [J]. Mining and Metallurgical Engineering, 2012 (6): 55-56.
[4] Pan Zejun, Liu Lixia, Guo Yina. Development trend of deep hole blasting technology in open pit mine [J]. Mining Engineering, 2012 (3): 123-124.
[5] Shi Xuejiao, Peng Chao. Reasons of Huangmailing phosphorus ore open-air blasting boulder and measures [J]. Blasting, 2012 (1): 65-67.
Article source: "Modern Mining"; 2017.1
Author: Blue Zhonglin; Zijin Mining Group Co., Ltd. Zijinshan Gold and Copper Mine
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