Xingshan iron ore Mining Industry Company, is a first underground mines, no-pillar sublevel caving, production capacity was 3.2 million t / a, high stage 150m, high segment 18.75m, is a pioneering tunneling, mining blasting The whole process of modernized mining mountain, which is improved by shredding, ventilation, drainage and shotcrete support, is dedicated to creating “domestic first-class underground minesâ€, among which the development and mining and excavation projects are produced by Atlas Copco of Sweden. The Boomer 281 excavation trolley was perforated, and the blasting used 2# rock emulsion explosive, large-section one-time blasting, the section size was 17.43~20.35m2, and the annual blasting engineering volume was 6000m (105,000m3). At present, the mining industry is severe, and the comprehensive cost of blasting accounts for about 15% of the cost of boring. Therefore, it is of great practical significance to study the technology of reducing the cost of blasting construction and reducing the unit consumption of explosives. Since 2016, Xingshan Iron Mine has carried out research on blasting and blasting technology. Based on the blasting blasting technology, the blasting design is optimized, and the standardization management of blasting blasting is carried out to achieve the goal of reducing efficiency and efficiency of blasting engineering. From the initial stage of production of Xingshan Iron Mine to the end of 2015, the blasting technology has been greatly improved, and the single consumption of blasting explosives in the mines in the same industry in the country is at an advanced level (Table 1). Based on many test results at home and abroad, good blasthole packing can not only increase the blasting energy, but also make the blasting more uniform and uniform, and also greatly enhance the throwing effect, while saving more than 10% of explosives. Where ls is the length of the plug, m; L is the depth of the blasthole, 3.3m; D is the detonation velocity of the explosive, 4000m / s; Vp is the longitudinal wave velocity of the rock, 5000m / s; Ï1 is the density of the mud, 2550kg / m3; Ï0 For the explosive density, 950kg/m3. According to the blasting conditions and rock properties of Xingshan Iron Mine, the reasonable packing length ls≈0.4m is calculated, which can be used as the reference value for the design of the blasting blasting of Xingshan Iron Mine. Where f is the rock solidity coefficient, take 12; S is the roadway design cross-sectional area, taking 17.43m2. It is calculated that N=51, plus the number of holes in the slotted hole, there are 55 blastholes, which are basically consistent with the blasting design parameters currently implemented by Xingshan Iron Mine. In the arrangement of the blasthole, it can be adjusted in combination with the blasthole charge structure. On the basis of optimization of the blasthole charge structure, the arrangement of the blasthole is adjusted. The minimum resistance line of the blasting blasthole must be satisfied In the formula, Wmin is the minimum resistance line of blasting, mm; d is the diameter of the blasthole, 45mm. The minimum resistance line Wmin=450~900mm is calculated. The blasthole arrangement principle is to reduce the charge coefficient of the auxiliary hole and the peripheral hole blasthole when the number of blastholes is constant, and to adjust the blastholes at different levels to increase the thickness of the blast layer and reduce the row spacing of the auxiliary holes. The 55 hole blasting design of the Xingshan iron mine roadway is that the peripheral eye hole distance is unchanged from 500mm, the thickness of the light explosion layer is increased to 800mm, and the first to fourth auxiliary hole row spacing is reduced to 750~850mm. The optimized blasthole arrangement is shown in Figure 1. 4 practical effects In the beginning of 2016, Xingshan Iron Mine promoted the blasting of blasting mud, and searched for yellow mud with high viscosity around Qian'an. At the same time, it purchased PNJ-A type mud blasting machine and organized blasting to learn to make cannon and blasthole filling technology. According to the optimized blasting design parameters, the practice was carried out on the spot and achieved good results. In 2016, the average explosive consumption per blasting was 2.09kg/m3, which was 5.3 percentage points lower than the 2.2kg/m3 in 2015. The optimized blasting design meets the current production needs of Xingshan Iron Mine and reduces the cost of excavating pyrotechnics. , contributed to the cost reduction and efficiency work. The main indicators of single blasting before and after optimization are shown in Table 5. Through the theoretical analysis of the blasthole packing technology, the advantages of good blasthole packing are recognized, and the reasonable clogging length is designed. On this basis, the blasting design parameters are optimized and the blasting energy distribution is improved. Through experiment and practice, after the blasting, the rock mass is reduced and uniform, the throwing distance is reduced, the explosion pile is relatively concentrated, which is conducive to decoration, and the smooth blasting effect is improved. At the same time, the blasting explosive unit consumption is further reduced, and the blasting comprehensive cost is reduced. . The application of blasting blasthole packing technology provides an effective way for cost reduction and efficiency improvement of Xingshan Iron Mine Tunneling Blasting Project, and has good promotion value in similar mines. Highway Guardrail Steel Sheet Roll Forming Machine is the equipment to press, through rolling and cold bending, the colored steel sheet with thickness of 0.3-1.0 mm into two waves pattern sheet. The Highway Guardrail Roll Forming Machine is suitable for the use of highway guardrail and has the following characteristic: light weight, high strength, rich colors and being earthquake-proof and fireproof, etc. Now the machine is widely used. It has advantage of pretty appearance, durable using ,long life ,low energy consumption and so on. Highway Guardrail Roll Forming Machine Highway Guardrail Roll Forming Machine,Guardrail Roll Forming Machine,Guardrail Machine,Guardrail Forming Machine Botou Hongyuan Forming Machine Co.,Ltd , https://www.tilemakingmachinery.com
1Xingshan Iron Mine Tunneling Technical Parameters
The Xingshan Iron Mine Drilling and Rocking Equipment is Boomer281 type trolley. The equipment has advanced performance and high rock drilling efficiency. The drill bit length is 3.7m, the drilling depth is 3.3m, and the roadway design section specification is 17.43m2 ( 4.8m×3.9m), the diameter of the blasthole is 45mm, the hole diameter of the gutter is 102mm, and the peripheral eye is charged with uncoupled space. In order to reduce the damage of the explosive around the roadway, the surrounding eye adopts 32mm×330mm rock. The emulsified drug roll is 0.3kg per roll, and the other blastholes are made of 36mm×450mm rock emulsified drug roll, 0.5kg per roll. Only the peripheral eye is simply filled with an explosive cartridge. The detonating equipment has a second delay non-electrical tube, a millisecond delay non-electric tube and a detonating cord. 
2 boring blasting technology
2.1 Theory of blasthole packing
From the development history of engineering blasting technology, the development of blasting theory has experienced a tortuous process, which can be roughly divided into three stages: the first stage is the theoretical stage of stress wave breaking rock, and it is considered that the rock breaking and displacement are mainly caused by stress wave. The second stage is the theoretical stage of rock breaking by gas expansion. It is considered that the rock fracture is the process of gas stress field and gas intrusion directly into the crack; the third stage is the combination of stress wave and gas pressure. At the theoretical stage of rock breaking, the theory has been consistently recognized. It is believed that the explosive stress wave, the gas expansion pressure and the reflected tensile wave all contribute to the rock fragmentation and cannot be neglected. This theory clearly points out the stuffing of the mud. Increasing the duration of gas pressure, breaking and reducing throwing rocks all play an important role. On the basis of the third stage theory, the Chinese Academy of Railway Sciences has tested the distribution ratio of explosive energy of strip charges. The shock wave (including stress wave) can account for 43.7%, and the gas expansion energy accounts for 56.3%. Experimental studies have shown that 50% of the gas energy is lost from the orifice without tamping. Therefore, the purpose of the blasthole packing is to fully exert the rock breaking effect of the gas expansion energy of more than half of the total energy of the explosion [1-3].
The blasting test of blasthole packing at home and abroad has been carried out many times. In 2003, the blasting laboratory of China Railway Science Research Institute tested the effects of different stuffing materials and found that the blasting of the blasthole was tightly filled with concrete, and the broken piece was small and uniform. The block movement speed is the largest; under the same conditions, the clay is filled and blasted, the blockiness increases, and the movement speed of the fragments decreases; while the rock powder packing effect is the worst. Through comprehensive comparison of test data, clay is more suitable for engineering construction in terms of construction conditions and effects. In order to obtain the actual clay filling effect of tunnel hard rock blasting, the former Ministry of Railways blasting research group also combined the Qinling tunnel excavation blasting to carry out the productivity test of the mud-filling effect. The test results are shown in Table 2.
2.2 Determination of the length of the blasthole
In combination with the theory, the stuffed mud must have sufficient resistance to impact and anti-burst time to achieve satisfactory results, so the increase in the mass of the plug can lead to an increase in the volume of the cavity, but the volume of the cavity after the plug mass exceeds the critical value. It will not continue to increase. If the length of the packing is too large, it will cause blasting and other effects that affect the blasting. Therefore, it is necessary to further check the length of the mud filling. In order to find a reasonable length of packing, domestic and foreign scholars have carried out a large number of experimental studies and summarized practical experience, with reference to the empirical formulas issued by the China Railway Science Research Institute to determine:
3 optimization of blasting parameters
After the promotion of the blasthole mud filling measures in Xingshan Iron Mine, the blasting energy loss of the blasthole is reduced. According to the above theory, the explosive medicinal amount can be reduced by about 10%. Therefore, the existing blasting design parameters are optimized, mainly from the blasthole arrangement. Research on both aspects of the blasthole charge structure.
3.1 Calculation of the number of blastholes
First determine the number of blastholes, using the empirical formula:
3.2 Charge structure and optimization of blasthole arrangement
The arrangement of the blasthole should be fully combined with the optimization of the charging structure. Under the premise of ensuring the smooth blasting effect and the blasting effect of the boring hole, the blasting hole is charged by the blasting blasthole to reduce the blasting energy loss. The structure was optimized, the auxiliary hole reduced the charge factor by 19.7%, and the total charge was reduced by about 12%. The optimization results of the blasthole charge coefficient are shown in Table 3. The comparison of the blasting charge design parameters is shown in Table 4.
5 Conclusion
references
[1] Chen Guoshan, Weng Chunlin. Underground mining metal [M]. Beijing: Metallurgical Industry Press, 2008.
[2] Dai Jun, Wang Shuren, Wang Yeping. Blasting Engineering [M]. Beijing: Mechanical Industry Press, 2007.
[3] Yu Yalun. Engineering blasting theory and technology [M]. Beijing: Metallurgical Industry Press, 2008
Article source: "Modern Mining", 2017.4
Author: Chen Guorui; Shougang iron ore mining company Xingshan Copyright: