Hard ore excavation technology in front of the mountain iron mine

Yanqianshan iron ore hanging wall ore production of major work site for the stope East, West Wall, the eastern end of help is responsible for the eastern hanging wall ore excavation, perforation and mining ore scraper out of work. In the initial stage of Dongbang production, straight-type gutters were used, with 100 perforations per hole, 3m hole depth, 1.5m average footage, and less digging. After the blasting, the core is broken, which will cause collapse and blockage when the next hole is perforated. Hole; the utilization of the blasthole is 50%, which is lower than the average level of the national blasthole utilization rate (70%-80%); the single consumption of explosives is high, nearly double the national average level, and there are a large number of residual eyes remaining after the blasting. It is difficult to make the next piercing. The existence of the above problems leads to a large number of blasting perforations, low blasting efficiency and high blasting cost. To this end, this study studied the hard ore excavation technology of the Dongshan Iron Mine.
1 Mine geological overview
Iron easternmost Yanqianshan help in tunneling banded magnetite quartzite rock formations clip, a magnet mainly composed of quartz rock, quartzite magnet amphiboles, actinolite, garnet, quartzite, etc., for the main structure and a layered block structure Structure, hardness coefficient is 12 ~ 17, the physical and mechanical parameters of iron ore in the area are shown in Table 1. See Table 2 for the blastability classification criteria of the rock in front of the mountain iron ore. See Table 3 for the blasting standard of the main rock (mineral) stone in the mining area.

It can be seen from Table 3 that the ore of the eastern end of the mountain iron ore mine has poor explosiveness and is of grade V, which is a rock type that is difficult to blast.
2 hard ore tunneling technology
2.1 troughing scheme
When blasting in the roadway, the function of the grooving hole is to create a groove cavity as the free surface on the working surface, which creates favorable conditions for other blasthole blasting. Therefore, the arrangement of the grooving hole is extremely important. According to the section of the roadway, the nature of the rock and the geological structure, the arrangement of the groove is composed of three types: inclined empty groove, parallel hole straight groove, and mixed groove [1-3].
2.1.1 Parallel hole straight groove
The parallel hole hole straight groove method is perpendicular to the working surface, and the hole depth is not limited. The hole is parallel and the resistance line is uniform. It is usually divided into a crack groove, a barrel groove, and a spiral groove. This study used a five-star grooved cloth. The middle boring hole acts as the first blasting hole, and the surrounding four holes can provide free surface and compensation space. The four holes are symmetrically arranged around the middle boring hole. After the first boring hole is detonated, the middle is empty. The hole is penetrated to provide compensation space and free surface for the rear blast hole. The parameters of the blasthole are: hole diameter 102mm, hole depth 3200mm, boring hole aperture 45mm, hole depth 3200mm, all arranged perpendicular to the face of the face. The effect of blasthole arrangement and blasting test are shown in Figure 1 and Figure 2, respectively. It can be seen from Fig. 1 and Fig. 2 that the space of the gutter cavity is small after the blasting of the gutter, and the throwing effect of the gutter cavity is not ideal, and it can not provide sufficient compensation space for the auxiliary hole blasting, which is easy to cause less blasting footage and more residual holes, so parallel space The hole straight groove is not suitable for the east end of the mountain mine.

2.1.2 inclined hole groove
The inclined hole grooving method is characterized in that the sipe hole is obliquely intersected with the working surface, and is generally divided into a wedge-shaped groove, a tapered groove, and a one-way groove. The wedge-shaped gutter test was carried out on the site of the Dongbang operation area. It was found that the angle of the blasthole was difficult to grasp during the perforation process, and the hole punching was inconvenient. The precision of the blasthole construction is relatively high, and the construction angle must be strictly controlled. It is difficult to ensure the construction quality, and it is easy to cause the blastholes to penetrate each other and affect the blasting effect. In addition, the mine uses an imported rock drilling rig to drill the arm. The long operation of the drill pipe is not flexible and the construction is difficult. It can be seen that the inclined hole groove is not suitable for use in the mining area of ​​the mine.
2.1.3 barrel and inclined hole mixing groove
By analyzing the properties of the rock at the eastern end of the mountain front iron ore and combining with the practical experience of production, it is considered that the ideal gutter arrangement should satisfy the simple form and easy operation, and form enough cavities after blasting. In this study, through the field test explosion and analysis, a bucket-and-tilt hole mixing method was proposed. The grooving method wears 7 10° parallel inclined holes, and the middle boring hole serves as the first blasting hole, and 6 holes are evenly distributed around the center hole to provide compensation space. After the first boring hole is detonated, the middle 6 A hollow hole is penetrated to provide a compensation space and a free surface for the rear slotted hole. The parameters of the blasthole and the arrangement of the blasthole are as follows: the hole diameter of the groove is 45mm and the hole depth is 3200mm; the center hole of the groove and the auxiliary hole are 10° to the center line of the tunnel faceway; the center hole is charged, and the 6 auxiliary holes are not installed. Medicine; 4 two-stage detonation holes are 200mm from a hole, and are uniformly distributed in a diamond shape around the auxiliary hole. The effects of blasthole arrangement and blasting test are shown in Figure 3 and Figure 4, respectively.

After repeated blasting tests, it is found that the method has better effect of grooving. Firstly, the sloping groove helps the ore to be thrown. The average depth of the sulcus is 3.0m. Secondly, the space of the groove is large, which provides enough for the back channel. The large compensation space and the free surface; finally, the grooved hole is a slanted hole, and the position of the hole does not coincide with the position of the bottom of the hole, which solves the problem that the core of the groove is broken after blasting, and the heart piercing of the blasting groove is difficult. To this end, in this study, the east side of the mountain iron ore operation area uses a barrel-shaped and inclined-hole mixing method.
2.2 Auxiliary hole and peripheral hole arrangement
The principle of arrangement of auxiliary holes and peripheral holes: 1 uniform hole, not only make full use of explosive energy, but also ensure collapse according to the design outline; 2 bottom hole arrangement should ensure that the large resistance line is overcome and the water in the hole is reduced. Factors affecting the number of blastholes are rock properties, explosive power, roadway section specifications, free surface conditions, blasthole depth, charge factor, charge method, and packing method. The on-site blasting test found that the number of original perforations was too much after optimizing the gutter method, and it was necessary to re-optimize the arrangement of the auxiliary holes and peripheral holes, and gradually reduce the number of blast holes. After several tests, the number of perforations was reduced to 55, the peripheral hole was 200mm from the inside, 100mm from the bottom of the hole, the camber angle was 5°, the hole depth was 3m, the side wall was 500mm from the top eye, and the bottom hole was 660mm. After the boring hole and the peripheral hole are arranged, the auxiliary hole is arranged, and the auxiliary hole is arranged as a free surface layer, and is evenly distributed on the surface of the blasted rock body. Firstly, three sections of blasting holes (6#~9#) holes are arranged, 300mm away from the second section holes; secondly, four stages of blasting holes (10#～13# holes) are arranged, 500mm from the three sections of holes; five stages of blasting holes are arranged again (14 #～17#孔), 500mm from the four-section hole; then arrange six-stage detonation holes (18#~25# holes); finally arrange three seven-stage detonation holes, 640mm from the six-segment holes. The blasthole arrangement is shown in Figure 5.

2.3 specification piercing operation
The design of the tunneling and perforation is solidified, and the internal training of the working area is carried out, so that the layout of the gun hole in Fig. 5 is shown (unit: mm). The construction personnel fully grasp the tunneling and perforating technology. Formulate the excavation and perforation specifications, track and supervise management in time during the perforation process, and timely correct and assess to ensure the quality of the eye. Before the tunneling, use the inkjet groove, the side wall and the top arc to ensure the direction and size of the roadway. First determine the position of the center groove, and the carriage 281 or 282 drilling rock drill arm upwardly flat, upper and lower arms to keep the angle constant, press the start position pre-designed through the center hole of the groove, only during the vertical perforations Moving parallel to the left and right, the angle between the boom and the arm remains unchanged, ensuring that the slot hole is aligned with the center of the lane. The slotted hole and the auxiliary hole must be completed with low impact to ensure accurate piercing angle and position. When the other holes start to perforate, the hole depth should be less than 500mm, and the low-speed impact must be carried out. Except for the bottom hole, the other holes have a flow gradient of 1% to 2% from the bottom of the hole to the hole to ensure that the dross in the hole is clean and there is no product. water.
2.4 Optimize blasting design and strengthen blasting management
2.4.1 Optimized blasting design
Due to the large size of the boring hole clamp, the blasting optimization design was carried out in this study. In view of the fact that the bottom plate eye needs to overcome the bottom plate resistance line and the upper slag, the charge amount is large, and the auxiliary hole is gradually reduced from the inside to the outside. The blasting parameters are shown in Table 4.

First, the slot hole is detonated, and then the auxiliary hole is detonated one by one. After the auxiliary hole is blasted, the side wall hole and the top eye are detonated, and finally the bottom eye is detonated. All blastholes are reverse detonated, 1MS detonator is used outside the hole, and up to 10 detonators are connected to each detonator. The safe place is detonated with a detonator (Figure 6).

2.4.2 Strengthening blasting management
1 Before the gunpowder enters the blasting site, the blasting personnel shall use the gun stick to inspect the blasting hole. If it is found that the hole is blocked, it shall pass through the hole in time; 2 to ensure safe detonation and quasi-explosion, strictly in accordance with the design sequence (slot hole → auxiliary hole → Peripheral hole) detonation; 3 blastholes are charged according to the designed dose.
3 blasting effect
(1) Excavation costs. The number of perforations has been reduced from 100 to 55, saving the cost of drilling materials by 3001 yuan/m. The cost of the roadway excavation before the implementation of the excavation technology was 4,478 yuan/m, and the cost of the roadway excavation was reduced to 1,477 yuan/m. The unit consumption of explosives decreased from 3.18kg/t to 1.36kg/t. Due to the large reduction in the number of perforations, the equipment work table is greatly reduced, thereby reducing the equipment operation loss and saving the maintenance, maintenance and repair costs of the equipment.
(2) Driving efficiency. The roadway driving footage was increased from 1.5m/d to an average of 2.5m/d, the blasthole utilization rate was increased from 50% to 83%, and the monthly production volume was increased from an average of 60m/month to 130m/month.
(3) Operational safety. There are fewer residual holes in the working surface, which reduces the safety hazard of the perforation operation; the single consumption of gunpowder is reduced, the damage to the surrounding rock is reduced, and the stability of the surrounding rock is improved; the number of perforations is reduced by 1/2, and the working time is shortened by 1 time and shortened. The working time in the hazardous area reduces the risk of operation.
(4) Digging quality. After the blasting, the roadway is shaped and conformed to the design contour. After the smooth blasting, the clearly visible half-hole wall marks are left on the newly formed wall surface, which greatly reduces the over-excavation of the roadway and improves the construction quality.
(5) Labor intensity of employees. It effectively reduces the working time of tunneling perforation and blasting charge in each area, and reduces the labor intensity of employees.
4 Conclusion
In order to effectively solve the problems in the process of roadway excavation in the eastern end of the mountain front iron ore mine, the hard ore roadway excavation technology was studied. After a lot of theoretical analysis and experimental verification, the parameters of the excavation hole and the technical parameters of the blasting process were optimized. Good practical results can be used as reference for similar mining projects.
references
[1] Gu Yicheng. Blasting construction and safety [M]. Beijing: Metallurgy Industry Press, 2004.
[2] Wang Qing, Shi Weixiang. Mining science [M]. Beijing: Metallurgical Industry Press, 2001.
[3] Tao Songlin. Rock drilling and blasting [M]. Beijing: Metallurgical Industry Press, 1986.
Author: Mu Xiaohong; Anshan Iron and Steel Group Mining Technical School;
Chu Changqing ; Anshan Iron and Steel Group, Yanqianshan Iron Mine;
Article source: "Modern Mining"; 2016.6;
Copyright:

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