Application of No-cutting Well Pulling Method in Mikeng Iron Mine

The main ore body of Makeng Mining is layered and layered, which occurs on the pseudo-integration surface between the clastic rocks of the Nanjing Group and the limestone of the Qixia Formation. The top plate of the 65-line 251 section of the West Section is limestone, some of which are marble and skarn, and the bottom is skarn and woodland sandstone . The ore body is nearly northeast, tending to the southwest, with a dip angle of about 50°, a strike length of about 300m, and an ore body thickness of 4 to 40m. Magnetic iron ore garnet mine, and between them there are garnet skarn, close ore structure for the massive structure. A weathered skarn is developed on the right side of the ore body, which is extremely broken, muddy and watery. There is a large fault in the bottom of the ore body, which is prone to collapse. The faults and fissures in the ore body are extremely developed, which is prone to blockage and collapse. The integrity and stability of the rock are poor, and the local rock is extremely broken. The mine uses a segmented empty field method, medium and deep hole section rock drilling, falling mine, flat bottom structure, and scraper mining. The constituent elements of the ore block: when the thickness of the ore body is greater than 20m, the vertical direction is arranged, the stage height is 100m, the section height is 12m, the approach spacing is 12.5m, the upper and lower sections are staggered, the phase crossing pulse spacing is 120m, and the 2m3 electric scraper passes the points. The section of the transport lane directly discharges the ore into the slippery well; when the thickness of the ore body is less than 20m, it is arranged along the direction of the ore body and is recovered along the vein. The traditional cutting patio troughing method is difficult to construct and has a large safety hazard. The non-cutting well-shaped medium-deep hole blasting groove method with progressively rising crater holes is adopted, and good use effect is obtained.
1 non-cutting patio troughing scheme
1.1 Principle of no-cutting well groove [1]
Using the cutting lane as the blasting free surface, using the millisecond blasting, the blastholes are sequentially blasted row by row, creating the blasting compensation space row by row, and finally forming the cutting groove. In addition, the one-time blasting also avoids the front row blasting to the rear row of guns. The influence of the hole is destroyed.
1.2 Arrangement and construction of blasting holes without cutting wells [2]
The YZ-90 rail-type rock drill is used to cut the slot of the slot, the diameter of the hole is 50-65mm, and the arrangement of the hole is shown in Figure 1. The YZ-90 type rail rock drill is used to drill the blastholes, the first to the fourth row, the spacing of each row of blastholes is 0.4m, and the rock drill is moved to the left or right after the construction of one row; the fifth to the eighth row After each row of construction is completed, it will be moved back 0.5m. The forward crater holes of the groove are on the same side. In order to prevent the groove from being unsatisfactory, and in order to make the groove space meet the space requirement of the normal blasthole, a row of reinforcement rows should be constructed 0.5m after retreating, and then 1 row of reinforcement rows should be constructed after 1m. In the front inclined hole slotted blasthole, the bottom distance of each row of holes is 1.6-1.8m, the bottom distance of each row of holes is 3.2-3.5m, and the bottom distance of the enhanced blasthole hole is 1.8m.

1.3 pull groove blasting
The porous granular ammonium fry is stirred with a binder, charged by an applicator, using a continuous reverse charge, a non-conducting blasting blasting network, and a millisecond delay blasting method. The space around 7m of the end of the cutting tunnel is used as the free surface and its blasting compensation space. According to the sorting number of the blasthole arrangement, the blasting is performed from low to high, and the blasting is performed once. The blasting scheme is shown in Table 1 and Table 2.

1.4 mining site mining
After the mine falls, the 2m3 electric scraper is used to discharge the ore directly into the chute through the sectional transport lane, and the ore after cutting the trough is exhausted as much as possible. Because the ore in the cutting trough is relatively broken, the personnel cannot enter the ore, and the remaining ore is reserved for the next section and then discharged.
2 security measures
(1) When drilling holes in medium and deep holes, the depth and angle of the blasthole should be controlled to prevent the blasthole from deviating from the design angle. The hole depth error should be less than 0.5m, the blasthole deflection error should be less than 2°; strictly implement the blasthole acceptance management system, the hole must be filled when the blasthole does not meet the requirements; use the artificial drug tube charge to control the orifice part The perforation does not have a length of charge, ensuring the quality of the medium-deep hole rock and charge.
(2) As the ore body cutting lane is broken, the front row of blastholes will easily affect the next row of blastholes, which will deform the next row of blastholes. It is necessary to use pre-charged drugs, and must be compacted; select reasonable rock drilling and blasting parameters according to the actual situation on the site to avoid the occurrence of vertical grooves and suspended ceilings after blasting.
(3) In order to ensure that the eyebrow line of the unblasted row is not damaged, it is required that the 7th and 8th rows of the groove of the groove are longer, and the hole is spaced apart, the longest is not more than 5m, and the shortest is not less than 2.5m.
(4) Because the surrounding rock is relatively broken, some of the blastholes are blocked, and each blasthole is required to be boring to ensure that the charge is in place.
3 Conclusion
The one-time pulling groove of the non-cutting patio solves the difficulty of constructing the cutting patio in the unstable mine section, and ensures the safety of the medium-deep hole falling mine slot. The uncut patio trough achieved the expected results, and the subsequent blastholes were able to blast normally.
(1) Cutting the patio pulling method When the construction of the cutting patio is carried out, the safety management is difficult, especially in the broken rock section, and safety accidents occur frequently. In the alleyway, the construction method of the no-cutting well forward blasting hole is adopted, which avoids the danger of the construction of the patio and has high construction safety.
(2) Reduce the cost of cutting the groove. Less construction of a cutting patio reduces the difficulty of safety management and mining costs.
(3) When the cutting patio is constructed by the trough method, the rock formation is broken, the construction height is not enough or the molding is poor, the trough cannot achieve the expected effect, and the ore loss rate is increased, and the recovery rate is reduced. The use of the non-cutting trough method avoids the above defects, reduces the ore loss rate, and improves the recovery rate.
references
[1] Ming Shixiang. A new method for self-grooving of non-cutting well-shaped deep hole blasting [J]. Metal mines, 2010 (3): 20-22.
[2] Wang Yongqi. Application of deep hole cutting trough once-forming technology in steep inclined ore body mining [J]. Chemical Minerals and Processing, 2012(3): 29-32.