2020 m Ekou iron ore mine oxide content of more than segmented, structure greater impact than crushing, Platts expected coefficient of 10 ~ 11; 2020m middle less dense hard mineral lithology, Platts coefficient estimated 11 to 12, the average The density is 3.3t/m3. The surrounding rock of the ore body is mainly amphibolite , accompanied by quartzite containing chlorite, and the Platts coefficient is expected to be 8-10. At present, the mine is produced by sublevel caving without pillars [1-3], the height of the middle section is 40m, the section height is 12m, and the distance between the two entrances is 15m. The mine adopts the upward vertical fan-shaped medium-deep hole blasting method. The YGZ-90 rock drill is used to drill the fan-shaped hole. The blast hole surface is inclined at 90°, the aperture is 65mm, the fan-shaped hole angle is 45°, and the collapse step is the row spacing. That is, 1.8m, the bottom distance of the fan-shaped blasthole hole is 1.8m, the adjacent coefficient of the fan-shaped blasthole hole bottom is 1, and 13 blastholes are designed for each sector. In the course of practice, the above-mentioned parameters are more obvious: 1Because the blasthole is too dense, the ore crushing after blasting is uneven, which tends to cause a large number of holes in the middle and deep hole, which makes the consumption of secondary blasting explosive increase, and The mine easily leads to the large-scale jame out of the mine. During the mining process, the mining funnel of the stope can not be balanced, which affects the mining efficiency and reduces the productivity of the mining. 2 It is easy to cause the ore in the stope to be mixed with the waste rock. At the same time, if there is a large block of the mine outlet, it will limit the amount of ore; 3 easy to destroy the eyebrow line leads to buried holes, the front row can not charge, increase the resistance line and lead to the ceiling or large block. At this stage, the ore hardness above and below the 2020m section of the mine changes significantly. If the above blasting parameters are still used, the blasting effect will be affected. Therefore, the existing medium-deep hole blasting parameters of the mine should be optimized.
Optimization of deep hole blasting parameters in the middle section of 12020
1.1 Determination of the caving step The collapsing step should be consistent with the height of the collapse and the distance between the two approaches to ensure that the collapse of the ore is consistent with the ore ellipsoid. If the step size of the collapse is too large, the upper waste rock is inserted into the ellipsoid prematurely, causing the upper overburden to mix into the ore body and quickly reach the cut-off grade, causing the front-end ore body to be unable to be released and causing loss; If it is too small, the waste rock at the front end enters the position of the ore out prematurely, resulting in the loss of the upper ore. The calculation formula of the collapse step L is
In the formula (1), b is the short semi-axis of the ore-bearing ellipsoid along the approach direction, m; a is the long axis of the ore-leaving ellipsoid, m; θ is the axial flow angle of the ore-bearing body, (°).
According to the test results of ore ellipsoids under similar mine conditions, b is 3.6~4.2m, a is taken as 12m, θ is taken as 3°, and the parameters are substituted into the above formula: L=3.3~3 .9m. Therefore, the reasonable step size of the collapse should be 3.2 to 3.8 m. In this study, the step size of the iron ore collapse in the mouth of the mouth is 3.0 to 3.6 m. Considering the different ore properties of the upper and lower sections of the 2020m section of the Sakaguchi iron ore, L should be 3.6m above the middle section of 2020m and 3.2m below the middle section of 2020m.
1.2 Minimum resistance line and hole bottom distance adjustment Adjust the hole parameters of the oxidized ore body above the middle section of 2020m. To ensure the influence of the front row hole blasting on the rear row hole, the row spacing is still 1.8m, and the edge hole angle is 50°, the step of the collapse is 3.6m, so the front hole is 11 holes, the hole bottom distance is 2m, the rear hole is 12 holes, the hole bottom distance is 1.9m, and the blasting coefficient is 1.06. . By adopting the staggered arrangement of the front and rear rows of the blasthole, the extrusion action is increased, the bulk rate is reduced, and the collapse effect is improved. Below the middle section of the 2020m section of the Yankou Iron Mine, the idea of ​​reducing the resistance line and increasing the hole bottom distance is adopted. Therefore, the re-set row spacing is 1.6m, the hole bottom distance is increased to 2m, and each row collapses 2 rows, so that the bottom of the hole The product of the distance and the minimum resistance line is unchanged, the minimum resistance line is 1.6m, the blasting coefficient is 1.25, and the two rows of blastholes are arranged in a staggered manner, and two rows are detonated at a time. The detonation method can ensure uniform distribution of blasting energy, and by prolonging the action time of blasting energy, the number of large blocks can be significantly reduced, and the loss of ore depletion can be easily controlled and controlled, and the bayonet accident can be reduced.
1.3 Edge hole angle adjustment The previous hole angle of the mouth iron ore mine is 45°, the purpose is to shorten the hole depth and reduce the material consumption during piercing. The side hole angle test of a mine in Nanjing shows that when the angle of the hole is 50°~68°, the variation of the loss of the single-section ore loss is small, and it is beneficial to multi-segment under the condition of large hole angle. Mining. Increasing the edge angle of the mesopores can increase the fluidity of the ore body and reduce the depletion and loss of the ridge. Therefore, the edge angle of the hole is adjusted from 45° to 50°.
1.4 Explosive unit consumption The ideal blasting effect is related to rock blastability, explosive performance, blasting parameters and other factors. The lithology can calculate the unit consumption of explosives. The formula is
In the formula (2), k is the correction coefficient, generally 1.2 to 1.4, which is 1.3 in this study; f is the hardness coefficient of the ore, taking 10 to 12; Ï is the ore density, taking 3.3 t/m3. Considering that there are more oxidized ore bodies above the middle of 2020m, the ore is loose and the blastability is good. The hardness coefficient of ore is about 10, so the unit consumption of explosives is set to 0.297kg/t; the ore structure below 2020m is dense and hard. The integrity is good, the ore hardness coefficient is about 10, so the explosive unit consumption is set to 0.325kg/t.
2 blasthole design
2.12020m middle or higher oxidized ore body for oxidized ore body above 2020m, the diameter of the blasthole is 65mm, and 2 rows of blastholes are blasted at the same time. The hole bottom distance is 1.8~2.0m, and the hole hole angle is set to 50°. The average explosive consumption is 0.289kg/t, the blasting step is 3.6m, and the two rows of blastholes are staggered. There are 11 front holes, the total length of perforation is 144.32m, the length of charge is 113.74m, the charge factor is 78%, the charge of front blasthole is 318.5kg, and the consumption of ore unit explosive is 0.28kg/t. . The rear row of holes is 12, the total length of perforation is 154.99m, the length of charge is 119.05m, the charge factor is 77%, the charge of the rear blasthole is about 333.34kg, and the consumption of ore unit explosive is 0.292kg. /t. The arrangement of the blasthole is shown in Figure 1. See Table 1 for comparison of the arrangement parameters of the front and rear blastholes.
The hard primary ore body below 2.22020m is for the hard primary ore body below 2020m. The row spacing is set to 1.6m, the hole bottom distance is 2m, the edge hole angle is 50°, and the second row is exploded. The average consumption of explosives is average. It is 0.315kg/t, and the front and rear rows of the blasthole are staggered. The relevant parameters are shown in Table 2.
3 In the detonation sequence underground deep hole blasting, the interval between the holes is 25~50ms, the front and rear blasthole detonators are alternately arranged, U-shaped detonation, 4 holes detonator sections are the same, a total of 6 sections are used, the largest micro The difference interval is 50ms. The detonation method can reduce the block rate by colliding with the ore, and the block degree can be uniform, and the eyebrow line is intact. The detonation sequence after optimization in this study is shown in Figure 2.
4Comparative analysis of economic indicators At this stage, the number of holes per hole in the Yankou Iron Mine is 155.2m, the area of ​​the blasthole is 176.1m2, the row spacing is 1.8m, the amount of collapsing is 1014.34t, and the blasting consumes ammonium explosives. 322kg/time, the unit collapse amount is 6.53t/m, and the explosive consumption is 0.319kg. After optimization in the middle section of 2020m, the number of holes per hole in the blasting is 299.31m, the area of ​​the blasthole is 182.2m2, the row spacing is 1.8m, the stepping distance is 3.6m, the amount of collapsing is 2165t, and the explosive consumption of ammonium explosives is 619.2kg. / times, the unit collapse amount is 7.23t/m, and the explosive consumption is 0.286kg. After optimization in the middle section of 2020m, the number of holes in the blasting is 288.64m, the area of ​​the blasthole is 182.2m2, the row spacing is 1.6m, the stepping distance is 3.2m, the amount of collapsing is 1924t, and the blasting consumes 600. 3kg/time, the unit collapse amount is 6.67t/m, and the explosive consumption is 0.312kg.
In this study, the blasting parameters of the 2020m section of the Yankou Iron Mine were optimized respectively: above 12020m, the blasting step was adjusted from 1.8m to 3.6m, and the hole bottom distance was adjusted from 1.8m to 2m. The hole angle is adjusted from 45° to 50°, and the U-shaped adjustment is carried out in the detonation sequence; below the 22020m segment, the blasting step is adjusted from 1.8m to 3.2m, and the hole bottom distance is adjusted from 1.8m to 1.9m. The hole angle was adjusted from 45° to 50°, and the detonation sequence was U-shaped.
5 Conclusions The deficiencies in the blasting process of the Suikou Iron Mine are analyzed. The blasting parameters of the 2020m middle section of the mine are optimized. The blasthole design is carried out for the 2020m middle oxidized ore body and the 2020m middle and lower hard primary ore body. And optimized the detonation sequence. Practice shows that the above optimization design can help to reduce the bulk rate, increase the ore body fluidity, improve the collapse and mining efficiency, and have certain reference value for similar mines.
References [1] Wei Jianhai, Huang Xingyi, Ge Chao, et al. PFC2D-based numerical simulation of no-bottom sublevel caving method [J]. Modern Mining, 2015 (12): 30-31.
[2] Hu Baowen, Li Changhong, Wei Xiaoming. Influence of mining space change on the ground pressure of sublevel caving method without bottom column [J]. Metal mines, 2015 (12): 5-9.
[3] Zhou Zhigang, Hao Quanming, Yan Yingjie. Application of sublevel caving without pillar in the eastern mine of Bayan Obo Iron Mine [J]. Modern Mining, 2015 (11): 31-32.
Article source: "Modern Mining"; 2017.1
Author: Yin Haifeng; China Tibet Mining Co., Ltd.
Copyright:
Leisuwash EG Vehicle Wash Disinfectant Equipment
Vehicle Wash Disinfect Equipment,Touchless Car Wash,Touchless Vehicle Wash Disinfect Equipment,Leisuwash Vehicle Wash Disinfect Equipment
Hangzhou Leisu Cleaning Equipment Co.,Ltd , https://www.sdleisuwashtouchless.com