Optimization of blasting parameters of Gaocun stope based on lateral blasting funnel test
The total reserves of mineral resources in the Gaocun mining site of Maanshan Iron and Steel Co., Ltd. is 346 million tons, the average grade is TFe20.48%, and the service life is 24a. The mine design and production scale is 7 million t/a, the total stripping and stripping is 18.5 million tons, the step design height is 12m, the final slope angle is 35°~42°, the highest elevation of the stope is +102m, and the lowest elevation is -186m. The final slope height is 288m [1]. The mine adopts deep hole and hole-by-hole millisecond blasting. The KY250A roller rig is perforated with a hole diameter of 250mm, mainly based on emulsion explosives.
Due to the influence of various factors such as mineral rock conditions and mining parameters, the quality of mine blasting is poor, the large block rate is high, and the root phenomenon is more prominent, which directly restricts the mining cost of enterprises. It is urgent to carry out optimization research on blasting parameters. Through the lateral blasting funnel test, the optimization analysis of the blasting parameters of the stope is carried out, and the reasonable blasting parameters are determined to improve the blasting quality and improve the production efficiency.
1 lateral blasting funnel test
1.1 Test materials
The test explosive is a 180mm emulsion explosive for production, with a density of 1.1 to 1.35g/cm3, a blasting distance of 5cm, and a detonation speed of 3200m/s. High-precision detonator detonator Shandong silver-Chemical Group Co., Ltd., each hole 2 is made.
1.2 test plan
Under the premise of determining safety, the lateral blasting funnel test was carried out in combination with the production blasting of Gaocun stope. The diameter of the test blasthole was 250mm. In order not to affect the normal production of the mine, the single test blasthole is arranged at a location other than 2 times the distance from the main blasting zone; in order to eliminate the influence of the production blast on the test hole, the test hole is detonated prior to the main blasting zone. After the blasting, the parameters of the blasting funnel are measured, and the composition of the blasting block is photographed to be analyzed by the block image.
According to Livingston's blasting funnel theory, when explosives are blasted in rock, the energy and velocity transmitted to the rock depends on factors such as rock properties, explosive properties, quality of the package, and depth of drug embedding [2-3]. The depth of the drug pack is a key factor affecting the blasting effect. For the lateral blasting funnel test, the resistance line is equivalent to the depth of the drug pack embedded in the Livingston blasting funnel test. In order to determine the impact of the blasting resistance line on the blasting quality, the design adopts the method of increasing and decreasing the resistance line, and compares and analyzes the blasting effect of the normal blasting resistance line. By changing the size of the single hole blasting resistance line, the optimal blasting parameters are found.
The blasting funnel test has a total of 6 groups, Scheme 1 and Scheme 2 are normal production resistance line tests, Schemes 3 and 4 are reduction resistance line tests, and Schemes 5 and 6 are increased resistance line tests. The blasting parameters for each test are shown in Table 1.
1.3 Analysis of test results
At present, image analysis is one of the commonly used methods for analyzing blasting blockiness [4-5]. Here, the length of the rock block is more than 800mm, and the block size of the blasting funnel is shown in Figure 1 (the length of the standard bar is 10cm). The statistics of the bulk rate of each blasting are shown in Figure 2. The measurement results of the blasting funnel parameters after the test are shown in Table 2.
It can be seen from Fig. 2 and Table 2 that for the scheme 3 and scheme 4 for reducing the resistance line, the blasting hopper angle, the blasting funnel volume and the blasting volume of the blasting chamber are larger than other schemes, and the bulk rate and the explosive unit consumption of the two schemes are larger. They are smaller than other schemes; among them, the maximum length of blasting of scheme 3 is 81.8m3/m, the unit consumption of explosives is the smallest, it is 0.28kg/m3, and the rate of bulk is the smallest, 0.98%. For schemes 5 and 6, which increase the resistance line, compared with other schemes, the blasting funnel angle is reduced, and the explosive unit consumption and bulk rate are increased. Among them, scheme 5 has the largest unit consumption of 0.49 kg/m3, which is large. The block rate is the largest, at 7.53%.
According to Livingston's blasting funnel theory, the volume of the blasting funnel gradually increases with the increase of the depth of embedding. When the depth of embedding is the optimum depth, the volume of the funnel reaches a peak. Then, the depth of the explosive is increased, and the volume of the funnel is rapidly increased. Reduce the trend.
The test results show that under the current blasting parameters of the mine, reducing the resistance line within a certain range can increase the amount of blasting of the rice, reduce the unit consumption of explosives, reduce the cost of blasting operations, and help reduce the bulk rate and improve. Blasting quality; the current resistance line of the mine is greater than the optimal resistance line, that is, the embedding depth corresponding to the explosive in the Livingston blasting funnel test is greater than the optimum depth, so the resistance line should be appropriately lowered to make it close to the best resistance line. For the best blasting effect.
2 field parameter optimization
2.1 General hard rock
For general hard ore rocks, according to the preliminary design parameters, the bulk rate of the blasting area of ​​the normal production pore network parameters is 4.52%; after the optimization of the parameters of the blasting hole network, the large block rate is 2.45%, and the large block is significantly reduced. The block rate is reduced by 45.6 percentage points, and the optimization effect is remarkable. From the perspective of the on-site blasting effect, the explosion pile is loosely concentrated, the blockiness is uniform, and the root phenomenon is not seen, which is convenient for shovel loading and transportation. See Table 3 for comparison of blasting parameters before and after optimization.
2.2 Special hard rock
In the past, when blasting in a particularly hard ore zone, the blasthole burden area was small, the unit consumption was high, and the bulk was large, and the bulk rate was 7% to 10%.
After optimizing the parameters of the blasting hole network in the hard ore in the northern part of the stope, the bulk rate is reduced to 4.37%, the blasting quality is obviously improved, the shovel loading efficiency is improved, and the blasting cost is reduced. See Table 4 for comparison of blasting parameters before and after optimization.
3 on-site construction control measures
(1) According to the lithological conditions at different positions of the stope, adjust the parameters of the blasting hole network in time to obtain a good blasting effect.
(2) Strengthen the on-site construction management and accurately measure the drilling position; before charging, measure the parameters such as the inclination angle and the depth of the hole to control the parameters such as the charge amount and the length of the blockage.
(3) The blasting engineering technician shall measure the minimum resistance line of each drill hole in the first row before charging, and consider adjusting the dose or spacing for the site where the reverse slope or large crack is formed. The area where the chassis resistance line is too large should be treated to meet the blasting requirements. If the orifice resistance line is too small, the length of the packing should be appropriately increased.
(4) When there is any phenomenon such as blockage or card hole in the charging process, the drug should be stopped and dredged in time; after the drug is finished, it should be checked and accepted, and then the filling and networking work should be carried out after the acceptance is passed.
4 Conclusion
According to the lateral blasting funnel test, the current resistance line of the mine is larger than the best resistance line. By optimizing the blasting parameters of the general hard ore and special hard ore in the mine, the bulk rate is 4.52% and 7% respectively. ~10%, reduced to 2.45% and 4.37%, improved blasting quality, improved production efficiency, and provided important guidance for safe and efficient production of mines. In order to ensure the quality of blasting, scientific management should be strengthened during on-site construction; effective control measures should be taken according to site conditions and measures according to local conditions.
references
[1] Bi Kecheng. Large aperture blasting technology in Experiment open Application Takamura iron ore [J] in. Modern Mining, 2011 (7): 85-86.
[2] Wang Xuguang. Blasting manual [M]. Beijing: Metallurgy Industry Press, 2010.
[3] Wang Yujie. Blasting Engineering [M]. Wuhan: Wuhan University of Technology Press, 2009.
[4] Lu Lin. Application of image processing technology in rock mass block analysis [D]. Wuhan: Wuhan University of Technology, 2011.
[5] Lin Daze. The progress of research on the evaluation method of burst pile degree [J]. Chinese Journal of Safety Science, 2003, 13 (9): 9-13.
Article source: "Modern Mining"; 2016.10;
Author: Chen Neng leather; Maanshan Iron & Steel Group Mining Co., Ltd;
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