0 Preface
Compared with the shallow hole falling mine, the middle and deep hole falling mine [1-3] workers are fixed in the rock drilling roadway and the mining operation, and the personnel do not need to enter the goaf, the operation is relatively safe; with the medium and deep hole chisel The development of rock equipment, the efficiency of fan-shaped medium-deep hole drilling is greatly improved, and the preparation time for the medium-deep hole stope is getting shorter and shorter. At the same time, the medium-deep hole has a large amount of blasting, the production capacity of the stope is large, and the production cost is low. . Therefore, the medium and deep hole mining is increasingly favored by major mines. However, the diameter of the blasthole in the middle-deep hole ore is large, the parameters of the hole network are complex, and the parameters of rock drilling and blasting are relatively high. The reasonable rock blasting parameters have a significant effect on the process advantages, and the parameters of the medium-deep hole ore are reasonably optimized. It has always been the goal pursued by major mines. The main methods for obtaining reasonable rock drilling and blasting parameters are as follows [4-8]:
(1) Derivation of the blasting funnel test, using the Livingston blasting theory, according to the results of the field blasting funnel test, the blasting parameters under different blasthole diameters are derived;
(2) Derivation of empirical formula, according to the mine situation, using the empirical formula to directly obtain the blasting parameters;
(3) On-site test, according to experience, delineate the reasonable interval value of the parameters, and obtain reasonable parameters through field practice.
Dragon lead zinc ore employed in deep hole drilling segment falls between columns ore mining, mining method and field tests 514 -170 middle stope. Since the mine has not carried out the blasting funnel test for underground mining, and the one-step mining field adopts shallow hole recovery, the existing rock blasting parameters are empirical parameters accumulated in many years of practice. The mining method in the staged rock drilling stage is a new mining method introduced by the mine. This method has extremely high requirements on rock drilling and blasting parameters. The mine does not have experience in rock blasting field accumulation, and only reasonable blasting parameters can give the greatest advantage of this method. In view of this, through full investigation and discussion, it is decided to carry out the blasting funnel test to achieve the purpose of reducing the bulk rate and reducing the mining cost, and recommending reasonable rock drilling and blasting parameters for deep hole blasting in mines.
1 blasting funnel theory
According to C. W. Livingston blasting theory, in actual blasting, as long as the aspect ratio of the drug pack is not more than 7, it can be regarded as blasting of the spherical drug pack. With the continuous research and development of blasting theory, in recent years, some foreign researchers conducted field tests. The research shows that when the aspect ratio of the drug package is not more than 8-10, it can be regarded as a spherical drug package.
According to the blasting theory, when the column charge is produced on the mine site, the charge parameter is changed to the unit length charge q, and the blast similarity principle is still established, that is, the blast similarity relationship can be expressed by the dimension L-q1/2:
In the formula, Lx and Lb are the corresponding linear parameters of the blasthole, such as the resistance line or the bottom distance of the hole, m; qx, qb are the unit blasting charges of the cylindrical blasting prototype and the blasting model respectively, kg/ m.
2 blasting funnel test plan
2.1 Test procedure
According to the blasting funnel theory and the purpose of the mine test, the steps to determine the deep hole blasting parameters in the Panlong lead-zinc mine are as follows:
(1) Select a suitable position in the well and conduct a single-hole blasting funnel test to find the optimum embedding depth Lj and the optimal blasting funnel radius R when the charge is Q;
(2) Using the charge depth Lj obtained by the single-hole blasting funnel test, the porous same-stage blasting funnel test is carried out to find the optimal hole spacing a, and calculate the unit explosive consumption unit q under the experimental research conditions;
(3) Select the appropriate position in the well, perform single-hole inclined step blasting, measure the maximum distance between the blasthole opening position and the free surface, that is, the best resistance line W for blasting;
(4) According to the blasting theory, the parameters obtained in the above test are derived from the reasonable parameters of deep hole blasting in the mine.
2.2 Test location
The selection of the test site is based on the principle of similarity to the ore rock in the stope, and it is selected as much as possible in the ore body close to the stope. Through on-site comprehensive comparison, it is determined that in the -170m middle section 520 and 522 ore mining stope. The test tunnel and test blasthole arrangement are shown in Figure 1.
2.3 rock drilling
The hole spacing of the post-filling and filling method is Φ60mm. Considering the operability of the test, the blasting funnel test hole diameter is Φ40mm, that is, the 7655 drill machine is equipped with Φ38mm bit drilling.
In the single hole blasting funnel test, it should ensure that the formation of adjacent blasting hoppers is not affected. According to the experience of similar mine blasting funnel test, the adjacent blasthole spacing is designed to be greater than 1.5m, two sets of blastholes, each set of 9 blastholes. The depths are: 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.80, 0.90 m.
After the single-hole blasting funnel test was completed, the porous same-stage blasting funnel test was carried out. The drilling depth is the best depth of the material obtained by the single-hole blasting funnel test. Two groups of blastholes are arranged, and each group has 7 blastholes. The design is 1.5R, 1.75R, 2.0R, 2.25R. Porous in-situ blasting was performed with the hole spacing of 2.5R and 2.75R.
The inclined step blasting test is carried out at the appropriate position of the roadway. The depth of the blasthole is 1.8m and the angle is between 40° and 50°. It ensures that the slope resistance line changes within the range of 0.3~1.1m. The blasthole angle can be drilled according to the site. The conditions are appropriately changed and two blastholes are arranged.
2.4 Charge, blasting
The blasting funnel test uses the 2# rock emulsion explosive used in the mine. Before the test, the test roll was measured. The diameter of the roll was 32mm, the length of the roll was 220mm, and the weight of the roll was 200g/vol.
Single funnel blasting test and porous same-stage blasting crater test 2 volumes per hole, on-site charge measurement, the actual drug package length-to-diameter ratio is about 8.33 ~ 9.7, can be regarded as spherical drug pack.
The blasting uses the detonator at the bottom of the detonating tube to detonate. When the single hole blasting crater is tested, multiple blastholes can be blasted at one time to ensure no effect between the blasting blastholes. When the porous blasting crater is tested, the same section is used. The bottom of the detonator tube detonator is detonated once.
3 test results analysis and parameter recommendation
3.1 single hole blasting funnel test
The single-hole blasting funnel test blasthole numbers are 11#～19# and 21#～29#, respectively. Among them, the 26# hole is broken by the surrounding blasthole blasting, the rock around the blasthole is broken, the blasthole is blocked, and the charge is not applied. The results of the remaining blasthole tests are shown in Table 1.
Using the principle of least squares method, the data obtained from the test is subjected to three-term regression, and the multi-expression expression of the test result, the blasting funnel volume V-drug center depth l and the blasting funnel radius R-the drug packet center depth l is obtained as follows:
Where: V———the volume of a single hole blasting funnel under test conditions, m3;
R———the radius of a single hole blasting funnel under test conditions, m;
l———The depth of the center of the drug pack under the test conditions, m.
According to the test result data, the characteristic curve diagram between V-l and R-l is made, as shown in Fig. 2 and Fig. 3 respectively.
The least squares method is used to solve the extreme values ​​of the cubic functions V-l and R-l. The optimal blasting parameters of the single-hole blasting funnel under the test conditions are as follows:
The optimal depth of the drug pack center is lj=0.45m; the best blasting funnel volume Vj=0.05003m3≈0.050m3; the best blasting funnel radius Rj=0.507m.
3.2 Porous same section blasting funnel test
The porous same-stage blasting crater test was carried out in the mining roadway of the Dongtou stop in the -170m horizontal 522 ore block with a hole depth of 0.60m and a buried depth of 0.45m. The first group of blastholes was numbered 31#~37. #, The second group of blasthole numbers is 41#~47#.
After blasting, the shape and volume of the blasting funnel between the blastholes were measured. At the same time, the blasting funnel was photographed in front, and the blasting funnel profile is shown in Fig. 4.
According to the porous same-stage blasting funnel test, the radius of the groove is about 0.57m in the direction of the vertical blasthole connection, and the groove depth is smaller than the depth of the center of the drug pack, similar to the single-hole blasting funnel test. There is no obvious inter-hole spine between 1#～2# hole, 2#～3# hole and 3#～4# hole. There are obvious inter-hole spines between the 34#~35# holes and the 44#～45# holes. The fracture degree of the multi-hole blasting test is better than that of the single-hole blasting funnel, and the volume of the blasting funnel is also increased.
According to the above blasting results, under the test conditions, the optimal hole bottom distance of Panlong Mine is about 2 times of the optimal funnel radius, that is, 1.0 to 1.2 m, and the explosive unit consumption is 0.456 kg/t.
3.3 Inclined Bench Blasting Test The inclined bench blasting test is carried out in a tilting blasthole test in the -170m horizontal 520 ore bottom roadway. A total of 2 blastholes are blasted. The test results and results are shown in Table 2.
It can be seen from the scene blasting situation that the blasting of the two groups of blastholes is uniform and the bulk rate is low. Take the average value of the minimum resistance line in Table 2. Under the test conditions, the maximum resistance line is 0.79m.
3.4 Recommended blasting parameters
The minimum resistance line obtained by the blasting test of the inclined step, the charge per meter, and the hole bottom distance parameter obtained by the multi-hole blasting crater test are substituted into the theoretical formula of the blasting funnel to obtain the minimum resistance line and the bottom of the blasting of the Panlong Mine. Distance, see Table 3.
4 Conclusion
(1) The single-hole blasting funnel test, the multi-hole blasting crater test and the inclined step blasting test were carried out in the mine-170m middle section. The optimum blasting funnel volume and the best burial depth were obtained under the test conditions. Explosive unit consumption, optimum hole spacing and minimum resistance line.
(2) According to the Livingston blasting theory, combined with the results of the blasting funnel test, the deep hole blasting parameters in the mine were deduced: the aperture is 60mm, the minimum resistance line is 1.36m, and the hole bottom distance is 1.72~2.05.
(3) The test site of the blasting funnel is basically the same as that of the stope. The test procedure and test method are scientific, and the test results are reasonable. It can be used as the rock blasting parameter for deep hole blasting in mines.
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Luo Jia ; Changsha Mining Research Institute Co., Ltd., Changsha 410012, China; National Metal Mining Engineering Technology Research Center, Changsha 410012, China;
Wang Lihong; Changsha Mining Research Institute Co., Ltd., Changsha 410012, China;
Source: Mining Technology: 2016, 16(3);
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