A method for detecting large block rate in open-pit deep hole step blasting

Abstract

The present invention discloses a method for detecting the bulk rate of open-pit deep hole step blasting, and the method comprises the following steps: according to the engineering geological conditions of the open-pit step ore body and the technical parameters of the step blasting, numerical simulation calculation is performed on the blasting of the open-pit step ore body, and the location of the generation of bulk ore and rock on the open-pit step ore body after blasting is determined according to the calculation result; step blasting is carried out according to the blasting design parameters, and during the step blasting process, a high-speed camera is used to shoot and record the blasting process in the direction of the location of the generation of bulk ore and rock determined according to the simulation calculation, and then the blasting record photographic data is analyzed to confirm the location and throwing location of the bulk ore and rock; according to the confirmed throwing location of the bulk ore and rock, the bulk ore and rock are counted on site, and the bulk rate is obtained according to the volume ratio of the bulk ore and rock to the step rock body. The present invention can take into account both the detection efficiency of the bulk rate of step blasting and the accuracy of the detection result.

Description

Technical Field

[0001] The invention relates to the technical field of open-pit deep hole step blasting, and in particular to a method for detecting large block rate of open-pit deep hole step blasting. Background Art

[0002] The step blasting technology has the characteristics of simple construction and low cost, and is widely used in open-pit mining projects. The step blasting effect directly affects the mining efficiency of the mine. The large block rate is an important indicator for evaluating the step blasting effect. If the large block rate is too large, it will be inconvenient for shoveling and transportation, thereby increasing the cost of secondary crushing. If the large block rate is low, the cost of drilling and charging in the early stage will increase. Therefore, accurate and convenient statistics of the large block rate of ore and rock are of great significance to improving production efficiency and reducing production costs.

[0003] At present, there are several main methods for counting the block size of blasted ore and rock in engineering practice: first, direct measurement on the surface of the blast pile after step blasting. This method has high measurement accuracy, but low work efficiency and even affects normal production work; second, plane photography of the blast pile surface, through digital image processing software processing and analysis, this method has high work efficiency, but also has high requirements for photography technology and low accuracy; third, after mining and loading, count the number of ore and rock that are inconvenient to shovel, this method is simple to operate, but the counting is relatively rough. The above methods have the defect that it is difficult to take into account both the efficiency of large block rate detection and the accuracy of detection results. Summary of the invention

[0004] In order to solve the above problems, an embodiment of the present invention provides a method for detecting large block rate of open-pit deep hole step blasting, which specifically includes the following steps:

[0005] Step S1: According to the engineering geological conditions of the open-pit bench ore body and the technical parameters of bench blasting, numerical simulation calculation is performed on the blasting of the open-pit bench ore body, and the location of the generation of large ore rocks on the open-pit bench ore body after blasting is determined according to the calculation results;

[0006] Step S2: carrying out step blasting according to the blasting design parameters, using a high-speed camera to record the blasting process in the direction of the location where the large pieces of ore and rock are generated according to the simulation calculation, and then analyzing the blasting record photography data to confirm the location where the large pieces of ore and rock are generated and thrown;

[0007] Step S3: according to the confirmed throwing position of the large ore and rock blocks, the large ore and rock blocks are counted on site, and the large block rate is obtained according to the volume ratio of the large ore and rock blocks to the step rock mass.

[0008] Preferably, step S1 comprises the following steps:

[0009] Step S11: Detailed investigation of engineering geological conditions of open-pit steps;

[0010] Step S12: conducting a small-charge test explosion test on the step ore body and monitoring blasting vibration; establishing a step blasting dynamic finite element numerical model using finite element analysis software according to the step blasting technical parameters and engineering geological conditions;

[0011] Step S13: Substituting the empirical parameters of rock mass physics and mechanics as initial values ​​into the numerical model for calculation, and obtaining a numerically calculated blasting vibration time history curve;

[0012] Step S14: Calculate the blasting vibration data error between the on-site monitoring and the numerical model at the same point;

[0013] If the calculation error between the blasting vibration data at the same point in the on-site monitoring and the numerical model is less than 10%, the initial rock mass physical and mechanical parameters are suitable for the site, and step S15 is executed;

[0014] Otherwise, the physical and mechanical parameters of the rock mass are adjusted step by step based on the initial values, and the process returns to step S13;

[0015] Step S15: Check the numerical calculation results, export the numerical calculation effect diagram of the step blasting, and preliminarily analyze the location where the large pieces of ore and rock are generated after the blasting.

[0016] Preferably, the step S11 includes obtaining the geometric dimensions and lithology of the stepped ore body.

[0017] Preferably, the blasting technical parameters include hole network parameters and charge parameters.

[0018] Preferably, the empirical parameters of rock mass physical mechanics include: density, elastic modulus, Poisson's ratio, yield strength, tangent modulus, and hardening coefficient.

[0019] Preferably, the blasting vibration data error refers to the error between the blasting vibration velocity peak value and the main frequency.

[0020] Preferably, step S15 comprises the following steps:

[0021] S151: The damage variable value defined in the rock blasting damage model in numerical simulation is D = 1- , where D is the rock damage variable and Cd is the rock crack density; the numerical calculation results can be used to view the value of the damage variable D of the unit, and the damage variable value Dc of the ore rock in the critical crushing state can be selected based on engineering experience;

[0022] S152: Set the initial block diameter R0 according to the development of the original joints and fractures of the ore and rock; select a typical cross-section of the model and divide the cross-section of the bench ore body model into square grids with a length * width of R0 * R0. Statistically analyze the distribution of the damage variable value D in each grid area, and judge the magnitude relationship between the damage variable value D in each grid area and the damage variable value Dc of the rock mass in the critical fracture state. If D > Dc, the bench ore body fractures in this grid area; if D < Dc, the bench ore body does not fracture in this grid area. Statistically analyze the length L of the ore and rock in the unbroken part of the cross-section of the bench ore body model, and judge the magnitude relationship between the length L of the ore and rock in the unbroken part and the set large block size L0. If L > L0, judge that the ore and rock in the unbroken part is a large block, and obtain the generation position of the large block.

[0023] Preferably, the initial block size of the bench rock mass is determined according to engineering surveys.

[0024] Preferably, multiple typical cross-sections of the model should be selected evenly at equal distances, and the damage variable value Dc of the rock mass in the critical fracture state is determined according to the lithology.

[0025] Preferably, the high-speed cameras are arranged at positions on the side and front of the bench that are greater than the safety warning line.

[0026] Compared with the prior art, the beneficial effects of the present invention include: By performing numerical simulation calculations on the blasting of open-pit bench ore bodies, the generation positions of large ore and rock blocks on the open-pit bench ore bodies after blasting can be predicted. Cameras can be accurately arranged in key areas to determine the generation positions and throwing positions of large blocks, with high accuracy. Then, manually and directionally count the large ore and rock blocks in bench blasting, which can improve the detection efficiency. Therefore, this method can balance the detection efficiency and the accuracy of the detection results of the large block rate in bench blasting. Description of the Drawings

[0027] Figure 1 is the flow chart of the detection method of the present invention;

[0028] Figure 2 is the on-site trial blasting vibration test chart of the present invention;

[0029] Figure 3 is the on-site trial blasting numerical model established by the present invention;

[0030] Figure 4 is the damage distribution nephogram of the bench blasting rock mass of the present invention;

[0031] Figure 5 is the schematic diagram for numerically simulating and confirming the position of large rock blocks;

[0032] Figure 6 is the throwing position of the blasting rock mass recorded by the high-speed photography instrument;

[0033] Figure 7 It is the cumulative distribution curve of rock size obtained after accurately locating large blocks of mineral rock. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] Example 1

[0036] The present invention provides a method for detecting the bulk rate of open-pit deep hole step blasting. Figure 1 , the method of the present invention comprises the following steps:

[0037] S1: According to the engineering geological conditions of the open-pit bench ore body and the technical parameters of bench blasting, the blasting of the open-pit bench ore body is numerically simulated and calculated, and the location of the large block of ore rock on the open-pit bench ore body after blasting is determined according to the calculation results.

[0038] Specifically, the steps include:

[0039] S11: Detailed investigation of engineering geological conditions of the open-pit steps. Preferably, the geometric dimensions and lithology of the step ore bodies are obtained, and the geometric dimensions include the length, width, height, inclination, and dip angle of the steps.

[0040] S12: Carry out small-charge test explosion on the bench ore body and monitor blasting vibration. The measurement point arrangement is referenced Figure 2 , three test explosion monitoring points C1, C2 and C3 were arranged at intervals on one side of the explosion source E; according to the technical parameters of the step blasting and the engineering geological conditions, the finite element numerical model of the step blasting dynamics was established using finite element analysis software, referring to Figure 3 , explosives 2 and taphole mud 1 are set at corresponding positions of the step ore body 3.

[0041] Preferably, the dynamic finite element software ANSYS / LSDYNA is used for numerical simulation, and the material used is the *MAT_JOHNSON_HOLMQUIST_CONCRETE material constitutive built into the software, which can simulate rock materials under large strain, high strain rate and high pressure. It should be understood that if the simulation method is appropriate, this method is also applicable to simulations using other software.

[0042] Specifically, the blasting technical parameters include hole network parameters and charge parameters.

[0043] S13: Substitute the empirical parameters of rock mass physics and mechanics into the numerical model as initial values ​​to obtain the numerical calculation blasting vibration time history curve.

[0044] Preferably, the physical and mechanical empirical parameters of the rock mass include: density, elastic modulus, Poisson's ratio, yield strength, tangent modulus, and hardening coefficient.

[0045] S14: Calculate the error of the blasting vibration data at the same point in the field monitoring and the numerical model. In this method, the error needs to be less than 10%;

[0046] If the calculation error of the blasting vibration data at the same point in the field monitoring and the numerical model is less than 10%, then the initial physical and mechanical parameters of the rock mass are applicable to this site, and step S15 is executed;

[0047] Otherwise, the physical and mechanical parameters of the rock mass are adjusted step by step on the basis of the initial value, and step S13 is executed again until the error between the field test value and the numerical calculation value is less than 10%. When adjusting, judge the adjustment range of the parameters according to the change trend of the error.

[0048] Preferably, the error of the blasting vibration data refers to the error between the peak value of the blasting vibration velocity and the main frequency.

[0049] S15: Check the numerical calculation results, export the numerical calculation effect diagram of bench blasting, and preliminarily analyze the position where large pieces of ore and rock are generated after blasting, such as Figure 4 shown.

[0050] Specifically, it includes the following steps:

[0051] S151: The value of the damage variable defined by the rock blasting damage model in the numerical simulation is D = 1 - , where D is the rock damage variable and Cd is the rock crack density; the numerical calculation results can be used to check the value of the damage variable D of the element. Combining with engineering experience, select the damage variable value Dc of the ore and rock in the critical crushing state.

[0052] S152: According to the original joint fissure development of the ore and rock, set the initial block size diameter R0; select a typical cross-section of the model and divide the cross-section of the bench ore body model into square grids with a length * width of R0 * R0. Count the distribution of the damage variable value D in each grid area, and judge the size relationship between the damage variable value D in each grid area and the damage variable value Dc of the rock mass in the critical crushing state. If D > Dc, the bench ore body will fracture and break in this grid area. If D < Dc, the bench ore body will not fracture in this grid area; count the length L of the ore and rock in the unbroken part of the cross-section of the bench ore body model, and judge the size relationship between the length L of the ore and rock in the unbroken part and the set large block size L0. If L > L0, judge that the ore and rock in the unbroken part is a large block, and obtain the position where the large block is generated, such as Figure 5 shown.

[0053] Preferably, the initial block size of the bench rock mass is obtained according to engineering exploration.

[0054] Preferably, multiple typical cross sections of the model should be selected evenly and at equal distances.

[0055] Preferably, the rock damage variable value Dc in the critical crushing state is taken according to the lithology.

[0056] S2: Carry out step blasting according to the blasting design parameters. During the step blasting, use a high-speed camera to shoot and record the blasting process in the direction of the location where the large pieces of ore and rock are generated according to the simulation calculation. Then analyze the blasting record photography data to confirm the location where the large pieces of ore and rock are generated and thrown, such as Figure 6 shown.

[0057] Preferably, the high-speed camera is arranged at a position on the side and front of the steps that is larger than the safety warning line.

[0058] S3: According to the confirmed throwing position of the large ore and rock blocks, the large ore and rock blocks are counted on site, and the large block rate is obtained according to the volume ratio of the large ore and rock blocks to the step rock mass. The cumulative distribution curve of the ore and rock block size is obtained by statistics, such as Figure 7 shown.

[0059] The present invention can predict the location of large blocks of ore and rock on the open-pit step ore body after blasting by performing numerical simulation calculations on the blasting of the open-pit step ore body, and can accurately arrange cameras in key areas to determine the location of the generation and throwing of large blocks with high accuracy. The large blocks of ore and rock produced by step blasting can be counted manually in a directional manner to improve the detection efficiency. Therefore, the present method can take into account both the detection efficiency of the step blasting large block rate and the accuracy of the detection results.

[0060] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for detecting the bulk rate of open-pit deep hole step blasting, characterized in that: Including the following steps: Step S1: According to the engineering geological conditions of the open-pit bench ore body and the bench blasting technical parameters, conduct numerical simulation calculations on the blasting of the open-pit bench ore body, and determine the generation positions of large pieces of ore and rock on the open-pit bench ore body after blasting according to the calculation results; Step S2: Carry out bench blasting according to the blasting design parameters. During the bench blasting process, use a high-speed camera to take pictures and record the blasting process in the direction of the generation position of large pieces of ore and rock determined by the simulation calculation. Subsequently, analyze the blasting record photographic materials to confirm the generation positions and throwing positions of the large pieces of ore and rock; Step S3: According to the confirmed throwing positions of the large pieces of ore and rock, conduct on-site shoveling and loading to count the large pieces of ore and rock, and obtain the large-piece rate according to the volume ratio of the large pieces of ore and rock to the bench rock mass.

2. The method for detecting large block rate in open-pit deep hole step blasting according to claim 1, characterized in that: The said Step S1 includes the following steps: Step S11: Conduct a detailed investigation of the engineering geological conditions of the open-pit bench; Step S12: Carry out a small-charge trial blasting test on the bench ore body and conduct blasting vibration monitoring; according to the bench blasting technical parameters and engineering geological conditions, establish a bench blasting dynamic finite element numerical model using finite element analysis software; Step S13: Substitute the physical and mechanical empirical parameters of the rock mass as the initial values into the numerical model for calculation to obtain the numerical calculation blasting vibration time history curve; Step S14: Calculate the blasting vibration data error at the same point positions in the on-site monitoring and the numerical model; If the calculation error of the blasting vibration data at the same point positions in the on-site monitoring and the numerical model is less than 10%, the initial physical and mechanical parameters of the rock mass are applicable to this site, and Step S15 is executed; Otherwise, gradually adjust the physical and mechanical parameters of the rock mass on the basis of the initial values, and return to execute Step S13; Step S15: Check the numerical calculation results, export the numerical calculation effect diagram of bench blasting, and preliminarily analyze the generation positions of large pieces of ore and rock after blasting.

3. The method for detecting large block rate in open-pit deep hole step blasting according to claim 2, characterized in that: The said Step S11 includes obtaining the geometric dimensions and lithology of the bench ore body.

4. The method for detecting large block rate in open-pit deep hole step blasting according to claim 2, characterized in that: The said blasting technical parameters include hole pattern parameters and charging parameters.

5. The method for detecting large block rate in open-pit deep hole step blasting according to claim 2, characterized in that: The said physical and mechanical empirical parameters of the rock mass include: density, elastic modulus, Poisson's ratio, yield strength, tangent modulus, hardening coefficient.

6. The method for detecting large block rate in open-pit deep hole step blasting according to claim 2, characterized in that: The said blasting vibration data error refers to the error between the peak value of the blasting vibration velocity and the main frequency.

7. The method for detecting large block rate in open-pit deep hole step blasting according to claim 2, characterized in that: The said Step S15 includes the following steps: S151: The damage variable value defined in the rock blasting damage model in numerical simulation is Where D is the rock damage variable, C d is the rock crack density; the numerical calculation results can be used to check the damage variable D value of the unit, and the damage variable value Dc of the ore rock in the critical crushing state can be selected based on engineering experience; S152: According to the original joint fissure development situation of the ore and rock, set the initial block diameter R0; select a typical cross-section of the model and divide the cross-section of the bench ore body model into square grids according to the length * width of R0*R0, count the distribution of the damage variable value D in each grid area, and judge the size relationship between the damage variable value D in each grid area and the rock mass damage variable value Dc in the critical fracture state. If D>Dc, the bench ore body fractures and breaks in this grid area; if D<Dc, the bench ore body does not fracture in this grid area; count the length L of the ore and rock in the unbroken part of the cross-section of the bench ore body model, and judge the size relationship between the length L of the ore and rock in the unbroken part and the set large-piece size L0. If L>L0, judge that the ore and rock in the unbroken part is a large piece, and obtain the large-piece generation position.

8. The method for detecting large block rate in open-pit deep hole step blasting according to claim 7, characterized in that: The initial block size of the bench rock mass is obtained according to the engineering investigation.

9. The method for detecting large block rate in open-pit deep hole step blasting according to claim 7, characterized in that: The selection of typical cross sections of the model should be uniformly selected at equal distances, and the value of the rock damage variable Dc in the critical crushing state should be determined according to the lithology.

10. The method for detecting large block rate in open-pit deep hole step blasting according to claim 1, characterized in that: High-speed cameras are placed on the sides and front of the steps at a position larger than the safety warning line.

Images