Focus on mining, oil and water well mining and excavation
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By peter | 26 June 2024 | 0 Comments

CO2 rock blasting VS explosive blasting

Mining is dangerous, so blasting can only be carried out after a strict approval process. Some mining areas are close to buildings, so when blasting, not only large blocks and foundation phenomena should be considered, but also vibration, flying rocks and dust phenomena should be avoided as much as possible to avoid the impact on surrounding buildings and residents. In the traditional mining blasting process, explosive blasting is the most commonly used.
Explosive blasting is powerful and highly destructive to rocks. It can effectively meet the blasting requirements, but there are great safety hazards. Therefore, the approval procedure for explosives is relatively complicated. In order to solve this problem, a relatively new form of blasting has emerged in society, namely carbon dioxide blasting.

The carbon dioxide fracturing device uses the physical principle that liquid carbon dioxide absorbs heat and expands, and the pressure rises rapidly. It consists of a steel pipe filled with liquid carbon dioxide, an activator, an energy discharge component, an inflating component, an ignition circuit connection component, and other connection auxiliary components. Liquid carbon dioxide is instantly gasified by heating in an activator, releasing high-pressure gas energy to break target materials such as rocks, coal seams, and concrete. It solves the shortcomings of previous explosive blasting and pre-splitting, such as high destructiveness, high danger, and ore body crushing, and provides reliable guarantees for safe mining and pre-splitting in mines.
Comparison of advantages and disadvantages of explosive blasting and carbon dioxide blasting
Explosive blasting
1. Strong power and significant crushing effect;
2. Relatively low blasting cost;
3. Simple blasting process and high blasting efficiency
1. High risk factor and difficult approval;
2. High destructiveness, easy to affect surrounding buildings and residents;
3. Strong crushing, resulting in reduced utilization of stone;
4. Serious noise and dust pollution, not environmentally friendly.
Carbon dioxide blasting
1. No strict approval is required, easy to use;
2. Low noise, reducing the impact on surrounding residents;
3. Environmental protection, reducing environmental pollution;
4. Reduce the risk factor and high safety;
5. Avoid ore body crushing and improve stone utilization;
6. Some devices can be reused.
1. The steps are too complicated and inefficient;
2. It is not suitable for deep foundation pits or working surfaces with poor volleying;
3. It is impossible to achieve multi-row blasting, and the output is low;
4. The activator used is a disposable item with high cost;
5. The blasting tube filling process and on-site construction are relatively complicated, and the quality requirements of the blastholes are relatively high.
Although carbon dioxide blasting can make up for the problem of difficult approval of explosive blasting, it is still difficult to replace the position of traditional explosive blasting in a short time because the blasting power is weaker than that of explosives and the cost is high. The following mainly analyzes how to optimize the parameters of traditional explosive blasting and reduce the cost of blasting.
Optimize explosive blasting parameters to reduce blasting costs
The complete process of open-pit mining consists of drilling, blasting, shoveling, transportation and crushing, among which the cost of drilling and blasting accounts for about 20% of the total cost of the entire mining process. Therefore, it is necessary to choose a suitable blasting scheme to effectively reduce the mining cost of the mine. To reduce the blasting cost, it is usually necessary to optimize the blasting parameters through the following links.
1. Geological survey
The level of detail of geological survey has a significant impact on the blasting effect. Before blasting, a professional team can be invited to conduct photogrammetry of the rock mass on the slope of the mine steps to obtain digital images of the macroscopic structure of the rock mass, and use certain technologies to analyze the hardness and integrity of the rock.
2. Calculate the blasting cost
Based on the current blasting parameters of the mine, the blasting effect is quantitatively evaluated by statistically analyzing the blasting large block rate, and the relationship between the main blasting parameters and the large block rate is calculated, and then the blasting cost is analyzed. The large block rate will not only affect the blasting cost, but also the shoveling cost, transportation cost and secondary crushing cost. The second is to optimize the blasting parameters and find the best blasting solution.
3. Optimize blasting parameters
Open-pit mine blasting generally requires concentrated blasting piles after blasting, uniform block size, and control of large block rate. Combined with these requirements, and considering the reduction of blasting costs, it is generally necessary to start with the step height, filling height, charge length, charge structure and detonation method, delay time, detonation network and other parameters for optimization.
(1) Step height
The step height is mainly calculated by the diameter of the blasthole. At the same time, for mines with a certain mining depth, when the step height is small, the unit consumption of explosives can be reduced, but the number of steps, the total length of perforation and the consumption of blasting equipment will increase. However, in general, the cost of perforation blasting will be reduced. Therefore, the step height of the mine can be reduced to a reasonable height as much as possible according to the actual situation and annual output of the mine.
(2) Filling length and charging length
During the blasting process of the mine, when joints and fissures are developed, increasing the spacing between blastholes can achieve better blasting effects. In order to make full use of the perforation length, in addition to meeting the filling length requirements, the remaining length of each blasthole is used for charging.
(3) Charge structure and detonation method
In order to enhance the blasting effect and meet the blasting block size requirements, the charge structure can adopt a columnar continuous charge structure, and the detonation method adopts a detonating cord detonator detonation. For explosives without detonator sensitivity, detonating bombs can be used for detonation. Insert the detonator into the detonating bomb and ensure that the energy-gathering hole of the detonator faces upward to detonate the explosive.
(4) Delay time
There is a general empirical formula for calculating the delay time, that is, △t=kB, where B is the resistance line and k is the delay coefficient. The value range of k is 3-8. The smaller value is used for hard rock and the larger value is used for soft rock. The specific value should be determined based on the survey of the mine. In general, the delay time is 65ms.
(5) Detonation network
Micro-difference blasting can effectively control blasting shock waves, vibrations, noise and flying rocks. It is simple, safe and quick to operate. It can be blasted close to the fire without causing damage. The degree of fragmentation is good, which can improve the blasting efficiency and technical and economic benefits. When using micro-difference blasting, the blasting network can be laid using a V-shaped or oblique blasting network.
In order to formulate a suitable blasting plan to reduce blasting costs and meet blasting requirements, we can use cost as the objective function to optimize blasting parameters and improve the production efficiency and economic benefits of the mine.
Construction safety precautions
1. Strictly follow the design requirements for construction
2. Ensure filling quality and density
3. Strengthen sentry guards at intersections and key roads
4. Evacuate equipment and personnel to the blasting safety zone before blasting
5. Detonators must enter the bunker to strengthen their own safety
CO2 rock blasting

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