In mining, the ore should be exfoliated from the rock mass by mining blasting and the surrounding rock of the ore body roof should be stripped, and blasted into a certain explosive pile according to the engineering requirements, and broken into a certain block degree for the subsequent shovel loading, Transport work creates conditions. The mine blasting technology has developed rapidly with the construction of the mine project. Different blasting methods have a great impact on the mining cost. In the whole process of mining, the cost of piercing blasting accounts for about 20% of the total cost. Selecting a specific blasting method based on the rock structure of the mine can not only improve the blasting effect, but also save mining costs.
Mining has certain dangers, so it can be carried out after rigorous approval procedures. Some mining areas are close to the building. Therefore, not only the bulk and bottom phenomena should be considered during blasting, but also vibration should be avoided. The impact of flying stones and dust on surrounding buildings and residents. In the traditional mine blasting process, the most used is explosive blasting. Explosive blasting has great power and is highly destructive to rocks. It can effectively meet the blasting requirements, but there are great safety hazards. Therefore, the approval procedure for explosives is complicated, in order to solve This kind of problem, there is now a relatively new form of blasting in the society, namely carbon dioxide blasting.
Carbon dioxide blasting
The carbon dioxide cracker utilizes 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, a bleeder assembly, an inflatable component, an ignition circuit connection component, and other connection auxiliary components. Activator by heating instantaneously vaporized liquid carbon dioxide, releasing high pressure gas energy, fractured rock, coal layer of target material, concrete and the like. It solves the shortcomings of blasting mining and pre-cracking in the past, which is highly destructive, high-risk, and toxic in the ore body, which provides a reliable guarantee for safe mining and pre-cracking of mines.
Comparison of advantages and disadvantages between explosive blasting and carbon dioxide blasting
Explosive blasting
Advantages: 1. High power and remarkable crushing effect; 2. Relatively low blasting cost; 3. Simple blasting process and high blasting efficiency
Disadvantages: 1. High risk coefficient, difficult to approve; 2. Greatly destructive, easy to affect surrounding buildings and residents; 3. Strong pulverization, resulting in reduced utilization of stone materials; 4. Noise and dust pollution is serious, no Environmental protection.
Carbon dioxide blasting
Advantages: 1, no strict approval, easy to use; 2, low noise, reduce the impact on surrounding residents; 3, environmental protection, reduce environmental pollution; 4, reduce the risk factor, high security; 5, avoid ore body crushing, improve Stone utilization rate; 6, some devices can be reused.
Disadvantages: 1, the steps are too cumbersome, low efficiency; 2, deep foundation pit or volley bad working surface is not suitable; 3, can not achieve multiple rows of blasting, low output; 4, the use of activators is disposable, high cost 5, the blasting drum filling process and on-site construction are more complicated, and the quality of the blasthole is relatively high.
Although carbon dioxide blasting can make up for the difficulty of explosive approval of explosives, but because the blasting power is weaker than explosives and the cost is high, it is still difficult to replace the traditional explosive blasting status in a short time. Next, it mainly analyzes how to optimize the traditional explosive blasting. The parameters reduce the cost of blasting.
Optimize explosive blasting parameters and reduce blasting costs
The complete process of open pit mining consists of perforation, blasting, shovel loading, transportation and crushing. The cost of perforation 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. In order to reduce the cost of blasting, it is usually necessary to optimize the blasting parameters through the following steps.
1. Geological survey
The level of detail of the geological survey has a significant impact on the blasting effect. Before blasting, a professional team can be used to perform photogrammetry on the rock mass of the slope of the mine, obtain a digital image of the macroscopic structure of the rock mass, and analyze the rock with a certain technique. Hardness and completeness.
2. Calculate the cost of explosion
According to the current blasting parameters of the mine, the blasting effect is quantitatively evaluated by statistical blasting bulk rate, and the relationship between the main blasting parameters and the bulk rate is calculated, and then the blasting cost is analyzed. The bulk rate will not only affect the cost of blasting, but also the cost of shovel loading, transportation costs and secondary crushing costs. The second is to optimize the blasting parameters to find the best blasting plan.
3. Optimize the blasting parameters
Open-pit mine blasting generally requires blasting after blasting, uniform block size, and control of large block rate. Combined with these requirements, and then consider reducing the cost of blasting, generally from step height, packing height, charge length, charge structure and detonation Methods such as method, delay time, and detonation network are used to optimize.
(1) step height
The height of the step is mainly calculated by the diameter of the blasthole. At the same time, for mines with a certain mining depth, when the height of the step is small, the unit consumption of the explosive can be reduced, but the number of steps, the total length of the perforation and the consumption of the detonating equipment are increased, but Generally speaking, the cost of perforation blasting will be reduced. Therefore, the height of the step of the mine can be reduced to a reasonable height according to the actual situation of the mine and the annual output.
(2) Packing length and charge length
In the process of mine blasting, when the joint fissures are developed, the blasting effect can be obtained by increasing the blasthole spacing. In order to make full use of the perforation length, each blasthole is used for charging except for the requirement of the tamping length.
(3) Charge structure and detonation method
In order to strengthen the blasting effect and achieve the block requirement of blasting, the charging structure can adopt the columnar continuous charging structure, and the detonating method adopts the detonating tube detonator to detonate. For the explosive without the detonator sensitivity, the detonating bomb can be used for detonation, and the detonator is inserted into the detonating bomb. Inside, ensure that the detonator's gathering energy points face up to detonate the explosive.
(4) Delay time
The calculation of delay time has a general empirical formula, namely â–³t=kB, where B is the resistance line, k is the delay coefficient, the value interval of k is 3-8, the hard rock takes a small value, and the soft rock takes a large value. The value should be determined based on the survey of the mine. In general, the delay time is 65ms.
(5) Detonation network
Millisecond blasting can effectively control blasting shock waves, vibrations, noise and flying stones. It is easy to operate, safe and fast, and can be fired near fire without causing damage. The degree of crushing is good, which can improve the blasting efficiency and technical and economic benefits. When using millisecond blasting, the detonation network can be laid with a V-shaped or slashed detonation network.
In order to develop a suitable blasting scheme to reduce the blasting cost and meet the blasting requirements, we can use the cost as the objective function to optimize the blasting parameters and improve the mine production efficiency and economic benefits.
Construction safety precautions
1. Construction in strict accordance with design requirements
2, to ensure filling quality and density
3. Strengthen the intersection of all roads and the guards of all key roads.
4. Evacuate equipment and personnel to the blasting safety zone before blasting
5, the detonator should enter the bunker to strengthen their own safety
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