(1) Unified ventilation and partition ventilation
A mine consists of a single ventilation system called unified ventilation; it is divided into several independent ventilation systems, and the airflow does not interfere with each other, called zone ventilation. When developing a mine ventilation system, first consider whether to use uniform ventilation or district ventilation.
Our metal mine ventilation more uniform. Uniform ventilation, concentrated air intake and exhaust, easy to manage. Mines with a small mining area, especially deep mines, are more reasonable to use uniform ventilation throughout the mine.
Partition ventilation has the characteristics of short circuit, low resistance, simple network and easy control of wind flow. Therefore, it has been widely used in some mines where shallow or scattered mines or mines are used to mine shallow ore bodies. However, since the district ventilation needs to have more air intake and exhaust wells, its promotion and use are subject to certain restrictions.
Whether it is suitable for district ventilation, mainly depends on the amount of ventilation shafts that can be used to cut through the surface or the availability of other wells. Generally speaking, under the following conditions, it is more advantageous to use district ventilation: the ore body is buried shallowly and scattered, the ventilation shaft of the ground surface is small, or there are ready-made wells available for use; the ore body is buried shallowly. If it is long, the output is large. If it forms a ventilation system, the wind path is long, the air leakage is large, the network is complicated, and the air volume adjustment is difficult; the mining of surrounding rock or ore has a large-scale mine with natural fire hazard.
(2) Layout of intake and return wells
Each ventilation system has at least one reliable inlet and one reliable return well. Under normal circumstances, the tank cage lifting well is also used as the inlet shaft, and the bucket well and the bucket and cage mixing well are not used as the inlet well. This is because a large amount of dust generated during loading and unloading can cause pollution of the wind. Exhaust wells are usually dedicated because the exhaust air contains a lot of toxic gases and dust.
According to the relative position of the inlet and exhaust shafts, it can be divided into three types: central type, diagonal type and central diagonal type. The central type is that the inlet and exhaust shafts are located in the field. In the central part, the flow path of the wind flow in the downhole is a reentry type; the diagonal type is the wing of the intake shaft in the ore body, the exhaust shaft is in the other wing of the ore body, or the inlet well is in the center of the ore body, and the exhaust well is in the two wings, the wind flow The flow path in the underground is linear; the central diagonal mixing type, when the ore body is long, the mining area is wide, and the central type is used for development. The inlet and return wells can be arranged in the middle of the mine field to solve the mining of the central ore body. Ventilation at the same time; at the same time, the wind tunnel is drilled in the two wings of the mine to solve the ventilation during the mining of the remote ore body.
Due to the complicated conditions of the ore body, there are various ways of development and mining. In the mine design and production practice, it is necessary to combine the specific conditions of each mine, adapt to local conditions and use it flexibly, without being limited by the above categories.
(3) Main fan working mode and installation location
There are three main fan working modes: press-in, draw-out and press-pump. Different ways of ventilation, on the one hand, make the mine air under different pressure conditions, on the other hand, different forms of pressure distribution are formed on the entire ventilation line, so that the air volume, the wind quality and the degree of disturbance by natural wind flow, Different ventilation effects have occurred.
â—Push-in
The entire ventilation system forms a positive pressure above the local atmospheric pressure under the action of the push-in main fan. In the inlet section, due to the concentrated air volume, a higher pressure gradient is caused, and the external air leakage is larger. In the required wind section and the return air section, due to the large number of wind paths, the wind flow is dispersed and the pressure gradient is small, and the wind flow is reversed due to the disturbance of the natural wind flow. The air flow control facilities such as the damper of the press-in ventilation system are installed in the air inlet section. Due to frequent transportation and pedestrians, it is difficult to manage and the air leakage is large. The air inlet is ventilated by a dedicated air inlet, the wind flow is not polluted, the wind quality is good, and the main lifting shaft is in a return air state (leakage), which is beneficial to the anti-freezing of the winter lifting well in the cold area.
â—Extracted
The entire ventilation system forms a negative pressure state below the local atmospheric pressure under the action of the extracted main fan. In the return air section, the air volume is concentrated and there is a high pressure gradient; in the inlet and demand wind sections, the pressure gradient is small due to the dispersion of the wind flow. The pressure gradient in the return air section is high, so that the dirty airflow on the working surface is quickly concentrated to the return air passage, and the smoke dust is not easily diffused to other roadways, and the discharge speed is fast. In addition, since the wind flow control facilities are installed in the return air passage, it does not hinder transportation and pedestrians, and the management is convenient and the control is reliable. Withdrawn ventilation, the main lifting shaft is in the air inlet state, and the air flow is susceptible to pollution. Mines in cold regions should also consider freezing wells in winter. In general, it is advantageous to use draw-out ventilation as long as it can maintain a complete return air system so that it is not damaged during the mining process. Most of China's metal mines use draw-out ventilation.
â—Pumping and mixing
In the inlet and return sections, the main fan is used to control the wind flow, so that the whole ventilation system drives the wind flow along the designated route under the action of a high pressure gradient, so the smoke is fast, the air leakage is small, and it is not easily disturbed by the natural wind flow. Causes the wind to reverse. This kind of ventilation has the advantages of both the press-in type and the pull-out type of ventilation, which is an important way to improve the ventilation effect of the mine. Of course, the pumping and mixing ventilation requires more ventilation equipment and more complicated management.
â—Multi-stage station ventilation
This is a kind of several-stage inlet fan station to transfer fresh air to the working area through the inlet shaft through relay, and then the ventilation air formed by the several-stage return fan station is discharged into the mine through the return air shaft. system. The ventilation method is a pressure pumping hybrid. Because the system has fan fans in the air inlet section, the required wind section and the return air section, the whole system is subjected to pressure equalization ventilation, which can effectively control the air leakage, save ventilation energy consumption, and the air volume adjustment is also flexible. There are more ventilation equipment required and the management is more complicated.
The main fan can be installed on the surface or installed underground, and is usually installed on the surface. The main advantages of installation on the surface: installation, maintenance, maintenance management is more convenient; when a catastrophic accident occurs in the underground, the fan is not easily damaged, and it is convenient to take emergency measures such as stop wind, anti-wind or control air volume. The shortcomings are: wellhead sealing, anti-wind device and wind leakage; when the mine is deep and the working surface is far away from the main fan, the wind leakage is large along the way; in the case of complicated terrain conditions, the installation and construction costs are high. The main fan is installed underground: the main fan device has less air leakage; the fan fan is close to the working area, and there are less air leakage along the way; more air inlets or return air can be used to reduce the ventilation resistance; the amount of closed engineering is less. Its shortcomings: inconvenient installation, maintenance and management; easy to be destroyed by underground disasters.
Page 2 / (2 pages) (4) Stage ventilation, stop ventilation and ventilation structures
â— Stage ventilation
Metal mines usually operate simultaneously in multiple stages. In order to make the working surface of each stage get fresh air flow from the intake shaft and send the discharged sewage to the return air well, the wind flow of each working surface should not be connected in series, and it is necessary to enter and return to each stage. The wind tunnels are arranged in a unified manner to form a certain type of stage ventilation network. The stage ventilation network routing stage is formed by connecting the air inlet, the return air passage, the total return air passage of the mine and the concentrated return air patio.
â—Excavation ventilation
Reasonable stop ventilation network and ventilation method is the final link to ensure the effective ventilation of the entire ventilation system, and is an important part of the entire ventilation system. According to the structural characteristics of various mining methods, the ventilation of the mining face can be summarized as: ventilation of the roadway type or diversion type stope without mining level; ventilation of the stope with level of mining; Ventilation of the mining law.
â— Mine ventilation structure
The mine ventilation structure is a wind flow control facility in the mine ventilation system to ensure that the wind flow flows according to the production needs. The devices used to guide the wind flow, cover the wind flow and adjust the air volume are collectively referred to as ventilation structures. Properly installing ventilation structures and keeping them in good condition is an important task in the management of mine ventilation technology. Ventilation structures can be divided into two categories: one is the structure through the wind flow, including the main fan, the wind, the wind, the wind bridge, the wind deflector, the wind window and the wind barrier; the other is the structure that blocks the wind. Including windshield and damper.
(5) Air leakage and effective air volume of the ventilation system
â—Leakage location and cause of air leakage
In general, there is a leaky air passage, and when there is a pressure difference across the air leakage passage, air leakage can be generated. The main air leakage locations of metal mines and the causes of air leakage are as follows: Pull-out ventilated mines, through the surface subsidence area and the goaf directly leaking into the return air duct, sometimes reach a very high value. The reason for this air leakage is firstly due to the lack of overall arrangement on the mining, the formation of surface subsidence areas prematurely; the necessary isolation pillars are not retained in the upper part of the return airway; and also because the surface subsidence area and the goaf area are not Fill or segregate in time. Press-in ventilated mines also have high air leakage through the short circuit at the bottom of the well. This type of air leakage is often caused by the tightness of the damper at the bottom of the well and the complete failure of the damper. The working surface is scattered, and the waste roadway cannot be closed in time, resulting in wasted wind. Ventilation structures such as wellhead closures, anti-wind devices, downhole dampers, wind bridges, windshields, etc. are not tight, and can also cause large air leakage.
â— Reduce air leakage and improve effective air volume
Factors such as mine development, mining sequence, and mining methods have a great impact on mine leakage. Diagonal ventilation system, because the inlet and exhaust shafts are far apart, the wind flow is straight, the pressure difference is small, and the air leakage is smaller than the central side-by-side ventilation system. In the backward mining sequence, the goaf is developed from the two wings to the center, which is beneficial for reducing air leakage and preventing wind flow in series. Filling mining methods have less air leakage than other mining methods. In the layout of the roadway, the main transport lanes and ventilation tunnels are arranged outside the veins, so that they are not damaged prematurely during the mining process, which is beneficial to maintaining a normal ventilation system and reducing air leakage.
Pull-out ventilated mines should pay special attention to the air leakage in the surface subsidence area and the goaf. From the mining design and production management, it should be avoided to form the surface subsidence area too early, the mine that has formed the subsidence area, the pillar should be retained in the upper part of the return air passage, and the gob area or the closed patio opening should be filled. Press-in ventilated mines should take care to prevent air leakage from the intake yard. At least two reliable automatic dampers must be established between the intake and lift shafts. In some mines, wind tunnels or air curtains are used to guide the wind flow at the inlet and outlet of the roadway to prevent air leakage at the bottom of the well. Some mines use special wind inlets and alleys to cut through the air intake wells, avoiding the transportation system, and directly sending fresh air to each mining area, which can also reduce air leakage at the bottom of the well.
Improving the quality of ventilation structures and strengthening airtightness are the basic measures to prevent air leakage. The area of ​​the windshield and the damper should be as small as possible, and the concrete should be covered with concrete at the place where the wind wall is in contact with the rock wall. The door panel is preferably made of double-layered wood with a slick paper or other dense material. Iron door four weeks weld to be strict, the edge of the door frame to staple or linen rubber, the rubber damper curtain to hang below the set threshold and, holding tight.
Reducing wind resistance and balancing wind pressure are also important measures to reduce air leakage. The pressure difference between the two ends of the air leakage path is mainly determined by the ventilation resistance of the parallel wind location. Reduce the wind resistance at the wind location, reduce the pressure difference between the two ends, reduce the pressure difference between the two ends of the air leakage path, and reduce the air leakage. When selecting the air volume adjustment method, the resistance reduction method is more advantageous for reducing air leakage. The use of pressure pumping mixed ventilation and multi-stage station ventilation can make the mine wind pressure tend to balance and form a zero pressure zone in the production section, which is very beneficial to prevent air leakage and increase the effective air volume.
(6) Local ventilation
In mining and geological exploration projects, a large number of wells must be excavated, and the characteristics of these wells are only one outlet, so they are called single-head roadways. The ventilation of the single-head roadway is called local ventilation or tunneling. The task is to introduce fresh airflow to the working surface and discharge the dirty air such as gunpowder and dust from the working surface to ensure the workers work in a good environment.
â— Local ventilation method
Local ventilation methods include: local ventilation method using main fan (or auxiliary fan) wind pressure or natural wind pressure as power, referred to as total wind pressure ventilation; local ventilation method using diffusion, referred to as diffusion ventilation; using ejector ventilation The local ventilation method, referred to as the ejector ventilation; the local ventilation method using the local fan, referred to as the local fan ventilation.
In order to avoid circulating wind, local ventilation requirements: the amount of air drawn from the through-flow tunnel must not exceed 70% of the total air volume of the tunnel. When press-in ventilation, the suction port shall be located on the windward side of the wind tunnel, and the distance from the single head road crossing shall not be less than 10m; when the exhaust ventilation is used, the air outlet shall be located on the downwind side of the wind tunnel, and the distance from the single head roadway Not less than 10m. In the case of mixed ventilation, the exhaust vent of the extractable working fan shall also be located on the leeward side of the wind tunnel, not less than 10 m from the end of the single-head roadway, and the air volume at the suction port is required to be blown by the blow-in type fan. The amount is 20~25%; the distance between the suction type suction port and the extraction type suction port is greater than 10m.
â— Ventilation during long tunnels, patios, and shafts
During the development period of the mine, it is necessary to dig into the long-distance roadway. When tunneling such roadway, the fan ventilation is often used. In order to obtain good ventilation, it is necessary to pay attention to the following aspects: 1 ventilation should be properly selected, generally using mixed ventilation; 2 when conditions permit, try to use large diameter air duct to reduce wind tunnel wind resistance and increase effective air volume 3 to ensure the quality of the air duct joint; according to the actual situation, try to increase the length of each section of the air duct, reduce the air leakage at the joint of the air duct; 4 wind cylinder suspension force to seek "flat, straight, tight" to eliminate local resistance; There is a person responsible for it, often checking and repairing.
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