Rectangular Woven Screen,Woven Metal Screen,Welded Wire Mesh Screen,Charcoal Net Anping Red Star Wire Mesh MFG Co., Ltd. , https://www.screening-media.net
Top body slate mine caving accident, according to their scope and the number of casualties cave spalling, and can be divided into a large cave, part roof, turquoise caving three. Roof fall usually occurs in the case of heavy rock and mineral types of exploitation of the mine, metallurgical mine less frequent. This paper mainly studies the local roof and the loose rock, and collectively called the roof accident. Such roofing accidents occur in the following situations: the fractured working face in the roof; the working face of the rock layer in the bedding, joints, and faults; and the work in the deep mine, ultra-deep mine, and blasting Improper work surface.
Analysis of the causes of roof accidents
The occurrence of a roof accident is generally related to many factors such as mine geological conditions, production technology and organization management. According to the statistics of accidents, the reasons for the management of production organizations accounted for 45.6%, accounting for 44.2% of the reasons for material technology, and only 10.2% of accidents caused by risky operations.
First, production organization management
(1) Unreasonable selection of mining methods
Unreasonable selection of mining methods is a major cause of roof failures. According to statistics, there have been nine mining accidents in the mines in the past six years. Among them, 55.6% of the accidents caused by the irregular-column empty-field method and the accident of the house-column method were 33.3%; Accidents in the stope accounted for 11.1%.
(2) The roof support method is unreasonable
The mining face or large section excavation, the unreasonable support method or the untimely support is another main cause of the roof accident. When the roof rock near the working face is relatively broken and the structure is relatively developed, the support method is unreasonable or the support is not timely, and it is easy to cause the roof to suddenly fall off or help, causing an accident. In the 9 incidents of accidents involving casualties in our mine, there were 6 times due to unreasonable support methods or untimely support, accounting for 66.7%.
(3) Improper disposal of pumice
Most of the loose rocks in the roadway occur within 10 meters from the working face. Most of the loose rocks in the stope occur when the roof of the stope is not too high.
Poor pumice treatment, unqualified workmanship, poor inspection, negligence and even no inspection are one of the causes of accidents. Most of the casualties caused by improper pumice treatment are caused by the lack of comprehensive and meticulous inspection of the top of the working face before pumice treatment, as well as the improper position of the pumice treatment and the unskilled technical skills of the excavator. In the middle section of the mine 505, the PD2 stope occurred once because of the improper standing position, and the accident that the pumice smashing stick was slipped down after being treated.
(4) Improper use of protective equipment
When working in a mine, it is often the case that the roof accident is not enlarged due to the improper use of protective equipment. In August 1999, when a migrant worker from Shangkeng Gold Mine went out at the Shangshankou, the helmet was not tied, and the helmet fell when he bowed. It was just killed by a pumice stone falling from the top of the mountain top.
(5) Personnel management can't keep up
First, there are many new workers used in the underground. They do not understand the underground working environment and lack the training of safety knowledge and skills. The old and the new can't connect together, and they can't promptly and effectively “knock and ask the top†and cause accidents. The mine roof accident in our mine in April 2002 was caused by the lack of necessary safety knowledge of the new workers and the death of one person due to improper standing position when handling the roof rock.
Second, the underground management personnel did not pay much attention to the roof management. There was no effective roof management method and supervision and restraint mechanism, so that the roof management was lax, and there was no accident of small roof accidents with casualties. The roof accident with casualties was inevitable.
    Second, material technology
(1) Turquoise detection technology is backward
“Knocking the Top†is a flexible and effective method of testing the turquoise, which is still used in various countries. However, when the crowbar checks and handles the turquoise, there are certain limitations. The data show that when the thickness of the turquoise is more than 0.4 meters and the area is more than 1.5 square meters, the "knocking top" has no use. Some foreign mines also use advanced detection methods such as ultrasonic detection and infrared radiation detection when using the “knocking topâ€. China's small and medium-sized metallurgical mines are limited by technical and economic conditions. Most of them use the crowbar to “knock and ask the topâ€. There are obvious shortcomings such as incomplete detection of the rubrite and threats to the personal safety of the inspectors.
(2) The top board processing technology is not perfect
Spray anchor support is an effective measure to prevent roof accidents. Its construction process is also relatively mature, and it should be widely used in mines. However, most of the small and medium-sized metallurgical mines in China have not been able to use this technology for various reasons, and still use ancient supporting techniques such as wood support, or even without support, so that the effectiveness of mine roof maintenance has been greatly enhanced. influences.
(3) The mining process is unreasonable
Some small and medium-sized metallurgical mines in China, especially some private metallurgical mines, have unreasonable mining processes and even serious process defects. Due to the lack of mining technicians in these mines, the mining method is hard-wired from other mines or books. It is impossible to adopt corresponding mining techniques according to the actual geological structure and lithology characteristics of the mine in time, resulting in the exposed area of ​​the stope, the mining process, Unreasonable mining process, etc., can not be improved in time in the mining process, and some small mines do not even have a downhole technician, which seriously affects the effectiveness of roof management.
Third, the risk of homework
Since the reform and opening up, driven by economic interests, the dangers, tiredness and dirty work of underground mines have been done by migrant workers, and many mines have eliminated the full-time excavation of underground mines. The underground rescue operations are usually part-time by migrant workers. These migrant workers often experience risky work and cause some accidents. In June 2000, a mine accident occurred in which the migrant workers ventured downhole, causing two people to suffer minor injuries.
Precautionary measures for roof accidents
(1) Adjust the mining process in time to ensure reasonable exposure space and recovery sequence, and effectively control the ground pressure
It is necessary to strengthen the experimental research of mine geological work and mining methods, and continuously improve the original design of mining methods to find efficient and safe mining methods suitable for different geological conditions of the mine, increase mining intensity, and timely process gobs. In order to control the stability of the roof of the stope, it is necessary to have a reasonable mining sequence. Therefore, it is necessary to reasonably determine the order of mining of adjacent two sets of veins; it is necessary to strictly control the exposed area of ​​the stope and mining according to different geological conditions and mining methods. Technical indicators such as the height of the empty area enable the stope to be harvested during the period of stable ground pressure.
(2) Strengthening the inspection, observation and treatment of the roof to improve the stability of the roof
The collapse of the top plate is often an important cause of injury. The inspection and treatment of the top stone is a regular and very important task. It is necessary to fix the special person to work according to the prescribed system, in order to ensure the safe production of the roof and prevent the accident of the roof falling off the pine. For some dangerous pits, scientific methods should be used to observe the roof as far as technical and economic conditions permit. At present, domestic economical and simple observation methods include optical stress meter, geophone and rock movement observation. It is necessary to observe and explore the laws of different rock movements and scientifically grasp the roof conditions. For the unstable working roof that has been found, it is necessary to deal with it in time, and use scientific and effective measures (such as spray anchor support) to prevent roof accidents.
(3) Scientifically and rationally arranging the location, specifications, shape and structure of the roadway and stope
It is necessary to avoid the arrangement of the roadway engineering near the geological structure line, because the compressive stress perpendicular to the geological structure line is the largest, which is the main factor for the change and rupture of the rock mass.
It is necessary to avoid the arrangement of wells and lanes in the vicinity of faults, joints, fracture zones in the layers, muddy interlayers and other geological structures. Because the projects placed in these places are more prone to roofing. If the roadway engineering must pass through these zones, corresponding support measures or special construction plans should also be adopted.
(4) Strengthening roof management and improving the technical level of roof management
First, strengthen the training of safety education and safety technology knowledge, improve the technical level of safety management personnel at all levels, establish the "safety first" thinking, obey the rules and discipline, and establish a roof management system for group inspection, group defense, and group governance. There are crowbars on each work surface, and special personnel or concurrent management personnel are set up to take charge of the work of various work faces, set up warning signs, and complete the handover system.
Secondly, combined with the actual situation of the mine, summing up the experience and lessons of roof management, from the provision of geological data, well design, well maintenance technology, construction management, develop a complete set of roof construction management standards for scientific and effective management of the roof provide technical support.
The roof accident is extremely harmful to the mine safety production. Therefore, it is of practical significance to strengthen the roof management of the mine and predict the possible hidden dangers of the underground working face.
The shape and structure of the roadway and stope should be as close as possible to the stress distribution requirements of the surrounding rock. Therefore, the roof of the roadway and the stope should be arched as much as possible. Because the secondary stress of surrounding rock is not only related to the original rock stress and lateral pressure coefficient, but also related to the shape of the roadway. When the arch shape is adopted, the construction difficulty is not large and the roof pressure is not too concentrated, and the roof stability is good.
April 26, 2023