Radon Monitoring For Small Coal Mines And Relative Safety Key Technology Research

Most of Chinese coal contains high volume gas, gas outburst and gas explosion are the major risk factors. The survey found that the urgent requirement for medium and small coal mines is targeted, affordable remote monitoring equipment and a new method to index and predict gas outburst. Small coal mines are always driven by interests , they often overcrowdly and excessively mine, that leads to two-thirds of the accidents occurred in the medium and small coal mines in China. A system combination of radon monitoring, infrared thermal imaging, remote video surveillance was developed to extend the existing system function, and enhance safety of medium and small coal mine.Radon concentration monitoring method to forecast gas outburst is proposed. Coal mine gas outburst is a dynamic phenomenon with a sudden outburst, and the outburst often causes suffocation, gas explosions and other accidents. Due to the complex of mechanism and mutual restraint among the prominent elements, thus the location prediction to the outburst is very difficult. Gas outburst prediction is a problem of all coal industry, there is no effective way to accurately predict so far. This paper introduces the common methods of gas outburst prediction, and some laws of gas outburst and relative geological structure. In the process of coal formation, the deoxidization environment, and strong adsorption ability for uranium result in generally higher level of radioactive than around rock. High-pressure radioactive gas exits in a closed geological structure. A model to predict outburst by radon concentration is introduced. Our practice shows the effectiveness of this approach and the model is correct.Using a combination of video monitoring, gas monitoring, ventilation monitoring, radon concentration monitoring, a intellectual monitor system was developed to search coal spontaneous combustion, to predict mine hazard and evaluate alarm level. The alarm correctness of new system is more better than old system. The system is intelligent processing capability, adaptability, low cost, which is useful to improve safety of coal mine. Our system applies information fusion method to manager various detectors and combines characteristic factor of the accident. The system has capability of self-learning and adjusts itself according to human alarm processing results, which improves the system's intelligence and automation, reduces false alarm rate largely.High price of coal mine video server equipment baffled it's widely usage in medium and small coal. So we developed embedded video server, which is explosion-proof, dust proof, waterproof, long-term reliable and low cost. It uses H.264 algorithm to compress video, bit rate is small (minimum 64kbps), its video image is clear. Camera worked in low-light conditions, in order to get clear image and extract image feature, dust brush, gray transform processing, adaptive filter technology was developed. High-speed sampling method and advance digital video signal processing were be used to ensure the system can transmitted 53dB signal without attenuation.Communication facilities in coal mining areas, the reliability is bad, for example the sharp time-varying bandwidth of wireless channel, large differences in bandwidth to access the Internet between miners, which seriously reduce effectiveness of video surveillance. Video network transmission has been studied and reliable video transmission module has been developed which can suit to the network bandwidth changing, adapt to different communication media, and adjust the video frame rate and resolution to achieve less than 1 second video delay. The communication module uses some industry configuration software, conforms to industry standards. The third chapter introduces the video transmission module's design, interface, and error control and rate control method.Based on analyzing the conditions of the explosion, explosive accident tree, feature source triggered explosion, A thermal infrared imaging system was build to monitor electric spark, hot object and coal combustion area which triggered gas explosion. With gray scale transform, the interesting target's feature of infrared image is more evident. The image analysis system's processing can be completed in 0.04 seconds, which can capture short time electric spark, while other ordinary video surveillance system cannot effectively do that. Infrared thermal imaging technology can success to find coal mine fire, coal combustion, and high temperature objects and sparks generated by wrong electrical appliances. The system can reduce gas explosion , major serious accidents of coal mine.