Technology principle and field application of automatic coal drawing based on the top coal tracker

In order to solve the problem of automatic control of coal drawing in intelligent fully mechanized top-coal caving mining,on the basis of summarizing the deficiencies of the existing coal-gangue identification technology,an automatic coal drawing technology based on Top Coal Tracker with radio frequency identification (RFID) as the core technology was proposed,and the main technical principles and control process of the technology were elaborated. An automatic coal drawing control system based on the technology was constructed,and the system composition and the installation and layout of each part of the system was introduced. It was suggested that multi-round sequential coal drawing should be optimized under the condition of automatic coal drawing and a method for determining the time of each round was given. Taking the 8105 fully mechanized top-coal caving working face in Zhuxianzhuang mine,China,as a research background,a numerical calculation model along the face's inclined direction was established,and the coal-rock interface morphology and top-coal recovery rate under the single-round sequence,single-round interval and multi-round sequential coal drawing method were compared respectively. The results show that the multi-round sequential coal drawing method can achieve a slow and even decline of coal-rock interface. Regarding the recovery rate,the recovery rate of single-round interval coal discharge method is 3.42% higher than that of single-round sequential coal discharge. When the multi-round sequential coal discharge method is adopted,the recovery rate increases with the increase of the number of drawing rounds,and the top-coal recovery rate is the most when the number of rounds is 5~6,reaching 98.01%. Overall,the recovery rate in multi-round coal drawing can be increased by 0.59%~2.00% compared with single-round. At the application site of Zhuxianzhuang mine,the on-site testing of automatic coal drawing based on the Top Coal Tracker was carried out. A total of 20 Top Coal Trackers were arranged along the working face.After the working face advanced though this area,the recovery rate of the Top Coal Tracker was 88.9%,and the average flow velocity of the top-coal was 0.030 m/s. The top-coal flow velocity and other data collected in the field test provide a basis for the design of the number of rounds when using the multi-round sequential coal drawing method. The field test results show that the automatic coal drawing based on the Top Coal Tracker can realize the automatic control of coal drawing.