Abstract:
Mining efficiency is effectively improved through the adoption of super-long fully mechanized longwall faces. However, when the face length is increased and single-shearer operation is retained, equipment idle time is increased and face-advance efficiency is reduced. To improve the mining efficiency of fully mechanized longwall faces, two-shearer mining processes are designed for 600 m super-long faces. Coal-flow intensity on the armoured face conveyor (AFC) and the associated process parameters are evaluated under various mining processes. Leveraging the cooperative mining of two shearers, mining processes of two shearers traveling in the same direction and opposite direction are proposed. A previously developed spatio-temporal distribution model of coal flow is used to simulate the spatio-temporal distributions of coal flow of the AFC under mining processes of single shearer, two-shearer in the same-direction and opposite-direction. Three mining processes are compared using process cycle time, no-load rate, peak cross-sectional area and volume of coal flow, average transport volume, volumetric fluctuation coefficient, and rated power required for the AFC. Under mining processes of two shearers, the AFC no-loading rate is reduced and resource utilization is improved. Coal-flow intensity is also decreased, and the risk of scraper chain fatigue fracture is reduced. Compared with the same-direction two-shearer mining process, a smaller conveyed coal volume is obtained under the opposite-direction two-shearer mining process. Lower coal flow intensity, a smaller volumetric fluctuation coefficient, and a more stable AFC load are also achieved. Effects of traction speed under two-shearer mining process in the opposite-direction and the coal-flow intensity on the AFC are investigated through seven sets of comparative simulation tests. When the traction-speed ratio is increased, the AFC no-load rate is reduced and operational efficiency is improved. When the ratio is decreased, the AFC no-load rate is increased and operational efficiency is reduced. When the traction-speed ratio is either increased or decreased, the maximum cross-sectional area of the conveyed coal flow is increased. Maximum conveyed coal volume and the average conveyed coal volume are also increased. Meanwhile, the volumetric fluctuation of coal flow is intensified, the AFC rated power is increased, and the mining cycle is shortened. However, the minimum center distance between two shearers remains unaffected.