Abstract: To solve the problems of coal accumulation， coal spattering and insufficient output in ring-type coal feeders， a finite element model for coal unloading process of a ring-type coal feeder was established by discrete element analysis software EDEM. It studied the effects of unloading angle， width of unloading opening and velocity of unloading vehicles on the force of unloading plate， the force of seal cover and the unloading capacity. According to the results， the force of unloading plate was the smallest and the unloading capacity was maximized with an unloading angle of 45°. As for the dual-ring coal feeder with an inner ring of a 900 t/h capacity and an outer ring of a 1 300 t/h capacity， the unloading openness width for the inner and outer rings exert the least influence on the force of the unloading plate and the seal cover ，and the unloading capacity，when it is 1 600 mm .Thus，it is the most ideal width for unloading openness. The variation of unloading vehicle velocity can barely impact the maximum output. The research on unloading parameters of ring-type feeders laid a foundation for the feeders´ stable operation.

Key words: ring-type coal feeder, discrete element method, coal unloading angle, width of unloading openness, unloading vehicle velocity