Abstract：Aimed to complete the theoretical system of ballistic separation for coal and gangue underground, this paper has discussed the elastic-plastic behaviors of coal and gangue during the impact process. The of relative position for the initial yield point was firstly determined combining the Hertz contact theory with the Drucker-Prager criterion. There are an approximate linear relationship between the relative position and the Poisson’s ratio. The mathematical models of the relative deformation, the contact force and the relative velocity were then established for the initial yield moment. The function relationship between the contact force and the deformation has been built based on the linear hardening model, and the theoretical model of the rebound distance has been derived by the law of conservation of energy and the relative velocity at the separation moment. The impact and rebound experiment for coal and gangue was carried out on the single particle impact experimental platform. The results show that the rebound distance increases with the initial velocity. The theoretical values of the rebound distance, calculated by the means of the material parameters, are in well agreement with the experimental means when there are few broken coal and gangue at a low initial velocity. The experimental means are less than the theoretical values because of the energy loss when coal and gangue are crushed.
2017, Vol. 38 
