We have studied the change of the specific surface area of the ground powder and the dynamics of balls and powders with several milling parameters such as the ball to powder ratio, the size of balls, the filling ratio, and the rotational speed of the vial in the mechanical activation process of boron concentrate by high-energy planetary ball mill. The results have shown that the ball movement regime for good grinding efficiency of the planetary ball mill is "cascading" or light "cataracting", and contact forces have a greater effect on the grinding of powders than collision forces. The grinding efficiency is related to the compressive force, the contact force, the kinetic energy of the balls, and the number of contacts, however, the compressive force and contact force seem to have a significant effect. The greater the compression and contact forces, the greater the grinding efficiency of powders. (C) 2020 Elsevier B.V. All rights reserved.