New Challenge on Determination of the Reasonable Rotation to Revolution Speed Ratio for the Mechanical Activation of Boron Concentrate in Planetary Ball Mill

The planetary ball mill is extensively used for grinding, mechanical activation, mechanical alloying, and mechanochemical synthesis of different substances including nanomaterials. It is very important to determine the optimal operating parameters for high efficiency of the planetary ball mill. However, it is difficult to determine the optimal operating conditions for the planetary ball mill because the motion mechanism within the vial is too complex and many factors affect the motion and they are closely related to each other. In particular, the type and property of powder materials have a great influence on the ball motion and energy, and the optimum operating parameter values, even the ball motion state or mechanism, are different from each other in many studies. In this paper, the effect of the rotation to revolution speed ratio on the several interaction forces, such as the normal, tangential, compressive, and total forces, in the planetary ball mill using discrete element method is investigated for determination of the reasonable rotation to revolution speed ratio for the mechanical activation of boron concentrate. The normal and total forces have maximal values at RRSR = 4-4.5, however, the tangential and compressive forces have no maximal value and continue to increase. The action of the normal force might be greater than both of the tangential and compressive forces, moreover, there might be the action of the total force. It is difficult to determine the optimal rotation-to-revolution speed ratio by consideration with only a few factors such as normal, tangential, compressive and total forces in planetary ball mill, therefore, further research is needed.