Coal is one of the most important primary energy. Coal firing is the principal cause of global warming and acid rain. With the worsening environmental pollution, the coal preparation becomes very important. In this study, a novel technology based on active pulsing air dense medium fluidized bed (PFB) for fine coal preparation was investigated. The forces acting on particles under different conditions were analyzed. The results show that bubbles in PFB are smaller than those in traditional air dense medium fluidized bed (ADMFB), and smaller bubbles are better for fine coal separation. When f = 1.92 Hz, clean coal was obtained with the ash content reduced by 23.83% compared with raw coal and the tailings ash content was increased by 25.99%. (C) 2014 Elsevier B.V. All rights reserved.