A two-dimensional algebric slip mixture (ASM) CFD model was developed to simulate the flow and mixing of liquid-gas-particle system in a rotary drum. The simulations show that there are several flow regimes in slurry phase, including anti-clockwise circulation flow of liquid, rising stream of bubbles, circumferential flow and eddy. The gas disperses mainly in a limited area in the vertical region of bubble stream. Pyrite particle mixing is mainly arised from the movement of baffles, and the distribution of particles is well. The increase of aeration rates would give rise to an increase of the volumetric averaged gas holdup. The increase of rotation speed has little influence in the averaged gas holdup. When three gas spargers were molded in the drum, there is not obvious improvement of gas holdup and particle mixing. (C) 2007 Elsevier B.V. All rights reserved.