The processes of mixing and heat transfer between oil shale ash particles and oil shale particles in a non-reacting rotary retorting were investigated by using discrete element method combined with particle thermal conduction model. The mixing index

the average temperature of particles and the standard deviation of temperature were used as the quantitative indexes to evaluate the effect of mixing and heat transfer. The influences of fill ratio of particles

rotational speed of vessel

diameter of the oil shale particles and flights form on particles mixing and heat transfer characteristics were analyzed. Results indicated that the rotational speed of vessel and the diameter of the oil shale particles are the main factors which influence the mixing and heat transfer effect between particles

but the fill ratio and the flights form are relatively minor. When rotary retorting without flights equipped

with the increasing of the fill ratio or the diameter of oil shale particles

the more serious segregation phenomenon between two kinds of particles occurs

the worse the mixing and heat transfer performance are. But it goes up firstly then down with the increasing of vessel speed. Compared with the rotary retorting without flights

the flights forms have influence of disturbance on particle mixing inordinately

so that the mixing and heat transfer effect between particles can be improved remarkably.