There exist a number of ways of processing of elastomers. We concern our attention on the process of mixing in batch mixers because the mixing process in the Benbery-type mixers is of great importance for preliminary manufacturing and at the same time this process is the most complicated from the point of view of its mathematical description and thus mathematical simulation. We review the modern methods of mathematical simulation of processes of heat exchange, disintegration, and complex shear flows in a mixed chamber. It is pointed out that when we simulate processes of rheo-dynamics and heat transfer, we should take into consideration the most important characteristics of mixing that influence the quality of mixtures and machine productivity. We consider some probable mechanisms of fracture of agglomerates of fillers. Based on the review presented, we make a conclusion that the process of preparation of rubber mixtures in closed rotary-type batch mixers is yet a bottleneck from the point of view of development of mathematical models for its simulation and development of corresponding methods of optimization.