The results of an experimental study of the effect of calciumEcontaining reagents on the process of highEtemperature autoclave extraction of alumina from red muds obtained from Timan deposit bauxites by the parallel Bayer-sintering method are presented. The phase composition of products is determined by XRD and EDXR methods. Increased extraction of alumina from red mud when used the surface-carbonized lime in the process is shown.