The mixing of free-flowing sand particles of larger size (-0.422+0.595 mm) with non-free-flowing salt particles of smaller size (-0.252+0.353 mm) has been studied in an experimental double-cone blender with no deflectors and with deflectors. In these studies the progress of mixing in the axial and radial directions has been followed separately. Four compositions with mixtures proportions of 20, 40, 60 and 80% sand by weight have been studied. It is observed that for the case with no deflectors complete mixing is rarely attained for compositions containing a greater proportion of free flowing sand particles. In such cases complete mixing can be attained having deflectors at suitable positions in the blender. © 1972.