Mixing conditions of high concd. suspensions of glass spheres (2.85-3.3 mm in size) in saline (d. 1.15 kg/L) in a stirred vessel were studied by positron emission particle tracking (PEPT) method. The 3-dimensional velocity components for the continuous and dispersed phases were used to verify results of the numerical calcn. carried out by computational fluid dynamics method. The exptl. results were in good agreement with the literature data.