(205e) Mixing of Spherical and Non Spherical Particles in a Nauta Mixer

Experiments were conducted to determine the effect of fill level and size of particles on the mixing of sand (spherical) and tea (non spherical) in a Nauta mixer. The finer particles of size less than 75 µm were mixed with the coarser fractions of particles namely with size larger than 75 µm ( i.e. with mean sizes of 112.5 µm and 181 µm, respectively) in vessels of approximately 10 liter volume. The mixer was filled with 30 vol %, 40 vol %, and 50 vol % of base materials and was rotated at 4 RPM. Coarser particles was loaded first followed by finer particles in the mixer and was mixed from 30 seconds to 40 minutes. Homogeneity of the mixtures was determined by using Lacey Mixing Index. It has been found that spherical particles such as sand provide good mixing for all filling levels,30%vol,40%vol and 50%vol regardless of differences in sizes of particles. In mixing of non spherical particles, large differences in sizes of particles (M2) produced more homogeneous mixture as compared to small differences in sizes of particles (M1). All filling levels provide good mixing at a longer mixing time, i.e after 3 minutes of operation.

Keywords: Nauta mixer; Lacey Mixing Index; spherical and non spherical.