A study on the mixing of flour in a motionless Sulzer (Koch) mixer using a radioactive tracer

This work was concerned with the evaluation of the motionless Sulzer (Koch) mixer for radial mixing of flour. A radioactive tracer technique was employed. The tracer employed, mainly radiosotope ⁵⁶Mn, was created by neutron activation with a neutron flux of 1.44 × 10¹² n/cm² sec. The method has a high degree of accuracy and the advantage that no physical differences exist between the bulk and tracer materials. The concentration distribution in the radial direction was measured, and the resulting degrees of mixedness of the mixture after passing through the mixer for 1, 2, 3, 5 and 10 passes were determined. The degress of mixedness in the radial direction increased with the number of passes. The experimental results were compared to the same mixture passing through an empty column without mixing elements inserted. The comparison indicated that the mixing elements enhanced the mixing process in a predictable way. Finally, a mechanistic model was developed and verified by the experimental results.