(598g) Intensifier Bar Blending Analysis and Scale-Up Using X-Ray Tracer Particles

Of the various unit operations used to manufacture solid oral dosage forms such as tablets, bin blending is a crucial and not well characterized unit operation. Bin blending is frequently employed and multiple blending steps are often required to produce a single batch of tablets. Bin blending is also particularly sensitive to scale-up in comparison with other unit operations (e.g. tablet compression and roller compaction) because it requires a larger bin and cannot just be run for longer periods of time. The effects of gravity and associated shear stresses in larger bins are difficult to model/simulate.

The incorporation of intensifier bars (I-bars) into bin blenders has gained in popularity because I-bars provide aggressive agitation of powders. I-bars typically spin at 2000-3000 RPM, with tip speeds of 15-20 m/s and are effective in forcefully mixing powders and dispersing statically-held agglomerates.

In this work, Fe₂O₃ agglomerates were added to I-bar equipped blenders. The I-bar caused breakage and dispersion of the agglomerates and the dispersion rates were measured using a novel 3D X-ray imaging technique. A mathematical model was derived from first principles and used to predict dispersion rates at different scales and under different blending conditions. In total, 59 experiments were conducted, generating nearly 300 samples. Results were analyzed and are presented in order to assess the validity of the scale-up model.