spress b820 pregelatinized starch function in tablets

The high speed intensifier bar (I-bar), when used, is generally centered along the rotational axis of the bin, as represented by the dashed-line cylinder in Fig. The conical section of the bin facilitates emptying of the bin after blending into for example the hopper of a tablet press. The angled axis is considered to reduce the probability of ‘dead zones’ where powders do not mix.

The tumble bin is typically rotated between 5 and 20 rpm (RPM) about an axis that is angled to the walls of the bin (e.g.

In the pharmaceutical industry, the bin shape often resembles a pyramidal cone stacked on top of a rectangular prism as shown schematically in Fig. cement) by tumbling materials inside a rotating container or ‘bin’. Tumble bin blending has been used extensively in various industries to mix powders (e.g. The data show that the process can be reasonably approximated by a first order rate equation, with the rate constant being linearly proportional to vLD 2 /V 4/3. Experimental data are provided from 59 blends, covering a range of tumble bin scales from 8 L to 700 L, and producing 296 samples that were analyzed by X-ray imaging. A novel characterization method involving tracer particles and X-ray image analysis was developed and used to quantify the extent of mixing. To keep the extent of blending constant between two scales, we find that the dimensionless number vLD 2 t/V 4/3 should be held constant where t is the blending time.Įxperimental data are summarized and used to assess the validity of the scale-up model. The model indicates that the quantity vLD 2 /V 4/3 largely determines the blending rate during scale-up where v, L, D, and V, denote the I-bar tip speed, I-bar length, I-bar diameter, and tumble bin volume, respectively. A mathematical model is derived to predict how k changes when scaling to a larger tumble bin with a larger I-bar running at a different tip-speed. In this work, the blending process is described using a first order rate constant, k, to describe the fraction of powder that has been processed by the I-bar. I-bars thus impart significant mechanical dispersive energy into the blend, both in terms of shear stress and in terms of shear strain.īecause I-bars impart so much energy into the blend, it is critically important to devise a good scale-up strategy, thus ensuring that blending conditions that have been established at a small scale can be reliably reproduced at a large scale. While the tumble bin rotates with rotational speeds of 5–20 rpm, I-bars rotate at 1000–4000 rpm, with tip speeds of ~ 14–19 m/s. In recent years, more and more powder blending operations have been augmented with the addition of an intensifier bar (I-bar) in a tumble bin.

Spress b820 pregelatinized starch function in tablets