Size-Enlargement Processes

Numerous benefits result from size-enlargement processes, as will be appreciated from Table 20-35. A wide variety of size-enlargement methods are available a classification of these is given in Table 20-36. 

FIG. 20-62 Comparisons of levels of analysis of chemical reaction and size-enlargement processes. Reprinted from Granulation and Coating Technologies for High-Value-Added Industries, Ennis and Litster (1996) with permission of E G Associates. All rights reserved. 

At the other end of the spectrum, many very fine powders are frequently to difficult handle, and may also give rise to hazardous dust clouds when they are transported. It may therefore be necessary to increase the particle size. Examples of size enlargement processes include granulation for the preparation of fertilisers, and compaction using compressive forces to form the tablets required for the administration of pharmaceuticals. 

Size enlargement processes are used in many industries today with the desired results depending on the particular application. In each case, however, the substitution of granular material for fine powders yields a number of beneficial effects. The benefits and objectives of size enlargement, together with some examples of their application, may be summarized as follows ... 

Of course, in any classification system areas of overlap are unavoidable. Some size enlargement processes involve more than one agglomeration mechanism. For example, thermal after-treatment is quite common to harden... 

Bonding and agglomeration by temperature elevation or reduction are applied either in conjunction with other size-enlargement processes or as a separate process. Agglomeration occurs through one or more of the following mechanisms ... 

By the size enlargement processes, melt agglomeration may be employed to produce multiple-unit solid dosage form. The melt agglomerates are called... 

TABLE 21-20 Considerations for Choice of Size-Enlargement Process... 

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