Other Size Enlargement Processes

Spray drying is, in the true sense of the word, an agglomeration technology during which hollow spheres form in the drying tower from dissolved or suspended material. However, since most of the parameters of this process are controlled by unit operations other than those of mechanical process engineering this technique will not be covered in much detail. 

Other microcapsules are produced by surface and in situ polymerization methods or, generally, interfacial reactionsThe capsule walls may be soluble or insoluble and impermeable or permeable, whereby the rate of release of the encapsulated material or the exchange of material through the membrane walls can be adjusted and controlled. Originally, drugs, chemicals, toner materials, pigments, and the like were encapsulated to improve handling and 

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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 ... 

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. 

Tumble agglomeration is the most natural of all size enlargement processes. As solid particles move in relation to each other in the relatively dense bed of a rotating or otherwise actuated containment of some kind or in a suspension... 

In the following, after a short introduction into the sintering mechanisms, sintering as a size enlargement process by agglomeration will be covered. Different parts of the book should be consulted for information on the other meanings of the word. 

Sometimes, simple tumbling motions, for example on the slope of stock piles or on other inclined surfaces, are sufficient for the formation of crude agglomerates [B.48, B.97]. These low-cost particle size enlargement processes are primarily used in a spe-... 

The drying of solutions and the solidification of melts form an integral part of many of the size enlargement methods discussed in other chapters of this book. These are common mechanisms to harden agglomerates and prepare them for further processing and use. A number of the machines men-... 

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