Size enlargement, methods and application

A simple approach to specifying a suitable size enlargement method for a given application is by analogy to techniques currently used for similar materials. If a similar material can be identified in the applications summary of Table 1.4 (or in the more detailed information given in later chapters), and if process objectives are similar in terms of agglomerate size, strength, etc., then the methods used for the established product may well be applicable to the new material. 

Application of experimental devices allows to perform NDT of products, made out of materials of low density (Al-Mg - alloys, Be, plastics) with high defectoscopic sensitivity up to 0,5 %. Inch-size X-ray vidicons used complete with microfocal X-ray tubes and X-ray image enlargement method allow to obtain resolution up to SO pairs of lines per mm. 

In these methods of size enlargement, powders are densified and compacted by application of external force in a confined space. Forces involved to produce a stable agglomerate include solid bridges, immobile liquid bonds, surface forces and mechanical interlocking. The success of the operation depends in part on the effective utilization and transmission of the applied external force and in part on the physical properties of the particulate material. 

It must be stressed that, in the context of this book, the treatment of methods of particle size analysis, which are of great importance for all unit operations of mechanical process technology, must be simple and can not be complete. The task of these chapters will be to provide an overview, to discuss specific problems and limitations of certain methods, and to point out suitable procedures for application in size enlargement. For more detailed information the extensive literature covering this field should be consulted. 

The application of a classic method of size enlargement for the processing of nanoparticles, that is already in use since a time when nanotechnology was not even defined yet, shall be mentioned as a final example. It has been described above that nanosized solids feature an extremely low bulk density caused by their almost instantaneous adhesion and formation of loose floes. Such materials also tend to dusting and exhibit many other unfavorable characteristics. This is also true for industrial carbon black that has been produced in flame reactors for more than half a century... 

Tab. 12.1 Examples of industrial materials that are produced and/or modified with size enlargement by agglomeration and listing of the methods that are most commonly applied Tab. 12.2 Some of the more common benefits of the larger entities that are produced with size enlargement by agglomeration and typical current industrial applications...

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