A. Fundamentals

It is sometimes desirable to physically separate potential biomass feedstocks into two or more components for different applications. The subject is quite broad in scope because of the wide range of biomass types processed and the variety of separation methods that are used. Even the harvesting of virgin biomass involves physical separation technologies. Examples are the separation of agricultural biomass into foodstuffs and residues that may serve as fuel or as a raw material for synfuel manufacture, the separation of forest biomass into the darker bark-containing fraction and the pulpable components, the separation of marine biomass to isolate various chemicals, the separation of urban refuse into RDF and metals, glass, and plastics for recycling, and the separation of oils from oilseeds. Common operations such as screening, air classification, magnetic separation, extraction, mechanical expression under pressure, distillation, filtration, and crystallization are often used as well as industry-specific methods characteristic of farming, forest products, and spe­cialized industries. Since the biomass types are so numerous and the physical separation methods are usually customized, some details of a few specific examples are described here to illustrate the scope of the subject, and how separation is performed. A few potential applications of physical separation methods are also described.