Dietmar Schulze 
Powders and Bulk Solids 
Behavior, Characterization, Storage and Flow

In the engineering community the handling of powders and bulk solids is called bulk solids technology being, at least in Germany, part of mecha- cal process engineering. Process engineering involves study of the change and transformation of material properties. If mechanical processes are used for this transformation, the engineering discipline is called mechanical process engineering. The best known unit operations of mechanical pr- ess engineering are grinding, agglomeration, mixing, and separation. Due to the mechanical treatment, the particles – either single particles or a c- lection of particles – increase in value. To profit from this value increase industry and academia perform research and development. When handling bulk solids, e. g. storing, dosing and conveying, no value increase can be achieved, because the material properties are not changed. What can be achieved is “at most” the elimination of problems which is less interesting research and development compared to the development of new products or processes with the chance to obtain a patent. A silo for the intermediate storage of bulk solids often seems to be only a single, unimportant element for the realization of a larger process. Bulk solid is filled into the silo continuously or discontinuously and discharged later at predetermined points of time in desired quantities. That is not – ways unproblematic. The known problems of arching and ratholing can lead to irregular discharge or complete blockage.

Table of Content

Fundamentals.- Flow properties of bulk solids.- Practical determination of flow properties.- A more detailed look at properties of bulk solids.- Discussion of testers and test procedures.- Properties exhibited by some bulk solids.- Examples of measured flow properties.- Stresses.- Silo design for flow.- Silo configurations.- Discharge of bulk solids.- Segregation.- Silo quaking and silo honking.- Sample problems and solutions.