The division Powder and Slurry Processes is dealing with unit operations in the field of mechanical process technology concerning special product requirements. This includes traditional institute subjects like grinding processes and bulk solid handling as well as particle mixing and separation techniques. The processes, whether they are considered separately or in combination, are characterized fundamentally and finally modulated. Furthermore single process steps and machines are designed according to product specifications varying in a brought range. The current product portfolio ranges from organic materials like fine chemicals, natural products (cellulose, cereals) or waste materials (compressed wood plates) up to inorganic materials which are used for energy storage applications (silicon, carbons), in the ceramic industry (oxides, carbides, nitrides) or in the compounding or mineral sector (cements, ores, quartzes,…). Concerning all these application examples, issues like the products requirements, production rates or analyses methods are as diverse as these products are.
Therefore the division is commanding several machines and instruments, which can handle only a few milligrams as well as some kilograms per hour. The expertise includes especially the production and formulation of slurries in the micro- and nanometer range, as well as the handling and production of dry powders by mixing-, classification- and grinding processes. In addition the storage and transport behavior of dry powders is in the focus of fundamental research. Depending on the product demands we are also working on innovating developments regarding the machine, equipment or analysis side.
In general there is a wide range of characterization techniques available for the examination and evaluation of process steps and the obtained product qualities. For the suspension sector the particle size analysis (DLS, sedimentation, acoustic, laser diffraction), the rheology (rheometer, ultra-sonic sound), the colloidal stability (zetapotential) and the chemical composition (ICP-OES, AAS) can be mentioned as important characteristics. In the field of dry products the particle size, surface properties (BET, IGC, porosimetry), flow ability (shear cells) and the particle (collective) shape (µCT, shape analysis) playing important roles.
Fig. left: Stirred media mill wet operated (left) and SEM images of grinded pharmaceutical particles (right)
Fig. right: Shear cell from Schulze (left), µCT-image of a powder sample (top right) and principle scheme of a powder 3d printer (downright)
The current research focus is on the following topics: