Development of a predictive model for component-specific dusting tendency in binary solid mixtures under mechanical stress, taking into account mutual material interaction

• Applicant: Professor Dr.-Ing. Eberhard Schmidt
• Subject Area: Mechanical Process Engineering
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 575548483

The emission behaviour of bulk solids mixtures is characterised by overlapping or competing mechanisms, which leads to complex and as yet insufficiently understood interactions. Although experimental test methods and increasingly detailed modelling approaches are available, there is a lack of reliable prediction models for mixtures, even if the individual components have already been comprehensively characterised in terms of material and dispersive properties. The aim of the intended project is therefore to develop transferable prediction functions that enable a quantitative estimation of the dusting tendency of binary mixtures on the basis of known individual substance behaviour and taking into account material characteristics and interparticle interactions. The analytical modelling is based on thermodynamic analogies, in which microscopic differences are known to lead to macroscopic non-idealities, and transfers these concepts to particulate systems in order to formally describe interactions in the particle structure and their influence on dust release mathematically. Dust release generally requires both sufficient energy input and the presence of potentially dust-forming particles (SP), which are present either as cohesively bound agglomerates or as deposits adhering to non-dust-forming particles (NSP). The primary release mechanisms differ depending on the type of binding and can be divided into shearing and impact processes. To limit the increase in complexity and to specifically analyse reciprocal effects, two special cases are distinguished, depending on whether pure substances and their mixtures consist primarily of SP or primarily of NSP with a defined fraction of SP. This differentiation is retained in the modelling, as binding structures and release mechanisms differ in a system-typical manner and separate prediction functions enable a consistent evaluation. To validate the models, the dusting tendency of defined binary mixtures is investigated experimentally using a rotation test rig that induces mechanical stresses by periodically lifting and dropping the powder in a rotating drum. Released particles are transported out of the drum by an air stream, fractionally separated and then analysed using SEM-EDX to determine their origin in the mixture components and to record the component-specific dusting tendency as well as deviations from the original mixture. In addition, the interparticle adhesion forces between the components are quantitatively determined using atomic force microscopy. For this purpose, force-distance curves are recorded between prepared particles in order to record the binding ratios as parameters for modeling.

• DFG Programme: Research Grants