Flotation of synthetic metal phases through the example of fine fractions of waste incineration bottom ashes

• Applicant: Professor Dr.-Ing. Daniel Goldmann, since 1/2019
• Subject Area: Mechanical Process Engineering
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 403179546

Against the background of declining resources and the ecological and social impacts of raw materials extraction, alternative ways to secure the raw material supply raise in importance. Especially wastes containing fine-grained and finely disseminated metals possess a large potential, which is currently unexploited. Whereas the processing of coarse secondary raw materials is state-of-the-art, metal recovery from fine-grained wastes and waste fractions often does not take place due to the increasing process requirements and a lack of knowledge about the contained synthetic metal phases. Examples are slags, bottom ashes and flue dusts from metallurgical and incineration plants as well as dusts from the mechanical processing of electronic scrap.Within the scope of this project, the characterization and processing of fine fractions from waste incineration bottom ashes will be investigated as an example. They were selected because, on the one hand, they possess a significant recovery potential, especially for copper, and, on the other hand, own investigations regarding the flotation of synthetic copper phases from these fractions showed promising results. However, for a further development of this approach fundamental knowledge regarding the physico-chemical properties of the metal phases and interactions between these phases and floatation reagents is missing. In order to close this gap, first, a representative selection of waste incineration and refuse derived fuel bottom ashes will be characterized chemically and mineralogically within the project. Afterwards, the most relevant identified metal and matrix phases will be synthesized and important flotation properties determined (inter alia zeta potential, contact angle) followed by studies on interactions between the phases and potentially suitable flotation reagents (collectors, depressors, activators and frothers). These studies will be carried out with individual components as well as mixtures. In the last third of the project, the transferability of the obtained results to real bottom ashes will be investigated.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr.-Ing. Tobias Elwert, until 12/2018