Research project on copper slag valorization kicked off

M.Sc. Ludwig Blenau
The new interdisciplinary research project by three Tenure Track professors of TU Freiberg aims to find new ways to recover materials from the by-product of copper processing. In the future, those could be used as secondary raw material for glass fibres or for applications in the steel industry.

To this end, the team at the Institute for Non-Ferrous Metallurgy and Purest Materials has carried out initial tests. "The so-called fayalitic slag can be split into two phases by thermal reduction - an iron-containing phase and a glass phase," says M.Sc. Ludwig Blenau, who is investigating the possibilities for reusing the copper slag as part of his doctoral thesis. "The slag contains iron oxides, which can be reduced to iron if the cooled slag is heated to 1,300 degrees Celsius and carbon is added," he explains. The scientists lead by Prof. Alexandros Charitos have already been able to extract around 50 percent of the iron in this way, and thus verify that the copper slag, in principle, can not only be used in the steel, but also in the glass and mineral fibres industries. At the time, the high iron content in the material mixture prevents glass fibres from being produced from the slag.

Therefore, Assistant Professor Sindy Fuhrmann and her team at the Assistant Professorship for Energy- and Raw Material-Efficient Glass Technology examine the slag in detail and modifie it via chemical modifications so that it can be used for glass fibre production. "We are investigating how the properties of the glass phase of the slag can be adjusted so that fibres obtained from it can be used in the future in the building materials sector, for textile fabrics or in high-temperature applications," says Sindy Fuhrmann.

The separation of a specific copper slags into the iron and glass phases depends largely on its exact chemical composition. In practice, however, this is not always known in detail. This is why Björn Sprungk, Assistant Professor of applied mathematics, is developing a simulation of the process: "We are investigating the effect of varying slag compositions on the duration of phase separation using mathematical-physical models such as the Cahn-Hilliard equation," he explains. "The model-based simulations are experimentally verified and adapted in close cooperation with the two project partners. From the mathematical analysis and with the help of efficient numerical procedures and machine learning methods, a robust process prediction or control is then derived, taking into account the material uncertainties."


The research project "Alternative fibre materials based on copper slags" is a cooperation of Prof. Alexandros Charitos from the Institute of Nonferrous Metallurgy and Purest Materials, Jun. Prof. Sindy Fuhrmann from the Institute of Glass and Glass Technology and the Junior Professorship for Applied Mathematics (Jun. Prof. Björn Sprungk). Over the next two years "Sächsische Aufbaubank" is funding the research project with a total of 800,000 Euros.