To achieve the goal of climate-neutral cement by 2050, Swiss cement plants are increasingly relying on the use of calcined clays as clinker substitutes, which can save up to 40% CO2 in the cement production. Beside the reduction in CO2-emission, a further environmental advantage can result if the clay-containing raw materials are not extracted from quarries (primary raw materials), but recycled from mineral waste (secondary raw materials). In Switzerland, gravel washing sludge, a fine residue from gravel processing with a relatively high clay content, is a secondary raw material with high potential for this purpose. Within this MSc thesis, the recycling potential of gravel washing sludge as a raw material for calcined clays will be investigated with laboratory experiments. The main research questions are 1) mineral reactions as a function of temperature 2) reactivity and potential as a clinker substitute material. Beside initial mineralogical-geochemical characterization, the experimental setup involves heating experiments in non-ambient XRD and lab-scale rotary kilns combined with mineralogical analysis and reactivity tests of the calcined material. The understanding of the mineralogical-geochemical material properties of the gravel washing sludge and its calcination and reactivity behavior is key to enable its use on an industrial scale.
This applied MSc thesis is thematically embedded in a multi-year research project investigating the recycling potential of secondary raw materials in the cement industry. There will be a close collaboration with cement plants as well as other research institutions in Switzerland (e.g. EMPA).
Advisors: Dr. Mirjam Wolffers, PD Dr. Georgia Cametti, Prof. Sergey Churakov
University: BE