MECA-CLAY

Together with the plant manufacturer thyssenkrupp Polysius, we presented meca-clay technology—used to produce reactive pozzolanic cement grinding additives through purely mechanical activation of clays—for the first time at the 2024 FutureCEM Conference and Exhibition in Brussels.

The technology is based on the trials conducted at the Celitement pilot plant in Karlsruhe since June 2022. For two years, a so-called high-energy stirred media mill has been in operation there, which, in addition to producing Celitements, also enables the mechanochemical activation of other material groups on a semi-industrial scale. With this technology, known from the production of Celitement, all types of clays can be converted into highly reactive cement additives without the use of fossil fuels—solely through electrical grinding energy and without releasing CO₂ from the raw material. In terms of performance, they can even surpass fly ash and slag, which will no longer be available in the long term.

So far, our firing processes for producing reactive cement components have required very high temperatures to convert raw materials into a reactive state. With meca-clay, it has been possible for the first time to increase, or “charge,” the “internal energy” of clay-containing raw materials—available in sufficient quantities in our quarries—so that they can replace very high proportions of cement clinker. Instead of heating clays to 800–900°C to achieve similar effects, we rely on a very specialized and significantly more environmentally friendly electrified grinding process. Up to 70% of the thermal CO₂ emissions from drying and clay calcination can thus be avoided—a significant step toward climate neutrality in the construction materials industry.