In the scope of a study commissioned by RWE Power AG, studies were conducted at the FGK research institute on the ceramic suitability of clay raw materials from open lignite mines. In ongoing surface mining, clays are recovered from several-metres-thick and homogeneous mining horizons. The individual horizons differ in their chemical composition and mineralogy, as a result of which a wide and varied spectrum of potentially usable raw materials is obtained. The clays were first analysed in chemical-physical processes. Then their ceramic processing properties were tested and fired samples assessed. The results showed that the properties of the clays meet quality requirements in different ceramic segments. With regard to sustainable supply of raw materials, it would therefore be expedient to utilize these clays in higher-value applications.

Stefan Ginzel (M. Sc.), Forschungsinstitut für Anorganische Werkstoffe - Glas/Keramik-GmbH, Höhr-Grenzhausen