Sustainable Production of Mullite Grogs from Industrial By-Products

This study focuses on preparing mullite grogs derived from selected waste materials and kaolin treated with advanced technologies to achieve high thermal resistance and low thermal expansion. The investigated waste materials include dust removal RON, slurry DE, feldspar dust removal from Halamky, and waste generated during the feldspar grinding at the Halamky I deposit. These materials (Red kaolin from Vidnava, Slurry DE, Dust-off RON, Feldspar dust-off Halamky) were processed into grogs and subsequently applied for the production of high-mullite ceramics. The influence of cristobalite admixture was also assessed. The chemical composition was determined by X-ray fluorescence (XRF), while the phase composition was analysed by X-ray diffraction (XRD). Amorphous mullite grogs with mullite contents greater than 40% were successfully prepared. Despite the relatively high iron content, the resulting products exhibited the desired white colour after firing and demonstrated properties that make them promising candidates for advanced refractory applications. The study highlights the potential to valorise industrial waste materials for high-value ceramic applications.