Feasibility Study on the Potential Replacement of Primary Raw Materials in Traditional Ceramics by Clayey Overburden Sterile from the Prosilio Region (Western Macedonia, Greece)

The objective of this study was to investigate the valorization potential of clayey overburden sterile materials from lignite-mining activities in the manufacturing of traditional ceramics. This study aims to contribute toward the sustainable management and use of such waste materials in line with the environmental objectives of the 2030 agenda. To assess this issue, clayey steriles were incorporated in a white clay-body at 20, 50, and 80 wt%, whereas reference samples were also formed from the individual raw materials. Laboratory processing of the ceramics was performed by dry pressing loose powder into rectangular samples and firing at 1000 °C for 4 h. Characterization of the raw materials included chemical, mineralogical, and thermal analysis. The fired bodies were tested for their total linear shrinkage, apparent porosity, water absorption, bulk density, and bending strength according to the relevant standards. The microstructural evolution of the final bodies was analyzed by scanning electron microscopy, which observed differences related to the addition of the steriles. The results showed that the tested clayey steriles can be utilized up to 50 wt% as a secondary raw material in the production of ceramic materials (e.g., bricks) with comparable properties to the reference clay-bodies. Furthermore, the color of the final samples changed from white-creamy to reddish as the content of clayey sterile materials increased in the raw mix.