# Utilisation of Mining Waste for Production of Ceramic Tiles
## 1 Introduction
Coal waste shows a presence of potentially toxic elements, including heavy metals such as arsenic, lead and manganese, which can pose environmental and health risks if not properly managed [25; 26]. However, these elements also indicate that through appropriate treatment methods, coal waste can be transformed into valuable raw materials. Techniques such as gravimetric separation, flotation and chemical stabilisation have been investigated to reduce the concentration of hazardous elements and improve the suitability of coal-derived materials; furthermore, the physical properties of the waste, such as particle size and moisture content, can affect the quality of the final ceramic products, requiring additional processing steps to ensure consistency [27; 28; 29]. The distribution of waste dumps across Poland means that transportation costs can be significant, particularly for remote sites like \"Zelazny Most\" [30]. Annual report presented by KGHM declared that \"Zelazny most\", in 2022, received 28.7 million tonnes of waste and deposits over 667.7 mln Mg of waste, occupying over 495 ha of territory on its own [31; 32]. The coal mining waste dumps occupy over 4000 ha in more than 220 dumping sites, where over 760 million Mg of waste from hard coal mining have been disposed [33]. Moreover, the infrastructure for processing and integrating these waste materials into existing ceramic production lines is often lacking. This results in a situation where only a small fraction of the available waste is utilised, despite the potential for larger-scale applications. In the region of Lower Silesia, two significant waste streams are of particular interest for ceramic applications. The first is post-flotation waste from copper processing, produced through the froth flotation of sedimentary copper deposits from Kupferschiefer formations [34]. The second is clay waste (TG3) from the lignite mine complex \"Turow\" [35; 36], especially grey clays above the II lignite seam. The proximity of these materials (within 150 km of each other) and their complementary properties (discussed in Section 2) suggest potential for combined utilisation in ceramic production. The present study investigates the feasibility of producing ceramic tiles by using these two mining waste streams, with the specific objectives being the following:Evaluate the potential for the simultaneous utilisation of post-flotation sludge and mining clay waste in ceramic tile production. Determine the optimal waste ratios and processing conditions to meet the PN-EN 14411:2016 standard [37]. Assess the technical and environmental benefits of this waste utilisation approach. Establish a foundation for sustainable waste management practices that could be applied even if lignite mining decreases due to CO2 emission policies [38]. The innovation of this work lies in demonstrating that by properly adjusting the relative proportions of TG3 clay from Turoszow mining gangue and post-flotation sludge from the KGHM-Gilow facilities, it is possible to obtain both sintered stoneware-type ceramics and porous faience-type ceramics that meet industrial standards. The characteristics of TG3 clay and post-flotation waste complement each other through their contrasting compositions: TG3 clay provides high alumina content and kaolinite (contributing essential plasticity and strength), while post-flotation waste supplies calcium and magnesium oxides acting as fluxes. The fine particle distribution has the potential to result in proper particle packing and sintering behaviour, creating a composite material with adjustable properties depending on the mixing ratio.