# Utilisation of Mining Waste for Production of Ceramic Tiles
## 4 Discussion  
Waste from the mining industry related to copper and electroencephale production poses significant environmental threats. Therefore, this study examines the complete compositional spectrum of two geographically proximate mining wastes. This approach represents a more sustainable solution than conventional methodologies, as it enables the utilisation of multiple waste streams simultaneously without relying on virgin materials, which offers a sustainable solution and a decrease in the consumption of natural resources. Multiple works have been conducted in this area in recent decades [44; 45; 46; 47; 48]. The innovation of this work lies in demonstrating that by simply adjusting the relative proportions of TG3 clay from Turoszow mining gangue and post-flotation sludge from KGHM-Gilow, it is possible to produce 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 (19.1-20.3% Al\({}_{2}\)O\({}_{3}\)) and kaolinite (67-69%) contributing essential plasticity and strength, while post-flotation waste supplies calcium and magnesium oxides (14.4-17.2% CaO, 5.1-6.9% MgO) acting as fluxes. The fine particle distribution allows one to achieve proper particle packing and sintering behaviour, creating a composite material with adjustable properties depending on the mixing ratio. The location of the rational compositions of the tested sets in the rational composition triangle (Figure 2) lies on the line defining the content of 15-20% of flux and the significantly changeable content of clay minerals in relation to quartz and carbonates. This gives the possibility to design the composition of the mass for both sintered ceramics and quartz-dolomite faience-type ceramics. Since the applied post-production waste had a comparable average amount of feldspars (sodium-potassium), the possible ceramic production technology can be characterised as highly stable. The analysis of the obtained results indicates that further research should be conducted in two directions: masses containing up to 50 %wt of sludge for the production of sintered (stoneware) cladding  
Figure 8: Mechanical strength of compositions after firing as a function of temperature. tiles and masses containing more than 50 %wt of sludge for the production of porous faience-type tiles. In the first case, special ceramics with a mechanical strength of about 45 MPa (min. 32 MPa or min. 35 MPa--ISO 10545-4) (Figure 9) and water absorption below 0.5 %wt or 3 < E \(\leq\) 6%, fired in the temperature range of 1150-1250 \({}^{\circ}\)C, are obtained. This is comparable to commercial porcelain stoneware (35-50 MPa) [43,49]. However, higher values were reported by [PERSON] et al. [43], who stated 87.6 MPa for anorthite-based ceramics with 40 %wt copper slag, and by [PERSON] et al. [50], who achieved 57 MPa with 40 %wt copper slag tiles, confirming the potential of such materials. Other researchers reported bending strengths of tiles in the range 15-25 MPa [51,52], making our faience-type compositions with higher sludge content suitable replacements for non-load-bearing applications. The shrinkage of these sets strongly depends on the sludge content. This research study shows that the greater the amount of sludge in the ceramic mass, the lower the shrinkage of the material and thus the lower the deformation tendency. The optimal sludge content is around 40 %wt. In other words, the sludge content in the ceramic mass will allow the tiles' dimensions to be regulated after firing. In the second case, higher sludge content in the mass, i.e., 50% and more, disrupts this regularity. The reason for this behaviour is the presence of a large amount of dolomite. Dolomite in ceramic masses is a flux agent in the range of higher temperatures (porcelain masses).