# Utilisation of Mining Waste for Production of Ceramic Tiles
## 2 Materials and Methods
### Compositions of Sets Intended for Testing  
The average chemical compositions of the mentioned waste raw materials, calculated as oxides, are presented in Table 4. The underlined values are used to calculate rational compositions. Rational composition analysis is a way of expressing the mineral composition of ceramic masses reduced to three basic components, that is, clay substance (kaolinite), feldspar (orthoclase and albite) and quartz. The three mentioned components are calculated from the chemical (oxide) analysis of the raw materials in the mass recipe. If the amount of CaO and MgO oxides exceeds 0.5%, they are calculated as the content (calcite and magnesite). The carbonate group forms an independent fourth element of the rational composition of ceramic masses. Rational analysis allows for a comparison of mass compositions, the recalculation of compositions when using different raw materials, etc. Ceramic masses that have a similar rational composition are characterised by similar technological and physicochemical properties after firing. Table 5 presents changes in the rational compositions of the ceramic masses according to the mutual shares of individual raw materials. The replacement of Bechatow clay with post-flotation sludge causes a change in rational compositions towards an increase in the share of quartz and a decrease in clay minerals. The change in the amount of feldspar (fluxes) is relatively small and does not exceed 4%. Since the analysed waste raw materials contain significant amounts of calcium and magnesium oxides (especially sludge), the rational composition must include a fourth mineral group, that is, carbonate. Figure 2 shows this schematically. Depending on the mutual shares of the tested wastes, the share of carbonates successively increases (square markers). \begin{table}
\begin{tabular}{c c c c} \hline
**Physicochemical Features** & **“Clean”** & **“Grey”** & **Test Temperature** \\ \hline MgO [\%] & 0.1–0.5 & 0.1–0.3 & \\ Na\({}_{2}\)O [\%] & 0.1–0.2 & 0.1–0.2 & \\ K\({}_{2}\)O [\%] & 2.3–4.5 & 2.9–3.1 & \\ Mechanical strength in & 6.5–12.0 & 2.5–4.5 & 25 \({}^{\circ}\)C \\ raw condition [MPa] & 10.0–11.0 & 10.0–11.0 & 1120 \({}^{\circ}\)C \\ Water absorption [\%] & 8.3–8.8 & 7.0–8.0 & 1180 \({}^{\circ}\)C \\  & 6.0–6.5 & 2.1–4.0 & 1240 \({}^{\circ}\)C \\ Drying shrinkage [\%] & 3.9–4.1 & 5.5–6.5 & \\  & 9.5–11.0 & 8.2–8.3 & 1120 \({}^{\circ}\)C \\ Contractility [\%] & 11.0–12.0 & 10.0–10.9 & 1180 \({}^{\circ}\)C \\  & 12.2–14.8 & 11.6–11.7 & 1240 \({}^{\circ}\)C \\  & 57–69 & 48–49 & 1120 \({}^{\circ}\)C \\ Whiteness after firing [\%] & 51–62 & 43–46 & 1140 \({}^{\circ}\)C \\  & 45–75 & 39–42 & 1240 \({}^{\circ}\)C \\ Loss of ignition [\%] & 13.1 & 13.8 & \\ Kaolinite [\%] & 22–28 & 67–69 & \\ Illite [\%] & 17–27 & 0.1–0.9 & \\ Quartz & 57–62 & 57.6–63.0 & \\ Residue 0.06 mm [\%] & 40–42 & 4.6–5.0 & \\
0–2 \(\mu\)m [\%] & 80 & 55 & \\
0–5 \(\mu\)m [\%] & 90 & 75 & \\ Mixing water [\%] & 33.1 & 33.9 & \\ \hline \end{tabular}
\end{table} 
Table 3: _Cont._The individual sets are located in three fields of ceramic materials, i.e., porous ceramics, sintered ceramics and sintered ceramics sensitive to deformation. This means that it is \begin{table}
\begin{tabular}{l c c} \hline \hline  & **Oxides** & **TG3 clay [\%]** & **Tailing Sludge [\%]** \\ \hline SiO\({}_{2}\) & 60.3 & 61.0 \\ Al\({}_{2}\)O\({}_{3}\) & 19.7 & 4.4 \\ CaO & 0.9 & 15.9 \\ MgO & 0.2 & 6.0 \\ K\({}_{2}\)O & 3.0 & 1.3 \\ Na\({}_{2}\)O & 0.1 & 0.3 \\ Fe\({}_{2}\)O\({}_{3}\) & 1.2 & 0.6 \\ LOI & 13.8 & 10.5 \\ \(\Sigma\) & 100.0 & 100.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Oxide compositions of raw materials used for research.