# Rudomain Iron Ore Treatment by High-Temperature Reduction
## 3 Results and Discussion
### Material Research of Metallised DRI pellets
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Reduction**} & \multicolumn{5}{c}{**Chemical Composition (wt\%)**} \\ \cline{2-9}  & \multicolumn{2}{c}{**Degree R\({}_{\text{d}}\) (\%)**} & \multicolumn{5}{c}{**Chemical Composition (wt\%)**} \\ \cline{2-9}  & & **Fe\({}_{\text{TOT}}\)** & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **Na\({}_{2}\)O** & **C** & **S** & **P** & **Others \({}^{*}\)** \\ \hline
**R7** & - & 58.20 & 13.40 & 1.08 & 0.15 & - & 0.01 & 0.06 & 27.1 \\
**DRI 1** & 95.60 & 78.08 & 19.05 & 1.70 & 0.02 & 0.68 & 0.02 & 0.02 & 0.43 \\
**DRI 3** & 79.30 & 72.04 & 17.21 & 2.31 & - & - & 0.05 & 0.03 & 8.36 \\ \hline \hline \end{tabular}  
* Others *, primarily an analysis of oxygen in Fe phases.  
\end{table} 
Table 6: Chemical composition of DRI pellets containing Rudomain 7. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Mineralogical Name** & **Phase Designation** & **Chemical Formula** \\ \hline
**Silicon oxide** & Silica & SiO\({}_{2}\) \\
**Iron hydrogen oxide** & Hydrohematite & Fe\({}_{1.67}\)H\({}_{0.99}\)O\({}_{3}\) \\
**Iron oxide** & Hematite & Fe\({}_{2}\)O\({}_{3}\) \\
**Iron silicate hydroxide** & Hydrated iron silicate & Fe\({}_{3}\)Si\({}_{2}\)O\({}_{5}\)(OH)\({}_{4}\) \\
**Silicon oxide** & Silica & SiO\({}_{2}\) \\
**Iron silicate hydroxide** & Cronstedtite & Fe\({}_{3}\)(Si,Fe)\({}_{2}\)O\({}_{5}\)(OH)\({}_{4}\) \\
**Iron oxide** & Magnetite & Fe\({}_{2.936}\)O\({}_{4}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Mineralogical composition of Rudomain iron ore. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Mineralogical Name** & **Phase Designation** & **Chemical Formula** \\ \hline
**Aluminium iron silicon** & Al-ferrosilicon & Al\({}_{0.7}\)Fe\({}_{3}\)Si\({}_{0.3}\) \\
**Graphite** & Graphite & C \\
**Iron silicon** & Ferrosilicon & Fe\({}_{0.905}\)Si\({}_{0.095}\) \\
**Iron** & Iron & Fe \\
**Carbon iron** & Iron carbide & C\({}_{0.055}\)Fe\({}_{1.945}\) \\
**Silicon oxide** & Silica & SiO\({}_{2}\) \\
**Silicon oxide** & Cristobalite & SiO\({}_{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Mineralogical composition of DRI 1 metallised pellet. as well as the melt with a fayalite-like structure (2 FeO.SiO\({}_{2}\)), and these were reformed in the reduction process into spheres of metallic iron and ferrosilicon with a low content of silica (Fe\({}_{3}\)Si) (Figure 12). The microstructure of Fe and Fe\({}_{3}\)Si produced by the reduction also contained zones with complex oxide compounds based on Fe-Ca-Si, probably formed of hedenbergetic CaFe(SiO\({}_{3}\))\({}_{2}\). Oxides of calcium originated from the ash contained in the charcoal reducing agent, while the major component was CaO-based. A detailed image (Figure 13) facilitates the identification of a regular crystalline structure of iron and ferrosilicon with a low content of silica (Fe\({}_{3}\)Si) produced by the reduction, and on their surface, there are complex oxide compounds based on Fe-Ca-Mg-Si, which were probably formed as a result of reactions between the charcoal ash and the original hematite grains. Similarly, in the study [17], some ferrous oxides contained elements such as Mg and Ca. The study identified higher contents of Ca, Si oxides, and trace amount of Fe and P. After reduction in the samples, porous elements of almost pure Fe and darker segments of Ca and Si oxides were identified [17]. Figure 12: An EDX analysis of the DRI 1 sample (original structure). The microstructure of DRI 3 pellets produced in EIF (Figure 14) clearly shows a smaller amount of grains produced by the reduction that those observed in DRI 1. This finding confirmed the chemical analysis of DRI products, which indicated that the pellets metallised in the EIF retort were insufficiently reduced, and their structure contains rather large zones of FeO and unreacted carbon from the reducing agent.