# Rudomain Iron Ore Treatment by High-Temperature Reduction
## 3 Results and Discussion
Results of the identification of physico-chemical and metallurgical properties of iron ores indicated that the Brazilian iron ore, i.e., Carajas, exhibited the highest quality. A total Fe content was found to be approximately 65 wt%, while the major portion of iron was present in form of easy-to-reduce hematite (Fe\({}_{2}\)O\({}_{3}\)). The total Fe content of the iron ore Carajas was analysed by two methods (with XRF analysis, Fe content = 65.23%, with AAS analysis, Fe content = 65.17%). High agreement in the analysis of total Fe was achieved within the XRF and AAS methodologies also in the case of Rudomain and Kirvbas iron ores. The Carajas ore exhibited a very low content of SiO\({}_{2}\) (in form of silica). The Ukrainian ore, i.e., Rudomain, exhibited a lower total Fe content (58.20 wt%) and, by contrast, the highest SiO\({}_{2}\) content. In the case of the SiO\({}_{2}\) analysis in the iron ore Rudomain, larger deviations were recorded within the XRF (13.40%) and AAS (12.95%) methodologies than in the case of the Fe content. The content of SiO\({}_{2}\) is present in this type of ore not only in form of silica (SiO\({}_{2}\)) but also in form of hydrated iron silicate (Fe\({}_{3}\)Si\({}_{2}\)O\({}_{5}\)(OH)\({}_{4}\)), i.e., the form of iron that is the most difficult to reduce. The Rudomain iron ore contained more mineralogical forms of iron in addition to hydrated iron silicate, constedtite (Fe\({}^{2+}\)\({}^{2}\)Fe\({}^{3+}\)(Si,Fe\({}^{3+}\))\({}_{2}\)O\({}_{5}\))(OH)\({}_{4}\), and magnetite (Fe\({}_{3}\)O\({}_{4}\)). The contents of undesirable phosphorus and sulphur impurities were very low for all iron ores. The sulphur content was analysed not only by XRF analysis but also by IR analysis using the Elemental Vario device. There was a high correlation with both methodologies. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Iron Ore** & & & & \\  & & **Krivbas** & **Rudomain** & **Carajas** \\  & & **(Ukraine)** & **(Ukraine)** & **(Brazil)** \\ \hline  & FeTotal & 62.25 & 58.20 & 65.23 \\  & MnIOTAL & 0.07 & 0.04 & 0.57 \\  & SiO\({}_{2}\) & 7.80 & 13.40 & 2.21 \\  & Al\({}_{2}\)O\({}_{3}\) & 1.33 & 1.08 & 1.05 \\
**Chemical** & CaO & 0.28 & 0.13 & 0.10 \\
**composition** & MgO & 0.60 & 0.24 & 0.10 \\
**(wt\%)** & P & 0.03 & 0.06 & 0.05 \\  & S & 0.03 & 0.01 & 0.01 \\  & Na\({}_{2}\)O & 0.180 & 0.150 & 0.005 \\  & K\({}_{2}\)O & 0.040 & 0.028 & 0.006 \\  & Others * & 27.39 & 26.66 & 30.67 \\  & \textless{}0.1 mm & 1.55 & 6.05 & 0.35 \\
**Granulometric** & \textless{}0.5 mm & 23.64 & 41.75 & 12.85 \\
**composition** & \textless{}1 mm & 35.13 & 57.48 & 28.54 \\
**(\%)** & \textless{}5 mm & 62.18 & 86.84 & 55.03 \\  & \textless{}10 mm & 81.36 & 97.04 & 78.35 \\
**Moisture (\%)** & & 2.35 & 1.75 & 1.55 \\
**Bulk specific** & & & & \\ gravity (kg.m\({}^{-3}\)) & \(\rho_{\text{A}}\) & 2820 & 2600 & 2680 \\
**True specific** & & & & \\ gravity (kg.m\({}^{-3}\)) & \(\rho\) & 4460 & 4420 & 4710 \\
**Melting point (\({}^{0}\)C)** & & 1472 & 1453 & 1540 \\  & & & & Hematite, \\  & & & & hydrohematite, \\
**Mineralogical** & & Hematite, & hydrated iron \\
**composition** & XRD & hydrohematite, & silicate, \\  & & silica & magnetite \\  & & & & \\  & & & & \\  & & & & \\ \end{tabular}
\begin{tabular}{c} Others *, primarily an analysis of oxygen and hydrogen in Fe phases. \\ \end{tabular}
\end{table} 
Table 5: Properties of tested iron ores. The results of the identification of the granulometric composition indicated that Rudomain iron ore had the lowest porosity (\(\sim\)97% of grains were sized less than 10 mm). As for Krivbas iron ore, \(\sim\)81% of grains were sized less than 10 mm, while in Carajas iron ore, \(\sim\)78% of grains were sized less than 10 mm. In these iron ores, a proportion of grains sized less than 0.1 mm ranged from 0.35 to 6.05%; as a result, it is assumed that those iron ores must be subjected to grinding in order to achieve more appropriate surface properties and ensure the subsequent production of pellets for the reduction.