# Rudomain Iron Ore Treatment by High-Temperature Reduction
## 3 Results and Discussion
### Thermodynamic Study  
Thermodynamic modelling of conditions for the reduction of iron ore using a solid charcoal-based reducing agent was the subject of the subsequent research. The key objective was to create computer simulations of chemical reactions using the HSC Chemistry thermodynamics software [26]. Thermodynamic data were obtained from the software HSC Chemistry (HSC: H, enthalpy; S, entropy; C, heat capacity). HSC Chemistry offers powerful calculation methods for studying the effects of different variables on the chemical system at equilibrium. The aim is to obtain the simplest approach (using this software to calculate equilibrium) that allows one to predict the output parameters (amounts, chemistry, mineralogical composition, and total heat) based on the initial composition analysis. Thermochemical calculations are based on enthalpy (H), entropy (S), heat capacity (Cp), or Gibbs energy (G) values for chemical species. Thermodynamic simulations facilitated predicting the output parameters of direct reduction iron (DRI) products based on the baseline composition of the materials.  
Reduction of iron oxides is one of the most important processes that takes place in reduction reactors (for example, Blast Furnace, Midrex, Corex, etc.). Reduction by carbon is referred to as direct reduction, while indirect reduction is the reduction by gases, for example, carbon monoxide. The stability of individual iron oxides, i.e., Fe\({}_{2}\)O\({}_{3}\), Fe\({}_{3}\)O\({}_{4}\), and FeO, is not identical. Out of all iron oxides, Fe\({}_{2}\)O\({}_{3}\) exhibits the lowest stability. When heated to 1360-1370 \({}^{\circ}\)C, it undergoes thermal dissociation without the involvement of a reducing agent in the air, while intensive dissociation occurs at a temperature of approximately 1450 \({}^{\circ}\)C. The reduction process requires excessive amounts of reducing agents because the reactions of reduction of ferric oxide (Fe\({}_{2}\)O\({}_{3}\)) to ferrous oxide (FeO) and reduction of ferrous oxide (FeO) to iron (Fe) are reversible in certain conditions; this means that Fe and FeO easily oxidise in the CO\({}_{2}\) environment. The reaction of reduction of Fe\({}_{2}\)O\({}_{3}\) to Fe\({}_{3}\)O\({}_{4}\) is irreversible; this means that excessive amounts of a reducing agent are not required, and ferric oxide does not oxidise in the CO\({}_{2}\) atmosphere. Figure 1 shows the feasibility of individual reduction reactions, indicating that the production of iron by reduction using carbon is thermodynamically feasible at temperatures of \(\sim\)700 \({}^{\circ}\)C. With an increasing temperature, the carbothermic reduction will be more effective with a higher degree of metallisation. In addition to iron produced by the reduction, a sequence of several reduction reactions results in the formation of carbides (e.g., Fe\({}_{3}\)C); at temperatures of \(\sim\)800-1100 \({}^{\circ}\)C and in the presence of silica, hematite may reduce to ferrosilicon.  
A step that was necessary in order to perform high-temperature experiments with the analysed commodity was, in addition to identifying its chemical and mineralogical composition, to perform a thermodynamic analysis and define reduction conditions. Those tasks were based on the results obtained by analyses of ores and on a known reducing agent. In our research, we used high-quality charcoal. The effects of a temperature on the reduction process at two predicted levels of carbon consumption per 1 mole of Fe\({}_{2}\)O\({}_{3}\) indicated that it was necessary to use the highest amount of the reducing agent in order to achieve a high degree of metallisation (Figures 2 and 3). With an insufficient amount of the carbon reducing agent, the system contains a high amount of FeO, whereas with