## 3 Results and Discussion  
### Thermal Behavior  
Figure 4 shows the diagram of the TGA-MS for the CC02 briquette. Strong ion current signals of H\({}_{2}\)O+ (_m/z_ = 18) evolving starting from a temperature around 100 \({}^{\circ}\)C corresponds to sample moisture evaporation. A strong peak is formed at about 310 \({}^{\circ}\)C, which corresponds to binder decomposition. The strong signal persists up to a temperature of 570 \({}^{\circ}\)C, indicating chemically bound water leaving the sample. The signal then deteriorates up to a temperature of 670 \({}^{\circ}\)C, indicating a small amount of bound water is still leaving the sample. A decrease in mass up to 400 \({}^{\circ}\)C is likely to correspond to water leaving the sample as well as decomposition of fibers and starch. The decomposition fibers and starch is supported by strong peaks corresponding to the release of CO and CO\({}_{2}\) detected at around 288 \({}^{\circ}\)C. A decrease in mass starting around 700 and 950 \({}^{\circ}\)C likely corresponds to the reduction of hematite and magnetite, respectively. CO\({}_{2}\) is also detected at 763 \({}^{\circ}\)C, suggesting that significant reduction by CO is taking place, probably due to the iron oxides present in the briquette sample. A significant CO peak is detected near the end of measurement at around 1575 \({}^{\circ}\)C, suggesting that further reduction of oxides is taking place. The results deduced from the MS analysis are confirmed by optical microscopy and XRD analysis of briquette residues collected from the crucible. Most of the briquette converted into metallic material, the microstructure and chemical composition of which are reported in Figures 5 and 6 and Table 4. The iron has assumed a typical cast-iron microstructure, with a pearlitic matrix surrounded by primary cementite and graphite flakes. The non-metallic residue is mainly formed by unreduced iron oxides (especially wustite). An intense and wide XRD peak associated to unburned carbon is detected (Figure 7). Akermanite is due to the reaction between oxides within the bricks and TGA crucible. The BC03 briquette mainly consists of conveyer belt fines (more than 63 wt.-%). The chemical analysis of conveyer belt fines shows that consists of more than 90 wt.-% CaO, which is very stable at high temperatures and cannot be reduced by carbon at the testing temperature range according to the Ellingham diagram. Moreover, water addition during the making of the briquette was 31.1%. Figure 4: CC02 thermogravimetric analysis combined with mass spectroscopy (TGA-MS) diagram. Figure 8 shows the TGA-MS diagram of BC03. During the initial stage of the heat, water and volatiles appear to be leaving the sample. The first sharp drop in the sample mass starting from \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**wt-\%** & **C** & **F** & **Al** & **Si** & **S** & **P** & **Cr** & **V** & **Mn** & **Fe** \\ \hline General & & & & & & & & & & \\ chemical & 6.2 & - & 0.2 & 0.2 & 0.1 & - & 0.8 & - & 0.6 & 92 \\ composition & & & & & & & & & & \\ Spectrum 2 & 3.0 & - & 0.2 & 0.2 & - & - & 0.5 & - & 0.5 & 95.7 \\ Spectrum 3 & 5.1 & 1.3 & 0.1 & - & 0.2 & - & 2.9 & 0.1 & 0.7 & 89.6 \\ Spectrum 4 & 40.5 & - & 0.1 & 0.1 & - & - & 0.5 & - & - & 58.8 \\ Spectrum 5 & 4.1 & & 0.2 & 0.2 & 0.2 & 0.2 & 0.7 & - & 0.7 & 93.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: SEM-EDS chemical composition of obtained metallic material after CC02 dilatometer test (% by weight). Figure 5: Optical microscope microstructure of metallic material obtained after CC02 dilatometer test (Nital 2%). Figure 6: SEM-energy dispersive spectroscopy (EDS) local chemical composition of metallic material obtained after CC02 dilatometer test. around 400 \({}^{\circ}\)C is probably due to the release of chemically bound water. The CO and CO\({}_{2}\) peaks at around 250 \({}^{\circ}\)C probably correspond to the decomposition of starch and fibers.