## 3 Results and Discussion
### Thermal Behavior
The second sharp decrease in mass occurring from 600 to 800 \({}^{\circ}\)C is likely due to the decomposition of residual calcium carbonate, as the loss of mass corresponds to significant peaks in CO and CO\({}_{2}\). For instance, at 1 atm pressure, CaCO\({}_{3}\) decomposes in the range 900-1200 \({}^{\circ}\)C. However, under argon flow, calcium carbonate decomposes to a lower temperature, typically in the range 550-950 \({}^{\circ}\)C [25] Another source indicates the decomposition peak at 750 \({}^{\circ}\)C [26], whereas [PERSON] et al. [27] indicate that CaCO\({}_{3}\) decomposes in the temperature range between 570 and 830 \({}^{\circ}\)C. Thus, the CO\({}_{2}\) peak is certainly associated to calcite decomposition. The FD13 briquette consists mainly of FMC (69.7 wt.-%). It also has a significant amount of added water (11.7 wt.-%). Figure 9 shows a diagram of the TGA-MS analysis. Water appears to be released from the sample at a temperature of between 100 and 535 \({}^{\circ}\)C. At around 250 \({}^{\circ}\)C, a small amount of mass is lost, probably due to the decomposition of starch and fibers. This is consistent with the small CO and  
Figure 8: BC03 TGA-MS diagram. Figure 7: X-ray diffraction (XRD) pattern of CC02 briquette after TGA-MS test. CO\({}_{2}\) peak. CO\({}_{2}\) also peaks significantly near 533\({}^{\circ}\) C, indicating that reduction takes place. Two more significant CO and CO\({}_{2}\) peaks appear near 680 \({}^{\circ}\)C accompanied by a steep and short decreasing mass curve, likely indicating another reduction. From 1200 to 1600 \({}^{\circ}\)C, the biriquette lost more than 20% of its total original mass accompanied by a release of CO, indicating that high temperature reduction took place during this stage. The analysis of the residue collected from the TGA crucible shows that a small fraction of metallic manganese was obtained by the reduction of manganese oxide (Figure 10). However, the main product after the thermal test was manganese silicide carbide (Mn5 SiC). This is a typical product of carbothermic reduction of manganese ores, as stated by [PERSON] [28]. A residual fraction of hausmannite (Mn3O4) and Mn2O3 bearing compound (potassium birnessite) was observed. Figure 11 shows the TG-MS diagram of MA604B. MA604B mainly comprises grinding sludge and oxy-cutting fines. Grinding sludge and oxy-cutting fines consist for the most part of iron and iron  
Figure 10: XRD pattern of FD13 biriquette after TGA-MS test. Figure 9: FD13 TGA-MS diagram. oxides. In addition to grinding sludge and oxy-cutting fines, the briquette contains injection carbon which is mostly carbon. Water appears to be leaving the sample just under 100 \({}^{\circ}\)C up to 400 \({}^{\circ}\)C. Again, a small mass change near 250 \({}^{\circ}\)C accompanied with CO and CO\({}_{2}\) peaks suggest that fibers and starch are decomposed. Starting from a temperature of around 700 \({}^{\circ}\)C, it can be seen that there is continuous mass loss accompanied by emission of CO and CO\({}_{2}\). This indicates that carbon is utilized to reduce iron oxides in the following order Hematite \(\rightarrow\) Magnetite \(\rightarrow\) Wuestite \(\rightarrow\) Metallic iron. Around 1100 \({}^{\circ}\)C, the mass loss becomes steeper, suggesting that further iron oxide reduction takes place. A summary of TGA-MS results is presented in Table 5.