## 3 Factsage in the Environmental Sector
### Applications in the Field of Air Pollution  
In the realm of air pollution management, Factsage has been utilized for controlling the generation of gaseous pollutants, absorption and capture of gaseous pollutants, as well as treatment and disposal of such pollutants. Some of the study cases are shown in Table 6. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Module Function** & **Case Descriptions** & **Reference** \\ \hline \multirow{6}{*}{Prediction of eutectic properties} & \multirow{2}{*}{Terary phase diagram of SiO\({}_{2}\)-CaO-Al\({}_{2}\)O\({}_{3}\) to predict the melt flow temperature of coal ash.} & [91] \\ \cline{2-3}  & The effect of CaO content on the melting temperature of coal ash was analyzed by plotting SiO\({}_{2}\)-CaO-Fe\({}_{2}\)O\({}_{3}\)-Al\({}_{2}\)O\({}_{3}\) & [92] \\ \cline{2-3}  & Quaternary phase diagrams with different CaO contents. & [93] \\ \hline \multirow{6}{*}{Analysis of reaction products} & \multirow{2}{*}{Terary phase diagram of RECl\({}_{3}\)-O\({}_{2}\)-H\({}_{2}\)O to calculate the effect of temperature and carrier gas composition on the yield of light rare earth oxides prepared by pyrolysis.} & [94] \\ \cline{2-3}  & MgO-Cr\({}_{2}\)O\({}_{3}\)-CaO ternary phase diagram to analyze the phase changes in the preparation of Magnesium chrome brick refractories and to determine that CaO as a slagging agent has little effect on the refractoriness of the material. & [94] \\ \hline \multirow{6}{*}{Mapping areas of strength} & \multirow{2}{*}{The dominant zone of the Zn-S-O system was mapped at different temperatures to study the variation of the stability zone range of each phase with temperature in the oxidative roasting of Zn sulfide.} & [95] \\ \cline{2-3}  & Mapping the dominant region of the Cr-Fe-C-O system in order to analyze the thermodynamic presence of Cr in stainless steel under different conditions. & [96] \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Application study of the Phase Diagram module of Factsage software. With its gas-phase equilibrium calculations, Factsage is useful in controlling the generation of gaseous pollutants [109]. It can determine the chemical composition and concentration distribution of flue gas, providing essential data for adjusting reaction conditions and reducing gaseous pollutants during chemical reactions of gas pollution generation [101]. For instance, [PERSON] et al. [103] employed the Reaction module to simulate the emission rate of VOCs during the preheating process of an oxygen converter and analyze the effect of different parameters on VOC emission rate, thus achieving maximum pollution emission control by comparing different preheating procedures. [PERSON] et al. [104] studied the secondary pollution problem during the preparation of sintered bricks using yellow phosphorus ore and used Equilib and Reaction modules to calculate the thermal transformation process and gas-phase products in the sintering process, determining the types of gaseous pollutants. Lower calcination temperatures were found to be beneficial in reducing harmful gas emissions during the production process. Factsage has also been employed in the study of NO, CO, CO\({}_{2}\), and other pollutant gas emission control, providing a powerful tool for the source control of air pollution [110; 111; 112]. Moreover, Factsage can be utilized to simulate the adsorption and trapping processes of gaseous pollutants, optimizing the reaction conditions for gas trapping [113]. To illustrate, in the field of carbon dioxide capture, [PERSON] et al. [105] and [PERSON] et al. [106] employed Factsage to investigate the capture of carbon dioxide by steel slag and phosphogypsum, respectively. The former employed the Equilib module to ascertain that the carbonation reaction of calcium and magnesium-containing phases in steel slag can occur spontaneously, whereas the latter utilized the Phase Diagram module to confirm the existence of carbonation reaction products.