## 2 Experimental  
The EAFD was obtained from an electric arc furnace (Xingtai Iron & Steel Corp. LTD, Xingtai, China). As shown in Table 1, Fe\({}_{2}\)O\({}_{3}\) and ZnO were the main components of the dust, together comprising 67.09 wt% of it. In the dust, there was, simultaneously, CaO, MgO, SiO\({}_{2}\), Cr\({}_{2}\)O\({}_{3}\), MnO, and a small amount of Al\({}_{2}\)O\({}_{3}\). Fe and Zn mainly existed in ZnFe\({}_{2}\)O\({}_{4}\), Fe\({}_{3}\)O\({}_{4}\), and ZnO, which were also the main phases of EAFD (Figure 1). As shown in Figure 2, EAFD mainly consisted of small particles, which were less than 2 \(\upmu\)m. Ferrosilicon and carbon powder were used as reducing agents in the experiments. The ferrosilicon contained 74.64% Si and 24.00% Fe, and the content of C in the carbon powder was \(>\)99%. Both were ground into powder for use. Fe\({}_{2}\)O\({}_{3}\), ZnO, and MnO in the EAFD can be reduced to Fe, Zn, and Mn via the reducing agents. Based on Table 1, it can be calculated that when 100 g EAFD was reduced by silicon or carbon, the required amounts of silicon and carbon were 15.63 g and 14.72 g, respectively. Since the ferrosilicon alloy was the carrier of silicon, its silicon content was 74.64%. Therefore, the actual amount of ferrosilicon alloy for 100 g dust was 20.92 g. In order to completely reduce the sample, the amount of the dispensed reducing agent should be slightly excessive. Therefore, the final amount of the ferrosilicon alloy and carbon powder was set to 22 wt% and 16 wt%, respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Component** & **CaO** & **MgO** & **SiO\({}_{2}\)** & **Al\({}_{2}\)O\({}_{3}\)** & **Cr\({}_{2}\)O\({}_{3}\)** & **Fe\({}_{2}\)O\({}_{3}\)** & **ZnO** & **MnO** & **KCl** & **CaF\({}_{2}\)** \\ \hline Content & 6.80 & 5.83 & 5.67 & 0.35 & 5.02 & 40.30 & 26.79 & 2.27 & 0.88 & 1.6 \\ \hline \end{tabular}
\end{table} 
Table 1: The composition of electric arc furnace dust (EAFD) in wt%. This experiment includes two series, referred to as A and B. A total of 50 g EAFD in series A was mixed with 8 g carbon powder, while 50 g EAFD in series B was mixed with 11 g ferrosilicon alloy powder. The uniform mixing samples were charged into the corundum crucible (inner diameter 32 mm, height 65 mm, and wall thickness 1 mm) with a corundum cover. The crucible used in this experiment was completely dried in a muffle furnace under 200 \({}^{\circ}\)C for 3 h in order to eliminate the influence of water. The crucible containing the materials was loaded into an induction furnace (60 kW, 3 kHz) and kept at different temperatures for 30 min. Six temperatures were selected: 700 \({}^{\circ}\)C, 800 \({}^{\circ}\)C, 900 \({}^{\circ}\)C, 1000 \({}^{\circ}\)C, 1100 \({}^{\circ}\)C, and 1200 \({}^{\circ}\)C. The numbers of the experiments are shown in Table 2. After keeping a constant temperature for the predetermined time, the samples were naturally cooled to room-temperature in the furnace. The characteristics of the samples were analyzed through X-ray fluorescence (XRF-1800, Shimadzu, Kyoto, Japan), X-ray diffraction (XRD, X Pert Pro MPD, PANalytica, Almelo, Netherlands), and a scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS, NanoSEM400, FEI, Hillsboro, OR, USA). The total iron, metallic iron, ferrous iron, and zinc content of \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Category** & **700 \({}^{\circ}\)C** & **800 \({}^{\circ}\)C** & **900 \({}^{\circ}\)C** & **1000 \({}^{\circ}\)C** & **1100 \({}^{\circ}\)C** & **1200 \({}^{\circ}\)C** \\ \hline A & A1 & A2 & A3 & A4 & A5 & A6 \\ B & B1 & B2 & B3 & B4 & B5 & B6 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Numbers of the experiments. Figure 1: XRD diffraction pattern of EAFD. Figure 2: The microstructure of EAFD. the samples were determined by the reduction method of titanium trichloride, the volumetric method of ferric chloride and sodium acetate, the volumetric method of potassium dichromate, and flame atomic absorption spectrometry, respectively.