## 3 Results and Discussion
### Temperature and Damage Distribution in SM and RM  
The temperature curve of S\({}_{0}\)M was smooth, but the curve of RM fluctuated significantly (Figure 12). The temperature and heating time had a linear relationship in S\({}_{0}\)M due to the constant electric field distribution. In contrast, the electric field distribution of RM varied significantly with the heating time, which resulted in the temperature being affected by the heating time and the electric field distribution. This led to fluctuation in the temperature increase rate. Briefly, S\({}_{0}\)M presented more stable microwave energy adsorption. At 15 s, the maximum temperature of S\({}_{0}\)M was close to RM, but the minimum temperature of S\({}_{0}\)M was significantly smaller than RM. In other words, the difference between the maximum and minimum temperatures in RM was smaller than in S\({}_{0}\)M. Moreover, the average temperature in RM was larger than that in S\({}_{0}\)M. This indicates that the temperature in RM was more uniform than that in S\({}_{0}\)M. The electric field strength of each pyrite particle in S\({}_{0}\)M was different, but it remained constant. This resulted in a linear relation between the temperature of the pyrite particles and the heating time in S\({}_{0}\)M (solid line in Figure 12). In contrast, the electric field strength of each pyrite particle in RM varied with the heating time. This resulted in the temperature of pyrite particles fluctuating with the heating time (dotted line in Figure 12). Therefore, there was a significant disparity in the heating efficiency of pyrites in different models, which caused the uneven temperature distribution related to the heating models. Furthermore, the maximum-temperature pyrite in S\({}_{0}\)M was always D\({}_{0}\), and the minimum-temperature pyrite was always C\({}_{0}\). Both the maximum- and minimum-temperature pyrites in RM changed over time (Table 6). This was because D\({}_{0}\) in S\({}_{0}\)M was always in the hot spot of the electromagnetic field and C\({}_{0}\) was always in the cold spot of the electromagnetic field. However, the strength of the electromagnetic field of each pyrite particle in RM was constantly changing due to the rotation of the coal. Figure 11: Dielectric loss power density of pyrite. Figure 12: Pyrite temperature in S\({}_{0}\)M and RM. The significant difference in the temperature of pyrite in each static model at 15 s was due to the different electric field strengths of the coal sample at different positions (Figure 13). The average temperature in S180M (93.32 \({}^{\circ}\)C) was 3.16 times higher than in S00M (29.50 \({}^{\circ}\)C). Moreover, the minimum temperatures were all close to the initial temperature (20\({}^{\circ}\)), indicating some pyrite particles receiving very little microwave energy in SM. Among them, the minimum temperature in S180M was higher than in other SMs, which was related to the distribution of the electric field. In S180M, the relatively strong electric field covered all the pyrites, making the minimum electric field strength relatively high. The maximum temperature in RM was smaller than in S0M and S180M. However, the minimum temperature of pyrites in RM was significantly higher than that in SM. Furthermore, the difference between the maximum and minimum temperatures in RM was the smallest out of all the models. So, the temperature distribution in RM was more homogeneous than in other models. This may indicate that rotary heating improves heating uniformity and effectively enhances microwave energy utilization. Coal damage in S0M gradually increased during the heating process (Figure 14). The evolution of damage in the coal matrix was closely correlated with the temperature distribution. At 3 s, a small amount of damage occurred around the three hottest pyrite particles (A0, D0, and E0). The pyrites had higher temperatures and thermal expansion coefficients than the coal matrix.