Fig. 1. Effect of microwave pretreatment on flotation recovery of barite
(a): Recovery rate under different dosages of sodium oleate; (b): Recovery rate under different pH values

Fig. 2. Infrared spectra of barite before and after interaction with sodium oleat

Fig. 3. Infrared spectra of the interactions between barite and sodium oleate under different microwave heating time
a: 0 s; b: 10 s; c: 30 s; d: 60 s

Fig. 4. High resolution spectra of barite flotation before and after microwave pretreatment
(a): 3 000~2 800 cm^-1; (b): 1 200~1 050 cm^-1; (c): 1 000~970 cm^-1; (d): 650~600 cm^-1

Fig. 5. Fitted smoothed and second derivative spectra of barite treated by microwave heating for 0 second
(a): 3 000~2 800 cm^-1; (b): 1 200~1 050 cm^-1; (c): 1 000~970 cm^-1; (d): 650~600 cm^-1

Fig. 6. Fitted smoothed and second derivative spectra of barite treated by microwave heating for 10 seconds
(a): 3 000~2 800 cm^-1; (b): 1 200~1 050 cm^-1; (c): 1 000~970 cm^-1; (d): 650~600 cm^-1

Fig. 7. Fitted smoothed and second derivative spectra of barite treated by microwave heating for 30 seconds
(a): 3 000~2 800 cm^-1; (b): 1 200~1 050 cm^-1; (c): 1 000~970 cm^-1; (d): 650~600 cm^-1

Fig. 8. Fitted smoothed and second derivative spectra of barite treated by microwave heating for 60 seconds
(a): 3 000~2 800 cm^-1; (b): 1 200~1 050 cm^-1; (c): 1 000~970 cm^-1; (d): 650~600 cm^-1