Method and device for removing impurities in granules

An impurity removal device for removing impurities in granules, comprising a shell with a separation cavity,

• wherein the impurity removal device further comprises A) a first acoustic wave generating device and a second acoustic wave generating device, or B) the first acoustic wave generating device, the second acoustic wave generating device and an acoustic wave solid guide assembly;
• wherein the impurity removal device is configured such that the first acoustic wave generating device automatically emits first acoustic waves having frequencies in the range of 1 Hz-350 Hz and the second acoustic wave generating device automatically emits second acoustic waves having frequencies in the range of 6 kHz-40 kHz simultaneously with the first acoustic wave generating device emitting the first acoustic waves having the frequencies in the range of 1 Hz-350 Hz,
• wherein the first acoustic waves emitted by the first acoustic wave generating device and the second acoustic waves emitted by the second acoustic wave generating device are configured to be transmitted to the granules to be removed in the separation cavity by using a gas as a wave guide medium,
• wherein the acoustic wave solid guide assembly comprises a connected third acoustic wave generating device and a solid wave guide medium, third acoustic waves emitted by the third acoustic wave generating device are configured to be transmitted by the solid wave guide medium to the granules to be removed in the separation cavity,
• wherein the third acoustic waves have frequencies in the range of 6 kHz-40 KHz.