Matthew Poole and continuators on Jeremiah 51:2

2 And will send unto Babylon fanners, that shall fan her, and empty her land : for in the day of trouble they shall be against her round about .

Wicked men are compared to chaff, Psal. 2.4. Such as execute judgment on them are called fanners, Ier. 15.7. So Mat. 3.12. because as the fanner keepeth▪ what is in the fan unquiet in a continual motion and agitation, by which (advantaged by the Wind) he emptieth it of the chaff: so the executioners of Gods vengeance, by a succession of judgments keeps a people from quiet, till all their chaff be winnowed out, and the fan be emptied of all but the more solid grain.

For (he saith) as the fanner first ridleth what he hath in his fan one way, then another, first throweth it up, then lets it fall into the fan, so the Enemies should be round about Babylon, and God would be on every side and every way destroying them.

Marginal references: chap. 15.7.