Albert Barnes Commentary Jeremiah 6:29

"The bellows blow fiercely; the lead is consumed of the fire: in vain do they go on refining; for the wicked are not plucked away." — Jeremiah 6:29 (ASV)

The bellows are burned - Worn out by continual blowing. The prophet has exhausted all his efforts. His heart, consumed by the heat of divine inspiration, can labor no more. Others translate “The bellows snort,” that is, they blow furiously. More probably, “The bellows glow” with the strong heat of the fire.

Plucked away - Separated. The smelter’s object is to separate the metal from the dross.