To provide a dust treating device which can recover zinc and lead separately in high yield from the dust stuck to a dust collecting device of an arc furnace for steelmaking.

In this dust treating device, metallic oxides are reduced to vaporize metallic components by heating the dust containing the metallic oxides such as zinc oxide and lead oxide together with reducing material in a closed vessel 1 under vacuum condition. In this case, the metallic components are liquefied by passing gas sucked from the closed vessel 1 through a piping 20 held at 419-550°C, and dripped down into a liquid basin 22 provided at the lower part of the piping. A throat 24 is allowed to droop from the bottom part of the liquid basin into a liquid storing vessel 23 whose liquid surface is reliesed to the atmosphere and the liquefied metal in the liquid basin is allowed to flow into the liquid storing vessel through the throat. Then, the temp. of the liquefied metal is held at 419-450°C and the zinc 51 and the lead 50 are separated into the upper and the lower parts.