Hydrogen plasma reduction of Zn and Pb bearing residues in an inductively coupled plasma process.

The application of plasma fuming technology opens up new horizons for the treatment of zinc-bearing residues. The present work uses a lab-scale Inductively Coupled Plasma (ICP) setup to investigate the hydrogen plasma reduction of ZnO and PbO from the CaO-FeO-SiO based slags. Slag particles were melted when passing through the ICP torch, and the ZnO and PbO were reduced into Zn and Pb metal vapor by H molecules and H radicals in the thermal hydrogen plasma. The metal vapor condensed on the particle surface when the particles passed through the plasma torch tail due to the high cooling rate. The PbO and ZnO content increased toward the particle core, implying the PbO and ZnO reduction from the slag particle surface. The increase in H to Ar ratio or H flow rate, power input and S content of the slags accelerated the process.