Thermodynamic analysis of fuming process for treating goethite residues

To learn about the chemical composition and microstructure of goethite residue and analyze its thermodynamic characteristics, the residue was studied by chemical analysis, phase analysis, morphology observation and thermogravimetric analysis. The results show that: Iron, lead, zinc and other elements mainly exist in the form of sulfate in goethite residue. In the fuming process, the sulfate decompose into oxides and then reduce into metals under the action of reducing agent. PbO and ZnO could be maximally reduced if the reducing atmosphere is reasonably controlled. The metal vapor is oxidized by air again in the upper chamber of the fuming furnace and received from the flue-gas recycling system, slagging. Stable and harmless vitreous slags could be eventually obtained when some appropriate fluxes were added.