Characterization of cast iron and slag produced by jarosite sludges reduction via Arc Transferred Plasma (ATP) reactor

Jarosite process is the most widely adopted method for zinc production via a hydro-metallurgical route. Jarosite sludges are classified as hazardous waste by the European Waste Catalogue. Up to now, jarosite sludges were stored in lined pounds within the zinc refinery, representing a pollutant source for subsurface and groundwater. Landfilling is possible only after a stabilization treatment that covers twice the amount of waste to be disposed of. In this paper, a new method to recover the residual iron content within jarosite sludges through an Arc Transferred Plasma (ATP) reactor is presented. Reduction of jarosite sludge leads to the production of cast iron, accompanied by the formation of a glassy inert slag that can be easily disposed of in inert waste landfills, or better, recovered as alternative to stone materials. This process results in the recovery of the whole amount of jarosite sludges, reducing to zero the waste to be disposed of.