Metals Recovery and Inertization of Zinc Residues in a Pilot TSL Furnace – Juiz de Fora, Brazil

Ing. Sérgio de A. Penchel Jr, Ing. Claudio A. de M. Lima, MSc. Pablo Pina, Ing. Julia M. Martins, Ing. Francisco C. Freire, Ing. Luiz Flavio da Silva, Ing. Ebenezer G. C. Neto, MSc. Tone Takayama

RLE (Roasting, Leaching and Electrolysis) zinc production process used by Votorantim Metais Holding Smelter at Juiz de Fora (VMH JF), Brazil, until recently was the most common employed at Zn companies worldwide. However, since 2011 with the incorporation of Waelz process, VMZ JF becomes one of the few zinc facilities in the world operating RLE and Waelz processes in the same plant. The main objective of the Waelz process was to replace conventional zinc sulfide concentrates for secondary materials with high grade of Zn, to become in a near future a recycling unit, which is its core strategy. This important transformation became the unit into a possible, safe and economic attractive solution for the treatment of third-party waste throughout Brazil, but did not solve its problem of internal residue production. Nowadays at VMH JF, there are two waste dams in the unit, the Fish Dam that is already out of operation, and the Stones Dam that is still in operation. The Stones dam constantly receives waste from the Zinc Hydrometallurgy, and the Iron residue (Jarosite) corresponding to almost 85 % of that amount. This material has significant amounts of metals such as Zinc, Lead, Silver and Indium, and their recoveries combined with the possibility of producing an inert waste (slag) and the end of the Zn industry need for dams, could make economically viable to install a plant for this purpose. This study assesses in pilot scale the efficiency of the pyrometallurgical route on a TSL furnace to processing the material contained in the Waste Dams of Juiz de Fora plant, and if this process route could be a technical and economical solution to finish or reduce significantly the waste generation in the Votorantim Zinc Smelters.