Zinc

Line Waelz

Waelz kilns are used to treat EAFDust and other residues from Portovesme plants.

The two Waelz kilns treat EAFDust and residues from Portovesme plants.

The process involves zinc reduction caused by the addition of carbons, creating the Waelz Oxide. 

The Waelz oxide is sent directly to the SX plant, or to the washing section if intended for the zinc electrolytic plant.

The Solvent Extraction plant SX

The Solvent Extraction plant SX was commissioned in 2011 and completed in February 2013.

The process consists of two stages:

• LEACHING: Waelz oxide and KSS oxide are leached to produce a ZnSO4 solution (PLS).

• SOLVENT EXTRACTION: Zinc is extracted from PLS by organic solvent and stripped into the acidic solution undergoing the zinc plant’s electrolytic process.

Electrolytic Plant

Impianto Zinco Elettrolitico (commissionato nel 1982) è costituito da diverse sezioni.

• ROASTING: Zinc concentrates and washed Waelz oxides are roasted in the fluid bed furnace, thus obtaining calcine and sulphur dioxide (SO2). SO2 is treated in a double catalysis plant to produce commercial sulphuric acid;

• LEACHING: Calcine is leached under different process steps;

• CELL ROOM: Zinc solution is purified and sent to the electrolytic cell room, along with the SX flow: here zinc is plated into cathodes;

• MELTING AND CASTING: Cathodes are melted and cast into SHG zinc ingots.