'societe De Prayon'

Wilhem E Pavonet

Armand L Davister

Renaud F Quatpers

The present invention relates to a process for treating residues from a primary leaching of ferriferous zinc ores by sulphuric acid, with a view to recover a leadbearing by-product, such process comprising a secondary leaching of said residues, by sulphuric acid, within several countercurrent stages, at a temperature comprised between 85.degree. and 100.degree. C., the solid residues of the successive stages being circulated from the first to the last stage, the residue of this last stage being the said lead bearing by-product, whereas the various solutions separated from the second to the last stage are each recycled within the leaching operation of the respectively foregoing stage, and the dual zinc and iron sulphates solution, as separated from the first stage, being the principal product of the treatment. The primary leaching consists essentially of the chemical attack of the zinc oxide of the ore (naturally oxidized ore or roasted sulphur-based ore) by sulphuric acid and yields, as product, the zinc sulphate solution, which after purification, is used for the electrowinning of the zinc contained, whereas the solid residue from this primary leaching, when ferriferous ores are involved, is subject to the above said secondary leaching, in order to recover separately its zinc as sulphate solution, its iron as a precipitate and its lead as final residue of lead sulphate.

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Flemalle-Haute, Belgium

Wilhem E Pavonet