Oxidising elutriation of contaminated sludge containing iron with separation of zinc and lead

摘要

The invention concerns a method for separating non-ferrous metals such as Zn and Pb from sludge containing iron, characterised in that it consists in the following operational steps: non-selective lixiviation of the iron-containing sludge in an acid oxidising medium with a pH less than 2 in a reactor (10) to obtain a lixiviated suspension; a first separating step wherein the lixiviated suspension is separated on a filter (6) into a solid fraction (16) and a solution (20); an oxidising step (9) wherein the solution is oxidised by an oxidising agent (21), thereby converting Fe++ in the solution into Fe+++; re-using the oxidised solution (4) in the lixiviation reactor (10), thereby precipitating Fe+++ in the reactor and eliminating it from the solution during the first separating step (16) while the acid bound in the form of FeCl3 is recuperated.