Patent ID: 7815708

Claim:
A process for the valorisation of metal values in a Zn-, Fe- and Pb-bearing residue, comprising the steps of: subjecting the residue to a flash or agitated bath fuming step, thereby producing an Fe-bearing slag and Zn- and Pb-bearing fumes; and extracting the Zn- and Pb-bearing fumes and recovering Zn and Pb from the fumes; wherein either one or more of CaCO 3 , SiO 2 and MgCO 3 are added as a flux before or during the fuming step so as to obtain a final slag composition with: [ Fe ] [ SiO 2 ] + [ CaO ] [ SiO 2 ] + [ MgO ] 3 > 3.5 ; 0.1 < [ CaO ] [ SiO 2 ] < 1.3 ; ⁢ and 6 < [ SiO 2 ] < 22 , all concentrations being expressed in wt %.