Processing lead-zinc secondary raw materials at Kabwe

The processing of lead and zinc-bearing secondary raw materials at Kabwe (in Zambia) is described. Waelz kilns are used to fume off lead and zinc present in the material to yield Waelz oxide which is leached with sulphuric acid. Zinc is electrowon from solution while lead is produced from the leach residue by smelting it with coke in the presence of soda ash as a desulphurizing agent, A new process being investigated, based on ammoniacal ammonium-carbonate leaching, is also described and preliminary results are presented, The impetus for the new process is the desire to avoid the use of costly soda ash in the lead production process.