The Outokumpu Lead Process

The Outokumpu flash smelting process for lead is an extension of the successful flash smelting technology developed by Outokumpn for copper and nickel and applied to lead concentrates. It was developed and piloted at a 5 t/h treatment rate in the late 1980s bnt has not been commercially applied. 

Lead concentrates are dried and fed to a flash burner with 95 per cent oxygen gas, located at the top of a smelting shaft. A high lead slag and some bullion are produced and collect in the base of the furnace. Gases rich in SO2 pass up through a separate off-take shaft to cool and allow volatile lead compounds to sulfate and be separated as a fume for subsequent collection in the waste heat boiler and 

Off-gas from the electric furnace can contain significant amounts of lead and zinc, which are oxidised to a fume by the addition of air in an after burner chamber. If high zinc recovery is required from the slag the electric furnace temperature must be raised, but this will cause a substantial increase in the amount of lead to fume. Bullion and slag are separately and continuously tapped from the electric furnace. 

The efficiency of the electric furnace for reduction and the degree of fuming of lead are the key areas of concern with this process, but no commercial scale data is available to demonstrate performance. Indicative consumption figures for a high-grade lead concentrate of 76 per cent Pb have been given as  

Ashman, D W, Goosen, D W, Reynolds, D G and Webb, D J, 2000. Cominco s new lead smelter at Trail operations, in Proceedings Lead-Zinc 2000, TMS Symposium, pp 171-185. 

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