text: This process was developed by the National Smelting Company  at Avonmouth Docks, England, in order to increase production, increase efficiency, and decrease labour and maintenance costs. L. J. Derham proposed using a spray of molten lead droplets to rapidly cool and absorb the zinc vapour, despite the high concentration of carbon dioxide. The mixture is then cooled, where the zinc separates from the lead. The first plant using this design opened up in 1950. One of the advantages of this process is that it can co-produce lead bullion and copper dross. In 1990, it accounted for 12% of the world's zinc production.
  The process starts by charging solid sinter and heated coke into the top of the blast furnace. Preheated air at  is blown into the bottom of the  furnace. Zinc vapour and sulfides leave through the top and enter the condenser. Slag and lead collect at the bottom of the furnace and are tapped off regularly. The zinc is scrubbed from the vapour in the condenser via liquid lead. The liquid zinc is separated from the lead in the cooling circuit. Approximately  of lead are required each year for this process, however this process recovers 25% more lead from the starting ores than other processes.