Condenser lead splash

ISP (Imperial Smelting Process)—a combined lead-zinc process in which oxidized concentrates are reduced with coke in a shaft furnace and the zinc vapor collected in a lead splash condenser. 

There is a requirement to produce -1000 tonnes per month of partially refined lead for return to the two smelters as top-up for their lead-splash condenser circuits. In essence, the process route is the same as given above except for the omission of the debismuthising and final refining stages. 

Zinc-laden gas is formed in a reducing CO/CO2 atmosphere (CO/CO2 3-4) ai metallic zinc is absorbed in a lead splash condenser. 

Crude zinc from the lead splash condenser is refined separately to produce SHG zinc. 

In 1960 the first standard commercial scale Imperial Smelting Furnace (ISF) was constructed at Swansea in the UK, as an adaptation of the lead blast furnace, to simultaneously produce zinc and lead. The furnace operated with a hot top to retain zinc in the vapour phase. The top was sealed and gases passed through a lead splash condenser to strip zinc from the gas phase into a lead-zinc bullion which could be cooled for separation of crude zinc and lead metals. The ratio of zinc to lead production from these units is generally more than 2 1, and lead production from the standard unit is close to 40 000 t/a. Thirteen plants were constructed around the world but due to unfavourable economics a number of these have now closed. Details are given in Chapter 6. 

Zinc is produced as a gas in the furnace and is absorbed in molten lead in a splash condenser. Zinc is then recovered by separation fiom the cooled lead in a cooling circuit external to the condenser. 

Improved condenser design and operation. In designing condensers, water tank model work proved to be invaluable and has enabled the design of the lead splash rotor to be optimised. 

Condensation is the main route leading to the formation of finely dispersed aerosols in nature and industry. The formation of cumulus (composed of water droplets) and cirrus (composed of ice crystals) clouds mainly starts with heterogeneous nucleation on fine dusts and microcrystals of salt. These microcrystals form when splashes of sea water are dried and raised to high layers of atmosphere by convection air streams. 

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