P resently about 15 - 20% of the world's zinc production comes from pyrometallurgical route. The horizontal and vertical retort processes and electrothermal process were used in the past for zinc production but have become obsolete due to high power consumption and low recovery. The only pyrometallurgical process of importance presently is Imperial Smelting Process (ISP).
Imperial Smelting Process (ISP):
Currently about 8 -10% of the world's primary - zinc production are through the Imperial Smelting Process. The process co-produces lead bullion in addition to zinc metal using a mix of lead and zinc concentrates or complex lead-zinc concentrates as raw material. The Imperial Smelting Process is similar to blast furnace processes except that it is operated with hot top whereby preventing reoxidation of zinc vapours. The process consists of basic two operations namely; sintering and blast furnace smelting of sintered lumps to extract lead and zinc simultaneously. The Imperial Smelting Process has the following demerits:
This page has been last updated on 08-09-2005