Recent trends in extraction of selenium & tellurium from electrolytic copper slimes

Anode mud or slime from copper electrolysis, though a byproduct of copper industry, contains many important metals like nickel, copper, selenium, tellurium and noble metals, the recovery of which not only makes copper production economical but also gives important metals. The importance of selenium and tellurium in the modern technological world has attracted the attention of scientists and industrialists all over the world and work on various lines is in progress to recover these metals from anode mud. Selenium and tellurium are mainly present as selenides and tellurides of copper and silver. Conventional and new methods of extraction of these metals from copper slimes are discussed. Out of the conventional methods of soda smelting, soda roasting and sulphuric acid roasting, the last one is most popular. New methods have been discussed under three headings: Hydrometallurgical (leaching with caustic soda, leaching with ammonium sulphide, pressure leaching with alkali and pressure leaching with acid), Pyrometallurgical (roasting and passing through soda, shaft furnace sintering, calcination, calcination with saw dust and vacuum sublimation method), and miscellaneous methods (chlorination). (Shri Narinder Singh, Scientist, and Shri S.B. Mathur, Junior Scientific Assistant, National Metallurgical Laboratory, Jamshedpur)