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INTERNATIONAL TUNGSTEN INDUSTRY ASSOCIATION

Information on tungsten: sources, properties and uses

Ferro-Tungsten & Melting Base

Ferro-Tungsten

Ferro-tungsten is a master alloy for the production of tungsten-containing steels.  The raw materials for ferro-tungsten production are rich ore or ore concentrates of wolframite or scheelite.  Also artificial scheelite or soft scrap can be used.  The tungsten trioxide in these compounds can be reduced either carbothermically in electric arc furnaces or metallothermically by silicon and/or aluminum.  Also a mixed carbothermic-silicothermic production is in use.

Commercial ferro-tungsten contains between 75 and 85% W.  It has a steel grey appearance and a fine-grained structure consisting of FeW and Fe2W.  It is supplied in 80–100 mm lumps.

Melting Base

Melting Base is another master alloy in tungsten steel production. It can have various compositions according to the tungsten scrap material in use. The tungsten content varies depending on type between 10 and 38% besides iron and sometimes 5.5% Mo and also 5 to 10% Co.

Different types of scrap materials are mixed to meet the required composition. Reductive melting is done in electric arc furnaces and the melt is finally granulated by casting on a rotating disc and quenching in water (size <10 mm).

 

© 2011 International Tungsten Industry Association
Copyright images courtesy of: H Schulze