Tungsten metallurgy and recycling. Processes

Tungsten is a rare metal whose content in the earth's crust is estimated at 1µg/g. However, deposits with tungsten concentrations ranging from 0.1 to 0.2% on average can be found, and their formation is explained by a hydrothermal magmatic model.

The aim of extractive metallurgy is to convert the tungsten value of an ore into a pure intermediate compound (tungstic acid or ammonium paratungstate: APT), which is then reduced to metallic tungsten in high-purity powder form.

The most commonly used method for producing pure tungsten powder involves hydrogen reduction of the tungsten oxides resulting from APT calcination.

The treatment processes used to recycle tungsten differ depending on whether the waste is metallic tungsten, heavy metals [W-Ni-Fe-(Cu) alloy] or cemented carbides [WC-TiC-(Ta, Nb)C-Co].

The complete study of the subject includes the articles :

• M 2 378 Tungsten metallurgy and recycling. Processes (this article) ;

• M 2 379 Tungsten metallurgy and recycling. Products and safety ;

• Doc. M 2 380 Metallurgy and recycling of tungsten.