Leaching behavior of hard metals used in the drilling industry

Claudia Kerschbaumer, Stefan Luidold, Thomas Wolfe, Anthony Smith

Drill bits made of hard metal pose several challenges regarding their recovery. They contain different tungsten compounds such as WC, W or cast tungsten carbide infiltrated with a complex binder alloy. Due to their large sizes they are naturally difficult to break up. As most literature is focused on common hard metal scrap such as spent cutting inserts, it takes new approaches and detailed examination to find a suitable recycling method for drill bit scrap.

This paper deals with the evaluation of a semi-direct recovery process by which the binder phase is selectively digested while the tungsten compounds remain in the form of a pure solid residue. The screening tests showed that with the most effective solutions the samples can be completely digested in only four hours. The feasibility of the process was proven and the products thereof were characterized.