Reduction of Ammonium Paratungstate Generated During Hydrometallurgical Processing of Copper-Tungsten(W-Cu) Borings

Abstract

Tungsten-copper (W-Cu) alloy is employed for manufacturing heavy duty contactors, relays, switches etc. During production of such components, W-Cu turnings/borings are generated At CSIR-NML, a process for recovering tungsten and copper from tungsten-copper borings containing 46.01% W, 53.78% Cu, 0.13% Fe and other minor metals as high purity tungsten powder and copper powder has been developed In the present work, the detailed investigation on reduction of ammonium paratungstate (APT) having purity 99.95% by hydrogen gas to produce the high purity tungsten powder was presented. The various process parameters such as temperature, time and flow rate of hydrogen gas were optimized At the temperature of 8000C and 0.1 lpm flow rate a reduction of 77.78% was observed up to 2h time. At 9000 C, with increase in flow rate from 0.1 lpm to 0_3 lpm the increase in reduction was found to be from 63.88% to 99.99% at 1h time. At still high temperature of 1000°C, almost complete reduction was obtained at 0.1 lpm flow rate in 1h time. The effect of beddepth was also carried out. At all temperatures chemical reaction and nucleation control were the rates determining steps.