Recovery of rhenium from tungsten-rhenium wire by alkali fusion in KOH-K2CO3 binary molten salt

Tungsten-rhenium wire is used in thermocouple and lamp filament manufacturing due to its good thermal sensitivity and high temperature plasticity, and many waste wires are generated in processing and after use. This work focuses on the efficient recovery of high value rhenium from tungsten-rhenium wire waste with a mass composition represented by W95Re5. The main steps for recovery include alkali fusion, recrystallization, hydrogen reducing and washing. First, W-Re wire was decomposed by KOH-K2CO3 molten salt to produce potassium perrhenate, where the decomposition ratios of W and Re reached 99.36% and 99.80% using a mass ratio of salt to wire of 3:1, m(KOH) of 80% (m representing the mass fraction of KOH in binary salt), a temperature of 800 degrees C and a reaction time of 60 min. Then, the decomposed product was leached by water, and from the resulting lixivium high purity KReO4 crystals were obtained by segregation, which had a perfect rhombic dipyramid morphology and average size of 73.26 mu m. Last, the material was reduced to Re powder at 350 degrees C with a H-2 flow rate of 10 L/min. Re powder, with a purity of higher than 99.5% and fine grain size of 19.37 mu m, was obtained after washing with acid and water. This method provided a potential economic process for the recovery of waste W-Re wire.