Review: Rhenium and its smelting and recycling technologies

Rhenium is utilized as an additive to improve the high-temperature strength and stability of materials, such as nickel-based superalloys, which are employed in jet engine turbine blades, alloys for ultrahigh-temperature thermocouples, and platinum catalysts, which are used in oil refining. Currently, around 80% of rhenium demand is for superalloy production, and this demand has been increasing with the increase in demand for aircrafts. The abundance of rhenium in the earth's crust is only 1 ppb (10⁻⁹), which is less than those of platinum and gold. Owing to the rare and unevenly distributed nature of rhenium, there is the risk of supply disruption and rapid increases in its price. In this article, the recent situation of rhenium and its compounds are reviewed, especially with respect to their demand, distribution characteristics, smelting, and recycling. Some of the technologies recently developed for smelting and recycling rhenium are also introduced.