Extraction of rhenium from molybdenite concentrates

By-product molybdenite concentrates from copper mines are the most important source of rhenium. The rhenium content is low, generally in the few hundred ppm range. Almost all of these concentrates are roasted to technical grade molybdic oxide, the most common molybdenum product sold commercially. Rhenium oxide is volatilized at high roasting temperatures and condensed downstream at lower temperatures, eventually reporting to the scrubber liquor as a dilute solution. This paper reviews several hydrometallurgical approaches that have been used commercially and/or researched and recommended to recover the rhenium from such dilute solutions. The methods include cementation, ion exchange, solvent extraction, activated carbon adsorption, selective leaching/precipitation, and crystallization for concentration and purification steps. Ammonium perrhenate is typically the end product.