SELECTIVE RECOVERY OF RHENIUM FROM GAS-SCRUBBING SOLUTIONS OF MOLYBDENITE ROASTING USING DIRECT PRECIPITATION AND SEPARATION ON RESINS

Rhenium, a by-product of molybdenum's extractive metallurgy, can be re covered from acidic gas-scrubbing solutions by using the techniques of direct precipitation and separation on resin. Direct precipitation is achieved by using tetraphenylphosphonium bromide (phi4P). This techni que yields an organometallic precipitate containing more than 25% Re a nd less than 1% Mo and Se. The reaction is fast and selective, with a stoichiometry phi4P/Re = 1/1. Separation on resins is achieved with a weak base anionic resin of the tertiary amine type. By using the reflu x method, the weakly coadsorbed molybdenum and selenium are removed by a concentrated sulfuric acid solution containing rhenium. Rhenium is then selectively eluted by an ammoniacal solution from which pure ammo nium perrhenate is crystallized.