Recovery of tungsten and rhenium

Abstract

A process is disclosed for recovering tungsten and rhenium from a relatively impure tungsten and rhenium solution. The process involves adjusting the pH of the solution to from about 9.0 to about 10.0 to precipitate impurities, and removing the impurities. The purified solution is adjusted to a pH of from about 0.5 to about 7.0 with a mineral acid. To the purified solution is added a solution containing sufficient hexamine to subsequently form a first hexamine tungsten solid containing the major portion of the tungsten. The hexamine solution is at essentially at the same pH as that of the pH adjusted purified solution. The resulting hexamine-tungsten-rhenium mixture is agitated at a sufficiently low temperature for a sufficient time to form the first solid and a first mother liquor containing the major portion of the rhenium. The first solid is separated from the first mother liquor. A process is disclosed for accomplishing the above in which a relatively impure tungsten and rhenium solution is purified as above. A hexamine solution which is not pH adjusted is added to the purified solution followed by adjustment of the pH of the resulting hexamine-tungsten-rhenium mixture to about 0.5 to about 7.0 as described above to form a first solid containing the major portion of the tungsten and a first mother liquor containing the major portion of the rhenium, followed by removal of the first solid from the first mother liquor.