Rhenium recovery from ammonia solutions

[Zn(NH3)4](ReO4)2-tetraamminezinc diperrhenate salt has been synthesized. Salt composition has been confirmed by chemical, X-ray phase and infrared spectroscopic analyses. Salt behavior in water, aqueous solutions of inorganic and organic acids and ammonia has been studied. It has been determined that the salt is decomposed in water and acid solutions with the conversion of zinc and rhenium in different phases (solid or aqueous). At the same time, salt is dissolved in ammonia; salt solubility increases with the increasing ammonia concentration. On the basis of acquired data, a process has been developed to recover rhenium from mother liquor containing rhenium to produce ammonium perrhenate. The process has been tested on pilot scale and put into practice at two manufacturing works in Kazakhstan.