Crystallization of sodium perrhenate from NaReO4–H2O–C2H5OH solutions at 298 K

Crystallization of sodium perrhenate (NaReO4) from aqueous solution was studied by means of laboratory scale experiments at 298 K. NaReO4 has a very high solubility in aqueous solution (> 1130 g/L at 298 K) so crystallization was induced by the addition of ethanol (drowning-out crystallization process). This resulted in well crystalline NaReO4 particles which required less energy and water than the conventional evaporative crystallization industrial process. The crystallization of NaReO4 took 5–10 min and could be achieved in 1 or 2 stages by controlling the solution super-saturation by the addition of ethanol in the 25–75 vol.% range. The ethanol in solution could be recovered by distillation and recycled.