Reductive stripping in vacuum of Fe(III) from D2EHPA

The iron stripping from di(-2-ethylhexyl)phosphoric acid (D2EHPA) constitutes a problem in hydrometallurgical processes: whereas Fe(III) is easily extracted along with other elements such as zinc or cadmium, it is hard to strip it from the organic phase. It is well known that Fe(II) is readily stripped from D2EHPA, so a reduction of ferric to ferrous iron could be a way to solve this problem. In this work, the reductive stripping in vacuum of Fe(III) from D2EHPA has been studied by using SHG zinc powder as a reducing agent. The optimisation of operating conditions, such as degree of vacuum, acid concentration and quantity of added zinc, has been made. The experiments showed that a stripping yield greater than 89% in only one stage can be achieved, depending on A/O ratio, at 80 kPa of pressure. The iron reduction and stripping have been done simultaneously. (C) 2000 Elsevier Science B.V. Ail rights reserved.