Selectively removing iron ions from salt solns. - by solvent extracting to oxidise iron ions

Selectively removing iron ions from Zn- and Fe-contg. salt and/or sulphuric solns. is carried out using solvent extraction. The novelty is that Fe2+ is oxidised to Fe3+ in the soln. Pref. the pH of the soln. can be adjusted to absorb Fe3+. Harmful tensides are removed in used acids for being used in the solvent extraction. The ion exchanger is regenerated with acid so that it can be re-used in the extraction. A process for working up zinc/iron solutions having a high zinc content, as are obtained, for example, in hot galvanizing operations, by means of solvent extraction is proposed with the aim of reducing the iron content as far as possible. This is achieved by oxidizing the Fe2+ present to Fe3+ prior to the extraction and adjusting the pH to a value at which predominantly iron(III) is absorbed by the ion exchanger. Depending on the pH set, it is possible to obtain an iron content of less than 1 g/l in the remaining zinc solution. The process of solvent extraction used for this purpose is carried out in a mixer-settler unit (figure). Before the used acid is subjected to extraction, it is advisable to filter it through a suitable adsorbent to remove interfering surfactants. The extraction stage is followed by reextraction with acid, in which the ion exchanger is regenerated.