FIELD: chemistry.
SUBSTANCE: invention can be used in chemical industry. In order to treat iron chloride solution wastes containing iron (II) chloride, iron (III) chloride or possible mixtures of said substances and optionally free hydrochloric acid, said wastes are concentrated at low pressure to obtain a concentrated liquid with total iron chloride concentration of at least 30 wt %, preferably at least 40 wt %. If necessary, iron (II) chloride contained in the obtained concentrated liquid is oxidised to iron (III) chloride to obtain a liquid containing iron (III) chloride. Further, this liquid is hydrolysed at temperature of 155-350°C, while maintaining concentration of iron (III) chloride of at least 65 wt %, to obtain a stream containing hydrogen chloride and a liquid containing iron (III) oxide. A separation step is then performed, where iron (III) oxide is separated from the liquid containing iron (III) oxide. An extraction step is then performed, where the stream containing hydrogen chloride obtained at said hydrolysis step is condensed to extract hydrochloric acid with concentration of at least 10 wt %, preferably at least 15 wt %. Condensation energy of the stream containing hydrogen chloride obtained at the extraction step is directly or indirectly used as a heat source at the concentration step.
EFFECT: invention enables to obtain highly pure and easy to filter iron (III) oxide, reclaim hydrochloric acid and reduce power consumption by 30-40%.
13 cl, 2 dwg, 3 ex
