Patent ID: 8628740

Claim:
A method of processing a waste iron chloride solution including ferrous chloride, ferric chloride or possible mixtures thereof and optionally free hydrochloric acid, the method comprising the following steps: in a concentration step, concentrating the waste iron chloride solution into a concentrated liquid having a total iron chloride concentration of at least 30% by weight; in an optional oxidation step, oxidizing ferrous chloride contained in the concentrated liquid obtained from the concentration step into ferric chloride to obtain a liquid containing ferric chloride; in a hydrolysis step, hydrolyzing the liquid containing ferric chloride optionally obtained from the oxidation step or hydrolyzing the concentrated liquid obtained from the concentration step containing ferric chloride at a temperature of 165-175° C. while maintaining the ferric chloride concentration at a level of 70 to 80% by weight, to generate a stream containing hydrogen chloride and liquid containing ferric oxide; in a separation step, separating ferric oxide from the liquid containing ferric oxide obtained in the hydrolysis step; in a recovery step, condensing the stream containing hydrogen chloride obtained in the hydrolysis step to recover hydrochloric acid at a concentration of at least 10% by weight; directly or indirectly using condensation energy of the hydrogen chloride containing stream obtained in the recovery step as a heating source for the concentration step; and performing the concentration step under reduced pressure.