Treatment method of ferrous waste hydrochloric acid

The invention provides a treatment method of ferrous waste hydrochloric acid. The method comprises the following steps: (1) enabling the ferrous waste hydrochloric acid to react with plenty of scrap iron until complete solute in the solution is ferrite ferrous chloride; (2) concentrating and crystallizing the ferrous chloride solution obtained from the step (1) through a multi-stage vacuum distillation device and a single-stage vacuum distillation device, so as to obtain a ferrous chloride crystal; (3) calcining the ferrous chloride crystal obtained from the step (2) through a rotary kiln, decomposing to obtain hydrogen chloride gas, water vapor and a ferric oxide solid, collecting the ferric oxide solid to obtain a ferric oxide product, and exhausting mixed gas containing the hydrogen chloride gas, the water vapor, a little of ferric oxide dust and combustion tail gas; and (4) cooling the mixed gas obtained from the step (3) through a heat exchanger to form hydrochloric acid droplets.