The purification process of hydrogen chloride-by-product produced in production of potassium sulfate by Mannheim method utilizes the "absorption-resolution" principle and adopts the physical method to resolve the problem of separating hydrogen chloride gas from impurity. Said purification process includes the following steps: using washing liquor to wash the furnace gas discharged out from reaction furnace, using absorption liquor to make multi-stage absorption of the hydrogen chloride being in furnace gas, then utilizing resolving tower to resolve out the hydrogen chloride gas from concentrated hydrochloric acid, finally freeze-drying so as to obtain the hydrogen chloride gas whose purity is above 99%. |