Acid is regenerated and recovered from the spent acid in steel pickling plants. The spent acid containing chlorides of iron is oxidized in a fluidized bed reactor to produce iron oxide and HCl vapors. Whereas iron oxide is a useful bye-product, the HCl is absorbed in stoichiometric quantities of water to obtain 17 to 20% hydrochloric acid and reused for pickling. The company designs and manufactures special tray-type absorbers for the purpose. Finally the gases are passed through columns to limit emissions within pollution control limits.