The invention provides a method for treating
pickling wastewater and recovering byproducts through reduced pressure and low temperature catalytic
fractionation, belongs to the technical field of
environmental protection, and especially relates to terminal treatment of
wastewater containing
hydrochloric acid and
metal salts and recycling of wastes. The method comprises the following steps: 1, preparing a material: filtering the
pickling wastewater to remove particles with
large particle sizes, and fully mixing the filtered
pickling wastewater with a catalyst in a mixing device until uniformity; 2, fractioning: pumping the obtained
mixed solution to a low pressure fractioning device, and separating an acid solution at a low temperature under a low pressure; 3, separating
metal salts: allowing the obtained residual liquid to enter a
metal salt separation device, adjusting the pH value until the
metal salts precipitate, and carrying out adsorbing separation by using a rotating magnetic disc; 5, carrying out
solid-liquid separation: allowing
slurry to enter a
solid-liquid separation device, and dehydrating; and 5, carrying out catalyst concentration: allowing the obtained metal salt removed residual liquid to enter a concentration device, carrying out low temperature and low pressure concentration, and returning the obtained concentrated catalyst to make the catalyst participate in the reaction. The reduced pressure and low temperature
catalysis method is adopted to treat the pickling wastewater, so the acid solution and metal salt
recovery rate is improved, the treatment cost is reduced, and the present technological gaps in low-cost, high-efficiency and zero-
pollution treatment of the pickling wastewater are filled.