Method for heating, concentrating, crystallizing and cleaning waste sulfuric acid

The invention relates to a method for heating, concentrating, crystallizing and cleaning waste sulfuric acid, which comprises the following steps: S1, collecting a preset amount of copper-containing waste sulfuric acid solution which comprises copper ions, ammonium ions, hydrogen ions and chloride ions; s2, carrying out reduced pressure evaporation and concentration treatment on the copper-containing waste sulfuric acid solution in the step S1, collecting condensate water generated in the treatment process, and meanwhile, carrying out purification treatment on waste gas generated in the treatment process; s3, cooling and crystallizing the waste sulfuric acid solution concentrated in the step S2 to obtain a solid-liquid mixture; s4, enabling the solid-liquid mixture in the step S3 to pass through a solid-liquid separation system to obtain copper sulfate and ammonium sulfate composite crystals, and discharging separated concentrated mother liquor into a blending tank; and S5, adding the condensed water collecte