Acid recovery of stainless steel pickling process.
Pickling is a unit operation within stainless steel production, which means treating the steel with hydrofluoric acid (HF), and nitric acid (HNO3), also called mixed acid. The whole process generates waste water streams which have to be treated before release.
Bipolar Electrodialysis is applied for acid recovery (HNO, and HF) from spent pickling acid produced in the steel manufacturing process. Bipolar electrodialysis technology has the ability to recover acid from the spent acid for reuse in process. Almost no effluent is produced because all the streams generated during the BED process can be reused. Nitric acid recovery and Hydrofluoric acid recovery of approximately 80 percent can be obtained.