An integrated approach for the HCl and metals recovery from waste pickling solutions: pilot plant and design operations

Continuous regeneration of industrial pickling solutions and recovery valuable materials are implemented in a pilot-scale plant including diffusion dialysis (DD), where HCl is recovered, membrane distillation (MD), concentrated, reactive precipitation (CSTR), metal ions recovered different forms. The integration the three processes allows to minimize waste streams generation accomplish closed-loop process, thus increasing environmental sustainability economic impact galvanizing industry. Process reliability was proved through operation demonstrator real environment Tecnozinco SrL hot-dip (Carini, Italy), assessing actual performance fully reducing spent solution disposal recovering useful compounds. Tests were conducted firstly with synthetic then liquors from plant. A high acid (80%) can be achieved unit quantitative metals separation accomplished, iron hydroxide produced at 99% purity. suffers when salts present large quantities, due “salting out” effect, resulting reduced water vapor pressure, though use available low grade heat energy-sustainable MD.