Process for processing a waste etching solution containing a fluorine component and an ammonia component to recover valuables therefrom

摘要

A process for recovering valuables from a waste etching solution containing a fluorine component and ammonia component is provided comprising recovering respectively a fluorine component and ammonia component in the waste solution and recovering a potassium and/or sodium component used for processing the waste solution, and utilizing respectively the recovered components for preparation of an etching solution or reusing or recycling for processing the waste solution. That is, this process comprises adding at least one of potassium hydroxide and sodium hydroxide to the waste etching solution containing a fluorine component and an ammonia component to form hydroxides of metal ions dissolved in the waste solution, filtering the neutralized solution for separation of the metal hydroxides, heating the filtrate by steam injection to recover the generated ammonia as ammonia gas, aqueous ammonia or liquid ammonia, then subjecting the aqueous solution (KF and/or NaF solution free from ammonia components) after recovering the ammonia component to processing using a monopolar or bipolar membrane to recover the fluorine component as an aqueous hydrofluoric acid solution, further recovering at least one of the potassium component and sodium component as at least one of potassium hydroxide and sodium hydroxide and recycling and reusing the recovered ammonia and recovered aqueous hydrofluoric acid solution for the preparation of a new etching solution and at least one of the recovered potassium hydroxide and sodium hydroxide for processing the waste etching solution as a neutralizing agent.