Processing Of Etching Sludge From Acid Polishing Facilities

Acid polishing is a well established process in the crystal glass industry, achieving a brilliant finish on glass articles. The polishing acid smoothes the glass surface because rough areas are predominantly solubilised. In time, constituents of dissolved glass form insoluble salts in the polishing acid and precipitate. They have to be removed periodically to avoid polishing flaws. Etching sludge, a highly corrosive and toxic matter, is obtained which requires special treatment. This paper will recall a recycling process developed by Swarovski that allows treatment of etching sludge yeilding a lead carbonate concentrate for the batch. The basics of this process have been know for around 20 years.