No-Dump Bath Using Trivalent Chromium for the Passivation Process in the Galvanic Industry. Compendium on Low- and Non-Waste Technology

摘要

The use of trivalent chromium for the Blue Passivation process in the Galvanic Industry instead of hexavalent chromium leads to a no-dump bath. The conventional technology for the chromating of zinc coatings utilizes hexavalent chromium and mineral acid, which reacts with the metal. In addition to the chemicals present in the bath, the wastewater also contains zinc that was dissolved from the metal surface. The low-waste technology utilizes Cr(III) and H2O2 which dissolves little zinc and the bath can be replenished with concentrate and reused.