Recovery of Chromium from Sulphuric Acid Leaching Solutions of Mixed Electroplating Sludge by Selective Precipitation

The recovery of Cr from the sulphuric acid leaching solutions of mixed electroplating sludge (（MES)） is studied. After the removal of Cu by solvent extraction, the selective phosphate precipitation is applied for the separation of Cr from Fe, Ni and Zn in the MES leaching solutions . The experimental results show that the precipitation of Cr can be carri ed out stably and effectively and the concentration of Cr in the solutions can be lowered down to ~0.04 g/L. Cr is efficiently enriched in the precipitates which contain 13% of Cr, 0.4% of Ni, 0.1% of Fe and 0.2% of Zn respectively and could be further recovered as economic products.