Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

This study was performed to investigate the stability and mineralogical characteristics of sludges produced by chemical precipitation of plating wastewater. Leaching tests were carried out for real sludges from the N plating union and synthetic sludges. Synthetic sludges were prepared from individual Cu, Ni, Cr and Zn synthetic wastewaters and mixed synthetic wastewater of these metals. Removal ratio of Ni was found to be low(94.7%) in the chemical treatment process of N plating union which resulted in high concentration(49.8 mg/l) in effluent water. Leaching test of sludges showed high leaching ratio of Cu(9.1%) and high concentration of leachate(9.79 mg/l) more than three times of leachate standard of Korea (3 mg/l). And Ni, of which the leachate standard does not exist, showed even higher leaching ratio(35.8%) and high concentration of leachate(28.27 mg/l). X-ray diffraction analysis revealed no metal hydroxide in both sludges from the N plating union and mixed synthetic sludge. However, except Cr sludge, other individual metal sludges contain compounds which might be metal hydroxides and/or metal oxides.