A new approach for the treatment of copper electrorefining anode slime based on hydrometallurgical route involving sulfuric acid leaching with additives such as manganese dioxide and sodium chloride has been developed at National Metallurgical Laboratory (NML), Jamshedpur, India. Mineralogical characterization of the anode slime and the residues after various leaching treatments, carried out by XRD, SEM, and EDX studies, are reported in this paper. The XRD studies of the untreated anode slime sample revealed the presence of CuSO4.5H(2)O, NiO, CuSe, BaSO4, and (Cu0.2Ni0.8)O phases. NiO crystals and selenide rings were found in the SEM studies. After sulfuric acid leaching, the residues under X-ray diffraction analysis showed the absence of the (Cu0.2Ni0.8)O phase. When MnO2 was added during sulfuric acid leaching, the new phases MnSe and CuSeO3.2H(2)O were found in XRD studies of the residue. The general view of the residue under SEM revealed a number of porous structures favoring the ash-diffusion-controlled reaction in leaching. Leaching with both MnO2 and NaCl in the sulfuric acid medium resulted in precipitated AgCl in the residue, as observed by XRD studies. The porous AgCl mass observed under SEM confirmed the ash-diffusion-controlled nature of the leaching reaction.