The aim of this study is to evaluate the efficiency of thermal treatment on residual copper sludge after separation treatment. The toxicity characteristic leaching procedure (TCLP) concentration, pattern distribution and possible Cu species of simulated copper sludge were analyzed. Parameters such as different reaction time and temperature are also discussed in this study. The TCLP leaching results showed that the TCLP concentration of Cu in thermally treated simulated copper sludge decreased (T = 900 degrees C) as the reaction time increased to 4 h. The sequential extraction results showed that the main fraction of raw simulated copper sludge was carbonate. When temperatures were 500 and 700 degrees C. the main fraction of thermally treated simulated copper sludge was also carbonate. The percentage of Fe-Mn oxides and residue increased when T = 900 degrees C. Electron Spectroscopy for Chemical Analysis (ESCA) showed that the possible Cu species of raw simulated copper sludge was Cu(OH)(2). The main possible Cu species of thermally treated simulated copper sludge were CuO and Cu2O when T was 500 and 700 degrees C, respectively. CuO, Cu2O, and Cu3O2 were the possible Cu species in thermally treated simulated copper sludge when T = 900 degrees C. (C) 2010 Elsevier B.V. All rights reserved.