Abstract:The metallic copper in electroplating sludge was leached by two leaching agents, EDTA and EDTA mixed with citric acid (EDTA+CA). The effects of EDTA concentration, ratio of CA in EDTA+CA, and temperature on leaching of copper were studied, and the leaching kinetics was analyzed. The results show that copper leaching rate by EDTA is 80.61% under the conditions including EDTA concentration of 70 mmol/L, temperature of 55 ℃, and leaching time of 3 h, while copper leaching rate by EDTA+CA is 90.32% under the conditions including 70 mmol/L EDTA + 10 mmol/L CA, temperature of 55 ℃, and leaching time of 3 h. The leaching process can be described by Avrami equation, and the apparent activation energies of EDTA and EDTA+CA leaching reactions are 43.00 and 45.74 kJ/mol, respectively. The leaching is all mixed control and dominated by surface chemical control.