Feasibility of copper leaching from an industrial sludge using ammonia solutions

Feasibility study on the recovery of copper from an industrial sludge was conducted. The petrochemical sludge containing high concentration of copper was characterized utilizing X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (ESCA), Sequential extraction was used to determine the chemical forms of copper in the sludge. To leach copper from the sludge, aqueous ammonia solution was used. The leaching reaction was completed within 6 h. Best leaching efficiency (ca, 94%) was found at pH of 10, Higher solid-liquid ratio and higher temperature could enhance the leaching reaction. Results of the copper speciations in the leached sludge show that copper was mainly leached from both the organic-bound and residual fractions. Results suggested that the ammonia-leaching technique is full of potential in metal recovery from industrial sludges. (C) 1998 Elsevier Science B.V.