Extraction of metals from waste printed circuit boards (WPCBs) in H2SO4–CuSO4–NaCl solutions

Abstract The extraction of metals from waste printed circuit boards (WPCBs) in H 2 SO 4 –CuSO 4 –NaCl leaching system was studied. The effect of initial concentration of cupric (0.5–7.5 g/L Cu 2 + ), chloride (4.7–46.6 g/L Cl − ) and temperature (20–80 °C) on the leaching of copper was investigated using response surface methodology, i.e., three-level Box–Behnken design. Extraction of other metals including Fe, Ni, Ag, Pd and Au was also determined. The importance of the main effects of the leaching parameters on the extraction of copper was found to be in the decreasing order of temperature, the initial concentration of Cu 2 + and Cl − . The findings have shown that the initial Cl − /Cu 2 + molar ratio should be maintained sufficiently high to maximise extraction of copper. However, an excessively high Cl − /Cu 2 + ratio can exert a detrimental effect on the process due to a decrease in the activity of Cu 2 + as oxidant. It was found that the highest levels of all the parameters should be selected to achieve high leaching recoveries (≥ 91%) for Cu, Fe, Ni and Ag. Under these conditions, the dissolution of palladium was limited to 58%. The effect of solids ratio (1–15% w/v) and air/oxygen (2–4 L/min) on the rate and extent of leaching were also tested. Increasing the solids ratio (1–15 w/v) was observed to adversely affect the leaching of metals with no copper extraction at ≥ 10 w/v in the absence of air/oxygen. Air/oxygen was confirmed to be a suitable oxidant to regenerate Cu 2 + and hence, maintain high Cu 2 + /Cu + ratios, i.e., redox potentials during the leaching process. The presence of air/oxygen led to a significant improvement in the leaching of metals, e.g., %14 Cu (no air/oxygen) cf. complete copper extraction at ≥ 2 L/min air/oxygen over 120 min. The current findings suggested that, particularly at high solids ratios (≥ 5% w/v), the regeneration of Cu 2 + by the introduction of air/oxygen is essential for high extraction of metals, Pd in particular.

[1]  Lifeng Zhang,et al.  Metallurgical recovery of metals from electronic waste: a review. , 2008, Journal of hazardous materials.

[2]  J. Viñals,et al.  Dissolution kinetics of metallic copper with CuSO4-NaCl-HCl , 2005 .

[3]  Lifeng Zhang,et al.  Leaching studies for metals recovery from waste printed wiring boards , 2011 .

[4]  C. Hageluken,et al.  Improving metal returns and eco-efficiency in electronics recycling - a holistic approach for interface optimisation between pre-processing and integrated metals smelting and refining , 2006, Proceedings of the 2006 IEEE International Symposium on Electronics and the Environment, 2006..

[5]  J. J. Fritz.  Solubility of cuprous chloride in various soluble aqueous chlorides , 1982 .

[6]  Paul G. Mathews,et al.  Design of Experiments with MINITAB , 2004 .

[7]  Rolf Widmer,et al.  Global perspectives on e-waste , 2005 .

[8]  Jae-chun Lee,et al.  Leaching behavior of copper using electro-generated chlorine in hydrochloric acid solution , 2006 .

[9]  G. Senanayake,et al.  Chloride processing of metal sulphides: Review of fundamentals and applications , 2003 .

[10]  M. Jeffrey,et al.  An introductory electrochemical approach to studying hydrometallurgical reactions , 2005 .

[11]  Peter C. Hayes,et al.  Process Principles in Minerals and Materials Production , 2003 .

[12]  Oladele A Ogunseitan,et al.  Leaching assessments of hazardous materials in cellular telephones. , 2007, Environmental science & technology.

[13]  G. Demopoulos.  Aqueous processing and its role in the production of inorganic materials and environmental protection , 1998 .

[14]  Ata Akcil,et al.  Aqueous metal recovery techniques from e-scrap: Hydrometallurgy in recycling , 2012 .

[15]  E. Jackson,et al.  Hydrometallurgical extraction and reclamation , 1986 .

[16]  M. Lundström.  Chalcopyrite dissolution in cupric chloride solutions , 2009 .

[17]  D. Fray,et al.  Recovery of high purity precious metals from printed circuit boards. , 2009, Journal of hazardous materials.

[18]  Gordon C.C. Yang,et al.  Environmental threats of discarded picture tubes and printed circuit boards , 1993 .

[19]  J. Proost,et al.  Recovery of precious metals from electronic scrap by hydrometallurgical processing routes , 2005 .

[20]  Eric Forssberg,et al.  Mechanical separation-oriented characterization of electronic scrap , 1997 .

[21]  Mihai Buzatu,et al.  Study on the influence of various factors in the hydrometallurgical processing of waste printed circuit boards for copper and gold recovery. , 2013, Waste management.

[22]  G. Demopoulos,et al.  The Solution Chemistry and Solvent Extraction Behaviour of Cu, Fe, Ni, Zn, Pb, Sn, Ag, As, Sb, Bi, Se and Te in Acid Chloride Solutions Reviewed from the Standpoint of PGM Refining , 1995 .

[23]  V. I. Lakshmanan,et al.  Chloride metallurgy: PGM recovery and titanium dioxide production , 2003 .

[24]  P. P. Sheng,et al.  Recovery of gold from computer circuit board scrap using aqua regia , 2007, Waste management & research : the journal of the International Solid Wastes and Public Cleansing Association, ISWA.

[25]  Zhou Ming,et al.  Enhancement of leaching copper by electro-oxidation from metal powders of waste printed circuit board. , 2009, Journal of hazardous materials.

[26]  G. Senanayake,et al.  Speciation and reduction potentials of metal ions in concentrated chloride and sulfate solutions relevant to processing base metal sulfides , 1988 .