Recovery of Gold and Silver and Removal of Copper, Zinc and Lead Ions in Pregnant and Barren Cyanide Solutions


Over the past decade the concern about toxic metals in freshwater has increased. Environmental laws such as the Clean Water Act have forced industries that produce metal containing wastewater to treat their wastewater prior to discharge. The purpose of this study was to investigate the use of a novel method for the minimization of heavy metals in the wastewater from the mining industry. A very promising electrochemical treatment technique that does not require chemical additions is electrocoagulation (EC) and sulphide precipitation. The present study has been done for the recovery of gold and silver contained in pregnant solution from the cyanidation process using the electrocoagulation technology with iron electrodes; that is a developed alternative technology for the Merril-Crowe process. The average gold and silver content in pregnant solution was 4.27 and 283 ppm respectively and the recoveries were 92% for gold and 95% for silver, with optimum operating parameters of pH 10, residence time of 20 minutes and addition of sodium chloride of 4 gr/L. The results of precipitation process show that the elimination of lead, zinc, cooper and iron ions from the barren solution was successful, with optimum operating parameters of pH 3 and residence time of 15 minutes, and the recoveries were 99% of these ions. Finally the characterization of the solid products of gold and silver formed during the EC process with Scanning Electronic Microscope was performed. Results suggest that magnetite particles and amorphous iron oxyhydroxides (lepidocrocite) were present.

Share and Cite:

Figueroa, G. , Valenzuela, J. , Parga, J. , Vazquez, V. and Valenzuela, A. (2015) Recovery of Gold and Silver and Removal of Copper, Zinc and Lead Ions in Pregnant and Barren Cyanide Solutions. Materials Sciences and Applications, 6, 171-182. doi: 10.4236/msa.2015.62020.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Habashi, F. (1967) Kinetics and Mechanism of Gold and Silver Dissolution in Cyanide Solution. Montana Bureau of Mines Geological Bulletin, 59, 1-42.
[2] Dai, X. and Jeffrey, M.I. (2006) The Effect of Sulphide Minerals on the Leaching of Gold in Aerated Cyanide Solutions. Hydrometallurgy, 82, 118-125.
[3] Fink, C.G. and Putnam, G.L. (1950) The Action of Sulphide Ion and for Metal Salts on the Dissolution of Gold in Cyanide Solutions. Transactions AIME, 187, 952-955.
[4] Hedley, N. and Tabachnick, H. (1968) Chemistry of Cyanidation. Mineral Dressing Notes No. 23, American Cyanamid Company, New Jersey.
[5] Brooy, S.R. and Linge, H.G. (1996) Review of Gold Extraction from Ores. Mineral Engineering, 7, 1213-1241.
[6] Habashi, F. (2005) A Short History of Hydrometallurgy. Hydrometallurgy, 79, 15-22.
[7] Parga, J.R., Gonzalez, G., Moreno, H. and Valenzuela, J.L. (2012) Thermodynamic Studies or the Strontium Adsoption on Iron Species Generated by Electrocoagulation. Desalination and Water Treatment, 37, 244-252.
[8] Martinez, G.V.F., Torres, J.R.P., Garcia, J.L.V., Munive, G.C.T. and Zamarripa, G.G. (2012) Kinetic Aspects of Gold and Silver Recovery in Cementation with Zinc Power and Electrocoagulation Iron Process. Advances in Chemical Engineering and Science, 2, 342-349.
[9] Rehman, I. and Bonfield, W. (1997) Characterization of Hydroxyapatite and Carbonated Apatite by Photo Acoustic FTIR Spectroscopy. Journal of Materials Science Materials in Medicine, 8, 1-4.
[10] Rayanaud, S., Champion, E., Bernache-Assollant, D. and Thomas, P. (2002) Characterization and Thermal Stability of Powders. Biomaterials, 23, 1065-1072.
[11] Bagotsky, V.S. (2006) Fundamentals of Electrochemistry. 2nd Edition, John Wiley & Sons, Inc., New Jersey, 44.
[12] Lapidus, G. (1995) Unsteady-State Model for Gold Cyanidation on a Rotating Disk. Hydrometallurgy, 39, 251-263.
[13] Jin, S., May, O., Ghali, E. and Deschenes, G. (1998) Investigation on the Mechanisms of the Catalytical Effect of Lead Salts on Gold Dissolution in Cyanide Solution. In: Yang, X.W., Chen, Q.Y. and He, A.P., Eds., Proceedings of Third International Conference on Hydrometallurgy, ICHM’98, International Academic Publishers, Beijing, 666-679.
[14] Mollah, M., Morkovsky, P., Gomez, J., Kesmez, M., Parga, J.R. and Cocke, D. (2004) Fundamentals, Present and Future Perspectives of Electrocoagulation. Journal of Hazardous Materials, 114, 199-210.
[15] Emamjomeh, M.M. and Sivakumar, M. (2009) Review of Pollutants Removed by Electrocoagulation and Electrocoagulation/Flotation Processes. Journal of Environmental Management, 90, 1663-1679.
[16] Zhao, X., Zhang, B.F., Liu, H.J. and Qu, J.H. (2010) Removal of Arsenite by Simultaneous Electro-Oxidation and Electro-Coagulation Process. Journal of Hazardous Materials, 184, 472-476.
[17] Senanayake, G. (2006) The Cyanidation of Silver Metal: Review of Kinetics and Reaction Mechanism. Hydrometallurgy, 81, 75-85.
[18] Ku, Y. and Jung, I.L. (2001) Photocatalytic Reduction of Cr(VI) in Aqueous Solutions by UV Irradiation with the Presence of Titanium Dioxide. Water Research, 35, 135-142.
[19] Lewis, A.E. (2010) Review of Metal Sulphide Precipitation. Hydrometallurgy, 104, 222-234.
[20] Lewis, A. and van Hille, R. (2006) An Exploration into Sulphide Precipitation Method and Its Effect on Metal Sulphide Removal. Hydrometallurgy, 81, 197-204.

Copyright © 2023 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.