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Journal of Applied Electrochemistry

, Volume 24, Issue 2, pp 157–165 | Cite as

Electrochemical stripping of gold from Au-Ni-Cu electronic connector scrap in an aqueous solution of thiourea

  • J. -C. Lin
  • J. -J. Huarng
Papers

Abstract

The electrochemical behaviour of a gold-plated connector from electronic scrap in aqueous thiourea solution has been investigated. An attempt was made to recover gold from scrap in a nontoxic thiourea medium by an electrochemical method rather than the traditional cyanide process. Linear sweep voltammetry indicated that thiourea extraction of gold is more efficient in acidic solution than in neutral and alkaline. Hydrochloric acid is preferable to control the pH of the solutions; the optimum concentration of thiourea is 2.5% (0.33 m). Analysis of voltammetric data yielded a critical potential (0.40 V vs SCE), which is the upper limit for significant extraction of gold from scrap. Higher potentials should be avoided in practice to prevent decomposition of thiourea and its passivation of the scrap. Electrolysis at constant potential indicated that gold was extracted selectively in the range 0.20–0.30 V vs SCE. Electrolysis at potentials either less than 0.15 V vs SCE or greater than 0.40 V vs SCE is not recommended, because of slow dissolution in the former and severe passivation in the latter.

Keywords

Cyanide Hydrochloric Acid Thiourea Electrochemical Behaviour Electrochemical Method 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. [1]
    G. Deschënes, CIM Bull. 79(895) (1986) 76.Google Scholar
  2. [2]
    I. N. Plaskin and M. A. Kozhukhova, Dokl. Akad. Nauk. Az. SSR 31 (1941) 671.Google Scholar
  3. [3]
    I. N. Plaskin and M. A. Kozhukhova, Sb. Nauch. Tr. Ins. Tsvt. Met. 33 (1960) 107.Google Scholar
  4. [4]
    T. Groenewald, Hydrometallurgy 1 (1976) 277.Google Scholar
  5. [5]
    J. B. Hisky, ‘Thiourea as a Lixivant for Gold and Silver’, in ‘Gold and Silver: Leaching, Recovery and Economics’, (edited by W. J. Schlitt, W. C. Larson and J. B. Hiskey), SME-AIME Littleton CO, (1981) pp. 83–91.Google Scholar
  6. [6]
    W. R. Charley, ‘Hydrometallurgical Extraction of Precious Metals Using Thiourea. Pract. Hydromet '83, Annual Symposium on Uranium and Precious Metals, 7th 1983 (CO Section Soc. Min. Eng., AIME), Lakewood, CO, 22–24 Aug. (1983) pp. 75–81.Google Scholar
  7. [7]
    J. B. Hisky, Min. Metall. Proc. 11 (1984) 174.Google Scholar
  8. [8]
    T. Groenewald, J. Appl. Electrochem. 5 (1975) 71.Google Scholar
  9. [9]
    V. P. Kazakov, A. I. Lapskin and B. I. Peshchevitskii, Russ. J. Inorg. Chem. 9(5) (1964) 708.Google Scholar
  10. [10]
    R. A. Pyper and J. L. Hendrix, ‘Extraction of Gold from Finely Disseminated Gold Ores by Use of Acidic Thiourea Solution’, Extractive Metallurgy '81, The Institution of Mining and Metallurgy, London (1981) pp. 57–75.Google Scholar
  11. [11]
    A. Lewis, ‘Thiourea: a Potential Alternative for Au/Ag Leaching’, Eng. Min. J., Feb. (1982) p. 59.Google Scholar
  12. [12]
    P. J. Van Staden and P. A. Laxen, J. South Afr. Inst. Min. Metall. 89(8), (1989) 221.Google Scholar
  13. [13]
    N. Ezawa, ‘Recovery of Precious Metals in Japan’, in Proceedings of the Second Symposium on Recovery, Refining and Reclamation of Precious Metals, (edited by G. Foo and M. E. Browning). The International Precious Metals Institute, 10–13 March (1981) Sheraton Harbour Island, Sun Diego, CA, No. 18.Google Scholar
  14. [14]
    G. Edson, ‘Recovery of Precious Metals from Electronic Scrap’, in Proceedings of the Second Symposium on Recovery, Refining and Reclamation of Precious Metals, (edited by G. Foo and M. E. Browning). The International Precious Metals Institute, 10–13 March (1981) Sheraton Harbour Island, San Diego, CA, 1981, No. 8.Google Scholar
  15. [15]
    A. S. Kulenov, A. I. Andreev, G. L. Pashkov, A. M. Kopanev, V. I. Belevantsev and V. A. Fedorov, Zh. Neorg. Khim. 28(9), (1983) 2418; CA 99: 182446z.Google Scholar
  16. [16]
    R. A. Pyper and J. L. Hendrix, ‘Extracton of Gold from a Carlin-Type Ore Using Thiourea’, in ‘Gold and Silver: Leaching, Recovery and Economics’, (edited by W. J. Schlitt, W. C. Larson and J. B. Hiskey), SEM-AIME (1981) pp. 93–108.Google Scholar
  17. [17]
    P. C. Gupta, Z. Anal. Chem. 196 (1963) 412; CA: 59: 13326b.Google Scholar
  18. [18]
    P. W. Preisler and L. Berger, J. Am. Chem. Soc. 69 (1947) 322.Google Scholar
  19. [19]
    T. Groenewald, J. South Afr. Inst. Min. Metall. 77(6), (1974) 217.Google Scholar
  20. [20]
    V. V. Lodeischchikov, A. F. Panchenko and L. N. Briantseva, Nauch. Tr. Irkutsk. Gos. Nauch. Issled. Inst. Reak. Tsvet. Metal 19 (1968) 72.Google Scholar
  21. [21]
    R. G. Sandberg and J. L. Huiatt, J. Met. June (1986) 18.Google Scholar
  22. [22]
    J. C. Huyhua and I. H. Gundiler, ‘Kinetics of Leaching Gold and Silver in Acidic Thiourea Solutions’, in Proceedings of Hydrometallurgical Reactor Design and Kinetics, (edited by R. G. Bautista, R. J. Weseley and G. W. Warren). The Metallurgical Society Annual Meeting, New Orleans, Louisiana, 2–6 March (1986) pp. 247–264.Google Scholar
  23. [23]
    J. A. Eisele, A. H. Hunt and D. L. Lampshire, ‘Leaching Gold-Silver Ores with Sodium Cyanide and Thiourea under Comparable Conditions’, Report of Investigation 9181 (1988), US Department of The Interior, Bureau of Mines.Google Scholar
  24. [24]
    R. G. Schulze, J. Met. June (1984) 62.Google Scholar

Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • J. -C. Lin
    • 1
  • J. -J. Huarng
    • 1
  1. 1.Department of Mechanical EngineeringNational Central UniversityChung-Li, TaiwanRepublic of China

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