Journal of Sustainable Metallurgy

, Volume 4, Issue 2, pp 265–275 | Cite as

Screening of Non-cyanide Leaching Reagents for Gold Recovery from Waste Electric and Electronic Equipment

  • Alexander BirichEmail author
  • Seifeldin Raslan Mohamed
  • Bernd Friedrich
Innovations in WEEE Recycling
Part of the following topical collections:
  1. Innovations in WEEE Recycling


The importance of gold recycling from waste electronic and electrical equipment (WEEE) is continuously increasing due to raising gold demand and the need for new recycling methods for this complex waste. In state-of-the art processes gold is recovered in the copper route. In necessary pre-treatment steps, a significant loss of gold occurs. Furthermore, in this process the gold is bound for a longer time period in a copper phase and is separated in a mixture with other noble metals, which needs further treatment. A direct gold extraction from WEEE by selective leaching and precipitation would have many advantages. Due to raising social awareness of the ecological impacts of cyanidic gold extraction and environmental specifications, cyanide cannot be used as gold extractant in modern processes. Therefore, over the course of this study, two experimental sets have been conducted on each of six non-cyanide leaching reagents to test their feasibility and compare them against each other. Aqua regia and iodine/iodide leaching systems were the most successful reagents, yielding 100% of gold while showing very fast leaching rates. A comparison between the two successful reagents was carried out, with the results favoring iodine leaching due to its high selectivity for precious metals and reduced environmental impact.


Gold Leaching Cyanide alternative reagents WEEE recycling Electronic scrap Cyanide-free Iodine Thiourea Thiosulfate MSA LSSS 


  1. 1.
    Baldé C et al (2015) The global E-waste monitor—2014. United Nations University, BonnGoogle Scholar
  2. 2.
    Akcil A et al (2015) Precious metal recovery from waste printed circuit boards using cyanide and non-cyanide lixiviants—a review. Waste Manag 45:258–271CrossRefGoogle Scholar
  3. 3.
    Zhang L, Xu Z (2016) A review of current progress of recycling technologies for metals from waste electrical and electronic equipment. J Clean Prod 127:19–36CrossRefGoogle Scholar
  4. 4.
    Tuncuk A et al (2011) Aqueous metal recovery techniques from E-scrap: hydrometallurgy in recycling. Miner Eng 25(1):28–37CrossRefGoogle Scholar
  5. 5.
    Kasper et al (2015) Electronic waste: recycling techniques (Chapter 9). Springer, ChamGoogle Scholar
  6. 6.
    Norgate T, Haque N (2012) Using life cycle assessment to evaluate some environmental impacts of gold production. Elsevier 29–30:53–63Google Scholar
  7. 7.
    Montero R et al (2012) Recovery of gold, silver, copper and niobium from printed circuit boards using leaching column technique. J Earth Sci Eng 2:590–595Google Scholar
  8. 8.
    Silver Processing, Encyclopedia Britannica. Accessed 11 Aug 2016
  9. 9.
    Environmental Protection Agency (EPA) (2010) Toxicological review of hydrogen cyanide and cyanide saltsGoogle Scholar
  10. 10.
    Mineral Commodity Summaries (2012) Gold production in world, George US Geological SurveyGoogle Scholar
  11. 11.
    Marsden K, House I (2006) The chemistry of gold extraction. SME, LittletonGoogle Scholar
  12. 12.
    Syed S (2012) Recovery of gold from secondary sources: a review. Hydrometallurgy 115–116:30–51CrossRefGoogle Scholar
  13. 13.
    Zhang Y et al (2012) Current status on leaching precious metals from waste printed circuit boards. Procedia Environ Sci 16:560–568CrossRefGoogle Scholar
  14. 14.
    Park Y, Fray D (2009) Recovery of high purity precious metals from printed circuit boards. J Hazard Mater 164:1152–1158CrossRefGoogle Scholar
  15. 15.
    Sheng P, Etsell T (2007) Recovery of gold from computer circuit board scrap using aqua regia. Waste Manag Res 25:380–383CrossRefGoogle Scholar
  16. 16.
    Sahin M et al (2015) A potential alternative for precious metal recovery from E-waste: iodine leaching 50:2587–2595Google Scholar
  17. 17.
    Baghalha M (2012) The leaching kinetics of an oxide gold ore with iodide/iodine solutions. Hydrometallurgy 113–114:42–50CrossRefGoogle Scholar
  18. 18.
    Chen L et al (2009) Iodine leaching process for recovery of gold from waste PCB. Chin J Environ Eng 3:911–914Google Scholar
  19. 19.
    Wang H et al (2013) Study on gold concentrate leaching by iodine-iodide. Int J Miner Metall Mater 20:323–328CrossRefGoogle Scholar
  20. 20.
    Melashvili M, Manimaran M (2014) Study of gold leaching with bromine and bromide and the influence of suphide minders on this reaction. In: Conference of metallurgists proceedings 2014Google Scholar
  21. 21.
    Tripathi A et al (2012) Leaching of gold from the waste mobile phone printed circuit boards (PCBs) with ammonium thiosulfate. Int J Metall Eng 1:17–21Google Scholar
  22. 22.
    Ying L, Li X (2011) Thiosulfate leaching of gold and silver from waste mobile phones. In: International conference on bioinformatics and biomedical engineering 2011Google Scholar
  23. 23.
    Li J, Miller D (2007) Reaction kinetics of gold dissolution in acid thiourea solution using ferric sulfate as oxidant. Hydrometallurgy 89:279–288CrossRefGoogle Scholar
  24. 24.
    Huyhua J et al (1989) A comparative study of oxidants on gold and silver dissolution in acidic thiourea solutions. In: Proceedings of the Minerals, Metals and Materials Society, 1989Google Scholar
  25. 25.
    Zhang W et al (2016) Mechanism and clean procedure to extract gold from printed circuit board. Procedia Environ Sci 31:171–177CrossRefGoogle Scholar
  26. 26.
    Wu J et al (2009) Gold and silver selective leaching from printed circuit boards scrap with acid thiourea solution. Nonferrous Metals 61:90–93Google Scholar
  27. 27.
    Zhong F et al (2006) Experimental study on leaching gold in printed circuit boards scrap with thiourea. Non-Ferrous Metals Recycl Util 6:25–27Google Scholar
  28. 28.
    Wu J et al (2008) Study on selectively leaching gold from waste printed circuit boards with thiourea. Chin J Gold 6:55–58Google Scholar
  29. 29.
    Gernon M (1996) Preparation of a precious metal salt of a non-oxidizing acid by direct reaction. European Patent Application, EP0711753A1Google Scholar
  30. 30.
    Gernon M et al (1999) Environmental benefits of methanesulfonic acid: comparative properties and advantages. Green Chem 1:127–140CrossRefGoogle Scholar
  31. 31.
    Zhang J, Lan Z (1992) Leaching gold and silver by the LSSS method—Part I. synthesizing the LSSS and dissolving Au and Ag. In: International Conference-Proceeding Precious Metals, 1992Google Scholar
  32. 32.
    Zhao L et al (2015) Effects of lime sulfur synthetic solution on leaching characteristic of gold concentrates. Chin J Nonferrous Met 25:786–792Google Scholar
  33. 33.
    Ying L, Lu H (2010) The leaching of gold and silver from E-waste by LSSS method. Waste Manag 32:1209–1212CrossRefGoogle Scholar
  34. 34.
    Aylmore M, Muir D (2001) Thiosulfate leaching of gold—a review. Miner Eng 14:135–174CrossRefGoogle Scholar

Copyright information

© The Minerals, Metals & Materials Society 2018

Authors and Affiliations

  1. 1.Institute of Process Metallurgy and Metal RecyclingRWTH-Aachen UniversityAachenGermany

Personalised recommendations