The characteristics of gold open circuit potential in ferric chloride leaching

S. Seisko, J. Aromaa, M. Lundström*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Abstract

Gold dissolution was investigated in ferric chloride media, promoted as one of the most promising alternatives for cyanide-free gold leaching. The characteristics of gold open circuit potential (OCP) and its relation to gold dissolution rate was investigated. Furthermore, the reaction mechanism of gold dissolution in ferric chloride leaching was discussed. The effect of solution variables, [Fe3+] = 0.02-1.0 M, [Cl-] = 2-5 M, T = 25-95 °C and pH = 0-1.0, on OCP and dissolution rate were studied electrochemically using rotating disk electrode (RDE) and linear polarization resistance (LPR) method with ωcyc = 1000 RPM. The investigated gold OCPs in ferric chloride solutions were found to vary between 597 and 688 mV vs. saturated calomel electrode (SCE) and gold dissolution rates between 1.2·10-5-5.0·10-4 mol s-1 m-2. Increase in temperature (25-55 °C) and ferric concentration (0.02-1.0 M) changed OCP into more positive values, while increase in chloride concentration (2-5 M) decreased it. The logarithm of gold dissolution rate was shown to increase linearly with increasing OCP at the temperature range 25-95 °C, ferric concentration range 0.02-0.5 M and chloride concentration range 2-4 M. A notable increase in the gold dissolution reaction rate was evident at T > 55 °C.

Original languageEnglish
Title of host publicationIMPC 2018 - 29th International Mineral Processing Congress
PublisherCanadian Institute of Mining, Metallurgy and Petroleum
Pages2723-2730
Number of pages8
ISBN (Electronic)9787030227119
ISBN (Print)9781510874992
Publication statusPublished - 1 Jan 2019
MoE publication typeA4 Article in a conference publication
EventInternational Mineral Processing Congress - Moscow, Russian Federation
Duration: 17 Sep 201821 Sep 2018
Conference number: 29

Conference

ConferenceInternational Mineral Processing Congress
Abbreviated titleIMPC
CountryRussian Federation
CityMoscow
Period17/09/201821/09/2018

Keywords

  • Cyanide-free gold leaching
  • Open circuit potential
  • Process parameters
  • Sustainable

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