A review of thiocyanate gold leaching – Chemistry, thermodynamics, kinetics and processing

Azizitorghabeh, Atefeh; Wang, Jingxiu; Ramsay, J. O.; Ghahreman, Ahmad

doi:10.1016/j.mineng.2020.106689

Cited by 44 publications

(18 citation statements)

References 47 publications

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“…− is formed at a lower rate, leading to the adsorption of AuSCN [Au(s) + SCN − ] and gradual formation of a stable passive layer of AuSCN on the gold surface, decreasing the gold dissolution rate. 6,14 The total iron concentration decreased rapidly during the first 3 h of leaching and then plateaued (Figure 5). This change was driven by the reduction of Fe 3+ to Fe 2+ early in the leaching process.…”

Section: Statistical Evaluation and Processmentioning

confidence: 99%

“…Therefore, the leaching process more likely follows a diffusion-controlled model, which is consistent with the literature. 6,21 The thiocyanate gold leaching process seems to have three stages. The initial leaching stage is when the solution potential is high, and Au(SCN) 4 − is produced rapidly.…”

Section: Rate-controllingmentioning

confidence: 99%

“…− is produced moderately and results in the formation of a stable passivation layer of AuSCN [Au(s) + SCN − ] on the gold surface in the final stage of leaching. 6,9,14 The passive layer of the latter stage limits the diffusion of species to and from the gold surfaces. Consequently, diffusion of the leaching agent through the passivation layer is assumed as the rate-controlling step in the system.…”

Section: Rate-controllingmentioning

confidence: 99%

“…6 Moreover, thiourea had been employed for gold leaching from the stibnite concentrate in the New England Antimony mine, New South Wales, and also from the copper concentrate in the Val d'Or Mine, Quebec. 6 Thiourea and thiocyanate have not yet made any significant inroads in the gold mining industry. Compared with that of thiourea and thiosulfate, thiocyanate consumption in gold leaching is lower, which is cost-effective, and it has better stability than thiourea in various media and is 0.1% as toxic as cyanide.…”

Section: Introductionmentioning

confidence: 99%

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Gold Leaching from an Oxide Ore Using Thiocyanate as a Lixiviant: Process Optimization and Kinetics

et al. 2021

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Thiocyanate (SCN–) is a promising alternative to cyanide as a lixiviant for gold extraction and is 1000 times less toxic than cyanide. In this study, the following leaching parameters were tested to optimize the gold recovery for the first time from an oxide ore using the response surface methodology: initial thiocyanate concentration (10–500 mM), initial Fe3+ concentration (10–500 mM), and pulp density (10–50% w/v). The maximum gold recovery (96%) was achieved with 500 mM thiocyanate, 100 mM Fe3+, and 50% pulp density at 25 °C and pH = 2 for 24 h. A kinetic study on the optimum leaching condition showed that it followed the shrinking core model, in which the rate-controlling mechanism was the diffusion process. These results are discussed in the context of the published literature.

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Section: Statistical Evaluation and Processmentioning

confidence: 99%

Section: Rate-controllingmentioning

confidence: 99%

Section: Rate-controllingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gold Leaching from an Oxide Ore Using Thiocyanate as a Lixiviant: Process Optimization and Kinetics

et al. 2021

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“…The U.S. Bureau of Mines uses statistical experimental methods to determine the feasibility of thiosulfate leaching [7]. Up to 62% gold extraction rate can be obtained from the thiosulfate leaching of low-grade carbonaceous ore, and it has been successfully applied at Goldstrike mine, Nevada, of Barrick Gold Corp [8]. In addition, glycine leaching has the advantages of a simple process, stability in a wide Eh-pH range, easy recovery and nontoxicity, which attracted the interest of researchers.…”

Section: Introductionmentioning

confidence: 99%

Recovery of Gold from Ore with Potassium Ferrocyanide Solution under UV Light

et al. 2021

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In this study, potassium ferrocyanide, a nontoxic cyanide precursor in dark and diffuse reflection environment, was applied as reagent for the leaching of gold. The free cyanide ions could gradually release from potassium ferrocyanide solution under the ultraviolet light. Orthogonal leaching experiments were performed in gold ore to analyze the effect of solution pH, potassium ferrocyanide dosage, and temperature in a potassium ferrocyanide solution system under UV light. Response surface methodology (RSM) was applied to explore the role of potassium ferrocyanide in gold leaching; optimized results showed that the gold recovery reached 67.74% in a high-alkaline environment at a 12.6 pH, 3.8 kg/t potassium ferrocyanide dosage, 62 °C, and irradiance of 10 mW·cm−2. The gold leaching kinetics were monitored by quartz crystal microbalance with dissipation (QCM-D) of potassium ferrocyanide solution. The results indicate that the gold extraction process could be divided into two stages: adsorption and leaching, and a rigid adsorption layer formed on the reaction surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis of the gold sensor surface after leaching reaction showed that –C≡N appears on the gold sensor surface, and the gold is oxidized to form AuCN complexes.

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Bionanomining: A Revised Insight into Processing of South Africa’s Complex Gold Ores

Okanigbe

Popoola

Malatji

et al. 2022

The Minerals, Metals &Amp; Materials Series

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A review of thiocyanate gold leaching – Chemistry, thermodynamics, kinetics and processing

Cited by 44 publications

References 47 publications

Gold Leaching from an Oxide Ore Using Thiocyanate as a Lixiviant: Process Optimization and Kinetics

Gold Leaching from an Oxide Ore Using Thiocyanate as a Lixiviant: Process Optimization and Kinetics

Recovery of Gold from Ore with Potassium Ferrocyanide Solution under UV Light

Bionanomining: A Revised Insight into Processing of South Africa’s Complex Gold Ores

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