Predicting Cyanide Consumption in Gold Leaching: A Kinetic and Thermodynamic Modeling Approach

Kianinia, Yaser; Khalesi, Mohammad Reza; Abdollahy, Mahmoud; Hefter, Glenn; Senanayake, Gamini; Hnědkovský, L.; Darban, Ahmad Khodadadi; Shahbazi, Marjan

doi:10.3390/min8030110

Cited by 23 publications

(7 citation statements)

References 28 publications

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“…Cyanide dissolution of gold is described as follows This follows the electrochemical equations 39 A stock leach residue (left after leaching roasted ore at 650 °C in 20% HCl) was used for testing the gold recovery. A series of experiments were performed to assess the efficiency of gold recovery from the acid leach residue at a varied CN – concentration for 24 h. It is noticed from Figure 4 that gold recovery significantly increases with the increasing CN – concentration, reaching 93% at 0.1% CN – , leveled off and remained at this high level at higher CN – concentrations.…”

Section: Resultsmentioning

confidence: 99%

Developed Process Circuit Flowsheet of Al Amar Ore for Production of Nanocrystalline Ferrite and Improving Gold Recovery

et al. 2020

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Amar gold ore is rich in sulfides of base metals and is commercially applied for the production of copper concentrate via floatation and gold bullion by cyanidation of tailing. The current process flowsheet suffers from low gold recovery (∼60%) and loss of metals in the hazardous stockpiled residue. This work addresses these drawbacks by a newly experimental redesign of the process circuit. The innovative flowsheet comprises a sequence of operations, including acid leaching of the roasted ore, gold recovery from the leach residue, and preparation of a valuable zinc−copper−lead ferrite from the filtrate by coprecipitation followed by heat treatment. The ore is roasted at 650 °C and then leached in 20% HCl, where most of Zn, Cu, Pb, and Fe contents are dissolved, while pristine gold remains in the residue. Most of the gold (∼93%) can be recovered by cyanidation of the acid leach residue. Stoichiometric ratios of dissolved Zn, Cu, Pb, and Fe in the acid leach solution can be kept at 0.6:0.3:0.1:2.0, respectively, only by adding a small amount of ferric chloride. These metals are coprecipitated at varying pH values from 8 to 10, and the produced powders are annealed at temperatures from 600 to 1100 °C. X-ray diffraction (XRD) charts reveal sharp peaks of the targeted Zn 0.6 Cu 0.3 Pb 0.1 Fe 2 O 4 phase at 600 °C, while a highly crystalline single phase is obtained at 1100 °C, independently of precipitation pH. The crystalline size of the produced powders increases with annealing temperatures (from 18−27 nm at 600 °C to 85−105 nm at 1100 °C). The finest size is found at pH 12. Scanning electron microscopy (SEM) investigation shows uniform cubic microstructures of samples annealed at 1100 °C. The produced ferrite powders exhibit soft magnetic characteristics. Saturation magnetization, M s , substantially increases with pH. Coercivity, H c, increases with increasing annealing temperatures, from 600 to 800 °C, and decreases above 800 °C. Preliminary cost−benefit analysis revealed that the profit margin of the proposed process flowsheet is promising. The wastewater is almost free of heavy metals. Our advances in high gold recovery and preparation of valuable magnetic nanocrystalline ferrite provide exciting opportunities to enhance and maximize Al Amar ore production for practical applications.

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Section: Resultsmentioning

confidence: 99%

Developed Process Circuit Flowsheet of Al Amar Ore for Production of Nanocrystalline Ferrite and Improving Gold Recovery

et al. 2020

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“…The possible cyanide-consuming dissolution reactions of sulfide minerals are suggested in Eqs. 4-6 (Zhang et al 1997;Kianinia et al 2018):…”

Section: Cyanidationmentioning

confidence: 99%

Process simulation and gate-to-gate life cycle assessment of hydrometallurgical refractory gold concentrate processing

Elomaa

Sinisalo

Rintala

et al. 2019

Int J Life Cycle Assess

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Purpose Currently, almost all cyanide-free gold leaching processes are still in the development stage. Proactively investigating their environmental impacts prior to commercialization is of utmost importance. In this study, a detailed refractory gold concentrate process simulation with mass and energy balance was built for state-of-the-art technology with (i) pressure oxidation followed by cyanidation and, compared to alternative cyanide-free technology, with (ii) pressure oxidation followed by halogen leaching. Subsequently, the simulated mass balance was used as life cycle inventory data in order to evaluate the environmental impacts of the predominant cyanidation process and a cyanide-free alternative. Methods The environmental indicators for each scenario are based on the mass balance produced with HSC Sim steady-state simulation. The simulated mass balances were evaluated to identify the challenges in used technologies. The HSC Sim software is compatible with the GaBi LCA software, where LCI data from HSC-Sim is directly exported to. The simulation produces a consistent life cycle inventory (LCI). In GaBi LCA software, the environmental indicators of global warming potential (GWP), acidification potential (AP), terrestrial eutrophication potential (EP), and water depletion (Water) are estimated. Results and discussion The life cycle assessment revealed that the GWP for cyanidation was 10.1 t CO 2 -e/kg Au, whereas the halogen process indicated a slightly higher GWP of 12.6 t CO 2 -e/kg Au. The difference is partially explained by the fact that the footprint is calculated against produced units of Au; total recovery by the halogen leaching route for gold was only 87.3%, whereas the cyanidation route could extract as much as 98.5% of gold. The addition of a second gold recovery unit to extract gold also from the washing water in the halogen process increased gold recovery up to 98.5%, decreasing the GWP of the halogen process to 11.5 t CO 2 -e/kg Au. However, both evaluated halogen processing scenarios indicated a slightly higher global warming potential when compared to the dominating cyanidation technology. Conclusions The estimated environmental impacts predict that the development-stage cyanide-free process still has some challenges compared to cyanidation; as in the investigated scenarios, the environmental impacts were generally higher for halogen leaching. Further process improvements, for example in the form of decreased moisture in the feed for halide leaching, and the adaptation of in situ gold recovery practices in chloride leaching may give the cyanide-free processing options a competitive edge.

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“…During cyanidation minor amounts of sulfide minerals may dissolve. The dissolution reactions (Equations 6-8) of sulfide minerals are (Kianinia et al 2018;Zhang et al, 1997):…”

Section: Cyanidationmentioning

confidence: 99%

Open circuit potential and leaching rate of pyrite in cupric chloride solution

Elomaa

Rintala

Aromaa

et al. 2018

Canadian Metallurgical Quarterly

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Predicting Cyanide Consumption in Gold Leaching: A Kinetic and Thermodynamic Modeling Approach

Cited by 23 publications

References 28 publications

Developed Process Circuit Flowsheet of Al Amar Ore for Production of Nanocrystalline Ferrite and Improving Gold Recovery

Developed Process Circuit Flowsheet of Al Amar Ore for Production of Nanocrystalline Ferrite and Improving Gold Recovery

Process simulation and gate-to-gate life cycle assessment of hydrometallurgical refractory gold concentrate processing

Open circuit potential and leaching rate of pyrite in cupric chloride solution

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