Adsorption of gold from cyanide leaching solution onto activated carbon originating from coconut shell—Optimization, kinetics and equilibrium studies

Khosravi, Rasoul; Azizi, Asghar; Ghaedrahmati, Reza; Gupta, Vinod Kumar; Agarwal, Shilpi

doi:10.1016/j.jiec.2017.06.036

Cited by 88 publications

(30 citation statements)

References 61 publications

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“…It is also interesting to note that for Zinc chloride-800, the intra-particle diffusion model plot shows that the aurocyanide adsorption process was controlled by a combination of external mass transfer (initially represented by the steeper slope: gradient of 0.390 mg/g.min 0.5 ) and intra-particle diffusion represented by a less-steeper slope (gradient of 0.0858 mg/g.min 0.5 ) 33 . The value of intra-particle diffusion rate constant obtained for Zinc chloride-800 ( k id = 8.58 × 10 −2 mg g −1 min 0.5 ) was comparable to the rate constant reported for aurocyanide adsorption using coconut shell-derived activated carbon (8.48 × 10 −2 mg g −1 min 0.5 ) 2 . However, the mechanistic steps appear to be reversed for Zinc chloride-600, suggesting that intra-particle diffusion is more significant during the initial phase of adsorption before mass transfer effects become more pronounced.…”

Section: Discussionsupporting

confidence: 82%

“…From kinetic studies, it was shown that >95% of aurocyanide was recovered in 120 min from solution using ZnCl 2 treated granular carbon activated at 800 °C. This was higher than values obtained for activated carbon derived from coconut shell 2 . Further analysis showed that the aurocyanide sorption data was adequately described by the pseudo-second order model (R 2 > 0.99).…”

Section: Discussioncontrasting

confidence: 75%

“…In the current study, optimum adsorbent concentrations of 4.0 and 7.0 g/L were obtained for Zinc chloride-800 (98% aurocyanide uptake) and Zinc chloride-600 (97% aurocyanide uptake), respectively. These optimized adsorbent concentration values were higher than those reported for adsorption of aurocyanide (87%), using activated carbon produced from coconut shells as precursor (1.25 g/L) 2 . Furthermore, the findings suggest that higher temperatures produced activated carbon which was more effective in the adsorption of aurocyanide.…”

Section: Discussioncontrasting

confidence: 54%

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Efficient $${\boldsymbol{A}}{\boldsymbol{u}}{({\boldsymbol{C}}{\boldsymbol{N}})}_{{\bf{2}}}^{-{\bf{1}}}$$ adsorption using peach stone-derived granular activated carbon

Maponga

Mahamadi

2019

Sci Rep

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Agricultural wastes have attracted attention as alternative precursors for the production of granular activated carbon. Using batch sorption studies, we demonstrated that granular activated carbon prepared through chemical activation using zinc chloride followed by physical activation in nitrogen environment at high temperatures can effectively adsorb aurocyanide from solution. Furthermore, gold recovery process using the granular activated carbon was amenable to optimization of adsorption parameters such as carbon dosage, initial aurocyanide concentration and contact time. These results may open new fronts on the application of low-cost granular activated carbon, particularly in the carbon-in-pulp metallurgical process.

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Section: Discussionsupporting

confidence: 82%

Section: Discussioncontrasting

confidence: 75%

Section: Discussioncontrasting

confidence: 54%

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Efficient $${\boldsymbol{A}}{\boldsymbol{u}}{({\boldsymbol{C}}{\boldsymbol{N}})}_{{\bf{2}}}^{-{\bf{1}}}$$ adsorption using peach stone-derived granular activated carbon

Maponga

Mahamadi

2019

Sci Rep

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“…The gold leaching agent NaCN and the Au element can form a stable complex [Au(CN) 2 ] − during gold leaching [42,43]. Tan et al [5] proposed that [Au(CN) 2 ] − could be adsorbed by graphite resulting in the loss of gold, called "preg-robbing".…”

Section: Adsorption Configuration Analysis Of [Au(cn) 2 ] − On Graphimentioning

confidence: 99%

[Au(CN)2]—Adsorption on a Graphite (0001) Surface: A First Principles Study

Zhang

Xie

et al. 2018

Minerals

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Gold is mainly present in the form of [Au(CN)2]− during the cyanide leaching process, and this [Au(CN)2]− can be adsorbed by graphite in carbonaceous gold ore resulting in preg-robbing gold. In order to clarify the adsorption mechanism between the [Au(CN)2]− and graphite, the interaction between the [Au(CN)2]− and graphite (0001) surface was studied using density functional theory (DFT). The distance between [Au(CN)2]− and graphite (0001) decreased from (4.298–4.440 Å) to (3.123–3.343 Å) after optimization, and the shape of [Au(CN)2]− and graphite (0001) obviously changed from straight to curved, which indicated that the [Au(CN)2]− had been adsorbed on the graphite (0001) surface. A partial densities of state (PDOS) analysis revealed that there was little change in the delocalization and locality of the PDOS on the graphite (0001) surface after adsorption. However, the valence bands of the Au 5d orbital, C 2p orbital, and N 2p orbital near the Fermi level moved slightly towards lower energy levels; therefore, the adsorption configuration was stable. An analysis of the Mulliken charge population indicated that the Au, N, and C in [Au(CN)2]− obtained 0.26, 0.18, 0.04 electrons after adsorption, respectively, while C(surf) lost 0.03 electrons. [Au(CN)2]− changed to a conductor from an insulator after adsorption. Taking into account the surface electrical properties of [Au(CN)2]− and graphite (0001), there was still a slight electrostatic adsorption between them. The analysis of adsorption energy, electronic structure, PDOS, electron density, Mulliken charge population, and Mulliken bond population revealed that [Au(CN)2]− could be adsorbed to the graphite (0001) surface; the adsorption was a type of physical adsorption (including electrostatic adsorption) and mainly occurred on the two C≡N. These results contributed to the understanding of the mechanisms involved in preg-robbing gold formation by graphite and the optimization of this process during cyanide leaching.

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“…[4][5][6][7][8] Other applications of adsorption include heterogeneous catalysis, waste water treatment, removal of objectionable odor and taste; metal leaching, storage of logistically important gases like hydrogen and methane, molecular separations and molecular gas sensosrs. [9][10][11][12][13][14][15][16][17][18][19][20][21] In biological systems, adsorption equilibrium characterizes the ligand-binding systems. 22 Another important application of adsorption is the removal of pollutants from an unmanageable, large volume of liquid to a manageable solid phase using low cost adsorbents which are safely disposed of after the process.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

et al. 2019

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Adsorption of gold from cyanide leaching solution onto activated carbon originating from coconut shell—Optimization, kinetics and equilibrium studies

Cited by 88 publications

References 61 publications

Efficient $${\boldsymbol{A}}{\boldsymbol{u}}{({\boldsymbol{C}}{\boldsymbol{N}})}_{{\bf{2}}}^{-{\bf{1}}}$$ adsorption using peach stone-derived granular activated carbon

Efficient $${\boldsymbol{A}}{\boldsymbol{u}}{({\boldsymbol{C}}{\boldsymbol{N}})}_{{\bf{2}}}^{-{\bf{1}}}$$ adsorption using peach stone-derived granular activated carbon

[Au(CN)2]—Adsorption on a Graphite (0001) Surface: A First Principles Study

Characterization of the adsorption site energies and heterogeneous surfaces of porous materials

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