Effect of carbonate ions on pyrite (FeS2) dissolution

Descostes, Michaël; Beaucaire, Catherine; Mercier, Florence; Savoye, S.; Sow, Joachim; Zuddas, Paola

doi:10.2113/173.3.265

Cited by 79 publications

(65 citation statements)

References 13 publications

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“…The current augmentation obtained in the sulfate-carbonate system confirms that carbonates enhance the dissolution rate of the oxidative processes of arsenopyrite. Such a finding is in agreement with previous investigations (Kim et al 2000;Déscostes et al 2002;Caldeira et al 2003Caldeira et al , 2010 and cyclic voltammetry results (Fig. 6).…”

Section: Chronoamperometrysupporting

confidence: 94%

“…Likewise, the similarity in the reduction processes for both systems suggests that the arsenopyrite dissolution is promoted in the presence of carbonates, when compared to a single sulfate bath. This finding agrees with leaching experiments conducted in neutralalkaline carbonated solutions, demonstrating that the kinetics of SM was increased in the presence of these ions (Nicholson et al 1988(Nicholson et al , 1990Ciminelli and Osseo-Asare 1995;Déscostes et al 2002;Hossner and Doolittle 2003;Caldeira et al 2010). The enhancement of SM oxidation has been attributed to the formation of surface Fe and/or As carbonate complexes, which enable the leaching processes (Ciminelli and OsseoAsare 1995; Kim et al 2000;Caldeira et al 2010).…”

Section: Cyclic Voltammetrysupporting

confidence: 90%

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Arsenopyrite weathering under conditions of simulated calcareous soil

Lara¹,

Velázquez²,

Vazquez‐Arenas³

et al. 2015

Environ Sci Pollut Res

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Mining activities release arsenopyrite into calcareous soils where it undergoes weathering generating toxic compounds. The research evaluates the environmental impacts of these processes under semi-alkaline carbonated conditions. Electrochemical (cyclic voltammetry, chronoamperometry, EIS), spectroscopic (Raman, XPS), and microscopic (SEM, AFM, TEM) techniques are combined along with chemical analyses of leachates collected from simulated arsenopyrite weathering to comprehensively examine the interfacial mechanisms. Early oxidation stages enhance mineral reactivity through the formation of surface sulfur phases (e.g., S n (2-)/S(0)) with semiconductor properties, leading to oscillatory mineral reactivity. Subsequent steps entail the generation of intermediate siderite (FeCO3)-like, followed by the formation of low-compact mass sub-micro ferric oxyhydroxides (α, γ-FeOOH) with adsorbed arsenic (mainly As(III), and lower amounts of As(V)). In addition, weathering reactions can be influenced by accessible arsenic resulting in the formation of a symplesite (Fe3(AsO4)3)-like compound which is dependent on the amount of accessible arsenic in the system. It is proposed that arsenic release occurs via diffusion across secondary α, γ-FeOOH structures during arsenopyrite weathering. We suggest weathering mechanisms of arsenopyrite in calcareous soil and environmental implications based on experimental data.

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Section: Chronoamperometrysupporting

confidence: 94%

Section: Cyclic Voltammetrysupporting

confidence: 90%

Arsenopyrite weathering under conditions of simulated calcareous soil

Lara¹,

Velázquez²,

Vazquez‐Arenas³

et al. 2015

Environ Sci Pollut Res

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“…The presence of the vibration bands in Figure 9 are consistent with those identified in the FTIR spectra of the leaching liquors of the mineral concentrate with thiosulfate [20]. In Figure 10 the presence of the thiosulfate ion contained in the leaching liquors at different temperatures is shown.…”

Section: Discussionsupporting

confidence: 76%

Influence of Temperature on the Formation of Ag Complexed in a S2O32−–O2 System

et al. 2017

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Metallic elements of higher economic value, occurring in the mineralogy of Zimapán, are Pb, Zn, Cu, and Fe; said elements are sold as concentrates, which, even after processing, generally include significant concentrations of Mo, Cd, Sb, Ag, and As that can be recovered through different leaching methods. In this work, the influence of temperature in the complexation of silver contained in a concentrate of Zn using the technology of thiosulfate with oxygen injection was studied. Chemical and mineralogical characterization of the mineral concentrate from the state of Hidalgo, Mexico confirmed the existence of silver contained in a sulfide of silver arsenic (AgAsS 2 ) by X-ray Diffraction (XRD). The results obtained by Atomic Absorption Spectrophotometry (AAS) reported abundant metallic contents (% w/w) (48% Zn, 10.63% Fe, 1.97% Cu, 0.84% Pb, 0.78% As, and 0.25% Ag). These results corroborate the presence of metallic sulfides such as pyrite, chalcopyrite, and wurtzite; this last species was identified as the matrix of the concentrate by X-ray Diffraction (XRD) and Scanning Electron Microscopy-Energy-Dispersive X-ray Spectroscopy (SEM-EDS). Pourbaix diagrams were constructed for the AgAsS 2 -S 2 O 3 2− -O 2 system at different temperatures, which allowed the chemical reaction of leaching to be established, in addition to determining Eh-pH conditions in which to obtain silver in solution. The highest recoveries of the precious metal (97% Ag) were obtained at a temperature of 333 K and [S 2 O 3 2− ] = 0.5 M. The formation of silver dithiosulfate complex (Ag(S 2 O 3 ) 2 3− ) was confirmed by the characterization of the leach liquors obtained from the experiments performed in the temperature range of 298 to 333 K using Fourier transform infrared spectroscopy (FTIR).

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“…Differences in proton concentration among lake sites could be due to variations in oxidation of pyrite or variations in the presence of limestones or carbonate ions at different position of the lake which neutralizes acid production [37] [39]. The lower alkalinity was probably due to the intense oxidation of pyrite or used to neutralize acid ions.…”

Section: Spatial Variation In Chemical Compositionsmentioning

confidence: 99%

Controls on Gosaikunda Lake Chemistry within Langtang National Park in High Himalaya, Nepal

Bhatt¹,

Bhatt²,

Gaye³

2014

IJG

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Surface water samples and lake bed sediments were collected and analyzed from Gosaikunda Lake within Langtang National Park (28˚05'N, 85˚25'E; 4380 m a.s.l.) in the central Himalayan region of Nepal during fall 2011. The major cations and anions in equivalents were present in the following order:, respectively. Sulfide oxidation coupled with carbonate dissolution and aluminosilicate dissolution appeared to be the dominant geochemical processes determining lake water dissolved ions. Sulfate concentration was much higher than the alkalinity which is in contrast to glacier meltwater within the same landscape. Alkalinity primarily as bicarbonate contributes 88.6% to the total dissolved inorganic carbon (DIC) followed by carbon dioxide (CO 2 ) and carbonate (CO 3 ) in surface water samples. Organic carbon contributes 0.3% to 5.4% to the sediments and the organic matter is predominantly of aquatic origin. The lake is under saturated with carbon dioxide and the average partial pressure of carbon dioxide (pCO 2 ) appeared quite low (43.4 µatm). Overall, natural biogeochemical processes regulate the chemical species within the lake ecosystem. The lake is oligotrophic, however, nutrients and dissolved organic carbon (DOC) concentrations are enhanced at the near shore sites close to the tracking trail.

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Effect of carbonate ions on pyrite (FeS2) dissolution

Cited by 79 publications

References 13 publications

Arsenopyrite weathering under conditions of simulated calcareous soil

Arsenopyrite weathering under conditions of simulated calcareous soil

Influence of Temperature on the Formation of Ag Complexed in a S2O32−–O2 System

Controls on Gosaikunda Lake Chemistry within Langtang National Park in High Himalaya, Nepal

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