The use of carbon paste electrodes with non-conducting binder for the study of minerals: Chalcopyrite

Lázaro, Isabel; Martínez-Medina, Norma; Rodríguez, Israel; Arce, E.; González, Ignacio

doi:10.1016/0304-386x(94)00070-j

Cited by 86 publications

(27 citation statements)

References 23 publications

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“…These electrodes have a main drawback of poor reproducibility. Carbon paste electroactive electrodes made of graphite, mineral powders, and non-conductive binder, however, offer distinct advantages, when they are used for the electrochemical studies of sulfide minerals [19]. These advantages [19] include excellent reproducibility because the problems of polishing deficiency and lack of homogeneity for the massive mineral electrodes are eliminated, and the ability to represent the real leaching conditions because carbon paste electrodes with nonconducting binder are electroactive only at the electrode/ electrolyte interface.…”

Section: Introductionmentioning

confidence: 98%

Influence of ferric iron on the electrochemical behavior of pyrite

Liu

Dang

et al. 2010

Ionics

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The electrochemical behavior of a pyrite electrode in a sulfuric acid solution with different concentrations of ferric iron (Fe 3+ ) was investigated using electrochemical techniques including measurements of open circuit potential, cyclic voltammetry, Tafel polarization curves and electrochemical impedance spectroscopy (EIS). The results show that the pyrite oxidation process takes place via a two-step reaction at the interface of the pyrite electrode and the electrolyte, and that a passivation film composed of elemental sulfur, polysulfides, and metal-deficient sulfide is formed during the process of the first-step reaction. Ferric iron plays an important role in the dissolution of pyrite by enhancing the direct oxidation. The Tafel polarization curves indicate that the polarization current of the pyrite electrode increases with an increase in Fe 3+ concentration. It has also been shown that the higher concentration of Fe 3+ , the more easily the pyrite can be transformed into the passivation region. Moreover, the EIS response is found to be sensitive to changes in Fe 3+ concentration.

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Section: Introductionmentioning

confidence: 98%

Influence of ferric iron on the electrochemical behavior of pyrite

Liu

Dang

et al. 2010

Ionics

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“…The CPE performance and preparation is described in Lázaro et al (1995). The usage of CPE-minerals is recommended during cyclic voltammetry and chronoamperometry in order to avoid substantial capacitive currents in electrochemical responses (e.g., Lázaro et al 1995;Cisneros-González et al 2000). Cyclic voltammetry was initiated in the positive-going direction at 20 mV·s −1 .…”

Section: Electrochemical Studymentioning

confidence: 99%

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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“…Esta reacción fue propuesta por Nava y colaboradores 16 considerando que diversos investigadores 17,18 han informado que la oxidación de calcopirita a E > 0,575 V, forma un sulfuro de cobre y hierro no estequiométrico: CuFeS 2 ⇔ Cu 1-x Fe 1-y S 2-z + xCu 2+ + yFe 2+ + zS + 2(x+y)e - (17) Además, la detección de cobre en el licor soporta esta discusión, (Figura 10a).…”

Section: Figura 10 (A) Corrientes De Los Picos De Redisolución Anódiunclassified

Los electrodos de pasta de carbono en el estudio electroquímico de minerales metálicos

Nava

González

2005

Quím. Nova

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Recebido em 29/6/04; aceito em 8/11/04; publicado na web em 28/2/05 THE ROLE OF THE CARBON PASTE ELECTRODES IN THE ELECTROCHEMICAL STUDY OF METALLIC MINERALS. This paper shows the applicability of the carbon paste electrode-mineral (CPE-mineral) to study the dissolution mechanisms of minerals in powder form and in flotation concentrates. A potentiodynamic strategy to find the dissolution mechanism of galena (PbS) is presented. In this way, minerals less studied such as orpiment (As 2 S 3 ) and realgar (As 2 S 2 ) are investigated. The electrochemical activity of a more complicated mineral such as sphalerite (ZnS), containing 12.3 and 0.43% of iron in solid solution, is discussed. The mechanism of a complex zinc concentrate (containing 63.4% ZnS, 20.1% FeS 2 , 5% CuFeS 2 , 0.33% PbS, 0.45% Cu 12 Sb 4 S 13 and 0.4% FeAsS) is described. Finally, an electrochemical method for the detection of the different leachable and refractory silver phases (contained in two mineral concentrates) is presented. This paper reviews the power of the use of CPEmineral coupled to electrochemical techniques in hydrometallurgy.Keywords: CPE-mineral; dissolution mechanisms; electrochemical techniques. INTRODUCCIÓNLos sulfuros minerales son la principal fuente para la obtención de metales base, siendo los procesos pirometalúrgicos los que han sido tradicionalmente empleados para el procesamiento de estos minerales. Sin embargo, la emisión de SO 2(gas) y de partículas sólidas suspendidas en el aire, durante la combustión, ha llevado a la búsqueda de procesos limpios, siendo la ruta hidrometalúrgica la que ha recibido especial atención 1 .Los procesos de disolución oxidativa de muchos minerales (empleando oxidantes como Fe(III), O 2 , entre otros), han presentado algunos problemas que han impedido tener eficiencias satisfactorias en la aplicación industrial 1 . Es importante mencionar que las reacciones que toman lugar en los procesos hidrometalúrgicos son de naturaleza electroquímica y por lo tanto, su entendimiento es indispensable para la optimización de estos procesos.En el estudio electroquímico de minerales, se pueden emplear cristales de mineral como electrodos de prueba. No obstante, algunos minerales presentan ciertas propiedades semiconductoras que complican su caracterización. Por otro lado, la reproducibilidad experimental que estos electrodos proporcionan no es confiable, dado que la renovación de la superficie, para cada nueva experiencia es complicada.Los electrodos de pasta de carbono-mineral (CPE-mineral), donde el mineral pulverizado es mezclado con polvo de grafito, han mostrado su conveniencia en el estudio de mecanismos de minerales. Los CPE-mineral, pueden utilizar un aglomerante conductor, que puede ser H 2 SO 4 o bien HCl 2,3 . Por otro lado, los CPEmineral pueden ser preparados con aglomerantes no conductores ya sea usando aceites orgánicos, o bien aceites minerales, los cuales suelen ser hidrofóbicos 4,5 , permitiendo que las reacciones electroquímicas sólo tomen lugar en la interfase electrodoelectrolito. Esto últ...

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The use of carbon paste electrodes with non-conducting binder for the study of minerals: Chalcopyrite

Cited by 86 publications

References 23 publications

Influence of ferric iron on the electrochemical behavior of pyrite

Influence of ferric iron on the electrochemical behavior of pyrite

Arsenopyrite weathering under conditions of simulated calcareous soil

Los electrodos de pasta de carbono en el estudio electroquímico de minerales metálicos

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