Chloride hydrometallurgy

Winand, René

doi:10.1016/0304-386x(91)90055-q

Cited by 142 publications

(98 citation statements)

References 42 publications

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“…3) se producen cuando se ha lixiviado ya la mayor parte de la esfalerita y, en consecuencia, la velocidad de ataque de la fracción que resta se ha hecho comparativamente muy pequeña. Estos máximos se alcanzan cuando se igualan las velocidades de producción de ácido según la reacción [7] y de amoníaco según la reacción [4]. A partir de este momento, la concentración de amoní-aco disminuye de forma continua y progresiva, al pasar a ser mayor la velocidad de producción de ácido que la de amoníaco.…”

Section: Fig 4-nh 3 Produced Versus Zinc Leached At 100 110 Y 120 unclassified

“…[7], los resultados de ensayos efectuados a diferentes temperaturas con esfalerita de La Cavada y con el concentrado diferencial de cinc, al objeto de determinar la influencia que esta variable tiene sobre la velocidad de reacción. En el caso del concentrado diferencial de cinc, se ha utilizado la fracción granulométrica -15 +10 |xm, X ro FIG.…”

Section: Influencia De La Temperaturaunclassified

“…El medio cloruro da lugar a cinéticas de lixiviación más favorables que el medio sulfato (7). Además, la solubilidad de los cloruros es mayor, aumentando adicionalmente al crecer la concentración de cloruros (7-10) por el efecto complejante de este ion.…”

Section: Introductionunclassified

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Lixiviación oxidante de sulfuros complejos en soluciones de cloruro amónico: cinética de la lixiviación de la esfalerita

Limpo¹

1997

REVMETAL

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Lixiviación oxidante de sulfuros complejos en soluciones de cloruro amónico: cinética de la lixiviación de la esfalerita (#) J.L. Limpcr y Resumen Tras la revisión de las publicaciones recientes sobre la lixiviación de esfalerita en medio cloruro, se presentan los resultados obtenidos en el estudio de la cinética de la lixiviación oxidante con oxígeno de esfalerita en soluciones concentradas de cloruro amónico en presencia de ion cúprico. Este estudio se ha realizado sobre una esfalerita de gran pureza y un concentrado diferencial de cinc. En el intervalo de temperatura estudiado (80 a 130 °C) la disolución se produce de acuerdo con una cinética de control mixto según el modelo de "núcleo sin reaccionar", en el que tanto la difusión en la capa de azufre como la reacción química en el núcleo son etapas controlantes. La expresión matemática de este modelo es: [1-(1-X)Se ha estudiado la influencia que sobre la velocidad de reacción tiene la temperatura, tamaño de partícula y concentración de cúprico. Los valores de la energía de activación de da constante k r que se han obtenido para la esfalerita pura y el concentrado de cinc son, respectivamente, 66,4 y 67,6 kJ/mol. La velocidad de la disolución del cinc aumenta con la potencia 0,43 de la concentración de cúprico. Los resultados obtenidos de la influencia del tamaño de partícula (k T°c \/r 0 y Bocr 0 ), son los que teóricamente predice el modelo de control mixto, hecho que corrobora la validez de este modelo cinético.Palabras clave: Lixiviación. Esfalerita. Cinética. Medio cloruro amónico. Oxidizing leaching of complex sulphides in ammonium chloride: sphalerite leaching kinetics AbstractRecent studies on chloride leaching of sphalerite are rewieved. The kinetics of oxygen leaching of sphalerite in concentrated ammonium chloride solutions in the presence of cupric ion has been studied. A puré sphalerite and a zinc concéntrate have been tested. 80-130 °C temperature range, the dissolution occurred according to a mixed model which assumed both diffusion through sulfur layer and a surface reaction in the shrinking core model. This is described mathematically as: [1-(1-X)The effect of temperature, cupric concentration and particle size on the dissolution rate were determinated. The activation energy of the rate constant k r for the puré sphalerite and zinc concéntrate was found to be 66.4 and 67.6 kJ/mol respectively. The dissolution rate increased as the 0.43 power of the cupric cloride concentration. The results obtained for the effect of particle size show, such as it is predicted by the kinetic mixed model, that the rate constant k r is inversely related, and the parameter B is directly related, to particle radius.

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Section: Fig 4-nh 3 Produced Versus Zinc Leached At 100 110 Y 120 unclassified

Section: Influencia De La Temperaturaunclassified

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Lixiviación oxidante de sulfuros complejos en soluciones de cloruro amónico: cinética de la lixiviación de la esfalerita

Limpo¹

1997

REVMETAL

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“…Ferric and cupric ions, bacteria, oxygen, and other oxidants have been used as leaching agents of sulphide in sulphate and chloride media under atmospheric or pressure leaching conditions [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

“…The oxidation potential of ferric chloride leaching system results in elemental sulphur as one of the major by-products, a form generally more acceptable environmentally than the sulphur dioxide from pyrometallurgy. The leaching of metal sulphide minerals in chloride media is a subject of interest and many articles have been published [12][13][14][15][16][17][18]. This studied indicated that the ferric chloride solutions could rapidly, but unselectively leach valuable metals such as copper, zinc and lead from sulphide minerals, leaving the bulk of the pyrite and sulphur.…”

Section: Introductionmentioning

confidence: 99%

Complex sulphide-barite ore leaching in ferric chloride solution

Sokić¹,

Matković²,

Marković³

et al. 2016

Metall Mater Eng

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The results of research on the leaching process of complex sulphide-barite ore were presented in this paper. The leaching process was carried out in a laboratory autoclave by ferric chloride solution. Considering that those minerals are represented in complex structural-textural relationships, it is not possible to extract lead, zinc and copper minerals from ore by flotation methods. The obtained results confirmed possibility of the ore processing directly, by chemical methods. The effect of temperature, time and oxygen partial pressure on the lead, zinc and copper dissolution was studied. The maximal leaching degree was achieved at 100 C and amount of 91.5 % for Pb, 96.1 % for Zn and 60.7 % for Cu). Leaching at temperatures above 100 C is impractical.

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Electrodeposition of Zinc and Zinc Alloys

Winand¹

2010

Modern Electroplating

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Zinc has a standard reversible potential [À0.76 V/standard hydrogen electrode (SHE)] that is more negative than that of iron (Fe/Fe 2 þ -0.44V/SHE). For this reason zinc is used for sacrificial cathodic protection of steel against corrosion.According to Fischer [1], in metal electrodeposition, zinc can be considered as an intermediate metal, giving rise to medium values of overpotentials due to secondary inhibition resulting from adsorbed hydrolized species.In acid sulfate solutions without an organic additive, BR metallographic cross-sectional structures are obtained (BR: basis reproduction; coherent deposits with coarse crystals whose diameter increases with the deposit thickness; see Fig. 10.1). In chloride electrolytes, even coarser grains are observed, because of the more activating character of chloride ions against sulfate ions [2] and despite the complex formation in solution [3, p. 464]. In cyanide baths, on the other hand, much finer grains are obtained, and the deposits pertain to the FT (field-oriented texture: coherent deposits, with elongated crystals perpendicular to the substrate, with almost constant diameter throughout the deposit thickness) or UD types (UD: unoriented dispersion type; coherent deposit, with small crystals showing three-dimensional nucleation to occur all the time during electrodeposition). Figure 10.2 shows a deposit obtained in a cyanide solution without an organic additive: the structure is initially FT, but it becomes progressively bad. Going from a cyanide bath to a noncyanide alkaline bath should result in still worse deposits because electrolyte complexation decreases [3] and exchange current density increases [4, pp. 528-543].Accordingly, when rather thick deposits are needed and/or if a bright surface is required, organic additives are always present at high concentration (1 g L À1 or more). This always occurs in barrel-and-rack plating of small pieces of equipment, because the local current densities will vary over a wide range. For continuous plating on steel sheets or wires, constant current density and rather good hydrodynamic control may be achieved over the whole cathodic surface, and organic additives are not so much in use.Whatever the pH, zinc is always more negative than hydrogen [5]. In electrolytes where zinc is complexed, its standard reversible potential is still more negative; for instance, for cyanide baths, the reversible potential for reactionin alkaline solution is À1.26 V/SHE [6]. Consequently hydrogen evolution occurs at the cathode as a competitor to zinc deposition, resulting in a decrease of current efficiency and eventually in some atomic hydrogen diffusion into the substrate.Finally, in industrial processes electrolytic plating is an alternative to hot-dip galvanizing. Both processes have advantages and disadvantages. Continual technological improvements make it difficult to conclude in favor of one process over the other. However, hot dip always includes some surface alloying by diffusion, and the deposit thickness is less easily controlled th...

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Chloride hydrometallurgy

Cited by 142 publications

References 42 publications

Lixiviación oxidante de sulfuros complejos en soluciones de cloruro amónico: cinética de la lixiviación de la esfalerita

Lixiviación oxidante de sulfuros complejos en soluciones de cloruro amónico: cinética de la lixiviación de la esfalerita

Complex sulphide-barite ore leaching in ferric chloride solution

Electrodeposition of Zinc and Zinc Alloys

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