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Entre los agentes quelantes destacan los ácidos hidroxámicos, los cuales han mostrado un rendimiento superior sin las preocupaciones de salud, seguridad y medio ambiente asociadas con los xantatos. En este estudio se evaluó y comparó mediante espectroscopia infrarroja y mediciones de potencial zeta, la adsorción química de dos hidroxamatos, sobre la superficie de la anglesita. Asimismo, se efectuaron mediciones de microflotación para evaluar y comparar su respuesta a la flotación. Finalmente, se propusieron los mecanismos de interacción entre la anglesita con los aniones hidroxamato en solución acuosa, los cuales presentan reacciones globales y ayudan a entender la manera en que reaccionan ambos colectores. En general, las pruebas de microflotación mostraron mayores recuperaciones de anglesita usando AOH. Se sugiere que los aniones benzohidroxamato y octanohidroxamato se adsorben químicamente sobre la anglesita en la mayoría de las condiciones estudiadas, excepto sobre la anglesita acondicionda a pH 5, en donde se encuentran fisisorbidos.

Los minerales de telururo de oro son refractarios a la cianuración convencional, por lo que para su procesamiento requieren de un tratamiento previo, o el uso de agentes lixiviantes alternos al cianuro. La creciente presencia de los telururos de oro, ha creado la necesidad de buscar nuevas alternativas para el tratamiento de este tipo de minerales. En este trabajo se propone un proceso de extracción empleando ácido de Caro como pre oxidante del mineral para una posterior cianuración convencional. Para esto, se utilizó un mineral de telururo de oro, ya cianurado con anterioridad, con presencia de calaverita (AuTe2). Se encontró que el ácido de Caro es un efectivo agente lixiviante, produciendo una disolución ácida directa y permitiendo la obtención de valores de oro que se consideraban no recuperables.

This work demonstrates that, by adjusting the surface electrical charge of flocs, it is possible to optimize the arsenic adsorption during electrocoagulation with zinc anodes, and since there are still ‎limited works focused on studying this subject, this study is innovative. To make this study possible, the arsenic adsorption process was isolated. The pH and electrical conductivity of the electrolyte were observed to have very important effects on the control of the surface charge of the zinc hydroxide flocs (zeta potential). It was found that the optimal operating conditions of pH 7.0 and 1.19 mS/cm were able to reach a higher arsenic adsorption capacity (165.5 mg/g) than other flocs generated with aluminum or iron anodes. It was noted that the flocs are formed mainly by zinc hydroxides (β–Zn(OH)2 and e–Zn(OH)2), but adamite (Zn2AsO4OH) can be formed as the arsenic is adsorbed. The arsenic removal percentages were 96.15%, 84.35%, and 71.73% when the initial concentrations of this element were 10, 20, and 30 mg/L, respectively (t = 15 min, T = 25 °C, and 0.04 g/L of flocs). The isotherm analysis shows that the chemical adsorption follows second–order kinetics, depending on the floc and arsenic concentrations.

In cyanidation process, the free cyanide concentration is the main variable that controls the efficiency of the process, and the plant operators determine it by silver nitrate titration. If sulfide ion is present in the solution the free cyanide concentration cannot be determined by titration as the silver added in the titration reacts with the sulfide ion to form a black solid (silver sulfide) that hinders the visual detection of the titration endpoint. This work proposes the potentiometric detection of the endpoint of the titration and demonstrates, thermodynamically and with analyses performed in synthetic solutions, that it is possible to determine both, sulfide and cyanide in the solution, even if the endpoint of the titration cannot be visually detected.

In present article, influence of grain refinement (Al5Ti1B) on the morphology of iron-rich β-phase intermetallic compounds in Al-12Si-Cu-Mg alloy having two addition levels of iron as alloying element has been reported. The mechanical properties such as tensile strength and ductility of base alloy and the grain refined alloys were measured. The effect of grain refiner on quality index of the alloys on the basis of mechanical properties was also assessed. It was observed that the higher iron content in an alloy results in coarser iron-rich β-phase intermetallic compounds in more quantity than low iron content alloy. The addition of grain refiner in an alloy modifies the distribution of iron-rich intermetallic compounds and changes their morphology from needle to blocky and Chinese script form besides reducing their average length and aspect ratio, which in turn improves the mechanical properties significantly. Further, it was observed that alloy with high iron (2.68 wt%) content required more quantity of g...