The leaching of valuable metals from mineral ores is the basis of several extractive economies around the world, but the strategies employed often need to rely on dangerous compounds such as cyanides. Due to the complex nature of most ores, leaching processes are slow and have a low efficiency in noble metal extraction, which is usually improved by fine-milling the mineral. In this manuscript, we consider this strategy, demonstrating that it may increase the amount of silver leaching, but at the expense of a higher consumption of cyanide, which renders the process inefficient (only 2% of consumed cyanide is employed to complex silver). The increase in the yield of the desired product without the smarter use of dangerous compounds is shown as a paradigm of the need to insert green chemistry principles in industrial processes. We further present the result of two potential strategies for g...

Objetivo: Determinar el grado de eficacia de la desinfección química con el digluconato de clorhexidina al 2%, el hipoclorito de sodio al 5 % y del alkacide sobre los conos de gutapercha que fueron utilizados en la obturación de conductos radiculares y comprobar cuál de estas sustancias, frecuentemente utilizadas en odontología, elimina totalmente los microorganismos de su superficie externa en el menor tiempo posible. Material y métodos: Se recolectaron entre los meses de setiembre y octubre, 36 conos de gutapercha cuyas medidas oscilaron entre 25-50; que fueron divididos en tres grupos de 12 muestras cada uno. El estudio se dividió en tres fases: Primero se realizó la identificación microbiológica de los conos de gutapercha tomados del ambiente de la Clínica Odontológica de la Universidad Andina Néstor Cáceres Velásquez. En la segunda fase, estas muestras fueron expuesta...

Leaching of polymetallic sulfides is often challenging due to the complexity of these systems. The main issues are related to the formation of surface by-products or to the presence of different metals that require a greater consumption of chemicals compared to that needed to extract the target metal during leaching. This latter case is followed in the present work using X-ray photoelectron spectroscopy (XPS) during the leaching of a silver-containing polymetallic (Mn-Fe-Pb) sulfide under three different cyanidation procedures: (1) conventional leaching, (2) ultrasound-assisted leaching, and (3) leaching of a sample pretreated in alkaline media. In all cases, leaching results in the build-up of Pb compounds (oxides/hydroxides) on the surface of the minerals, suggesting a mechanism in which Pb is first leached by hydroxide and cyanide and later is re-adsorbed as an external layer on the m...