En la industria minera, los concentrados de cobre, plomo y zinc son comúnmente castigados de manera comercial por su alto contenido de arsénico. En busca de combatir esta problemática, se caracterizó un mineral proveniente de Fresnillo, Zacatecas, con importantes concentraciones de este metal tóxico a fin de someterlo a un baño alcalino y lograr la separación del arsénico del resto del mineral. El análisis químico realizado a la muestra del mineral mediante la técnica de Espectroscopia de Emisión de Plasma Acoplada por Inducción (ICP) y Fluorescencia de Rayos X (FRX) identificó un alto contenido de Fe (17.94 % w/w) y As (12.95 % w/w), los cuales forman parte del sulfuro complejo identificado como arsenopirita (FeAsS) [96-900-0110]. Además, la presencia de estos elementos fue corroborada mediante las técnicas de DRX, MEB-EDS y MOP. Estas ténicas tambien revelaron la presencia de sulfuros de metales base como ZnS y PbS, así como especies de ganga como SiO2 y algunos elementos minoritarios como: Sb, Ag, Cu, Zn y Pb. La construcción de diagramas de Pourbaix utilizando el sistema Fe-As-S-NaOH-H2O a 25 °C, permitió determinar que las especies AsO4 3- y FeO*OH predominan bajo las condiciones experimentales a las que se llevaron a cabo las pruebas preliminares ([Mineral]= 8 g L-1, [NaOH]= 2 mol L-1, 25 °C, RPM= 800 min-1 y 720 min), logrando la disolución de 47 % del semimetal.
During the last glacial termination, the climate system experienced intense global variations whose causes and impacts are not fully defined, particularly for low latitudes. The northwestern Mexico Sky Islands present a climate‐sensitive ideal setting to record palaeoecological and palaeoclimatic changes due to their physiographic complexity and location in the ecotone between temperate and tropical ecosystems. High‐resolution pollen analysis and a detailed sedimentological study were conducted at the Ciénega Tonibabi tropical thorn scrub site. The 15 540–0 cal a bp nearly continuous record shows that the North Atlantic Ocean did have a cold and humid climatic influence during the glacial stages of the end of the Pleistocene, including a sharp pulse during the Younger Dryas. However, a shift to the Pacific Ocean influence occurred during the Holocene, which led to the development of the El Niño conditions prevailing today. Colder and warmer phases follow one another with higher or lower winter precipitation, including a sharp Bølling–Allerød and development and intensification of the North American monsoon. They are reflected in hydrological changes as well as in the advances, retreats and intermingling of coniferous forests and tropical thorn scrub.
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