Reseña histórica de la actividad minera y metalúrgica en Chile

El presente artículo mostrará una reseña histórica sobre la evolución de la metalurgia en Chile. Para eso comenzaremos con una exposición del trabajo de metales en la época prehispánica, siguiendo con el trabajo de metales durante la conquista europea, la extracción de salitre y posterior desarrollo de la metalurgia extractiva del cobre mediante la revisión de la historia de la Corporación Nacional del Cobre (CODELCO). Finalmente definiremos los desafíos que deberá enfrentar nuestra área en lo relativo al cuidado del medio ambiente que nos exigen los nuevos tiempos, entre otros. Palabras Clave: Historia del cobre; historia del salitre; Chile

Hardening by transformation and cold working in a hadfield steel cone crusher liner

This paper presents the characterization of a secondary cone crusher concave liner made of Hadfield steel used in Chilean mining after crushing copper minerals during all service life. During use, a cone crusher concave liner suffers indentation (cold working) and abrasion; this combination provides the concave with a layer that constantly renews itself, maintaining a surface highly resistant to abrasive wear. The results presented here were obtained using optical microscopy, microhardness test, measuring abrasion using the dry sand/rubber wheel apparatus, and x-ray diffraction peaks analysis through the classic Williamson–Hall method. After analysis of results, two hardened surfaces have been found—one a product of heat treatment and the other due to deformation during use. This work proposes ways to explain them; the first one uses a thermodynamic model to calculate stacking fault energy, and the second compares the liner with cold-rolled samples.Fil: Allende Seco, Rodrigo. Universidad de Santiago de Chile; ChileFil: Artigas, Alfredo. Universidad de Santiago de Chile; ChileFil: Bruna, Héctor. Universidad de Santiago de Chile; ChileFil: Carvajal, Linton. Universidad de Santiago de Chile; ChileFil: Monsalve, Alberto. Universidad de Santiago de Chile; ChileFil: Sklate Boja, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; Argentin

Effect of Copper and Nickel Content on the Corrosion Mechanisms in Ferritic Matrix Gray Cast Irons under Simulated Marine Environments

This article investigated the influence of copper (Cu) and nickel (Ni) on atmospheric corrosion in gray cast iron under simulated marine conditions. The goal was to compare the effect of Cu and Ni addition in castings with weathering steels. Selected alloys were cast, cut, prepared, and heat-treated for microstructure homogenization. Accelerated corrosion tests were conducted using a salt spray chamber. Corroded samples were analyzed for corrosion thickness and deposits using scanning electron microscopy, X-ray diffraction, and electrochemical techniques. The results indicate that alloying elements significantly affect corrosion processes. In the long-term, Cu had a greater impact on the corrosion mechanisms than Ni. Both Cu and Ni exhibited similar effects on the corrosion mechanisms in gray cast iron and weathering steels. In the initial and final stages, the behavior was comparable to that of weathering steels, but in the intermediate stage, it differed from the literature, suggesting the presence of an additional mechanism between these stages

Accelerated atmospheric corrosion in a cast ASTM A48 gray iron

<p></p><p>ABSTRACT Due to the long times required to investigate atmospheric corrosion resistance of metals, data on the subject is scarce. One of these studies is the one made by Southwell et al., where the effect of corrosion in a cast gray iron during 16 years was studied in various environments. This research shows and discusses the behavior of cast gray iron when subject to an accelerated corrosion test, which involves wetting in a salt spray chamber, washing and drying cycles during 40 days. Furthermore, samples were submerged in sea water, both natural and UV-sterilized. A direct relationship amongst the presence of bacteria and an increase of surface roughness was found when subject to these conditions during 14 days. Results show that the cast gray iron shows a bimodal behavior, like the observations reported by Melchers on low-alloy steels and the research by Southwell.et al. As described by Melchers, this behavior generates an inflection point in the evolution of corrosion influenced by the presence of bacteria on the metal/corrosion-products interphase. This is validated observing evidence of bacterial activity identifying the presence of sulphur on the corrosion products by EDS after the accelerated corrosion tests. As observed, accelerated corrosion testing can simulate in a short period the conditions under which marine atmospheric corrosion takes place on cast gray iron during years, including the evidence of bacterial activity.</p><p></p