Wind erosion and factors controlling the surface composition in abandoned tailings

Abstract

: Chile has developed its mining industry for decades, mainly in the north of the country, where arid climates dominate. Many of these tailings have been abandoned to the weather. The evaluation of what happens at the surface of abandoned tailings, depending on the dominant mineralogy and climate, will be critical in assessing potential impacts from wind erosion or reworking of these deposits. Two areas of study with different climates ranging from arid to semi-arid were evaluated by mineralogy, chemistry and particle size. Using statistical analysis, it was possible to establish different types of sediments, which mainly differed in secondary mineralogy, giving rise to three clusters. When observing these clusters in the field, different surfaces can be observed, in terms of their cohesion and wind erodibility potential. The mineralogical analysis of each cluster in both climates show that although the surfaces of the deposits are similar, the particle size, amount of pyrite and other phases vary from one site to another. From the characterization of these sites, it is evident that pyrite alone will not generate acidic solutions that lead to the precipitation of secondary phases. These secondary phases will be linked to the climate (meaning available humidity), particle size and quantity of pyrite present and neutralising phases. Depending on these variables, different potentially erodible surfaces will be generated, which will lead to a greater or lesser cohesion of particles and different metal contents which is, in turn, the reason for these tailings to become a public health issue.