Evaluation of the danger of a tailings pile belonging to an active mine through its characterization and a dispersion model

Abstract

Mining is one of the principal economic activities in Mexico, which in addition to bringing benefits to the population, causes health and environmental problems. This activity produces a lot of wastes, but the main one is tailings. In Mexico, these wastes are disposed of in the open air, and there is no control over them, so the particles of these wastes are dispersed by wind currents to the surrounding population. In this research, tailings were characterized, finding in them particles smaller than 100 microns; in this way, tailings can enter into the respiratory system and hence can cause diseases. Furthermore, it is important to identify the toxic components. The present work does not have previous research in Mexico, and it shows a qualitative characterization of the tailings from an active mine using different analytical techniques. In addition to the data obtained from the characterization of the tailings, as well as the concentration of the toxic elements found, which were Pb and As, a dispersal model was generated and used to estimate the concentration of particles in the wind generated at the studied area. The air quality model used in this research is AERMOD, where it uses emission factors and available databases provided by Environmental Protection Agency (USEPA); Moreover, the model was coupled with meteorological information from the latest generation WRF model. The modeling results estimated that the dispersion of particles from the tailings dam can contribute up to 10.15 µg/m3 of PM10 to the air quality of the site, which, according to the characterization of the samples obtained, could be dangerous for human health and can be estimated up to a concentration of 0.04 µg/m3 of Pb and 10.90 ng/m3 of As. It is very important to make this kind of research to know the risk which people around this disposal sites are exposed to.

Increasing the Sustainability of the Stabilization/Solidification of Potentially Toxic Elements Contained in Tailings from an Active Mine Using a Modified Lime Mortar

“…To evaluate the stabilization/solidification treatment, twenty different mixes were prepared to create the monoliths under study, using mining tailings samples reported in the study by Gonzalez et al, 2023 [32]. Table 1 summarizes some properties of these samples [32], with the dam as an aggregate, modified lime mortar as a binder, and water. The binder used was a modified lime mortar named C5 lime concentrate supplied by Nanocal S.A, C.V (Mexico City, Mexico).…”

“…As a consequence, the compressive strength of these specimens increased. As tailings have a very reduced particle size [32], there is increased contact of the binder in the specimens with high lime content (1:1), enhancing the chemical processes of C-S-H gel formation at their interface. According to the literature, this results in a strengthening of the bond between the binder and the aggregate, consequently leading to an improvement in strength results [47,48].…”

“…The differences in strength values between the different sampling points of mine tailings 1 to 10 were ascribed to the variation in tailings composition. The mine tailings samples are highly heterogeneous and of different natures [32,49]. While point 1 has the largest percentage of residues with pozzolanic reactivity, point 10 has fewer active components and more inert aggregates and non-reactive sand granules (see Section 2.1).…”

“…However, by improving pozzolanic processes, a modified lime-based mortar can incorporate metals such as lead into the silica matrix as effectively as cement [29][30][31]. In the current work, the rationale is that the composition of the tailings, containing high levels of silicates [32][33][34], might aid in the hydraulic properties of lime mortar, thus resulting in increased compressive strength and weather resistance [8,35,36].…”

“…The current study utilizes mine tailings previously examined by González et al in 2023 [32], with Pb and As as the primary potentially toxic elements. These tailings are incorporated as aggregates in a mixture with a modified lime mortar binder to facilitate the solidification/stabilization treatment process.…”