A Comparison Between Predictive Tests Results and Natural Weathering in the Figueira Mine, in Southern Brazils
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A Comparison Between Predictive Tests Results and Natural Weathering in the Figueira Mine, in Southern Brazils Mateus João Mubecane Filipe Manharage1 · Ernani Francisco da Rosa Filho1 Received: 18 March 2020 / Accepted: 11 May 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Many studies on acid mine drainage (AMD) use predictive methods, such as humidity cells (HC), to study this problem, as it is often not possible to predict acid generation from field tests. However, some comparisons of HC testing with reality have proven to be unrealistic. In this study, we compared the results of the HC test with historical data from the Figueira mine, in the State of Paraná (southern Brazil). To carry out the work,we collected a fresh coal tailings sample from the Figueira Mine, and compared monthly measurements of pH and electrical conductivity (EC), and concentrations of Fe, Al, Mn, and Zn, over a 5 year period (from 2013 to 2017) with the predictive test results performed following protocol B of the ASTM D5744-13 (2018) standard. The elements were analyzed by ICP-OES. The pH and EC of the HC test were lower than the field data. The HC test underestimated the concentrations of Fe and Mn, while Al and Zn were overestimated. We believe that the overestimations were due to the aluminosilicate buffering capacity and cation exchange capacity of the soil. Keywords Acid mine drainage · AMD · Coal tailings · Geochemical models
Introduction Acid mine drainage (AMD) is one of the main problems that affect the ecosystem near mines. Many factors affect the chemistry of mine drainage, including the type and abundance of metal-bearing sulfides in ore and wall rock, kinetic rates of ore and wall rock dissolution, permeability of the ore deposit or mine tailings, and the ability of the host rock to buffer acidity (Anawar 2013). Various predictive tests (static and kinetic) have been developed; the most commonly used tests are acid base accounting (ABA) and humidity cells (HC), as it is often not possible to predict acid generation using field tests. Geochemical models of AMD is a widely applicable and useful technique to investigate the geochemical reactions occurring in the AMD and contaminant transport in the groundwater and surface water systems. The models incorporates chemical speciation, precipitation–dissolution reactions, ion exchange, acid–base reactions, and redox reactions (Anawar 2013). Geochemical models are based * Mateus João Mubecane Filipe Manharage [email protected] 1
Hydrogeological Research Laboratory, Department of Geology, Federal University of Paraná, Curitiba, Brazil
on well-constrained laboratory and field observations as well as geological and geochemical assumptions. However, collection of field data can take a long time. In Brazil, AMD studies have focused on the coal regions of the south of the country. Brazilian coal is normally classified as low rank, since it contains a high ash and sulfur content (Fallavena et al. 2013). However, the S content
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