Aplicação de método estático para predição de drenagem ácida de mina: estudo em ocorrência de sulfetos metálicos na Bacia do Camaquã/RS - Brasil

Abstract

Mineral deposits are essential resources for the development of society, although they make a major contribution to environmental impacts that harm the quality of the environment. Mining activities promote piles of tailings from active, inactive and abandoned mines, releasing large concentrations of sulphates and heavy metals into the environment that contaminate soils, surface and groundwater. Metals (Pb, Zn, Cu, etc.) extracted from mining processes are often toxic and their mining can, under certain conditions, release harmful elements that activate, migrate and accumulate in various target media, directly or indirectly affecting indirectly plants, animals and humans. This process occurs from an aqueous solution called Acid Mine Drainage (AMD) that percolates in the waste and sterile mines and has a low pH, facilitating the storage and transport of toxic elements. In order to predict an environmental impact even before mining starts, it is necessary to conduct a prediction study for AMD to see if it can occur and what the consequences will be in affirmative situations. This work uses the application of a static test called the Acid-Base Balance to predict whether rocks originating from an occurrence of metallic sulfides in Caçapava do Sul - RS are potentially forming AMD or not. For the application of the test, chemical-mineralogical characterization of the samples and chemical tests were carried out to obtain the parameters Acid Potential and Neutralization Potential. The Pb-Zn samples resulted in values that fit them as potentially non-DAM forming material. Cu samples resulted in values that characterize them as potentially forming AMD material. Although a complete DAM prediction study requires greater sampling and the application and comparison of more than one static test, together with the application of kinetic tests, a single sample with a potentially DAM-forming character already denotes that part of the material in question will form DAM under specific conditions.