Avaliação do potencial de geração de Drenagem Ácida de Rocha de duas amostras de minério de ouro sulfetado

This work is aimed at evaluating the potential of Acid Rock Drainage (ARD) from two Brazilian gold sulfidic ore samples, by means of using three of the most traditional ARD prediction techniques: Standard Acid Base Accounting and Modified Acid Base Accounting, as static methods, and humidity cells, as a kinetic method. Samples were submitted to chemical and mineralogical characterization that indicated the presence of traces of sulfide minerals, such as pyrite, arsenopyrite, pyrrhotite and of carbonates, calcite and dolomite. While the Standard ABA results were inconclusive, the Modified ABA NNP results and NP/AP ratio suggested a tendency of TP01 and WP01 being acid generators, this tendency being slightly more pronounced for WP01. Therefore, the kinetic test was conducted to clarify the results. The results from humidity cells for samples TP01 and WP01 indicated the likely oxidation of sulfides resulting in acid production, followed by neutralization by the alkalinity generated by the carbonates. Based on these results, it can be concluded that, although the WP01 sample presented a slightly higher potential for generating ARD compared to TP01, these samples might be at different stages in the process, indicating that TP01 is likely at a more advanced stage of ARD generation than WP01. The fundamental role of kinetic testing was underscored by the results.