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ABSTRACT. Among the potential environmental impacts in mining activities, acid mine drainage (AMD) is a relevant problem caused by reactive minerals, such as sulfides, due to their exposure to the surface conditions. This is the context of contamination of a waste pile (BF-04) at Osamu Utsumi mine, closed in 1995 after years of physical and chemical processing of the uranium ore and currently under decommissioning plan. This study is based on the application of the combined geophysical methods of Electrical Resistivity and Induced Polarization and the analysis of previous geochemical data, aiming the evaluation of zones related to the generation of AMD and groundwater flux into the waste pile BF-04, containing sulfide minerals and uranium. The association of high resistivity and high chargeability zones is related to disseminated sulfide minerals in rock with silica cement. Infiltration of meteoric water through those zones induces the oxidation of sulfides, high sulfur concentration in groundwater followed by a drop in pH values, which results in a higher leaching capacity and solubility of ions and heavy metals. In addition, high chargeability zones (higher than 10 mV/V ) represent portions of generation of AMD, while the low resistivity anomalies (under 70â„¦.m) are related to preferential flow zones of the contaminated groundwater. Keywords: minning, sulfides, uranium, electrical resistivity, chargeability. RESUMO. Dentre os potenciais impactos ambientais em mineraA§A£o, a drenagem Aicida de mina (DAM) A© um problema grande onde ocorrem minerais instAiveis como os sulfetos, outrora isolados em subsuperfA­cie. A‰ neste contexto de contaminaA§A£o do meio fA­sico que estAi inserido uma pilha de rejeitos (BF-04) pertencente A  mina de urA¢nio Osamu Utsumi, cujas atividades de mineraA§A£o, processamento fA­sico e processamento quA­mico foram encerradas em 1995, seguidas pela etapa de descomissionamento atA© os dias atuais. Neste estudo foram aplicados os mA©todos geofA­sicos da Eletrorressitividade e PolarizaA§A£o Induzida combinados com dados geoquA­micos prA©vios, com o intuito de avaliar zonas de geraA§A£o e fluxo de drenagem Aicida de mina na pilha de rejeitos de mineraA§A£o BF-04 com sulfetos e urA¢nio. A combinaA§A£o de zonas de alta resistividade e alta cargabilidade revela sulfetos disseminados em rochas com cimento silicAitico. A infiltraA§A£o de Aiguas meteA³ricas nestes locais induz a oxidaA§A£o de sulfetos, liberaA§A£o de enxofre nas Aiguas subterrA¢neas seguida pela queda no pH, que resulta num efluente com alta capacidade de lixiviaA§A£o e solubilidade de sais e metais. Neste sentido, zonas de alta cargabilidade (acima de 10 m V/V ) representam locais de geraA§A£o de drenagem Aicida de mina, enquanto que zonas de baixa resistividade (abaixo de 70â„¦.m) revelam zonas preferenciais de fluxo do efluente. Palavras-chave: mineraA§A£o, sulfetos, urA¢nio, resistividade, cargabilidade.

INTEGRATION OF GEOPHYSICAL METHODS IN THE STUDY OF ACID DRAINAGE IN URANIUM MINING WASTE