ASPECTS OF THE DRAINAGE OF TAILINGS DAMS WITH UPSTREAM LIGHTING: THE CASE OF DAM I, OF THE CÓRREGO DO FEIJÃO MINE, IN BRUMADINHO – MG

Abstract

In Brazil, serious accidents involving tailings dams have been frequent. This work seeks to show aspects of these dams related to the drainage system that can compromise safety, especially in tailings dams built with upstream raising lifts. The method adopted consists of bibliographical research and presentation of some drainage techniques and devices and their relationship with percolation, loading and development of pore pressures that may affect the safety of the dam. Construction techniques are also presented and, finally, a case study involving the accident, which occurred in January 2019, at the Córrego do Feijão mine dam in the municipality of Brumadinho in the State of Minas Gerais is presented. Despite the fact that the accident does not yet have a formal technical and legal definition of which factors may have contributed to the collapse, it is undoubtedly possible to assume that an important cause may be related to the development of pore pressures in the massif. The issue related to external causes is not being addressed in this work, although overloads and vibrations can also contribute to a loss of bus stability. Finally, some considerations indicated in technical reports are presented that point out some hypotheses about the dynamics of the accident and a possible link with the presence of water in the massif composed of iron mining residues, contained by an upstream elevated dam and closed in 2016 after the tenth upgrade.