Avaliação das causas, impactos e alternativas relacionados ao rompimento de barragens convencionais na indústria de mineração

Abstract

The current events related to the rupture of mining tailings dams, potentiated by the heavy rainfall in the Brazilian regions where they are located, have made the need to assess the environmental and socioeconomic impacts generated, in addition to studying alternatives for the mining activity in the country. Actions have been taken by the mining company Vale to repair the damage caused by the rupture of the waste retention dam in the city of Brumadinho-MG, a disaster that occurred in January 2019. The Agreement signed by Vale and the Government of Minas Gerais was negotiated in R$ 37.68 billion of reais, earmarked for socio-economic and socio-environmental repair projects. With the search in the foreign market, especially China, for higher quality iron ore, there is a need to extract ores with high iron content and greater depth of exploration, resulting in a greater production of tailings. Mining companies have been looking for alternatives for the disposal of these tailings, in order to reduce the impacts and risks generated by the use of conventional dams. In the present work, through a bibliographic review, the phenomena identified as possible causes for the rupture of dams were resented. Specifically, the phenomena of liquefaction, piping and overtopping, identified as the main causes for the collapse of these structures, were studied. The processes of ore beneficiation and the stacking and use of tailings were also assessed, associated with the current scenario of the mining industry. Due to the need to mitigate the risks associated with current dams, this work also aimed to contribute to the study of risk monitoring and control plans aimed at these works. Through the studies carried out, it was possible to verify the current adherence of the mining industries to low-cost alternatives for the disposal of tailings, and how these are not the best in the long term when evaluated safety and sustainability aspects. It was also observed the lack of studies in the field of chemical engineering that can contribute to the development of the mining sector, either in ore beneficiation stage or in the modeling stages of fluid dynamic aspects of a tailing containment dam, being these aspects suggested for deepening and discussion in future works.