Desastres com barragens de contenção de rejeitos de mineradoras : grandes impactos ambientais, soluções remotas

Abstract

Failure of tailings containment dams from mining are events of low occurrence, but with serious environmental, social and economic impacts. The objective of this work was to elaborate a global panorama of the occurrence of accidents due to the rupture of ore tailings dams and to associate them with the characteristics of the dams, the scattering and toxicity of the tailings, the generated environmental impact and the damage remediation mechanisms. For this, two strategies were adopted: 1. Investigation into reports produced by different world institutions (Commission on Large Dams and Unites Nations Environmental Program - ICOLD; The Center for Science Public Participation - CSP2; World Information on Energy - WISE). 2. Systematic review of the scientific literature on the subject of accidents in tailings storage dams using the Web of Science, Scopus and Scielo databases, from 1990 to 2021. As a result, 366 accidents were identified, which released 279,114,891 million cubic meters of tailings, impacting an area of 4,868.15 km in length and directly contributing to the death of 3,043 people. Other correlations were established and made it possible to identify that the constructive method of raising and mounting was the most common method in rugged dams, with overtopping being the main cause recorded for these failures. In addition, failures were more common in mines extracting copper, gold, lead, coal, zinc and phosphate. Historically, these ores are not the most commercially exploited, not allowing to relate the increase in accident risk with the increase in exploration of a particular ore. The chronological analysis of accidents and their severity showed that there is an increasing trend in the frequency and severity of failures in the last decades, accidents in small dams before the 2000s were more common, while in the occurrences recorded after 2000 there was an increase in ruptures in large dams. The systematic review revealed that despite the low number of articles published (87) until 2021, there was a continuous increase in quantitative and qualitative metrics on the subject of accidents with ore tailings containment basins. The chronological analysis showed an increase in the number of publications from 2006, with an increase from 2016 onwards, mainly associated with accidents with the Fundão dams (Mariana, in 2015), and the Córrego do Feijão dam (Brumadinho, in 2019). The main trends found in the literature were in the categories of environmental impacts and remediation proposals. Publications in general demonstrate the serious environmental impacts and the toxic effect of waste released on living organisms. In the literature, there are also few proposals for mitigating environmental damage caused by the spread of tailings from dams, only 8 articles. Of these, the main trend was phytoremediation. Despite the low number of publications, the results presented show that the remediation techniques used are promising for the recovery of areas degraded by mining tailings.