ordem da forma jurídica e as políticas de segurança de barragens de rejeitos minerais

O trabalho examina, por meio de uma abordagem interdisciplinar, problemas que tem surgido com as atividades de mineração e construção de barragens de rejeito no Brasil, com reflexões jurídicas, ambien­tais e políticas. Para isso, aborda as respostas internacionais, desafios da gestão de resíduos e prevenção de acidentes, cotejando-as com a legislação brasileira e com a forma como são classificadas as barragens dentro da Política Nacional de Segurança de Barragens (PNSB). Utilizando de uma revisão bibliográfica robusta e crítica foi possível perceber que o atual modelo adotado no Brasil cria e recria distorções espa­ciais e temporais, afetando os mais diversos territórios. Hoje o Estado permite que as empresas de mine­ração façam o que quiserem, da forma que desejarem, construindo barragens cada vez maiores, sem li­mitadores. Com a expansão das barragens ocorre um desperdício de natureza, elevação dos riscos e vul­nerabilidades nos territórios e também, uma redução da eficiência produtiva, sendo o Estado correspon­sável em casos de desastres/crimes corporativos. Palavras-chave: barragem de rejeitos; interdisciplinaridade; legislação; regulação; fiscalização. Abstract The work examines, through an interdisciplinary approach, problems that have arisen with the activities of mining and construction of tailings dams in Brazil, with legal, environmental and political reflections. To this end, it addresses international responses, challenges of waste management and accident prevention, comatose them with Brazilian legislation and how dams are classified within the National Dam Safety Policy (PNSB). Using a robust and critical literature review, it was possible to perceive that the current model adopted in Brazil creates and recreates spatial and time distortions, affecting the most diverse territories. Today the state allows mining companies to do what they want, as they wish, building ever larger dams without limiters. With the expansion of the dams occurs a waste of nature, increased risks and vulnerabilities in the territories and also a reduction of productive efficiency, being the state coresponsible in cases of disasters / corporate crimes. Keywords: tailings dams; interdisciplinarity; legislation; regulation; surveillance. El orden de la forma legal y las políticas de seguridad de las presas de relaves minerales Resumen La obra examina, a través de un enfoque interdisciplinario, los problemas que han surgido con las activi­dades de minería y construcción de represas de relaves en Brasil, con reflexiones legales, ambientales y políticas. Con este fin, aborda las respuestas internacionales, los desafíos de la gestión de residuos y la prevención de accidentes, en coma con la legislación brasileña y cómo se clasifican las presas dentro de la Política Nacional de Seguridad de presas (PNSB). Mediante una revisión de la literatura sólida y crítica, fue posible percibir que el modelo actual adoptado en Brasil crea y recrea distorsiones espaciales y de tiempo, afectando a los territorios más diversos. Hoy en día el estado permite a las empresas mineras hacer lo que quieran, como deseen, construyendo presas cada vez más grandes sin limitadores. Con la expansión de las presas se produce un desperdicio de naturaleza, mayores riesgos y vulnerabilidades en los territorios y también una reducción de la eficiencia productiva, siendo el núcleo estatal responsable en casos de desastres / delitos corporativos. Palabras clave: presa de relaves; interdisciplinaridad; legislación; reglamento; vigilancia.

A Failure Modes and Effects Analysis Framework for Assessing Geotechnical Risks of Tailings Dam Closure

Tailings dams remain on site following mine closures and must be designed and reclaimed to meet long-term goals, which may include walk-away closure or long-term care and maintenance. The underperformance of these structures can result in significant risks to public and environmental safety, as well as impacts on the future land use and economic activities near the structure. In Alberta, Canada, the expectation is for a tailings dam to be reclaimed and closed so that it can undergo deregistration. To aid in assessing the risks of underperformance during and after closure, a Generalized Failure Modes and Effects Analysis (G-FMEA) framework was developed to assess the long-term geotechnical risks for tailings dams in Alberta, with the goal of assessing the potential success of a tailings dam closure strategy. The G-FMEA is part of an initiative to enhance closure evaluations in Alberta in a collaborative effort between industry, the regulator, and academia. The G-FMEA incorporates the element of time to account for the evolution of the system, which should be applied at the planning stage and updated continually throughout the life of the facility. This paper presents the developed G-FMEA framework for tailings dams in Alberta, including the developed risk matrix framework.

Effects of Geosynthetic Reinforcement on Tailings Accumulation Dams

Owing to the complexity of current reinforcement mechanisms, test results from existing models alone cannot provide a basis for the design of new tailings dam reinforcement projects. On-site reinforced tailings accumulation dam testing is thus required to further understand the reinforcement mechanism. In this study, the influence of reinforcement on tailings dams and the variation law of pore water pressure (PWP) and internal pressure (IP) in the dam body after slurry discharge were analysed, and a comparative analysis was performed. The results showed that during the field test, the PWP and internal earth pressure of the accumulation dam after grouting gradually increased over time. Reinforcement can greatly reduce the PWP and IP of the reinforced dam; compared with geotextiles, the reinforcement effect of geogrids is slightly greater. Based on these results, we conclude that geosynthetics are a good choice for strengthening tailings accumulation dams.

Hydraulic Erosion Rate of Reinforced Tailings: Laboratory Investigation and Prediction Model

Tailings dams are high-potential-energy dams built to store various ore tailings, and the overtopping failure caused by hydraulic erosion is one of the most common failure modes. The characteristics of hydraulic erosion of the reinforced tailings were studied by using the self-made erosion apparatus with four kinds of reinforcement spacing 2.5, 1.7, 1.3, and 1.0 cm, respectively. The test results show a positive correlation between the reinforcement spacing and erosion rate of tailings. Based on the sediment scouring theory, the scouring constant in the erosion rate formula is determined to be 0.056 mm/s; a prediction model for the hydraulic erosion rate of reinforced tailings is established by introducing the collapse coefficient into the results of the overflow test of reinforced tailings. This model can provide a reference for the prediction of overtopping-induced erosion failure of the reinforced tailings dam.

Study on Hydraulic Incipient Motion Model of Reinforced Tailings

Once the flood overtopping accident of a reinforced tailings dam occurs, it will cause great property losses and serious environmental pollution to the downstream residents. In order to further study the microscopic characteristics of the hydraulic erosion of reinforced tailings dams, considering that the beginning of reinforced tailings particles is the basis of flooding and erosion of reinforced tailings dams, in this paper, a reinforced tailings hydraulic erosion facility was used to carry out the tailings particle start-up test with reinforcement spacing of 5.0, 2.5, 1.7, 1.3, and 1.0 cm, and the influence the law of critical incipient velocity of tailings particles with different reinforcement spacing was revealed. The test results show that, the smaller the reinforcement spacing, the larger the incipient velocity of the reinforced tailings sample. Based on the sediment incipient motion theory, it is assumed that the resistance direction of particle incipient motion is opposite to the particle motion direction. A reinforcement coefficient is introduced to establish the incipient velocity formula of reinforced tailings particles. This model can provide theoretical support for the study of the hydraulic erosion rate of a reinforced tailings dam.

Panorama das barragens de rejeito de minério no Quadrilátero Ferrífero (MG) e suas implicações para a segurança hídrica da Região Metropolitana de Belo Horizonte-MG

<p>O presente trabalho objetiva investigar as lacunas legais no tocante à segurança de barragens de rejeito de minério nas bacias de contribuição dos mananciais que abastecem a Região Metropolitana de Belo Horizonte (RMBH), evidenciando suas implicações para a manutenção da quantidade e da qualidade das águas. Por conseguinte, é elaborado um panorama das barragens da bacia do Alto Rio das Velhas em termos espaciais e legais, principalmente quanto à conformidade em relação à Política Nacional de Segurança de Barragens (PNSB). Os resultados obtidos mostram uma série de lacunas nos aspectos legais das estruturas, sobretudo no tocante à estabilidade dos barramentos, cenário que, por sua vez, compromete a segurança hídrica dos mananciais e o abastecimento de água da RMBH.</p><p><span>Abstract</span></p><p>SCENERY OF ORE TAILINGS DAMS IN THE QUADRILÁTERO FERRÍFERO “IRON QUADRANGLE” (MG) AND IMPLICATIONS FOR WATER SECURITY IN THE METROPOLITAN REGION OF BELO HORIZONTE, MINAS GERAIS STATE, BRAZIL</p><p>This paper aims to investigate the legal gaps regarding the safety of ore tailings dams in the contribution basins of the water sources that supply the Metropolitan Region of Belo Horizonte, highlighting their implications for maintaining the quantity and quality of water. In this context is featured an overview of the spatial distribution and legal aspects of the dams in the Upper Velhas River basin, involving their compliance with the National Dam Safety Politics (PNSB). The results show many legal gaps, especially regarding the structural stability, which, in turn, compromises the water resources security and the regional water supply processes.</p>