DEMIN - Departamento de Engenharia de Minas

URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/510

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2015 - 201922020 - 20211

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Assunto: search.filters.subject.Speleology

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Agora exibindo 1 - 3 de 3
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    Aplicação do sistema de monitoramento de dinâmica de rocha (SMDR) para controle geotécnico contínuo de cavidade natural subterrânea no Quadrilátero Ferrífero (MG).
    (2021) Fernandes, Adam Barros; Lima, Hernani Mota de; Valentim, Raul Fontes; Gontijo, Alexandre Assunção; Fonseca, Leandro Roque da; Cardoso, Fernando Santos Seabra; Boulhosa, Gabrieli Santos
    Nos últimos anos uma série de estudos tem sido conduzida sobre cavidades naturais subterrâneas em formações ferríferas. Esses estudos decorrem da necessidade de se preservar as cavidades naturais e, ao mesmo tempo, viabilizar de forma sustentável, a operação de uma mina de minério de ferro. Isso ocorre pelo fato da legislação ambiental do Brasil estipular, empiricamente, um raio de proteção de 250 m, de forma a evitar dano ambiental irreversível às cavernas, que por sua vez, bloqueia a lavra de considerável fração de minério de ferro. Dessa forma, com o intuito de verificar a influência do desmonte com uso de explosivos na estabilidade física da cavidade BRU_0034, nas proximidades da Mina de Brucutu da empresa Vale S.A., foram propostos, por intermédio desse estudo, monitoramentos sismográficos e de deslocamento através do uso do Sistema de Monitoramento de Dinâmica de Rocha (SMDR). No que se refere aos resultados obtidos com o SMDR, foi possível verificar por meio dos dados sismográficos e de deslocamento que não houve uma grande movimentação aparente nos sensores durante o monitoramento de desmontes de rochas por explosivos realizados em distâncias inferiores a 250 m.
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    Instrumented geotechnical monitoring of a natural cave in a near mine operation – towards a sustainable approach to mining and preservation of speleological heritage.
    (2019) Brandi, Iuri Viana; Barbosa, Marcelo Roberto; Paula, Rafael Guimarães de; Araújo, Ramon Nunes; Moura, Rafael Simões Vieira de; Lima, Hernani Mota de
    The iron ore mining in Brazil is currently restricted due to federal laws for natural caves protection. Four classes of cave relevance are formally designated based primarily on geological and biospeleological criteria. According to the law, Maximum Relevance caves must be protected, together with a 250 m buffer zone. This protection zone, on the other hand, blocks substantial iron ore reserves that impacts mining projects feasibility and postpones or discontinues several ones. This 250 m buffer zone has a preliminary status and can be increased or reduced according to the results of specific long-term studies that ensure caves’ physical integrity, as well as the maintenance of its ecological balance. Considering the need to preserve the natural caves and to conduct a sustainable mining operation, this paper presents the geotechnical monitoring methodology used to anticipate instabilities in the cave, as well as to optimize the study time, considering an approach through remote instrumentation. A pilot project with operations within the 250 m protected zone of a natural cave was conducted at the iron ore mine N4EN, in Carajas, Brazil. Strain and convergence measurements were conducted on the weaknesses points/zones within the caves, identified during geostructural-geotechnical mapping. The data collected were continuously transmitted via web in real time to a database server; automatically treated and turned into updated reports and control charts available on the Internet from an expert software. The results demonstrated the applicability of remote geotechnical techniques for monitoring the structural stability of caves near mining operations, even when subjected to seismic waves, generated by regular blasting. This approach has contributed to the sustainability of the operations that reached a distance of 75 m from the studied cave that remained stable and with its speleological balance and functionality.
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    Analysis of the economic feasibility of a mining project due to the presence of natural underground cavities.
    (2015) Aquino, Iure Borges de Moura; Lima, Hernani Mota de
    The legislation for the protection and conservation of caves is recent in Brazil. In 2008, the Decree 6.640 was enacted and in 2009, the Normative Instruction Nº 2 by the Brazilian Environment Ministry (MMA, Portuguese acronyms) was published. Mining operations cause a significant impact on the caves when they are present in or next to the mineral body. The impacts include the suppression of cavities and impacts on physical and bio-speleological stability of the caves. On the other hand, the actual legislation causes a significant impact on the mineable reserves when cavities are pres¬ent. This article aims to assess the impact of the natural cavities on the feasibility of a mining project, based on the federal legislation, as well as to propose alternatives to combine mining activity with cave protection. For this research, three scenarios of open pit for a hypothetical ore body were considered for the assessments. This paper presents the results achieved for the three and comments on the necessity of researches to conciliate the conservation of the natural underground cavities with the mining activities.