Avaliação da disposição de rejeitos de minério de ferro nas consistências polpa e torta

• Ano de defesa: 2013
• Autor(a) principal: Andréa Mírian Costa Portes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Rejeito filtrado; Métodos de disposição; Riscos associados; Minério de ferro; Engenharia de transportes; Refugos (Metalurgia); Mecânica do solo; Residuos
• Link de acesso: http://hdl.handle.net/1843/BUOS-9CPHGY

Among the various tailings disposal methods, Brazilian mining companies generally opt for disposal at the surface in the form of slurry held behind earthen dams. However, besides slurry, tailings can be processed to take on other physical states, such as thickening into paste or cake form, implying specific geotechnical behaviors. The thickening process, involving filtering to remove the water, is a feasible alternative that can mitigate many of the risks of conventional disposal of tailings in slurry form behind dams, due to their improper construction and/or maintenance and the inherent environmental risks, especially in the event of rupture. Despite the internationally recognized environmental advantages of the filtering/dewatering practice, it is not typically used by Brazilian miners. Therefore, this article presents the results of a conceptual analysis of the environmental performance and safety of filtering iron ore tailings to produce cake in comparison with conventional disposal in slurry form. The method basically consists of preparing alternative scenarios for disposal of tailings, deterministic and probabilistic stability analyses, as well as risk assessment through FMEA, for the purpose of identifying the failure modes and their consequences in each scenario. The three scenarios analyzed were disposal in piles of filtered tailings, in tailings ponds held by compacted earth dams and by dams made of cycloned tailings. During the work it was possible to contemplate aspects of the state of the practice for disposal in piles of compacted filter cake. The results indicate that this disposal method has the least environmental impact, since the structure is easily recovered. The deterministic and probabilistic stability analyses attest to the good geometry of these piles and indicate, for the assumed parameters, lower risks compared to the two dam scenarios. The risk assessments through FMEA were important do reveal the possible failure modes and their consequences for each scenario studied. Among the three, the filtered tailings pile presents the lowest risk of failures.