Determinação de propriedades reológicas de rejeito de mineração por meio de reômetro rotacional

• Ano de defesa: 2017
• Autor(a) principal: Dias, Neemias Almeida
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Engenharia Civil; Centro Tecnológico; UFES; Programa de Pós-Graduação em Engenharia Civil
• Palavras-chave em Português: Tailings dams; Iron Ore Tailings; Yield Stress; Viscoelastoplastic Materials; Tensão limite de escoamento; Barragens de rejeitos; Rejeito de Minério de Ferro; Tensão Limite de Escoamento; Materiais viscoelastoplásticos; Minérios de ferro; Barragens e açudes; Elastoplasticidade; Reologia; Engenharia Civil; 624
• Link de acesso: http://repositorio.ufes.br/handle/10/9489

Mining activities in Brazil have started a long time ago, in times dating back to 300 years. Currently Brazil still occupies a prominent position in the sector, being the iron ore the flagship of mining activities with gross production of 391 million tons in 2016. Of this total, about 65% represent the ore actually contained in what is mined. Therefore, the processing of the iron ore results in high volume of tailings that needs to be arranged. Although there are several methods to deposit tailings, such as dry stackings, the dams are still the most used. In order to transport them more easily, the tailings are transported hydraulically and thrown in the reservoirs. The contained water must be appropriately drained to avoid excessive pore pressure in the massif and, consequently, cause instabilities. Knowing the rheological properties of these materials is primordial for the studies of stability, wave and rupture propagation and pumping systems design. The present work was developed by means of experiments in a stress controlled rheometer using the vane geometry. The material studied came from the tailings after the rupture of the Fundão dam in 2015 and was collected at different points to analyze the variation of geotechnical and rheological properties. Different kinds of test were employed: continuous ramps of shear rate and shear stress, creep tests and oscillatory tests. The results indicate that the iron ore tailings present viscoelastoplastic and time-dependence behaviours, besides exponential variation of the yield stress as a function of volumetric concentration.