DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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Resultados da Pesquisa
Item Ore-waste and ore type classification using portable XRF : a case study of an iron mine from the Quadrilátero Ferrífero, Brazil.(2020) Urbano, Emílio Evo Magro Corrêa; Costa, João Felipe Coimbra Leite; Graça, Leonardo Martins; Cipriano, Ricardo Augusto ScholzGrade control is a fundamental activity for Short-Term Mine Planning as it validates the ore-waste and ore type classification of mine faces. Geological mapping and quasi-mining sampling provide indispensable information for the Short-Term Mine Planning team to update block models and for grade control of the run-of-mine (ROM). However, laboratory turnaround can take too long and not be timely for operational needs, affecting mining efficiency. To propose a solution for this issue we tested the accuracy of portable X-Ray Fluorescence (XRF) for ore-waste and ore type classification according to iron and phosphorus grade. Thus, iron ore run-of-mine samples from the Quadrilátero Ferrífero were analyzed with the portable XRF as pressed pellets. As a result, the overall accuracy of ore-waste classification was above 92% for different cut-off grades. On the other hand, while ore type classification had a better accuracy without calibration factors for iron, the use of calibration factors significantly improved the accuracy of ore type classification for phosphorus. Therefore, despite the portable XRF presenting good accuracy for ore-waste and ore type classification, further developments are still necessary on automatic information processing systems and sample support validation so that this analytical tool can be used on a large scale by grade control teams. Finally, the combined use of portable XRF and other techniques, such as Hyperspectral Sensing or XRD, can be of great value for mine operations.Item Influence of soil granulometry on average body size in soil ant assemblages : implications for bioindication.(2017) Milanez, Cinthia Borges da Costa; Majer, Jonathan David; Castro, Paulo de Tarso Amorim; Ribeiro, Sérvio PontesSoil granulometric composition can impose constraints on ant species living in ground habitats, being an important factor in defining the habitat templet, which describes how certain animal life histories, including the trait of body size, can be selected. The ant fauna plays a central role in soil formation, and a vast literature describes such influence, but not the converse. Along with termites, worms and other invertebrates, these organisms promote the formation of channels, pores, and aggregates that influence gases and water moving through the soil profile. On the other hand, it is important to understand whether soil traits constrain insect colonization, so we here ask how soil traits can influence niche specificities, which seems to be a neglected ecological issue. A literature search using the key words ‘ants or Formicidae’ and ‘soil structure or pedogenesis’ revealed numerous references dealing with the influence of ants on soil, but not conversely. We here present a novel geomorphologic approach to habitat templets for two distinct riparian Neotropical ecosystems, based on the amalgamation of soil/sediment analysis with ecological processes and ant species biology. We found that predominance of fine grains favoured the preponderance of small ant species at a threshold of <5 mm in body length. Based on this, we propose the use of a quantitative, theoretically sound, statistical approach to bioindication.Item Assessing the impacts of mining activities on zooplankton functional diversity.(2016) Moreira, Francisco Wagner Araujo; Leite, Mariangela Garcia Praça; Fujaco, Maria Augusta Gonçalves; Mendonça, Fellipe Pinheiro Chagas; Campos, Larissa Paraguassú; Sant'Anna, Eneida Maria EskinaziMining activities generate countless environmental impacts, including heavy-metal contamination, sorting and increased turbidity. In aquatic ecosystems these impacts can drastically affect the initial links of the food chain, such as zooplankton. Methods: To evaluate how the different mining activities can influence the structure and functional diversity of zooplankton, we investigated the geochemical characteristics of the water and sediment in two small impoundments impacted by different mining activities (kaolin and iron extraction). We also explored zooplankton composition, species diversity and functional diversity (feeding guilds taxa). Results: As expected, the water and the sediment of both of the reservoirs showed high concentrations of trace elements, particularly Al, Ba, Fe, Mg, Mn, Sr and Zn. Zooplankton biomass and diversity were markedly reduced (< 12 μg.DW.L-1 and H’ < 1.5, respectively), and negatively correlated with turbidity and total suspended solids. Small microphages dominated the trophic composition of zooplankton, and an alternation of trophic guilds was not observed, since the dynamics of raptorial organisms was essentially linked to the temporal fluctuation of a single species of rotifer (Polyarthra cf. dolichoptera). Conclusions: In addition to changes in the aquatic habitat and zooplankton composition, the functional niches were also affected by the mining impacts. The use of the functional diversity analysis can emerge as a valuable approach to understand how zooplankton communities respond to drastic environmental changes.Item A Life Cycle Assessment study of iron ore mining.(2015) Ferreira, Hélio; Leite, Mariangela Garcia PraçaThis paper assessed the cradle-to-gate life cycle of an iron ore mining. The study was based on production data from an open pit mine located in the Iron Quadrangle/Brazil. The functional unit was defined as “one tonne of iron ore concentrate produced” and the data used were collected directly from the company's production reports covering the time of one year. The evaluation included the classification and characterization of life cycle impacts, not including normalization and weighting as well as sensitivity analysis of results. The evaluation of impacts used SimaPro-7, Ecoinvent 2.0, Eco indicator'99 and IPCC 2007. The results indicated that the use of grinding media in the processes is the main source of environmental impacts in the iron ore production chain, highlighting its contribution to life cycle impacts on human health and quality of ecosystems. Ore transportation by conveyor belts powered by electricity was more efficient in relation to the generation of impacts on the abiotic resources depletion and on climate changes than ore transportation by diesel trucks because the electricity generation matrix in Brazil has significant participation from hydroelectric plants.