Navegando por Autor "Pereira, Paulo Elias Carneiro"

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    Estimativa de recursos minerais e otimização de cava aplicados a um estudo de caso de uma mina de calcário
    (Universidade Federal de Goiás, 2017-03-08) Pereira, Paulo Elias Carneiro; Ribeiro, Carlos Cordeiro; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4765922P6; Rabelo, Marcos Napoleão; http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4702141E9; Ribeiro , Carlos Cordeiro; Borges, . Romes Antônio; Guimarães, Ednaldo Carvalho
    A mining enterprise is composed of a set of successive and interdependent phases between them, which may or may not culminate in the exploitation of the mineral assets. The project begins with a Mineral Exploration phase, whose objective is to discover and subsequently evaluate the deposit for the feasibility of its extraction. This process involves setting the shape, dimensions and grades, resulting in a model that will be used to determine the recoverable reserves, that is, the economically usable part of the mineral resource, which will base the decision on the implementation or not of the enterprise, based mainly on technicaleconomic criteria. The elaboration of the physical form of the geological bodies that control the mineralization (geological model) and the estimation of the geological variables that characterize the quality of the different materials can be done by two approaches: by traditional or by geostatistical methods. The latter approach is currently being preferred, as it is a more accurate alternative and therefore, more reliable over traditional methods. The work uses indicator kriging (IK) and ordinary kriging (OK), both geostatistical tools, for the determination of the geological model and estimation of the geological variables (grades), respectively, of a limestone deposit located at Indiara city, Goiás State. Finally, from the obtained model the optimal limits of the extraction were established, based on the algorithm of Lerchs-Grossmann, that maximize the net present value of the enterprise. The results showed a significant deviation between themodel calculated by IK and the reality (samples), which can have as consequence the present spatial configuration of the sample data. The estimated geological variables also showed important deviations (overestimation and/or underestimation), particularly MgO oxide. The areas of occurrence of such deviations were coincident for all variables, which makes evident the existence of problems with the current sampling grid (spacing between samples and presence of very different sample supports), in such a way that it is recommended to collect additional samples, particularly with standardized supports. The optimal pit delimited a total reserve of 109,436,160.43 tons, with a total strip ratio of 0.13, which makes the venture, at first, attractive. This configuration, however, tends to be modified according to the collection of new geological evidence.