Estimativa de recursos minerais e otimização de cava aplicados a um estudo de caso de uma mina de calcário
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2017-03-08
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Universidade Federal de Goiás
Resumo
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.
Descrição
Palavras-chave
calcário, Cava ótima, Geoestatística, Krigagem, Modelagem geológica, Geological modelling, Geostatistic, Kriging, Limestone, Optimal pit
Citação
PEREIRA, P. E. C. Estimativa de recursos minerais e otimização de cava aplicados a um estudo de caso de uma mina de calcário. 2017. 171 f. Dissertação (Mestrado em Modelagem e Otimização) - Universidade Federal de Goiás, Catalão, 2017.