ResumoA Mina Lagoa das Flores constitui uma das principais ocorrências de minério de ferro situada no Complexo Serra Azul, localizado na borda noroeste do Quadrilátero Ferrífero, onde se encontram outras empresas como Arcelor Mittal, Usiminas, MBL e MMX. Atualmente, são gerados cerca de 2,2 Mt/ano de estéril, sendo 70% constituído de itabirito compacto cujo recurso mineral é da ordem de 370 Mt. Os objetivos são, para esta tipologia, a caracterização mineralógica e o desenvolvimento de rotas de processo, por ensaios de bancada com estudos de work índex, índice de abrasão e ensaios de concentração magnética, deslamagem e flotação. O minério mostrou-se composto essencialmente por quartzo e hematita martítica, com magnetita minoritária; o teor médio de ferro foi 34,3%; o grau de liberação do quartzo foi de 92% abaixo de 0,075 mm. A melhor opção para aproveitamento do minério é a moagem a -0,15 mm, seguida de concentração magnética de médio e alto campo, remoagem a -0,053 mm e flotação catiônica reversa. Assim, é possível obter um concentrado final com 67,8% Fe e 1,84% SiO 2 e recuperação metálica de 83%. Palavras-chave: Itabirito; Caracterização mineralógica; Rota de processo; Resíduos. STUDIES OF CHARACTERIZATION AND CONCENTRATION OF COMPACT ITABIRITE OF THE SERRA AZUL COMPLEX, MG AbstractThe Lagoa das Flores Mine is an important iron ore deposit located at the Serra Azul complex in the Northwestern border of the Ferriferous Quadrangle, Minas Gerais, where other important mines also occur, such as Arcelor Mittal, Usiminas, MBL and MMX. Presently 2.2 Mt/year of waste are generated; 70% of this waste is comprised by compact itabirite whose mineral resource is of the order of 370 Mt. The goals are to perform a mineralogical characterization and the development of process routes for this ore type by bench scale testing. The latter was carried out by work index and abrasion index determinations and magnetic concentration, desliming and flotation testing. The ore was composed by quartz, martitic hematite and minor magnetite; the average iron content was 34.3% and the quartz liberation degree was 92% below 0.075 mm. The best processing route are grinding to -0.15 mm, followed by medium and high strength field magnetic concentration, regrinding to -0.053 mm and reverse cationic flotation. Therefore, a final concentrate with 67.8% Fe, 1.84% SiO 2 contents and metallic recovery of 83% is obtained.

The power transformer is one of the most important equipment in an electric power system. If this equipment is out of order for some reason, the damage for both society and electric utilities are very significant. In this work, we present a comparative study of the application of Multi-Layer Perceptrons trained via Rprop algorithm and Decision Trees in the classification of incipient faults in power transformers. The proposed procedures have been applied to real databases derived from chromatographic tests of power transformers. The results obtained by both techniques are compared and fully described. The classifiers discussed here can be seen as a very important component in power transformer predictive maintenance activities.

This work is concerned with the efficient allocation of trucks to shovels in operation at open-pit mines. As this problem involves high-value assets, namely mining trucks and shovels, any improvement obtained in terms of operational efficiency can result in considerable financial savings. Thus, this work presents multi-objective strategies for solving the problem of dynamically allocating a heterogeneous fleet of trucks in an open-pit mining operation, aiming at maximizing production and minimizing costs, subject to a set of operational and physical constraints. Two Multi-objective Genetic Algorithms (MOGAs) were specially developed to address this problem: the first uses specialized crossover and mutation operators, while the second employs Path-Relinking as its main variation engine. Four test instances were constructed based on real open-pit mining scenarios, and used to validate the proposed methods. The two MOGAs were compared to each other and against a Greedy Heuristic (GH), suggesting of of the MOGAs as a potential strategy for solving the multi-objective truck dispatch problem for open-pit mining operations.

O presente trabalho teve como objetivo a elaboração do diagnóstico do uso da energia elétrica no setor extrativo de rochas ornamentais capixaba, utilizando-se como ferramenta a análise das informações dos Relatórios Anuais de Lavra apresentados à Agência Nacional de Mineração, bem como a aplicação de questionários direcionados às empresas do setor extrativo do Espírito Santo. As informações obtidas através dos Relatórios Anuais de Lavra propiciaram o entendimento das principais fontes de energia elétrica e do indicador de intensidade energética referente à produção das rochas ornamentais. Por sua vez, as análises dos dados apresentados como resposta aos questionários oportunizaram o entendimento de uma forma mais depurada das principais fontes de energia elétrica, bem como a percepção das empresas no tocante à gestão da energia elétrica, ações de eficiência energética e conhecimento da norma ISO 50.001. Por fim, verificou-se que o setor extrativo mineral se apresenta com uma grande oportunidade na temática de gestão e eficiência energética.

This article presents a guide to be followed by mining companies willing to open a dimension stone quarry in Brazilian territory. It highlights the main technical documents required by Federal legislation to obtain mining authorization. These documents and their singularities were compiled based on a study of Brazilian mining laws, other normative instruments and scientific literature. The Brazilian mining law describes five Federal authorizations, in which two could be obtained for the dimension stone mining purpose: authorization/concession and licensing regimes. To obtainment the main mining permission may extend for many years. However, it is possible to acquire a kind of provisional permission in much less time, so that the quarry activities can begin before the acquisition of the main permission, which has no deadline. In general, the required technical mining dossier shows a wide range of information. For these reasons, one of the best ways to reduce the time spent through legal procedures is based upon paying special attention at the quality and level of proper instruction of the documents delivered to National Mining Agency (ANM). The author's experience reveals that knowledge of the technical documents provides legal safety for the company, in a context where the miner has to deal with economic, regulatory, environmental and occupational risks.