4 resultados para Alcoa Mineração

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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The exceptional advance of information technology and computer application to the mineral sector has allowed the automation of several processes of the mineral value chain. ERP systems (Enterprise Resource Planning) provided the platform for the efficient integration of all support activities of the mineral value chain. Despite all advances gathered with the application of computers, it was not possible to date, to effectively integrate the primary activities of the mineral value chain. The main reason for that are the uncertainties present in the productive process, which are intrinsic to the business, and the difficulty to quantify and qualify the benefits obtained with this integration due to the lack of a clear definition of the key performance indicators (KPIs). This work presents an analysis of the ERP systems application in Brazilian mining, identifies the KPIs of some of the most important Brazilian mining companies, and discusses the importance of mapping and measuring these indicators for the effective. management of the mining business.

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A study of the interference of Zn2+ ions on phenol degradation by Fenton reaction (Fe2+/Fe3(+) + H2O2) is reported. One of the first intermediates formed in the reaction, catechol, can reduce Fe3+ to Fe2+ and, in the presence of H2O2 initiates an efficient catalytic redox cycle. In the initial stages of the reaction, this catechol-mediated cycle becomes the principal route of thermal degradation of phenol and its oxidation products. The Zn2+ ion addition enhances the persistence time of catechol, probably by stabilization of the corresponding semiquinone radical via complexation.

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Trichomycterus anhanga is described from the Amazon basin, northern Brazil. The species is diagnosed by the latero-sensory system which is restricted to LL1 and LL2, the pectoral fin with two branched rays, the absence of pelvic fins and girdle, the reduced jaws and pharyngeal dentition, the presence of six to seven interopercular odontodes, the absence of a lateral series of spots, the presence of a small dark spot on the ventral surface of the mandibular symphysis, the narrow comma-shaped palatine, the absence of procurrent rays anterior to the dorsal and anal fins, the position of insertion of the first dorsal-fin pterygiophore and the presence of a single pair of pleural ribs. Trichomycterus anhanga shares with T. hasemani and T. johnsoni a wide cranial fontanel which occupies most of the skull roof. Miniaturization as well as synapomorphies for the T. hasemani group are discussed.

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Devido às suas propriedades geomorfológicas e físico‐químicas, estuários e as lagunas estão entre os ambientes mais sensíveis à ação humana, e o número de trabalhos que trata deste tema tem aumentado rapidamente. O sistema Cananéia‐Iguape (SE Brasil) consiste em um complexo de canais estuarinos e lagunares, localizados no chamado Lagamar, uma Reserva da Biosfera da UNESCO. Esses canais são bordejados por uma vegetação de mangue exuberante, na qual desenvolvem‐se extensos bancos de ostras e mexilhões e que constitui um criadouro natural para espécies de importância econômica, tais como camarões, manjubas, robalos, pescadas, entre outros. Não obstanbte, sua importância ambiental, o sistema vem sofrendo modificações dramáticas nos últimos 150 anos, em função da abertura, em 1852, de um canal artificial, o Valo Grande, conectando o Rio Ribeira de Iguape ao sistema estuarino‐lagunar, afetando as características físico‐químicas e o processo deposicional. Um fator agravante diz respeito ao fato de que atividades de mineração realizadas pela Plumbum S/A entre 1945 e 1995 no Vale do Ribeira.