Owing to the diverse geological processes of genesis, metals occur in earth’s crust in a variety of minerals that form ore deposits across the globe. These deposits significantly differ in terms of their physical and chemical characteristics, and conditions of hosting. Productivity growth in any given metal industry is therefore governed by not only the advancements in technology, but also this unique variation in its natural input in course of cumulative extraction and depletion. Detailed analysis of the changes in process input intensities and sector productivity corresponding to a representative spectrum of geological transitions in copper ores reveals that the continuous and incremental technological developments had successfully offset the detrimental effects of depletion on sector productivity, often aided by the geological characteristics that changed to the miners’ advantage. However, the transition of ores below a threshold level of purity and then into the next prevalent chemical composition, was found to cause a steep rise in input intensities that would lead to a fall in productivity despite the introduction of a widely acclaimed innovative process of copper extraction. The study shows that the impacts of depletion are neither linear, nor uniform, and not always detrimental to productivity. It shows the usefulness of productivity studies in estimating the impacts depletion that may not proceed in strictly sequential manner in the short and medium term, as well as evaluating the benefits of technological change. Though the study is primarily based on copper industry, the findings hold relevance for other metal industries too.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-09-24T13:22:31Z No. of bitstreams: 1 ANTONO AUGUSTO PEREIRA DE SOUSA - TESE (PPGEP) 2007.pdf: 1426545 bytes, checksum: 83eb8c3bb345a67ce10d7dedea6c4ace (MD5) / Made available in DSpace on 2018-09-24T13:22:31Z (GMT). No. of bitstreams: 1 ANTONO AUGUSTO PEREIRA DE SOUSA - TESE (PPGEP) 2007.pdf: 1426545 bytes, checksum: 83eb8c3bb345a67ce10d7dedea6c4ace (MD5) Previous issue date: 2007-09-14 / O Brasil têm participação significativa no mercado mundial de rochas ornamentais e o Nordeste vem se destacando como uma região de granitos exclusivos e de grande aceitação no mercado externo, especialmente, no fornecimento de blocos. O emprego de argamassa expansiva para desmonte de rochas ornamentais, vem sendo um dos métodos mais procurados pelas indústrias extrativas, por suas inúmeras vantagens, ante os outros métodos para lavra. Entretanto, os aspectos econômicos inibem o incremento do uso de argamassa expansiva no Brasil, devido ao elevado custo, por se tratar de um produto importado. O objetivo deste trabalho é estudar algumas matérias-primas de origem nacional, especialmente, minerais não-metálicos do nordeste brasileiro, visando à obtenção de argamassa expansiva. Para desenvolvimento deste trabalho foram realizados ensaios de caracterização como fluorescência de raios-X (FRX), microscopia eletrônica de varredura (MEV), difração de raios-X (DRX), granulometria a laser e análises térmicas (ATD e ATG) e propriedade tecnológica da pressão de expansão das argamassas comerciais para utilizá-las como padrão, em seguida, foram estudadas composições preliminares de argamassa de diferentes formulações. Durante o estudo foi projetado e executado um equipamento para medição da pressão de expansão das argamassas. Os resultados indicaram que as formulações estudadas apresentaram características e desempenho próximos aos das argamassas comerciais. Os resultados obtidos indicaram a utilização do carbonato como principal matéria-prima para a obtenção do constituinte CaO que é o responsável pela pressão de expansão que provoca o desmonte de rochas ornamentais pelo uso de argamassa expansiva. Finalmente, foi desenvolvida e aplicada in loco num bloco de granito uma argamassa teste com 70% de CaO, 20% de CaCO3,10% de Cimento e 4% de retardador Industrial a base de carboximetilcelulose (CMC), hidratada com 42% de H20 potável, provocando a ruptura num período de 29 horas após a aplicação. / Brazil has significant participation in the ornamental rock world market and the Northeast of Brazil is outstanding as a region with fashionable granite and with great acceptation in the outside market, especially in the blocks supply. The use of expansive mortar to ornamental rock dismount is become one of most important method in the extractive industries, due to their advantages when compared with other methods. However, the economic aspects inhibit the increase in the use of expansive mortar in Brazil, due to elevated costs, once is an imported product. The aim of this work is to study some national raw materials, mainly non-metallic minerals from Brazilian northeast region, to obtain expansive mortar. To development of the research it was done characterization analysis (X-ray fluorescence (XRF), scanning electron microscopy (SEM), X-ray diffraction (XRD), particle size by laser and thermal analysis (DTA and TG)) and technological properties measurement (expansion pressure) for the commercial mortar, to be used as a standard. It was studied some preliminary formulations and from this it was proposed the construction of a laboratory equipment to measure the expansion pressure of the mortars. The results indicate that the formulation show performance and characteristics close to the commercial mortars. The results also indicate the use of calcium carbonate as the main raw material to produce CaO, which is responsible for the expansion pressure and for the dismount of the ornamental rocks by expansive mortar. Finally, it was developed in laboratory and applied “in loco” in a granite block an expansive mortar with 70% of CaO, 20% of CaCO3, 10% of cement and 4% of industrial additive (carboxyl methyl cellulose) with 42% of brackish water and a rupture of the rock occurred with 29 hours after employed.