EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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11 resultados
Resultados da Pesquisa
Item Blending Linz–Donawitz and Blast Furnace slags with the Kambara reactor byproduct to improve their reuse in roadworks.(2022) Schumacher, Aécio Guilherme; Gomes, Guilherme José Cunha; Schneider, Denise S. G.; Pires, Patrício José Moreira; Gomes, Ruan Gonçalves de SouzaThe use of industrial byproducts as replacement of natural aggregates has been extensively investigated to design eco-friendly roads. One of the most examined byproducts for this purpose is steel slag. However, existing studies do not explore the blending of different slags to enhance the engineering performance of base layers. The applicability of Linz–Donawitz (LD), Blast Furnace (BF) and Kambara Reactor (KR) steel byproducts is evaluated as a single base layer for rural (unsurfaced) roads in Brazil. A series of laboratory experiments were performed to assess the characteristics of eight soil-byproduct mixtures with 50% and 75% byproduct contents, including new blends of LD/KR and BF/KR slags. Additionally, the most suitable mixture was proposed considering different performance indicators. Results demonstrate the coarse-grained, nonplastic and non-expansive nature of the byproducts, with CBR values higher than 100%. The more byproduct added to soil, the larger is the strength and the lower the expansion. The mixture with 75% of the proposed LD/KR blend and 25% of a clayey soil was considered as optimum, based on a trade-off between engineering properties, environmental impacts, and material costs. Findings and discussions are relevant to reduce waste stockpiles of steel companies, helping engineers and policy makers reuse blended slag byproducts.Item Alkali-activated materials produced using high-calcium, high-carbon biomass ash.(2022) Silva, Thiago Henrique; Lara, Luis Felipe dos Santos; Silva, Guilherme Jorge Brigolini; Provis, John Lloyd; Bezerra, Augusto Cesar da SilvaEucalyptus ash (EA) was used in this study as a high calcium ash (HCA) precursor for alkali-activated binders. The EA used also has high carbon unburned (High loss on ignition). This type of ash is one of the waste products from biomass-fuelled thermoelectric plants, and annually thousands of tons are discarded as a by-product of the energy generation process in Brasil, but it is rich in unburnt carbon which means that it is challenging to use in cementitious systems. Eucalyptus is a biomass that removes CO2 from the atmosphere by photosynthesis and part of this carbon content remains in the ashes, generating CO2 capture when EA is incorporated in the production of alkali-activated binders. The objective of the present study was to evaluate the properties of the material obtained by the alkali-activation of the high-calcium high-carbon biomass ash to generate a cementitious binder, with different pastes proportions of EA and silica fume (SF), activated by sodium hydroxide. With the different pastes, mortars were produced using standardized sand. The results obtained from the pastes and mortars were satisfactory in several aspects. The mechanical results of the alkali-activated mortars were comparable those of Portland cement mortars. Mortars degraded methylene blue more efficiently in illuminated conditions, even after high adsorption for 24 h in the dark. The content of leached ions in the remaining solutions met potability standards.Item Estudo de viabilidade técnica e econômica para aplicação de organic photovoltaics (OPV) em um edifício residencial.(2020) Souza, Bruna Araújo; Medeiros, Jackson Cristiano de; Xavier, Marcus Vinícius Souza; Miranda, Sérgio Alves de; Fernandes, Walliston dos Santos; Santos, José Ronaldo Tavares; Vida, Laísa Emmanuelle Brandão Miguel; Dias, Helciene Moreira; Santos, Fábio TavaresO OPV (Organic Photovoltaics) é recomendado para locais onde não se possa instalar placas solares, como claraboias de shoppings ou fachadas de prédios. Este produto é desenvolvido e comercializado no Brasil e no mundo pela startup mineira (SUNEW), que vem se destacando como uma excelente alternativa de geração de energia elétrica. Quanto à metodologia, este estudo pode ser classificado como qualitativo, quantitativo e descritivo e para tal foi utilizado como referência um edifício residencial de médio porte. Ademais, foram analisados a utilização atual do local e paralelo a coleta de dados, quantificou-se o investimento inicial e o ganho ambiental por redução na emissão de carbono. Conclui-se que, os resultados obtidos foram satisfatórios por ser um produto novo no mercado. Entretanto, sua implantação requer um investimento elevado, o que inviabiliza sua aplicação em pequenos projetos, sendo direcionado a um público que visa produtos sustentáveis, e empresas que se apoiam no marketing verde para atingir esse nicho específico.Item Conventional hammering of a Fe-7.2%Ni alloy sample from Itutinga meteorite : an evaluation of its formability and functionality.(2020) Nunes, Gilson Antônio; Silva, Gilberto Henrique Tavares Álvares da; Costa, Adilson Rodrigues daUsing a mechanical forming process used in the beginning of metallurgy, the samples from the iron meteorite Itutinga were heated and plastically deformed by hammering. Two sharp pieces, similar to small arrowheads, were produced and characterized microstructurally by optical microscopy and scanning electron microscopy (SEM/EDS/EBSD), complemented with Vickers hardness. As expected, the observations pointed to the presence of α2 phase, cracks, oxidation and deformed taenite lamellae. To assess the performance of the arrowheads a penetration test was done on a leather sample. The results demonstrated the possibility of making a useful rudimentary arrowhead from of iron meteorite.Item Hydraulic tiles produced with fine aggregates and pigments reclaimed from iron ore tailings.(2021) Fontes, Wanna Carvalho; Carvalho, José Maria Franco de; Silva, Keoma Defáveri do Carmo e; Silva, Guilherme Jorge Brigolini; Segadães, Ana Maria Bastos Costa; Peixoto, Ricardo André FiorottiConfronted with the growing ecological awareness of the consumer market, the construction industry has been seeking strategies to promote a higher insertion of waste in the production chain while contributing to the technological improvement of processes and products, as well as mitigation of social and environmental impacts and, at the same time, conferring intangible value to the product. In this sense, the present work describes how iron ore tailings (IOT) can be used in the production of cement-based (hydraulic) tiles. The physical, chemical, and mineralogical characterizations carried out demonstrated that the IOT benefciation (segregation) process resulted in a high-quality siliceous aggregate and a Fe-rich clay. The latter can be used as a pigment, whose pigmentation and cementing potentials improve with calcination and grinding. Compared to hydraulic tiles prepared with conventional materials, those obtained with the IOT-based materials displayed a pleasing appearance and the expected physical–mechanical performance.Item Iron ore tailings as a supplementary cementitious material in the production of pigmented cements.(2020) Magalhães, Luciano Fernandes de; França, Sâmara; Oliveira, Michelly dos Santos; Peixoto, Ricardo André Fiorotti; Bessa, Sofia Araújo Lima; Bezerra, Augusto Cesar da SilvaIn this paper, the characterisation of iron ore tailings (IOT) was carried out to examine its use as a supplementary cementitious material (SCM) to produce coloured composite cements. The IOT was heat treated, and ten different mixtures were prepared, substituting Portland cement for 10, 20 and 30 wt%. The IOT presented the sum of oxides of silicon, aluminium and iron higher than the minimum prescribed in Brazilian and international standards to be considered a pozzolanic material. The grain size of the IOT was smaller than the grain size of the Portland reference cement and met the standards used. The electrical conductivity indicated that all IOTs are pozzolans, and the index of pozzolanic activity indicated that the heat treatment at 750 C transformed the IOT into pozzolan. The heat treatment changed the colour of the IOT, and that influenced the colour of the composite cement with IOT and in turn, the colour of the produced mortars. In the IOT without thermal treatment, the presence of the kaolinite mineral was identified, and the thermal treatment led to the non-identification of this mineral, probably transforming it into an amorphous phase. The thermogravimetric analysis confirmed the transformation of kaolinite into metakaolinite. The compressive strength presented by IOT composite cement was adequate for several commercial cements provided for in Brazilian and in international standards. Cement with IOT showed lower values de loss of mass and microstructure with less damage under acid attack, and this behaviour was optimized with increases in the percentage and temperature of IOT heat treatment. Finally, the synergy between milling and heat treatment optimized the use of IOT as a pozzolan capable of changing the colour of the final cementitious product, as well as its use as an SCM.Item Mining communities from a resilience perspective : managing disturbance and vulnerability in Itabira, Brazil.(2014) Leis, Joseph Wasylycia; Fitzpatrick, Patricia; Fonseca, Alberto de Freitas CastroThis paper applies the resilience lens to a social–ecological system characterized by the presence of large-scale mineral extraction operations. The system in question is the Brazilian community of Itabira, Minas Gerais, host to an iron ore operation of Vale, the world’s second largest mining corporation. Utilizing a resilience assessment framework, this study describes the various components of the Itabira social–ecological system revealing the challenges brought about by mining’s dominance. Data collection included literature reviews and semi-structured interviews with 29 individuals representing different stakeholder groups. Findings revealed that, despite recent efforts by government to regulate the industry, the mine continues to generate press and pulse disturbances that impact the resilience of the community. Operating from the standpoint that resilience depends largely upon the management capacity of stakeholders, the research identifies three ways to improve mining governance in Itabira. First, there is a need for local government to have more power in dealings with the corporation. Concurrent with this power, however, the municipality must demonstrate ownership over its fate, ideally through the creation of a sustainability plan. Finally, all key parties must demonstrate commitment to cooperating to resolve outstanding disturbances, even when these fall outside the regulatory approval process. While Itabira will remain a mining town for the foreseeable future, actions taken now to address challenges will only strengthen community wellbeing and sustainability moving forward.Item Government and voluntary policymaking for sustainability in mining towns : a longitudinal analysis of Itabira, Brazil.(2013) Fonseca, Alberto de Freitas Castro; Fitzpatrick, Patricia; McAllister, Mary LouiseThe socio-economic fabric of single-company mining towns needs to be carefully considered by both Government and companies in sustainability policymaking. Policy design and effectiveness in such towns are significantly impacted by the city’s economic dependence on a single company.This paper explores the perceived effectiveness of government and voluntary private sector mining policies for pursuing sustainability in the historic mining town of Itabira, Brazil over a period of 20 years. Itabira serves as a worthwhile case study because it allows for an in-depth and longitudinal analysis that can reveal valuable lessons to policymakers of different sectors and jurisdictions located elsewhere. Based on extensive face-to-face interviews and literature reviews, study results indicate that changes to the state environmental licensing policies in the 1990s led to significant socio-environmental improvements in the area. The globalization of the mining company also contributed to an increase in the quantity and quality of voluntary industry policies. Recent technological improvements in the beneficiation processes of the mining company promises to extend the life of the mine to 2050. Although there are significant incremental socio-environmental policies and programmes, sustainability remains an elusive vision in Itabira, with no clear objectives or monitoring and accountability mechanisms. The paper concludes by recommending a more formal integrated policymaking framework.Item Sterile clay pozzolans from phosphate mining.(2015) Matos Neto, José Afonso de; Resende, Domingos Sávio de; Silva Neto, João Trajano da; Gouveia, Antônio Maria Claret de; Aguilar, Maria Teresa Paulino de; Bezerra, Augusto Cesar da SilvaThe work presents the characterization of clays from sterile mining of the concentrated phosphatic materials of Araxá in Minas Gerais as pozzolanic materials. Three clays of distinct tones, namely, yellow (YC), red (RC), and intermediate (IC) clays, were used at different levels of excavation depth. The clays were calcined at three temperatures (680, 760, and 840 °C) in a muffle-type electric oven. The pozzolanic activity levels of the calcined clays was measured through the conductivity change in saturated Ca(OH)2 solutions and also from the result of the compressive failure load achieved by mortars with 35% of the Portland cement replaced with the calcined material. The results indicated that the calcined clays showed a high level of pozzolanic activity and can be used as a partial substitute for Portland cement, thus suggesting the possibility of recovering this sterile material.Item Impact of quality of iron ore lumps on sustainability of mining operations in the Quadrilatero Ferrifero Area.(2015) Gomes, Reinaldo Brandão; Tomi, Giorgio Francesco Cesare de; Assis, Paulo SantosThe quality of lumps may have a significant impact in iron ore mining systems with implications for mineral reserve recovery rates. Improving the quality of lump ore, through a simple yet innovative mineral processing, can maximize recovery of reserves, decrease waste generation, and increase the productivity and sustainability of mines by allowing transition to lower quality iron ores. An example of the application of such principle is described here in which both siliceous and dolomitic banded iron formation rocks (BIFs) were subjected to chemical, physical, and mineralogical characterization before undergoing beneficiation processes in pneumatic jigs and log washer equipment. These processes were found to increase product quality and reduce the levels of contaminants, including SiO2, Al2O3, and fines. The gain in quality led to a reduction in the cut-off grade, from 60% to 58% Fe, while maintaining products specifications. Consequently, a 20% increase in the lump ore reserves was achieved, contributing to the sustainability of the mining system.