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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2013 - 201972020 - 20212

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Autor: search.filters.author.Fontes, Wanna CarvalhoTem arquivos: Sim

Resultados da Pesquisa

Agora exibindo 1 - 9 de 9
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    Enhancing the eco-efficiency of concrete using engineered recycled mineral admixtures and recycled aggregates.
    (2020) Carvalho, José Maria Franco de; Fontes, Wanna Carvalho; Azevedo, Carlos Felipe de; Brigolini, Guilherme Jorge; Schmidt, Wolfram; Peixoto, Ricardo André Fiorotti
    Non-conventional densely packed concrete mixtures are proposed and evaluated in this paper using engineered recycled mineral admixtures and recycled aggregates obtained from steel slag, quartz mining tailings, and quartzite mining tailings. High fines content sand-concretes containing coarser- and finer- than-cement recycled powders were designed to obtain blends with broader particle-size ranges and improved packing density. As a result, compressive strength up to 99 MPa, cement intensity up to 2.33 kg/m3 /MPa, and consumption of recycled material up to 95 vol% were obtained. Compressive strengths up to 66 MPa and cement intensity up to 2.34 kg/m3 /MPa were also obtained with the addition of coarse aggregates to such sand-concrete mixtures, with consumption of recycled material up to 96.5%. The results launch new insights on the role of recycled admixtures and aggregates on the mixture design of cement-based composites regarding efficiency improvement and technological performance.
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    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 Fiorotti
    Confronted 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.
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    Assessment of the use potential of iron ore tailings in the manufacture of ceramic tiles : from tailings-dams to ‘‘brown porcelain”.
    (2019) Fontes, Wanna Carvalho; Carvalho, José Maria Franco de; Andrade, Luana Caetano Rocha de; Segadães, Ana Maria Bastos Costa; Peixoto, Ricardo André Fiorotti
    Nearly half of the total iron ore volume extracted in mining operations is rejected as tailings and disposed of in containment dams that are liable for considerable environmental impact and human hazard in case of breaching. This work aims to expand the usage possibilities of iron ore tailings and help mitigate the negative impact of tailings-dams without sacrificing the opportunities provided by mining. Materials were collected from four tailings-dams, subjected to a dry separation procedure and characterized (particle size and morphology, chemical and mineralogical composition). Besides the recovered iron ore concentrate, two other powder fractions were produced (“clay” and “sand” fractions). The sands showed the greatest uniformity (particle size and shape, mineralogy and chemical composition) and may find use as aggregates in a variety of applications. This work shows that the clays can be used on their own in the production of ceramic tiles. They present adequate plasticity and dry strength, and develop mullite and glass upon firing, showing a rather amenable processing behaviour suitable for both artisanal and full-fledged industrial production. The resulting tiles are dimensionally homogeneous and very compact (vitrified products, classified in groups BIa, BIb or BIIa), with high mechanical strength. Either industrialised or artisanal, these materials can be used in the production of “brown porcelain” tiles and ware, showing a very appealing dark brown lustre.
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    More eco-efficient concrete : an approach on optimization in the production and use of waste-based supplementary cementing materials.
    (2019) Carvalho, José Maria Franco de; Melo, Tainá Varela de; Fontes, Wanna Carvalho; Batista, Júnio Oliveira dos Santos; Silva, Guilherme Jorge Brigolini; Peixoto, Ricardo André Fiorotti
    This paper presents a study that includes increase in clinker replacement and waste consumption in cement-based composites. Techniques for performance optimization of waste-based supplementary cementing materials in densely packed matrices using basic oxygen furnace slag, iron ore tailings from a tailings dam, quartz mining tailings and quartzite mining tailings were evaluated. Powders with different particle size ranges were produced and characterized. A highly-packed sand-concrete reference mix was designed and six different mixtures with 10−60 vol% partial cement replacement were evaluated. The high binder efficiencies observed and physical-mechanical performances evidence the effectiveness of the proposal, expanding the concept of low-cost supplementary cementing materials and broadening the range of residual materials suitable for use in cement-based composites.
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    Iron ore tailings in the production of cement tiles : a value analysis on building sustainability.
    (2018) Fontes, Wanna Carvalho; Fontes, Giovanni Gonçalves; Costa, Ellen Cristine Pinto da; Mendes, Júlia Castro; Silva, Guilherme Jorge Brigolini; Peixoto, Ricardo André Fiorotti
    The present work discloses the development of a sustainable cement tile (SCT) produced with Iron Ore Tailings from tailings dams (IOT). Initially, technical evaluation and environmental analysis of IOT were performed through physical, chemical and morphological characterisation, leaching and dissolution tests. Its feasibility as a pigment was also investigated. Subsequently, the value analysis was performed, starting from an empathy map to a study on environmental, social and emotional values in the relationship between people and product. As result, the IOT presented fine, crystalline particles, no toxicity, and is technically feasible to be employed as filler, aggregate and pigment in the production of SCT. The colour layer of the SCT presented more homogeneous colour and less pores than conventional ones. Therefore, the design of the SCT was developed, incorporating intangible values such as: environmental ideology, local identity and social expression. In this sense, the present work seeks to assist in the decision-making process involving IOT as construction material.
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    Studies on the use potential of iron ore tailings as alternative raw material in manufacture of ceramic and hydraulic tiles.
    (2018) Fontes, Wanna Carvalho; Peixoto, Ricardo André Fiorotti; Silva, Guilherme Jorge Brigolini; Arcipreste, Cláudia Maria; Santos, White José dos; Aguilar, Maria Teresa Paulino de
    Iron ore mining is a very important economic activity to Brazil. The increase in tailings generation, as well as its inadequate waste disposal, has awakened concerns over the sustainability of its processes, mainly due to the environmental impacts and socioeconomic risks associated with tailing dams. On the other hand, the reuse of the tailings in building materials can contribute to the sustainable consumption of resources, mitigation of the negative environmental impacts, new market opportunities and the aggregation of values to the companies. This study aims assessment of the potential use of iron ore tailings as an alternative raw material in the production of ceramics and cement tiles. The materials were collected from four tailings-dams and an part was subjected to a dry separation procedure. Besides the iron ore, two other powder fractions were produced (“clay” and “sand” fractions). The clay, sand, and residual iron ore concentrate were characterized (particle size and morphology, chemical and mineralogical composition). The residual iron ore concentrate showed fine, crystalline, and dense particles, no toxic, suitable technically for use as addition and aggregate in the production of terracotta cement tiles. The sands showed the greatest uniformity (particle size and shape, mineralogy and chemical composition) which contributed to the compressive strength gains of the cement composites. The clay present adequate plasticity and dry strength, and develop mullite and glass upon firing. Despite the greatest firing shrinkage (between 22.59 and 26.51%), the resulting tiles show a appealing dark brown luster and are very compact (vitrified products, classified in groups BIa, BIb or BIIa), with high mechanical strength.
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    Evaluation of the economic feasibility of a processing plant for steelmaking slag.
    (2016) Gonçalves, Deyvid Ricardo Ramos; Fontes, Wanna Carvalho; Mendes, Júlia Castro; Silva, Guilherme Jorge Brigolini; Peixoto, Ricardo André Fiorotti
    The utilisation of steelmaking slag as recycled aggregate for concretes is a widely investigated solution for mitigating the expenditure and environmental impacts of its storage. The Brazilian steel industry is investing in research and slag reprocessing practices, aiming to reuse most of its metallic fraction and properly allocate the non-metallic fraction, saving energy and reducing mining impacts. Research results demonstrate the technical and environmental feasibility of steel slag aggregates for civil construction. However, it is essential to evaluate whether the processing of the slag is economically feasible for this purpose. Economic analysis of the processing of steel slag was conducted through simulation – Monte Carlo method – in which it is possible to determine the risks and uncertainties inherent to the project. The costs that comprise the proposed project, from design through construction and operation itself, were estimated at US$2.8 million. The result of the simulation indicates economic feasibility of the project with 98% certainty, and an estimated profit of around 42%.
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    Mortars for laying and coating produced with iron ore tailings from tailing dams.
    (2016) Fontes, Wanna Carvalho; Mendes, Júlia Castro; Silva, Sidney Nicodemos da; Peixoto, Ricardo André Fiorotti
    Aiming to mitigate the environmental impact of the iron mining industry, this paper evaluates the technical feasibility of using iron ore tailings from tailing dams (IOT) as construction material, for mortars for laying and coating. Three mixtures were produced: conventional mortars, mortars with complete replacement of natural aggregate by IOT, and mortars replacing lime by IOT in proportions from 10% to 100%. IOT and mortars were characterised. Mortars with IOT showed increased bulk density, reduced levels of incorporated air, an increment in the amount of mixing water, and improved mechanical properties when compared with conventional ones.
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    Utilização do rejeito de barragem de minério de ferro como agregado reciclado para argamassas de revestimento e assentamento.
    (2013) Fontes, Wanna Carvalho; Peixoto, Ricardo André Fiorotti
    Atualmente, a busca por soluções inovadoras e sustentáveis torna-se imprescindível diante do grande consumo de recursos naturais pelo setor da construção civil. Perante esta realidade, o presente trabalho aborda o uso do rejeito de barragens de minério de ferro (RBMF) como matéria-prima para produção de matrizes de argamassa para revestimento e assentamento de alvenarias, aplicadas em obras civis e construções metálicas. Objetiva-se, assim, contribuir para a redução dos passivos ambientais, representados por essas barragens de rejeito, diminuindo proporcionalmente as possibilidades de ocorrência de desastres ambientais, bem como os custos operacionais de manutenção, segurança e monitoramento dessas estruturas. Neste contexto foi necessária a verificação da viabilidade técnica das argamassas propostas pela realização de ensaios laboratoriais, procedidos de acordo com a normatização brasileira. Desta forma, foram realizadas as análises físicas, químicas, mineralógicas, microestruturais e ambientais para a caracterização completa do rejeito de minério de ferro. As argamassas foram dosadas segundo proporção 1:3, com agregados naturais, reciclados, cimento e cal. Foram produzidos traços com substituição da cal por rejeito nas proporções 0%, 10%, 20%, 50% e 100% para as idades de 3, 7 e 28 dias. Em sequência, as argamassas foram submetidas a ensaios, no estado fresco e endurecido, sendo possível assim classificá-las conforme as características e propriedades de interesse da engenharia. Também foram procedidas análises da viabilidade ambiental e econômica, a fim de estimar as perspectivas de desempenho dos produtos obtidos. Os resultados alcançados permitiram avaliar que é possível usar o rejeito (RBMF) como matéria-prima de forma técnica e ambientalmente adequada para a redução dos impactos ambientais da mineração com a produção de argamassas com agregados reciclados (RBMF).