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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Resultados da Pesquisa
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.