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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Filtros

2017 - 201912020 - 20221

Configurações

Autor: search.filters.author.Lima, Rosa Malena FernandesAssunto: search.filters.subject.Dolomite

Resultados da Pesquisa

Agora exibindo 1 - 2 de 2
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    Concentration of oxidized Brazilian zinc ore by flotation : comparative study between anionic and cationic routes.
    (2022) Ferreira, Pedro Henrique Tófani; Lima, Rosa Malena Fernandes
    In this work, a mineralogical characterization by X-ray diffractometry and thermogravimetric analysis of a new Brazilian zinc ore sample was performed. The mineralogical semi-quantification, conducted by normative calculation of the identified minerals, using their theoretical chemical formulas and the contents determined in the chemical analyses was as follows: smithsonite (20.3%), goethite (49.6%), kaolinite (12%), quartz (6.2%), cerussite (3.0%), chlorite (4.0%), dolomite (0.5%) and others (4.4%). Subsequently, bench flotation tests were executed, using sodium oleate (anionic route) and amine (cationic route) as smithsonite collectors. Sodium silicate was used as a depressant of the gangue minerals in both routes tested. These studies showed that the anionic route (30.1% Zn in concentrate and 83% Zn recovery) performed better than the cationic route (17.5% Zn in concentrate and 46.3% Zn recovery). Considering the mineralogical composition of the concentrates obtained in the best flotation results, associated with physicochemical studies published in the literature with the identified minerals, it was evidenced that the difference in performance between the tested routes is due to the influence of ions from the dissolution of carbonates present in the ore on the surface properties of the main gangue minerals (goethite and silicates), especially for the cationic route.
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    Influence of cations Ca2+, Mg2+ and Zn2+ on the flotation and surface charge of smithsonite and dolomite with sodium oleate and sodium silicate.
    (2017) Araújo, Ana Carolina Arantes; Lima, Rosa Malena Fernandes
    using sodium oleate and sodium silicate. Microflotation test results demonstrated recoveries of 95% and 5% for smithsonite and dolomite, respectively, from 2.5 × 10−5 M sodium oleate and 50 mg/L sodium silicate at pH 9.5. The smithsonite was depressed by the cations Ca2+ and Mg2+ and, the dolomite was depressed by Zn2+ cations, which was probably caused by the reaction of these cations with the oleate anions in the solution, decreasing the concentration of collector available for adsorption onto the minerals. The powerful depression of smithsonite caused by Ca2+ cations compared with that caused by Mg2+ cations can be considered to have occurred because of the higher concentration of Ca2+ in the solution. From the zeta potential measurements at pH 9.5, we concluded that the predominant species of oleate and of sodium silicate were adsorbed onto both minerals, and the silicate species prevented the adsorption of oleate anions onto dolomite. The decrease in the negative zeta potential of both minerals after cation conditioning can be related to the electrostatic attraction between the cations and the negative sites on their surfaces. The negative zeta potential of smithsonite increased at a concentration of 1 × 10−6MCa2+ and Mg2+,whereas the potential decreases at a concentration of 1 × 10−3 M, which can be related to a lower concentration of oleate anions being available for adsorption.