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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Selective flocculation and floc-flotation of iron bearing mineral slimes.
(2022) Bretas, Pedro Lopes; Rodrigues, Otávia Martins Silva; Luz, José Aurélio Medeiros da
The mineral processing of friable iron ores usually generates ultrafine (smaller than 15 μm) particles, normally called slimes, which usually have a high iron grade and are usually disposed into tailings dam. The traditional mineral process techniques for iron ore do not work efficiently with ultrafines; however, selective flocculation is an alternative to concentrate that fraction. The physical-chemical treatment of iron ore slime was studied here, on a bench scale, based on the scientific foundations of selective flocculation and flotation. Samples of slimes from two Brazilian iron ore processing plants (CEII and VGII) and industrial process waters were used in the tests. Complexometric titration of calcium and magnesium indicated that the process waters were adequate for selective flocculation. Only selective flocculation, even under optimum conditions, did not achieve good results. However, its use prior to flotation led to promising results. The VGII sample has stood out, for which the final concentrate achieved 60.1 % of Fe, the mass recovery was 64.5 % and 13.5 % of Fe in the tailing, resulting selectivity index of 6.58, only with one stage of selective flocculation and one stage of flotation.
Characterization and concentration by selective flocculation/magnetic separation of iron ore slimes from a dam of Quadrilátero Ferrífero – Brazil.
(2020) Lima, Rosa Malena Fernandes; Abreu, Francisco de Paula Vitor Fonseca
In this paper the results of size, chemical and mineralogical characterizations as well as the concentration tests performed with a slimes sample of iron ore from a dam at the Quadrilátero Ferrífero in the state of Minas Gerais, Brazil are presented. The sample was constituted by 75 % of slimes (particles –10m). The main minerals identified by X-ray diffractometry and thermal analysis were: goethite, hematite, quartz and kaolinite. The sample grades were: Fe (∼51.4 wt.%.), SiO2 (∼15.1 wt.%), Al2O3 (∼3.4 wt.%), P (0.097 wt.%) and LOI (∼7 wt.%). During the optimized bench testing condition of selective flocculation/magnetic separation (pH = 10.5, sodium silicate and corn starch =50 g/ton, magnetic strength =3575 G) by experimental statistical planning design, the mass recovery was of 48.4 %. There was an increase of 8 % in Fe grade and a decrease of 50 % in both SiO2 and Al2O3 grades when compared with the feed. Agglomeration studies with the obtained concentrate will be performed in future.
Proposal for an environmentally sustainable beneficiation route for the amphibolitic Itabirite from the Quadrilátero Ferrífero - Brazil.
(2020) Gonçalves, Gizele Maria Campos; Lima, Rosa Malena Fernandes
The high world demand for iron ores opposed to the rapid exhaustion of high-grade deposits from the main producing regions around the world has motivated the search and/or improvement of beneficiation routes, which enable the economic use of iron formations previously considered marginal ores, which have the potential to considerably increase mineable reserves due to their large volume. In this study, a sample of amphibolitic itabirite from the eastern region of the Quadrilátero Ferrífero, minas Gerais, Brazil was characterized, aiming at its use in the industrial pelletizing circuit. The main physical characteristics of this ore are moisture = 10% and specific weight = 3710 kg/m3 . The ore has a high grade of loss on ignition—LOI (6.7%) and P (0.14%). Through X-ray diffractometry (XRD), optical microscopy and scanning electron microscope—SEM, the ore was found to consist of 64.5% goethite (amphibolitic, alveolar, massive and earthy); 6.8% hematite (martitic, granular and lamellar) and 0.9% magnetite. The main gangue mineral is quartz (25.5%). Based on the results of concentration tests (magnetic and flotation) performed with the studied sample, the magnetic concentration route of deslimed sample followed by the addition of slimes in magnetic concentrate can be incorporated into the pelletizing process.
Effect of binder and drum speed on hematitic fines balling.
(2021) Cunha, Fernando Rodrigues da; Luz, José Aurélio Medeiros da; Neuppmann, Pedro Henrique
Determination of the physical properties of pellets is of great industrial importance since they are parameters that will allow a better use of the fines in the plants. Several studies relating different process variables with the pellet properties produced can be found in the literature, but it is still very difficult to predict the particle size distribution of the agglomerates of a new formulation only with the knowledge of its properties. In this study, the ore characterization was performed, evaluating the effect of the rotational speed of the drum and the performance comparison between two binders during green pellets granulation. Decrease of average diameter of the pellets with the use of a carboxymethylcellulosebased binder (Peridur 330, 0.4 kg/t ratio) was observed, in comparison with the conventional binder, bentonite (5 kg/t ratio). Bentonite-containing mixture has showed slightly lower porosity and lower permeability, also indicating a higher resistance of the pellets formed.
Correlations of rock mass classifications applied to ferruginous caves.
(2020) Oliveira, Paula Cristine Leal; Lima, Hernani Mota de
For the Brazilian iron ore mines, the presence of caves presents a challenge, since most of them are located within the ore deposit. The National Environment Commission (CONAMA 347 Resolution/2004) establishes that the speleological heritage, as well as its area of influence, cannot sustain irreversible environmental impacts. The physical integrity of caves adjacent to mining operations is an issue of pivotal importance to be scrutinised in studies towards the delimitation of the cave’s protection radius. This article presents the study of various models of correlation between the RMR and Q systems used for the stability assessment of natural iron ore caves. In order to study a correlation between the RMR and Q systems, the most popular rock mass classifications, and their application as a validation tool, a selection of measurements of Q and RMR, organized in a database from seven natural caves of ferruginous lithology, are submitted to a study and statistical analysis. An empirical equation was obtained from the data, using a simple linear regression. The result of the regression was compared with selected correlation equations and the best fit for the data was chosen. The best fit was the Rutledge & Pearson correlation equation, which presented the best combination of R² and S, after the equation created on basis of the real values for RMR, though the other equations have results similar to it. As the results were quite similar, the recommendation still is that correlations should be used with caution, and associated to other methods and field analysis.
Análise de agrupamento aplicada ao reconhecimento de diferentes tipos de itabiritos silicosos friáveis da Mina de Brucutu.
(2019) Gonçalves, Gizele Maria Campos; Rocha, Geriane Macedo; Barreto, Paula Bernardes; Pereira, Tiago Martins; Lima, Rosa Malena Fernandes
A análise de agrupamento é uma técnica de estatística multivariada que permite separar as unidades amostrais em grupos homogêneos internamente e heterogêneos externamente. Neste estudo essa técnica foi aplicada, através do software R, com o objetivo de estratificar em subgrupos os minérios classificados como itabiritos silicosos friáveis da Mina de Brucutu, Quadrilátero Ferrífero-MG. A matriz de dados era composta por 3.519 amostras e 10 variáveis granulométricas e químicas. A análise hierárquica de agrupamento mostrou que as amostras podem ser subdivididas em quatro grupos, e então, as mesmas foram agrupadas pelo método não hierárquico K-means. Através da análise das características de cada grupo formado, os mesmos foram classificados e relacionados com a geologia da jazida. A Tipologia 1 (itabirito silicoso friável rico e fino), é localizada no topo do depósito e estratigraficamente acima das rochas intrusivas máficas. A Tipologia 2 (itabirito silicoso friável pobre e grosseiro) é marcado pela direção NW-SE, evento Brasiliano. A Tipologia 3 (itabirito silicoso friável pobre e fino) é dispersa ao longo do depósito, dificultando sua correlação com alguma fase geológica. A Tipologia 4 (itabirito semi-compacto pobre) concentra-se na região SW do depósito.
Instrumented geotechnical monitoring of a natural cave in a near mine operation – towards a sustainable approach to mining and preservation of speleological heritage.
(2019) Brandi, Iuri Viana; Barbosa, Marcelo Roberto; Paula, Rafael Guimarães de; Araújo, Ramon Nunes; Moura, Rafael Simões Vieira de; Lima, Hernani Mota de
The iron ore mining in Brazil is currently restricted due to federal laws for natural caves protection. Four classes of cave relevance are formally designated based primarily on geological and biospeleological criteria. According to the law, Maximum Relevance caves must be protected, together with a 250 m buffer zone. This protection zone, on the other hand, blocks substantial iron ore reserves that impacts mining projects feasibility and postpones or discontinues several ones. This 250 m buffer zone has a preliminary status and can be increased or reduced according to the results of specific long-term studies that ensure caves’ physical integrity, as well as the maintenance of its ecological balance. Considering the need to preserve the natural caves and to conduct a sustainable mining operation, this paper presents the geotechnical monitoring methodology used to anticipate instabilities in the cave, as well as to optimize the study time, considering an approach through remote instrumentation. A pilot project with operations within the 250 m protected zone of a natural cave was conducted at the iron ore mine N4EN, in Carajas, Brazil. Strain and convergence measurements were conducted on the weaknesses points/zones within the caves, identified during geostructural-geotechnical mapping. The data collected were continuously transmitted via web in real time to a database server; automatically treated and turned into updated reports and control charts available on the Internet from an expert software. The results demonstrated the applicability of remote geotechnical techniques for monitoring the structural stability of caves near mining operations, even when subjected to seismic waves, generated by regular blasting. This approach has contributed to the sustainability of the operations that reached a distance of 75 m from the studied cave that remained stable and with its speleological balance and functionality.
Error variance of short duration sieving.
(2018) Resende, Tulio Viegas Bicalho; Luz, José Aurélio Medeiros da
n this study, the variance of ordinary sieving test error was determined concerning the specification limit of sized iron ore product by subtracting the fundamental error (described by the Gy's formalism for sampling), from the global error (recoverable from database of historical values). The results allowed the calculation of the confidence interval for the percentage of material finer than the upper screen specification limit. Thereafter, a method to estimate the so-called effectiveness coefficient of the screening operation was developed, which is the ratio between number of particle presentations to passage and the number of oscillations during the material shaking on the screen surface. This estimation was based on the probability statements and particle size distribution of the feed. Considering the size distribution of the products tested in this study, the results have shown that the sieving time could be reduced when determining the percentage of material finer than the upper specification mesh.
Effect of EDTA on quartz and hematite flotation with starch/amine in an aqueous solution containing Mn2+ ions.
(2016) Lelis, Deisiane Ferreira; Leão, Versiane Albis; Lima, Rosa Malena Fernandes
In this paper, a detailed study of the influence of Mn2+ ions on quartz and hematite flotation (at pH 10.5 with starch/amine as depressor/collector) in the absence and presence of ethylenediaminetetraacetic acid (EDTA) is presented. By using zeta potential measurement and a careful analysis of manganese species present in water for dosages in which manganese hydroxide precipitated, we confirmed that the depression of both minerals by Mn2+ ions is due to the following: (i) the adsorption of Mn hydroxy complexes (Mn2(OH)3+ and Mn(OH)+); (ii) Mn2+ and mainly (iii) the precipitation of Mn(OH)2 on mineral surfaces. These effects hindered the adsorption of amine species on the surfaces of the minerals (quartz and hematite). EDTA was used to complex Mn2+ to restore the recoveries of both minerals. This was confirmed by the species distribution diagrams of Mn and EDTA–Mn in water. Conditioning with starch followed by amine at pH 10.5 enabled a selective separation of these minerals.
Multi-scale approach using remote sensing images to characterize the iron deposit N1 influence areas in Carajás Mineral Province (Brazilian Amazon).
(2012) Morais, Maria Carolina de; Martins Júnior, Paulo Pereira; Paradella, Waldir Renato
Mining activities cause a wide range of changes to the environment, substantially affecting both the physical and biological environmental sectors. In the Caraja´s Mineral Province, located in the Amazon rainforest, environmental regulations tend to be more rigorous, due to the fragility of the environment in which large iron deposits are found. The characterization of the impact of mining on environment considers: the type and extent of the impact, the physical chemistry differences and similarities of the mineral deposits, the deposit size, the adopted mining process, and the environment (both natural and economic) in which the mining process was developed. Remote sensing technology is utilized in this study, in particular, the use of ortho-aerial photograph, and optical and radar images with distinct spatial resolution. These permit the elaboration in synoptic maps, multi-scale and dynamic, of the changes wrought upon the environment: deforestation, removal of vegetation cover, topographic surface and landscape alteration, and slope instabilities among others. In this aspect, determining the extent of influence of the mining activity is directly tied to the characterization of its impact on various natural systems at the observed scale, and not by simply defining a predetermined Euclidean distance. The results showed that remote sensing technology, optical and radar images, proved to be efficient in the study of environmental information and the areas of influence on the semi-regional and local scales in the Amazon forest.

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