The Itabirites of the Quádrilátero Ferrífero and Related High-Grade Iron Ore Deposits: An Overview

Rosière, Carlos Alberto; Spier, Carlos Alberto; Ríos, Francisco Javier; Suckau, Viktor E.

doi:10.5382/rev.15.09

Cited by 35 publications

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“…Natural samples We use BIF samples from the district of Itabira, in the northeastern region of Quadril atero Ferrífero (MG -Brazil) (e.g. Rosi ere et al, 2001Rosi ere et al, , 2008, exhibiting layers with different proportions and distributions of quartz and hematite. Individual layers show thicknesses from few millimeters to centimeters and tabular to lens shape.…”

Section: Methodsmentioning

confidence: 99%

The effects of quartz recrystallization and reaction on weak phase interconnection, strain localization and evolution of microstructure

Gonçalves

Hirth

2015

Journal of Structural Geology

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We conducted axial compression and general shear experiments, at T ¼ 900 C and P ¼ 1.5 GPa, on samples of banded iron formation (BIF) and synthetic aggregates of quartz, hematite and magnetite to investigate how dynamic recrystallization of quartz promotes strain localization, and the role of weak second phases (oxides) on the rheology and microstructural evolution of the aggregates. Experiments showed strain localization into oxide rich layers, and that the oxide content and oxide distribution are key factors for the strength of the aggregate. Only 2e10 wt.% hematite leads to pronounced weakening and increasing hematite content above~10% has only a minor additional effect. Where oxide grains are dispersed, the initial strength contrast with quartz induces stress concentrations at their tips, promoting high stress recrystallization-accommodated dislocation creep of quartz. Fine recrystallized quartz reacts with oxide, forming trails of fine reaction product (ferrosilite/fayalite) leading to the interconnection/ percolation of a weaker matrix. The strength contrast between the quartz framework and these finegrained trails promotes strain localization into micro-shear zones, inducing drastic strain weakening. Thus dynamic recrystallization of quartz promotes syn-deformational reactions leading to a microstructurally-controlled evolution of phase strength contrast. It results in a rheologic transition from load-bearing framework to a matrix-controlled rheology, with transition from SeC 0 to SeC fabric with increasing strain.

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Section: Methodsmentioning

confidence: 99%

The effects of quartz recrystallization and reaction on weak phase interconnection, strain localization and evolution of microstructure

Gonçalves

Hirth

2015

Journal of Structural Geology

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“…Metamorphic and weathering processes provided the enrichment of iron that exceeds 60% wt. Fe (Spier 2005, Rosiere et al 2008). The Figure 6 shows the Fe distribution in stream sediments and the main Fe deposits in IQ region.…”

Section: Iron Depositsmentioning

confidence: 99%

Geochemical Mapping of Iron Quadrangle region by active stream sediments, State of Minas Gerais, Brazil

Larizzatti¹,

Marques²,

Silveira³

2018

Geochim. Bras.

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RESUMOO mapeamento geoquímico do Quadrilátero Ferrífero foi realizado pela CPRM -Serviço Geológico do Brasil com dados geoquímicos de uma área de 45.000 km 2 entre os meridianos 42 o 30´W e 45 o W e paralelos 19 o 30´S e21 o S. Sedimento ativo de corrente na fração < 80# (ou 0.175 mm), foi pulverizado a < 150# (~0,100 mm), digerido com água régia quente e analisado para 53 elementos (ICPMS). Foram elaborados mapas uni-e multi-elementares. Sedimento de corrente é um meio efetivo no mapeamento geoquímico regional. Estruturas geoquímicas, unidades litológicas e processos de mineralização foram reconhecidos com a densidade de amostragem de 1 amostra por 12 km 2 . A densidade de amostragem é um fator chave na qualidade dos mapas geoquímicos produzidos. Deve-se tomar cuidado na interpretação dos resultados devido à sua natureza; estes dados não identificam anomalias geoquímicas específicas ou depósitos minerais individuais. A interpretação dos sedimentos de correntes não é direta e os processos secundários envolvidos na evolução deste material devem ser considerados. Estes dados podem ser usados na exploração mineral para se delinear alvos favoráveis para estudos mais detalhados. Depósitos minerais muitas vezes ocorrem em provinciais geoquímicas caracterizadas por elevadas concentrações de elementos de interesse econômico e farejadores. Depósitos minerais tendem a se localizar ao longo de unidades estratigráficas específicas e/ou trends estruturais por grandes áreas. Estes dados geoquímicos podem ser utilizados em estudos ambientais, apoiar tomadores de decisão na definição de políticas públicas e no manuseio sustentável do solo. Palavras-Chave: mapeamento geoquímico, sedimento de corrente, Quadrilátero Ferrífero, exploração mineral, mapeamento geológico ABSTRACTThe geochemical survey of Iron Quadrangle was performed by the Geological Survey of Brazil -CPRM involving geochemical data from the area between 42 o 30´W and 45 o W and 19 o 30´S and 21 o S, totalling 45.000 km 2 . Active stream sediment was analyzed. Fine fractions (< 80# or 0.175 mm) were pulverized to -150# fraction (~ 0.100 mm), digested by hot acqua regia and analyzed for 53 elements by ICPMS. Maps of raw and manipulated data (element concentrations and multi-elemental scores) were made. Stream sediment (< 80# fraction) is an effective sampling medium for regional geochemical surveys. Geochemical structures, lithological units and mineralization processes were recognized with the sample density of 1 sample per 12 km 2 . Sample density has a key role in the quality of the geochemical maps produced. Caution must be taken when interpreting the results because of its nature; these data do not necessarily pinpoint specific geochemical anomalies or single ore deposits. The interpretation of stream sediment samples is not straightforward and must take into account secondary processes involved in the evolution of sampling media. These data may be used in mineral exploration to delineate favorable targets for more detailed studies. Mineral deposits often occur in...

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“…The dolomitic BIF is the main overburden material of iron ore exploitation at the Conceição mine (Itabira, Minas Gerais, Brazil). It has a similar texture of the siliceous BIF, with alternating bands of carbonate and iron, composed of dolomite, hematite and smaller quantities of quartz, and may also contain varying amounts of calcite, talc, chlorite and amphiboles (Rosière et al, 2008).…”

Section: Methodsmentioning

confidence: 99%

Dolomitic BIF beneficiation of Conceição - MG mine

2019

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In the Conceição-MG mine, there are significant reserves of dolomitic itabirite, which is considered overburden material. This study aimed to develop a flotation route for the concentration of this dolomitic BIF according to the requirements of the steel industry. The characterization of samples, comminution, liberation size, microflotation of the pure dolomite and hematite minerals were performed to establish the conditions for selective separation in bench flotation tests. The microflotation tests showed that the soybean oil at pH 6 preferably floats the dolomite in relation to the hematite. The corn starch depressant at a pH higher than10 preferably depresses the hematite relative to the dolomite. The bench flotation tests revealed interactions between the factors pH, percentage of solids in the pulp, soybean oil and starch dosage. The optimal results for bench flotation tests were achieved under the following conditions: pH at 10.5, percentage of solids of 27wt%, dosages of soybean oil and corn starch of 400g/ton and 351g/ton, respectively.

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The Itabirites of the Quádrilátero Ferrífero and Related High-Grade Iron Ore Deposits: An Overview

Cited by 35 publications

References 0 publications

The effects of quartz recrystallization and reaction on weak phase interconnection, strain localization and evolution of microstructure

The effects of quartz recrystallization and reaction on weak phase interconnection, strain localization and evolution of microstructure

Geochemical Mapping of Iron Quadrangle region by active stream sediments, State of Minas Gerais, Brazil

Dolomitic BIF beneficiation of Conceição - MG mine

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