MORPHOLOGICAL CHARACTERISTICS OF MAGNETITE AND QUARTZ IN THE PRODUCTIVE STRATA OF NORTHERN DISTRICT OF KRYVYI RIH BASIN

2019 ◽  
pp. 28-36
Author(s):  
S. Тіkhlivets
Keyword(s):  
Iron Ore ◽  
Morphological Characteristics ◽  
Northern Region ◽  
Morphological Features ◽  
Iron Formation ◽  
Main Task ◽  
Banded Iron Formation ◽  
Beneficiation Plant ◽  
Geological Processes ◽  
Morphological Studies

Currently, the main task for the geological service of Hannivka deposit of the Northern Ore Mining and Processing Works is to ensure the Ore Mining and Processing Works with raw materials, which allows receiving high-quality iron ore concentrate that meets the requirements of the world market. It is only possible to meet this challenge taking into account the morphological features of the main rock-forming minerals, and as a consequence, the natural capabilities of the ores, their dressability by increasing the efficiency of the blending ores of various mineral varieties and of different technological potential, in order to achieve the optimal composition of the ore mixture, which is fed to the beneficiation plant. Morphological studies of the main minerals in unchanged and metasomatically altered ferruginous quartzites were performed according to the standard method. Measurement of the magnetite and quartz grain sizes was carried out using an eyepiece micrometer mounted on a mineralographic microscope. The determining of their average indexes was carried out with the use of mathematical methods. The results of the study of the main morphological characteristics of iron ore-bearing minerals and their variations, depending on the location within the unchanged and metasomatically altered ferruginous quartz of Hannivka deposits at Northern region are represented. The results of the study of the dihedral angles of magnetite and quartz crystals, changes in the particle size distribution of these minerals, depending on the imposed geological processes on the banded-iron formation of Kryvyi Rig basin are shown. The scientific novelty consists in detailed conducting of mineralogical researches of the magnetite and quartz morphological features depending on their location in the section of the banded-iron formation of the Kryvyi Rih basin and in the further utilization of these results in topominerological mapping of the Northern region. The obtained variability of the main minerals' morphology of the ore-bearing strata must be taken into account in the mineral mapping of the deposit and the Northern region of the Kryvyi Rih basin in general, when specifying the mineral-technological classification of ores and the blended mineral varieties of ores before feeding to the beneficiation plant.

scholarly journals ESTUDOS GEOQUÍMICOS DE ITABIRITOS DA SERRA DO SAPO, ESPINHAÇO MERIDIONAL, MINAS GERAIS

2014 ◽  
Author(s):  
Amanda A. Pires e Souza ◽  
Rosaline Cristina Figueiredo e Silva ◽  
Carlos Alberto Rosière ◽  
Geraldo Sarquis Dias ◽  
Fernando Prudêncio Morais
Keyword(s):  
High Temperature ◽  
Iron Ore ◽  
Morphological Characteristics ◽  
Minas Gerais ◽  
Iron Formation ◽  
Geochemical Analysis ◽  
East Side ◽  
Banded Iron Formation ◽  
Geochemical Studies ◽  
The City

A Serra do Sapo localiza-se na porção leste da Serra do Espinhaço Meridional, nas proximidades do município de Conceição do Mato Dentro, Minas Gerais, Brasil. Nessa região, formações ferríferas bandadas são metamorfizadas e intensamente cisalhadas. De acordo com o grau de intemperismo e compacidade, minérios de ferro com teores entre 31 e 39% Fe são classificados em itabirito, itabirito semifriável e itabirito friável. Cristais de hematita são classificados de acordo com suas características texturais e morfológicas em microlamelar, anédrica, lamelar e martita. Análises químicas de rocha total mostram que os três tipos de itabirito são semelhantes com conteúdo de CaO (≤0,14wt%), MgO (≤ 0,04wt%), MnO (≤ 0,21wt%), Al2O3 (≤ 0,94wt%), K2O (≤ 0,27wt%), TiO2 (≤ 0,05wt%) e P2O5 (≤ 0,11wt%), entretanto com as maiores concentrações de Al2O3, MgO e K2O presentes nos itabiritos semifriável e friável, e as de CaO e P2O5 no itabirito. O teor em U autigênico, e as relações V/Cr e Ni/Co do itabirito apontam para um ambiente de sedimentação oxidante para a formação ferrífera bandada. Razões (Eu/Sm)SN, (La/Sm)CN, (Sm/Yb)SN, (Eu/Eu*)SN, e (Sm/Yb)CN indicam que a formação ferrífera bandada mais fresca, representada pelo itabirito, está livre de contaminação clástica. Já as razões de Sm/Yb vs. Eu/Sm e de Eu/Eu*(CN) vs. (Sm/Yb)(CN) indicam contribuição insignificante por fluidos hidrotermais de alta temperatura.Palavras Chave: Serra do Sapo; Serra do Espinhaço Meridional; Formação ferrífera bandada; Geoquímica. Abstract: GEOCHEMICAL STUDIES OF ITABIRITES FROM SERRA DO SAPO, SOUTHERN ESPINHAÇO, MINAS GERAIS. The Serra do Sapo is located on east side of the southern portion of Serra do Espinhaço, near the city of Conceição do Mato Dentro, Minas Gerais, Brazil. In the area banded iron formation are metamorphosed and slightly sheared. Supergene low to medium- grade iron ore (31 to 39% Fe) are classified in itabirite, semi-friable itabirite and friable or soft itabirite, according to the degree of weathering and compactness. Hematite crystals were classified after their textural and morphological characteristics as: microplaty, anhedral, platy, and martite (pseudomorphic after magnetite). Geochemical analysis show that the three types of itabirites are similar regarding the content of CaO (≤ 0,14wt%), MgO (≤ 0,04wt%), MnO (≤ 0,21wt%), Al2O3 (≤ 0,94wt%), K2O (≤ 0,27wt%), TiO2 (≤ 0,05wt%) e P2O5 (≤ 0,11wt%), with higher grades of Al2O3, MgO and K2O present in semi-friable and friable itabirites and, of CaO and P2O5 in itabirite. The autigenic U, V/Cr and Ni/Co indexes point to an oxic environment of sedimentation. Ratios of (Eu/Sm)SN, (La/Sm)CN, (Sm/Yb)SN, (Eu/Eu*)SN, and (Sm/Yb)CN indicate that the banded iron formation represented by the itabirite is free of clastic contamination and the ratios of Sm/Yb vs. Eu/Sm and of Eu/Eu*(CN) vs. (Sm/Yb)(CN) indicate insignificant contribution of high temperature hydrothermal fluids.Keywords: Serra do Sapo; Serra do Espinhaço Meridional; Banded iron formation; Geochemistry.

Microstructures in a banded iron formation (Gua mine, India)

2007 ◽  
Vol 144 (2) ◽  
pp. 271-287 ◽  
Author(s):  
MANISH A. MAMTANI ◽  
A. MUKHERJI ◽  
A. K. CHAUDHURI
Keyword(s):  
Iron Ore ◽  
Iron Formation ◽  
Eastern India ◽  
Banded Iron Formation ◽  
Rigid Core ◽  
Quartz Veins ◽  
Planar Structures ◽  
Diffusive Mass Transfer ◽  
Ore Minerals ◽  
Deformation Processes

This paper provides a detailed documentation of microstructures developed in the banded iron formation (BIF) of Gua mine, located in the Bonai Synclinorium (eastern India), where the rocks have been subjected to three deformations (D1 to D3). Folded iron ores, quartz strain fringes around rigid core objects and folded iron ore layers, and refracted quartz veins are described from samples taken from D2 folds in the banded iron formation. Orientations of microstructures are compared with mesoscopic structures to interpret the generations of ore minerals, planar structures and the time relationship between deformation and development of different microstructures. The mechanism of D2 folding is worked out and its bearing on microstructure development is discussed. The D2 folds are inferred to have developed by a combination of tangential longitudinal strain in the competent layer, flexural flow in the incompetent layers and flexural slip at the interface between layers of differing competence. Homogeneous flattening strain superposed the earlier strain, which led to modification of the folds in the competent layer from class 1B to 1C. This strain is quantified and is found to be higher in the limb than the hinge of a fold. Diffusive mass transfer by solution and bulging dynamic recrystallization in quartz are inferred as the dominant deformation processes during folding. Moreover, based on comparison with published deformation microstructure maps, the microstructures of the present study are estimated to have developed between 300 and 350 °C temperatures at a strain rate of 10−14–10−12 s−1, which are geologically realistic conditions for naturally deformed rocks.

Tiny particles building huge ore deposits – Particle-based crystallisation in banded iron formation-hosted iron ore deposits (Hamersley Province, Australia)

2019 ◽  
Vol 104 ◽  
pp. 160-174 ◽  
Author(s):  
Mathias S. Egglseder ◽  
Alexander R. Cruden ◽  
Andrew G. Tomkins ◽  
Siobhan A. Wilson ◽  
Hilke J. Dalstra ◽  
...  
Keyword(s):  
Iron Ore ◽  
Ore Deposits ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Iron Ore Deposits

scholarly journals Fluid Inclusion and Oxygen Isotope Characteristics of Vein Quartz Associated with the Nabeba Iron Deposit, Republic of Congo: Implications for the Enrichment of Hypogene Ores

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 677
Author(s):  
Ebotehouna ◽  
Xie ◽  
Adomako-Ansah ◽  
Pei
Keyword(s):  
Iron Ore ◽  
Early Stage ◽  
Laser Raman Spectroscopy ◽  
Iron Formation ◽  
Iron Deposit ◽  
Banded Iron Formation ◽  
Republic Of Congo ◽  
Ore Deposit ◽  
Laser Raman ◽  
Ore Mineralization

The Nabeba iron ore deposit is located at the northern part of Congo Craton, Republic of Congo. The ore deposit consists of supergene and hypogene ores, both of which are hosted in the Precambrian Nabeba banded iron formation (BIF). This study focuses on the hypogene iron ore mineralization associated with quartz veins in the Nabeba deposit, for which two hypogene ore stages have been recognized based on geologic and petrographic observations: early-stage high‐grade hematite‐rich ore (HO‐1) and late-stage magnetite‐rich ore (HO‐2). Based on microthermometric measurements and laser Raman spectroscopy of the fluid inclusions, the H2O‐NaCl ± CO2 fluids interacting with the Nabeba BIF at the HO‐1 stage evolve from high‐to‐moderate temperatures (203–405 °C) and contrasting salinities (moderate-to-low: 1–15 wt. % NaCl equiv.; high: 30–35 wt. % NaCl equiv.) to H2O‐NaCl fluids of moderate‐to‐low temperatures (150–290 °C) and salinities (1–11 wt. % NaCl equiv.) for the HO‐2 ore stage. Assuming equilibrium oxygen isotopic exchange between quartz and water, the δ18Ofluid values range from 4.7–8.1‰ for the HO‐1 stage and −2.3‰ to −1.5‰ for the HO‐2 stage. This implies the ore‐forming fluid of initially-mixed metamorphic–magmatic origin, later replenished by seawater and/or meteoric water during the formation of the HO‐2 stage. These mixtures of different fluids, coupled with their interaction with the BIF lithology followed by phase separation, are responsible for the enrichment of hypogene iron ore in the Nabeba deposit.

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