• The Journal of the Petrological Society of Korea
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• v.20 no.2
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• pp.115-135
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• 2011

Fe-Ti ore bodies and mafic granulite occur in the Sancheong anorthosites, south Korea. In order to determine their petrogenetic relationship and to classify the Fe-Ti ore bodies, we have synthetically analyzed characteristics in the field, such as distribution and occurrence, and petrologic features through detailed outcrop sketches. The ore bodies are divided into the regular vein dike- and irregular veinlet swarm types, according to their characteristics of contact with the anorthosites and internal structures. The former shows the tabularly intrusive contact and the pervasively ductile-sheared interior, while the latter, the irregularly tortuous contact and the almost intact interior. Most of the ore bodies are cross-cutting the foliation of the anorthosites and possess abundant anorthositic xenoliths, indicating their intrusion after the formation of foliation in the anorthosites. The mafic granulite, also bearing abundant anorthositic xenoliths, shows interior foliations nearly parallel to intrusion contact, and has abundant ilmenites approximately the same as those of the Fe-Ti ore bodies in chemical composition. And its intrusion into adjacent anorthosites is observed and the intrusion is finally changed into an irregular veinlet swarm type ore body. It is, thus, interpreted that the granulite in the study area was the host material of Fe-Ti ore bodies.

• Economic and Environmental Geology
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• v.50 no.1
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• pp.35-44
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• 2017

The Hadong-Sancheong Proterozoic anorthosite complex occurs in the southwestern region of the Ryongnam massif. The geology of the area mainly consists of metamorphic rocks of the Jirisan metamorphic complex as basement rocks, charnockite, and the Hadong-Sancheong anorthosite, which are intruded by the Mesozoic igneous rocks. Hadong-Sancheong anorthosite complex is divided into the Sancheong anorthosite and the Hadong anorthosite which occur at north-southern and south area of the Jurassic syenite, respectively. The Hadong Fe-Ti-bearing dike-like ore bodies developed intermittently in the Hadong anorthosite with north-south direction and extend about 14 km. The Hadong Fe-Ti-bearing ore bodies consist mainly of magnetite and ilmenite with rutile, titanite, and minor amounts of sulfides(pyrrhotite, pyrite, chalcopyrite and sphalerite). The Hadong Fe-Ti-bearing ore bodies show a paragenetic sequence of magnetite-ilmenite ${\rightarrow}$ magnetite-ilmenite-pyrrhotite ${\rightarrow}$ ilmenite-pyrrhotite-rutile-titanite(and/or pyrite) ${\rightarrow}$ sulfides. Equilibrium thermodynamic interpretation of the mineral paragenesis and assemblages indicate that early Fe-Ti-bearing ore mineralization in the ore bodies occurs at about $700^{\circ}C$ which corresponds to oxygen fugacity of about $10^{-11.8}{\sim}10^{-17.2}$ atm with the decrease tendency of sulfur fugacity to about $10^0$ atm as equilibrium of $Fe_3O_4-FeS$. The change of ore mineral assemblages from Fe-Ti-bearing minerals to sulfides in late ore mineralization of the ore bodies indicates that oxygen fugacity would have slightly decreased to ${\geq}10^{-20.2}$ atm and increased sulfur fugacity to ${\geq}10^0$ atm.

• Economic and Environmental Geology
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• v.50 no.5
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• pp.375-387
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• 2017

Amphibolite-hosted Fe-Ti mineralization at the Soyeonpyeong Island, located in central western part of the Korean Peninsula is a typical orthomagmatic Fe-Ti oxide deposit in South Korea. The amphibolite intruded into NW-SE trending Precambrian metasedimentary rocks. Lower amphibolite is characterized by igneous layering, consisting of feldspar-dominant and amphibole-Fe-Ti oxide-dominant layers. The igneous layering shows complicated and/or sharp contact. In contrast, upper amphibolite has a more complicated lithofacies (garnet-bearing, coarser, and schistose), and massive Fe-Ti oxide ore alternates with schistose amphibolite. NS- and EW-trending fault systems lead to redistribute upper amphibolite-hosted Fe-Ti orebody and igneous layering of lower amphibolite, respectively. The whole-rock compositions of amphibolite and Fe-Ti oxide ore reflect their constituent minerals. Amphibolite shows significantly positive Eu anomalies whereas Fe-Ti oxide ore has weak negative Eu anomalies. Plagioclase (Andesine to oligoclase) and Fe-Ti oxide minerals have constant composition regardless of their distribution. Amphibole has a compositionally variable but it doesn't reflect the chemical evolution. Mineral compositions within individual layers and successive layers are relatively constant not showing any stratigraphic evolution. This suggests that there are no successive injections of Fe-rich magma or assimilation with Fe-rich country rocks. Contrasting Eu anomalies between amphibolite and Fe-Ti oxide ore also suggest that extensive plagioclase fractionation during early crystallization stage cause increase in $Fe_2O_3/FeO$ ratio and overall Fe contents in the residual magma. Thus, Fe-rich residual liquids may migrate at the upper amphibolite by filter pressing mechanism and then produce sheeted massive Fe-Ti mineralization during late fractional crystallization.

• Resources Recycling
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• v.27 no.3
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• pp.30-38
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• 2018

In this study, the behaviors of Fe selective chlorination in ilmenite ore by using PVC or $CO-Cl_2$ gas mixture as reducing agents under the condition of 1173 K, for 60 minutes were investigated. The weight loss ratio was 28% when PVC was applied as the reducing agent. The condensate formed at the outlet of reaction tube was identified as $FeCl_2$ by X-ray diffraction analysis. From these results, it was observed that iron in ilmenite ore reacted with HCl gas and Fe was selectively removed in the form $FeCl_2$. However, when $CO-Cl_2$ gas mixture was used as a reducing agent, the weight reduction ratio was 54%, and the condensate formed at the outlet of reaction tube after the experiment was estimated to be $FeCl_3$. It was observed that the ilmenite ore reacted with the $CO-Cl_2$ gas mixture and was simultaneously removed in the form of $FeCl_3$ and $TiCl_4$. However, the results of X-ray diffraction of ilmenite ore after the reaction showed that Fe was almost removed.

• Economic and Environmental Geology
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• v.27 no.6
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• pp.523-535
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• 1994

The strata-bound type iron ore bodies in the Chungju mine are interbedded with metamorphic rocks which are intruded by Mesozoic granitic rocks. The iron ore deposit occurs as layer or lens shape which are concordant with the metamorphic rocks. The iron ore is classified into banded and massive types based on the mode of texture and occurrence. Grain size and iron-oxides tend to become coarser toward massive ore than banded ore. Banded ores commonly contain internal layers defined by alternating magnetite- rich, hematite-rich, magnetite-hematite, and quartz-rich mesobands. The banded iron ore consists of hematite, magnetite, quartz, feldspar, and minor amounts of biotite, muscovite, chlorite, carbonates, epidote, allanite, and zircon. Massive ores which are characterized by high magnetite content occur in contact of granitic rocks. The massive iron ores consist mostly of magnetite and quartz, with minor amounts of hematite, pyrite, microcline, biotite, muscovite, chlorite, carbonates, epidote, allanite and zircon. Magnetite from banded and massive ores is almost pure $Fe_3O_4$ in composition, including 0.14 to 0.27 wt.% MnO and 0.10 to 0.15 wt.% MnO, respectively. Hematite of the ore contains 0.87 to 1.27 wt.% $TiO_2$ in banded ore and 3.44 to 6.96 wt.% $TiO_2$ in massive ore, respectively. Biotite shows a little compositional variation depending on ore types. Biotite of the banded ore has lower FeO, $TiO_2$ and $Al_2O_3$, and higher MgO and $SiO_2$ than the massive ore. The modes of occurrence and petrography of ore implies that massive ores might have been formed either under more reducing environments or higher temperature condition than banded ore. Banded ores might represent early episode of iron enrichment due to regional metamorphism. Massive ores might be related to the contact metamorphism resulting from late granitic intrusion.

• The Journal of the Petrological Society of Korea
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• v.19 no.1
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• pp.31-49
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• 2010

Nearly NS-trending Fe-Ti ore bodies intermittently occur in the Hadong anorthosites, south Korea, irrespective of the rock types of the anorthosites. In order to determine their occurrence mode and deformation history, we collected the features of occurrence and geological structures in the field, petrographic features using thin sections of the principal constituent rocks, and geochemical data of ilmenites in the ore body using electron probe microanalysis. Fe-Ti ore bodies examined in this study are divided into two types: dike- and lamina-types. It is steadily supported that the dike-type has intruded into the anorthositic rocks after their emplacement and solidification. And the laminar-type is probably a result of the mylonitization and transposition of the dike-type ore bodies parallel to the shear planes, due to later strong dextral ductile shearing. In the meantime, the Fe-Ti ore bodies have experienced the stronger dextral shearing in the more northern part of the study area, i.e. Cheongryong-ri, Wolhoeng-ri, Jonghwa-ri, and Jayangri and Baekun-ri in ascending order of its strength, together with the less content of $TiO_2$. All ilmenites of the ore bodies have very similar chemical composition, as pure ilmenite of 52~55 wt.% in $TiO_2$ content, irrespective of the occurrence mode and degree of later ductile shearing of the ore bodies. And they didn't experience to exsolve into magnetite. The structural data indicate that the Hadong anorthosites have deformed by NNE-trending folding, intrusion of the Fe-Ti ore bodies, NNW~NNE-trending dextral ductile shearing, NW~NNW-trending sinistral semi-brittle shearing, and intrusion of NNE~NE-trending mafic dykes in descending order of chronology after the formation of foliation of the anorthositic rocks. The foliation is interpreted as a result of the accumulation of crystals that settle out from the magma by the action of gravity.

• The Journal of the Petrological Society of Korea
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• v.22 no.2
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• pp.209-217
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• 2013

Fe-Ti ore bodies occur in the western part of the Sancheong anorthosites around Banggok-ri, Sancheong, Korea. Within ore bodies, a several centimetric size of anorthositic breccia are enclaved by ore-bearing mafic part and deformed strongly as a sigmoidal form by ductile shearing. The ore bodies have a general N-S trending foliations with westward dipping directions. The foliation developed in the ore bodies cut the foliation in anorthosites. The stretching lineations are well developed in the foliated plane of the ore bodies, showing ENE-trending with gentle plunging angle to the ESE direction. The sigmoidal patterns of anorthositic breccia in the ore bodies indicates the top-to-the-eastnortheastward shearing. Thus, in this study area the relationship between the geometric pattern and the ductile deformation is an important fact to understand the Sancheong Fe-Ti mineralized zone, Korea.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.247-256
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• 1996

Mineral commodities of metallic ore deposits related to Cretaceous granitoids in the Taebaegsan basin are distinguishable by rock types, diffferenciation index (D.I.) and chemical compositions. Deposits of Fe-Cu are related to granodiorite-quartz monzonite, those of Pb-Zn and W-Mo to granite-granodiorite and granite respectively. The ranges of D.I. of the granitoids are 39~71 for Fe-Cu deposits, 68~81 for Pb-Zn deposits, 78~89 for W-Mo deposits and 91~94 for Mn deposits. Major oxides of $K_2O$, CaO, MgO, FeO and $TiO_2$ and some trace elements and Rb/K, Sr/Ca and Cu/Fe also show distinguishable differences among the Cretaceous granitoids related to various mineral commodities of the ore depsits.

• Journal of Conservation Science
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• v.3 no.1 s.3
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• pp.13-18
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• 1994

Chemical analysis and metallographic observations of the iron slag were carried out in an attempt to estimate the old iron-making process. The slag containing $9.3\%\;TiO_2$ without Cu indicates that the ore used for smelting was sand iron, not rock ore. The phases identified in the slag were $ulv\ddot{o}spinel$, magnetite, $w\ddot{u}stite$, fayalite etc. This also supports the fact that the smelted ore was iron sand. The total amount of Fe and slag-making components$(=SiO_2+Al_2O_3+MgO+CaO)$ were $40.7\%\;and\;36.1\%$, respectively. These values were average ones found in the old slags formed in the ancient iron-making process. Assuming that $TiO_2$ in the ore combines with FeO, resulting in the formation of $ulv\ddot{o}spinel$, the estimated temperature of smelting was found to be about $1200^{\circ}C$.

• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.372-384
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• 1991

The sulfation of the domestic titaniferous magnetite ore with ammonium sulfate was investigated to find a cyclic process for the production of synthetic rutile and high purity iron oxide and to test the feasibility of ammonium sulfate being an alternative sulfation agent. The proper sulfation conditions were determined to be a temperature of $425^{\circ}C$, 2.5 hours of reaction time, the weight ratio of ammonium sulfate to titaniferous magnetite : 11, and particle size or titaniferous magnetite : -250 mesh. 90.4 % of $TiO_2$ and 85.3 % of iron were extracted from the titaniferous magnetite sulfated under these conditions by the water leaching. From the leachate $TiO_2$ of 93.8 % purity as a mixture of rutile and anatase and ${\alpha}-Fe_2O_3$ of 97.6 % purity were obtained.