• 한국재료학회지
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• 제16권8호
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• pp.497-502
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• 2006

Recently, many attention have been focused on illite as a material for the well-being industry. Illite contains various kinds of iron bearing materials and they restrict their usage. In this study, Fe impurities in the illite produced in Yeongdong-gun, Chungcheongbuk-do were characterized and their removal experiments were performed. According to the characterization of illite raw ore, it contained 1.54 wt.%$Fe_2O_3$ due to the existence of iron oxide($Fe_2O_3$) and pyrite($FeS_2$). The raw ore was crushed into 3 mm or less using cone crusher and then ground by rod mill for the liberation of impurity mineral. For the removal of iron bearing minerals, an acid treatment, a flotation, a magnetic separation, and a flotation combined with magnetic separator were performed respectively. When the illite raw ore was treated with magnetic separation and various kinds of acid, 1.54wt.%. $Fe_2O_3$ content was reduced to 0.78 and 1.0 wt.%, respectively. On the other hand $Fe_2O_3$ content was reduced to be 0.52 wt.% after flotation. These results indicate that iron bearing minerals cannot be reduced below 0.3wt.%$Fe_2O_3$. However, combination of magnetic separation and flotation enable us to get 0.24wt.% of illite concentrate. It is concluded that, for the refinement of illite from Yeongdong-gun, the flotation combined with magnetic separation is good for high purity illite.

• 한국지구과학회지
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• 제23권1호
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• pp.97-104
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• 2002

Mulgeum, Yangseong, Maeri and Kimhae iron ore deposits in Gyeongnam Province are hydrothermal skarn type magnetite ore deposits in propylitized andesitic rock near the contact with Cretaceous Masanite. Symmetrical zoned skarns are commonly developed around the magnetite veins. The skarn zones away from the vein are quartz-garnet skarn, epidote skarn and epidote-orthoclase skarn. Oxygen isotope analyses of coexisting minerals from andesitic rock, Masanite and major skarn zones, and of magnetite, hematite and quartz were conducted to provide the information on the formation temperature, the origin and the evolution of the hydrothermal solution forming the iron ore deposits. Becoming more distant from the ore vein, temperatures of skarn zones represent the decreasing tendency, but most ${\delta}^{18}O$ and ${\delta}^{18}O_{H2O}$ values of skarn minerals represent no variation trend, and also the values are relatively low. Judging from all the isotopic data from the ore deposits, the major source of hydrothermal solution altering the skarn zones and precipitating the ore bodies was magmatic water derived from the deep seated Masanite. This high temperature hydrothermal solution rising through the fissures of propylitized andesitic rock was mixed with some meteoric water, and occurred the extensive isotopic exchange with the propylitized andesitic rock, and formed the skarns. During these processes, the temperature and ${\delta}^{18}O_{H2O}$ value of hydrothermal solution were lowered gradually. At the main stage of iron ore precipitation, because all the alteration was already finished, the new rising hydrothermal solution formed only the magnetite ore without oxygen isotopic exchange with the wall rock.

• 자원환경지질
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• 제25권1호
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• pp.17-25
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• 1992

South ore deposits of the Dunjeon gold mine is a fissure-filling vein emplaced in the Cretaceous granodiorite, skarnized and/or hornfelsified Ordovician Dumudong Formation. Mineralization can be divided into three distinct depositional stages on the basis of vein structure and mineral assemblages. Sb, Bi sulfosalts minerals, such as tetrahedrite, bournonite, boulangerite, cosalite, lillianite, heyrovskyite, unknown Pb-Bi-Sb-S mineral, native Sb, native Bi and Au-Ag minerals are mainly deposited in stage II. The formation temperature and sulfur fugacties of Sb, Bi minerals in the stage II deduced from thermodynamic considerations are from $172^{\circ}$ to $378^{\circ}C$ and $10^{-10.6}$ to $10^{-19.4}$ atm. Those temperatures are good agreement with temperature data obtained by fluid inclusion study which has reported already.

• 자원환경지질
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• 제32권3호
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• pp.237-245
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• 1999

The Mujeong au-Ag hydrothermal vein type deposits occur within the Teriary igneous rocks of the Janggi basin. Ore minerals consist of pyrite, pyrrhotite, sphalertite, chalcopyrite, galena, cosalite, lillianite, argentite and electrum, and associated with epidotization, sericitization and pyritization. Fluid inclusion studies reveal that ore fluids were low saline with a simple NaCl-$H_{2}O$ system. Fluid inclusion data indicate that homogenization temperatures and salinities of fluid are 150 to $340^{\circ}C$ and 1.0 to 6.5wt.% NaCl equivalent, respectively. Sulfur isotope compositions of sulfied minerals ( ${\delta}^{34}S$=6.2 to 9.6$\textperthousand$) indicate that the ${\delta}^{34}S_{H2S}$ value of ore fluids was about 10.4$\textperthousand$. This ${\delta}^{34}S_{H2S}$ value is likely consistent with and hydrothermal sulfur, whereas the fluids were highly influenced by mixing with meteoric water. Measured and calculated oxygen and hydrogen isotope values (${\delta}^{18}O_{H2O}$=-2.7 to 3.4 $\textperthousand$, ${\delta}D_{H2O}$ = -83.6 to -52.7 $\textperthousand$) of ore forming fluids suggest mixing with hydrothermal and meteoric water. Equilibrium thermodynamic interpretation by mineral assemblages and chemistry indicates that sulfur fugacities (-log $fs_2$) ore forming fluids range from 9.0 to 12.6 atm stage II.

• 자원환경지질
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• 제25권4호
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• pp.379-395
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• 1992

The gold ore deposits of Nakcheon, Gongyeong and Dongmyeong mine in the Imgye district are E-W trending fissure filling veins emplaced in Precambrian Jungbongsan granite and sedimentary rocks of Cambrian Yangdeog group. The K-Ar age for vein alteration sericite and vein laced muscovite are 73 and 93 Ma, respectively. Vein structure and mineralogy indicate the three distinct depositional stages: I) basemetal sulfides and tin minerals, II) gold-basemeatl sulfides, III) gold-silver-basemetal sulfides. Major gold and silver ore minerals are electrum, native silver, pyrargyrite and argentite. Fluid inclusion data indicate that filling temperatures were from $350^{\circ}C$ to $190^{\circ}C$ through stage I, II and III. Salinities were in the range of 0.0~9.5 NaCl eq.wt.% and do not reveal any systematic trend. Intermittent boiling of ore fluid during stage I is indicated by fluid inclusions in quartz. Fluid pressure during stage I which is estimated from fluid inclusions showing boiling evidence range from 50 to 100 bars. Gold ore deposits of the Imgye district were formed under higher temperatures and lower sulfur fugacities compared with the Eunchi silver ore deposits about 8 Km apart from the Imgye district.

• 자원환경지질
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• 제15권4호
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• pp.221-233
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• 1982

Ssangjeon tungsten ore deposits is a complex pegmatite deposits embedded along the contact between pre-Cambrian Buncheon granite gneiss and amphibolite. This pegmatite vein developed 2 km along the strike and thickness varies from 10m to 40m. Mineral constituent of the normal pegmatite are quartz, microcline, plagioclase, muscovite, biotite, tourmaline and garnet. The vein paragenesis is complicated by repeated deposition of quartz but three distinct depositional stage can be recognized. Quartz A stage is the stage of the earliest milky white quartz deposition as a rock forming mineral of normal pegmatite. Quartz B stage is the stage of gray to dark gray quartz replace earlier formed normal pegmatite minerals. Quartz C stage is the stage of latest white translucent massive quartz replace quartz A and B. Tungsten ore minerals and other sulfide minerals were precipitated during quartz B stage. Ore minerals are ferberite and scheelite. Minor amount of molybdenite, arsenopyrite, pyrrhotite, pyrite, chalcopyrite, sphalerite, galena, pentlandite, bismuthinite, native bismuth and marcasite accompanied. Fluid inclusion in quartz A and B are gaseous inclusions and liquid inclusions are contained in quartz C as a primary inclusions. Salinity of inclusions in quartz A and B ranges from 4.5 to 9.5 wt. % and from 5.1 to 6.0 wt. % equivalent NaCl respectively. Homogenization temperature of quartz A; quartz B and quartz C ranges from 415 to $465^{\circ}C$, from 397 to $441^{\circ}C$ and from 278 to $357^{\circ}C$. $CO_2$ content of the ore fluid increased at the ends of quartz B stage.

• 자원환경지질
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• 제24권2호
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• pp.107-129
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• 1991

The Yonghwa gold-silver deposits are emplaced along $N15^{\circ}{\sim}25^{\circ}W$ trending fissures in middle Cretaceous porphyritic granite or Precambrian Sobaegsan gneiss complex. The results of paragenetic studies suggest that vein filling can be subdivided into four identifiable stages; state I: the main sulfide stage, characterized by base-metal sulfide minerals, iron oxides and minor electrum, stage II: electrum stage, stage III: electrum and silver-bearing sulfosalts stage, stage IV: post ore stage of carbonates and quartz. The ore mineralogy suggests that depositional temperature of the formation of the gold and silver minerals are estimated as 200 to $250^{\circ}C$ and 140 to $180^{\circ}C$, respectively. Sulfur fugacity of the formation of the gold and silver minerals are estimated as $10^{-14.0}$ to $10^{-12.2}$ atm and $10^{-18.5}$ to $10^{-17.2}$ atm, respectively. A consideration of the pressure regime during ore deposition bases on the fluid inclusion evidence of boiling suggests lithostatic pressure of less than 180 bars. This range of pressure indicate that vein system lay at depth of 700m below the surface at the time during mineralization. Salinities of ore-bearing fluids range from 0.4 to 6.9 wt.% equivalent NaCl. The sulfur and carbon isotopic data reveal that these elements were probably derived from a deep-seated source. The ${\delta}^{18}O$ of the hydrothermal fluid was determined from ${\delta}^{18}O$ values of quartz and calcite. Oxygen and hydrogen isotopic studies reveal that meteoric water dominate over ore-bearing fluid.

• 자원환경지질
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• 제20권2호
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• pp.97-106
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• 1987

The geology of the Bupyeong mine area is consisted of Precambrian Gyeonggi gneiss complex and Mesozoic igneous rocks; i.e., pyroclastic rocks, intrusive breccia, granite and felsic porphyries which were formed during a Jurassic to early Cretaceous resurgent caldera evolution. Granites are not observed on the surface and in the underground of the mine. Bupyeong silver deposits occur as stockworks of base metal sulfides- minor silver minerals-quartz - carbonate veinlets, hosted by pyroclastic rocks and intrusive breccia at the southwestern margin of the caldera. Silver occurs mainly as native silver, and other silver minerals, minor in quantity, are argentite, tetrahedrite-freibergite, pyrargyrite, polybasite, canfieldite and dyscrasite. The average grade of silver ore is about 180g/t Ag. Discrimination of silver ore from the country rocks depends largely on the chemical analyses of rock samples taken every two meters from tunnels, diamond-drilling cores and mining stopes, because silver minerals are hardly observed in the ore by crude eye, and silver orebodies do not properly coincide with the concentrated zone of base metal sulfides which were precipitated at the earlier stage than the stage of precipitation of native silver. General characteristics of the loci of the silver orebodies are as follows; (1) The host rocks of orebodies are pyroclastic rocks and intrusive breccia. (2) Many of the orebodies are distributed around Gyeonggi gneiss complex. Especially where the paleotopography of gneiss complex shows a gradual slope, the basal stratigraphic horizon of the pyroclastic rocks unconformably overlying the gneiss complex offered a favorable loci of high grade ore. (3) $N5^{\circ}W$ to $N15^{\circ}$ E-striking faults played an important role in the localization of the orebodies. (4) Conduits of intrusive breccia within the gneiss complex, through which the intrusive breccia intruded into the upper pyroclastic rocks, exist beneath most of the main orebodies. This suggests that the conduits of intrusive breccia served as channelways for the migration of ore fluids.

• 자원환경지질
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• 제23권1호
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• pp.1-9
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• 1990

A couple of Au-Ag-bearing epithermal quartz veins of Cretaceous(87.9Ma) in age are developed in the Cretaceous(112Ma) granodiorite batholith which was emplaced in Mesozoic Baegyari sedimentary formation. Au minerals consist mostly of electrum with a 54.2-61.9 wt% Au and are closely associated with sulfide minerals including pyrite, chalcopyrite, pyrrhotite, galena and sphalerite. Homogenization temperatures of fluid inclusions in quartz, fluorite and calcite are $196-368^{\circ}C$ (avg. $240^{\circ}C$), $74-176^{\circ}C$ (avg. $115^{\circ}C$) and $75-200^{\circ}C$ (avg. $119^{\circ}C$) respectively. Sulfur isotopic compositions( +5- +8‰) of ore sulfides indicate a deep-seated sulfur origin. Oxygen isotope compositions of different stages of quartz vary from +5.6 to +9.3‰ and calculated ${\delta}^{18}O$ values of ore fluid at $250^{\circ}C$ range from -3.2 to +0.4‰, reflecting an isotopically evolved ore fluid mixed with a $^{18}O$ depleted meteoric water under the variable mixing ratios between hydrothermal and meteoric waters. Isotopic data of calcite minerals support the above conclusions.

• 자원환경지질
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• 제25권3호
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• pp.297-316
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• 1992

The Daebong gold-silver deposits is located in 8 km southwest of Cheongyang, Chungcheongnam-Do, Republic of Korea. The gold-silver-bearing hydrothermal quartz veins was formed within the Precambrian metasediments of Gyeonggi massif. Ore minerals occur as mainly of pyrite, sphalerite (0.78~6.19 wt.% Cd), galena, pyrrhotite and minor amounts of chalcopyrite, arsenopyrite, magnetite, ilmenite, chalcocite, electrum (55.00~89.55 wt.% Au) and argentite. The gangue minerals are quartz, calcite, chlorite, K-feldspar, biotite. Wall-rock alterations such as chloritization, silicification, pyritization, carbonatization and sericitization can be observed near the quartz veins. According to the mineral paragenetic sequence based on vein structure and mineral assemblages, three stage mineralizations can be recognized. Fluid inclusion, sulfur isotope and thermodynamic data show that the ore minerals were dominantly deposited at the between 388 and $204^{\circ}C$ from fluids with salinities of 8.1~0.3 wt.% equivalent NaCl, and sulfur isotope value 4.84 to 6.40 per mil of sulfides indicates igneous sources of sulfur in the hydrothermal system and fluid inclusion salinity data suggest that thermal fluids may have magmatic origin with some degree mixing of meteoric water.