• Economic and Environmental Geology
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• v.21 no.3
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• pp.269-276
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• 1988

Ore deposits of Dadeok mine, the largest in the Bonghwa gold mining district, are composed of numerous gold and silver-bearing quartz veins emplaced in granite batholith. Mineralization of the Pungjeong vein, one of the representative vein in the mine was investigated. K-Ar age of sericite in the vein is $84{\pm}5$ Ma. Hypogene 6pen-space filling can be devided into four paragenetic stages; (1) fine grained quartz and carbonate; (2) quartz and carbonates with base metal sulfides, electrum, native silver, argentite, polybasite, freibergite, pyrargyrite, and Cu-Ag-Fe-S minerals; (3) quartz with base metal sulfides; (4) quartz and calcite with or without pyrite. Composition of electrum ranges from 44.17 to 56.50 atomic % Ag. Meanwhile FeS content of sphalerite coexisting with elctrum in stage II range from 0.01 to 1.67 mol. %. Homogenization temperatures for quartz and sphalerite of stage II ($239^{\circ}$ to $310^{\circ}C$), quartz of stage III ($206^{\circ}$ to $255^{\circ}C$) and quartz and calcite of stage IV ($232^{\circ}$ to $253^{\circ}C$) show little time-space variation during mineralization. Salinities of the fluid inclusions range from 5.5 to 12.8wt% NaCI in stage II, 7.3 to 12.3wt% in stage III and 4.5 to 8.0wt% in stage IV. Based on the homogenization temperatures, Fe content of sphalerite and Ag content of electrum, tempera ture and sulfur fugacity for stage II are estimated to be $208^{\circ}$ to $310^{\circ}C$ and $10^{-9.2}-10^{-12.8}$ bars, respectively.

• Journal of the Korean institute of surface engineering
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• v.37 no.5
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• pp.253-262
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• 2004

Calcareous deposits are the consequence of pH increase of the electrolyte adjacent to metal surface affected by cathodic current in seawater. It obviously has several advantages over conventional coatings, since the calcareous deposit coating is formed from coating (Mg$^{2+}$, $Ca^{2+}$) naturally existing in seawater. In consideration of this respect, environment friendly calcareous deposit films were formed by an electro deposition technique on steel substrates submerged in 48$^{\circ}C$ natural seawater. And the influence of current density, coating time and attachment of steel mesh on composition ratio, structure and morphology of the electrodeposited films were investigated by Scanning Electron Microscopy(SEM), Energy Dispersive Spectroscopy(EDS) and X-Ray Diffractor(XRD), respectively. Accordingly, this study provides a better understanding of the composition between the growth of $Mg(OH)_2$ and $CaCO_3$ during the formation of electro deposit films on steel substrate under cathodically electrodeposition in $48^{\circ}C$ natural seawater. The Mg compositions, in general, are getting decreased regardless of current density but Ca compositions are getting increased as electrodeposition time runs. That is, $Mg(OH)_2$ compounds of brucite structure shaped as flat type is formed at the initial stage of electrodeposition, but CaCO$_3$ compounds of aragonite structure shaped as flower type is formed in large scale. Besides, $Mg(OH)_2$ compounds were much formed at 5 A/$\m^2$ environment condition compared to the 3 A/$\m^2$ and 4 A/$\m^2$ environment conditions. This is because that OH- which was comparatively largely generated at the metal surface is preferably combined with $Mg^{2+}$TEX>.

• Journal of the Korean Professional Engineers Association
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• v.38 no.6
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• pp.1-9
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• 2005

The Republic of Korea (South) and the Peaples Republic of Korea (North) had agreed to exploit the North Korean rich natural resources starting from the year of 2006. Through this mutual agreement DPRK shall quarantee ROK's investment in the North Korean Mines and supply mineral products for the compasation of the financial investment supported by ROK. In the area of northern part of Korea, many kind of natural resources such as Magnesite, Iron, Gold & Silver, Copper, Lead & Zinc, and Coal are plentifully deposited. In the area of southern part of Korea, however, most kind of natural resources have been exhausted and so presently major minerals such as Gold & Silver, Copper, Lead & Zinc and Coal are being imported and relying on foreign countries in whole quantity of the requirement. On the other hand Northern Part of Korea is making very slow progress in mining and exploitation owing to the lack of investment even though there are rich deposits of natural resources. And in Southern Part of Korea, they have most advanced production facilities and technologies in the world in the fields of Mineral Floatation, Steel Manufacturing, Nonferrous Metal Smelting & Refining and those plants fabrications. A combination of Southern Technologies together with Financial Support and Northern rich natural resources & Labour Power will be a most hopeful, desirable and mutually required 'South-North economic Cooperation' as the mining industries are labour intensive.

• Journal of Korean Society on Water Environment
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• v.32 no.1
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• pp.80-88
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• 2016

The main purpose of this study was to derive managerial priority for pollutants in drinking water using the Delphi technique and analytic hierarchy process (AHP) method. We collected fundamental existing items based on a literature review for water pollutants, and deduced a total of 36 sub-items from nine core sectors, as follows: organic matter; inorganic substances; pathogenic organisms; chemicals; heavy metals; radioactive substances; sediment deposits; heat; and oil, and then conducted the first round of an expert study to ensure that objective indicators properly evaluate major issues for management of for drinking water quality. In the following round, the necessity and importance assessments of adjusted items were implemented using a content validity ratio index. Finally, items modified by Delphi surveys were applied to AHP. We computed weighted values by pair-wise comparison of sub-items and each of five sectors modified by the second round. According to the results of AHP, the managerial priority for pollutants in drinking water was as follows; while heavy metal placed first in importance, pathogenic organisms came second, followed by inorganic substances, organic matter and chemical substances from the sector perspective.

• Korean Journal of Materials Research
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• v.27 no.12
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• pp.672-678
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• 2017

In the production of zirconium cladding tube, a pickling acid solution is used to remove surface contaminants, which generates tons of pickling acid waste. The waste pickling solution is a valuable resource of Hf-free Zr. Many studies have investigated separating the Hf-free Zr source from the waste pickling acid. The results showed that $Ba_2ZrF_8$ precipitates prepared from the waste pickling acid were useful as an electrolyte for the electrorefining of Zr in molten salt. In the present work, electrorefining was performed in a $Ba_2ZrF_8-LiF$ binary electrolyte to recover Zr from a Hf-free CuZr ingot anode prepared by electroreduction. Before electrorefining, two pretreatments are performed. First, electrolyte melting was carried out to determine the eutectic temperature, and second, the electrolyte was treated to eliminate impurities, mainly hydride. After electrorefining, the cathode deposits were analyzed by $O_2$ gas analyzer and SEM-EDX to explore the possibility of recovering nuclear-grade Zr metal. Moreover, the anode was analyzed by SEM-EDX to determine the Zr dissolution depth.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.55-59
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• 2004

We fabricates the $TiO_2$ thin film from anatase phase $TiO_2$ powder having good photocatalytic property using aerosol deposition method at room temperature. Aerosol deposition method, which sprays an aerosol powder with ultrasonic velocity and deposits a thin film on substrate at low temperature, has the advantages of low thermal stress and low cost. To fabricate the $TiO_2$ thin film, the aerosol bath pressure and chamber pressure were 500 torr and 0.4 torr, respectively. The difference of aerosol bath pressure and chamber pressure accelerated the $TiO_2$ nano powder to ultrasonic velocity through the nozzle of $0.4 mm{\times}10 mm$ and $TiO_2$ thin film was finally formed. SS mesh with diameter of 50 mm was used as a substrate to apply the $TiO_2$ thin film to water quality purification. The raw powder was dehydrated for the good dispersion of $TiO_2$ powder. To suppress the formation of second particle, the powder was dispersed for 90 min in alcohol bath by ultrasonic treatment and desiccated. The grain size of $1 {\mu}m$ was observed in $TiO_2$ thin film deposited on SUS mesh by scanning electron microscopy (SEM). The anatase phase of $TiO_2$ thin film was also observed by X-ray diffraction (XRD) and the anatase phase of raw powder was nicely maintained after aerosol deposition. The results are applicable to water treatment filter having photocatalytic reaction.

• Journal of the Korean institute of surface engineering
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• v.47 no.1
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• pp.39-47
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• 2014

The peculiar feature of cathodic protection in seawater has the capability to form mineral calcareous deposits such as magnesium and calcium on metal surfaces. It is assumed that $OH^-$ ions are generated close to the metal surface as a result of cathodic protection and generated $OH^-$ ions increases the pH of the metal/seawater interface outlined as the following formulae. (1) $O_2+2H_2O+4e{\rightarrow}4OH^-$, or (2) $2H_2O+2e{\rightarrow}H_2+2OH^-$. And high pH causes precipitation of $Mg(OH)_2$ and $CaCO_3$ in accordance with the following formulae. (1) $Mg^{2+}+2OH^-{\rightarrow}Mg(OH)_2$, (2) $Ca^{2+}+CO{_3}^{2-}{\rightarrow}CaCO_3$. The focus of this study was to increase the amount of $CO{_3}^{2-}$ with the injection of $CO_2$ gas to the solution for accelerating process of the following formulae. (1) $H_2O+CO_2{\rightarrow}H_2CO_3$, (2) $HCO^{3-}{\rightarrow}{H^+}+CO{_3}^{2-}$. Electrodeposit films were formed by an electro-deposition technique on steel substrates in solutions of both natural seawater and natural seawater dissolved $CO_2$ gas with different current densities, over different time periods. The contents of films were investigated by scanning electron microscopy(SEM) and X-ray diffraction(XRD). The adhesion and corrosion resistance of the coating films were evaluated by anodic polarization. From an experimental result, only $CaCO_3$ were found in solution where injected $CO_2$ gas regardless of current density. In case of injecting the $CO_2$ gas, weight gain of electrodeposits films hugely increased and it had appropriate physical properties.

• Economic and Environmental Geology
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• v.23 no.2
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• pp.245-259
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• 1990

Petrochemical analyses of granitic rocks including trace element, REE and oxygen isotope were carried out to understand petrogenesis of plutonic rocks from the Chungju, Wolaksan and Jecheon granite batholiths, which might be related with tungsten-base metal-fluorite mineralization in the Hwanggangri metallogenic province. Different geochemical characteristics such as major and trace elements were found between Jurassic Daebo granitic rocks (Chungju, Jecheon, Wonju, and Boeun granitic rocks) and Cretaceous Bulgugsa granitic rocks (Wolaksan, Muamsa and Sokrisan granitic rocks). Cretaceous granitoids are characterized by high $SiO_2$and $K_2O$ contents and low $TiO_2$, $Al_2O_3$, MgO and CaO contents. They also have relatively high contents of trace elements(Zn, V, Co, Cr, Sr, and Ba) in comparison with the Jurassic granitoids. (Eu)/($Eu^*$) and $(La/Lu)_{CN}$ ratios of Jurassic plutons vary from 0.78 to 1.13 and from 26.02 to 30.5, respectively, while the ratios of Cretaceous ones range from 0.22 to 0.28 and from 4.42 to 14.2, respectively. The REE patterns of the Cretaceous and Jurassic granitic rocks have quite different Eu anomalies: large negative Eu anomaly in the former, and mild or absent Eu anomaly in the latter. The large Eu negative of Cretaceous granitic rocks are interpreted as a differentiated product of fractional crystallization of granitic magma deduced by Rayleigh fractionation model(Tsusue et al., 1987). Oxygen isotopic compositions of quartz for Daebo and Bulgugsa granitic rocks range from 9.98 to 10.51‰ and from 8.26 to 9.56‰, respectively. The Daebo granitic rocks enriched in $^{18}0$ suggest that the magma be undergone different partial melting processes from the Bulgugsa ones. Of the Bulgugsa granitoids, Wolaksan and Sokrisan mass have different contents of trace elements and ${\delta}\;^{18}0$ values of the silicate minerals, which indicate that they are not from the identical source of magma. Many mineral deposits are distributed in and/or near the Wolaksan and Muamsa granitic rocks, but a few mineral deposits are found in and near the Chungju and Jecheon granite batholiths. It might be depend on geochemisty of the related igneous rocks which have low contents of Ba, Sr, Co, V, Cr, Ni, Zn and high contents of Nb and Y, and on lithology of country rocks such as cabonate and noncarbonate rocks.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.157-166
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• 2001

Numerous base-metal bearing hydrothermal quartz vein deposits occur in the Hunan province of southern China. The Tangguanpu lead-zinc-tin-silver mine is the major producer among these deposits. Lead-zinc-tin-silver mineralization occurs in a single stage of massive quartz veins which filled fractures in fault zones within Paleozoic metasedimentary rocks. Sphalerite, chalcopyrite, galena, pyrite, arsenopyrite and pyrrhotite are the principal sulphide minerals in the Tangguanpu lead-zinc ores with minor amounts of tin- and antimony-bearing sulphides (stannite, teallite, boulangerite and tetrahedrite). Based on the iron and zinc partitioning between coexisting stannite and sphalerite, the formation temperature for this mineral assemblage range from 300$^{\circ}$ to 330$^{\circ}$C, which relatively agree with the upper part of homogenization temperature of fluid inclusion in quartz (20T-358$^{\circ}$C). Fluid inclusion data show that main lead-zine-tin-silver mineralization occurred from $H_{2}O$-NaCl fluids with relatively low salinities (11.2-7.3 wl.% eg. NaCI) at temperatures between 207$^{\circ}$ and 358$^{\circ}$C. The relationship between homogenization temperature and salinity suggests a history of cooling and dilution followed by initial boiling. Evidence of initial fluid boiling may indicate the fluid trapping pressures of 180 bars. The ${\delta}^{34}S{{\Sigma}S}$ values of -5.0 to 1.1 %, indicate an igneous source of sulfur in the Tangguanpu lead-zinc-tin-silver hydrothermal fluids.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.2
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• pp.125-131
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• 2009

An electrolytic system (zinc anode-gallium cathode) was setup to evaluate the performance of several stirrers prepared for this study, where stirrers have been used to prevent uranium from forming dendrite on the cathode in pyrochemical process. In the case of no-stirring condition, zinc dendrites began to grow on the gallium surface in 1 hour and some dendrite grew out of the cathode crucible around 6 hours. When a rectangular stirrer or a tilt stirrer was rotated, at 40${\sim}$150 rpm, to mix the liquid gallium cathode, dendritic growth of zinc metal was prevented irrespective of revolution speed, but some of the deposits overflowed out of the cathode crucible owing to the large centrifugal forces at 150 rpm. The harrow stirrer did not nearly retard the dendrite growth at 40 rpm, but the dendrite growth was retarded at higher than 100 rpm and the zinc deposits also did not overflow at 150 rpm. Pounder could also prevent the dendrite growth to some extent but it had some difficulties in operation compared with other types of stirrers.