• Korean Journal of Materials Research
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• v.27 no.3
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• pp.166-171
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• 2017

Removal of phosphate from environmental water has become more important to prevent eutrophication. In the present study, sorption behavior of phosphate onto magnesite was investigated under different conditions. The optimum pH of phosphate adsorption was determined to be 6.0. The adsorption capacity was found to decrease with increasing temperature, which indicates that a low temperature was beneficial for phosphate adsorption. The sorption capacity for phosphate was found to be 10.2 mg/g at an initial concentration of 100 mg/L and a dose of 2 g/L. The first order kinetic equation and Freundlich isotherm model fit the data well. Phosphate adsorption on magnesite was explained by electrostatic attraction and weak physical interactions.

• Resources Recycling
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• v.14 no.1
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• pp.33-38
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• 2005

Worldwide magnesium market has been considerably growing recently due to adoption as light materials for automobile engines and electronic devices such as mobile phones. In this study, it is to prepare magnesium oxide, which is the first-step product in smelting of magnesium from the ore, using magnesite of Yongyanag mines in North Korea as raw ores. MgO grade of the magnesite was about 45 wt%, and SiO$_2$, CaO, Al$_2O_3$ and Fe$_2O_3$ were contained as impurities. The sample ore was crushed, classified and thermally analyzed to determine its calcination temperature. The sample of 45-75 ${\mu}m$ size was calcined at 600-900$^{\circ}C$, and effect of temperature on calcination and change of the particle shape was investigated. Optimum temperature of the calcination was about 750$^{\circ}C$, and 30 minutes was sufficient to obtain over 99% conversion. The purity of the calcined MgO was about 95 wt%.

• Resources Recycling
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• v.26 no.3
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• pp.69-78
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• 2017

Magnesium has been used as parts of vehicles, case materials of notebook PC and mobile phone, and its demand has been increasing recently. Its extraction technologies were classified according to the two major reduction methods: the fused salt electrolysis and the thermal reduction method. A research on the extraction of magnesium from magnesite which has been being carried out at KIGAM was briefly introduced here. Magnesium was prepared using a fused salt electrolysis method through preparation of anhydrous magnesium chloride with lab scale experiments.

• Resources Recycling
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• v.18 no.6
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• pp.38-45
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• 2009

Dissolution characteristics of magnesite ore in hydrochloric acid solution and removal of impurity were investigated. The dissolution yield increased with increasing temperature and with decreasing particle size. The optimum conditions for dissolution were found to be reaction period of 120 min, reaction temperature of $80^{\circ}C$ and mean particle size of 100. Under optimal dissolution condition the extraction of Mg was 98%. It was found that most of Si and Al exist in the residue, and they can be removed by filtering. Dissolved impurity ions were precipitated as metal hydroxides by pH adjustment. Polymers were used as coagulants for metal hydroxides and the suitable coagulant dosage was 1mg/100ml of non-ionic polymer.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.24-28
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• 2010

Since the reaction of mineral fixation proceeds with a very slow rate, the pretreatment method to increases the rate of carbonation reaction should be required. To increase the reactivity of serpentine with $CO_{2}$, two pretreatment methods are performed in this study. The heat treatment is done at $630^{\circ}C$. A heat-treated serpentine shows that the strength of -OH has a lower peak in FT-IR spectrum. Chemical pretreatment is the method of leaching of magnesium from serpentine using sulfuric acid at $75^{\circ}C$ for 1 h. Because the protonation of the oxygen atoms polarizes and weakens the Mg-O-Si bond, the removal of magnesium atoms from the crystal lattice was facilitated. After performing the pre-treatment of serpentine, $CO_{2}$ fixation experiments are performed with treated serpentine in the batch reactor. Heat-treated serpentine is converted into 43% magnesite conversion, whereas untreated serpentine has 27% of magnesite conversion. Although the results of the heat-pretreatment are encouraging, this method is prohibited due to excessive energy consumption. Furthermore chemical pretreatment serpentine routes have been proposed in an effort to avoid the cost prohibitive heat pretreatment, in which the carbonation reaction was conducted at 45 atm and $25^{\circ}C$. Chemical-treated serpentine, in particularly is corresponded to a conversion of 42% of magnesite compared to 24% for the un-treated serpentine.

• The Journal of the Petrological Society of Korea
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• v.11 no.2
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• pp.90-102
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• 2002

The studied Fe-REE ore consists of magnetite, ankerite, siderite, magnesite and strontianite as the major constituent, and monazite, columbite, fergusonite, apatite, aegirine-augite, Na-amphibole, pyrite, chalcopyrite, sphalerite, molybdenite and barite as accessaries. Wall rock of ore deposits is replaced to fenite due to Na-metasomatism and mainly consists of sugary albite and Na-amphibole. Monazite $Ce_{0.49}La_{0.31}Pr_{0.14}Nd_{0.03}Gd_{0.03})PO_4$ is the main mineral for REE deposit and shows myrmekitic intergrowth with strontianite $Ca_{0.02-0.16}Sr_{0.84-0.98}CO_3$ and is corroded by carbonate minerals. Mineral forming sequence can be divided into early and late periods by the development of microfractures. The early period minerals such as magnetite, ankerite, magnesite, monazite and apatite show well developed networks of microfractures due to cataclastic deformation caused by enriched $CO_2$ gas in melts during emplacement. The late minerals of columbite, fergusonite, siderite molybdenite, chalcopyrite and sphalerite formed after the brecciation event and have little micro-fractures. Ankerite, magnesite, monazite, strontianite, barite and pyrite seem to be formed continuously from the ealy to the late period since they show textures both with well developed fractures and also with little fractures. Mineral chemistry, mineral assemblages such as various carbonate minerals, magnetite, REE minerals of monazite and fergusonite, Sr mineral of strontianite, and Nb minerals of columbite, myrmekitic texture of monazite and ankerite, and well developed fenite along ore deposits observed from this studied area strongly indicate that this Hongcheon Fe-REE ore deposits are formed from carbonatitic melt and its rock type is late differentiated Fe-carbonatite or ankerite-carbonatite.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1230-1232
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• 2003

This study aims to extract maximum geological information using the ASTER (Advanced Spaceborne Thermal Emission and Reflection radiometer) images of a part of south India. The area chosen for this study is characterized by rock types such as Migmatite, Magnetite Quartzite, Charnockite, Granite, dykes, Granitoid gneiss and Ultramafic rocks, and minerals such as Bauxite, Magnesite, Iron ores, Calcite etc. Advantage was taken of the characteristic reflectance and absorption phenomenon in the VNIR, SWIR and TIR bands for these rocks and minerals, and they were mapped in detail. Image processing methods such as contrast stretching, PC analysis, band ratios and fusion were used in this study. The results of the processing matched with the field details and showed additional details, thus demonstrating the usefulness of ASTER (especially the SWIR bands) data for better geological mapping.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.291-300
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• 2013

The potential mineral resources in North Korea are magnesite, limestone, coal, graphite, iron, gold, silver, lead, and zinc. North Korea is mainly exporting coal and iron to China(70%) and EU countries. Gold ore reserves(or resources) in North Korea are about 2,000 tons and annual production is 2 tons based on metal. Major gold mines are Sooan, Holdong, and Daeyoodong mines and six smelters are operating. Fe ore reserves (or resources) are 4.3 billion tons and annual production is about 5 million tons based on 63.5% Fe. Major iron mines are Moosan, Leewon, Eunryul, Shinwon, and Jaeryong and 7 smelters are operating. Pb and Zn ore reserves(or resources) are Pb 470,000 tons and Zn 15 million tons, and annual productions are about Pb 26,000 tons and Zn 50,000 tons based on metal respectively. Major Pb-Zn mines are Gumdock and Seongcheon mines. Magnesite ore reserves(or resources) are 2.8 billion tons (95% MgO) and annual production is about 150,000 tons. Major magnesite mines are Ryongyang, Daeheung Youth and Ssangryong mines, and 5 magnesium refractory factories are operating. Apatite ore reserves(or resources) are 340 million tons(30% $P_2O_5$) and annual production is about 300,000 tons(crude ore). Major apatite mines are Daedaeri, Dongam and Poongnyen mines. Coal is established as an important strategic fuel mineral resources and is a major energy source in North Korea. Coal ore reserves(or resources) are 18.6 billion tons and annual production is about 20 million tons. The main coal fields is located in southern Pyongan and the Jigdong mine is the biggest in North Korea.

• The Journal of the Petrological Society of Korea
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• v.3 no.2
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• pp.156-170
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• 1994

The talc ore deposits can be divided into chloritic and dolomitic ores according to mineral assemblages. The former is mainly composed of chlorite and talc accompanied with dolomite, muscovite and opaque mineral, and the latter of dolomite and talc with serpentine, calcite and magnesite in places. Talc was originated from chlorite and serpentine. Carbonate minerals were formed either directly from the introduced hydrothermal solution or secondarily as a by-product of steatitization of chlorite and serpentine. The process of talc formation may be governed by the chemical composition of the host rocks and the amount and/or chemical composition of the hydrothermal solution which may be different in places. However, the representative reactions producing talc from chlorite and serpentine are as follows : (1) chlorite+$Mg^{++}+Si^{4+}+H_2O$=talc, (2) chlorite+$Mg^{++}+Si^{4+}+Ca^{++}+CO_2+O_2+H_2O$=talc+ dolomite+ magnesite, and (3) serpentine +$Mg^{++}+Fe^{++}+Si^{4+}+Ca^{++}+CO_2+H_2O$=talc+dolomite. The reactions indicate that the carbonate minerals can be formed when the hydrothermal solution have high $fO_2$ and $fCO_2$. The steatitization might be proceeded by the hydrothermally metasomatic reaction between chlorite schist or chlorite gneiss intercalated in the granitic gneiss and hydrothermal solution accompanied to the wet granitization.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.331-342
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• 2009

Groundwater samples were collected from the bedrock aquifers related with Okcheon metasedimentary rocks. Arsenic (As) concentrations in the samples varied between 0.0051 and 0.887 mg/L, with an average of 0.0248. Cations and anions of groundwaters had no relationship with As contents as well as with spatial distribution of geology in the area. Pyrite, chalcopyrite and arsenopyrite in the core samples of the monitoring wells were identified in thin section, X-ray diffraction (XRD) and electron probe microscope analysis (EPMA). It was suggested that these minerals are responsible for the As in groundwater. The groundwater showed saturations with respect to calcite $(CaCO_3)$, dolomite (CaMg$(CO_3)_2$) and Magnesite $(MgCO_3)$. $HAsO_4{^{2-}}$ activities in the groundwater samples were close to $Ca_3(AsO_4)_2(c)$ and $Mn_3(AsO_4)_2(c)$ solubility isotherms, indicating that the maximum As contents in groundwater are secondly controlled by the precipitation and dissolution of carbonate minerals due to alkaline and oxic nature of the groundwater (pe+pH>10).