• Title/Summary/Keyword: dolomite

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Talc Mineralization in the Middle Ogcheon Metamorphic Belt (I): with Emphasis of the Stable Isotope Studies of the Dongyang Talc Deposit (중부 옥천변성대내의 활석광화작용 (I): 동양활석광상의 안정동위원소연구를 중심으로)

  • Park, Hee-In;Lee, Insung;Hur, Soondo
    • Economic and Environmental Geology
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    • v.28 no.6
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    • pp.635-646
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    • 1995
  • Mineralized zone in the Dongyang talc deposits occurs on the lowest dolomite member of the Hyangsanri Dolomite belonging to the Ogcheon Supergroup. Ore bodies are emplaced as pipe-like body along the axis of minor folds plunging $40^{\circ}$ to the west developed in these dolomite layers. Amphibolite and chlorite schist are found along the upper or lower contact of all ore bodies (Kim et al., 1963; Park and Kim, 1966). Following the recrystallization and silicification of dolomite, tremolite and tabular and leafy talc(I) of the earlier stage formed, and microcrystalline talc(II) formed in the later stage. Talc(l) and tremolite formed by the reaction between dolomite and the fluid. Whereas talc (II) formed by the reaction between dolomite and fluid, or by the reaction between early formed tremolite and fluid. During the early stage of mineralization, the fluid was the $H_2O-CO_2$ system dominant in $CO_2$, In the later stage, the composition of the fluid changed to $H_2O-NaCl-CO_2$system, and finally to the $H_2O-NaCl$ system. The pressure and temperature conditions of the formation of tremolite associated with talc(I) were 1,640~2,530 bar, and $440{\sim}480^{\circ}C$, respectively. The pressure and temperature condition of talc(II) ore formation was 1,400~2,200 bar, and $360{\sim}390^{\circ}C$, respectively. These conditions are much lower than the metamorphic pressure and temperature of the rocks from the Munjuri Formation located about 5 km to the noJ:th of Dongyang talc deposit ${\delta}^{13}C$ and ${\delta}^{18}O$ values of dolomite which is the host rock of the talc ore deposit are 2.9~5.7‰ (PDB), and -7.4~l6.8‰ (PDB), respectively. These values are little higher than those from the Cambro-Ordovician limestones of the Taebaeksan region, but belong to the range of the unaltered sedimentary dolomite. ${\delta}^{18}O$and ${\delta}D$ values of the talc from Dongyang deposit are 8.6~15.8‰ (vs SMOW), and -65~-90‰ (vs SMOW), respectively, belonging to the range of magmatic origin. These values are quite different from those measured in the metamorphic rocks of Munjuri and Kyemyungsan Formation. ${\delta}^{34}S$ value of anhydrite is 22.4‰ (CDT), which is much lower than ${\delta}^{34}S$ (30‰ vs COT) of sulfate of early Paleozoic period, and indicates the possibility of the addition of magmatic sulfur to the system. Talc ores show the textures of weak foliation and well developed crenulation cleavages. Talc ore deposit in the area is concluded as hydrothermal replacement deposit formed before the latest phase of the deformations that Ogcheon Belt has undergone.

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Mineralogy and Geochemistry of Carbonate Minerals from the Olon Ovoot Gold Mine, Mongolia (몽골 Olon Ovoot 금 광산에서 산출되는 탄산염광물의 산출상태 및 화학조성)

  • Yoo, Bong Chul;Tungalag, Naidansuren;Sereenen, Jargalen;Heo, Chul-Ho;Ko, Sang-Mo
    • Economic and Environmental Geology
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    • v.47 no.2
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    • pp.181-191
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    • 2014
  • Olon Ovoot gold mine, Mongolia, is located in the Omnogobi province which is south 500 km from Ulaanbaatar. The mine area consists of the Devonian Bot-Uul khudag formation, the Upper Devonian intrusions, and the Upper Devonian or the Early Jurassic quartz veins. The quartz veins contain from 1 to 32 g/t gold with an average of 5 g/t gold. The quartz veins vary from 0.2 m to 25 m and are concordant or discordant with foliation of the green-schist. The mineralogy of the quartz veins is simple and consists of mainly of white massive quartz with partly transparent quartz in cavity. Quartz, sericite, chlorite, pyrite and carbonates(ankerite, dolomite and siderite) were observed in the alteration zone. Carbonate minerals occur as disseminated, coarse or fine grains with quartz, sericite, chlorite and pyrite near vein margin or within wall-rock xenoliths in quartz vein. Ankerite is present as later dark grey ankerite(13.51 to 16.89 wt.% FeO) and early white grey ankerite(16.67 to 19.90 wt.% FeO). The FeO contents of early ankerite are higher than those of later ankerite. Dolomite contains from 3.89 to 10.44 wt.% FeO and from 0.10 to 0.47 wt.% MnO. Dolomite is present as dark grey dolomite(4.06 to 6.87 wt.% FeO), light white grey dolomite(6.74 to 7.58 wt.% FeO) and grey white dolomite(7.33 to 10.44 wt.% FeO). The FeO contents of white grey dolomite are higher than those of dark grey dolomite. Siderite contains from 34.25 to 48.66 wt.% FeO, from 6.79 to 14.38 wt.% MgO, from 0.06 to 0.26 wt.% MnO and from 2.08 to 8.08 wt.% CaO.

A Study on Synthesis of Ca and Mg Compounds from Dolomite with Salt Additional React (MgCl2·6H2O) (염 첨가 반응(MgCl2·6H2O)을 이용하여 백운석으로부터 Ca 화합물과 Mg 화합물 합성에 관한 연구)

  • Hwang, Dae Ju;Yu, Young Hwan;Cho, Kye Hong;Lee, Jong Dae
    • Korean Chemical Engineering Research
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    • v.59 no.3
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    • pp.399-409
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    • 2021
  • In order to utilize dolomite as a calcium/magnesium compound material, it was prepared highly reactive calcined dolomite(CaO·MgO) using a microwave kiln (950 ℃, 60 min). The experiment was performed according to the standard of the hydration test (ASTM C 110) and hydration reactivity was analyzed as medium reactivity (max 74.1 ℃, 5 min). Experiments were performed with calcined dolomite and salt (MgCl2·6H2O) (a) 1:1, (b) 1:1.5, and (c) 1:2 wt% based on the hydration reaction of calcined dolomite. The result of X-ray diffraction analysis confirmed that MgO of calcined dolomite increased to Mg(OH)2 as the salt addition ratio increased. After the separating reaction, calcium was stirred at 80 ℃, 24 hr that produced CaCl2 of white crystal. XRD results, it was confirmed calcium chloride hydrate (CaCl2·(H2O)x) and CaO of calcined dolomite and salt additional reaction was separated into CaCl2. And it was synthesized with Ca(OH)2 99 wt% by NaOH adding reaction to the CaCl2 solution, and the synthesized Ca(OH)2 was manufactured CaO through the heat treatment process. In order to prepare calcium carbonate, CaCO3 was synthesized by adding Na2CO3 to CaCl2 solution, and the shape was analyzed in cubic form with a purity of 99 wt%.

Preparation of Spherical Granules of Dolomite Kiln Dust as Gas Adsorbent

  • Choi, Young-Hoon;Huh, Jae-Hoon;Lee, Shin-Haeng;Han, Choon;Ahn, Ji-Whan
    • Journal of the Korean Ceramic Society
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    • v.53 no.1
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    • pp.13-17
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    • 2016
  • It is highlighted that increasing the adsorbent surface area on volumetric basis is very important in providing an easy access for gas molecules. Fine particles around $3{\mu}m$ of soft-burned dolomite kiln dust (SB-DKD) were hydrated to wet slurry samples by ball mill process and then placed in a chamber to use spray dryer method. Spherical granules with particle size distribution of $50{\sim}60{\mu}m$ were prepared under the experimental condition with or without addition of a pore-forming agent. The relationship between bead size of the pore-forming agent and size of SB-DKD particles is the most significant factor in preparation of spherical granules with a high porosity. Whereas addition of smaller beads than SB-DKD resulted in almost no change in the surface porosity of spherical granules, addition of larger beads than SB-DKD contributed to obtaining of the particles with both 15 times larger average pore volume and 1 order of magnitude larger porosity. It is considered that spherical granules with improved $N_2$ gas adsorption ability may also be utilized for other atmospheric gas adsorption.

Sulfation Reaction Kinetics of Pulverized Korean Dolomite and Limestone using Thermogravimetric Analyses (열중량분석을 이용한 국내산 미분 백운석과 석회석의 황화 반응 특성 연구)

  • 박영철
    • Journal of Energy Engineering
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    • v.7 no.2
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    • pp.216-222
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    • 1998
  • Thermogravimetric analyses were conducted by isothermal technique in order to characterize the sulfation reaction of calcined sorbents such as Tanyang dolomite, Yongwol dolomite, Tanyang limestone, and Yongwol limestone. Sulfation reaction for 0.08 mm in particle diameter were carried out with respect to various factors.; isothermal reaction temperatures (650~85$0^{\circ}C$), SO$_2$ concentration (0.38~1%), and oxygen concentration (1.2~6.7%). Measured reaction orders of SO$_2$ concentration, oxygen concentration, and activation energy were 0.3~2.2, 0.22~0.51 and 23.6~36 kJ/mol, respectively. The kinetic equations of sulfation reaction of calcined dolomites were correlated with various factors.

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Effects of Dolomite Liming on Soil Chemistry in Acidic Forest Soils

  • Kim, Chang-Gi;Rhyu, Tae-Cheol;Kim, Joon-Ho
    • The Korean Journal of Ecology
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    • v.26 no.6
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    • pp.327-333
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    • 2003
  • A mixed forest of pines (Pines densiflora and Pinus rigida) and an oak forest (Quercus mongolica) in Mt. Kwanak in Seoul were limed with 1.5 t/ha and 3 t/ha of dolomite in 1993 and investigated the effects of liming on the chemical changes in the 0-5 cm and 5∼10 cm layers of soil from 1994 to 1995. Soil pH values were greater in the limed plots than in the control plot by the unit of 0.1-0.6 in the pine forest and 0.1∼0.2 in the oak forest. Ca concentrations in the limed plots were greater than those in the control plots in both the pine and oak forests. A considerable increase in Mg concentrations in soil was observed in the limed plots. K and Na concentrations in the limed plots appeared to decrease in both the pine and oak forests two years after liming. Although Al concentrations were greater in the limed plots than in the control plot in the pine forest in 1994, there was a tendency of a decrease in the concentration of this metal in the limed plots in 1995. Mn concentrations also tended to decrease in the limed plots in both the pine and oak forests.

The Effects of Calcium-type Catalysts on the Pyrolysis Reaction of Raw Material Resin for Producing from Waste Vinyl to Fuel-oil (폐 농업용 비닐 수지에서 연료유 생성을 위한 원료 수지의 열분해반응에서 칼슘계 촉매의 영향)

  • Bak, Young-Cheol;Choi, Joo-Hong;Cho, Tae-Ho
    • Journal of Energy Engineering
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    • v.17 no.1
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    • pp.8-14
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    • 2008
  • The effects of calcium type catalysts addition on the thermal decomposition of low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) resin have been studied in a thermal analyze. (TGA, DSC) and a small batch reactor. The calcium type catalysts tested were calcinated dolomite, lime, and calcinated oyster shell. As the results of TGA experiments, pyrolysis starting temperature for LDPE varied in the range of $330{\sim}360^{\circ}C$ according to heating rate, but EVA resin had the 1st pyrolysis temperature range of $300{\sim}400^{\circ}C$ and the 2nd pyrolysis temperature range of $425{\sim}525^{\circ}C$. The calcinated dolomite enhanced the pyrolysis rate in LDPE pyrolysis reaction, while the calcium type catalysts reduced the pyrolysis rate in EVA pyrolysis reaction. In the DSC experiments, addition of calcium type catalysts reduced the melting point, but did not affect to the heat of fusin. Calcinated dolomite reduced 20% of the heat of pyrolysis reaction. In the batch system experiments, the mixing of calcinated dolomite and lime enhanced the yield of fuel oil, but did not affect to the distribution of carbon numbers.

Kinetic study on Low-rank Coal Including K2CO3, Na2CO3, CaCO3 and Dolomite Gasification under CO2 Atmosphere (이산화탄소 분위기에서 K2CO3, Na2CO3, CaCO3 및 Dolomite가 첨가된 저급탄의 가스화에 대한 반응특성연구)

  • Hwang, Soon Choel;Kim, Sang Kyum;Park, Ji Yun;Lee, Do Kyun;Lee, Si Hyun;Rhee, Young Woo
    • Clean Technology
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    • v.20 no.1
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    • pp.64-71
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    • 2014
  • We have investigated the effects of various additives on Eco coal gasification under $CO_2$ atmosphere. The temperature ranges from $750{\sim}900^{\circ}C$ and the gasification experimental was carried out with Eco coal adding 7 wt% $K_2CO_3$, $Na_2CO_3$, $CaCO_3$, Dolomite, and non-additive under $N_2$ and $CO_2$ gas mixture. At $850^{\circ}C$, we observed that the reaction rate increased when the concentration of $CO_2$ increased. However, we also observed that the increment of reaction rate was small at more than 70% of the concentration of $CO_2$. The additives activity was ranked as 7 wt% $Na_2CO_3$ > 7 wt% $K_2CO_3$ > non-additive > 7 wt% Dolomite > 7 wt% $CaCO_3$ at $850^{\circ}C$. At the temperatures of $750^{\circ}C$, $800^{\circ}C$, $850^{\circ}C$, and $900^{\circ}C$, when the temperature increased, the gasification rate increased. The gasification was suitably described by the volumetric reaction model. Using volumetric reaction model, the activation energy of Eco coal including 7 wt% $Na_2CO_3$ gasification was 83 kJ/mol, which was the lowest value among all the alkaline additives.

Stratigraphy and Geological Structure of the Northwestern Okcheon Metamorphic Belt Near the Chungju Area (충주지역 북서부 옥천변성대의 층서 및 지질구조)

  • Ryu, In-Chang;Kim, Tae-Hoon
    • Economic and Environmental Geology
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    • v.42 no.1
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    • pp.9-25
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    • 2009
  • The Northwestern Okcheon Metamorphic Belt in the Chungju area consists of the Munjuri Formation, the Daehyangsan Quartzite, the Hyangsanri Dolomite, and the Gyemyeongsan Formation, but the stratigraphy is still controversial. For a stratigraphic study, detailed stratigraphic sections were measured in two locations and mapping was carried out in the study area. The Munjuri Formation and the Daehyangsan Quartzite changed gradually in north and south section, but bedding parallel faults have developed in the boundary between two formations. The Daehyangsan Quartzite and the Hyangsanri Dolomite are conformable. Fault have developed in boundary between the Hyangsanri Dolomite and the Gyemyeongsan Formation. As a result of mapping in the study area, folding was recognized with $41^{\circ}/280^{\circ}$ plunging axis in the north part of the study area. Therefore, the bedding-parallel faults in the boundary might have occurred resulting from a layer parallel slip during the folding as well as the thrust. These results from this study and previous studies indicate that bedding-parallel faults in boundary between the Munjuri Formation and the Daehyangsan Quartzite are caused by a layer parallel slip during the folding. The fault between the Hyangsanri Dolomite and the Gyemyeongsan Formation is considered as a thrust fault, thereby the uppermost Gyemyeongsan Formation is placed under the Munjuri Formation. However the Gyemyeongsan Formation and the Munjuri Formation have similar age and rock composition. Hence, the Gyemyeongsan Formation is considered as an equivalent one with the Munjuri Formation. Therefore, the stratigraphy of Northwestern Okcheon Metamorphic Belt consists of the Gyemyeongsan/ Munjuri formations, the Daehyangsan Quartzite, and the Hyangsanri Dolomite in ascending order.

Evaluating Heavy Metal Stabilization Efficiency of Chemical Amendment in Agricultural Field: Field Experiment (안정화제 처리에 따른 중금속 오염 농경지 복원의 효율성 평가: 현장실증시험)

  • Oh, Se-Jin;Kim, Sung-Chul;Yoon, Hyun-Soo;Kim, Ha-Na;Kim, Tae-Hwan;Yeon, Kyu-Hun;Lee, Jin-Soo;Hong, Sung-Jo;Yang, Jae-E.
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.6
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    • pp.1052-1062
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    • 2011
  • Residual of heavy metals originated from abandoned metal mines in agricultural field can cause adverse effect on ecosystem and eventually on human health. For this reason, remediation of heavy metal contaminated agriculture field is a critical issue. In this study, five different amendments, agriculture lime, dolomite, steel slag, zeolite, and compost, were evaluated for stabilization efficiency of heavy metals in agricultural field. Applied mixing ratio of amendments was varied (2% or 6%) depending on properties of amendments. Result showed that soil pH was increased compared to control (6.1-6.7) after mixing with amendments and ordered as dolomite (7.2~8.3) > steel slag (6.7~8.1) > agriculture lime (6.6~7.4) > zeolite (6.2~6.9) > compost (6.1~7.1). Among other amendments, agriculture lime, steel slag, and dolomite showed the highest stabilization efficiency of heavy metals in soil. For Cd, stabilization efficiency was 49~72%, 51~83%, and 0~36% for agriculture lime, steel slag, and dolomite respectively. In case of Pb, 43~64, 37~73%, and 51~73% of stabilization efficiency was observed for agriculture lime, steel slag, and dolomite respectively. However, minimal effect of heavy metal stabilization was observed for zeolite and compost. Based on result of this study, amendments that can increase the soil pH were the most efficient to stabilize heavy metal residuals and can be adapted for remediation purpose in agricultural field.