• Journal of the Korean Applied Science and Technology
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• v.26 no.4
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• pp.434-439
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• 2009

This paper is a new method for prevent. The particulate scale. stero-microscope were used for the scale removal experiment to improve mineralogical characteristics and the reduction of scales in heat pipe. Generally, the scale in the heat pipe consists of calcium carbonate minerals, such as calcite and aragonite which are precipitated by the reaction of Ca and $CO_2$ in the water. Copper alloy metal could eliminate the scale and prevent the production of scale in the heat pipe.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.47-48
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• 2016

Mineral carbonation technology is a process whereby CO₂ is chemically reacted with calcium-and/or magnesium-containing minerals to form stable carbonate materials. Add the Materials that could fix CO₂ as mineral admixture to concrete can improve the anti-carbonation properties of concrete. This paper has carried on the literature research on the carbonated mechanism of Material that could fix carbon dioxide. Such as Brucite, 𝜞-C₂S, Mg₂SiO₄, MgO, Ca₃MgSi₂O₈. And summarizes the development of the development of this field.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.4
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• pp.43-47
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• 2009

Soil aggregation is an important part of influencing the soil behaviors in reducing rainfall-runoff and soil erosion, aeration, infiltration, and root penetration. Some inorganic materials such as clay minerals, Fe and Al oxides/hydroxides, and calcium carbonate can act as cementing agents within macroaggregates. The objective of this study was to determine the effects of different cementing agents (Fe, Mn, and Al) on soil aggregate formation in reclaimed tidelands. Water stable aggregate ratio and MWD (mean weight diameter) were higher in iron dioxides treatment than two other treatments. This result indicates significant correlation between soil aggregate formation and iron dioxides.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.173-178
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• 2008

Calcium lactate was prepared by reacting lactic acid with precipitated calcium carbonate (PCC) which was prepared by carbonation process (calcite) and solution process (aragonite). Effects of PCC morphology (calcite and aragonite) on calcium lactate by the solution process were investigated experimentally. Despite the slow forming rate at the initial stage, the final yield of calcium lactate appeared higher when calcite was used. Therefore, the maximum yield of calcium lactate using aragonite was 85.0% and that using calcite was 88.7%, respectively. For both cases, the optimum temperature for the preparation appeared at around $60^{\circ}C$. Furthermore, the increase in lactic acid concentration over 2.0 mol% increased slurry viscosity and deteriorated mass transfer, which resulted in low yield of calcium lactate for both cases. SEM analyses showed that the prepared calcium lactate appeared as plate-like crystal form, irrespective of PCC morphologies, reaction temperatures, and concentrations of lactic acid.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.67-72
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• 2006

Precipitated calcium carbonate (PCC) was prepared in a cylindrical reactor by the nozzle spouting method. The reactor was filled with $CO_2$ and $Ca(OH)_2$ suspensions were circulated through a nozzle to prepare PCC. This method has several advantages such as provision of large contact area between suspension and $CO_2$ and production of large number of nuclei in short time. By changing suspension concentrations, suspension temperature, flow rates of $CO_2$ and nozzle sizes, PCC from homogeneously dispersed $0.1{\mu}m$ to heterogeneous $0.3{\mu}m$ can be obtained. According to XRD analyses, most PCC formed was calcite with small amount of aragonite depending on the reaction conditions. Usually, the reaction proceeded at high pH and electric conductivities initially. Then, pH and electric conductivities decreased rapidly to the saturation condition. Results indicated that the specific conditions (temperature: $25^{\circ}C$, suspension concentration: 0.5 wt%, $CO_2$ flow rate: 1 L/min, nozzle size: 0.4 mm) were required to prepare uniform particle size (particle diameter: $0.1{\mu}m$) of PCC.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.416-424
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• 2023

Concrete emits a large amount of carbon dioxide throughout its life cycle, and due to the societal demand for carbon dioxide reduction, research on storing carbon dioxide in concrete in the form of minerals is ongoing. In this study, cyanobacteria, which absorb carbon dioxide through photosynthesis and fix it as calcium carbonate, were applied to a porous concrete substrate, and the changes in the properties of the concrete substrate due to their special environmental curing condition were analyzed. The results showed that the calcium carbonate precipitation by the microorganisms was concentrated in the light-exposed surface area, and most of the precipitation occurred in the cement paste part, not in the aggregate. This microbially induced calcium carbonate precipitation enhanced the mechanical performance of the paste and improved the overall compressive strength as the curing age progressed. In addition, the increase in microbial biofilm and calcium carbonate improved the pore structure, which influenced the reduction in water permeability.

• 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.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.257-271
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• 2002

One of the main interests in relation to heavily contaminated gully-pot sediment in urban area is the short term mobility of heavy metals, which depends on the pH of acidic rainwater and on the buffering effects of carbonate minerals. The buffering effects of carbonates are determined by titration (acid addition). Leaching experiments are carried out in solutions with variable initial HN03 contents for 24h. The gully-pot sediment appears to be predominantly buffered by calcite and dolomite. In case of sediment samples, which highly contain carbonates, pH decreases more slowly with increasing acidity. On the other hand, for the sediment samples, which less contain carbonate minerals, pH rapidly drops until it reaches about 2 then it decreases slowly. The leaching reactions are delayed until more acid is added to compensate for the buffering effects of carbonates. The Zn, Cu, Pb and Mn concentrations of leachate rapidly increase with decreased pH, while Cd, Co, Ni, Cr and Fe dissolutions are very slow and limited. The solubility of heavy metals depends not only on thc pH values of leachatc but also on the speciation in which metals are associated with sediment particles. In slightly to moderately acid conditions, Zn, Cd, Co, Ni and Cu dissolutions become increasingly important. As deduced from leaching runs, the relative mobility of heavy metals at pH of 5 is found to be: Zn > Cd > Co > Ni > Cu » Pb > Cr, suggesting that moderately acid rainwater leach Zn, Cd, Co, Ni and Cu from thc contaminated gully-pot sediment, while Pb and Cr would remain fixed. The buffering effects of Ca- and Mg-carbonates play an important role in delaying as well as limiting the leaching reactions of heavy metals from highly contaminated gully-pot sediment. The extent of such a secondary environmental pollution will thus depends on how well the metals in sediment can be leached by somewhat acidic rain water. Changes in the physicochemical environments may result in the severe environmental pollution of heavy metals. These results are to be taken into account in the management of contaminated sediments during rainstorms.

• Journal of the Mineralogical Society of Korea
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• v.15 no.3
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• pp.231-240
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• 2002

Microbial metal reduction influences the biogeochemical cycles of carbon and metals as well as plays an important role in the bioremediation of metals, radionuclides, and organic contaminants. The use of bacteria to facilitate the production of magnetite nanoparticles and the formation of carbonate minerals may provide new biotechnological processes for material synthesis and carbon sequestration. Metal-reducing bacteria were isolated from a variety of extreme environments, such as deep terrestrial subsurface, deep marine sediments, water near Hydrothemal vents, and alkaline ponds. Metal-reducing bacteria isolated from diverse extreme environments were able to reduce Fe(III), Mn(IV), Cr(VI), Co(III), and U(VI) using short chain fatty acids and/or hydrogen as the electron donors. These bacteria exhibited diverse mineral precipitation capabilities including the formation of magnetite ($Fe_3$$O_4$), siderite ($FeCO_3$), calcite ($CaCO_3$), rhodochrosite ($MnCO_3$), vivianite [$Fe_3$($PO_4$)$_2$ .$8H_2$O], and uraninite ($UO_2$). Geochemical and environmental factors such as atmospheres, chemical milieu, and species of bacteria affected the extent of Fe(III)-reduction as well as the mineralogy and morphology of the crystalline iron mineral phases. Thermophilic bacteria use amorphous Fe(III)-oxyhydroxide plus metals (Co, Cr, Ni) as an electron acceptor and organic carbon as an electron donor to synthesize metal-substituted magnetite. Metal reducing bacteria were capable of $CO_2$conversion Into sparingly soluble carbonate minerals, such as siderite and calcite using amorphous Fe(III)-oxyhydroxide or metal-rich fly ash. These results indicate that microbial Fe(III)-reduction may not only play important roles in iron and carbon biogeochemistry in natural environments, but also be potentially useful f3r the synthesis of submicron-sized ferromagnetic materials.

• Journal of the Mineralogical Society of Korea
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• v.2 no.2
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• pp.90-99
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• 1989

Manganese deposits ar the Dongnam mine occur as vein in the Pungchon limestone of Ordovician age. Manganese ore veins consist of the hydrothermal manganese carbonate ores in the deeper part and the supergene manganese oxide ores in the shallow part. Manganese carbonate ores consist mainly of rhodochrosite, with minor amount of proxmangite, garnet, calcite, quartz, pyrite, galena and sphalerite. Manganese oxide ores consist of rancieite, buserite, birnessite, vernadite, todorokite, pydrolusite, nsutite, hydrohetaerosite and goethite. Manganese oxide minerals were formed in the following sequences; 1) rhodochrosite ${\rightarrow}$ vernadite ${\rightarrow}$ birnessite ${\rightarrow}$ nsutite ${\rightarrow}$ pyrolusite, 2) pyroxmangite ${\rightarrow}$ birnessite, 3) Buserite ${\rightarrow}$ ransieite. Todorokite, buserite and hydrohetaerolite were precipitated from solution in the later stage. The natural analogue of synthetic buserite has been discovered from the mine. It has been disclosed that buserite transforms to rancicite by dehydration, and that distinction between buserite and todorokite is possible by X-ray diffraction studies combined with dehydration experiment. Minerals identified from the mine have been characterized using various methods including polarizing microscopy, X-ray diffraction, thermal analysis, infrared spectroscopy, X-ray diffraction, thermal analysis, infrared spectroscopy, elecrton microscopy and dehydration experiment.