• Economic and Environmental Geology
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• v.35 no.1
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• pp.25-41
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• 2002

In order to investigate the hydrogeochemical characteristics and contamination of dissolved major ions and heavy metals in the Tancheon River, river water and sediment samples were collected at 18 locations, along a distance of 69 km, between Yongin-si in Kyunggi-do and Samsung-dong in Seoul on October in 2000 and April in 2001. After appropriate sample preparation, waters were analyzed for the dissolved constituents and sediments. The pH values of river waters were in the range of 7.0 to 9.3 and could be plotted in the area of surface environment. The level of $Ca^{2+}$, , CI-, sol-, N0$_{3}$ and HC0$_{3}$ in the Tancheon River were higher than those in world average river water. Most of dissolved constituents in the river waters increased toward downstream from upstream. In particular, high concentrations of Zn2+, Na$_{+}$, CI$^{-}$, SO$_{4}^{2-}$ and N03- were found near densely residential areas and the Sungnam waste water treatment plant. The relative ion enrichment was caused by the inflow of local domestic and industrial sewages. Also, Ca2+ and HC03- concentrations were enriched in the middle of the Tancheon River due to the dissolution of cements. This indicates that the apartment complexes were built on a large scale in the upriver since these ten years and large amounts of construction materials such as cements were flowed into the Tancheon River. Concentrations of heavy metals (Mn, Cd, Cu, Pb, Zn) in sediments from the Tancheon River exceeded the lower limit of tolerence level in bottom sediment established by the Ontario Ministry of the Environment (OME) of Canada. In particular, these metals were highly elevated in sediment (TSM-12) collected from near the Sungnam waste water treatment plant. Heavy metals were higher enriched in sediments collected from dry period rather than wet period.

• Resources Recycling
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• v.9 no.4
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• pp.16-27
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• 2000

In order to produce raw material powder of advanced magnetic material by spray roasting process, newly modified spray roasting system was developed in this work. In this spray roasting system, raw material solution was effectively atomized and sprayed into the reaction furnace. Also, uniform temperature distribution inside reaction furnace made thermal decomposition process fully completed, and produced powder was effectively collected in cyclone and bag filter. This system equipped with apparatus which can purify hazard produced gas. In this study complex acid solution was prepared by dissolution of mill scale and ferro-Mn into the acid solution, and the pH of this complex acid solution was controlled about to 4. It was conformed that mill scale and ferro-Mn containing a lot of impurities such as $SiO_2$, P and Al could be used as raw material by reducing the impurities content of complex acid solution below 20 ppm. Complex oxide powder of Fe-Mn system was produced by spraying purified complex acid solution into the spray roaster through nozzle, and the variations of produced powder characters were studied by changing he reaction conditions such as reaction temperature, the injection velocity of solution and air, nozzle tip size and concentration of solution. The morphology of produced powder had spherical shape under the most experimental conditions, and concentration of solution. The morphology of produced powder has spherical shape under the most experimental conditions, and the composition and the particle size distribution were almost uniform, which tells the excellence of this spray roasting system. The grain size of most produced powder was below 100 nm. From the above results, it will be possible to produce ultra fine oxide powder from the chloride of Fe, Mn, Ni, Cu and rare earth by using this spray roasting system, and also to produce ultra fine pure metal powder by changing reaction atmosphere.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.42-51
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• 2004

Peat humin(p-Humin), humic acid(p-HA) and fulvic acid(p-FA) were isolated from Canadian Sphagnum peat moss by dissolution in 0.1M NaOH followed by acid precipitation. After purification cycles, they are characterized for their elemental compositions and, acid/base properties. Functionalities and carbon structures of the humic fractions were also characterized using FT-IR and solid state $^{13}C$-NMR spectroscopy. Those results are compared with one another and with soil humic substances from literatures. Main purpose of this study was to present a chemical and spectroscopic characterization data of humic substance from peat moss needed to evaluate its environmental applicability. The relative proportions of the p-Humin, p-HA and p-FA in the peat moss was $76\%,\;18\%,\;and\;3\%$, respectively, based on the total organic matter content ($957{\pm}32\;g/kg$). Elemental composition of p-Humin were found to be $C_{1.00}H_{1.52}O_{0.79}N_{0.01}$ and had higher H/C and (N+O)/C ratio compared to those of p-HA($C_{1.00}H_{1.09}O_{0.51}N_{0.02}$) and p-FA($C_{1.00}H_{1.08}O_{0.65}N_{0.01}$). Based on the analysis of pH titration data, there are two different types of acidic functional groups in the peat moss and its humic fractions and their proton exchange capacities(PEC, meq/g) were in the order p-FA(4.91) >p-HA(4.09) >p-Humin(2.38). IR spectroscopic results showed that the functionalities of the peat moss humic molecules are similar to those of soil humic substances, and carboxylic acid(-COOH) is main function group providing metal binding sites for Cd(II) sorption. Spectral features obtained from $^{13}C$-NMR indicated that peat moss humic molecules have rather lower degree of humification, and that important structural differences exist between p-Humin and soluble humic fractions(p-HA and p-FA).

• Proceedings of the Mineralogical Society of Korea Conference
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• 2001.06a
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• pp.38-39
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• 2001

The seasonal changes in pH, Fe, Al and SO$_4$$\^$2-/ contents of acid drainage released from coal mine dumps play a major role in precipitation of metal hydroxides in the Taebaek coal field area, southeastern Korea. Precipitates in the creeks underwent a cycle of the color change showing white, reddish brown and brownish yellow, which depends on geochemical factors of the creek waters. White precipitates consist of Al-sulfate (basaluminite and hydrobasaluminite) and reddish brown ones are composed of ferrihydrite and brownish yellow ones are of schwertmannite. Goethite coprecipitates with ferrihydrite and schwertmannite. Ferrihydrite formed at higher values than pH 5.3 and schwertmannite precipitated below pH 4.3, and goethite formed at the intermediate pH range between the two minerals. With the pH being increased from acid to intermediate regions, Fe is present both as schwertmannite and goethite. From the present observation, the most favorable pH that basauluminte can precipitate is in the range of pH 4.45-5.95. SEM examination of precipitates at stream bottom shows that they basically consist of agglomerates of spheroid and rod-shape bacteria. Bacteria species are remarkably different among bottom precipitates and, to a less extent, there are slightly different chemical compositions even within the same bacteria. The speciation and calculation of the mineral saturation index were made using MINTEQA2. In waters associated with yellowish brown precipitates mainly composed of schwertmannite, So$_4$ species is mostly free So$_4$$\^$2-/ ion with less AlSo$_4$$\^$+/, CaSo$\sub$(aq)/, and MgSo$\sub$4(aq)/. Ferrous iron is present mostly as free Fe$\^$2+/, and FeSo$\sub$4(aq)/ and ferric iron exists predominantly as Fe(OH)$_2$$\^$+/, with less FeSo$\sub$4(aq)/, Fe(OH)$_2$$\^$-/, FeSo$_4$$\^$-/ and Fe$\^$3+/, respectively Al exists as free Al$\^$3+/, AlOH$_2$$\^$-/, (AlSo$_4$)$\^$+/, and Al(So$_4$)$\^$2-/. Fe is generally saturated with respect to hematite, magnetite, and goethite, with nearly saturation with lepidocrocite. Aluminum and sulfate are supersaturated with respect to predominant alunite and less jubanite, and they approach a saturation state with respect to diaspore, gibbsite, boehmite and gypsum. In the case of waters associated with whitish precipitates mainly composed of basaluminite, Al is present as predominant Al$\^$3+/ and Al(SO$_4$)$\^$+/, with less Al(OH)$\^$2+/, Al(OH)$_2$$\^$+/ and Al(SO$_4$)$\^$2-/. According to calculation for the mineral saturation, aluminum and sulfate are greatly supersaturated with respect to basaluminite and alunite. Diaspore is flirty well supersaturated while jubanite, gibbsite, and boehmite are already supersaturated, and gypsum approaches its saturation state. The observation that the only mineral phase we can easily detect in the whitish precipitate is basaluminite suggests that growth rate of alunite is much slower than that of basaluminite. Neutralization of acid mine drainage due to the dilution caused by the dilution effect due to mixing of unpolluted waters prevails over the buffering effect by the dissolution of carbonate or aluminosilicates. The main factors to affect color change are variations in aqueous geochemistry, which are controlled by dilution effect due to rainfall, water mixng from adjacent creeks, and the extent to which water-rock interaction takes place with seasons. pH, Fe, Al and SO$_4$ contents of the creek water are the most important factors leading to color changes in the precipitates. A geochemical cycle showing color variations in the precipitates provides the potential control on acid mine drainage and can be applied as a reclamation tool in a temperate region with four seasons.