• Economic and Environmental Geology
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• v.24 no.2
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• pp.97-105
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• 1991

Oxygen and sulfur isotope composition of pyrophyllite and pyrite from six pyrophyllite deposits in the Yangsan-Milyang areas (the Cheonbulsan, Dumyong, Dongrae, Youkwang, Sungjin and Milyang mines), and five deposits in the Whasoon-Dado-Haenam areas (the Byuksong, Songseok, Dado, Bugock and Nowha mines) were measured. Pyrophyllite ores both from the Yangsan-Milyang areas and the Dado-Haenam areas are composed mainly of high alumina minerals such as pyrophyllite, sericite and kaolinite. Most of altered rocks show diagnostic chacteristics of bleaching effect. Major minerals of the Songseok ore deposit in the Whasoon area are pyrophyllite, and diaspore with minor amounts of kaolinite and quartz. The Byuksong ores from the Whasoon area were composed mainly of andalusite, kaolinite, pyrophyllite and mica with small amounts of chloritoid, quartz and carbonaceous matter. The Byuksong and Songseok ores show metamorphic textures such as porphyroblastic, and pressure solution textures, and have low whiteness values, The ${\delta}^{18}O$ values of pyrophyllite from the Cheonbulsan and Dumyong mines in the Yangsan area, and the Dado and Nowha mines in the Dado-Haenam areas were in the range of 0.23~5.36%,. The relatively low 8 180 values provide conclusive evidence for hydrothermal activity in these deposits. The ${\delta}^{18}O$ values of pvrophvllite from the Songseok mine in the Whasoon area were measured as 6.70-8.13%, and these higher ${\delta}^{18}O$ values suggest that the Songseok ore deposit have been probably subjected to metamorphism. ${\delta}^{34}$S(pyrito) values from the Cheonbulsan, Dumyong, Youkwang, Dongrae, Sungjin and Milyang deposits in the Yangsan-Milyang areas, and the Dado pyrophyllite deposits in the Dado area range from -5.8 to 2.7%, which means that the pyrite sulfur could be of igneous origin. ${\delta}^{34}$S(pyrito) from the Nohwa mine in the Haenam area is, however, measured as -12.4%" implying the contamination of sulfur derived from the sedimentary country rocks. All of the studied high alumina deposits in the Yangsan-Milyang areas and the Dado-Haenam areas were hydrothermal in origin, whereas the Byuksong and Songseok ore deposits in the Whasoon area were probably of metamorphic origin.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.68-76
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• 2002

In this study, we have investigated the geochemical behavior and fate of heavy metals in acid rock drainage (ARD). The ARD was collected from the area of the former Dongrae pyrophyllite mine. The Dongrae Creek waters were strongly acidic (pH : 2.3~4.2) and contained high concentrations of $SO_4$, Al, Fe, Mn, Pb, Cu, Zn, and Cd, due to the influence of ARD generated from weathering of pyrite-rich pyrophyllite ores. However, the water quality gradually improved as the water flows downstream. In view of the change of mole fractions of dissolved Fe, Al and Mn, the generated ARD was initially both Fe- and AA-ich but progressively evolved to more Al-rich toward the confluence with the uncontaminated Suyoung River. As the AR3 (pH 2.3) mixed with the uncontaminated waters (pH 6.5), the pH increased up to 4.2, which caused precipitation of $SO_4$-rich Fe hydroxysulfate as a red-colored, massive ferricrete precipitate throughout the Dongrae Creek. Accompanying the precipitation of ferricrete, the Dongrae Creek water progressively changed to more Al-rich toward downstream sites. At the mouth of the Dongrae Creek, it (pH 3.4) mixed with the Suyoung River (pH 6.9), where pH increased to 5.7, causing precipitation of Al hydroxysulfate (white precipitates). Neutralization of the ARD-contaminated waters in the laboratory caused the successive formation of Fe precipitates at pH<3.5 and Al precipitates at higher pH (4~6). Manganese compounds were precipitated at pH>6. The removal of trace metals was dependent on the precipitation of these compounds, which acted as sorbents. The pHs for 50% sorption ($pH_{50}$) in Fe-rich and Al-rich waters were respectively 3.2 and 4.5 for Pb, 4.5 and 5.8 for Cu, 5.2 and 7.4 for Cd, and 5.8 and 7.0 for Zn. This indicates that the trace metals were sorbed preferentially with increasing pH in the general order of Pb, Cu, Cd, and Zn and that the sorption of trace metals in Al-rich water occurred at higher pH than those in Fe-rich water. The results of this study demonstrated that the partitioning of trace metals in ARD is not only a function of pH, but also depends on the chemical composition of the water.