배인국 Bae In Gug , 장영남 Jang Yeong Nam , 채수천 Chae Su Cheon , 류경원 Lyu Gyeong Won , 최상훈 Choe Sang Hun

DOI: Vol.16(No.2) 125-133, 2003

Saponite was synthesized from talc by hydrothermal method. The starting material was prepared by adding Al(N0₃)₃·9H₂0 and Mg(N₃)₂·6H₂O solution to the talc powder, which was previously activated in air at 800℃ together with Na₂C0₃. The alkalinity of the solution was controlled by NH₄0H solution. The autoclaving was carried out in the closed stainless steel vessel (about 1 liter) for 40 hours under the pressure of 25 ㎏f/㎠ at 230℃. The characterization of the reaction product shows that saponite was crystallized successfully. After the experimental results, pressure was not sensitive parameter in the range of 25-75 ㎏f/㎠, but longer reaction time results in better crystallinity.

수열합성, 사포나이트, 활석, 스멕타이트, 합성변수, hydrothermal synthesis, saponite, talc, smectite, synthetic parameter

노진환 No Jin Hwan

DOI: Vol.16(No.2) 135-149, 2003

Domestic zeolite ores are mostly composed of Ca-type clinoptilolite, accompanying a little amounts of mordenite. However, other types of zeolite ores rich in ferrierite, heulandite, or mordenite are less commonly found. Based on the quantitative XRD analysis, zeolite contents are determined to be nearly 50-90 wt%. Impurities (mostly > 10 wt%) in the zeolite ores chiefly consist of quartz, feldspar, smectite, and opal-CT. The determined CEC values (CEC_(AA)) of powdery samples (grain size: < 125 ㎛) of zeolite ores by the Ammonium Acetate method are mostly hgher than 100 meq/100g. Some zeolites from the Guryongpo area, corresponding to the clinoptilolite ore, are measured to be dominantly high in CEC values ranging 170-190 meq/100g. Cation exchange property of the zeolite ores varies greatly depending on the types of zeolite species present in the ores. Despite of the lower grade in zeolite content, the CEC_(AA) of ferrierite ore is comparatively high. Compared to this, the CEC_(AA) of heulandite ore is very low, though the zeolite ore exhibits the highest grade ranging up to about 90 wt%. In addition, the CEC values calculated theoretically from the framework composition of clinoptilolite-heulandite series are not consistent with those determined by the cation exchage experiment. The measured CEC_(AA) of clinoptilolite ores are generally higher than those of heulandite ores. This may be due to the higher Ca abundance in exchangeable cation composition and the presence of probable stacking faults in heulandite. The variation of CE_(AA) is roughly proportional, though not strictly compatible, to the zeolite contents in clinoptilolite ores. It seems to be caused by the fact that the CEC_(AA) of clinoptilolite locally varies depending on crystal-chemical diversity, i.e., the variation in framework composition (Si/Al) and exchangeable cation composition (especially, the contents of Ca and K). In addition, the determined CEC values (CEC_(MB)) of zeolite ores by the Methylene Blue method are much higher than those calculated from smectite contents. It suggests a probable reaction of Methylene Blue ion (C_(16)H_(18)N₃S^(+)) with larger-pore zeolites than clinoptlolite-heulandite series, ie., ferrierite and mordenite as well as with smectite. This can be supported by the fact that the ferrierite ore accompanying little amount of smectite has the highest value in CEC_(MB).

제올라이트, 양이온 교환특성, X-선 회절 정량분석, 골격조성, 클리놉틸로라이트, 휼란다이트, 모오데나이트, 페리어라이트, zeolite, cation exchange property, CEC, quantitative XRD analysis, framework composition, clinoptilolite, heulandite, mordenite, ferrierite

김영규 Kim Yeong Gyu

DOI: Vol.16(No.2) 151-159, 2003

^(31)P NMR and XRD have been used to study the mineralogical compositions and the phosphorus species in marine sediments near Wolsung nuclear power plant. The core samples with 30 cm depth were investigated and no mineralogical changes have been found. The studied marine sediments were composed of quartz, albite, microcline, calcite, and some clay minerals such as illite, smectite, chlorite, and kaolinite. Only orthophosphate-monoester and very small amount of ortho-phosphate-diester were identified as phosphorus species in the studied sample, different from the species reported in other countries. These phosphorus species are mainly from organisms and was exposed to the oxic conditions. The consistent mineralogical compositions as well as the same phosphorus species throughout the entire core samples indicate that the constant oxic condition was kept without any changes in sedimentary conditions or the sediments were deposited with different sedimentary conditions, but later they were disturbed by other activities and exposed to the surface oxic conditions continuously.

해저퇴적물, 31P NMR, XRD, marine sediment, orthophosphate-monoester

김영호 Kim Yeong Ho

DOI: Vol.16(No.2) 161-169, 2003

A phase transformation study on a synthetic amorphous diopside, (Ca,Mg)SiO₃ has been carried out up to -30 GPa, and - 1000 7` using a diamond anvil cell and YAG laser heating system, respectively. A starting amorphous material shows a direct transition to cubic (Ca,Mg)SiO₃perovskite at high pressure, which contradicts to the crystalline diopside phase transformation sequence disproportionating into mixtures of the orthorhombic MgSiO₃ perovskite and the cubic CaSiO₃ perovskite phases. This discrepancy might be due to the different starting materials as well as the temperature variations at each specific experiment performed. The present phase transformation sequence would modify the mineralogical assemblage in the Earth transition region and the lower mantle depending upon the pressure, temperature and the oxygen partial pressure.

비정질 투휘석, 다이아몬드앤빌기기, YAG 레이저 가열기기, 폐롭스카이트 상, 상변이 계통, amorphous diopside, diamond anvil cell, YAG laser heating system, perovskite phase, phase transformation sequence

노열 No Yeol , 문지원 Mun Ji Won , 송윤규 Song Yun Gyu , 문희수 Mun Hui Su

DOI: Vol.16(No.2) 171-180, 2003

The objective of this study is to investigate biogeochemical processes to sequester CO₂ and metals utilizing metal-rich fly ash (MRFA). Microbial conversion of CO₂ into sparingly soluble carbonate minerals has been studied using MRFA under different pCO₂ and different bicarbonate concentrations. Scaling from test tube to fermentation vessels (up to 4-L) using metal-reducing bacteria and MRFA has proved successful at sequestering carbon dioxide and metals. CO₂ sequestration via precipitation processes using MRFA may complement the process of CO₂ capture from fossil fuel plants while potentially stabilizing fly ash wastes.

탄소격리, 생광물화 작용, 선탄회, 금속환원 박테리아, carbon sequestration, biomineralization, fly ash, metal-reducing bacteria

정기영 Jeong Gi Yeong

DOI: Vol.16(No.2) 181-189, 2003

Diverse microtextures and secondary minerals formed by chemical weathering were observed in the glacial debris of King George Island. Weathering rind was observed in the block of basaltic andesite tuff due to dissolution of calcite producing voids. Eolian volcanic glass altered to mixtrure of allophane-like materials and iron oxyhydroxides at grain edges with relative concentration of Al, Fe, and Ti. Biotite in granodiorite area was transformed to vermiculite and interstratified biotite-vermiculite or very rarely to kaolinite and gibbsite. Pyrite in the hydrothermal alteration zone was repalced by iron oxides, resulting in sulfuric acid which locally accelerated alteration of chlorite to expandable clay minerals. Weathering of plagioclase and K-feldspar was negligible. Although glacial debris of the Barton Peninsula has undergone weak chemical weathering with formation of some secondary minerals, massive formation of smectite, abundant in nearby marine sediments, didn`t occur.

남극, 빙하쇄설물, 풍화, 조직, Antarctica, glacial debris, weathering, texture

김정진 Kim Jeong Jin , 김수진 Kim Su Jin

DOI: Vol.16(No.2) 191-198, 2003

The ochreous precipitates, reddish brown and brownish yellow in color, are precipitated in the stream bottom of acid mine drainage (AMD) in the Donghae coal mine area. X-ray diffraction analysis shows that the reddish brown precipitate consists mainly of ferrihydrite with small amount of goethite, while the brownish yellow precipitate of schwertmannite. Thermal experiments show that ferrihydrite and schwertmannite partially convert to poorly-crystallized hematite at 400℃ and to well-crystallized hematite at 700℃.

산성광산배수, 페리하이드라이트, 슈워트마나이트, 칠철석, 적철석, acid mine drainage, ferrihydrite, schwertmannite, goethite, hematite