• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.151-164
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• 2011

Mineralogical and petrological characteristics were investigated on matrix of dense gray, vesiculate gray, brown and black pumice in Ulleung Island by using XRD, FT-IR, XRF, SEM and thermal analysis. According to the analysis, most of pumice matrix are amorphous and include very small amount of sanidine and anorthoclase. Since the adsorption moistures, which commonly observed as O-H peak in FT-IR spectrum, are not identified in thermal analysis, it seems reasonable to conclude that content of the adsorption moisture has very low level. Although pumice has a large specific surface area, with long time elapsed after eruption, pumice matrix shows very low degree of hydration alteration due to the low level of water content. In SEM images, most surfaces of pumice show morphological characteristics such as various shapes of vesicle with wrinkled and thin walls resulted from ductile coalescence. Dense gray pumice formed in the initial stage includes small vesicles less than $15{\mu}m$ in size with subangular to angular shapes, free of ovoid vesicle. These characteristics are interpreted to have related to the hydrous environment derived from phreato-plinian eruption. Submicron particles observed as amorphous alumina silicate assemblages in vesicle surface are considered as particles sticked to the matrix surface through rapidly cooling process during ascent of alkali phonolitic magma. It indicates that these particles coexisted partly with crystallized alkali feldspar.

• Economic and Environmental Geology
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• v.26 no.3
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• pp.363-370
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• 1993

Various sizes of dolerite sills occur in the Mungyong area, one of well-exposed areas in Okchon belt. All of previous geochemical studies concluded that chemical variations of basic rocks, so-called Sangnae-ri amphibolite, result from the fractional crystallization. The second sill, which is a well differentiated one in the Sangnae-ri area, displays systematic compositional variation associated with gradual change of grain size in vertical sections. In order to clarify the chemical variation in the sill, whether chemical composition of each part of the sill is appropriately derived from the original liquid (represented by the average composition) by addition or subtraction of initial phenocystic minerals are tested(Iwamori program, 1989). According to the calculation, it is shown that major vertical chemical variation of the sill resulted from the accumulation of phenocrysts(olivine, clinopyrxoene, plagioclase, titanomagnetite) which already existed at the time of emplacement or formed just after the emplacement.

• Journal of the Mineralogical Society of Korea
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• v.21 no.1
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• pp.45-56
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• 2008

This study was carried out to determine the effects of mineral composition and grain size of zeolite and bentonite from Po-hang and Kyung-ju, South Korea on the adsorption of heavy metals. Zeolite specimen consists mainly of mordenite, clinoptilolite, heulandite etc. And bentonite specimen is mainly composed of montmorillonite. Five heavy metals, Cd, Cr, Cu, Mn, and Pb were used to conduct the relevant adsorption experiments with the fixed concentrations of 10 ppm and 20 ppm, respectively. Host specimens excluding specimen for Cr resulted in the adsorption rate over average 80 percent, and over 95 percent for Pb. This study indicates that zeolite is more efficient in the adsorption of the heavy metals than bentonite, and its adsorption rate tends to decrease with increasing concentration of the heavy metals.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.189-194
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• 2011

Martian satellite missions indicate that Martian equatorial plains are covered by ferric iron oxide. As a non-destructive technique, low-temperature treatment of remanent magnetization is effective in identifying magnetic minerals in rocks. In the present study, four sets of ferric iron oxides were prepared by aqueous alteration of ferrihydrite at warm conditions and four others by dehydration of goethite. As the amount of aluminous trivalent cations increases, crystallographic lattice parameters and N$\acute{e}$el temperatures decrease. Such declines originate from lattice distortion as the smaller aluminous trivalent cations substitue the larger terric irons. Whilst high remanence memory was observed for aqueously produced ferric iron oxide, low remanence memory was observed for dehydrated ferric iron oxide. In the future. magnetic remanence memory would be powerful in diagnosing the origin of ferric iron oxide.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.217-224
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• 2011

Removal of dissolved selenium by D. michiganensis, a iron-reducing bacterium, and effects of dissolved metal elements such as iron, sulfate, and copper were investigated. Selenide that was reduced from selenite (2 mM) by D. michiganensis was gradually removed from the aqueous medium. As the reduced selenide was combined with aqueous iron, it was precipitated as a nanoparticulate iron-selenide. Sulfate and copper negatively affected the microbial selenite reduction, and the copper was especially toxic to the bacterium, inhibiting a microbial removal of dissolved selenite. These results show that it should be carefully biotreated for a selenium-contaminated site considering in situ sulfate or copper distribution and concentration. Consequently, the formation of iron-selenide by bacteria will be an important measure for preventing a long-distance migration of selenium in the subsurface environments.

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.47-55
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• 2018

Talc, hydrous magnesium phyllosilicate, is one of the most popular industrial minerals due to their chemical stability and adsorptivity. While micro-sized talc has long been used as a filler and coating, nano-sized talc recently is attracting attention as additives for improving the stability of nanocomposites. In this study, we produced the nano-sized talc powder by mechanical method using high energy ball mill and investigated the changes in particle size and crystallinity with increasing milling time up to 720 minutes. X-ray diffraction results show that the peak width of talc gradually as the milling proceeded, and after 720 minutes of pulverization, the talc showed an amorphous-like X-ray diffraction pattern. Lase diffraction particle size analysis presents that particle size of talc which was ${\sim}12{\mu}m$ decreased to ${\sim}0.45{\mu}m$ as the milling progressed, but no significant reduction of particle size was observed even after grinding for 120 minutes or more. BET specific surface area, however, steadily increases up to the milling time of 720 minutes, indicating that the particle size and morphology change steadily as the milling progressed. Scanning electron microscope and transmission electron microscope images shows that layered particles of about 100 to 300 nm was aggregated as micro-sized particles after pulverization for 720 minutes. As the grinding time increases, the particle size and morphology of talc continuously change, but the nano-sized talc particles form micro sized agglomerates. These results suggest that there is a critical size along the a, b axes in which the size of plates is reduced even though the grinding proceeds, and the reduction of plate thickness along the c axis leads the increase in specific surface area with further grinding. This study could enhance the understanding of the mechanism of the formation of nano-sized talc by mechanical grinding.

• Proceedings of the Costume Culture Conference
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• 2003.04a
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• pp.103-104
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• 2003

황토는 주로 가는 모래로 되어 있어서 다량의 석영, 장석, 운모 등 다양한 광물 입자로 구성되어 있고 탄산칼슘(CaCO₃), 철(Fe), 마그네슘(Mg), 나트륨(Na), 칼리(K) 등의 성분으로 되어 있다. 황토는 다양한 약성원소를 포함하고 있다. 그것은 특히 제독 능력을 높여줄 뿐 아니라 항균 작용도 하며, 지혈제인 동시에 응고제로 매우 뛰어난 치료효과를 보여준다. 황토의 효능은 숯의 효능과 다를 바가 없으며, 어느 것이 더 우월한 지에 대한 비교를 할 수 없을 정도로 그 약성에 있어서 유사하다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2002.04a
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• pp.313-316
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• 2002

고분자 물질과 유리섬유, 운모, 탄산 칼슘 그리고 점토 광물과 같은 다양한 무기물과의 복합체는 기계적 성질, 열적 성질과 같은 물리적 특성의 향상을 가져올 뿐만 아니라 이와 같은 특성들을 적은 비용으로 향상시킬 수 있는 장점을 가지고 있기 때문에 다양한 방면에서 널리 사용된다[1]. 이에 대해서, 최근 많은 발전을 이루고 있는 나노기술을 고분자와 무기 나노 입자의 복합체에 적용시키는 연구가 활발히 진행되고 있다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.213-213
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• 2000

점토살포에 의한 적조생물 구제효과가 알려지면서, 점토광물로 구성되어있는 산야토양 성분인 황토의 적조구제에 대한 관심도가 매우 높아지고 있으며, 최근 한국에서는 대규모로 발생되고 있는 Cochlodinium polykrikoides 적의 구제물질로서 황토를 대량 사용하고 있다. 그러나 황토의 적조구제 효율은 약 20∼80% 범위로서, 황토의 종류, 입자크기 및 살포방법 등에 따라 큰 차이를 보이고 있다. 이에 황토의 적조구제효과를 증진시키려는 일련의 노력들이 활발히 이루어지고 있다. (중략)

• Journal of the KSME
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• v.21 no.3
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• pp.166-174
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• 1981

광물질(회분, 석회석 또는 모래) 입자의 "유동층" (fuidised bed)에 연료를 유입하여 연소시키는 소위 "유동층 연소" 기술은 최근 몇년동안 상당한 발전을 보이고 있다. 왜냐하면 유동층 연소는 특히 저발열량 연료 (저질탄, 쓰레기등)의 연소에 있어서 여러 가지 장점을 갖고 있기 때문이다. 저질탄의 연소에 있어서 이 유동층 연소 기술이 갖는 장점을 열거하면 다음과 같다. a) 회분성분이나 비활성(inert) 성분의 조성이 균일하지 않은 저질탄의 연소능력 b) 열전달 면에서 부식문제의 저하 c) 보통 미분연소때보다 입도가 커도 완전연소가 가능하므로 분탄제조비가 저렴 여기서는 이러한 장점을 가진 저질탄의 유동층 연소에 대해서, International Energy Agency에서 1978년 발행된 Combustion of low grade coal 보고서를 중심으로 살펴보기로 한다. 보고서를 중심으로 살펴보기로 한다.