• Journal of the Mineralogical Society of Korea
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• v.2 no.1
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• pp.37-46
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• 1989

X-ray, optical and electron microscope studies exhibit that the amphiboles in anorthositic saprolite from kaolin deposits, located in Suryun-myeon, Seongju-gun, Kyungsangbuk-do, have altered under weathering conditions to smectite, mixed-layer mineral, vermiculite and goethite. In early supergene alteration stage when rock structure is still preserved, smectite occurs as initial weathering product of amphibole. Further weathering leads to the formation of mixed-layer mineral, vermiculite and goethite as indicated by XRD and SEM studies. Scanning electron microscopy studies of amphibole show that the dissolution of amphibole proceeds by selective etching at the surface along weaker zones producing distinct etch pattern, The calcic amphiboles according to electron microprobe analyses, show leaching of the most mobile elements (Mg, Ca and Fe) during alteration.

• Resources Recycling
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• v.7 no.1
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• pp.7-13
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• 1998

The electric arc furnace (EAF) dust used in this experiment showed the formation of an irregular agglomerate of small spherical particles and consisted of 27.5% Fe, 18% Zn, 4.83% Pb and 10.2% CaO, and it also contained 3.26% Cl and 0.15% F. IR spectra peaks of Pb(OH)Cl were observed at 1630 and 1377 ${cm}^{-1}$ regions and the intensity decreased using an acid treatment (1N ${H}_{2}{SO}_{4}$) and thermal treatment at above 600℃, but it was not affected by washing process. Those of ${Zn}_{5}{(OH)}_{8}{Cl}_{2}$ treated by oxidation showed broad absorption peak at 3600∼3200 ${cm}^{-1}$, main peaks at 1136 and 1040 ${cm}^{-1}$ and a splitting peak at 991 and 921 ${cm}^{-1}$ which were believed to be due to ZnO by oxidation at about 700∼. The IR spectra of the dust residues by a washing process show the same peaks at 3449, 1635, 1439, 875, 571 and 455 ${cm}^{-1}$ regions, but the peaks at 2942, 2862, 1136 and 1040 ${cm}^{-1}$ decreased and disappeared using an acid treatment and washing process, which is believed to be due to the dissolution of zinc hydroxyl chloride.

• Journal of the Korean Ceramic Society
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• v.41 no.9
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• pp.642-646
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• 2004

Na$_2$Si$_2$O$_{5}$ added to the solution affects the hydration of 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$ with calcium sulfate. The reaction between 4CaOㆍAl$_2$O$_3$ Fe$_2$O$_3$and CaSO$_4$ㆍ 2$H_2O$ decrease with increasing amount of Na$_2$Si$_2$O$_{5}$ in solution, owing to low hydraulic reactivity of 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$by the adsorption of silicate ions on the surface of 4CaOㆍAl$_2$O$_3$ㆍ Fe$_2$O$_3$ particles. The dissolution rate of 4CaOㆍAl$_2$O$_3$ㆍ Fe$_2$O$_3$ particles deceased with the increase of the concentration of silicate ion in solution. When the 4CaOㆍAl$_2$O$_3$ㆍFe$_2$O$_3$ particles was hydrated in gypsum - Na$_2$Si$_2$O$_{5}$ solution, the hydration was retarded and the rate could not discriminate between formation of ettringite and that of monosulfate, and it stopped in high concentration of silicate ions. However, silicate ion did not any effect on the dissolution rate of gypsum.ypsum.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.460-466
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• 2014

To evaluate wood charcoal as raw material for mineral water production, dissolution of inorganic ions from charcoal to water, pH and adsorption ability of chlorine in water were investigated as main variables. More potassium ion was dissolved in water as higher temperature manufactured charcoal but other ions showed no difference with different charcoal making temperatures. Highest dissolved cation was potassium followed by calcium and sodium. Among wood species, charcoal from Quercus variabilis and Platanus occidentalis showed significantly higher potassium content in water than that of larch, red pine and white pine. Other cations had similar pattern to the potassium but their difference was not apparent as much as potassium. pH value of water treated with charcoal was higher for wood charcoals from Platanus occidentalis (pH 8.5) and Quercus variabilis (pH 8.4) which contained higher inorganic cations. In chlorine removal in water by charcoal, all wood charcoals showed greater chlorine removal than that of the control, but softwood charcoals resulted in higher removal than those of hardwoods. There was no significant difference in the dissolution of cations and pHs between particle charcoal and whole charcoal. With easy of control, whole charcoal is better for mineral water making raw material than particle charcoal does.

• Journal of the Korean Magnetics Society
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• v.18 no.5
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• pp.174-179
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• 2008

The measurement dissolution sensor system using GMR-SV device with magnetic sensitivity of 0.8 %/Oe and Mg-film thick of 200 nm and Mg-foil thick of 50 mm was fabricated and characterized. During the water dissolving process of Mg-film and Mg-foil, the subtle variation of magnetic field by the decrease of current in solenoid was detected by the GMR-SV sensor. The variations of Mg bubble number and ORP as a function of time for three different kinds of edible, tap, and distilled water, are measured and compared. A After 45 min, the speed of fast dissolving Mg was shown the order of edible > tap > DI water. The variation of output magnetoresistance as a function of dissolved time of Mg-film and Mg-foil for edible water, which is composed of mineral content of $0.8{\sim}5.4\;mg/l$ was investigated. The response times for the dissolution in edible water were 5 min and 20 min, respectively. From the measurement of dissolving time and speed for Mg-film and Mg-foil using GMR-SV device, the mineral Mg sensor system in edible water can be possible to develop.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.4
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• pp.321-328
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• 2006

A basic research was conducted on the mineral weathering and geochemical characteristics in the KURT (KAERI Underground Research Tunnel), which was recently constructed at a site in KAERI. Some rock samples exposed during the KURT construction were examined using a microscope and chemical analysis for some micro-changes of the rocks caused by the chemical weathering. The weathered granite has some small and fine cracks around the rock-forming minerals. In particular, there are a characteristic weathering of feldspar mineral and a preferential leaching of Ca component from the mineral dissolution. In addition, by the dissolution of biotite containing $Fe^{2+}$ component there were iron-oxides precipitates as secondary products into the microcracks of around minerals. The results also show that the micro-cracks initiated from the mineral interior are extended and connected into the larger cracks along the grain boundary with the progress of the weathering. Thus, it is considered that some chemicals dissolved from the fresh rock would be involved in the formation of secondary minerals and migrate interacting with them.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.517-520
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• 2006

The leaching behaviors of zinc and manganese oxides of spent alkaline manganeses battery in sulfuric acid solution by using $H_{2}O_{2}$ as a reducing agent were investigated according to the concentration of $H_{2}SO_{4}$, temperature, reaction time, and the amount of $H_{2}O_{2}$. The experimental results of zinc and manganeses dissolution rates obtained without a reducing agent at 100 g/L solid/liquid ratio, 3.0 M $H_{2}SO_{4}$, $60^{\circ}C$ and 200 r.p.m. were 97.7% and 43.5%, respectively. On the other hand, zinc and manganeses dissolution rates obtained by adding 30 mL reducing agent at $60^{\circ}C$ were 99.6% and 97.1%, respectively. The addition of the reducing agent increased the leaching of manganese by two-fold compared to the absence of a reducing agent. In case of adding over 30 mL $H_{2}O_{2}$, however, the leaching rates of zinc and manganeses were independent of reducing agent amounts.

• Journal of the Mineralogical Society of Korea
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• v.32 no.2
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• pp.79-86
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• 2019

The white aluminum phases in acid mine drainage usually precipitates when mixed with stream waters with relatively high pH. The minerals in white precipitates play important roles in controlling the behavior of heavy metals by adsorbing and coprecipitation. By the phase transition of these minerals in white precipitates, dissolution and readsorption of heavy metals may occur. This study was conducted to obtain preliminary information on the phase transition of the mineral phases in white precipitates. In this study, the mineral phase changes in the white precipitates collected from the stream around Dogye Mining Site over time were investigated with different pH values and temperatures. White precipitates consist mainly of basaluminite, amorphous $Al(OH)_3$ and a small amount of $Al_{13}$-tridecamer. During aging, the incongruent dissolution of the basaluminite occurs first, increasing the content of the amorphous $Al(OH)_3$. After that, pseudoboehmite is finally precipitated following the precursor phase of pseudoboehmite. At $80^{\circ}C$, this series of processes was clearly observed, but at relatively low temperatures, no noticeable changes were observed from the initial condition with coexisting basaluminite and amorphous $Al(OH)_3$. At high pH, the desorption of $SO{_4}^{2-}$ group in basaluminite was initiated to promote phase transition to the pseudoboehmite precursor. Over time, the solution pH decreases due to the dissolution and phase transition of the minerals, and even after the precipitation of pseudoboehmite, only the particle size slightly increased but no clear cystal form was observed.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.335-342
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• 2009

The effects of bacterial lysis on the rate of quartz dissolution were investigated under pH 7 condition using Bacillus subtilis cells which were either irradiated or non-irradiated with gamma ray. The amount of dissolved organic carbon (DOC) which resulted from bacterial lysis increased in slurries of quartz and bacteria mixture over experimental period. Lysis of non-irradiated bacteria led to the elevated concentration of dissolved silicon when compared with abiotic control. Concomitant increase in the amounts of DOC and dissolved silicon over time indicated that lixiviation of silicon from quartz was due to bacterial lysis. Higher amounts of DOC and dissolved silicon were present in the irradiated bacterial slurries than those of non-irradiated bacteria. The enhancement of quartz dissolution in the irradiated bacterial slurries was likely attributed to disruption of organic molecules in the bacterial cells by gamma ray and formation of effective ligands for quartz dissolution. The results suggest that the effects of bacterial lysis on mineral weathering rate should be considered for prediction of time for released radionuclides to migrate to surface biosphere in high level radioactive waste disposal site.

• Mineral and Industry
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• v.26
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• pp.1-12
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• 2013

In this study, an accelerated carbonation process was applied to stabilize hazardous heavy metals of industrial solid waste incineration (ISWI) bottom ash and fly ash, and to reduce $CO_2$ emissions. The most commonly used method to stabilize heavy metals is accelerated carbonation using a high water-to-solid ratio including oxidation and carbonation reactions as well as neutralization of the pH, dissolution, and precipitation and sorption. This process has been recognized as having a significant effect on the leaching of heavy metals in alkaline materials such as ISWI ash. The accelerated carbonation process with $CO_2$ absorption was investigated to confirm the leaching behavior of heavy metals contained in ISWI ash including fly and bottom ash. Only the temperature of the chamber at atmospheric pressure was varied and the $CO_2$ concentration was kept constant at 99% while the water-to-solid ratio (L/S) was set at 0.3 and $3.0dm^3/kg$. In the result, the concentration of leached heavy metals and pH value decreased with increasing carbonation reaction time whereas the bottom ash showed no effect. The mechanism of heavy metal-stabilization is supported by two findings during the carbonation reaction. First, the carbonation reaction is sufficient to decrease the pH and to form an insoluble heavy metal-material that contributes to a reduction of the leaching. Second, the adsorbent compound in the bottom ash controls the leaching of heavy metals; the calcite formed by the carbonation reaction has high affinity of heavy metals. In addition, approximately 5 kg/ton and 27 kg/ton $CO_2$ were sequestrated in ISWI bottom ash and fly ash after the carbonation reaction, respectively.