• Korean Chemical Engineering Research
• /
• v.49 no.2
• /
• pp.137-150
• /
• 2011

$CO_{2}$ mineral carbonation technology, fixation technology of $CO_{2}$ as carbonates, is considered to be an alternative to the $CO_{2}$ geological storage technology, which can perform small- or medium-scale $CO_{2}$ storage. We provide the current R&D status of the mineral carbonation with special emphasis on the technical and economical feasibility of $CO_{2}$ mineral carbonation taken into consideration of the domestic geological and industrial environment. Given that the domestic industry produces relatively large amount of the industrial by-products, it is expected that the technology play a pivotal role on the $CO_{2}$ reduction countermeasure, reaching the potential storage capacity to 12Mt-$CO_{2}$/yr. The economics of the overall process should be improved via the development of advanced technologies on the pretreatment of raw materials, method/solvents for metal extraction, enhanced kinetics of carbonation reactions, heat integration, and the production of highly value-added carbonates.

• Journal of the Korea Concrete Institute
• /
• v.15 no.6
• /
• pp.829-839
• /
• 2003

Recently, the corrosion of reinforced concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation but the future studies for combined environment will assure the precise assessment.

• Journal of Chest Surgery
• /
• v.29 no.5
• /
• pp.477-486
• /
• 1996

Endogenous analgesic systems are known to be activated by peripheral noxious stimulation as well as arterial carbon dioxide elevation. In the present study, neuronal Activities in the rostral ventrolateral med- ulla were identified and classified in according to their rhythmic activities, and their responses to noxious peripheral nerve stimulations before and after elevating the arterial carbon dioxide partial pressure were investigated Using extracellular recording technic, a total of 53 spontaneously active neurons were recorded from the rostral ventrolateral medulla in u-chloralose anesthetized cats. These were classified as cardiovascular (28), respiratory (16), both cardiovascular and respiratory (2) and noncardiovascular - nonrespiratory (7). - Among the 28 cardiovascular neurons eleven showed increased activities during arterial hypercapnia, thirteen showed decreased responses, and four showed no change. Nine respiratory neurons showed increased responses to arterial hypercapnia, six showed decreased responses and one showed no change. neither of the cardiovascular and respiratory neurons showed significant change in its activity during ar- terial hypercapnia, however, four of the noncardiovascular - nonrespiratory neurons exhibited decreased their activities in response to arterial hypercapnia while two exhibited increased activities. Arterial hypercapnia increased the responses of cardiovascular neurons to peripheral nerve stimulation with C-inteniity, while not changing the responses to Ak_stimulation significantly . From the above results it was conclllded that during arterial hypercapnia, some cardiovascular neurons and respiratory neurons have increased activities as well as increased reponses to C-Hber stimulation.

• Applied Chemistry for Engineering
• /
• v.17 no.1
• /
• pp.67-72
• /
• 2006

Precipitated calcium carbonate (PCC) was prepared in a cylindrical reactor by the nozzle spouting method. The reactor was filled with $CO_2$ and $Ca(OH)_2$ suspensions were circulated through a nozzle to prepare PCC. This method has several advantages such as provision of large contact area between suspension and $CO_2$ and production of large number of nuclei in short time. By changing suspension concentrations, suspension temperature, flow rates of $CO_2$ and nozzle sizes, PCC from homogeneously dispersed $0.1{\mu}m$ to heterogeneous $0.3{\mu}m$ can be obtained. According to XRD analyses, most PCC formed was calcite with small amount of aragonite depending on the reaction conditions. Usually, the reaction proceeded at high pH and electric conductivities initially. Then, pH and electric conductivities decreased rapidly to the saturation condition. Results indicated that the specific conditions (temperature: $25^{\circ}C$, suspension concentration: 0.5 wt%, $CO_2$ flow rate: 1 L/min, nozzle size: 0.4 mm) were required to prepare uniform particle size (particle diameter: $0.1{\mu}m$) of PCC.

• Journal of the Korean Chemical Society
• /
• v.54 no.4
• /
• pp.479-486
• /
• 2010

The purposes of this study are to investigate the description of scientifically debatable carbonic acid in the Korean high school textbooks, characterize the physical properties of 'carbonic acid solutions' by using an MBL set-up and compare the properties with textual ones. Four different aqueous solutions of carbon dioxide have been prepared and analyzed: naturally aerated aqueous solution, dry ice-dissolving solution, $CO_2$-bubbling solution and commercial carbonic acid water. Experimental findings showed that pH and conductivity of these 4 solutions ranged from 3.85 to 5.66 and from 0.21 ${\mu}S$/cm to 272.1 ${\mu}S$/cm, respectively. Out of these solutions, the dissociation constant($K_{a1}$) of the bubbling solution at room temperature could be calculated to $5.7{\times}10^{-7}$ which value is comparable to the textual $4.3{\times}10^{-7}$ within experimental errors, which means that textual compound is not pure carbonic acid but the equilibrated mixture of carbonic acid and the aqueous solution of carbon dioxide. On the other hand, textual analysis showed that most of high school textbooks used carbonic acid as an example of weak acid and buffer solution of the blood but none of them distinguished the carbonic acid from the aqueous solution of carbon dioxide. Only one textbook, however, tiered two species in the chemical equation.

• The Journal of the Petrological Society of Korea
• /
• v.10 no.1
• /
• pp.1-12
• /
• 2001

A small of carbonate rocks and spatially-associated ultramafic rocks uniquely occur in the ulsan iron-serpentine mine of the sourtheastern Kyungsang basin. The study of field geology, core drilling data and stable isotope analysis suggest that the carbonate rocks are carbonatite formed from the melt reflecting intrusive natures. Based on this study, the geology of the Ulsan iron-serpentinite mining area consists of Cretaceous sedimentary, volcanic, granitic ultramafic and carbonate rocks in ascending order. The carbonate and ultramafic rocks show concentric and ellipsoidal shapes at the outcrop and a funnel shape in the cross sectional view. Carbon and oxygen stable isotope analysis show a bimodal pattern rather than a typical mantle pattern, which may indicate that the melt was a secondary melt generated within the crus not in the mantle directly. The uprising of ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crus. Then, the intrusion of the ultramafic melts would have melted lime-contained rocks forming a secondary carbonate melt in the upper crust. Then, the intrusion of the ultramafic melt was followed by the intrusion of the carbonate melt along deep-seated fractures. Well-developed major fractures in this area, fluid inclusion characteristics of the carbonate rocks, the spatial relation between the ultramafic and carbonate rocks and stable isotope data support interpreting the Ulsan carbonate rocks as carbonatite.

• Journal of the Mineralogical Society of Korea
• /
• v.30 no.4
• /
• pp.205-217
• /
• 2017

Mineral carbonation by indirect method has been studied by serpentinite as cation source. Through the carbonation of $CO_2$ and alkaline earth ions (calcium and magnesium) from serpentinite, the pure carbonates including $MgCO_3$ and $CaCO_3$ were synthesized. The extraction solvent used to extract magnesium (Mg) was ammonium sulfate ($(NH_4)_2SO_4$), and the investigated experimental factors were the concentration of $(NH_4)_2SO_4$, reaction temperature, and ratio of serpentinite to the extraction solvent. From this study, the Mg extraction efficiency of approximately 80 wt% was obtained under the conditions of 2 M $(NH_4)_2SO_4$, $300^{\circ}C$, and a ratio of 5 g of serpentinite/75 mL of extraction solvent. The Mg extraction efficiency was proportional to the concentration and reaction temperature. $NH_3$ produced from the Mg extraction of serpentinite was used as a pH swing agent for carbonation to increase the pH value. About 1.78 M of $NH_3$ as the form of $NH_4{^+}$ was recovered after Mg extraction from serpentinite. And, the main step in Mg extraction process of serpentinite was estimated by geochemical modeling.

• Economic and Environmental Geology
• /
• v.52 no.5
• /
• pp.381-393
• /
• 2019

Carbonate breccias occur sporadically in the Middle Cambrian Daegi Formation on the southern limb of the Baegunsan Syncline, Taebaeksan Basin. These carbonate breccias have been largely interpreted either as sedimentary breccias or as tectonic, fault-related breccias. Recent study, however, indicates that the majority of these breccias are a solution-collapse breccia which is causally linked to the paleokarstification. Extensive karstification is attributed to prolonged subaerial exposure of the carbonate platform. The exposed surface is a record of interruption in sedimentation on the carbonate platform. In the stratigraphic record, such karst-related post-depositional features are recognized as meteoric diagenetic features, paleosols, and solution-collapse breccias. Solution-collapse breccias are particularly well preserved and most profound in the carbonate rocks below the major unconformities, which also are evidence of prolonged subaerial exposure. The Middle Cambrian Daegi Formation provides an example of solution-collapse breccias. The formation and preservation of the solution-collapse breccias imply that a stratigraphic discontinuity surface (unconformity) can be designated within the Daegi Formation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2005.04a
• /
• pp.402-404
• /
• 2005

2004년 7월부터 2005년 2월까지 8개월 동안 강원도 정선지역 탄산염지대 지하수 및 하천수의 ${\delta}^{13}C$의 조사 결과, 탄산염 지대 지하수의 13C는 $-12.07{\sim}-8.63$ (평균 -10.34 ), 탄사염지대 하천수의 ${\delta}^{13}C$는 $-10.32{\sim}-6.80$ (평균 -7.944 ) 이었다. 하천수와 지하수 ${\delta}^{13}C$는 수온(T)과 음의 상관관계를 보이고 물의 전기전도도(EC)와 양의 상관관계를 보이며, 여름보다 겨울에 높은 값을 보이는 반면 산화환원 전위(Eh), 용존산소(DO), pH와는 상관관계가 미약함을 보이고 있다. 탄산염지대 지하수 및 하천수의 ${\delta}^{13}C$는 연구지역의 지하수와 하천수가 탄산염암의 용해, 대기 $CO_2$와 용존 $CO_2$의 교환, 유입된 대기 $CO_2$가 물 분자와 반응하여 ${HCO_3}^-$ 이온으로 전환될 때 있는 분별작용의 효과에 의해 주로 영향을 받았으며 수중생물의 신진대사에 의한 변화는 미미한 것으로 나타났다.

• Resources Recycling
• /
• v.12 no.1
• /
• pp.41-47
• /
• 2003

In order to improve the hydration resistance of lime in the air at room temperature, carbonation and hydration experiments have been conducted. Carbonation of the surface of lime by about 6 wt％ was needed to suppress the hydration of lime used in steel-making. The effect of recirculation of rotary kiln exhaust gas for the carbonation of lime on the combustion temperature and NOx concentration was analyzed by thermodynamics. From the thermodynamic calculation results, it was frond that the equi-librium combustion temperature and NOx concentration decreased with increasing volume percentage of exhaust gas.