• Journal of the Korean GEO-environmental Society
• /
• v.20 no.1
• /
• pp.27-33
• /
• 2019

Research was initiated to find out acid drainage neutralizing techniques for ecological vegetative growth on the acid drainage slope. Four different acid drainage neutralizing techniques [no treatment, limestone layer treatment, phosphate treatment, and limestone layer + phosphate treatment] were treated on the acid drainage slope. There was a significant difference observed in treated acid neutralizing techniques for acidity, surface coverage rate, death rate and plant root status. Treated acid neutralizing techniques were effective for neutralizing acidity and vegetative growth in order of [first: limestone layer + phosphate treatment, second: phosphate treatment, third: limestone layer treatment and fourth: no treatment]. The limestone layer and the phosphate treatments were effective for neutralizing acidity and vegetative growth, respectively. However, the phosphate treatment was more effective compared to the limestone layer treatment on the acid drainage slope. We figured out that the phosphate treatment is more effective for neutralizing acidity and vegetative growth because of coating effect of sulfides.

• Resources Recycling
• /
• v.32 no.2
• /
• pp.52-58
• /
• 2023

In this study, soda lime was prepared from slaked lime to expand the scope of limestone use. To evaluate carbon dioxide absorption, an extruder-type and disc-type pelletizers were used to make the soda lime using bentonite as an additive. Regardless of the pelletizing process, the peak of CaCO₃ was confirmed in soda lime due to its reaction with carbon dioxide. Furthermore, it was confirmed that both calcite and aragonite were present together. The soda lime prepared using the disc-type pelletizer showed a larger specific surface area than that prepared using the extruder-type pelletizer did, and the specific surface area improved on adding bentonite. The carbon dioxide absorption rate increased under the sample condition with an enhanced specific surface area.

• The Journal of the Petrological Society of Korea
• /
• v.16 no.2 s.48
• /
• pp.47-58
• /
• 2007

This study examines the distribution of basement rocks in Gyochon-ri, Muan-eup, Muan-gun, Jeonnam where ground subsidence occurred in June 2005, and traces corrosion of limestone. Mica schist and rhyolite are distributed in the surface of the study area, but thick limestone layer with large and small caverns are distributed underground. A horizon of limestone with maximum width of 300 m and 4 km of length was found along the detour which is in the north of pound subsidence. Such identification of limestone presence would be very useful to predict potential ground subsidence. Limestone in this area was disturbed by fold and fault due to severe shearing deformation. Small caverns were frequently found in anticline part of folds formed in limestone layer. Schists with different thicknesses were intercalated in the limestone with shearing deformation and consist of sheet silicate minerals (chlorite and mica) and quartz. In sections of weathered specimen, it is shown that biotite of schist part was altered into chlorite and corrosion of calcite around the schist followed. This suggest that ground water permeated between intercalated sheet silicate minerals and corrosion of limestone began. And small caverns were generated where active corrosion occurred. This study suggests that because of many reasons (for instance, reclamation of the Bulmu reservior and excess pumping), cavern water level was lowered and cave sediments were removed, and it caused ground subsidence to occur.

• Korean Chemical Engineering Research
• /
• v.57 no.5
• /
• pp.743-748
• /
• 2019

This study focuses on the simulation of wet flue gas desulfurization process for improving the production of gypsum by the utilization of low-grade limestone. At present, high-grade limestone with a $CaCO_3$ content of 94% is used for producing merchantable gypsum. In modeling process, a lot of reactions are considered to develop model. First, the limestone dissolution is simulated by RSTOIC model. Second, SOx absorption and crystallization is used by RCSTR model. Finally the gypsum is separated by using SEPERATORS model. Modeling steps make it easy to reflect further side reactions and physical disturbances. In optimization condition, constraints are set to 93% purity of gypsum, 94% desulfurization efficiency, and total use of limestone at 3710 kg/hr. Under these constraints, the mass flow of low-grade limestone was maximized. As a result, the maximum blending quantity of low-grade limestone for 2,100 kg of high-grade limestone that satisfies constraints is about 1,610 kg.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.1
• /
• pp.20-25
• /
• 2021

The cement clinker, the main raw material of cement, is manufactured using limestone as the main material. Depending on the quality of limestone, the use of subsidiary materials changes, and has a great influence on the production of cement clinkers. In this study, the effect of CaO content of limestone, a cement clinker material, on Raw Mill grinding and sintering of cement clinker was investigated. The grinding time of the union materials changed in the content of limestone CaO was measured to identify the grinding properties. The raw material combination was cleaned within a range of 1,350-1,500℃. The sintering performance of cement clinker by Burnability index calculation was identified. The lower the grade of limestone, the lower the grinding quality of the raw material combination. The lower the CaO content of limestone, the greater the variation in F-CaO for sintering temperature. The lower the class of limestone, the higher B. I. value was calculated, indicating the lower cement clinker sintering. In addition, the mineral analysis results of cement clinker showed that if the F-CaO value was low due to the increase in sintering temperature, the Belite content decreased and the Alite content increased. In the case of Alite, the ratio of R-type decreased and that of M-type increased as the content of limestone CaO increased.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.6
• /
• pp.545-551
• /
• 2015

The aim of this research is suggesting application method of the wasted rock obtained from the limestone quarry of raw material for cement as a coarse aggregate for high strength concrete after crushing and sieving processes. The wasted rock has been normally wasted because of its low quality as a material for cement production. In this research, the concrete using this wasted limestone coarse aggregate was evaluated the constructability based on the performances of workability, air content, and compressive strength. From the experiment, a favorable performance was achieved with a limestone coarse aggregate for high strength concrete comparing to the high strength concrete using granite coarse aggregate.

• Journal of Energy Engineering
• /
• v.27 no.3
• /
• pp.48-56
• /
• 2018

The shell waste biomineralization process has known a tremendous metamorphosis and also the nanostructure with the identification of matrix proteins in oyster shells. However, proteins are represented in minor shell components and they are the major macromolecules that control biocrystal synthesis. Aragonite and calcite were derived from molluscan shells and evaluated the source of carbonate minerals and it helps for the formation of limestone. The oyster shell wastes are large and massive. The paleoecological study of oyster beds has discovered a near-shore and thin Upper Rudeis formation with storm influence during the accumulation of oysters with highly altered by disarticulation, bioerosion, and encrustation. It is possible even in the Paleozoic mollusks provided sufficient carbonate entirely to the source of microcrystalline of limestone. The present review is to discuss paleoecologically a number of oyster shell beds accumulated and sediment to form the different types of limestone during the Middle Miocene time.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.10a
• /
• pp.66-75
• /
• 2006

As construction for road tunnel is increasing, various geotechnical conditions can be faced during the construction stage. Especially, if the tunnel is located in limestone area, many kinds of site investigations such as in-situ boring, electrical resistance survey, TSP(Tunnel Seismic Prediction) and etc., are conducted before and during the construction. By conducting these preliminary tests, location, size, and filling materials in limestone cavities can be approximately estimated. Once some cavities which can be harmful for tunnel safety are predicted, methods for ground reinforcement and tunnel excavation, corresponding those ground conditions, have to be established and verified by measurement data and numerical analysis. If necessary, invert lining should be also considered. In this paper, by studying some cases of tunnels constructed in limestone area, predicted problems during construction and rational countermeasures for those are presented.

• Journal of Environmental Health Sciences
• /
• v.23 no.3
• /
• pp.102-108
• /
• 1997

It has been studied that SO$_2$ removal efficiency of anthracite-bituminous coal blend combustion in a fludized bed coal combustor. The objectives of this study were to investigate SO$_2$ removal characteristics of coal blend combustion with Ca/S, anthracite fraction, bed temperature, and limestone size. The experimental results were presented as follows First, the effect of the desulfurization by the dia size of limestone was great and SO$_2$ removal efficiency was highest in limestone dia 631 $\mu$m. Second, as air velocity increased, the desulfurization rate decreased a little. But the difference of the desulfurization rate according to air velocity was not too large. As the height of fluidized bed combustor increased regardless of air velocity, SO$_2$ concentration tends to increase largely. Third, as Ca/S mole ratio incresed, SO$_2$ desulfurization rate incresed rapidly up to Ca/S mole ratio 3 while the desulfurization rates did not increse too largely in the range of more than the level. Forth, the bed temperature had a great effect on the desulfurization rate and the desulfurization rate tended to increase slightly as anthracite fraction increased.

• Journal of the Korean Ceramic Society
• /
• v.52 no.6
• /
• pp.479-482
• /
• 2015

The flue gas desulfurization (FGD) process is one of the most effective methods to reduce the amount of $SO_2$ gas (up to 90%) generated by the use of fossil fuel. Limestone is usually used as a desulfurizing agent in the wet-type FGD process; however, the limestone reserves of domestic mines have become exhausted. In this study, limestone sludge produced from the steel works process is used as a desulfurizing agent. Seven different types of additives are also used to improve the efficiency of the desulfurization process. As a result, alkaline additive is identified as the least effective additive, while certain types of organic acids show higher efficiency. It is also observed that the amount of FGD gypsum, which is a by-product of the FGD process, increases with the used of some of those additives.