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Cho J.-S.,Korea Institute of Limestone and Advanced Materials | Moon K.-Y.,Korea Institute of Limestone and Advanced Materials | Choi M.-K.,Korea Institute of Limestone and Advanced Materials | Cho K.-H.,Korea Institute of Limestone and Advanced Materials | And 2 more authors.
Korean Journal of Chemical Engineering | Year: 2017

Our goal was to verify the manufacturing availability of local Korean natural hydraulic lime (K-NHL) using local Korean low-grade limestone and to test the basic physical properties on the basis of EU standards (BS EN 459-1:2015). We also sought to improve the physical properties of natural hydraulic lime by adding inorganic by-products such as blast furnace slag and silica fume. Where the inorganic by-products were not incorporated, properties such as soundness, air content, particle size, and water absorption (excluding compressive strength and setting time) did not show significant differences with the physical properties evaluated based on EU standards. Also, in terms of the composition of hydraulic phase, local Korean NHL A5 and A8 were similar to NHL 2 of EU standards, whereas local Korean NHL HL correlated with NHL 3.5 or NHL 5. When inorganic by-products were added, the compressive strength and setting time were improved. © 2017 Korean Institute of Chemical Engineers, Seoul, Korea


Moon K.-Y.,Korea Institute of Limestone and Advanced Materials | Choi M.-K.,Korea Institute of Limestone and Advanced Materials | Cho K.-H.,Korea Institute of Limestone and Advanced Materials | Cho J.-S.,Korea Institute of Limestone and Advanced Materials | And 2 more authors.
Journal of the Korean Ceramic Society | Year: 2014

The main mineral phases of natural hydraulic lime (NHL) as a hydraulic lime binderare Ca(OH)2, C2S, C3S, C3A, and SiO2 residues. Also, NHL has the characteristic of setting and hardening by a hydration reaction with water and by carbonation reactions with carbon dioxide from the air. In this study, in an effort to investigate changes of the mineral phases by NHL hydration and carbonation reactions, transitions of mineral phases and the microstructures of hardened pastes were analyzed by XRD, DSC, SEM, and by pore size distributions using domestic and foreign-sourced NHL pastes after curing at 1, 3, 7, and 28 days. On the basis of the analysis results, it was confirmed that domestic low-grade limestone can be used for the manufacturing of NHL. The main hydration mineral phases were Ca(OH)2, CACO3, C2S, and SiO2 residues, while in the case of foreign-sourced NHL, a small amount of an aluminium hydration phase formed. Also, the CACO3 content after the carbonation reaction increased with an increase in the curing time. After hydration for 28 days, NHL containing considerable amounts of C2S and C3S showed higher carbonation ratios than others types.


Cho J.S.,Korea Institute of Limestone and Advanced Materials | Moon K.-Y.,Korea Institute of Limestone and Advanced Materials | Choi M.-K.,Korea Institute of Limestone and Advanced Materials | Cho K.-H.,Korea Institute of Limestone and Advanced Materials | And 2 more authors.
Journal of the Korean Ceramic Society | Year: 2014

Natural hydraulic lime (NHL) is produced by burning a form of low-grade limestone containing silica and alumina which, above certain temperatures, combine with calcium oxide. The resulting silicates and aluminates impart hydraulic properties to the product. This study aims to determine the calcined characteristics of NHL using domestic low-grade limestone with maximized hydraulic properties. Six types of low-grade limestone containing SiO 2 were selected and experiments were carried out with different burning temperatures and holding times. The burning temperature and holding time as the most suitable burning conditions were 1,200°C to 1,300°C and 3 to 7 h, respectively, for the manufacturing of NHL from domestic low-grade limestone. These results demonstrate the feasibility of NHL using domestic low-grade limestone to produce NHL.


Hwang D.J.,Korea Institute of Limestone and Advanced Materials | Hwang D.J.,Chungbuk National University | Ryu J.Y.,Ulimeng Co. | Park J.H.,Ulimeng Co. | And 6 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2013

Mega-crystalline calcite (m-CC) breaks apart easily during calcination, and cannot be easily converted to CaO due to its characteristic that requires massive heat consumption. To solve this problem, the calcination characteristics were compared using electrical furnace (EF) and batch type microwave kiln (BM). After hydrating the manufactured CaO, Ca(OH)2 was produced, and through the carbonation process, CaCO3 was synthesized. The results of the XRD pattern of CaO that was formed through calcinations indicated that decarbonation reaction occurred as 98.2wt.% by EF for 240min, and 97.8wt.% by BM for 30min at the same temperature of 950°C. Hydration results revealed that CaO by EF was high-reactive whereas CaO by BM was medium-reactive. CaCO3 was synthesized through the carbonation process. At 25°C, in both cases, colloidal-shaped CaCO3 was found, and the more spindle-shaped CaCO3 by cubic-shaped self assembly was synthesized at higher temperatures. However, in case of EF, Ca(OH)2 existed in products. © 2013 The Korean Society of Industrial and Engineering Chemistry.


Hwang D.J.,Korea Institute of Limestone and Advanced Materials | Hwang D.J.,Chungbuk National University | Ryu J.Y.,Ulimeng Co. | Park J.H.,Ulimeng Co. | And 5 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2012

Mega-crystalline calcite (m-CC) breaks apart easily during calcination, and is converted to CaO with difficulty due to its thermal decomposing characteristics that necessitate large heat consumption. To overcome this problem, m-CC was calcined using either a microwave furnace or an electric furnace for 15. min and 30. min at 950. °C.Following 15 and 30min calcinations of m-CC, almost all (96.6wt%) and all (100%) of the calcite was calcined to CaO in the microwave furnace, compared to only 11.3wt% and 11.0wt% in the electric furnace, respectively. The excellent conversion rate in the microwave furnace was attributed to its internal heating method. Therefore, calcination of m-CC to CaO was optimized in the microwave furnace at 950°C for 30min. The results demonstrated the potential for the microwave furnace calcination of m-CC, previously known as a non-calcinable material, as a material source for CaO, Ca(OH) 2 and CaCO 3. © 2012 The Korean Society of Industrial and Engineering Chemistry.


Hwang D.J.,Korea Institute of Limestone and Advanced Materials | Yu Y.H.,Korea Institute of Limestone and Advanced Materials | Yu Y.H.,Kwangwoon University | Baek C.S.,Korea Institute of Limestone and Advanced Materials | And 6 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2015

Domestic medium-grade limestone(CaO 53%) is calcined to form CaO for use in steel industries. On the other hand, low-grade limestone(CaO 52%) is directly used for stack-gas desulfurization. In this study, the strongly acidic cation exchange resin (SCR) process was used to obtain high purities.X-ray diffraction results indicated that the calcined product from medium-grade limestone was CaO (98.6wt%) and SiO2 (1.4wt%), and that the product from low-grade limestone was composed of CaO (97.6wt%) and SiO2 (2.4wt%). Hydration reactions revealed 96.7 and 94.0wt% of Ca(OH)2, and the amount of CaCO3 increased because of the reaction of HCO3- in aqueous solutions during the slaking reaction.To prepare precipitated calcium carbonate (PCC, CaCO3), the adsorption of calcium ion and recovery reaction were conducted with the prepared CaO and cation exchange resin(R-SO3H) (1:24kg:kg). High-grade PCC was prepared from the reaction with calcium-adsorbed resin(Ca-(R-SO3)2) and NaOH. Although Ca(OH)2 is amorphous, Ca(OH)2 by calcium adsorption is plate-type and can be used as a plastic filler. Calcium ion was recovered as CaCl2 solution by calcium-adsorbed resin(Ca-(R-SO3)2) and HCl. This solution was concentrated and dried to form CaCl2, which was used to form high-grade PCC, Ca(OH)2, and CaO. © 2015 The Korean Society of Industrial and Engineering Chemistry.


Moon K.-Y.,Korea Institute of Limestone and Advanced Materials | Choi M.-K.,Korea Institute of Limestone and Advanced Materials | Cho J.-S.,Korea Institute of Limestone and Advanced Materials | Cho K.-H.,Korea Institute of Limestone and Advanced Materials | Ahn J.-W.,Korea Institute of Geoscience and Mineral Resources
Journal of the Korean Ceramic Society | Year: 2016

This study aims to produce dolomitic hydraulic lime (D-NHL) using domestic low grade dolomitic limestone and to determine the effect of adding blast furnace slag (BFS) and gypsum as part of an investigation of the hydration properties of D-NHL to increase the mechanical properties. The main mineral phases of D-NHL as a hydraulic lime binder were Ca(OH)2, Mg(OH)2, C2S, C3S, and MgO residues. Ca(OH)2 transformed into CaCO3 in D-NHL paste over the period of 28 days, but the carbonation of Mg(OH)2 and the hydration of C2S did not occur until hydration, after 28 days. Through an investigation of the hydration properties of D-NHL pastes mixed with BFS and gypsum, Al-based compounds such as calcium aluminate hydrates (C4AH13) and ettringite were observed at early hydration time. The compressive strength was improved due to the increased quantities of these hydration products. These results show that good performance results from the application of dolomitic hydraulic lime and that a high value product can be made from domestic waste materials. © 2012 All Right Reserved.


Moon K.-Y.,Korea Institute of Limestone and Advanced Materials | Moon K.-Y.,Korea National University of Transportation | Cho J.-S.,Korea Institute of Limestone and Advanced Materials | Choi M.-K.,Korea Institute of Limestone and Advanced Materials | And 4 more authors.
Journal of Ceramic Processing Research | Year: 2016

Natural hydraulic lime (NHL) has gained a great deal of attention as an eco-friendly construction material, but its application has remained very limited due to its insufficient mechanical properties. The addition of mineral admixture to NHL has been considered as a means of addressing this drawback and improving the mechanical properties for future commercialization. The effects of adding a mineral admixture such as blast furnace slag (BFS) or anhydrite (AH) to NHL on the hydration properties were systematically investigated in this study. Local Korean NHL (K-NHL) was synthesized using domestic lowgrade limestone. The hydration properties of the NHL products were then investigated as a function of the hydration time and the addition ratio of inorganic additives. Through an investigation of the hydration properties of NHL pastes mixed with BFS and AH, Al-based compounds such as calcium aluminate hydrates (C4AH13) and ettringite (3CaO • Al2O3 • 3CaSO4 • 32H2O) were observed at early hydration time. The formation of calcium silicate hydrates (C-S-H) increased with enlargement of the amount of inorganic additives. The compressive strength and setting time were improved due to increased quantities of these hydration products. © 2016, Hanyang University. All rights reserved.


Hwang D.J.,Korea Institute of Limestone and Advanced Materials | Ryu J.Y.,Ulimeng Co. | Yu Y.H.,Korea Institute of Limestone and Advanced Materials | Cho K.H.,Korea Institute of Limestone and Advanced Materials | And 3 more authors.
Journal of Industrial and Engineering Chemistry | Year: 2014

In the conventional kiln, mega-crystalline calcite (m-CC) breaks apart easily during calcinations, and cannot be easily converted to CaO due to that it requiring a lot of heat. In this study, m-CC was calcined to CaO of around 1mm using the rotary microwave kiln. Furthermore, CaCO3 was produced by the carbonation process and hydrothermal process, and the form of CaCO3 was characterized. Calcination of m-CC using the rotary microwave kiln resulted in CaO (97. wt%) of relatively fine size. CaCO3 of colloidal-shaped and 6μm in size could be prepared by applying the carbonation process to Ca(OH)2 using a bubble reactor at 25°C. As the carbonation temperature increased from 25 to 80°C, the shape of prepared CaCO3 changed from a colloidal-type to spindle-type of 1μm due to self-assembly. Also, hexagonal-shaped aragonite could be prepared by the hydrothermal process with the supersaturated Ca(HCO3)2 solutions. © 2013 The Korean Society of Industrial and Engineering Chemistry.


Baek C.-S.,Korea Institute of Limestone and Advanced Materials | Baek C.-S.,Kwangwoon University | Seo J.-H.,Korea Institute of Limestone and Advanced Materials | Cho J.-S.,Korea Institute of Limestone and Advanced Materials | And 2 more authors.
Journal of the Korean Ceramic Society | Year: 2016

Characteristics of wet flue gas desulfurization and in-furnace desulfurization of domestic and overseas limestone with different crystallinity and crystalline size are studied in this article. Properties of desulfurization were evaluated in relation to physicochemical/ mineralogical characteristics, degree of pore formation for different calcination temperatures and TNC(total neutralizing capability). TNC of domestic high crystalline limestone was lower than that of overseas one. On the other hand, the porosity after calcination was shown to be relatively high for domestic limestone, which had high initial rates of desulfurization reactions in-furnace. Based on low pore formation and porosity with high TNC of crystalline high-Ca limestones compared to macrocrystalline ones, the former are preferred for wet desulfurization processes.

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