Modeling of the wet flue gas desulfurization system to utilize low-grade limestone

임종훈,최영렬,김건열,김정환 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.12

Wet flue gas desulfurization was simulated to improve gypsum production using low-grade limestone. High-grade limestone with 94 wt% CaCO3 content is used for producing gypsum with 93 wt% purity, but owing to the resource depletion of high-grade limestone, low-grade limestone should be replaced as an alternative. However, lowgrade limestone with CaCO3 purity of less than 94% contains impurities such as MgCO3, Al2O3, and SiO2, which reduce gypsum purity. To resolve this issue, a process involving mixing of both low-grade and high-grade limestone was simulated to predict the quantity of low-grade limestone that could be utilized. Many reactions like limestone dissolution, SOX absorption, and crystallization were considered and were simulated by different models in Aspen plus. For process optimization, the following constraints were set: 93 wt% gypsum purity, 94% desulfurization efficiency, and 3,710 kg/h total limestone usage, which maximized the mass flow of low-grade limestone. The maximum blending quantity of low-grade limestone for 2,100 kg high-grade limestone that satisfied the constraints was ~1,610 kg.

정선-삼척 일대 대기층 상부 고품위 석회석의 생성환경

김창성(Chang Seong Kim),최선규(Seon-Gyu Cho),김규보(Gyu-Bo Kim),강정극(Jeonggeuk Kang),김경배(Kyeong Bae Kim),김학수(Hagsoo Kim),이정상(Jeongsang Lee),유인창(In-Chang Ryu) 대한자원환경지질학회 2017 자원환경지질 Vol.50 No.4

대기층의 고품위 석회석 생성기작은 고품위로 퇴적되었다는 견해와 퇴적 이후 열수의 작용에 의해 상부 영역에 국한되어 백색화와 함께 고품위화 하였다는 두 가지 견해로 나뉘어 있으며, 광물-암석화학적 연구를 통해 이들 견해를 검토하였다. 대기층의 암색은 크게 백색, 담갈색, 담회색, 회색, 암회색의 다섯 단계로 구분할 수 있다. 이 중 백색~ 담회색 암석은 53.15 ~ 55.64 wt. % CaO의 고품위 석회석이며, 담갈색은 20.71 ~ 21.67 wt. % MgO로 거의 순수한 백운석이다. 대기층은 상부와 하부의 석회암대와 그 사이에 중부 백운암대로 구성되어 있으며, 상부가 하부에 비해 전반적으로 높은 CaO 함량을 보인다. 다만, 대기층 상부와 하부에서 전반적으로 백색화 현상이 관찰되며, 하부 에서 백색에 비해 담회색 암석의 CaO 함량이 높은 경향이 나타나고 있어, 백색화와 CaO 함량은 상관관계가 없는 것으로 확인된다. 또한, 고품위 석회석과 중-저품위 석회석의 구분은 CaO 성분과 함께 Al 2 O 3 , K 2 O 등 이질성분의 함유 정도에 따라 구분되는데, 백색도가 높은 영역에서 이질성분의 함량이 증가하는 양상을 보이기도 한다. 특히, Al 2 O 3 는열수에 의해 쉽게 제거될 수 없는 성분이므로, 열수 작용에 의해 백색화와 함께 이질 성분이 제거되었다는 이론은 증거가 미약한 것으로 판단된다. 산소-탄소 안정동위원소 분포는 대기층 상부와 하부의 석회암대 모두에서 탄소 안정동 위원소의 변화 폭은 2 ‰ 이내인 반면, 산소 안정동위원소는 16 ‰ 이상의 큰 폭의 변화가 인지되어, 대기층 전반 적으로 열수의 영향을 받은 것으로 확인된다. 열수작용의 시기는 85.1 ± 1.7 Ma로 주변 동원광산의 광화시기와 일치한다. 회색-담회색-백색으로 백색화가 진행될수록 산소 안정동위원소 비는 낮아지는 경향이 확인되며, 이는 이 지역 탄산염암의 백색화는 열수에 의한 현상임을 지시한다. 따라서, 대기층은 전반적으로 열수의 영향을 받았으며, 열수에 의해 백색화가 진행되었으나, 고품위 석회석화는 백색화와 관련이 없으며, 열수에 의한 현상이 아닌 것으로 판단된다 . 대기층 상부에서의 고품위화는 이질물 특히, Al 2 O 3 성분이 효과적으로 제거될 수 있는 퇴적환경을 고려하여야 하며 , 중부 백운암대를 중심으로 상-하부 주변에서 CaO 함량이 증가하는 양상으로부터 순차층서적으로 퇴적 당시 이질물의 퇴적작용이 배제된 탄산염 천해환경이 조성된 결과로 보는 것이 타당할 것이다. The carbonate rocks of the Daegi Formation are composed of the limestone at the upper and lower zones, and the dolomite at the middle zone, in which the upper zone has higher CaO content than others. The colors of carbonate rock in the Daegi Formation can be divided into five types; white, light brown, light grey, grey, and dark grey. The white to light grey colored rocks correspond to the high purity limestone with 53.15 ~ 55.64 wt. % CaO, and the light brown colored rocks contain 20.71 ~ 21.67 wt. % MgO. The bleaching of carbonate rocks are not related to CaO composition of the rocks, as light grey rocks tend to be higher in CaO content than those of the white rocks at the lower zone. The pelitic components are also occasionally increased in white limestone than light grey one. Al 2 O 3 is one of the most difficult content to remove during hydrothermal processes, so the interpretation that the limestone is purified together with hydrothemral bleaching, has little merit. The wide range (over 16 ‰) of δ 18 O SMOW , smaller variation (within 2 ‰) of δ 13 C PDB are apparent in both the upper and lower zones, which indicate the Daegi Formation had been affected overall by hydrothermal fluids. The K-Ar isotopic age of hydrothermal alteration in the GMI limestone mine is 85.1 ± 1.7 Ma. Gradual change from grey through light grey to white limestone is accompanied by lower oxygen stable isotope values, which is major evidence that the hydrothermal effect is the main process of the bleaching. Although the Daegi Formation has suffered from hydrothermal activity and increase in whiteness, there is no clear evidence demonstrating the relationship between bleaching and high purity of limestone. The purification of limestone has nothing to do with the hydrothermal activity in this area. Instead, it should be considered that the change of sedimentary environment related to see-level fluctuation which can prevent deposition of pelitic components especially Al 2 O 3 contrbuted to the formation of the high purity limestone in the upper zone of the Daegi Formation. Considering the evidences such as increase in CaO content of limestone by depth, gradual change from calcite to dolomite at the lower zones, and occurring the high purity limestone at the upper zone, the interpretation of sequence stratigraphic aspect to the formation of the high purity Daegi limestone appears to be more suitable than that of hydrothermal alteration origin.

A Brief Review on Limestone Sources and Oyster Waste Generation-Bantayan

Yu, Kwang Sun,Thriveni, Thenepalli,Jegal, Yujin,Whan, Ahn Ji The Korean Society for Energy 2017 에너지공학 Vol.26 No.1

Limestone is an important commodity in Philippines. Limestone has numerous uses that range from agricultural applications to building materials to medicines. Many limestone products require rock with specific physical and chemical characteristics. Most limestone is biochemical in origin meaning the calcium carbonate in the stone originated from shelled oceanic creatures. In this paper, we reported the natural sources of limestone, geological formation of limestone and the oyster shell waste in Cebu, Bantayan, Philippines were reported. Due to the mining or quarrying in Cebu, Bantayan, in a limestone area poses the threat of groundwater pollution (since limestone is a porous geologic formation with a high transmissivity). The other environmental issue is oyster shell waste. The oyster shell waste is the major source of limestone. We developed and applied appropriate technologies for the extraction of limestone from oyster shell waste and utilizes as high value added material.

An Exploratory Research on PCC Application of Crystalline Limestone: Effects of Limestone Crystallographic Characteristicson Hydraulic Activity

Yang, Ye-Jin,Jegal, Yu-Jin,Nam, Seong-Young,Kim, Jin,Ahn, Ji-Whan The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.2

Quicklime(CaO) is generally obtained through the calcination of limestone, the main component of which is calcium carbonate($CaCO_3$). Quicklime generates high-temperature heat when reacting with water, forming slaked lime($Ca(OH)_2$). The industrial sectors for limestone are determined by the hydraulic activity of slaked lime, which is obtained by measuring temperature changes during the hydration reaction. Accordingly, this study examined the different crystallographic characteristics of limestone as affected by the geological origins of the regions where the limestones were produced, and how these characteristics affected hydraulic activity. Six limestone samples were collected from the Jecheon and Cheongsong areas and the hydraulic activities were measured in accordance with KS E 3077. The results indicate that limestone produced in the Cheongsong area, recrystallized through metamorphism caused by hydrothermal alteration, hada larger grain size of calcite than that of the Jecheon area, and displays a tendency of changing to marble. Limestone from the Cheonsong area showed more radical reaction in the early stage of hydration compared to that ofthe Jecheon area. In addition, it was revealed that limestone having more impurities like $SiO_2$ have lower hydraulic activity.

보통 포틀랜드 시멘트 페이스트의 유동특성에 미치는 석회석 미분말의 영향

이승헌,박정수,이정인,조재우 한국세라믹학회 2013 한국세라믹학회지 Vol.50 No.2

This study examines the effects of limestone’s factors on the fluidity of cement paste when of up to 15%. As the substitution ratio of limestone powder increases, the fluidity of the paste is also improved; however, it has no correlation to the CaCO3 content of the limestone, fineness of the limestone, and fluidity of the pastes. Regardless of clay content of the limestone, it showed a similar mini-slump, so there was no correlation between the clay content and the fluidity of the paste. Also, the total organic carbon content of the limestone and the fluidity of the paste showed no correlation. Regardless of the limestone’s grade or fineness, n value of powder gained by using the Rosin-Rammler distribution function showed that the fluidity of the paste increased as the n value reduced. It was also shown that particle size distribution of ordinary Portland cement with limestone powder had a major effect on the fluidity of the paste.

Limestone Related Problems for Foundations in Central Vietnam

( Tomohiro Yasuda ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

We conducted geological reconnaissance and exploratory drilling for a candidate plant site in Central Vietnam. The geological investigation reveals that the site is underlain by limestone. We identified typical limestone features, namely cavity, sinkhole, slump zone and Karst topography. It is concerned that foundation pressure may overstress cavities and cause collapse of cavities. That would result in new sinkhole or ground settlement, which may damage surrounding structures and buildings. Slump zones were observed below very stiff/dense overlying soils and immediately above limestone, where soils were very loose with SPT N-values of 5 or less. It is possible that slump zone expands by flowing loose soils into underlying cavities. The spread slump zone may cause sinkholes. Karst topography with depths varying from 40 to 70 metres is likely to cause several problems for pile foundation. Where piles are driven to the top of limestone, the pile lengths drastically vary in a short distance. When the piles are driven onto steeply inclined limestone surface and deep ditches, the piles can be damaged. Additionally, if the pile is supported on an overhang, its bearing capacity might be insufficient. To overcome limestone related problems, cavity probing and grout treatment for cavity and slump zone are required for proposed shallow and pile foundations. However, the probing and treatment are costly and time consuming. As the thorough probing and treatment are practically impossible, unexpected sinkhole or settlement remains unavoidable even after the probing and treatment. Consequently, we recommended relocating the site to avoid the limestone area.

Analysis of hydration and strength optimization of cement-fly ash-limestone ternary blended concrete

Elsevier 2018 Construction and Building Materials Vol.166 No.-

<P><B>Abstract</B></P> <P>Limestone powder improves concrete early-age strength while fly ash improves concrete late-age strength due to its pozzolanic reaction. The optimal mixture of cement, fly ash, and limestone is crucial for material design of ternary blended concrete. This research presents a simulation program for evaluating the hydration and strength optimization of ternary blended concrete. The simulation program begins with a kinetic hydration model which simulates the hydration of cement-fly ash-limestone ternary blends. The hydration model considers the mutual effects among reactions of cement, fly ash, and limestone by means of the contents of calcium hydroxide and capillary water. The individual reaction degrees of components of ternary blends are calculated from the hydration model. Furthermore, the compressive strength growth of hydrating ternary blended concrete is calculated by means of gel-space ratio and Powers’ strength theory. Finally, based on parameter studies, the optimal combinations of cement, fly ash, and limestone at different ages are determined. The proposed numerical procedure is valuable for making composite cements as it pertains to compressive strength and environment regulations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Simulate the hydration of cement-fly ash-limestone ternary blends. </LI> <LI> Consider interactions among cement hydration, fly ash reaction, and limestone reaction. </LI> <LI> Evaluate the strength development of ternary blended concrete. </LI> <LI> Find the optimum combinations of cement, fly ash, and limestone. </LI> </UL> </P>

Impacts of Limestone Multi-particle Size on Production Performance, Egg Shell Quality, and Egg Quality in Laying Hens

Guo, X.Y.,Kim, I.H. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.6

This experiment was conducted to evaluate the effects of single or multi-particle size limestone on the egg shell quality, egg production, egg quality and feed intake in laying hens. A total of 280 laying hens (ISA brown) were used in this 10-wk trial. Laying hens were randomly assigned to 4 treatments with 14 replications per treatment and 5 adjacent cages as a replication (hens were caged individually). The experimental treatments were: i) L, basal diet+10% large particle limestone; ii) LS1, basal diet+8% large particle limestone+2% small particle limestone; iii) LS2, basal diet+6% large particle limestone+4% small particle limestone; iv) S, basal diet+10% small particle limestone. The egg production was unaffected by dietary treatments. The egg weight in S treatment was lighter than other treatments (p<0.05). The egg specific gravity in S treatment was lower than other treatments (p<0.05). The eggshell strength and eggshell thickness in S treatment were decreased when compared with other dietary treatments (p<0.05). The laying hens in LS1 and LS2 treatment had a higher average feed intake than the other two treatments (p<0.05). Collectively,the dietary multi-particle size limestone supplementation could be as efficient as large particle size limestone.

환원반응조에서 회수한 석회석의 알칼리도 생성 및 중화특성

정영욱,임길재,박현성 한국자원공학회 2011 한국자원공학회지 Vol.48 No.4

A study was carried out to evaluate the remaining alkalinity producing capacities and reuse potential of the used limestone from successive alkalinity producing systems (SAPS) when limestone would be excavated to ameliorate. With two reactors having limestones and cow manure as substrates and mine waters as reacting medium anoxic environment was created in the plastic containers, in the laboratory. The limestone was retrieved for comparison of its alkalinity production potential. When the limestone samples retrieved from reactors, redox potential was lowered below -300 mV, dissolved oxygen reduced to less than 1 mg/L, alkalinity reached 1500 mg/L CaCO_3 or more. The limestone from the reactor with higher acidic mine water produced about a 300 mg/L CaCO_3 of alkalinity while the one less acidic produced around a 130 mg/L CaCO_3. After washing both the limestone samples, it was observed that these still produced alkalinity of about 100 mg/L CaCO_3, though less than the 130 mg/L CaCO_3 of the fresh limestone. It meant that the limestones that are removed when repairing SAPSs on sites, could be reused. 연구의 목적은 현장 Successive alkalinity producing system 조를 보수할 때 굴착되는 석회석의 재이용 가능성을 평가하는 것이었다. 실내에서 석회석, 우분 및 광산배수가 포함된 반응조를 조성한 후 환원환경으로 변했을 때 석회석을 회수하여 알칼리도 생성과 중화 능력을 평가 하였다. 회수시 반응조 수질은 EC -300 mV 미만, DO는 1 mg/L 이하, 알칼리도는 1,500 mg/L CaCO_3 이상이었다. 산도가 높은 광산배수에서 회수된 석회석은 약 300 mg/L CaCO_3 알칼리도를 생성한 반면 산도가 낮은 석회석은 약 130 mg/L CaCO_3 전후의 알칼리도를 생성 하였다. 이들 석회석을 세척한 결과 모두 약 100 mg/L CaCO_3 의 알칼리도를 나타냈다. 따라서 환원상태로 있는 현장 SAPS 조의 석회석 경우 재이용 가능성이 있을 것으로 판단되었다.

조선시대 조적용 석회의 소성 성능과 모르타르의 물성에 대한 실험 연구

이상옥,정광용 한국건축역사학회 2016 건축역사연구 Vol.25 No.3

This study was to investigate the firing method of limestone in Joseon Dynasty, and analyze the physical·chemical properties of lime mortars in Joseon Dynasty. This study was to manufacture and evaluate the firing experiment and mortar of Limestone by each sort in order to reproduce the traditional lime mortars in Joseon Dynasty, and investigate the behavior to improve physical properties according to the firing method of Limestone. This study has found out that there were screening criteria and standard of appropriate firing temperature about the Limestone in Joseon Dynasty. Accordingly, this study was to improve its strength through various additives and mixture. In particular, in case of Limestone, the black and blue Limestone were preferred, and most of domestic Limestones were low grade Limestone including the clay and took ivory white or blue with low whiteness. This study has shown that the low grade Limestone was mined by the surface mining compared with the high grade Limestone as underground mining method, and could be used because it was easy to mine relatively and there was possibility that Natural Hydraulic Lime(NHL) was used with the traditional lime mortars in Joseon Dynasty. 본 연구에서는 조선시대 전통 灰의 제작기술을 조사하고, 조선시대 석회 모르타르에 대한 물리적·화학적 특성을 분석하였다. 조선시대 전통 灰를 재현하기 위한 종류별 석회석의 소성실험과 모르타르 제작평가를 하였으며, 석회석 소성방법에 따른 물리적 특성 향상 거동을 규명하였다. 조선시대에는 석회석에 대한 선별기준과 적정 소성온도 기준이 있었으며, 여러 첨가물과 배합방법을 통하여 강도를 개선하고자 하였음을 알 수 있다. 특히 석회석의 경우 흑색과 청색 석회석을 선호하였으며, 국내의 석회석은 점토질을 함유한 저품위 석회석이 대부분이고 백색도가 낮은 유백색 또는 청색을 띠고 있다. 저품위 석회석은 갱내채광인 고품위 석회석에 비하여 노천채광으로 채광되며 상대적으로 채광이 용이하기 때문에 이를 사용하였음을 알 수 있으며, 조선시대 전통 灰로 천연 수경성 석회(NHL)가 사용되었을 가능성을 확인할 수 있었다.