• 자원리싸이클링
• /
• 제30권6호
• /
• pp.68-75
• /
• 2021

본 연구에서는 석회석, 임의의 산업부산물, 국내산 석탄재 및 시멘트 킬른더스트를 활용해 원료배합특성 및 소성조건에 따른 CCA 특수시멘트 제조특성을 조사하였다. 소성조건에 따른 CCA 특수시멘트 제조특성결과, 소성온도 1200℃에서 CCA 광물상(C₁₂A₇·CaCl₂) 합성량이 최대치를 나타내는 것을 확인할 수 있었다. 소성온도 1300℃에서는 CCA 광물상 합성량이 감소하는 것을 알 수 있었는데, 이는 염소성분 휘발에 의한 현상으로 보여지며, CCA 광물상 합성에 기여했던 CaO-Al₂O₃ 화합물은 SO₃와 결합하여 yeelimite가 형성된 것으로 판단된다. 소성유지시간에 따른 CCA 특수시멘트 제조특성 결과, 대체로 소성시간이 길어짐에 따라 CCA 합성량이 증가하는 경향을 나타내었으나 소성시간 30 min 이상에서는 클링커의 용융현상이 확인되며, 클링커링 공정을 위해서는 소성시간 20 min 이내가 적당한 것으로 사료된다. 이로 미루어볼 때 CCA 특수시멘트 제조를 위한 최적 소성조건은 승온속도 10℃/mim, 소성온도 1200℃, 유지시간 20 min으로 판단되며, 고염소 함유 시멘트 킬른 더스트를 활용한 CCA 특수시멘트 제조가 용이한 것을 알 수 있었다.

• Environmental Engineering Research
• /
• 제14권4호
• /
• pp.212-219
• /
• 2009

Emission characteristics of air pollutants from three commercially operating cement kilns co-burning waste were investigated. The major heavy metals emitted were mercury (Hg), zinc (Zn), nickel (Ni), chromium (Cr), lead (Pb), cadmium (Cd), and arsenic (As) Removal efficiency of the bag filter was above 98.5% for heavy metals (except Hg), and above 60% for Hg. Higher fractions of heavy metals entering the bag filter were speciated to cement kiln dust. On average, 3.3% of the -heavy metals of medium and low toxicity (Pb, Ni, and Cr) entering the bag filter were released into the atmosphere. Among highly toxic heavy metals, 0.14% of Cd, 0.01% of As, and 40% of Hg entering the bag filter were released into the atmosphere. In passing through the bag filter, the proportion of oxidized Hg in all cases increased. Emission variations of hazardous air pollutants in cement kilns tested were related to raw materials, fuel, waste feed and operating conditions. Volatile organic compounds detected in gas emissions were toluene, acrylonitrile benzene, styrene, 1,3-butadiene, and methylene chloride. Although hazardous air pollutants in emissions from cement kilns co-burning waste were within the existing emission limit, efforts are required to minimize their levels.

• 한국건축시공학회지
• /
• 제7권1호
• /
• pp.71-77
• /
• 2007

This paper is to investigate the effect of the curing temperature on strength development of concrete incorporating cement kiln dust(CKD) and blast furnace slag (BS) quantitatively. Estimation of the compressive strength of the concrete was conducted using the equivalent age equation and the rate constant model proposed by Carino. Correction of Carino model was studied to secure the accuracy of strength development estimation by introducing correction factors regarding rate constant and age. An increasing curing temperature results in an increase in strength at early age, but with the elapse of age, strength development at high curing temperature decreases compared with that at low curing temperature. Especially, the use of BS has a remarkable strength development at early age and even at later age, high strength is maintained due to accelerated pozzolanic activity resulting from high temperature. Whereas, at low curing temperature, the use of BS leads to a decrease in compressive strength. Accordingly, much attention should be paid to prevent strength loss at low temperature. Based on the strength development estimation using equivalent age equation, good agreements between measured strength and calculated strength are obtained.

• 한국건축시공학회지
• /
• 제7권2호통권24호
• /
• pp.77-83
• /
• 2007

This study investigated the fundamental properties of the lightweight foamed concrete depending on various admixtures, and the results were summarized as following. When 20% of cement kiln dust(CKD) and 0.002% of stabilizing agent were mixed to lightweight foamed concrete, it was necessary to use a superplasticizer because flowability was decreased. However, it could reduce sinking depth which were the extensive trouble of lightweight foamed concrete. Bulk density was divided into '0.4' and '0.5' grades on KS according to unit volume weight. The compressive strength was less than that of plain concrete when admixtures were applied, but the results exceeded the minimum strength of the each grades on KS. Totally, it is found that the combination of 20% of CKD and 0.002% of stabilizing agent makes it possible to reduce a sinking depth, recycle resources, and save cost when were mixed.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2005년도 추계 학술논문 발표대회
• /
• pp.75-78
• /
• 2005

This raper investigates the effect of curing temperature on strength development of concrete incorporating cement kiln dust(CKD) and blast furnace slag (BS) quantitatively. Estimation of compressive strength of concrete was conducted using equivalent age equation and rate constant model. An increasing curing temperature results in an increase in strength at early age, but with the elapse of age, strength development at high curing temperature decreases compared with that at low curing temperature. Especially, the use of 35 has a remarkable strength development at early age and even at later age, high strength is maintained due to accelerated pozzolanic activity resulting from high temperature. Whereas, at low curing temperature, the use of BS leads to a decrease in compressive strength. Accordingly, much attention should be paid to prevent strength loss at low temperature. Based on the strength development estimation using equivalent age equation, good agreements between measured strength and calculated strength are obtained.

• Advances in nano research
• /
• 제4권3호
• /
• pp.181-195
• /
• 2016

Addition of nano-$SiO_2$ (NS) to geopolymer composites has been studied through measurement of compressive strengths, FTIR and XRD analysis. Alumino-silicate materials are coarse aggregate included waste concrete and demolished walls with its cementing binder, cement kiln dust (CKD) used and can possess a pronouncing activation for the geopolymer reaction resulting from the high alkali contents within. Materials prepared at water/binder ratios in a range of 0.30: 0.40 under curing of $40^{\circ}C$ and 100% Relative Humidity (R.H.), while the used activator is sodium hydroxide in the ratio of 2 wt. %. First, CKD is added in the ratio from 10 up to 50 wt., %, and the demolished walls was varied depending on the used CKD content, while using constant ratio of waste concrete (40 wt., %). Second step, depending on the optimum CKD ratio resulted from the first one (40 wt. %), so the control geopolymer mix composed of cement kiln dust, demolished walls and waste concrete in the ratio (40:20:40, wt %). Nano-silica partially replaced waste concrete by 1 up to 8%. Results indicated that, compressive strengths of geopolymer mixes incorporating nano-silica were obviously higher than those control one, especially at early ages and specially with 3%NS.

• 한국건축시공학회지
• /
• 제9권5호
• /
• pp.119-125
• /
• 2009

본 연구에서는 실무에서 주로 사용되고 있는 FA, 35 및 CKD 치환률에 따른 콘크리트의 기초적 물성 및 건조수축에 미치는 영향을 분석하고 이를 토대로 건조수축 해석을 실시하여 혼화재가 콘크리트의 건조수축에 미치는 영향을 정량적으로 평가하고자 한다. 실험변수로서 혼화재 치환률은 $0{\sim}20%$ 수준으로 결정하였고, W/B는 $40{\sim}50%$의 수준으로 결정하였다. 건조수축해석을 위해 지수함수모델을 적용하였다. 연구결과에 따르면, 혼화재 치환율이 증가함에 따라 유동성 및 공기량이 감소하였으며 초기압축 강도가 저하됨을 확인 하였다. 건조수축 특성으로 혼화재 치환률이 증가함에 따라 건조수축은 증가하는 경향을 보였으며, 건조수축 해석결과 지수함수 모델이 측정치를 양호하게 추정함을 알 수 있었고, 혼화재의 영향을 고려할 필요성이 제기되었다.

• 공업화학
• /
• 제30권6호
• /
• pp.726-730
• /
• 2019

본 연구는 제올라이트를 이용한 칼슘이온 제거에 대한 것으로 시멘트 산업에서 발생하는 cement kiln dust를 이용한 CaCO₃ 제조 공정의 문제를 해결하기 위함이다. 칼슘이온을 제거하기 위하여 제올라이트를 개질하여 사용하였으며 결합 양이온 및 구조를 고려한 최적 제올라이트 선정, 칼슘이온 제거 성능 평가, 개질 용액의 종류 및 농도의 영향, K 공존 시 제거 선택도 평가에 대해 연구를 수행하였다. 5종의 제올라이트 중 13X 제올라이트의 칼슘 이온 제거 성능이 가장 우수함을 확인하였고 NaCl 대신 KCl을 개질 용액으로 사용하였을 때 칼슘이온 제거 성능이 증진되는 것을 확인할 수 있었다. 본 연구는 탄산화 공정의 문제 해결, 고농도의 KCl 회수 기술의 바탕이 될 것으로 판단된다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
• /
• pp.35-38
• /
• 2006

This study investigated fundamental properties of lightweight foamed concrete using cement kiln dust (CKD) and both fly ash(FA) and stability agent. Test results showed that concrete incorporating more amounts of admixture decreased slump flow and it caused increase of superplasiticizer in order to secure the fluidity performance. In addition concrete adding stability agent showed stable flow state, resisting segregation of materials and decreasing bleeding capacity. Sinking depth of concrete incorporating 20% of CKD and adding 0.002% of stability agent was indicated at 0mm. For the properties of hardened concrete. compressive strength of concrete incorporating CKD declined due to a lower appearance density, compared with other specimens. The difference of that was not very significant and the value of ail specimen was higher than KS range. Moreover strength of concrete incorporating CKD was even higher at curing temperature $5^{\circ}C$. Tensile strength ratio of concrete incorporating CKD was indicated between 0.50 to 0.59, which is higher value than control concrete. Heat conductivity of concrete incorporating FA was under the KS range while concrete incorporating 20% of CKD was satisfied in KS. Concrete adding stability agent improved insulation performance due to the lower heat conductivity. In conclusion, it is possible that concrete incorporating 20% of CKD and adding 0.002% of stability agent can secure high quality of lightweight foamed concrete.

• 자원리싸이클링
• /
• 제25권3호
• /
• pp.63-73
• /
• 2016

본 연구에서는 해수로부터 마그네슘을 농축하기 위하여 세 가지 침전제(NaOH, 시멘트 킬른 더스트, 제지슬러지소각재)를 이용하여 마그네슘을 침전시키고, 황산을 이용하여 마그네슘을 용출하는 실험을 진행하였다. 사용한 침전제의 종류와 상관없이 침전반응 효율은 거의 100%이었고, 용출반응 효율은 77 - 89%로 비슷하였다. 용출액의 마그네슘 농도가 4975 - 5775 mg/L이었는데, 이것은 침전반응과 용출반응을 통해 해수의 마그네슘이 3.8 - 4.4배 농축되었음을 의미한다. 본 연구에서 침전제로 사용한 산업부산물의 반응효율은 거의 100%로 기존의 고가 침전제와 비슷하였다.