Recycling of dust wastes as lightweight aggregates

김유택,J.H. Kim,K.G. Lee,강승구 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.2

Various kinds of industrial dust wastes were recycled by a wet ceramic process. Compounding various dusts gave allowed us compositional variation of dust wastes which originated from various places and conditions. One of the main problems for recycling wastes is caused by compositional variations. Success in recycling depends on how to control compositions and maintain the allowed purity level in the wastes. Grouping of dust wastes into three categories and compounding were introduced to raw material preparation processes for the successful recycling of various dusts. Pretreatment processes were also important to stabilize heavy metals in the raw materials. These processes consist of ion exchange, control of electrolyte concentration and pH etc. After these processes, industrial dust wastes were turned into safe, ecological construction materials such as bricks or lightweight aggregates by a final sintering process. Various kinds of industrial dust wastes were recycled by a wet ceramic process. Compounding various dusts gave allowed us compositional variation of dust wastes which originated from various places and conditions. One of the main problems for recycling wastes is caused by compositional variations. Success in recycling depends on how to control compositions and maintain the allowed purity level in the wastes. Grouping of dust wastes into three categories and compounding were introduced to raw material preparation processes for the successful recycling of various dusts. Pretreatment processes were also important to stabilize heavy metals in the raw materials. These processes consist of ion exchange, control of electrolyte concentration and pH etc. After these processes, industrial dust wastes were turned into safe, ecological construction materials such as bricks or lightweight aggregates by a final sintering process.

졸겔법으로 제조한 ErMnO₃ 박막의 강유전 특성

김유택,김응수,채정훈,류재호,Kim, Yoo-Taek,Kim, Eung-Soo,Chae, Jung-Hoon,Ryu, Jae-Ho 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.9

$Er(NO_3)_3{\codt}5H_2O,\;Mn(CH_3CO_2)_2{\cdot}4H_2O$를 출발원료로 사용하여 졸-겔 법으로 Si(100) 기판 위에 코팅된 $ErMnO_3$ 박막의 강유전 특성에 관하여 연구하였다. $ErMnO_3$ 박막은 800$^{\circ}C$에서 결정화가 시작되었으며, (001)로 우선 배향된 $ErMnO_3$ 박막을 얻을 수 있었다. 본 실험에서 800$^{\circ}C$에서 1 h 열처리하여 얻은 $ErMnO_3$ 박막은 1∼100 KHz의 주파수 범위에서 유전 상수(k)는 26, 유전 손실(tan ${\delta}$)은 0.032의 값을 나타내었으며, 이때 $ErMnO_3$ 박막의 입자 크기는 10∼30 nm이었다. 강유전 특성은 (001) 배향성이 증가할수록 잔류 분극 값이 증가하였으며, 800$^{\circ}C$에서 1시간 열처리하여 $ErMnO_3$ 박막의 잔류 분극 값($P_r$)은 400 nC/$cm^2$를 나타내었다. 또한 열처리 시간이 증가할수록 치밀하고 균일한 박막을 얻어 낮은 항전계 ($E_c$) 값을 가졌다. Ferroelectric properties of $ErMnO_3$ thin films deposited on Si(100) substrate using Sol-gel process with metal salts were investigated. $ErMnO_3$ thin films with a (001) preferred orientation were crystallized at 800$^{\circ}C$. The $ErMnO_3$ thin film post-annealed at 800$^{\circ}C$ for 1 h showed the dielectric constant(k) of 26 and the dielectric loss(tan ${\delta}$) of 0.032 at the frequency range from 1 to 100 KHz. The grain size of $ErMnO_3$ thin film post-annealed at 800 for 1 h was 10∼30 nm. The remanent polarization($P_r$) of the $ErMnO_3$ thin films increased with increasing (001) preferred orientation. The $ErMnO_3$ thin films post-annealed at 800$^{\circ}C$ for 1 h showed the remanent polarization($P_r$) of 400 nC/$cm^2$, with the increase of post-annealing time at 800$^{\circ}C$, the coercive field($E_c$) of thin films was lowered because the dense and homogeneous thin films were obtained.

Adsorption behavior of heavy metal ions in the solutions of clay minerals under various conditions

김유택,J.H. Kim,K.G. Lee,강승구 한양대학교 세라믹연구소 2005 Journal of Ceramic Processing Research Vol.6 No.1

The adsorption rates and characteristics of heavy metal ions (Cd, Cr, and Zn) were examined with solutions mixed with red clay, white clay, a mixture of red & white clay and zeolite under various pHs and initial concentrations. As expected, adsorption rates of heavy metal ions generally increased with increasing pH; however, Cr showed a particular behavior. A mixture of red & white clay among the clay minerals tried in this study showed the highest Cr adsorption rate at the low pH conditions (lower than pH 5) and red clay with additions of Cu, Fe and Pb ions at pH 5 showed above an 85% adsorption rate of Cr which was far from expectations. From the result, it is concluded that the adsorption characteristics of heavy metal ions depend not only on the physical properties of the absorbent itself such as the cation exchange capacity (CEC) but also on the concentration and existence of exchangeable cations, pH, ligands, etc.. The adsorption rates and characteristics of heavy metal ions (Cd, Cr, and Zn) were examined with solutions mixed with red clay, white clay, a mixture of red & white clay and zeolite under various pHs and initial concentrations. As expected, adsorption rates of heavy metal ions generally increased with increasing pH; however, Cr showed a particular behavior. A mixture of red & white clay among the clay minerals tried in this study showed the highest Cr adsorption rate at the low pH conditions (lower than pH 5) and red clay with additions of Cu, Fe and Pb ions at pH 5 showed above an 85% adsorption rate of Cr which was far from expectations. From the result, it is concluded that the adsorption characteristics of heavy metal ions depend not only on the physical properties of the absorbent itself such as the cation exchange capacity (CEC) but also on the concentration and existence of exchangeable cations, pH, ligands, etc..

소형 스크류식 원심펌프의 기액 이상류 특성

김유택,다나카카즈히로,이영호,Kim, You-Taek,Tanaka, Kazuhiro,Lee, Young-Ho 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.4

A screw-type centrifugal pump was manufactured to carry primarily solids and its impeller had a wide flow passage. However, there was an effect on the flow passage shape on delay of the choke due to entrained air not being clarified yet. Moreover, because its impeller has a particular shape, only few studies have tried to clarify the pump performance and details of internal flow pattern of that pump. For this reason, we carried out the pump performance experiment under air-water two-phase flow condition with different impeller tip clearances, pump rotational speeds and void fractions by using a small screw-type centrifugal pump designed to acquire basic data. In a general centrifugal pump, it was reported that there was a loss of pump head from single-phase flow to the choke due to air entrainment near the best efficiency point being large. However, the loss near the best efficient point in a screw-type centrifugal pump became less than that in a general centrifugal pump.

기액 이상류시의 스크류식 원심펌프의 압력분포

김유택,최민선,이영호,Kim, You-Taek,Choi, Min-Seon,Lee, Young-Ho 한국유체기계학회 2001 한국유체기계학회 논문집 Vol.4 No.3

It is reported recently that the pump head deterioration near the best efficiency point, from single-phase flow to the choke due to air entrainment became less in a screw-type centrifugal pump than in a general centrifugal pump. Moreover, at a narrow tip clearance, the pump head became partially higher in two-phase flow than that in single-phase flow. However, the internal pressure fluctuations on this pump due to air entrainment have not been studied yet. For that reason, we have examined the influences of void fraction, flow coefficient and impeller tip clearance on pressure fluctuations in the casing. The void fraction became larger, the influence of tip clearance on pressure distribution became less.

경제개발(經濟開發) 5개년계획(個年計劃)을 성공(咸功)시키는 길

김유택,Kim, Yu-Taek 한국과학기술정보연구원 과학기술정보센터 1963 Journal of Information Science Theory and Practice Vol.1 No.1

강제대류계(强制對流系)에 있어서 막비등열전달(膜沸騰熱傳達)에 관한 연구(硏究)

김유택,권순석,정대인,Kim, Y.T.,Kwon, S.S.,Jung, D.I. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.1

The aim of this study is to investigate the heat transfer characteristics in the transient cooling process of a high temperature wall. The slow transient cooling experiment was carried out with a copper block of high thermal capacity. The results of these experiments are as follows. 1. Temperature histories measured by the thermocouple, which is 0.99, 2.00, 2.99mm from the heat transfer surface showed monotonous during the cooling process. These variation are the curves of typical temperature histories in film-boiling, transition-boiling, and nucleate-boiling regions. 2. The temperature histories were measured by thermocouple installed in the copper block. The variations of the surface heat fluxes and surface temperature were computed from the numerical solution method TDMA from the measured temperature histories for radial position one dimensional heat transfer inverse problem. The boiling curves were found by the computed temperature histories. 3. The rewetting point which starts to change from film boiling to nucleate boiling is not connected with the mass velocity and it were found that the temperature of rewetting point indicated about $100^{\circ}C$. 4. The heat flux of rewetting point was about $10^5Kcal/m^2h$, at that time, the heat transfer coeficient indicated about $1000Kcal/m^2h^{\circ}C$ irrelevent to mass velocity. 5. The wall superheat decreases as the pressure increases. But I found that rewetting point appeared under higher condition in the wall temperature.

프리웨팅된 인공경량골재의 흡수 특성

김유택,장창섭,류유광,Kim, Yoo-Taek,Jang, Chang-Sub,Ryu, Yug-Wang 한국결정성장학회 2011 한국결정성장학회지 Vol.21 No.2

인공경량 골재는 다결정질 소성체를 주 구성으로 하므로 골재 내부에 다량의 공극이 일정비율로 형성되는 것이 특징이다. 이러한 인공경량 골재는 조직 구조의 특성상 외부환경의 변화에 의해 수분이 비정상적인 이동을 보이는 경향이 있다. 다공질 재료의 수분 방출 특성은 일반적으로 기공률 및 기공크기 분포에 크게 좌우되지만, 인공적으로 소결 제조된 경우에는 표면에 생성된 치밀한 구조의 표피층에도 많은 영향을 받을 것으로 생각된다. 인공경량 골재 내부의 수분 이동에 미치는 요인은 골재내의 세공 및 공극의 분포와 형상, 크기, 그리고 프리웨팅 방법 등이 있으며 각 조건에 따라 상당한 차이를 보인다. 본 연구에서는 인공경량 골재를 제조하여 골재의 가압시 흡수 특성이나 침수시간에 대한 흡수율의 거동에 대한 명확한 규명을 함으로써 경량골재 펌프압송을 위한 기초적 자료를 제공하고자 하였다. 본 실험에 사용된 인공경량골재는 독일 'L'사의 상업용 인공경량골재와 본 연구팀이 제조한 2가지 조성의 인공경량골재를 사용하였으며, 골재 수분함침시간, 진공압력, 급냉조건을 변화시켜 골재의 흡수율을 측정하였다. 인공경량골재를 $300^{\circ}C$ 에서 급냉 하였을 경우 24시간 침수보다 높은 흡수율을 보였고, 진공압력에 따라 흡수율이 증가하는 경향이 있으며, -300 mmHg의 진공 압력시 24시간 침수보다 "L"사 골재는 54 %의 높은 증가를 보였으나 K622와 K73 골재는 비교적 적은 2 % 내외의 흡수율 증가양상을 보였다. Lightweight aggregate which is composed of sintered polycrystalline materials usually has a certain portion of pores inside of it. Because of such a structural characteristics, it tends to that movement of water in aggregate shows an abnormal behavior against the change of outside environment. In general, water movement behavior is controlled by porosity, distribution of pore size; however, dense surface layer will also affect water movement behavior in case of artificially sintered aggregates. Factors affecting water movement behavior in the aggregate are pore distribution, pore shape, pre-wetting method, etc. In this study, absorption characteristics of aggregate under the pressure and absorption rate according to water dipping time are analyzed for the basis of pressure pumping of lightweight concrete. Two kinds of aggregates were used for the test: one is made by 'L' company in Germany and the other is of our own made at the pilot plant in Kyonggi University. Absorption rate of aggregate is measured according to water dipping time, vacuum pressure, and quenching condition. Absorption rate of aggregate with $300^{\circ}C$ quenching is higher than that of aggregate with 24 hr water dipping. Generally the more vacuum the higher water absorption rate. Water absorption rate of 'L' aggregate under -300 mmHg is 54 % higher than that of aggregate with 24 hr water dipping; however, only 2 % increase in water absorption was measured for the K622 and K73 which were of our own.

공정조건 변화에 따른 탄산화 녹색건자재의 물성

김유택,Kim, Yootaek 한국결정성장학회 2013 한국결정성장학회지 Vol.23 No.3

발전소에서 발생되는 산업부산물인 석탄재는 포집방법에 따라 크게 저회와 비산회로 구분되는데, 순환유동층 연소방식에서 발생되는 비산회는 탄산화 반응 인자인 Ca 성분을 다량 포함하고 있다. 탄산화 반응 인자가 풍부한 비산회를 시멘트에 일정량 치환하여 제조한 경화체를 초임계 이산화탄소($CO_2$) 분위기조건에서 반응시켜 제작된 경화체의 기계적 물성향상을 도모하였다. 시멘트 대비 비산회 치환량을 10~40 %까지 10 % 단위로 4수준으로 하여 경화체를 제작하였으며 각각 3, 14, 28일 동안 양생하여 각 양생일 마다 탄산화를 진행하였으며 공정조건 변수로 탄산화 시 발생되는 수분과 미수화 반응물의 추가적인 포졸란 반응을 유도하기 위하여 탄산화 후 7일 동안 추가양생을 실시하였다. 공정조건의 변화를 변수로 둔 경화체의 무게변화율, TG/DTA 분석, 1 % 페놀프탈레인 알칼리성 측정을 통하여 탄산화 진행여부를 확인하였으며, 경화체의 압축강도 측정을 통해 기계적 물성향상을 분석하였다. 임계 탄산화 후 7일간 추가 양생시킨 녹색 건자재의 기계적 물성은 추가 양생하지 않은 시편과 비교해 44 % 향상되었다. The purpose of this study is to enhance the mechanical strength of specimens containing fly ash from fluidized bed type boiler, which the recycling rate will be eventually increased. Specimens containing fly ash in a certain portion were made and aged for 3, 14, and 28 days. Specimens were carbonated under the supercritical condition at $40^{\circ}C$. The carbonation process under the supercritical condition was performed to enhance the mechanical property of specimens by filling the voids and cracks existing inside cement specimen with $CaCO_3$ reactants. The additional aging effect after the supercritical carbonation process on mechanical strength of specimens was also investigated by comparing the compressive strength with and without 7 day extra aging. Under the supercritical condition and additional 7 day aging specimens were very effective for enhancement of mechanical strength and compressive strength increased by 44 %.

재활용 폐자원에 따른 지오폴리머의 특성변화 연구

김유택,김현정,장창섭,Kim, Yoo-Teak,Kim, Hyun-Jung,Jang, Chang-Sub 한국결정성장학회 2012 한국결정성장학회지 Vol.22 No.3

본 연구는 알칼리 활성화제로 NaOH와 물유리를 사용하고 리젝트애쉬와 고로슬래그를 혼합하여 지오폴리머를 제조하였다. 리젝트애쉬와 고로슬래그의 치환율과 물유리와 NaOH의 농도에 따른 압축강도를 측정하였다. 압축강도 측정결과로는 알칼리 활성화제로 NaOH 1 wt%, 물유리 3 wt%와 전량 고로슬래그를 사용한 경우 재령 28일차 강도가 38.91 MPa의 성능을 나타내었다. 압축강도 증진의 중요한 요인은 알칼리 활성화제의 비율과 리젝트애쉬와 고로슬래그의 치환율에 의한 것이었다. In this study, geopolymer was prepared with reject ash and blast furnace slag using NaOH as an alkali activator and water glass. The aim of this study was to investigate the compressive strength variation according to the contents of NaOH and water glass and replacement ratio of reject ash (RA) and blast furnace slag (BS). The compressive strength measured after 28 days was 38.91 MPa for the geopolymer which consist of 100 % of BS with 1 wt% NaOH and 3 wt% water glass. The major factor for improving compressive strength was the alkali activator proportion and the replacement ratio of RA and BS.