Enhancement of gold recovery during lead fire assay by salt-roasting

최낙철,김봉주,조강희,유돈상,박천영 한국자원공학회 2014 Geosystem engineering Vol.17 No.4

The aim of this study was to investigate the effect of a simple and economical salt-roasting method on the gold recovery of a conventional lead fire assay. An enhanced gold recovery of 30.99 g/ton (16.82%) was obtained by roasting a gold concentrate at 750°C, but this was further enhanced to 40.44 g/ton (21.95%) at the same temperature with the addition of 20% salt. The fact that the maximum recovery was obtained at a roasting temperature of 750°C was attributed to the fact that pyrites within the concentrate contained invisible gold, with the addition of salt enhancing the decomposition of these pyrites. Thus, by treating the gold concentrate with a combination of conventional and salt roasting, its gold content was increased and the loss of gold to the glass slag was reduced. Finally, it was also observed that the amount of gold loss with an amorphous specimen was less than that of samples containing galena.

매몰 시간의 경과에 따른 구제역 가축 매몰지 침출수 특성에 관한 연구

최낙철,최은주,김봉주,박정안,김성배,박천영,Choi, Nag-Choul,Choi, Eun-Ju,Kim, Bong-Ju,Park, Jeong-Ann,Kim, Song-Bae,Park, Cheon-Young 대한자원환경지질학회 2013 자원환경지질 Vol.46 No.4

In this study, the physicochemical properties of leachate and the bacteria existence in leachate using molecular biology methods for 4 animal carcass disposals on the disposal lapse time was analyzed. The result of leachate physicochemical analysis in the middle stage (been buried 20 months) showed higher EC, DO, $HCO_3{^-}$, TOC, T-N and $SO_4{^{2-}}$ concentration compared to the first stage data (been buried 5 months). For identification of leachate using 16S rRNA method, Lysinibacillus sphaericus, Bacillus pumilus, Pseudoclavibacter helvolus, Pseudochrobactrum saccharolyticum and Corynebacterium callunae in the first stage, Bacillus cereus, Lysinibacillus sphaericus, Bacillus circulans and Corynebacterium glutamicum in the middle stage was observed, while there were detections of pathogenicity bacteria such as B. cereus and L. sphaericus. This study improves our knowledge of the fate and transport in geologic media, treatment, risk analysis on the leachate from animal carcass disposal sites.

소규모 하수 재이용을 위한 디스크필터의 처리 효율 증진에 관한 연구

최낙철,김봉주,박성용,박형우,이성재,박천영,Choi, Nag-Choul,Kim, Bong-Ju,Park, Seong-Yong,Park, Hyeong-U,Lee, Sung-Jae,Park, Cheon-Young 한국지하수토양환경학회 2015 지하수토양환경 Vol.20 No.4

The aim of this study was to enhance of the Discfilter process (maximum treatment capacity - 500 ton/day) removal efficiency for small-scale wastewater reclamation under various influent wastewater conditions (with / without coagulation process, coagulant content and temperature). The result of chemical resistance test for fiber filter in the Discfilter that weight loss was obtained with 0.535% under pH 3, 0.092% under pH 9 and 0.028% under 10% NaClO. The removal efficiency test of Discfilter process on the with / without coagulation process showed that with coagulation process condition was occurred COD_Mn of 42.26 ± 0.61, BOD₅ of 88.72 ± 0.44, T-P of 84.67 ± 0.72 and SS of 90.58 ± 0.61. The removal efficiency of Discfilter process on the coagulant content (4.5, 5.0 and 5.0 mL/min) and temperature (< 10℃, 10℃~ 20℃ and > 20℃) conditions were increased as coagulant content and temperature increased. This study demonstrated the potential application of Discfilter process for small-scale wastewater reclamation.

Microfluidic Chip을 이용한 PDA Bead 제조 및 특성 분석

최낙철(Nakchul Choi),송시몬(Simon Song) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5

미세유동칩에서 이온 분극 현상을 이용한 cysteine 검출 센서 개발

최낙철(Nakchul Choi),송시몬(Simon Song),이진오(Jin oh Lee),김영필(Young-Pil Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

미세 유동 칩에서 이온분극현상을 이용한 시스테인 검출

최낙철(N. Choi),송시몬(S. Song),이진오(J. H. Lee),김영필(Y. P. Kim) 한국가시화정보학회 2018 한국가시화정보학회 학술발표대회 논문집 Vol.2018 No.4

Microchip IEF와 fluorescent nanoprobe를 이용한 인산화 효소 활동 분석

최낙철(Nakchul Choi),송시몬(Simon Song) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5-2

Microfluidic Chip를 이용한 PDA Bead 열 감응 센서 개발

최낙철(Nakchul Choi),송시몬(Simon Song) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12

This study addresses a fabrication process of PDA bead temperature sensor using microfluidic technique and characteristic analysis of the sensor. We synthesized liquid diacetylene monomer, methyl pentacosa-10,12-diynoate(PCDA-Me), and prepared PDA supramolecules displayed a sharp blue-to-red colorimetric transition. Entire fabrication process of PDA bead sensor consists of microdroplet generation, crystallization, and activation. Microdroplet is easily fabricated by sheathing effect and its size can be controlled by variation of flow rate ratio between core and sheath flow. After PCDA-Me droplets are collected into a reservoir (filled with aqueous solution), they are crystallized at about 0℃, and then, activated by 254 nm UV exposure showing blue color. To evaluate a sensing performance of the PDA microdroplet, we apply temperature changes to the microdroplet and analyze red fluorescence emitted from PDA microdroplet.

지질매질체내에서 계면활성제가 박테리아 이동 증진에 미치는 영향

최낙철(Nag Choul Choi),박성직(Seong Jik Park),김성배(Song Bae Kim),김동주(Dong Ju Kim),이성재(Seong Jae Lee) 大韓環境工學會 2010 대한환경공학회지 Vol.32 No.11

본 연구에서는 지질매질체내에서 계면활성제(비이온성 계면활성제(Tween 20), 생계면활성제)가 박테리아(Bacillus subtilis ATCC 6633)의 이동 증진에 미치는 영향을 분석하였다. 계면활성제가 존재하는 다양한 실험조건에서 석영모래(입경분포: 0.5~2.0 mm, 평균입경: 1.0 mm)로 충진된 칼럼을 이용하여 박테리아의 이동에 관한 칼럼실험을 수행하였고, 박테리아 파과곡선으로부터 질량회수율과 부착효율 등을 정량화하였다. 실험결과, MSM(박테리아 성장에 필요한 무기물 배지)의 존재 하에서 매질체 표면에 박테리아의 부착이 상당히 증가하였는데(특히, 주입부분에), 이는 MSM으로 인한 이온강도의 증가 때문이다. 계면활성제가 존재할 경우에는, 계면활성제로 인하여 매질체내에서 박테리아 이동이 증진됨을 관찰할 수 있었다. 또한, MSM과 생계면활성제 주입방법에 따른 박테리아의 이동을 비교한 결과, 박테리아의 이동 증진을 위한 주입조건은 박테리아를 함유한 MSM용액보다 계면활성제를 선주입하거나, 또는 MSM용액과 계면활성제를 동시주입하는 것이 효과적임을 알 수 있었다. 본 연구를 통해 계면활성제의 존재와 주입방법이 박테리아의 이동에 영향을 미칠 수 있음을 알 수 있었다. This study investigated the effect of surfactants (nonionic surfactant (Tween 20), biosurfactant) on enhancing transport of bacteria (Bacillus subtilis ATCC 6633) in geological materials. Column experiments were performed under various surfactant conditions with columns packed with quartz sand (particle size distribution: 0.5~2.0 mm, mean diameter: 1.0 mm). Bacterial mass recovery, sticking efficiency, and other parameters were quantified from breakthrough curves. Results indicate that bacterial attachment to sand surfaces increased considerably in the presence of mineral salt medium (MSM), especially at the inlet, which was due to the increase of ionic strength by MSM. It was observed that bacterial transport in sand columns was enhanced in the presence of surfactant. Results also show that simultaneous injection of both surfactant and MSM or pre-injection of surfactant was more effective in bacterial transport enhancement than after-injection of surfactant. This study suggests that transport of bacteria in geological materials could be influenced by surfactants and their injection methods.

Spirulina sp. 대량생산 목적의 저비용 배지 적용에 관한 경제성 분석

최낙철 ( Nag-choul Choi ),김봉주 ( Bong-ju Kim ),조강희 ( Kang-hee Cho ),이성재 ( Sung-jae Lee ),박천영 ( Cheon-young Park ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.3

The aim of this study was to investigate the economic of a culture condition through comparative analysis to Spirulina platensis growth characteristic under various medium conditions for cost effective production of Spirulina sp.. Growth experiments were performed with S. platensis under various culture medium conditions (SOT, Zarrouk and SP) and various low cost medium conditions (N:P:K ratio). Growth tests for culture medium demonstrated that the SP medium was effective in S. platensis with the maximum biomass (2.3g/L) and minimum medium making cost per production mass (140.44 won/g). Growth tests for low cost medium results showed that the maximum biomass and minimum medium making cost per production mass was obtained under medium A and B were maximum biomass of 1.65, 1.67 g/L and 2.12, 2.10 won/g, respectively.