Effects of Electro-Generated NaOCl on the Destruction of Cyanide and Precipitation of Copper from WPCB Leach Solution

( Mooki Bae ),( Hyunju Lee ),( Youngmin Oh ),( Soo-kyung Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

The removal of cyanide and copper from the WPCBs leach solution using electro-generated NaOCl is investigated. WPCB leach solution was provided through cyanide-based leaching to enhance the selective leaching of gold under minimizing the coleaching of base metals. The efficiency of the destruction of cyanide and precipitation of copper was found to be higher with electro-generated NaOCl (after 5 generation cycles) than that of reagent-grade NaOCl (grade reagent; chlorine concentration, 4.7 g/L). A detailed study of the influential parameters revealed the optimal conditions to be electro-generation of NaOCl, 5 cycles; volume ratio of N/L (NaOCl/leach solution), 1/1; pH, above 9; temperature, 50 ℃; and time, 2 h. Through alkaline chlorination used electro-generated NaOCl, approximately 99% free cyanide and 98% copper were removed by the destruction and precipitation respectively. However, 82% copper could be removed by using reagent-grade NaOCl while most of the cyanide destructed. The precipitated copper powder using electro-generated NaOCl followed the autocatalytic model with the activation energy value of 13.4 kJ/mol. Copper precipitated with reagent-grade NaOCl could also follow the autocatalytic model with the higher value of activation energy (30.9 kJ/mol). The results revealed that the electro-generated NaOCl can eliminate the cyanide and copper with remaining only gold in the final solution.

Study on Extraction of Pt from Membrane Electrode Assembly

( Mooki Bae ),( Kyungsob Choi ),( Hongin Kim ),( Sookyung Kim ),( Hyunju Lee ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Pt/C catalyst is the main material for membrane electrode assembly (MEA), which is a key component of polymer electrolyte membrane fuel cell (PEMFC). Since MEA accounts for about 45% of the stack price, recycling is essential in securing raw materials. In this study, heat treatment was performed to separate the Pt/C catalyst from the membrane electrode assembly (MEA), and the separated catalyst was leached using hydrochloric acid with oxidants to recover platinum. DTA/TG experiments were performed to confirm the pyrolysis temperature, and most organic materials such as Nafion membrane and plastics were decomposed at about 500~600℃. The samples pretreated at about 600℃ were used for the leaching experiment, and the platinum leaching efficiency according to the hydrochloric acid concentration, leaching time, and type of oxidizing agent was compared. ~95% Pt was recovered through a dissolution experiment in 1 M HCl and an oxidizing agent (H₂O₂, 5.0% v/v) within 2 h. In the case of the sample treated at a low temperature, it was difficult to separate organic matter and Pt/C, and the resorption of platinum decreased the leaching efficiency. This is because the re-adsorption of ionized platinum during platinum leaching from Pt/C adversely affects the leaching of undecomposed carbon. Therefore, the effect of the change in Pt/C of the heated sample on the leaching efficiency was confirmed through FT-IR, XPS, and TEM analysis.

Electrowinning of gold from a dilute solution using hydrocyclone-type cell

Bae Mooki,Kim Hongin,Kim Sookyung,Lee Hyunju 한국자원공학회 2022 Geosystem engineering Vol.25 No.4

The redox reaction mechanism of gold−cyanide [Au(CN)2 −] during hydrocyclone electrowinning was investigated in this work by conducting Hull cell test, potentiodynamic polarization, and computational fluid dynamics (CFD) simulations. A leaching solution of waste printed circuit boards (WPCBs) was prepared as an electrolyte, and the effects of flow rate and applied voltage on the recovery of gold and destruction of cyanide through hydrocyclone electrowinning were investigated. A numerical simulation of the flow field in the cell was performed, and the results were visualized by conducting a finite element analysis in FLUENT. The CFD simulations and Hull cell test showed that the cylindrical cathode region had a flow velocity of ~11.05 m·s−1, which was higher than that at the center of the cylindrical part (<6.45 m·s−1). The optimum conditions for electrowinning were found to be as: an electrode distance of 4.9 mm and a current density of 73.78 mA·cm−2. The anodic polarization results showed that an Ir-based mixed metal oxide (MMO) anode could more efficiently oxidize the free cyanide because of its high current density than other types of anodes (Ir-based MMO: 299.3 mA·cm−2 > SS304: 3.5 mA·cm−2 > Pt-coated Ti: 1.3 mA·cm−2). Through the demonstrated hydrocyclone electrowinning test, the gold concentration could be decreased from 100 to 0.24 mg·L−1 within 12 h while destroying almost total amount of free cyanide in a day.

사용 후 막전극접합체의 열처리에 따른 백금 침출 거동

배무기 ( Mooki Bae ),최경섭 ( Kyungsob Choi ),이현주 ( Hyunju Lee ),김수경 ( Sookyung Kim ) 한국폐기물자원순환학회 2022 한국폐기물자원순환학회 심포지움 Vol.2022 No.1

사용 후 막전극접합체의 열처리에 따른 백금 침출 거동

배무기 ( Mooki Bae ),최경섭 ( Kyungsob Choi ),이현주 ( Hyunju Lee ),김수경 ( Sookyung Kim ) 한국폐기물자원순환학회 2022 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2022 No.-

사이클론 전해조의 업그레이드와 이를 이용한 금 회수 최적화 실증 연구

배무기 ( Mooki Bae ),김수경 ( Sookyung Kim ),손정수 ( Jeongsoo Sohn ),김홍인 ( Hongin Kim ),문윤실 ( Yoonsil Moon ),장영주 ( Yungju Jang ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 추계학술발표논문집 Vol.2018 No.-

폐액 내 존재하는 금의 회수법은 크게 수지법, 금속치환법 그리고 전해채취법으로 나눌 수 있다. 수지법은 금 이온을 수지에 흡착하고 나중에 탈착하여 금을 분리정제하는 방법이며, 금속치환법은 아연이나 알루미늄 등 전위가 낮은 금속분말을 금 이온이 존재하는 용액에 넣음으로써 자신들은 용해되고 금은 환원시키는 방법이다. 전해채취법은 양극과 음극으로 된 전극에 일정한 전압과 전류를 제공함으로써 음극에 금을 환원석출시키는 방법이다. 수지법은 값비싼 수지로 인해 공정비용이 많이 들고 흡착과 탈착 반응이 오래 걸리는 문제가 있으며, 금속치환법은 상대적으로 비용이 저렴하나 석출되는 금의 순도가 90% 정도로 그리 높지 않고 환경부하가 큰 단점이 있다. 전해채취법은 기본적으로 금 이온의 농도가 수 천 ~ 수 만 ppm 이상이어야만 음극으로의 금 이온 물질이동에 따른 전해반응이 가능하여 금을 회수할 수 있어 금 이온 농도가 수 백 ppm 이하에서는 적용할 수 없다. 본 연구에서는 일반적 전해반응이 불가능한 수 백 ppm 이하의 금 이온 농도가 존재하는 폐액으로부터 금을 8시간에 99% 전해 회수할 수 있는 사이클론 전해조에 대하여 연구하였다. 특히, 실제 재활용 공정에 적용하여 보다 효율적으로 금을 회수하기 위한 사이클론 전해조의 업그레이드 방안과 폐액 발생 현장에 직접 적용하기 위한 금 회수 규모 확대 실험을 수행하여 최적의 금 회수 실증공정을 도출하고자 하였다. 그 결과 사이클론 전해조에서의 hull cell 시험으로 전류와 극간거리에 따른 금의 환원석출 거동에 대해 플랫폼 데이터를 확보하였으며, 전도보조제와 같은 첨가제의 농도에 따른 금 회수 최적 실증공정을 도출하였다. 사사: 이 논문은 과학기술정보통신부 산학연 협력ㆍ실용화ㆍ기술사업화사업의 2017년 연구성과사업화지원 기술업그레이드 R&D(1차) 사업에 의하여 연구되었으며, 이에 감사드립니다.

라틴방격분석법을 이용한 단속류도로에서의 유고감지기법 개발

모무기(Mo,Mooki),김형진(Kim,Hyung Jin),손봉수(Son,Bongsoo),김대훈(Kim Dae Hun) 대한토목학회 2011 대한토목학회논문집 D Vol.31 No.5D

본 연구에서는 단속류 도로에서의 유고상황을 감지할 수 있는 새로운 유고감지기법을 제시하였다. 유고감지를 위하여 적용된 방법은 교통특성들을 이용한 라틴방격(Latin Square)분석법이다. 라틴방격분석법을 이용하여 기존 연구사례에서 시도했던 방법과는 다르게 차로별, 시간대별 교통특성의 변화를 분석하여 유고상횡을 감지하였다. 사용된 교통특성자료는 맑은 기상상태에서 정상운영시 또는 유고발생시 관측된 교통량, 속도, 점유율 자료이며, 유고시 자료는 2차로에서 10분간 유고가 발생했었던 자료이다. 정상운영시 및 유고발생시에 대한 교통상황을 감지하기 위하여 교통량, 속도 및 점유율 등을 기준으로 각각 라틴방격분석을 시행했다. 분석결과, 라틴방격분석을 이용하여 교통상황을 감지하는 경우, 교통량을 기준으로 교통상황을 감지하는 것이 다른 교통특성을 기준으로 교통상황을 감지하는 것보다 감지능력이 우수한 것으로 나타났다. In this study, a new method which can detect incidents in interrupted traffic flow was suggested. The applied method of detecting the incident is the Latin Square Analysis Method by using traffic traits. In the Latin Square Analysis, unlike other previously tried methods, the traffic situation was analyzed, this time considering the changes in traffic traits for each lane and for each time period. The data used in this study were the data observed in the actual field with fine weather. The traffic volumes, the vehicle speed and the occupancy rate were collected on the interrupted flow road. The data were collected in normal and incident situations. The incidents occurred on the second lane, the time of persistent incidents was set to 10 minutes. The Latin Square Analyses were performed using the collected data with the traffic volume, with the vehicle speed or with the occupancy rate. As a result in this study, in case of detecting the traffic situations with Latin Square Analysis, it will be more successful to apply traffic volume to detect the traffic situations than to apply other factors.

Effects of Robot-Mediated Gait Training Combined with Virtual Reality System on Muscle Activity: A Case Series Research

Seoyoon Heo,Mooki Kim,Wansuk Choi 국제물리치료연구학회 2020 Journal of International Academy of Physical Ther Vol.11 No.2

Background: Previous robot-mediated gait training has been proven several limitations such as pointless repeated motion training, decreased presence, etc. In this research, adult stroke patients were participated in robot-mediated gait training accompanied with or without virtual reality program. Objectives: Exploring whether the results indicated virtual reality system has contribution to muscle strength and balance ability. Design: A case series research, cross-over trial. Methods: Eleven participants (male 4, female 7) with adults diagnosed as stroke from medical doctor ware engaged. The participants received 2 treatment sessions of identical duration, robot-assisted gait training with virtual reality and robot-assisted gait training with screen-off randomly crossed over include 1-day for each person of wash-out period. The parameter was muscle activity, the researchers assessed sEMG (surface electromyography). Results: The result showed less muscle activities during training in robotassisted gait training with virtual reality circumstances, and these indicated muscles were gluteus medius muscle, vastus medialis muscle, vastus intermedius and vastus lateralis muscle, semimembranosus muscle, gastrocnemius- lateral head, and soleus muscle (P<.05). Conclusion: In this study, we analyzed the outcome of muscle activity for clinical inference of robot-assisted gait training with virtual reality (VR). Less muscle activity was measured in the treatment accompanied by VR, therefore, a more systematic, in-depth and well-founded level of follow-up research is needed.

Recovery of platinum, gold, and palladium using cyclone electrolyzer

( Hyunju Lee ),( Mooki Bae ),( Soo-kyung Kim ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Traditionally, precious metal recovery methods include electrolytic extraction, metal cementation, and ion exchange. However, these technologies can be applied to resources containing high concentrations of precious metals, but recovery is very difficult in low-concentration resources for economic reasons such as slow metal reduction rate and continuous consumption of ion resin. The electrolytic recovery technology using a cyclone can recover valuable metals from low-concentration resources that are impossible in the commercial technology process due to the special structure (improving the mass transfer rate) of the cyclone. In addition, since it can be automated and consumes low power, it has advantages as an eco-friendly technology as well as a reduction in recovery cost. In this study, a cyclone electrolyzer was used to effectively recover gold, platinum, and palladium, and in particular, the reduction behavior of each metal was analyzed using cyclic voltammetry. We were prepared for cyclic voltammetry and cyclone electrolytic recovery experiments with the leaching solutions contained in 2% HCl. As a result, after 8 hours of cyclone electrolysis, the recovery rate of precious metals was about 99% effectively.

식품 중 설폰아마이드계 동물용의약품의 잔류실태

정지윤(Jiyoon Jeong),홍무기(Mooki Hong),최동미(Dongmi Choi) 한국분석과학회 2007 분석과학 Vol.20 No.1