The damaged spent fuel rods must be stabilized by encapsulation or dry re-fabrication technologies before geological disposal. For applying the dry re-fabrication technology, we manufactured a vertical type furnace to perform the fuel material recovery from damaged fuel rods by oxidative decladding technology. As driving forces to accelerate oxidative decladding rate, magnetic vibration and pulse hammering generated by a pneumatic cylinder were used in this study. The oxidative decladding efficiency and recovery rate of fuel oxide powder with rod-cut length, oxidation temperature and time, oxygen concentration, and gas mixtures were investigated using simfuel rod-cuts in a vertical furnace for fuel material recovery and powder quality improvement. The oxidative decladding was performed for 2.5-10 h as following operation parameters: simfuel rod-cut length of 50-200 mm, oxidative temperature from 450 to 580°C, oxygen concentration of 49.5 or 75.6%, and gas mixtures in O2/Ar or O2/N2. In magnetic vibration, oxidative decladding was progressed only at bottom portion of fuel rodcut. Whereas, oxidative decladding in pulse hammering was occurred at both top and bottom portions of fuel-rod. In pulse hammering method, the oxidative decladding conditions to declad rod-cuts of 50- 200 mm in length were established to achieve both decladding efficiency of ~100% and fuel material recovery rate of > 99%. These conditions were as follows: oxidation temperature and time at 500°C and 2.5-10 h, oxygen concentration at 75.6% under O2/N2 gas mixtures. As operation conditions for a pneumatic cylinder, stroking, actuating, and waiting times were 0.5, 3, and 12 s.

This study examined the influence of operating parameters on the electrosorptive recovery system of lithium ions from aqueous solutions using a spinel-type lithium manganese oxide adsorbent electrode and investigated the electrosorption kinetics and isotherms. The results revealed that the electrosorption data of lithium ions from the lithium containing aqueous solution were well-fitted to the Langmuir isotherm at electrical potentials lower than –0.4 V and to the Freundlich isotherm at electrical potentials higher than –0.4 V. This result may due to the formation of a thicker electrical double layer on the surface of the electrode at higher electrical potentials. The results showed that the electrosorption reached equilibrium within 200 min under an electrical potential of –1.0 V, and the pseudo-second-order kinetic model was correlated with the experimental data. Moreover, the adsorption of lithium ions was dependent on pH and temperature, and the results indicate that higher pH values and lower temperatures are more suitable for the electrosorptive adsorption of lithium ions from aqueous solutions. Thermodynamic results showed that the calculated activation energy of 22.61 kJ mol–1 during the electrosorption of lithium ions onto the adsorbent electrode was primarily controlled by a physical adsorption process. The recovery of adsorbed lithium ions from the adsorbent electrode reached the desorption equilibrium within 200 min under reverse electrical potential of 3.5 V.

In this study, an experiment is performed to recover the Li in Li2CO3 phase from the cathode active material NMC (LiNiCoMnO2) in waste lithium ion batteries. Firstly, carbonation is performed to convert the LiNiO, LiCoO, and Li2MnO3 phases within the powder to Li2CO3 and NiO, CoO, and MnO. The carbonation for phase separation proceeds at a temperature range of 600oC~800oC in a CO2 gas (300 cc/min) atmosphere. At 600~700oC, Li2CO3 and NiO, CoO, and MnO are not completely separated, while Li and other metallic compounds remain. At 800 oC, we can confirm that LiNiO, LiCoO, and Li2MnO3 phases are separated into Li2CO3 and NiO, CoO, and MnO phases. After completing the phase separation, by using the solubility difference of Li2CO3 and NiO, CoO, and MnO, we set the ratio of solution (distilled water) to powder after carbonation as 30:1. Subsequently, water leaching is carried out. Then, the Li2CO3 within the solution melts and concentrates, while NiO, MnO, and CoO phases remain after filtering. Thus, Li2CO3 can be recovered.

전기⋅전자산업이 급격하게 발전함에 따라 유가금속 및 희소금속의 수요가 급증하고 있다. 유가금속들은 주로 제련산업 공정에서 다량 방출되며, 회수기술 부족으로 중화, 치환, 흡착을 통해 폐기되어 큰 비용으로 경제적이지 못하다. 이에 분리막을 통한 유가금속회수 소재개발의 필요성이 강조되고 있다. 유가금속이 포함된 습식제련 공정 침출액(15% 황산 용액, 온도 60°C)은 다량의 다가이온과 1가이온을 포함하고 있기 때문에 이온별 분리가 가능해야 하며, 특히 구리와 같은 2가 유가금속 분리성능이 우수해야 한다. 또한, 지속적인 분리/농축을 위해 산에 대한 안정성이 중요하다. 따라서 본 연구를 통해 2가 금속 배제율 98%, 유량 33GFD 성능을 1개월 이상 유지하는 나노분리막 제조 연구 개발을 수행하고 있다.

National statistics of solid waste indicate that, although the amount of combustible wastes from household sectors is decreasing, the amount of waste that is buried in landfills increases each year. And the increasing rate of combustible wastes from industrial sectors is higher than the decreasing rate of combustible wastes from household sectors. Combustible waste, once screened, can be used as a potential energy resource contributing to resource circulation. Therefore, the objective of this study was to predict the amount of waste materials to be recovered and recycled by landfill mining and reclamation (LFMR), based on material flow analysis for four existing landfills. In this study, the landfills analyzed by material flow analysis were classified into types 1 to 4 by considering the status of the landfill and incineration situation. In order to perform material flow analysis, volume increase rate and bulk density were applied to the methodology employed in previous studies. In addition, material flow analysis software ‘STAN 2.0’ was used for the analysis. As a result of analyzing the average value of four landfills, the landfilled waste was classified as 93.9 m3 (73.7%) of combustible waste, 9.2 m3 (7.3%) of incombustible waste, and 24.3 m3 (19.1%) of soil matter. So, 73.7% can be incinerated or recovered by energy, 7.3% can be recycled as materials and reclaimed, and 19.1% can be recycled as landfill cover materials based on weight. The results of the material flow analysis carried out in this study are expected to be used to predict the amount of waste materials landfilled to be recovered by the material flow analysis during landfill mining processes.

폐기물은 발생원을 기준으로 생활폐기물, 사업장폐기물 및 건설폐기물로 구분된다. 폐기물 처리는 재활용을 우선적으로 정책이 이루어지고 있다. 그러나 폐기물을 재활용하기 위해서는 기술적인 한계성과 경제성 등이 해결되어야 하며 이러한 이슈가 극복되지 않으면 재활용에는 한계가 따른다. 국내에서 도입된 네가티브 재활용 제도가 다양한 기술을 재활용로서 적용될 수 있도록 하였으며, 그 중 폐기물 에너지화 기술로써만 인식되어온 폐기물 가스화 기술은 에너지회수 기술 뿐 만 아니라 원료를 대체할 수 있는 재활용 기술로도 적용될 수 있게 되었다. 폐기물의 재활용은 물질재활용 기술로서 3R기술 위주로 재활용되어 왔으나 화학전환 기술에 의한 재활용을 위해서는 가스화 기술이 많은 기여를 할 것으로 기대된다. 또한 폐기물의 에너지 회수기술은 소각에 의한 에너지회수 또는 고형연료를 생산하여 연소보일러에 의한 에너지회수 방법이 주로 이용되어 왔으며 이러한 기술은 열에너지를 회수하는 기술에 국한되어 있다. 그러나 폐기물 가스화 기술은 열에너지와 화학에너지의 생산이 가능하므로 다양한 에너지로의 회수 기술과 고효율 에너지 이용기술의 적용이 가능한 기술이다. 따라서 본 연구에서는 폐기물 가스화를 통한 에너지회수 기술과 화학전환 기술로서 원료대체를 통한 재활용 기술로서의 특성을 고찰하였다. 폐기물 가스화 기술은 가연성물질이 함유된 폐기물의 대부분을 대상으로 적용이 가능하지만 합성가스를 이용하는 기술에 따라서 합성가스의 생산품질을 만족하기 위해서는 폐기물의 적정 발열량이 확보되어야 된다. 폐기물의 종류에 따라 기준은 달리 적용되겠지만 저위발열량 기준으로 3,200 kcal/kg이상인 경우 안정적인 합성가스를 생산할 수 있다고 판단되며, 폐기물종류 및 이용기술에 따라서는 3,000 kcal/kg이상인 경우 합성가스 생산품질을 유지할 수 있다. 폐기물 가스화를 통해 생산된 합성가스를 에너지회수 기술로서는 스팀터빈, 가스터빈, 가스엔진, 연료전지 등의 기술을 적용할 수 있고, LNG, 경우, 석탄, LPG 등 화석연료를 대체하는 가스연료로 적용할 수도 있다. 또한 합성가스의 주요성분인 일산화탄소와 수소는 고순도 수소 및 고순도 일산화탄소 자체로도 원료대체가 가능하며, 화학촉매 또는 미생물촉매 전환 공정을 통해 다양한 화학원료로 대체하는 재활용기술로서의 적용이 가능한 특성을 가지고 있다.