• Resources Recycling
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• v.22 no.2
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• pp.29-36
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• 2013

Although Korean domestic production of flat panel displays totalled more than 48 trillion KRW in 2007, most of the flat panel display wastes have been land-filled or incinerated, which greatly overshadows Korean national prestige as a world leading producer and developer of flat panel display devices. Countries such as Japan or EU possess quite limited land-fill capability and have sought ways to dispose of WEEEs from environment-friendly perspective rather than recovery of valuable materials from the wastes. Considering relatively short cycle of about 5 years for flat panel display devices, it is estimated that more than 5 million units will be accumulated as wastes by 2015. Urban mining is a most suitable countermeasures against China's monopoly of rare and rare earth metals, which are contained in flat panel display wastes. Therefore, materials recycling of waste LCD units has to be developed and commercialized soon enough for economic and environment-friendly recovery of valuable resources hidden in LCD wastes.

• Resources Recycling
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• v.25 no.2
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• pp.17-24
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• 2016

This study aims at evaluating environmental impacts on recycling process of used small household appliances. The recycling process mainly consists of manual dismantling, crushing and various sorting processes to effectively recover valuable resources and to minimize environmental impact. In this study, life-cycle assessment (LCA) methodology is applied to analyze major environmental parameters such as GWP, ADP, POCP, EP, etc. One of the major impact categories on the weight basis in the recycling process is global warming (GWP) 57.1%, next to ADP 35.4% and POCP 4.8%, respectively. As a result of environmental impact on recovery of valuable resources/ton, the GWP of plastics for ABS is highest (33.7%) compared to ferrous metals (9.4%). The effects of environmental and economical benefit are also analyzed to compare with the amount of virgin materials to be recycled by recycled materials. In addition, recycled materials are also more economical in comparison to virgin materials due to the environmental avoiding effect by recycling. In conclusion, the key environmental issues related to the recycling of e-wastes are analyzed and therefore, the effective recycling process will contribute to mitigate global warming potential in the near future.

• Resources Recycling
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• v.24 no.3
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• pp.44-50
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• 2015

Recycling technologies would be required in consideration of increasing demand in lithium ion batteries (LIBs). In this study, the leaching behavior of Ni, Co and Mn is investigated with ammoniacal medium for spent cathode active materials, which are separated from a commercial LIB pack in hybrid electric vehicles. The leaching behavior of each metal is analyzed in the presence of reducing agent and pH buffering agent. The existence of reducing agent is necessary to increase the leaching efficiency of Ni and Co. The leaching of Mn is insignificant even with the existence of reducing agent in contrast to Ni and Co. The most conspicuous difference between acid and ammoniacal leaching would be the selective leaching behavior between Ni/Co and Mn. The ammoniacal leaching can reduce the cost of basic reagent that makes the pH of leachate higher for the precipitation of leached metals in the acid leaching.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.231-241
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• 2005

Laboratory experiments were performed to examine the effects of water content and to see if permittivity had sufficient sensitivity to identify subsurface contamination. Both real and imaginary permittivities of unsaturated sand were strongly governed by the volumetric water content. Especially, a linear relationship between real permittivity and volumetric water content was derived at high frequencies (MHz ranges). Heavy metals in pore fluid result in significant increases in the effective imaginary permittivity, due to ionic conduction, but decreases in the real permittivity arises due to the decreased orientational polarization of water molecules caused by hydration of ions. Clear increase in the effective imaginary permittivity with heavy metal concentration was found to be valuable in the application of electrical methods for detecting heavy metals in the subsurface. However, because the permittivity is primarily dependent on the volumetric water content of soil, pre-evaluation on the volumetric water content is required.

• Resources Recycling
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• v.21 no.6
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• pp.65-73
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• 2012

Selective catalytic reduction(SCR) catalysts are obtained from de-NOx system of thermoelectric power plant. A process was developed for valuable metals such as vanadium and tungsten recovery from spent SCR catalyst by using soda roasting followed by water leaching. Spent SCR catalyst having $V_2O_5$(1.23 mass %) and $WO_3$(7.73 mass %). For getting soluble metal forms of the targeted metals like vanadium and tungsten soda roasting process was implemented. In soda roasting process, sodium carbonate added 5 equivalent ratio at roasted temperature $850^{\circ}C$ with 120 min roasted time for $544{\mu}m$ particle size of spent SCR catalyst. After soda roasting process moved to water leaching for roasted spent catalyst. Before leaching process the roasted spent catalyst was grinded up to $-45{\mu}m$ size. The leaching time is 30 min at $40^{\circ}C$ temperature, 10 % pulp density. The final leaching efficiency obtained 46 % of vanadium and 92 % of tungsten from present process.

• Resources Recycling
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• v.31 no.4
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• pp.26-33
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• 2022

Owing to the demand for lithium-ion batteries, the recovery of valuable metals from waste lithium-ion batteries is required in future. A pyrometallurgical treatment is appropriate for recycling a large number of waste lithium-ion batteries, but Li loss to slag and dust present a significant challenge. This research investigated carbonation roasting and water leaching behaviors in Li-ion batteries by graphite addition to recover Li from the NCM-based cathode materials of waste Li-ion batteries. When 10 wt% of graphite was added, CO and CO₂ gases were emitted with a rapid weight reduction at apporoximately 850 K, when heated in Ar and CO₂ atmosphere. After the rapid weight reduction, NCM was decomposed and reduced to metal oxides and pure metals. In the carbonation roasting of black powder (NCM+graphite), O₂ is generated via the decomposition of NCM, and an oxides, such as Li₂O and NiO were were also generated. Subsequently, Li₂O reacts with CO₂ to generate Li₂CO₃, and a part of NiO was reduced by graphite to produce metal Ni. In addition, up to 94.5 % Li₂CO₃ with ~99.95 % purity was recovered via water leaching after carbonation roasting.

• Bulletin of the Korean Chemical Society
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• v.25 no.7
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• pp.969-976
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• 2004

Cassava peelings waste, which is both a waste and pollutant, was chemically modified using mercaptoacetic acid (MAA) and used to adsorb $Cu^{2+}\;and\;Cd^{2+}$ from aqueous solution over a wide range of reaction conditions at $30^{\circ}C$. Acid modification produced a larger surface area, which significantly enhanced the metal ion binding capacity of the biomass. An adsorption model based on the $Cu^{2+}/Cd^{2+}$ adsorption differences was developed to predict the competition of the two metal ions towards binding sites for a mixed metal ion system. The phytosorption process was examined in terms of Langmuir, Freundlich and Dubinin-Radushkevich models. The models indicate that the cassava waste biomass had a greater phytosorption capacity, higher affinity and greater sorption intensity for $Cu^{2+}\;than\;Cd^{2+}$. According to the evaluation using Langmuir equation, the monolayer binding capacity obtained was 127.3 mg/g $Cu^{2+}$ and 119.6 mg/g $Cd^{2+}$. The kinetic studies showed that the phytosorption rates could be described better by a pseudo-second order process and the rate coefficients was determined to be $2.04{\times}10^{-3}\;min^{-1}\;and\;1.98{\times}10^{-3}\;min^{-1}\;for\;Cu^{2+}\;and\;Cd^{2+}$ respectively. The results from these studies indicated that acid treated cassava waste biomass could be an efficient sorbent for the removal of toxic and valuable metals from industrial effluents.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.5
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• pp.224-228
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• 2014

Recently, the demands for separation/recovery of valuable metals such as nickel or tin from copper based alloys has been attracting much attention from the viewpoints of environmental protection and resource utilization. In this report, experimental results on concentration increasement of nickel and tin compared to the previous report are investigated. Ni is successfully separated by a organic solvent and reduced to the metal powder whose concentration is over 98 %. Sn is separated by a selective solution method and its concentration is increased to 97.5 % by three consecutive solution and reduction process. Crystal structure, surface morphology and microstructure of the separated samples are studied.

• Journal of the Korean earth science society
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• v.35 no.4
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• pp.259-266
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• 2014

This study was carried out to find an environmental friendly and effective way to leach Au and Ag from scrap of Printed Circuit Boards (PCBs) using sodium-hypochlorite solution. In an EDS analysis, valuable metals such as Cu, Sn, Sb, Al, Ni, Pb and Au were all found in PCBs. The highest leaching rates obtained were 1% of pulp density with a chlorine:hypochlorite of 2:1 and a concentration of NaCl at 2M. The highest Au recovery was observed with the addition of sodium metabisulfite to make a 3M solution. It is confirmed that the leaching agent (chlorine-hypochlorite) could effectively leach Au and Ag from Printed Circuit Boards (scrap parts) and the additive reagent sodium metabisulfite could easily precipitate Au from the chlorine-hypochlorite solution.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.459-473
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• 2014

The recent mass appearances of jellyfish in Korea have caused economic and social damage, as they plague swimmers and fishermen. However, jellyfish have high economic and nutritional value, and contain low levels of calories and hydrolysates. Thus, jellyfish are a natural, healthy food that can improve high blood pressure, bronchitis, and a multitude of other diseases. Here, we present research on the ecology, classification, bloom, damage caused, food component characterization, and tissues of jellyfish, with the aim of facilitating further study. Research on use of jellyfish as salted products, and for collagen and qniumucin would also be valuable. A jellyfish body is classified into three parts: the body, termed the umbrella; the oral arm; and the tentacle. Jellyfish are planktonic marine members of a group of invertebrate animals comprising the classes Schypozoa (phylum Cnidaria) and Cuboza. In Korea in 2012, jellyfish damage resulted in decreases of annual catch and commercial value estimated at 177 and 141 billion won, respectively. Because concentrations of heavy metals are below the safety limits for seafood, dried jellyfish appear to be safe raw materials for food. The proximate compositions of Nemopilema nomurai and Aurelia aurita were 97.1% and 96.5% moisture, 0.9% and 1.2% crude proteins, undetected and 0.1% crude lipids, and 1.7% and 1.8% ash, respectively. According to their total contents of essential, total, and non-essential amino acids, jellyfish gonads were deemed good-quality protein. Because the major functional components of jellyfish are collagen and qniumucin, jellyfish can be used salted, or these components of healthy diets can be extracted from them. For more effective use of jellyfish, unit costs should be decreased and safety guaranteed. Additionally, dehydrators attached to conveyor belts should be developed. Since jellyfish can be used throughout the year, they should be listed in the Korean Food Standards Codex as a food source.