• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.92-97
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• 2004

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.05a
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• pp.56-60
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• 2006

In 2005, the imports of titanium metals was about 22.8 million US$(7,700 tons) in Korea. New scrap produced was estimated to be 359 tons and the exports were about 352 tons. Generally scrap is recylced into titanium ingot either with or without virgin metal using traditional vacuum-arc-melting and cold hearth melting. In Korea, there is no titanium ingot producers(recyclers). In this paper, the brief summary of major titanium melting technology, such as vacuum arc remelting(VAR), electron beam melting(EBM), plasma arc melting(PAM) is given and discussed. In view of titanium market situation of Korea, the technological development of ingot production from scrap is big problem to be solved in order to realize extensive cost reduction for titanium products.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.214-223
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• 2005

In order to recover valuable metals from fine-grained electronic waste, bioleaching of Cu, Zn, Al, Co, Ni, Sn and Pb were carried out using Aspergillus niger as a leaching microorganism in a shaking flask. Aspergillus niger was able to grow in tile presence of electronic scrap. The formation of organic acids(citric and oxalic acid) from Aspergillus niger caused the mobilization of metals from waste electronic scrap. In a preliminary study, in order to obtain the data on the leaching of Cu, Zn, Al, Co and Ni, the metal leaching behaviours were accomplished using Organic acid(Citric acid and Oxalic acid) instead of Aspergillus niger. At the electronic scrap concentration of 50g/L, Aspergillus niger were able to leach more than 95% of the available Cu, Co. But Al, Zn, Pband Sn were able to leach about 15-35%. Ni and Fe were detected in the leachate less than 10%.

• Resources Recycling
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• v.12 no.6
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• pp.57-63
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• 2003

In this study, the separation of neodymium was investigated from NdFeB permanent magnet scrap. Decomposition and leach-ing process of NdFeB permanent magnet scrap by oxidation roasting and sulfuric arid leaching were examined. Neodymium could be separated from iron by double salt precipitation using sodium sulfate. The optimum conditions established for decom-position and leaching are as follows: oxidation roasting temperature is $500^{\circ}C$ for sintered scrap and $700^{\circ}C$ for bonded scrap, concentration of sulfuric acid in leaching solution is 2.0 M, leaching temperature and time is $50^{\circ}C$ and 2 hrs, and pulp density is 15%. The leaching yield of neodymium and iron was 99.4% and 95.7% respectively. The optimum condition for separation of neodymium by double-salt precipitation was 2 equivalents of sodium sulfate and $50^{\circ}C$ The yield of neodymium was above 99.9%.

• Resources Recycling
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• v.27 no.3
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• pp.93-99
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• 2018

Effective extraction of platinum group elements by dissolving waste platinum scrap from the display industry and solvent extraction, was studied. The extracted platinum solution was prepared as a precursor solution for diesel automotive exhaust gas purification catalyst and its catalytic activity was tested. The behavior of aqueous species of platinum was investigated through solution chemistry and based on the existence and behavior of these chemical species, the possibility of extraction and separation was established. By dissolving waste scrap by electrochemical method, the dissolution time of scrap was shortened and the extraction efficiency was increased. Through separation and removal of rhodium component, solvent extraction by TBP, and stripping by hydrochloric acid, Pt-Chloride-$H_2O$ solution was prepared. And then, an platinum amine complex solution through amination reaction with this solution as a raw material was prepared. The possibility of producing high-value platinum compounds from platinum group waste scrap was investigated by preparing platinum amine complex solution and then examining the catalytic activity with this amine precursor on the combustion reaction of carbon black.

• Resources Recycling
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• v.14 no.5 s.67
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• pp.24-31
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• 2005

In order to recover valuable metals from fine-grained electronic waste, bioleaching of Cu, Zn, Al, Co, Ni, Fe, Sn and Pb were carried out using Aspergillus niger as a leaching microorganism in a shaking flask. Aspergillus niger was able to grow in the presence of electronic scrap. The formation of organic acids(citric and oxalic acid) from Aspergillus niger caused the mobilization of metals from waste electronic scrap. In a preliminary study, in order to obtain the data on the leaching of Cu, Zn, Al, Fe, Co and Ni from electronic scrap, chemical leaching using organic acid(Citric acid and Oxalic acid) was accomplished. At the electronic scrap concentration of 50 g/L, Aspergillus niger were able to leach more than 95% of the available Cu, Co. But Al, Zn, Pb and Sn were leached about 15-35%. Ni and Fe were detected in the leachate less than 10%.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.220-224
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• 2001

Waste tires are a significant problem with the increasing in number of automobiles. Therefore, many researches have been studied on this field. Recycling is the one of the popular method aspect to environmental and economical in the treatment methods of the waste tire, which loads that the reuse of scrap tire rubber has been a challenge in the past. However, it is not easy method to melt down and mold into new products because the in rubber is a cross-linked polymer. Most difficulty in recycling is the recycled product is not economic. Therefore, the goal of this study is to develop the high valuable products for reused waste tires. In this paper, we try to make an economic recycled technology using scrapped waste tires. This technology may applied for manufacturing the end products such as a rubber block and a ballast mat for high-speed train.

• Resources Recycling
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• v.20 no.1
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• pp.69-79
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• 2011

Recently, magnesium alloys are in the spotlight as a promising materials in the fields of automobile parts and electronic appliances due to their merits representing light weight, high specific strength, damping property, shielding of electromagnetic wave and so on. However, magnesium alloys show a poor formability at room temperature because magnesium has HCP crystal structure with limited slip planes and strong basal texture is formed during plastic deformation process such as rolling and extrusion. Therefore, many R&D efforts have been paid for improvement of formability through grain refinement, texture control and various forming technologies. This paper is giving an overview about recent achievements on control of microstructures, forming technologies and magnesium scrap recycling.

• Resources Recycling
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• v.17 no.3
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• pp.21-28
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• 2008

Using the post-consumer waste and edge scrap mixed PET with small amount PP air filter elements of automobiles. It was studied that these mixed waste plastics of the various types of the PET were practicable for the material recycling. Various waste PET/PP plastics were collected, crushed, dried in vacuum, and extruded to recycled PET/PP chips. These chips were mixed with three kinds compatibilizers, EVA, MBS, and recycled PVB of the ratio of $3{\sim}10wt.%$ for the purpose of the compatibility for the post-consumer waste and edge scrap. We investigated mechanical and thermal properties of PET/PP mixtures which were compound with the weight ratio of compatibilizers. Compatibilizer, MBS application was showed the most excellent mechanical properties in the range of the $3{\sim}5wt.%$ EVA application was displayed good impact strength and thermal property in the range of $3{\sim}5wt.%$ Last, recycled PVB application was showed poor mechanical properties in the whole range ratio of the PVB.

• Resources Recycling
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• v.9 no.4
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• pp.50-55
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• 2000

Recycling technology of aluminum foil scraps into aluminum flake powder by ball milling in dry or wet conditions was studied. Aluminum foil were laminated each other, elongated through microforging by the falling balls, fragmented into small foils and then changed into flake powder during ball milling. It is also possible to recycle foil scraps with thickness less than $60\mu\textrm{m}$ into aluminum paste by wet ball milling. As initial foil thickness decreases, foil is easily milled to flake powder by wet milling in mineral spirits. the appearance and the opaque character of glass painted with aluminum paste obtained by wet milling of foils are similar to those of aluminum paste made by ball milling of gas atomized powder.