• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.280-280
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• 2005

• Journal of Korea Foundry Society
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• v.28 no.2
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• pp.52-56
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.9.1-9.1
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• 2008

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.10a
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• pp.89-90
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• 2016

• 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.

• Resources Recycling
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• v.24 no.1
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• pp.21-27
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• 2015

The present study describes the process of producing low oxygen content alloy powder from Ti-6Al-4V and Ti-8Al-1Mo-1V (AMS 4972) alloy scraps using hydrogenation-dehydrogenation (HDH) and deoxidation in solid state (DOSS) processes. Each prepared powder was deoxidized with Ca contact and non-contact method to compare the deoxidation capability. It is known that the non-contact deoxidation method, using Ca vapor above the melting temperature $T_m$ of Ca, has greater deoxidation capability. However, Oxygen contents in Ti-6Al-4V and Ti-8Al-1Mo-1V powder after non-contact deoxidation method were higher than those after contact deoxidation method. Therefore, we investigate the effect of Al - the richest alloy element in theses Ti based metals - on the deoxidation processes.

• 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.27 no.1
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• pp.38-44
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• 2018

A large amount of Nd-Fe-B magnet scraps are generated during magnet manufacture process. In this study, selective chlorination of the rare earth elements by hydrogen chloride gas which obtained from the pyrolysis of polyvinyl chloride (PVC) was investigated. In thermogravimetric analysis, drastic weight loss was occurred at about 500 K and 710 K. At the isothermal experiments, the weight loss reaches about 30% above 673 K. XRD patterns characterized that after each experiments, ${\alpha}$-Fe, Nd oxychloride, Nd chloride, and Fe chlorides were formed, and the leaching residues remain only ${\alpha}$-Fe. The yields of Nd, Dy, and Fe for the isothermal experiment were increased with temperature and peaked at 873 K. As PVC ratio increased, the yields of Nd, Dy and Fe were also increased.

• Resources Recycling
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• v.27 no.5
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• pp.30-37
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• 2018

For recylcing of high purity tantalum (Ta) scrap, We investigated manufacture of tantalum powder using hydride-dehydride (HDH) process. Tantalum had excellent properties such as ductile, hardness and high melting point. Usually these properties made difficult to make a powder. In this study, Tantalum powder was manufactured using Tantalum hydride via hydridation. Tantalum hydride was formed at $500^{\circ}C$, 5 hr/$700^{\circ}C$, 3 hr and it is easy to make a tantalum hydride powder because hydrogen in the tantalum act as a defect dislocation and lattice expansion. The powder was pulverized to a size of less than $10{\mu}m$ under a condition of 1300 rpm, 30 min using a ring mill, and tantalum powder with less than 50 ppm hydrogen was prepared through dehydridation in an Ar and low vacuum atmosphere.

• Resources Recycling
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• v.14 no.2
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• pp.43-55
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• 2005

As world population increases and the world economy expalds, so does the demand for natural resources especially strategic metals such as cobalt. An accurate assesment of the nation's minerals must include not only the resources available in the ground but also those that become available through recycling. In this paper, data on domestic and international supply of cobalt and its applications by end-user were analyzed for stable security of cobalt resources and effective recycling of cobalt scraps. Also, an initial evaluation of the flow of cobalt-containing materials in the United States was prepared. In 2003, 8,000 metric tons of cobalt were consumed in the United States and an estimated 28% of U.S. cobalt supply was derived from scrap. The superalloy industry and catalyst industries have well-established recycling or cobalt recovery practices. Recycling rates of cobalt scraps from magnet alloy and cemented carbide were relatively low.