• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.333-339
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• 1995

The reduction and diffusion process(R-D process) is an economical way to produce the functional materials which contain rare-earth elements and has been applied to the production of rare-earth magnet meterials($SmCo_5$, $Nd_{15}Fe_{77}B_8$), magneto-optical(MO) target materials and hydrogen storage alloy, etc. However, because of difficult to control of the final composition, the R-D process has not been applied to production of the 2-17 type rare earth permanent magnet materials which contain several elements. Therefore, this work was as a basic study for the production of the 2-17 type rare earth permanent materials with composition $Sm(Co_{0.72}Fe_{0.21}Cu_{0.05}Zr_{0.03})_{7.9}$ by the R-D process, the following were mainy examined ; the amount of metallic calcium as a reductant, homogenization condition of the alloy after the R-D reaction, masuring of magnetic properties of the sample after step aging. The sample prepared by the R-D process contained a little more oxygen than that prepared by the melting method, however, showed almost the same magnetic properties.

• Journal of the Korean Chemical Society
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• v.30 no.1
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• pp.63-68
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• 1986

Elution behavior of rare earth elements have been investigated with the EDTA solution as an eluent using cation exchange resin. Definite amount of the complexed rare earth ions at pH 8.4 is adsorbed through the cation exchanger containing cupric ion as a retaining ion and eluted with EDTA solution. The rare earth ions are eluted more rapidly in the above method than in the method in which uncomplexed rare earth ions are adsorbed on the cation exchange resin bed. In this method, the elution time and amount of eluent are saved but the resolution values also decreased a little. The elution order of complexed ion was determined in accordance with the stability constant of complexes with rare earth elements.

• Journal of Powder Materials
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• v.29 no.2
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• pp.159-165
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• 2022

Rare earth elements, which are important components of motors, are in high demand and thus constantly get more expensive. This tendency is driven by the growth of the electric vehicle market, as well as environmental issues associated with rare-earth metal manufacturing. TC 298 of the ISO manages standardization in the areas of rare-earth recycling, measurement, and sustainability. Korea, a resource-poor country, is working on international standardization projects that focus on recycling and encouraging the domestic adoption of international standards. ITU-T has previously issued recommendations regarding the recycling of rare-earth metals from e-waste. ISO TC 298 expands on the previous recommendations and standards for promoting the recycling industry. Recycling-related rare earth standards and drafts covered by ISO TC 298, as well as Korea's strategies, are reviewed and discussed in this article.

• Journal of Powder Materials
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• v.26 no.3
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• pp.251-257
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• 2019

Since the ISO decided to deal with rare-earth elements at the $298^{th}$ Technical Committee (TC) in 2015, Korea has participated in four plenary meetings and proposed four standards as of June 2019. The status of ISO TC 298, the standards covered by the TC, and the standardization strategies of Korea are summarized. Korean delegations are actively engaged in WG2, which deals with recycling, proposing four standards for fostering the rare-earth recycling industry. However, the participation of domestic experts is still low compared with the increase in the number of working groups and the number of standards in TC 298. The aim of this article is to summarize the current status of ISO international standards related to rare-earth elements, to encourage relevant experts to participate in standardization, and to develop international standards that accurately reflect the realities of the industry.

• Journal of the Korean earth science society
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• v.34 no.4
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• pp.289-302
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• 2013

In order to determine the provenance of the Huksan Mud Belt sediments in the southeastern Yellow Sea, the major and rare earth elements of the same sediments were analyzed. The surface sediments were sampled from top of piston-cores and box-cores taken at 51 sites within the Huksan Mud Belt. With the mean grain size of $5-6{\phi}$, the sediments of the study area are mud-dominated. The spatial distribution patterns show that silt content is high in the northern Mud Belt, whereas clay content increases as it moves toward the southern Mud Belt. Interestingly, the geochemical compositions both of major and rare earth elements have resulted in differences of sediment provenance. Among the major elements, plots of Fe/Al vs. Mg/Al ratios, $Al_2O_3$ vs. MgO ratios, and $Al_2O_3$ vs. $K_2O$ reveal that the Huksan Mud Belt sediments are dominated by the Korean river-derived sediments. However, the characteristics of rare earth elements infer sediments originating from the Chinese rivers. This discrepancy between the above provenances is attributed to the different contributory factors in the content of chemical elements. Considering strong correlation between major elements with grain sizes, the contents of the major elements are thought to be influenced by the grain size. However, there is a weak correlation between rare earth elements and grain sizes. The behaviour of rare earth elements may be controlled by heavy minerals, rather than grain sizes. Further study requires to solve the discrepancy arose from the difference in applied chemical tracers.

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.188-193
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• 2012

Permanent magnet is one of the most important parts in modern industry and the rare earth elements play an essential role for operation of permanent magnet. As is well known, the rare earth elements are mostly produced in China and the world is now facing serious problems owing to supply and demand imbalances. Many attempts have been performed to replace these rare-earth based permanent magnets by rare-earth free magnets, but they have not been successful so far. Regarding this issue, we discuss about an exchange spring magnet as a potential rare earth free permanent magnet structure.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.207-211
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• 2017

It is introduced an outstanding book about an important topic in occupational and environmental sciences i.e., the opportunities and challenges that may be connected with increasing the use and distribution of rare earth elements. These chemically similar elements, comprising the lanthanides, scandium, and yttrium, are involved in a number of essential technological applications, and their effects raise a number of human health issues of relevance to the occupational and environmental sciences. The book that I introduced here, "Rare Earth Elements in Human and Environmental Health; At the Crossroads between Toxicity and Safety" edited by Giovanni Pagano (Pan Stanford Publishing Pte. Ltd., Temasek Boulevard, Singapore) represents a break from that situation. It is essential to increase our knowledge about the environmental fate and biological effects of these technologically important metals in order to prevent unforeseen long-term man-made consequences to human health. This book is likely to become an important resource for scientists, engineers, and decision makers who understand the need for sensible exploitation of this resource.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.337-337
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• 2004

As one of researches for the P ＆ T purposes, a basic experiment on the recovery of actinide elements from the mixture with rare earth elements by means of electrorefining using a liquid cadmium cathode in the LiCl-KC1 eutectic melt was carried out. In order to examine the behaviors of electrodeposition of metal ions on a liquid electrode, recovery experiments of rare earth metals resulting from forming electrodeposits were performed by a galvanostatic electrolysis method at various current densities. A cyclic voltammetric technique was applied to determine reduction-oxidation potential of each metal element in the melt and to detect the changes of the multi component melt composition for on-line monitoring. Also, a collaboration study with RIAR was completed to test the preliminary feasibility on a recovery of actinide elements from the mixture with rare earth elements using a liquid cadmium cathode and actinide metals. Experimental results showed that the ratio of actinides to rare earths, 9: 0.5∼1 led to the rare earth content of about 5∼10 wt% in the deposit.

• Journal of the Korean earth science society
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• v.42 no.4
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• pp.383-389
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• 2021

Several studies investigating the behavior and environmental distribution of rare earth elements (REEs) have been reviewed to determine the geochemical processes that may affect their concentrations and fractionation patterns in groundwater and whether these elements can be used as tracers for groundwater-rock interactions and groundwater flow paths in small catchments. Inductively coupled plasma-mass spectrometry (ICP-MS), equipped with an ultrasonic nebulizer and active-film multiplier detector, is routinely used as an analytical technique to measure REEs in groundwater, facilitating the analysis of dissolved REE geochemistry. This review focuses on the distribution of REEs in groundwater and their application as tracers for groundwater geochemistry. Our review of existing literature suggests that REEs in ice cores can be used as effective tracers for atmospheric particles, aiding the identification of source regions.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.61-69
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• 2018

Rare earth elements together with Y and Sc (REEs) are essential in the development of technology for clean and efficient use of energy. In recent years coal deposits have much attention and attracted as a promising alternative raw sources for rare earth elements, not only because the REEs concentrations in many coals or coal ashes are equal to or higher than those found in conventional types of REEs ores but also because of the world wide demand for REEs in recent years has been greater than supply. In the coal ashes, REEs are mainly associated with carbonates, silicates and aluminosilicates in ashes at 800 and $1100^{\circ}C$. These elements are known to be powerful environmental tracers in natural biogeochemical compartments. In this study, to reviewed the REEs originating and distribution patterns in coal ash samples from the bedrock and/or soil weathering that were entrapped by lichens and mosses was investigated. The REEs patterns of different organisms species allowed minor influence of the species to be highlighted compared to the regional lithology.