• 열처리공학회지
• /
• 제8권4호
• /
• pp.333-339
• /
• 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.

• 대한화학회지
• /
• 제30권1호
• /
• pp.63-68
• /
• 1986

양이온 교환수지를 이용하여 희토류 원소들의 용리현상을 연구하였다. 희토류 원소를 EDTA로 착물로 만들어 수지상단에 일정량 흡착 시킨 후 EDTA용액으로 용리하는 방법이 희토류 원소를 직접 양이온 교환수지에 흡착시키고 용리시키는 방법보다 희토류 원소들이 빨리 용리되어 용리액과 용리시간이 절약 되었다. 그러나 분리능은 약간 감소 하였다. 용리되는 순서는 착물의 안정도 상수가 큰 원소가 먼저 용리 되었다.

• 한국분말재료학회지
• /
• 제29권2호
• /
• pp.159-165
• /
• 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.

• 한국분말재료학회지
• /
• 제26권3호
• /
• pp.251-257
• /
• 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.

• 한국지구과학회지
• /
• 제34권4호
• /
• pp.289-302
• /
• 2013

대부분 니질 퇴적물로 구성된 황해 남동부 흑산니질대 퇴적물의 기원지를 밝히기 위해 퇴적물 시료에 대해 주성분 원소와 희토류 원소(REE)를 분석하였다. 표층 퇴적물 시료는 흑산니질대 내 51지점에서 피스톤식과 박스형 시료 채취기로 획득하였다. 흑산니질대의 표층퇴적물은 니 퇴적물이 우세하게 나타나며, 평균입도는 $5-6{\phi}$이다. 공간적으로 북쪽지역은 실트함량이 높고, 남쪽지역으로 갈수록 점토함량이 증가한다. 흥미롭게도 주성분 원소와 희토류 원소 함량 특성은 퇴적물 기원 해석에 있어 다른 결과를 가져왔다. Fe/Al과 Mg/Al 함량 비, $Al_2O_3$와 MgO 함량 비, $Al_2O_3$와 $K_2O$를 각각 도시한 결과, 흑산니질대 퇴적물은 한국 기원의 퇴적물이 우세한 것으로 나타났다. 하지만 희토류 원소의 특성은 중국 기원의 퇴적물이 우세함을 반영한다. 이러한 기원 불일치는 각 원소의 함량 조절요인이 다르기 때문이다. 주성분 원소는 입도와 높은 상관관계를 고려할 때 입도에 따라 그 함량이 영향을 받는 것으로 해석된다. 반면에 희토류 원소는 입도와는 상관관계가 낮으며, 중광물 함량에 의해 조절되는 것으로 사료된다. 이와 같이, 각기 다른 추적자에 따른 기원의 불일치를 해결하기 위해 추가적인 연구가 필요하다.

• 한국자기학회지
• /
• 제22권5호
• /
• pp.188-193
• /
• 2012

영구자석은 산업전반에 광범위 하게 쓰이고 있는 핵심 부품중의 하나이다. 이러한 영구자석을 만드는데 필수적으로 이용되고 있는 원소가 바로 희토류 계열의 원소들이다. 이미 널리 알려져 있는 것처럼 희토류 생산의 대부분은 중국이 차지하고 있고, 이러한 원인에 의해 전 세계적으로 희토류 원소의 생산 및 공급 불균형에 의해 발생하는 많은 문제점들을 인식하고 있다. 이를 해결하기 위해 희토류 기반 영구자석을 대체하기 위한 다양한 방안들이 논의 되고 있으나 현재까지 명확하게 희토류 대체 영구자석이 가능한 물질 혹은 구조에 대한 제시는 없다. 본 논문에서는 여러 가지 가능성 중에 교환스프링 자석구조에 대해서 논의하고자 한다.

• Journal of Applied Biological Chemistry
• /
• 제60권3호
• /
• pp.207-211
• /
• 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.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2004년도 학술논문집
• /
• pp.337-337
• /
• 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.

• 한국지구과학회지
• /
• 제42권4호
• /
• pp.383-389
• /
• 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.

• 에너지공학
• /
• 제27권2호
• /
• pp.61-69
• /
• 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.