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철도레일 부근 토양의 다환방향족 탄화수소 및 중금속 오염도 조사
최현경 ( Hyun-kyung Choi ),윤인주 ( In-ju Yoon ),신태천 ( Tae-cheon Shin ),김영훈 ( Young-hun Kim ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.11
Trains have been a major means of transport in Korea during these past decades. However, train facilities such as stations and repair shops are contaminated with organic and inorganic substances. There is a high probability of train facility contamination with polyaromatic hydrocarbons (PAHs). This study evaluated the PAH and heavy metal contamination of soil near railroads in the Kyungpook area. A total of 18 soil samples were collected from the railroads and analyzed for 16 PAHs and 6 heavy metal species. The contamination level of the top soil was found to be slightly higher than that of the subsoil for contamination with PAHs. The ratio of carcinogenic PAH concentration to the total PAH concentration was relatively high, with a maximum of 0.9. The toxicity equivalent (TEQ) of the PAHs were 500.6 ng/kg in the topsoil and 355.5 ng/kg in the subsoil. The ratio of low molecular PAHs (LPAHs) to high molecular PAHs (LPAHs) ranged from 6.7 to 29.5; this shows that contamination is primarily due to combustion of fuel rather than due to petroleum. The ratio of phenanthrene to anthracene and the ratio of fluoranthene to pyrene also show that contamination occurred due to combustion for transportation. The heavy metal contamination level was lower than the Korean standard, but higher than the background concentration; this indicates that the soil was affected by the operation of the railways.
논문 : 습식제련 ; Nd-Fe-B계 자석 스크랩으로부터 황산에 의한 Nd의 추출
이재천 ( Jae Chun Lee ),김원백 ( Won Back Kim ),정진이 ( Jin Ki Jeong ),윤인주 ( In Ju Yoon ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
A new process to extract Nd from domestic Nd-Fe-B magnet scraps was developed. The scraps were roasted in air and leached with H2SO4. The selective extraction of Nd was investigated in terma of roasting temperature, H2SO4 concentration, and leaching temperature and time. The increase in roasting temperature resulted in a significant reduction in the extraction rate due to the formation of FeNdO3. Nevertheless, Nd could be extracted more selectively since the extraction of Fe was retarded by the concurrent formation of Fe2O3 at higher temperatures. The selective extraction of Nd was observed to increase with shorter leaching time, lower H2SO4 concentration and leaching temperature. The solubility difference between FeSO4 and Nd2(SO4)3 was utilized to precipitate Nd as Nd2(SO4)3, which was separated as residue during the solid/liquid separation process after leaching. When scraps roasted at 700℃ was leached at the pre-determined optimum conditions(H2SO4 concentration: 4M, leaching temperature: 70℃, leaching time: 180 minutes, pulp density 100g/1) about 70% of Nd could be selectively separated as Nd2(SO4)3 precipitates. The Nd/Fe ratio in the precipitate was found to be about 18.33.