• Resources Recycling
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• v.24 no.4
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• pp.32-37
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• 2015

Cobalt is abundant only in some countries including Democratic Republic of the Congo. It would be necessary to secure overseas Co ores and Co extraction technology. Two kinds of matte varying the sulfur content were manufactured by smelting reduction of Co concentrate containing ~8 wt% Co, ~19 wt% Cu, and ~3 wt% Fe. The amount of Co, Cu and Fe was concentrated to 19~21 wt%, 39~41 wt%, and 7~9 wt% respectively in the resulting matte. High-pressure leaching of matte was performed in an autoclave with considering the effect of oxidizing agent, $H_2SO_4$ concentration as a lixiviant, and the amount of sulfur added to the matte. An oxidizing agent (oxygen) is necessary to improve Co leaching efficiency enabling usage of a dilute $H_2SO_4$ leaching agent. An increase in $H_2SO_4$ concentration prevents selective leaching of Co, and the sulfur content in matte has a minor influence on the Co leaching efficiency.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.413-416
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• 2004

매립장 침출수로 인해 오염된 매립장 주변 지하수 정화를 위한 실내실험을 실시하였다. 오염물로는 대표적 염화용제인 TCE와 PCE, 그리고 중금속인 As, Cd, Cr, Pb에 대하여 Air-sparging, 오존 산화법, 화학적 처리방법에 의한 정화효율 실험을 실시하였다. Air-sparging은 TCE, PCE에서 높은 제거효율을 가졌으며, 오존 산화법은 Cr, Pb에서 제거 효율이 좋았다. 반응제를 첨가한 공침방법의 경우, 모든 중금속에 대하여 소석회 첨가시 매우 높은 제거효율을 보였으며, As는 황산제일철에서, Cd, Cr, Pb는 탄산칼슘과 제올라이트 첨가시 높은 제거효율을 나타내었다. 실험결과로부터, 유기오염물과 중금속이 혼합되어 나타나는 매립장 주변 오염 지하수의 경우 휘발성 유기오염물의 제거를 위해서는 폭기방법이, 중금속의 경우에는 공침방법에 의해 수산화물, 탄산염으로 만들어 고형물로 처리하는 방법이 제거효과가 좋은 것으로 나타났다.

• Economic and Environmental Geology
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• v.36 no.2
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• pp.123-131
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• 2003

Geophysical surveys(electrical resistivity, self-potential, seismic refraction, GPR) were conducted to investigate the physical properties of the subsurface, and to delineate the flow channel of leachate from a AMD(acid mine drainage), buried rock wastes and tailings, and drainage pipes at an abandoned mine(Kwangyang mine). Especially in rainy season the sites appear to be abundant in AMD leachate, characterized by electrical conductivities of 0.98-1.10 ms/S. Electrical resistivity sections indicate that the leachate flows running in two directions at southern part rise up through the narrow fracture zones at the central part and contaminates the surrounding soil and stream. Such schematic features at the anomalous zone are well correlated with negative peaks in self-potential data, the limited penetration depth in GPR data and low velocity zone in seismic refraction data. Shallow high-resistivity zone is associated with the buried rock wastes which cause the diffractions in GPR image. In addition, the events at depth of approximately 1-1.25 m in GPR sections must be the metal pipes through which AMD is drained off to the inner bay.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.3
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• pp.211-221
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• 2016

Waste salt generated from a pyro-processing for the recovery of uranium and transuranic elements has high volatility at vitrification temperature and low compatibility in conventional waste glasses. For this reason, KAERI (Korea Atomic Energy Research Institute) suggested a new method to de-chlorinate waste salt by using an inorganic composite named SAP ($SiO_2-Al_2O_3-P_2O_5$). In this study, the de-chlorination behavior of waste salt and the microstructure of consolidated form were examined by adding $B_2O_3$ and $Fe_2O_3$ to the original SAP composition. De-chlorination behavior of metal chloride waste was slightly changed with given compositions, compared with that of original SAP. In the consolidated forms, the phase separation between Si-rich phase and P-rich phase decreases with the amount of $Al_2O_3$ or $B_2O_3$ as a connecting agent between Si and P-rich phase. The results of PCT (Product Consistency Test) indicated that the leach-resistance of consolidated forms out of reference composition was lowered, even though the leach-resistance was higher than that of EA (Environmental Assessment) glass. From these results, it could be inferred that the change in the content of Al or B in U-SAP affected the microstructure and leach-resistance of consolidated form. Further studies related with correlation between composition and characteristics of wasteform are required for a better understanding.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.771-779
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• 2020

This study was performed to develop a priority list for post-managements of leachates from 64 mine waste dump sites in Korea. For this, leachate quality, leachate quantity, and other factors were considered as evaluation criteria and the weights of 10 subfactors were calculated using Analytic Hierarchical Process (AHP) based on a survey from 20 experts in the field of mining environment. Calculated weights were 0.769, 0.147 and 0.084 for leachate quality, leachate quantity, and others, respectively, indicating that experts consider leachate quality as most important. Based on this approach, we classified the 64 mine waste dump sites into five grades from Grade I to Grade V. Ten were classified as Grade I, 1 as Grade II, 1 as Grade III, 33 as Grade IV, and 19 as Grade V.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2002.05b
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• pp.247-248
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• 2002

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.11a
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• pp.239-240
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• 2008

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.171-177
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• 2007

In order to investigate the effect of the methanogenic bacteria in bacteria in leachate on the degradability of landfill waste, this study has created 4 cylinder-shape PVC lysimeters (Diameter: 30cm, Height: 200cm, Volume: 140L) and for the biological treatment and recirculation of the leachate, two anaerobic batch reactors (Diameter: 20cm, Height: 30cm) were created. To simulate a conventional landfill, no recycling was done in L1. In L2, 1,068ml of leachate (twice of rainfall amount) was recycled. In L3 and L4, the leachate was anaerobically digested in a dark room (with $35{\pm}1^{\circ}C$) for a week and them recycled by 1,064ml and 2,128ml, respectively, with recycled water only. In terms of cumulative $CH_4$ production, however, L3 and L4 were much higher (three times) than L1 and L2. Between L3 and L4, the latter was 1.23 times higher than the former in terms of cumulative CH4 production. In other words, the more the methanogenic bacteria-activated leachate is recycled, the more active the degradation due to active methane fermentation by the recyled methanogenic bacteria. And methane recovery is different according to the amount of recycled the methanogenic bacteria in leachate.

• Applied Biological Chemistry
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• v.13 no.1
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• pp.73-79
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• 1970

The present study has been undertaken to see if any proper measure be found for the determination of available phosphorus by chemical extraction on the basis of A-values as the standard. The results obtained are described as follows. 1. Since A-value of the samples under study showed a significant correlation with Fe-P at 1% level. The available phosphorus in the present paddy soils was considered to be affected by Fe-P. 2. Six methods for chemical extraction were not correlated with the determination of Fe-P, proving them inadequate for the quantitative measurement of available phosphorus. 3. Adequate method for extracting available phosphorus in paddy soils should rest on the measurement of the reduction intensity of Fe-P. The extractable intensity was estimated to be 270 ppm in average. 4. Bray No. 2-P showed significant correlation with Lancaster-P, Spurway-P, Truog-P, and (Ca+Al)-P at 5% level. Olsen-P and Lancaster-P indicated significant correlation with Al-P and Spurway-P with Ca-P respectively at 1% level.

• The Korean Journal of Food And Nutrition
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• v.16 no.1
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• pp.46-53
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• 2003

Panax ginseng leaf tea was developed for the functional benefit of health, preference and convenience. The leaves of 4-year-old ginseng were selected in July and August. The ginseng leaf was treated by three methods : heat processed tea(HPT), aged tea(AGT) and hot-air dried tea(DRT). The contents and compositions of their crude saponin of ginseng leaves were measured. 1. The content of crude saponin of HPT was the higher than other treatments. The content of HPT was 18.72∼18.82％, ACT 18.24∼18.29％ and DRT 17.02∼17.17％. 2. The harvest time and treatment methods were not affect the composition of ginsenoside in ginseng leaf tea. The ginsenoside-Re was shown the highest value as 1.97∼2.15. And ginsenoside-Rd was 1.48∼1.79, -Rg$_1$ 1.33∼1.58 and -Rb, -Rb$_2$, -Rc in the order. 3. The content of protopanaxadiol(PD) and protopanaxatriol(PT) was shown that DRT was 1.11∼1.13, HPT 1.09～l.12 and AGT 0.92∼1.02. The content of PD and PT were shown similar result at any harvest time. 4. The contents of crude saponin extracted by hot-water at 5 min was the higher ratios in HPT and harvested in July than other treatments. The content of crude saponin of ginseng leaf harvested in July was 15.88% and HPT was 16.88%. The order of contents of ginsenoside were -Re, -Rd, -Rg$_1$, -Rb$_1$, -Rb$_2$, and - Rc. The extraction ratio of crude saponin extracted by the circulated extraction method in 8 hours and 5 min extraction were 81.74∼84.38％. And HPT of ginseng leaf harvested in July was the highest value 84.3％ but the extraction ratio of ginsenoside was 78.00～88.13%. But the extraction ratio of ginsenoside was similar trend in all treatments.