• Resources Recycling
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• v.11 no.2
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• pp.28-35
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• 2002

A study on the grinding characteristics of metal components in printed circuit boards (PCBs) scrap by a swing-hammer typeimpact mill was conducted. The PCBs scrap crushed to sizes less than 3 mm were pulverized to liberate metal components by the impact mill. The effect of rotation speed of hammer on the grinding characteristics was investigated. The particle size distribution and degree of liberation of metals such as copper and solder were measured. The effect of rotation speed and particle size on the shape sorting of metal Particles from milled PCBs was investigated using an inclined vibrating Plate. At the hammer speed of 61.3 m/s about 80% of the copper particles became larger than 297 $\mu$m while 90% of solder particles was smaller than 297 $\mu$m. In the shape sorting method, the recovery location becomes shorter as the rotation speed of hammer increases. The recovery location for particles larger than 297$\mu$m was shorter than for particles sized between 149$\mu$m and 297$\mu$m. As the recovery location becomes shorter, KI value increases towards unity while $\phi_{c}$ value decreases towards unity indicating the more roundness of metal particles.

• Analytical Science and Technology
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• v.16 no.2
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• pp.143-151
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• 2003

In the present study, we made measurements of PM-bound metal concentrations from seven different urbanized locations in Seoul for the period covering March 2001 through May 2002. The measurement data were analyzed to explore the possible influences of spatial factors on metal distribution characteristics. To check for the importance of such aspects on metal distribution characteristics, the measured data were compared between different metals and between different sites by several criteria including (1) coefficient of variation (CV) values; (2) temporal variability; and (3) the abundance of strongly correlated pairs. The overall results of our study indicate strong diversity in the distribution characteristics of different metals. It is found that some metals (like Fe, Mn, and Pb) tend to exhibit strong compatibility among different study sites. However, no such compatibility appears to exist for certain metals like Cu. To account for the importance of spatial factors, complex relationships between source/sink processes and geochemical characteristics of a given metallic component may have to be examined in a systematic manner.

• Environmental engineer
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• s.123
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• pp.42-43
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• 1996

중금속을 함유하는 폐수는 일반적으로 단일성분의 원소로 되어 있지 않고 여러 종류의 금속성분이나 유기물이 혼합된 상태로 발생되기 때문에 화학적인 중화나 분해로서 처리하기 곤란하므로 흡착성이 풍부한 광물질의 무기화학성분을 추출하여 흡착, 침전, 분리하는 방법을 이용할 수 있다. Aqua # 219는 폐수 처리용 약품으로 현재 사용하고 있는 설비를 일부 개조하거나 또는 기존설비를 그대로 사용하여 저렴한 가격으로 처리할 수 있는 중금속 흡착제이다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.379-380
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• 2003

연소나 폐기물 감량화 처리를 위해 이루어지는 소각과정에서 방출되는 대기오염물질은 소각재의 다양한 특성으로 인해 배출물의 특성파악이 매우 어렵고 그로 인해 제어에 많은 어려움을 겪고 있다. 연소 혹은 소각과정에서 에어로졸을 제어하는 것은 대기 중에서 발견되는 중금속성분을 근본적으로 줄이는 기본적인 조치로서 상당히 중요한 역할을 한다(Natusch and Wallace, 1974; Oppelt, 1986; Oberdorster et al., 1995). 본 연구에서는 소각공정에서 금속성 에어로졸 형태로 배연기체 중에 혼합되어 배출되는 여러 가지 금속성분 중 양적으로 많이 배출되는 납성분의 제어를 위한 기초연구를 수행하였다. (중략)

• Resources Recycling
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• v.5 no.3
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• pp.37-43
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• 1996

The recovery of metals from printed circuit board(PCBs) scraps was investigated by utilizing a shape sorting method.After all electronic parts mounted on the board were removed. PCBs were pulverized to particles smaller than 1 mm by aswing hammer type impact mill in order to liberate metal components. Metals were separated from nonmetalliccomponents by an inclined vibrating plate (IVP). The metal separation efficiency was measured as a function of vihrationintensity and inclined angle. The maximum efficiency was obtained when IVP was operated at the vibration intensity(Kv)of 1.40 and the inclined angle of 10". The grade of the metal components was recovered from PCBs exceeding 90% byusing IVP.0% by using IVP.

• Resources Recycling
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• v.24 no.3
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• pp.76-80
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• 2015

Mobile phone has become one of the essential items in our daily life. In Korea, it is estimated that more than 20 million cell phones are discarded each year due to advancement in technology, thus creating disposal and environmental pollution. In order to conserve the resources, their proper recycling is essential as it contains both valuable and toxic metals. The economics of the recycling will depend on the amount and value of the metals. Therefore, it is necessary to determine the composition of the metals present in the different cell phones. In the present study, a report is presented on the variation of metal content per year of waste mobile phones. A review has been made for the mobile phones manufactured during the period 2000-2009 and metal content of the printed circuit boards (PCBs) by analyzing their metals. An example of the precious metal palladium and of the heavy metal lead shows the decreasing trend.

• Conservation Science in Museum
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• v.28
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• pp.89-108
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• 2022

Among about 500,000 characters in metal types in National Museum of Korea, this study conducts a statistical analysis of 62 metal types from the early Joseon Dynasty, including 33 gabinja (甲寅字) types and 29 eulhaeja (乙亥字) Hangeul types by examining the shape, measuring the specific gravity, and identifying the components based on previously-studied Joseon metal types. Among them, 33 gabinja types and 24 eulhaeja types were made of two-component bronze (copper and tin) (Group A), and four eulhaeja types were produced with three-component bronze (copper, tin and lead). (Group B), and one eulhaeja type was created with two-component bronze (copper and tin) with a high tin content (Group C). By comparing with imjinja (壬辰字) types of the late Joseon Dynasty based on multiple statistical analyses of type components, this study confirms that late-Joseon types have low copper content and high zinc and lead content, and therefore it may be possible to distinguish between the types of early and late Joseon Dynasty.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.165-166
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• 2000

가막만은 반폐쇄성 해역으로 해수의 유통이 잘 되지 않고 주변에 여수시의 생활하수가 유입되는 곳이다. 또한 양식어장 증가 및 화학공장의 건설 등 다양한 오염원의 증가로 만 북부에서는 하계에 빈산소 현상이 주년 나타나고 있어 수산피해가 우려된다. 본 연구의 목적은 표층퇴적물과 주상 퇴적물에 함유된 유기물과 금속성분을 분석하여 각 성분의 지화학적 특성을 이해하고 이들 물질의 오염원 분포 및 강도를 추정하는데 있다. (중략)

• Resources Recycling
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• v.19 no.3
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• pp.9-15
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• 2010

Domestic gold mine tailings, generally, contain a lot of non-metallic silica and clay minerals. These minerals can be separated from the tailings by various physical separation methods and used as raw materials for cements and ceramic products. In these physical separation procedures, metallic complex sulfides, in which Au and metallic constituents such as Pb, As and Fe were concentrated, were obtained as a by-product. These metallic constituents should be removed or separated from the by-product to extract Au efficiently. In this work, removal and separation processes of Pb, As, and Fe from the by-product were investigated. Pb was removed to under 3% by using alkaline oxidative leaching at the leaching condition of $120^{\circ}C$, 2M NaOH, 100psi $Po_2$, 250r.p.m., 4 wt.% solid and 30 min. leaching time. The leached residue was roasted and separated magnetically to obtain a non-magnetic product contained <0.2% As, <3% Fe and high concentrated Au more than 8,000 ppm.

• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.73-86
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• 1999

The ion-exchange method for the purification of primary coolant has been used broadly in PWR(pressurized water reactor)-type nuclear power plants due to its high decontamination efficiency, simple system, and easy operation. However, its non-selective removal of metal and non-radionuclides shortens its life, resulting in the generation of a large amount of waste ion-exchange resin. In this study, the feasibility of electrodeionization (EDI) was investigated for the purification of primary cooling water using synthetic solutions under various experimental conditions as an alternative method for the ion exchange. The results shows that as the feed flow-rate increased, the removal efficiency increased and the power consumption decreased. The removal rate was observed as a 1000 decontamination factor(DF) at a nearly constant level. For the synthetic solution of 3 ppm TDS (Total Dissolved Solid), the power consumption was 40.3 mWh/L at 2.0 L/min of feed flow rate. The higher removal rate of metal species and lower power consumption were obtained with greater resin volume per diluting compartment. However, the flow rate of the EDI process decreased with the elapsed time because of the hydrodynamic resistivity of resin itself and resin fouling by suspended solids. Thus, the ion-exchange resin was replaced by an ion-conducting spacer in order to overcome the drawback. The system equipped with the ion-conducting spacer resolved the problem of the decreasing flow rate but showed a lower efficiency in terms of the power consumption, the removal rate of metal species and current efficiency. In the repeated batch operation, it was found that the removal efficiency of metal species was stably maintained at DF 1000.