• Resources Recycling
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• v.25 no.3
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• pp.11-19
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• 2016

A fundamental study to recycle a Si-Sludge and waste copper nitrate solution acid solution generated by domestic electronic industries was carried out. The waste copper nitrate solution was used as the lixiviant to leach the metals like Cu, Ca, Fe, etc. from the sludge leaving Si in the residues. The effect of reaction temperature, time and pup density on the metals leaching from the sludge was investigated. To enhance the extractability of Fe, the effect of HCl, $HNO_3$ and $H_2O_2$ introduced additionally during the leaching was also examined. Considering the leaching efficiency of Fe along with Cu, the leaching conditions comprising of 200 ~ 225 g/L pulp density and $90^{\circ}C$ temperature for 30 min were optimized. Under this condition, 98.27 ~ 99.17% Cu could be dissolved in the leach liquor with the obtained purity of Si in the residues as 98.69 ~ 98.86 %. The study revealed that the leaching of Cu contained in the Si-Sludge with the waste copper nitrate solution is a plausible approach by which the obtained leach liquor can further be treated suitably to recover Cu as the high pure value-added products.

• Clean Technology
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• v.20 no.2
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• pp.136-140
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• 2014

The quaternary alloy (Co/Ni/P/Mn) coatings were prepared using electroless plating on the polypropylene. Compositions of the quaternary alloys (Co/Ni/P/Mn) were controlled by the amount of agents. The composition by EDS, morphology with SEM, film thickness, and surface electrical resistance of the samples were measured. Higher phosphorous content samples give larger electric resistance, thus a relationship is admitted between P content and electric resistance. The corrosivity of the coatings were evaluated by electrochemical methods in the 3.5 wt% NaCl and 5.0 wt% $H_2SO_4$ solutions, respectively. It was concluded that phosphorous addition enhances resistivity in the corrosion.

• Resources Recycling
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• v.5 no.1
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• pp.14-20
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• 1996

For recycl~ng alumhx~rn dross, the cbaraclcrislics of dross and ils reutll~zalin~af~te r plocsssing should he considered. Nurn~llumd ross was classified according to iB sire in this shldy. Tbe dross larger Illan 3001~1w as directly re-meltcd to recover aluminum, and the s~nallerd ~ossw as leachcd and riln~tedl o scparalc 111s eri~lerls alt and to oxidize the rnelals contained in the dross. As a rcwlt, amount of the dross uscd lo be dircarded ahcr processing could hc reduced Also, lhc chem~cal culnposit~ons of a domzstic alumlnum dross and the changes in con~posilii~ndsu ring processings were investigated. and Cound that most mctaU'ic aluminum in the dross was changed inlu alu~n~numox ide lhruugli the roasting. Tile processed dross would he ulillzed for malerials such as alumina, alumma cemenl or tilcs.

• Resources Recycling
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• v.33 no.4
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• pp.29-35
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• 2024

The recycling of waste resources, such as spent catalysts, primarily involves leaching and extracting metal components via smelting. These metal components are then recovered as salts, such as sulfates and nitrates. When crystallization occurs during the calcination of the recovered salts, the salts are converted into oxides, which are then reduced to form metals or ceramic materials. Common reducing agents used in oxide reduction include hydrogen and carbon, and metal powders are obtained upon reduction. Carbide synthesis can occur if the recycled element is a transition metal and carbon is used as the reducing agent. Despite being ceramic materials, transition metal carbides exhibit excellent conductivity owing to their metallic bonding. Recently, MXene, a two-dimensional transition metal carbide, has gained attention for electromagnetic wave shielding, secondary battery electrodes, and water purification owing to its electrical conductivity and large surface area. This study developed a process for synthesizing high-value MXene materials from waste resources. The properties of these MXenes were evaluated to confirm the potential of using waste resources as raw materials for MXenes.

• Tuberculosis and Respiratory Diseases
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• v.58 no.2
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• pp.167-173
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• 2005

Background : Airborne particles during Yellow Sand phenomena are known to be associated with the respiratory disease. The purpose of this study was to evaluate the concentration and metal component properties of Yellow Sand particles and compare with airborne microbial concentration and species in non Yellow Sand and Yellow Sand phenomena. Methods : Samplings were carried out in 2002 in Seosan, during non Yellow Sand and Yellow Sand phenomena. Samples were taken using the 8-stage Cascade impactor and metallic elements were analyzed by XRF. Those were culture on the media for bacterial and fungal culture and celline for virus. Results : The concentration of total suspended particulate matter were respectively $80.2{\mu}g/m^3$, $40.3{\mu}g/m^3$ in non Yellow Sand and Yellow Sand phenomena. The concentration of metallic elements such as Ca, Fe, Cu and Zn in Yellow Sand phenomena were higher than its in non Yellow Sand. Two bacteria, Bacillus species and Staphylococcus were grown in two periods. In both periods, several fungal spores(Mucor species, Cladosporum, Alternaria, Aspergillus, Penicillium, and Alternaria species) were identified. The differences of bacteria and fungus species not observed in Yellow Sand and non Yellow Sand. Any viruses were not isolated in between both periods. Conclusions : The concentration of total suspended particulate matter and some metallic elements in Yellow Sand phenomena were higher than its in non Yellow Sand. The difference of bacteria and fungus species was not observed in non Yellow Sand and Yellow Sand phenomena.

• Resources Recycling
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• v.27 no.1
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• pp.84-91
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• 2018

In this study, a novel soft information based most probable classification scheme is proposed for sorting recyclable metal alloys with laser induced breakdown spectroscopy (LIBS). Regression analysis with LIBS captured spectrums for estimating concentrations of common elements can be efficient for classifying unknown arbitrary metal alloys, even when that particular alloy is not included for training. Therefore, partial least square regression (PLSR) is employed in the proposed scheme, where spectrums of the certified reference materials (CRMs) are used for training. With the PLSR model, the concentrations of the test spectrum are estimated independently and are compared to those of CRMs for finding out the most probable class. Then, joint soft information can be obtained by assuming multi-variate normal (MVN) distribution, which enables to account the probability measure or a prior information and improves classification performance. For evaluating the proposed schemes, MVN soft information is evaluated based on PLSR of LIBS captured spectrums of 9 metal CRMs, and tested for classifying unknown metal alloys. Furthermore, the likelihood is evaluated with the radar chart to effectively visualize and search the most probable class among the candidates. By the leave-one-out cross validation tests, the proposed scheme is not only showing improved classification accuracies but also helpful for adaptive post-processing to correct the mis-classifications.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.37-40
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• 2005

폐 프린터의 발생량이 해마다 증가하고 있으며 이에 대한 재활용이 필요하다. 폐 프린터의 재활용에 있어서 다른 구성성분보다 기판의 처리가 문제가 된다. 본 연구는 폐 프린터의 기판을 재활용하는 데에 습식처리공정을 적용하기 위하여 먼저 전처리로 분쇄와 분리를 실시하였다. 기판을 1cm 이하로 분쇄한 다음 자력선별기를 이용하여 자성물질을 제거하고 비자성물질을 대상으로 4, 12, 40 mesh의 체를 이용하여 시료를 분리하였다. 전처리를 통하여 금속성분 특히 구리가 다량 함유된 12/40# 에 속한 시료를 대상으로 산에 의한 침출실험을 실시하였다. 실험 변수로는 산의 종류, 산 농도, 반응 온도, pulp density 등이었다.

• Journal of Welding and Joining
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• v.2 no.2
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• pp.1-6
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• 1984

피복아아크 용접봉(이하 용접봉이라 함)의 피복제는 염기도에 따라 산성, 중성, 염기성으로 대별할 수 있다. 용접에서의 화학야금반응은 제강의 화학야금반응과 원리는 비슷하나 양자간 크게 다른 점은 용접시의 반응시간이 극히 짧다는 점이다. 이와같이 반응시간이 짧다는 점 이외에도 작업자가 직접 용융반응을 지켜 보면서 반응후에 나타나는 제반 문제점에 대비하여야 하는 어려운 점이 있다. 제강반응은 전문가만의 독특한 기술인 반면 용접은 용접봉 제조자 뿐만 아니라, 용접작업자 고유의 기술이므로 용접야금반응을 상식화 하고자 하는데 본 고는 의의를 두고 있다. 피복제 중에서의 염기도의 변화, 즉 염기도에 영향을 크게 미치는 탄산칼슘의 양을 임의로 변화시키므로서 다음과 같은 현상을 기대할 수 있다. (1)용접 작업성의 변화 (2)용착 금속의 화학성분 변화 (3)용착금속의 조직 변화 (4) 용착금속내의 수소 함유량 변화 (5)용착금속의 기계적 성질변화 등이다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.493-495
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• 2010

• 대한예방의학회:학술대회논문집
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• 2000.10a
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• pp.31-32
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• 2000