• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.05a
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• pp.186-190
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• 2004

실리콘 잉곳의 절단공정에서 발생하는 폐슬러지는 실리콘과 실리콘카바이드 등의 유가자원이 함유되어 있으며, 이를 효과적으로 분리, 회수하는 방법에 대해 검토하였다. 폐슬러지에 함유된 오일은 유기 용매에 의해 용해되어 효과적으로 분리되었고, 불순물인 철분은 자력선별에 의해 제거할 수가 있었다. 또한 실리콘과 실리콘카바이드의 혼합 분말은 중액선별을 통하여 고순도의 실리콘과 실리콘카바이드로 분리할 수가 있었다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.87-88
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• 2022

The use of converter slag as an aggregate for concrete is limited due to the risk of expansion. This study analyzed the substances causing the expansion of converter slag and evaluated the possibility of its use as an aggregate for concrete through separation and selection. As a result of the experiment, it was confirmed that CaO and MgO were concentrated in the slag particles inducing expansion, and it was confirmed that it was possible to separate them from non-expanded particles through magnetic.

• Resources Recycling
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• v.16 no.3 s.77
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• pp.19-26
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• 2007

The bottom ash of municipal solid waste incineration generated during incineration of municipal solid waste in metropolitan area consists of ceramics, glasses, ferrous materials, combustible materials and food waste and so on. Although the ferrous material was separated by the magnetic separation before the incineration process, of which content accounts for about $3{\sim}11%$ in bottom ash. The formation of a $Fe_3O_4-Fe_2O_3$ double layer(similar to pure Fe) on the iron surface was found during air-annealing in the incinerator at $1000^{\circ}C$. A strong thermal shock, such as that takes place during water-cooling of bottom ash, leads to the breakdown of this oxidation layer, facilitating the degradation of ferrous metals and the formation of corrosion products and it existed as $Fe_2O_3,\;Fe_3O_4\;and\;FeS_2$. So, many problems could occur in the use of bottom ash as an aggregate substitutes in construction field. Therefore, in this study, the separation of ferrous materials from municipal solid waste incineration bottom ash was investigated. In the result, the ferrous product(such as $Fe_2O_3,\;Fe_3O_4,\;FeS_2$ and iron) by magnetic separator at 3800 gauss per total bottom ash(w/w.%) accounted for about 18.7%, and 87.7% of the ferrous product was in the size over 1.18 mm. Also the iron per total bottom ash accounted for about 3.8% and the majority of it was in the size over 1.18 mm.

• 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.

• Resources Recycling
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• v.10 no.3
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• pp.51-59
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• 2001

Impurities removal from waste carbon black was carried out to produce high-grade carbon black. A large amount of hydrophilic carbon black is produced as a byproduct of the hydrogen production process by flame decomposition of water. Due to its impurities content such as sulphur, iron, ash, etc., it can only be used as low-grade carbon or burnt out. High-grade hydrophilic carbon black is 3~5 times more expensive than oil-based carbon black because of high production cost associated with process complexly and pollutant treatment. Hydrophilic carbon is normally used for conductive materials for batteries, pigment for plastics, electric wire covering, additives for rubber, etc. In these applications, impurity content must be blow 1 fe. In this study, magnetic separation, froth flotation and ultrasonic treatment were employed to remove impurities from the low-grade hydrophilic carbon black. Results showed that the ash, iron and sulphur content of product decreased to less than 0.01 wt.%, 0.01 wt.% and 0.3 wt % respectively and the surface area of product was about 930 $m^2$/g for conductive materials.

• Resources Recycling
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• v.16 no.5
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• pp.71-76
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• 2007

The mixed plastic waste generated from households after hand-picking and/or mechanical sorting processes amounts to 1,750,000 ton in 2006, and most of these waste are finally end up with landfill and/or incineration due to the lacks of separation technologies and economical reasons. The mixed plastic wastes can not be used as raw materials for chemical and/or thermal recycling processes because of their high content of PVC(upto 4.0 wt.%). In the present research, gravity separation system has been developed to remove PVC from the mixed plastic waste and to recover the PO-type plastics. This system mainly consists of air classification, magnetic separation, one-step crushing, feeding system at fixed rate and wet-type gravity separation system. The gravity system based on centrifugal separation has been developed at capacity of 0.5 ton/h and it consists of mixing, precleaning, separation, dewatering, recovery system and wastewater treatment system, etc. The main objective of this process is to achieve high separation efficiency of polyolefins with less than 0.3 wt.% PVC content and less than 10% moisture content in the final products. In addition, a crushing unit of with 8 rotor system is also developed to improve the crushing efficiency of soft-type plastics. The system with a capacity of 1.0 ton/h is developed and operational results are presented.

• Resources Recycling
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• v.26 no.3
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• pp.32-38
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• 2017

For the massive recycling of mine tailings, which are an inorganic by-product of mining process, in the field of civil engineering, pretreatments to extract heavy metals are required. This study focuses on the use of pre-treated tailings as substitute fillers for controlled low-strength material (CLSM). As a comparative study, untreated tailing, microwave-treated tailing and magnetic separated with microwaved tailing were used in this study. Cement contents amounting to 10%, 20% and 30% by the weight of the tailings were designed. Both compressive strength and flowability for all types of mixture were satisfied with the requirements of the American Concrete Institute (ACI) Committee 229, i.e., 0.3-8.3 MPa of compressive strength and longer than 200 mm flowability. Furthermore, all mixtures showed settlements less than 1% by volume of the mix.

• Resources Recycling
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• v.13 no.5
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• pp.17-22
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• 2004

It has been carried our for establishing the methodology to upgrade $TiO_2$ by carbothermal reduction of iron oxide in ilmenite. Based on present experimental results, the possibility for substitution with rutile has been investigated. It could by proposed that the 2 wt.% $FeCl_3$ of sample and carbon of 2 equivalents are optimum conditions as a feeding materials. And also appropriate reducing temperature and reduction time were about $1100^{\circ}C$ and 30 minutes. The product obtained by the processes of carbon reduction and magnetic separation may be used the substitute mineral of rutile.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.122-123
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• 2003

물리적인 건식 방법으로 소각 및 매립되는 생활계 폐플라스틱에 포함된 이물질을 제거하는 공정을 확립 연구를 수행하였다. 수집 운반되는 생활계 폐플라스틱 시료의 발생 장소, 위치 및 시간에 따라 포함된 이물질 종류가 다르고 수분의 함량에 있어 차이가 많이 있어 투입되는 시료에 대한 일차 이물질 분석이 필요하다. 이물질 분리 공정은 운반 $\rightarrow$ 파쇄 $\rightarrow$ 선별 분리(자력, 와류, 스크린) $\rightarrow$ 저장의 순서로 진행하였으며 파쇄시 흙 종류가 많이 포함된 경우에는 -0.8cm로 파쇄할 경우 효과적이나 일반적으로 -1.2cm 정도로 파쇄하여 이물질을 선별 분리하여도 이물질이 함유량이 3%이하이며, 회수율은 97% 이상이었다.

• Resources Recycling
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• v.29 no.5
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• pp.15-27
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• 2020

Microplastics are recognized as critical and serious environmental problem in worldwide. Plastics are inexpensive, lightweight, excellent in processability, and various in material-specific properties. Along industrial development, the production and disposal amount of plastics are also rapidly increasing. In particular, abundant plastic wastes are eventually disposed into marine environment with harmful impacts on the ecosystem. Therefore, lots of relevant studies were recently progressed in various fields. However, many studies are being just conducted due to its difficulty in applying a general treatment method for those small particle sizes and their various characteristics. In the meantime, lots of researches are being conducted on applying methods using physical properties such as specific gravity, magnetic, and electrostatic separation, which are beneficiation processes of minerals. However, since it is still in the laboratory stage, the development of larger scale separation technology for efficient treatment is urgent.