• 한국세라믹학회지
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• 제52권2호
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• pp.92-102
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• 2015

Current plans for legacy nuclear wastes stored in underground tanks at the U.S. Department of Energy's Hanford Site in Washington are that they will be separated into high-level waste and low-activity waste fractions that will be vitrified separately. Formulating optimized glass compositions that maximize the waste loading in glass is critical for successful and economical treatment and immobilization of these nuclear wastes. Glass property-composition models have been developed and applied to formulate glass compositions for various objectives for the past several decades. Property models with associated uncertainties combined with composition and property constraints have been used to develop preliminary glass formulation algorithms designed for vitrification process control and waste-form qualification at the planned waste vitrification plant. This paper provides an overview of the current status of glass property-composition models, constraints applicable to Hanford waste vitrification, and glass formulation approaches that have been developed for vitrification of hazardous and highly radioactive wastes stored at the Hanford Site.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 Proceedings of The 6th korea-china joint workshop on nuclear waste management
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• pp.176-181
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• 2005

The electrolytic reduction process and the electrorefining process, which are being developed at the Korea Atomic Energy Research Institute (KAERI), are to generate molten waste salts such as LiCI salt and LiCI-KCI eutectic salt, respectively. Our goal in waste salt management is to minimize a total waste generation and fabricate a very low­leaching waste form such as a ceramic waste form. Zeolite has been known to one of the most desirable media to immobilize waste salt, which is water soluble and easily radiolyzed. Zeolite can be also used to the removal of fission products from the spent waste salt. Molten LiCI salt is mixed with zeolite A at $650^{\circ}C$ to form a salt-loaded zeolite, and then thermally treated in above $900^{\circ}C$ to become an immobilized product with crystal phase of $Li_{8}Cl_{2}$-Sodalite. In this work, a crystal phase changes of immobilization medium, zeolite, during immobilization of molten LiCI salt using zeolite A is introduced.

• 방사성폐기물학회지
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• 제18권4호
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• pp.509-516
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• 2020

An important property of glass and ceramic solid waste forms is processability. Tellurite materials with low melting temperatures and high halite solubilities have potential as solid waste forms. Crystalline TiTe3O8 was synthesized through a solid-state reaction between stoichiometric amounts of TiO2 and TeO2 powder. The resultant TiTe3O8 crystal had a three-dimensional (3D) structure consisting of TiO6 octahedra and asymmetric TeO4 seesaw moiety groups. The melting temperature of the TiTe3O8 powder was 820℃, and the constituent TeO2 began to evaporate selectively from TiTe3O8 above around 840℃. The leaching rate, as determined using the modified American Society of Testing and Materials static leach test method, of Ti in the TiTe3O8 crystal was less than the order of 10-4 g·m-2·d-1 at 90℃ for durations of 14 d over a pH range of 2-12. The chemical durability of the TiTe3O8 crystal, even under highly acidic and alkaline conditions, was comparable to that of other well-known Ti-based solid waste forms.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.472-478
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• 2018

In this study, the sintering mechanism of woodceramics (WCs) from cashew nut shell waste (CNSW) was studied by analyzing chemical reactions and structural changes during the sintering process of of CNSW powder, liquefied wood and green bodies of WCs at $900^{\circ}C$ for 60 minutes in the $CO_2$ atmosphere. The chemical and structural properties of the products were investigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared (FTIR), and scanning electron microscope (SEM). The results showed that the decomposition reactions of liquefied wood and CNSW occurred simultaneously to form the hard carbon and the soft carbon at high temperature. The sintering mechanism of WCs has been presented.

• 한국분말재료학회지
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• 제23권3호
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• pp.221-227
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• 2016

Waste oyster shells create several serious problems; however, only some parts of them are being utilized currently. The ideal solution would be to convert the waste shells into a product that is both environmentally beneficial and economically viable. An experimental study is carried out to investigate the recycling possibilities for oyster shell waste. Bulk ceramic bodies are produced from the oyster shell powder in three sequential processes. First, the shell powder is calcined to form calcium oxide CaO, which is then slaked by a slaking reaction with water to produce calcium hydroxide $Ca(OH)_2$. Then, calcium hydroxide powder is formed by uniaxial pressing. Finally, the calcium hydroxide compact is reconverted to calcium carbonate via a carbonation reaction with carbon dioxide released from the shell powder bed during firing at $550^{\circ}C$. The bulk body obtained from waste oyster shells could be utilized as a marine structural porous material.

• 동력기계공학회지
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• 제18권3호
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• pp.93-99
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• 2014

The purpose of this paper is to manufacture the non-sintered ceramic used lime and industrial waste. The used materials were basalt powder sludge, calcium hydroxide(Ca(OH)2) and additives such as calcium stearate and $TiO_2$. The mixing ratios between Ca(OH)2 and sludge were 5:5, 6:4 and 8:2, respectively. The ceramic forms were pressured by 100, 200 and 300 bar and cured in 14% CO2 for 12 days. The behaviors of compressive strength, specific gravity, water absorption and pH of ceramic form were investigated. The results were compressive strength of over 36 MPa, water absorption of over 8.8%, pH value of over 12.3. And these results satisfied GR F 4006 and 4031 standard.

• 한국세라믹학회지
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• 제39권6호
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• pp.576-581
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• 2002

원자력발전소에서 발생하는 이온교환수지와 잡고체를 동시에 처리하기 위하여 유도 가열식 저온용융로를 이용한 유리화 실증시험을 수행하였다. 유리 고화체의 화학적 내구성을 평가하기 위하여 최종 유리에 대해 수행한 PCT 침출 시험결과 기준유리 보다 내 침출성이 우수한 것으로 나타났다. 최종 유리 고화체에 대해 열처리 실험 결과 액상온도는 1048K (775$^{\circ}C$)로 측정되었다 유리 고화체에 대한 압축강도 측정 결과 규제치인 34kg/$\textrm{cm}^2$ 보다 약 90배 높은 값을 나타내었다. 저온용융로(CCM)의 하부, 중앙, 상부 유리 고화체의 미세구조 관찰 결과 이차상 없는 균질한 상태였다. 환원성 유기물을 함유한 이온교환수지에 잡고체를 동시 투입하여 자성 금속상 침전을 방지할 수 있었다. 유리화 실증시험을 통하여 감용비 74를 달성하였다.

• 자원리싸이클링
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• 제33권4호
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• pp.29-35
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• 2024

폐촉매 등 폐자원에 대한 재활용은 대부분 제련 공정을 통해 금속 성분을 침출 및 추출하는 과정이며 금속 성분은 황산염, 질산염과 같은 염 형태로 회수된다. 회수된 염에 대한 하소를 통해 염은 산화물로 변화하며 산화물은 환원 과정을 거쳐 금속 혹은 세라믹 소재가 된다. 산화물 환원 과정에서 사용되는 환원제는 수소, 탄소 등이 있으며 환원을 통해 금속 분말이 얻어지게 되는데 재활용된 원소가 전이 금속이고 탄소를 환원제로 사용하는 경우 탄화물 합성이 가능하다. 전이 금속 탄화물의 경우 세라믹 물질임에도 불구하고 금속 결합으로 인해 전도성이 우수한 것으로 알려져 있으며 최근 이차원 전이 금속 탄화물인 맥신(MXene)은 전기 전도성뿐 아니라 넓은 표면적이라는 구조적 특징으로 인해 전자파 차폐, 이차전지 전극, 수 처리용 소재로 주목받고 있다. 본 연구에서는 폐자원으로부터 고부가가치 맥신 소재를 합성하기 위한 공정을 개발하고자 하였으며 결과적으로 폐자원을 원료로 합성된 맥신의 특성을 평가하여 폐자원의 맥신 원료 적용 가능성을 확인하였다.

• 방사성폐기물학회지
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• 제17권3호
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• pp.313-319
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• 2019

A-KRS는 한국원자력연구원에서 개발한 파이로프로세싱 처리된 폐기물을 처분하는 개념이다. 고준위 방사성폐기물은 파이로프로세싱에 의하여 최소화되며, 최종 발생된 고준위 방사성폐기물은 모나자이트 세라믹 폐기물 형태로 제조된다. 모나자이트 세라믹 폐기물은 처분공에 영구 처분되어 열을 발생시킨다. 발생된 열은 폐기물을 보호하는 캐니스터 및 완충재의 온도를 상승시켜 설계 기준을 초과 시킬 수 있다. 온도는 처분공 간의 거리로 조절 가능하며 한국원자력연구원에서 해석한 바 있다. 한국원자력연구원에서 해석한 경계조건은 완벽 접촉을 가정한 것이기 때문에, 최초 처분 시에 발생하는 간격에 의해 발생하는 열 저항에 의한 온도 분포는 알 수 없다. 이를 보완하기 위하여, 본 논문에서는 최초 처분 시 존재하는 간격에 의한 열 전달 해석을 수행하였다. 또한 발열체와 캐니스터 간의 공극을 추가하여 온도 분포 해석을 수행하였다. COMSOL 전산해석 소프트웨어를 이용하여 열전달 해석을 수행하였다.

• 한국세라믹학회지
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• 제49권6호
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• pp.505-510
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• 2012

A study of the recovery of tin and nickel from steel ball scraps for barrel plating was carried out through a physical treatment, a leaching treatment, hydrogen reduction and an electrolysis experiment. The recovery of the iron component was over 95% by the physical treatment. We obtained tin oxide in the form of metastannic acid ($SnO_2{\cdot}xH_2O$) with impurities of less than 5% from the leaching treatment. We also recovered the high-purity metallurgical tin at a rate that exceeded 99.9% by the electrolysis of crude tin obtained from the hydrogen reduction of metastannic acid.