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RISS 인기검색어
- 검색키워드
- 저자 : Kenneth N. Han (검색결과 17 건)
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Opportunities and challenges for treating rare-earth elements
Kenneth N. Han,Jon J. Kellar,William M. Cross,Sadegh Safarzadeh 한국자원공학회 2014 Geosystem engineering Vol.17 No.3
Rare-earth elements (REEs) have become an important group of metals used in various high-tech industries. In this paper, the authors have first reviewed and discussed various mineral-processing techniques used in the processing of these REEcontainingores. Because the majority of minerals from which REEs are extracted are monazite, bastnasite, and xenotime, the discussion has focused around the ores containing these three minerals. Following this discussion, various leaching technologies have been reviewed and problems associated with leaching technologies have been assessed again in the context of the afore-mentioned three minerals. The leaching technologies discussed here include leaching using various acids, and also leaching after acidic and alkaline roasting of the ores. Because of chemical similarities of these REEs, it is very difficult to separate the individual elements from each other. Various technologies used in this regard including chemical precipitation, ion exchange, and solvent extraction have been reviewed and discussed in detail. The effect of speciation of REEs in the solutions on the selective recovery has also been investigated.
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Han, Kenneth N. The Korean Institute of Resources Recycling 2001 資源 리싸이클링 Vol.10 No.5
Indium frequently associated with the semiconductor industry is becoming an important metal element widely used in industry. In this paper, its properties especially in relation to its recovery from scrap are reviewed and discussed. Also presented in this paper is how best indium can be recovered by the hydrometallurgical means.
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Effect of Temperature and Pressure on Equilibrium Constant Involving Metal Ions
Han, Kenneth N . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.6
The effect of temperature and pressure on the gibbs standard free energy formation of ionic species, hence the equilibrium constant involving these ions has been reviewed and discussed. The role of the partial molal volume on the equilibrium constant was reviewed first. It was found that the effect of pressure is negligible unless the pressure applied is excessive, say over 200 atmospheres. The Gibbs standard free energy formation of various metal ions in water at various temperatures has also been calculated using a conventional method as well as the correspondence principles. The temperatures considered were 60, 100, 150 and 200℃. The results obtained for these temperatures based on these methods have been compared and discussed. It has been found that the results by these two methods do not differ much' mostly within 5% which is contrary to what has been believed by many.
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Factors Affecting the Dissolution Behavior of Metals from Binary Alloys
Han, Kenneth N. The Korean Institute of Resources Recycling 2001 資源 리싸이클링 Vol.10 No.1
The strategy of recovering metals from scrap is in general much different from primary sources. One of the main differences between the treatment of scrap and that of primary sources lies with the fact that metals are frequently associated with other met-als to form alloys in scrap, while metals occur in primary sources as oxides or sulfides. In this paper, factors affecting the dis-solution behavior of metals from various alloy systems have been reviewed and discussed. Specific examples have been drawn from Au/Ag, Au/cu and Ag/cu systems. Results of the dissolution behavior of various metals from these alloys have been reviewed and compared to the dissolution behavior of single metal systems in various lixiviants such as acids, cyanide and ammonia. It has been observed that the presence of other metals in alloys would significantly affect the dissolution rate of the metal in question. The leaching behavior of metals from homogeneous alloys relies on the chemical interaction between atoms in the lattice of the alloys, while that from heterogeneous alloys is affected by galvanic interaction established in the solution The manner in which the dissolution of a certain metal is influenced by surrounding metals has been discussed in terms of pas-sive and noble nature of the metal in relation to the neighboring metals. The role of the standard electrochemical Potential of these metals on the selective dissolution for a given lixiviant has also been discussed.
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용해도 낮은 금속을 이용한 전기 전도성 잉크 원리 및 그 응용
한국남(Kenneth N. Han),김남수(Nam-soo Kim) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
In this investigation, various factors affecting manufacturing conductive inks are presented, examined and discussed. The discussion includes inherent difficulties in making conductive inks successful and at the same time offers ways in which these difficulties might be overcome. One of the solutions to overcome such difficulties is to use low melting metals and alloys. This aspect is also detailed.
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김남수(N. S. Kim),한국남(K. N. Han),Kenneth H. Church 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
나노크기의 입자를 수용액속에 분산시킨 나노잉크와 이를 이용한 직접인쇄방식 (Direct Write Technology)은 시간과 비용을 절약할 수 있고, 그 응용의 다양성과 소량다품종을 생산할 수 있는 장점으로 21세기에 들어서 주목받고 있는 기술이다. 직접인쇄방식은 RFID-Tag, Flexible-Electronics, OLED display, e-paper, 안테나, Flip-Chip용 범퍼(bumper), 언더필링(underfiling), Frit, 소형저항 및 생화학, 인공치아 등 그 응용부분이 광대하다. 이러한 다양한 응용분야로의 적용 가능성에도 불구하고, 직접인쇄방식은 재현성, 나노잉크의 점도, 입자크기, 재료 종류, 기판과의 접합성, 잉크 전기전도도, 화학적 안정성, 패터닝된 선의 분해능과 같은 물리화학적 특성과 적용 분야의 복잡성으로 인해 산업계에서 아직 활발하게 적용되어 지지 않고 있다. 본 연구에서는 직접인쇄방식 중 잉크 및 재료의 적용성에서 가장 호환성이 우수한 nScrypt사의 icro-Dispensing Direct Write(MDDW)기술의 한계와 가능성에 대해 조사하였다. MDDW기술은 나노잉크의 점도가 1~백만 cps까지 넓은 영역에서 사용 가능하여 여러 종류의 물질을 3차원 형상화 할 수 있으며, 직접 접촉식 방식으로 곡면 및 기판의 종류에 크게 영향을 받지 않는다. 그러나 다른 인쇄방식과 비교하여 미세한 선폭 10마이크론(um) 이하의 정확도로 패터닝하는 분야로는 적용에는 어려움이 있다. 또한 모든 직접인쇄방식이 갖고 있는 다양한 잉크와의 호환성은 개선되었으나, 잉크자체의 전기전도도 및 재현성에 문제가 있다. 본 논문에서는 현재의 MDDW로 가능한 시장분야와 새로운 나노잉크의 개발로 가능한 분야와 MDDW와 비교하여 기술적으로 상용화에 근접한 에어로-졸(Aerosol) 분사방식인 Maskless Mesoscale Materials Deposition(M3D)의 기술개발한계를 비교ㆍ검토하였다.
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Iodine/Iodide 용액에서 니켈의 용해 거동에 관한 연구
박형규,한국남 대한금속재료학회(대한금속학회) 1996 대한금속·재료학회지 Vol.34 No.5
The dissolution behavior of nickel in iodine/iodide solutions was investigated using a rotating disc. Experimental variables studied here included pH of the solution, temperature, concentration of lixiviants, and rotating speed of the nickel disc. Nickel easily dissolved when pH of the solution was about 2. However, the dissolution rate dramatically decreased when the pH of the solution became greater than 3. The dissolution rate increased at faster rotating speed, higher initial concentration of iodine, and temperature of the solution. The overall dissolution reaction rate was found to be influenced partially by surface chemical reaction and largely by mass transfer of triiodide through diffusion boundary layer at the liquid/solid interface with an activation energy value of 17.2 kJ/㏖. The possibility of reutilization of used iodine/iodide solution by electrowinning in an electrochemical cell was investigated and the results were promising.
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