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Consideration of Diluents Selection and Input Amounts of the Hunter Process for Tantalum Production
Jae‑Jin Sim,Sang‑Hoon Choi,Yong‑Kwan Lee,Sung Gue Heo,Taek‑Soo Kim,Seok‑Jun Seo,Kyoung‑Tae Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
Tantalum (Ta) is a heavy refractory metal with an atomic weight of 180.95 g/mol, a density of 16.6 g/cm3, and a high meltingpoint of 3017 °C. With its refractory characteristics, it shows excellent chemical and physical stability as well as corrosionand heat resistance at elevated temperatures. The demand for Ta metal and related compounds is increasing with the expansionof the electronics and chemical industries. The Hunter process was proven to be effective in producing Ta powder in1953. Hunter proposed a method in which potassium heptafluorotantalate (K2TaF7) was reduced by sodium (Na). Thus far,this process has been the primary commercial method to produce Ta powder. In this study, quantitative differences wereanalyzed for diluent selection. Additionally, consideration was given to changes in the caloric value depending on the inputamount of diluents. Finally, the optimum material input and the properties of the prepared Ta were analyzed. Stoichiometricratios of K2TaF7(1 mol), NaCl (6.2–6.7 mol), Na (5–7 mol) were weighed, to perform a metallothermic reduction reaction. After the reaction, the tantalum powder was recovered and the flush process was carried out. After that, it was dried in avacuum atmosphere. Physical properties such as oxygen concentration, PSA, ICP-OES, and XRD of powder were conductedto evaluate the characteristics of Ta powder that was finally manufactured.
Choi, Dukhyun,Choi, Min-Yeol,Choi, Won Mook,Shin, Hyeon-Jin,Park, Hyun-Kyu,Seo, Ju-Seok,Park, Jongbong,Yoon, Seon-Mi,Chae, Seung Jin,Lee, Young Hee,Kim, Sang-Woo,Choi, Jae-Young,Lee, Sang Yoon,Kim, Jo WILEY-VCH Verlag 2010 ADVANCED MATERIALS Vol.22 No.19
<B>Graphic Abstract</B> <P>The cover shows an image of fully rollable transparent nanogenerators synthesized using chemical vapor deposition grown large-scale graphene sheets as transparent electrodes and piezoelectric ZnO nanorod arrays. Sang-Woo Kim, Jae-Young Choi, and co-workers report on p. 2187 the electrical and structural stability of the nanogenerators, with excellent charge scavenging performance under external mechanical loads such as bending and rolling. This study shows that graphene-based nanogenerators are very promising for self-powered rollable transparent device applications. <img src='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content.gif' alt='wiley_img_2010/09359648-2010-22-19-ADMA201090066-content'> </P>
Gasification Characteristics of Rapid Thermal Pyrolyzer Residue in a Fluidized Bed Reactor
Seo, Myung Won,Guahk, Young Tae,Rho, Nam Sun,Yoon, Sang Jun,Ra, Ho Won,Koo, Geon Hoe,Kim, Yong Ku,Kim, Jae Ho,Lee, Jae Goo,Kim, Sang Done American Chemical Society 2014 ENERGY AND FUELS Vol.28 No.5
<P>A novel process has been developed at KIER (Korea Institute of Energy Research) for upgrading extra-heavy oil fractions. This process uses a rapid thermal pyrolysis (RTP) of extra-heavy oil with a gasifier/combustor of RTP residue to produce syngas as well as to supply heat to the pyrolyzer. Unreacted carbon in RTP residues from the pyrolyzer are used as a feedstock to the gasifier/combustor. The RTP residue is mostly sand with 1 wt % of petroleum coke.The possibility that product gas from the gasifier/combustor can supply heat to the pyrolyzer is examined. A continuous fluidized bed reactor with the maximum capacity of 10 kg/h (0.05 m I.D. × 1.2 m high) was designed and constructed for RTP residue gasification/combustion. Air, oxygen, and steam were used as gasifying agents. The results of gasification are evaluated, including product gas composition, carbon conversion, gas yield, and heating value of the product gases. In air-blown gasification, the HHV (higher heating value) of the product gas ranges from 72.3 to 303.2 kcal/m<SUP>3</SUP>, which is lower than that of typical gasification. The carbon conversion is below 0.37, due to the low reactivity of petroleum coke and the diluting effects of nitrogen. In contrast, carbon conversion was greater than 0.93 with a higher equivalence ratio (ER = 1.0) in the O<SUB>2</SUB>-blown gasification mode. Product calorific values of up to 3739 kcal/m<SUP>3</SUP> can be obtained, with the steam serving as a gasifying agent.</P>
( Jae Hyuck Jun ),( Hyun Il Seo ),( Yang Hee Han ),( Jun Sung Kwon ),( Jong Kyu Park ),( Sang Jin Lee ),( Koon Hee Han ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1
Introduction: Amyloidosis is a group of diseases caused by abnormal deposition of insoluble amyloid fi brils in various tissues of the body. Diagnosis of gastrointestinal amyloidosis is difficult by reason of various symptoms and nonspecific endoscopic fi ndings. Here, we report a case of small and large intestine amyloidosis in multiple myeloma appeared as ischemic colitis. Case Report: A 67-year-old female was admitted due to hematochezia with abdominal pain. Immediate lower gastrointestinal endoscopy was done and showed necrotic colonic mucosa on transverse colon (fig. 1 A). Contrast-enhanced computed tomography revealed ischemic colitis with intramural hematoma (fig. 1 B). Thus,she had emergency right hemicolectomy for necrotizing ischemic colitis. After operation, she took ordinary postoperative care and discharged. After 1 month, she was admitted again due to abdominal pain and melena. There was no evidence of bleeding on upper gastrointestinal endoscopy. Lower gastrointestinal endoscopy revealed multiple ulcer of various size and shape in distal ileum and biopsy was done (fig. 1 C). Histopathologic exam exhibited green birefringence under polarized light microscopy (fig. 1 D). Therefore we could diagnose ileal amyloidosis. We reviewed surgically resected colonic tissue and had same result. Additional test, serum and urine protein electrophoresis, provided clues to multiple myeloma. Subseqent bone marrow biopsy confi rmed multiple myeloma. finally, we diagnosed intestinal amyloidosis in multiple myeloma which presented as necrotizing ischemic colitis. She took chemotherapy for multiple myeloma in oncology and has improved gradually until now 18 month after diagnosis. Conclusion: We report a case of a small and large intestinal amyloidosis fi rst presented with hematochezia and abdominal pain as typical ischemic colitis and showed necrotizing ischemic colitis in endoscopy. Gastroenterologist and endoscopist have to be aware of possibility of intestinal amyloidosis in case of ischemic colitis. Key word: Amyloidosis, Ischemic colitis, Hematochezia, Endoscopy.