미쯔비시 동 제련 로에서 Cu 제련 공정에서 사용하는 랜스 수명 연장에 대한 연구

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 재료공학부, 2021. 2. 이경우.Smelting is the first step in the Mitsubishi continuous process for Cu production, resulting in the production of 68% copper matte and Fe-silicate slag. One of the main issues pertaining to the smelting furnace is the frequent interruption of operations required to allow the inspection and replacement of lances since lances are frequently fractured. First, the present study was aimed at modifying the operating conditions of the smelting furnace to suppress lance fractures. A numerical model was developed to simulate the transport phenomena including multi-phase behaviors in the furnace. The simulation results showed that the lances were exposed to a severely erosive atmosphere with high temperatures. Further calculation indicated that raising the positions of the lances could lower the temperature of the lances, and reduce the occurrence of splashed melt, which contains erosive sulfides. This condition was applied and observed in the field operation. It was confirmed that by implementing such a change of the lance heights, the occurrence of lance failures had been considerably reduced without notably affecting the reaction ability of the smelting furnace. Additionally, modifying the feeding system was suggested that feeding continuously as a method of stabilizing the interior of smelting furnace during the process because the effective reactivity could be increased. Second, investigation of lances used in field operations, thermodynamic analysis and laboratory experiments were conducted for studying the reaction mechanism. By analyzing the lances, the surface of the lances was damaged and penetration of matte components into the lance was observed and the damage occurred to a certain height. Since the lance temperature varies depending on the height, we could estimate that damage on the lance is directly related to the temperature. Therefore, thermodynamics calculations were conducted and Cu-Fe alloy existed as a liquid phase at approximately 1100℃. Based on the experimental results, laboratory experiments were conducted and liquid copper was also produced at above 1100℃. From these results, it can be considered that temperature above 1100℃ can cause the lance fracture and part of the lance located at higher temperature than 1100℃ can be deteriorated and finally fractured. Thus, during the Mitsubishi process, when the lance is kept at a temperature below 1100 in the furnace, surface damage can be reduced and the lance life-time can be increased. Through the present study, a numerical model within the S-furnace was developed and we suggested conditions to reduce the fracture of lance using this model. From microstructure analysis of lance, we found out the mechanism by which lance fracture occurs, and confirmed that maintaining the lance tip below 1100℃ can result in stable conditions for increasing lance life-time.Contents Abstract..........................................................................................................Ⅰ Contents........................................................................................................ Ⅳ List of Figures................................................................................................. Ⅷ List of Tables.................................................................................................. XV Chapter 1. Introduction.................................................................................. 01 Smelting furnace in Mitsubishi process.................................................... 01 Fracture of lance in S-furnace...................................................................05 Previous studies for the S-furnace............................................................ 07 Chapter 2. Numerical modeling ..................................................................... 09 2.1. Explanation of model............................................................................... 09 2.2. Governing equations................................................................................ 11 2.3. Calculation conditions.............................................................................. 18 2.4. Heat source............................................................................................. 20 Chapter 3. Results of computational analysis.................................................... 21 3.1. Condition 1: Height of lance from melt surface.......................................... 21 3.1.1 Results of computational analysis ............................................................. 21 3.1.2 Microstructural analysis of lance surface....................................................28 3.1.3 Results of process application................................................................... 37 3.1.4 Summary....................................................................................................46 3.2. Conditions2: Feeding system........................................................................47 3.2.1 Comparing feeding system ....................................................................... 47 3.2.2. Result of computational analysis: Melt velocity........................................... 50 3.2.3. Result of computational analysis: Penetration depth................................... 54 3.2.4. Result of computational analysis: Melt splash............................................ 58 3.2.5. Result of computational analysis: Reaction area......................................... 60 3.2.6. Result of computational analysis: Temperature of lances........................... 77 Chapter 4. Results of microstructure analysis...................................................... 80 4.1. unused and fractured lance......................................................................... 83 4.2. Used lance in various height........................................................................ 93 4.3. High magnification analysis........................................................................ 105 4.4. Thermodynamics calculations..................................................................... 108 4.5. Lab experiments.......................................................................................... 117 4.5.1 Conditions of lab experiments....................................................................117 4.5.2 Condition 1: 1000℃ .................................................................................. 119 4.5.3 Condition 2: 1100℃ .................................................................................. 121 4.5.4 Condition 3: 1090℃ ...................................................................................126 4.5.5 Summary....................................................................................................130 Chapter 5. Conclusions........................................................................................ 131 References...........................................................................................................133Docto

Axin2-GSK3β 복합체 결합부위의 분자 특성화

치의학과/박사[한글]암환자의 90% 이상이 상피 기원의 암종이며, 상피간엽이행 현상은 암의 초기 단계에서 침습성 암종으로의 진행 과정에 연관되어 있다. Wnt 신호전달은 Snail의 인산화를 억제시키는데, 이러한 과정은 Axin2에 의한 GSK3β의 핵외 수송을 통해 일어나며 이로 인해 E-cadherin 억제인자인 Snail 발현이 증가되고 상피간엽이행이 유도된다. 이 과정에서 LRP5/6를 통한 Axin의 활성화가 Wnt 신호 전달에 필수적인 것으로 알려져 있으나, LRP5/6를 통한 nuclear GSK3 comparmentalization에 대해서는 거의 알려져 있지 않다. 또한 최근에 알려진 Axin과 GSK3β의 결합구조에 따르면, Axin과 GSK3β 간에는 다수의 소수성 결합과 하나의 수소 결합이 있으며, Axin에서 나선형의 ‘ridge’를 이루는 소수성 아미노산 잔기 부위가 GSK3 β의 나선형 구조와 연결된 루프 구조 사이에 형성된 소수성의 ‘groove’ 부위로 접혀 들어가는 형태로 결합이 일어난다. 그러므로 LRP5/6를 경유하는 Wnt 신호 전달 및 EMT 유도과정에서 Axin과 GSK3의 결합 부위는 Snail 발현을 조절 할 수 있는 분자 표적으로서 가능성이 있으나 이에 대한 연구는 거의 없다. 따라서 본 연구는 LRP5/6에 의한 GSK3 nuclear compartmentalization 조절과 그 과정에서 Axin의 역할을 규명하고, 또한 Axin2-GSK3β 단백질 간 결합에 관여하는 주요 분자 결합부위를 파악하고 이를 타겟하는 화합물을 이용하여 Axin2-GSK3β complex의 치료 타겟으로서의 가능성을 알아보고자 하였다. 결과는 다음과 같다. 1. LRP6 보조 수용체는 Snail을 안정화시키고 핵 내 농도를 증가시키는데, 이는 Axin2에 의한 GSK3β의 nuclear export function에 의존한다. 2. GSK3β mutants를 이용한 in vitro binding assay 결과, GSK3β 의 Y216 and V267/268 부위가 Axin2와의 결합에 중요한 부위이다. 3. Axin2의 소수성 아미노산 잔기인, L374와 L378부위가 Axin2-GSK3β 단백간 상호작용에 중요한 부위이며, 수소결합 부위인R377부위는 Axin2-GSK3β 결합에 결정적이지 않았다. 4. Pharmacophore 모델을 통해 선택된 Axin2-GSK3β결합억제 선도물질은 핵 내 GSK3β 발현을 증가시키고, Snail은 억제시켰다. 또한 E-cahderin 발현을 증가시키고 암세포의 이동을 억제시켰다. 이상의 결과에서 GSK3β의 nucleocytoplasmic compartmentalization의 조절에 LRP5/6 보조수용체와 Axin2가 관여함을 알 수 있었고, Axin2-GSK3β 결합의 부위는 상피간엽이행을 억제하는 타겟으로 적절함을 알 수 있었다. [영문]About 90% of human cancers originate from epithelial tissue, and epithelial mesechymal transition (EMT) is related in the conversion of early stage tumors into invasive malignancies. Wnt signaling inhibits Snail phosphorylation through Axin2-dependent nuclear export of GSK3β, then consequently increases E-cadherin repressor, Snail protein levels and induces an EMT. The important roles of LRP5/6 on Axin activation had been described, but it’s roles of nuclear GSK3β compartmentalization had not been well-known. According to the structure of Axin-GSK3β complex reported recently, the Axin makes several hydrophobic interactions and only a single hydrogen bond to GSK3β. Hydrophobic amino acid residues of Axin form a helical ‘ridge’ that packs into a hydrophobic ‘groove’ formed between helix and the extended loop in GSK3β. The possibility of molecular target for Axin2-GSK3β binding sites had not been verified yet. Thus, this study was aimed to elucidate the regulatory cascade of GSK3β compartmentalization by Wnt co-receptor, LRP5/6 and clarify the roles of Axin2 during the process, and to verify potential therapeutic target for Axin2-GSK3β complex though validate the anti-EMT effect of chemical candidates blocking the principal Axin2-GSK3β protein-protein interaction sites. The results are as follows: 1. LRP6 stabilizes Snail and sustains its nuclear accumulation by Axin2-dependent nuclear export of GSK3β. 2. Amino acid residues of Y216 and V267/268 in GSK3β is crucial binding sites to interact with Axin2 according to in vitro binding assay with GSK3βmutants. 3. Hydrophobic amino acid residues of Axin2, L374 and L378 form principal Axin2-GSK3β protein-protein interaction, but a single hydrogen bonding residue R377 is not critical for Axin2-GSK3β binding. 4. The target molecule of Axin2-GSKβ interaction, selected by pharmacophore model, increases nuclear GSK3β expression and its activity, consequently decreases Snail expression. The target also increases E-cadherin expression, and inhibits cancer cell migration. The results of the study clarified the functional regulation of GSK3β nucleocytoplasmic compartmentalization mediated by LRP5/6 and Axin2, and verified the possibility of molecular target for Axin2-GSK3β binding sites as anti-EMT target.ope