鋼鐵工業是以生產各種鋼鐵產品為主的行業，為國家建設的基本工業，被稱為工業之母。全世界任何一個國家，鋼鐵工業常被視為國力強弱的象徵。為了可以使國內的鋼鐵業產能能夠得到提升，本文將於鋼鐵業中的製鐵製程進行深入探討。本研究利用計算流體力學模擬三相流體經由噴流的方式注入高爐主流道的流動行為及鐵渣分離性。其中，物理模型是根據中鋼四號高爐主流道；且分別利用 方程式和體積分率法描述於主流道衝擊區紊流流動及空氣、鐵水與爐渣三相流體；而壓力場和速度分佈則藉由有限體積法和隱含式壓力流速藕合運算法求得，並運用牛頓黏度定律來獲得壁面剪切應力分佈，並與中鋼四號高爐主流道受侵蝕之鐵水線作比對，以驗證本實驗之數值架構的合理性。最後再以主流道進出口之質量流率來計算其鐵渣分離性。從結果顯示，雖然由熱浮力現象所造成的漩渦流動對主流道耐火材會造成若干程度的侵蝕，但其遠小於衝擊區因紊流所造成的侵蝕，故如何降低衝擊區主流道耐火材受侵蝕的程度，才是延長主流道壽命主因。本文發現，當主流道內的流體流速越快，則分離效果不彰；當渣道口與鐵水出口之高度差大於0.2公尺時，則可獲得較佳之鐵渣分離性；擋板高度越低，則擋板前之主流道系統液位會較易升高，導致鐵水較易流往渣道而造成浪費；此外，對於不同寬度主流道之比較可發現，寬度最窄的主流道會於渣道附近產生紊流，此強制對流則會把若干鐵水捲進渣道；而不同出鐵口仰角會影響主流道衝擊區的位置，對鐵渣之分離性也會造成若干影響。 Iron and steel industry turn on making every steely product and it is the basic of country reconstruction. It is called the mother of industry. For any countries, it would be considered to view as strong or weak of nation power. In order to increase production capacity on iron and steel industry in our country, the article will concentrate deeply on making iron processing. This paper aims to simulate three phases fluid flow and separation of iron and slag in main trough of the blast furnace during tapping process by means of computational fluid dynamics (CFD) technology. The physical model is based on main trough of the blast furnace no. 4 at China Steel Co. (CSC BF4). The k-εequations and volume of fluid (VOF) were used for describing turbulent flow at the impinging zone of trough and indicating liquid iron and air in the governing equation respectively. The pressure field and velocity profile were then obtained through finite volume method (FVM) and pressure implicit with splitting of operators (PISO), followed by calculating the wall shear stress through the Newton’s law of viscosity to analyze the wall shear stress profile of simulation, and comparing with the wear profile of CSC BF4 main trough to test the numerical solution. Finally, we use the mass flow rate to calculate the separation efficiency in this study. As shown in the numerical results, the thermal buoyancy results in the erosion of the main trough but its effect is lower than turbulent flow in the impinging zone. It was found that the fluid velocity in the main trough is faster, then the separation efficiency is worse; and if the height difference between iron dam and slag port is higher than about 0.2m, the separation efficiency will be an optimum. In addition, the results indicate that the height of skimmer is higher, the separation is better; if the width of the main trough is narrow, the flow field nearby slag port will produce turbulence. It can carry some iron into slag port; the angle of taphole can affect the position of impinging zone, so it can also influence result of separation efficiency.