The manufacturing of hot metal in a blast furnace is one of the important parts of an integrated steel plant. In a blast furnace, the quality and productivity of the output (hot metal) depends on a large number of input and operating variables. In this paper, we simulate complex interactions of technological and financial variables. We chose system dynamics principles to simulate the blast furnace for project evaluation as a useful aid to managerial decisions. The model would be used to answer a number of questions related to investment decisions. We simulate the actual production of hot metal, accumulated hot metal production, net works cost and cost of hot metal per ton for a period of 36 months with real data.