Hot Metal Pretreatment

Hot metal pretreatment is a process performed on hot metal after the tapping of a BF (blast furnace) and before decarburization in a BOF (basic oxygen furnace). In most cases, this process lowers the impurity content of the hot metal. Hot metal desulfurization, desiliconization, and dephosphorization are all processes that are included in this category.Among the various reactions that take place, desulfurization plays the most important role in hot metal pretreatment. This process was first used in the 1960s, and at present, desulfurization is the only hot metal pretreatment used in most steelmaking shops, except in some eastern Asian countries. The use of hot metal dephosphorization began in the 1980s in Japan. The advantage of this process originally was the cost reduction. Recently, when combined with the recycling of decarburization slag, it has also made reduced slag generation possible, which is another advantage. Hot metal desiliconization was developed to adjust the slag volume in order to minimize the cost of refining.In this chapter, we first explain the fundamentals of each type of reaction in terms of the thermodynamics and kinetics involved, and then we introduce an example of each process.