The productivity of the blast furnace Ironmaking process is significantly dependent on the slag chemistry. The presence of compounds like Al2O3 in high quantities can make the hearth slag highly viscous and difficult to tap. The objective of part-1 of this study is to provide a comprehensive analysis of the role of high alumina (Al2O3 > 15%) compositions in the blast furnace slags. Slag viscosity, liquidus temperature, activation energy, etc., are critically reviewed with respective solutions to operate under the desired conditions. Flow parameters of the slag are examined to understand the melting-softening phenomena which directly affect the slag tap-to-tap time. The addition of certain additives to the slag system has also been studied with the aim to improve the target properties of the slag. A range of slag compositions and their optimization techniques are discussed in this part to provide greater insight into the topic.