Modifying hot slag and converting it into value-added materials: A review

Waste heat of metallurgic slags at 1450-1650 °C are the largest secondary energy which are still not reused in iron and steel industry. How to reuse such huge slag and its waste heat have become a great challenge for constructing a greener iron and steel industry. A method for directly modifying hot slag and converting it into value-added materials has been developed in recent years. Two kind of hot slag modification technologies are firstly reviewed in this paper. Crude modification of hot slag was conducted to enhance its properties such as disintegration, volume expansion, cementitious reactivity, heavy metal leaching, iron component recovery, etc. Fine modification of hot slag has been developed to prepare high value-added products, such as glass-ceramics, mineral wool and fertilizers. Moreover, dispose of hazardous solid waste and recovery of valuable metals by hot slag modification method were introduced as two significant research trends from the economic and environment point of view. Finally, many bottleneck problems on application of hot slag modification technologies are proposed. Related researches in this areas will construct a green industrial chain among metallurgy, silicate and environmental industry in the future, and hot slag modification technologies as a core has a broader development perspective.