Three-Stage Method Energy–Mass Coupling High-Efficiency Utilization Process of High-Temperature Molten Steel Slag

Abstract

High-temperature molten steel slag is a large amount of industrial solid waste containing available heat energy and resources. This paper introduces an efficient and comprehensive utilization process of high-temperature molten steel slag. The waste heat energy in the high-temperature molten steel slag can be fully recovered through the three-stage heat exchange. Through mass balance and energy balance, the theoretical heat recovery rate can reach 81.42 pct when the waste heat stored in steel slag is converted into usable heat energy, and the exergy efficiency of the overall system is 27.93 pct. When the waste heat stored in the steel slag is converted for electric energy, the theoretical heat recovery rate can reach 24.49 pct, and the exergy efficiency of the overall system is 33.83 pct. When the waste heat stored in steel slag is used for cogeneration, the theoretical heat recovery rate can reach 83.98 pct, and the exergy efficiency of the overall system is 38 pct. The normal-temperature solid steel slag produced by the process is easy for iron selection and subsequent high value-added utilization. The solidification of steel slag in this process consumes a large amount of CO2 so that the free calcium oxide (f-CaO) in the steel slag is fixed, which is more conducive to subsequent utilization, thereby achieving the purpose of energy saving and emission reduction. Compared with the utilization of traditional steel slag, this process can better utilize the energy and resources contained in steel slag and provides a new method for fully utilizing the waste heat energy and resource attributes of high-temperature molten steel slag.