Heat recovery process modelling of semi-molten blast furnace slag in a moving bed using XDEM

As a valuable byproduct of the iron-making process, blast furnace slag with temperature up to 1450–1650°C contains a tremendous amount of sensible heat. Dry granulation and waste heat recovery via a moving bed is an attractive alternative to the conventional water quenching method due to energy-savings and the reduction in water consumption. In this study, the extended discrete element method (XDEM) as a numerical simulation method is adopted to investigate the heat transfer characteristics of semi-molten slag particles in a moving bed. The solidification and cooling processes inside the particles are described using one-dimensional (1D) and transient energy conservation equations and the enthalpy method is used to describe the release of latent heat. The result is compared with a case in which the temperature inside the particles is considered to be uniform. The numerical results indicate that the convective and radiative heat transfer rate and the released sensible and latent heat are all higher when the initial semi-molten state of particles is considered, but the waste heat recovery rate of a particle won't make much difference. The results of this research provide a theoretical basis for the accurate industrial simulation of the heat transfer in a moving bed.