Molten blast furnace (BF) slag is discharged at high temperature during the iron-making process, and contains a high content of thermal energy. Traditional water quenching methods fail to recover this thermal energy. Hence, a number of dry granulation heat recovery techniques were proposed, and reducing the particle size is regarded as the key route to improving heat recovery efficiency. Among all the proposed techniques, the centrifugal granulation method is recognized as the most promising. In this paper, the centrifugal granulation characteristics for molten BF slag in film formation mode were experimentally studied. The effect of the rotating speed, the molten slag mass flow rate and the slag initial temperature on the particle size are discussed. The results show that an unusual histioid type of film disintegration phenomenon occurs during the granulation process, which is beneficial to the fragmentation of the film. Furthermore, a higher rotating speed and a smaller slag flow rate contribute to the reduction of particle size. The present study provides guidance for improving granulation heat recovery performance for molten BF slags in industrial applications.
Keywords Molten slag; Thermal energy recovery; Centrifugal granulation; Film formation mode