A New Lance Design for BOF Steelmaking

Abstract

This article summarizes the outcome of research work carried out to improve the performance of the oxygen lance in the LD steelmaking process. It is stated that the lack of control of the foamy slag and the augmentation of interfacial area creation between the slag and metal are the major hindrances in running the process effectively for improved turn-down steel quality. The ineffectiveness of the existing design in producing liquid metal droplets in the presence of slag foam is explained. In order to augment the droplet generation, a new oxygen lance with a central subsonic nozzle through which flow can be controlled has been introduced and its blowing performances studied using numerical and water model studies. The jet characteristics studied in the numerical simulations show no jet coalescence. The interferences of the jets with the bath have further been analyzed by hydrodynamic model studies. It has been found that the droplet generation rate improves significantly due to the presence of the central jet. Further, it has been observed that controlling the flow rate through the central hole can be used as an effective process control tool.