Steel scrap is of great benefit for environmental protection. In converter steelmaking, bottom carbon injection was applied to enhance the scrap ratio and in EAF steelmaking, submerged carbon powder injection was used to accelerate the smelting of scrap. In these two cases, carbon powder is directly injected into molten metal to improve the scrap melting with effective carburization capacity and intense stirring effect. In this study, the induction furnace experiments were carried out to study the melting characteristics of steel scrap with different carbon contents and bottom-blowing gas flow rates. The results show that larger carbon content and faster fluid flow can promote scrap melting because the carburizing reaction can be accelerated by larger carbon concentration gradient and the heat transfer can be enhanced by larger stirring intensity. Finally, the convective mass transfer coefficient and heat transfer coefficient between steel bar and molten metal were also calculated.

In vanadium extraction converter steelmaking, the swirl-type oxygen lance has been applied to improve the dynamic condition of the molten bath reaction to achieve a higher oxidation rate of vanadium and better vanadium slag quality, because the swirl-type jet can generate not only axial and radial forces but also tangential ones. Recently, the swirl-type supersonic jet with preheated oxygen was proposed to further enhance the agitation ability of the oxygen jet on the molten bath. In this study, the effects of the ambient temperature and oxygen temperature on the swirl-type supersonic jet behavior were analyzed to achieve better formulation and optimization of the process parameters. The flow characteristics of swirl-type oxygen jets were simulated by computational fluid dynamics software at 300 K, and 1700 K ambient and 300 K, 450 K and 600 K oxygen temperature, and partial results were validated against data from a preheating jet experiment. An analysis of the results shows that the centerline jet velocity was increased by preheated oxygen, and at higher ambient temperature, a longer core length was formed and the velocity fluctuation was aggravated. The influence of the preheating temperature on the core length was more evident at lower ambient temperature. From a dynamic perspective, the molecular motion was improved and with respect to energy, the internal energy of the oxygen jets could be preserved at higher ambient temperature.

During the converter steelmaking process, gas-slag-metal three-phase emulsification is realized by injecting gas to complete metallurgical tasks such as slagging, dephosphorization, decarburization, and heating. As green and intelligent development of the steel industry progresses, converter steelmaking injection technology is also constantly innovating. In this review, the types and applications of top blowing injection elements, bottom blowing injection elements, and injection the medium are reviewed. Three different types of combined blowing processes are compared. At the same time, the advantages and disadvantages of different bottom blowing elements and injection media are respectively discussed. Finally, based on the research and application status of converter injection technology, the development direction of converter steelmaking injection technology is discussed. Accelerating the innovation of converter steelmaking injection technology, especially the improvement and breakthrough of high efficiency, reductions the environmental burden, and long life technology, will play an important role in promoting the transformation and improvement of the steel industry.