Situation and prospect on investigation of ferroalloy reduction during steelmaking

As China steel industry continues to face more prominent overcapacity and environmental pollution problems, reduction of ferroalloy continues to attract more attention as a cost reduction and efficiency improvement method. In this paper, the current research status of ferroalloy reduction was summarized. Advancements on ferroalloy reduction were discussed from three aspects:ferroalloy physical and chemical characteristics, ferroalloy addition technique, and steelmaking process. The control technique of ferroalloy self-powdering, loss encountered under vacuum conditions during ferroalloy utilization, melting of ferroalloy in molten steel, and alternative techniques were introduced. These techniques can serve as a reference for ferroalloy reduction during steelmaking. The shape, physical, and chemical properties as well as complex structure affect the yield of ferroalloy during steelmaking. The manner of ferroalloy addition, sequence and time of ferroalloy addition were summarized and contrasted. Self-powdering and bitterness-powdering of ferroalloys are difficult problems during the utilization of these alloys, and should be controlled at the initial usage of ferroalloys. Powdered and volatile ferroalloys easily encounter loses under vacuum conditions, and better utilization can be realized by lowering the vacuum conditions, as it can lead to a low flow speed of the argon in the vacuum chamber and reduce the volatility rate of the elements in volatile ferroalloys. In addition, ferroalloys with different densities and granularities have different melting time and movement tracks. Large ferroalloys with a low density have a long melting time and easily float between molten steel and slag, which can cause ferroalloy oxidation. Therefore, the yields obtained using ferroalloys with different densities and granularities are different. Ferroalloys of different structures and granularities should be designed to optimize yields. The application of ferroalloy reduction techniques has extensive prospect. Investigation of the mechanism of ferroalloy loss, structural design of ferroalloys, as well as alternative techniques and control techniques should be key research areas in ferroalloy reduction during steelmaking.