Green LD (BOF) Steelmaking—Reduced CO2 Emissions via Increased Scrap Rate

Abstract

The basic oxygen furnace (BOF) is the dominating primary steelmaking process. It is an autothermal process where hot metal and scrap are used as charging materials. The decarbonization and transformation of integrated BOF steelmaking will be the most important challenge in the coming years. Steel scrap is a charge material without new CO2 emissions, whose availability is expected to grow significantly and will play a key role in this decarbonization process. Several solutions have been developed by Primetals Technologies to provide additional energy for processing higher scrap rates in integrated BOF steelmaking. Such solutions include simple upgrade packages installed on existing converters such as process models for heat optimization, post-combustion, and scrap preheating lances. For higher scrap rates from 30% to 50%, a combination blowing converter and JET converter is required to provide sufficient mixing during scrap melting and the highest heat transfer from the increased post-combustion. Hybrid EAF–BOF operation and limitations regarding scrap quality also need to be considered for the transformation of steelmaking. Scrap sorting and processing can be a solution to reduce residual levels in crude steel for high scrap rates. Based on reference plant data, the CO2 reduction potential of the presented solution versus the effort and complexity of implementation is compared.

Influence of Oxy-Fuel Lance Parameters on the Scrap Pre-Heating Temperature in the Hot Metal Ladle

“…In the 1960s, foreign steel companies added heat-increasing agents to make up for the heat in the converter smelting process; common heat-increasing agents such as calcium carbide [8], silicon carbide, etc. Several researchers have found that enhancing the exothermic process of carbon and oxygen reactions in the converter can also increase the scrap ratio [9]. For example, Japan's Sumitomo Metals [10] industrial trial study found that the heat absorption rate of secondary combustion in the 15 t converter was close to 100% and the scrap ratio could be increased by 9%; the heat absorption rate in the 160 t converter reached up to 70% and the scrap ratio increased by only 6%.…”