Primetals upgrades Salzgitter's BOF system

According to the plant supplier, the new Slag Expert model has optimized the use of lime, improved the hitting rate – i.e. the amount of successful heats in terms of carbon content and steel temperature – and reduced the number of reblows.

Slag Expert is a new module for Primetals Technologies' process optimization system (Level 2) that calculates the target value for the required basicity of the slag at the end of the blowing process. Additionally, it provides the basis for determining the optimum amount of lime.

The process optimization system from Primetals Technologies has already been in use at Salzgitter Flachstahl’s three 220-ton LD converters (BOFs) for 15 years.

Christian Schlüter, head of melting operations, commented: "We were able to meet the identified improvements after just a few weeks, and we even exceeded them in some cases. The most important aspect for us is to optimize the input of lime in order to meet the required phosphorus levels.”

Slag Expert calculates the desired slag basicity at the end of the blowing process based on the amount of silicon in the feedstock, a pig iron analysis, and the targeted parameters of temperature, carbon, and phosphorus content in the crude steel composition. The availability of stirring plugs and the age of the converter are also taken into account. The module then calculates the values for lime saturation, phosphorus capacity, and viscosity of the slag.

The Slag Expert module is a result of many years of close collaboration between Salzgitter Flachstahl and Primetals Technologies, stated the latter. For over 10 years, the process optimization systems have been maintained and improved as part of a services contract. In addition to the Level 2 systems at the LD converters (BOFs), this co-operation also focuses on automating the complete secondary metallurgical process as well as topics related to intralogistics and, for example, scrap management.