Producing steel is an art

Doing it automatically is information technology

Today steel is produced mostly by the converter process, an expensive and energy- intensive method. Now the next generation of steering systems is being brought forth in a research project with metallurgists and control engineers working together. This is how tomorrow’s steel production will be less energy consuming, more environmentally friendly, and safer.

The converter process has been in use for more than 50 years and today it is the overwhelmingly dominant method for producing steel. The purpose of the process is to reduce the amount of carbon and silicon and other impurities in the raw iron coming from the blast furnace. This is done by blowing pure oxygen against the molten metal’s surface and oxidizing the impurities. The cost of running the converter process is high, primarily because it is slow and uses huge quantities of pure oxygen.

The goal of converter process control is to achive the proper chemical composition of the steel and a given temperature for the molten metal. Since neither the temperature nor the content of carbon or silicon can be measured in real time, the process is steered manually. A skilled and experienced blower knows how to make use of the measurable and perceptible quantities to estimate what the consequences of steering measures would be.
Blowing oxygen at supersonic speed on molten steel at 1,700O C is no joke, and many things can go wrong. Therefore, an automatic system for steering the converter process is high on the wish list of the steel industry.

At the Department of Information Technology control engineers are collaborating with metallurgists from the Royal Institute of Technology in Stockholm in a research project that aims to produce a new reliable and efficient system. To develop such a system, first all chemical and physical phenomena that occur in converter blowing need to be described by equations. Mathematical modeling not only provides insights into how the process works but also into how the process can be improved and where the limits of the technology lie. This is where close cooperation is needed between metallurgists, control engineers, physicists, and mathematicians.

Alexander Medvedev