M. Peters’s research while affiliated with ThyssenKrupp AG and other places

Numerous plant and process developments have led to the reduced consumption of raw materials and energy, increased yields and improved environmental protection in iron- and steel-producing plants. However, the extreme rise in demand for raw materials and changes in the deposits have created new challenges for plant operators regarding the flexibility and quality of raw materials. Both processes are followed by further process steps in order to manufacture the desired steel grades. Two- thirds of the steel produced in Germany is made via the blast furnace/converter route, and the remaining one-third is made via EAFs. Both routes for steel production are energy-intensive. Steel scrap is used in 42% of Germany's steel production. This demonstrates the sustainability of steel production shown, in particular, by the closed circulatory system of scrap steel recycling.

The growing production of hot metal - in due relation to the demand - forms the basis of the world's increasing demand for steel. In this context the blast furnace process will remain the number one ore reduction process. In Germany hot metal and crude steel are produced on a competitive basis at several integrated steel works using blast furnaces and basic oxygen converters which are world leading in terms of plant technology and operation. Within the framework of research programs, the development of an oxygen blast furnace process is underway, which - in combination with a CO2 capture and storage (CCS) system - is expected to massively reduce CO2 emissions from hot metal making. Direct reduction processes produce solid direct reduced iron (DRI) from iron ore without the use of coke. DRI is mostly used as input material in electric steelmaking. The majority of the DRI is produced in gas-based processes, especially at locations where low-cost natural gas is available. The intention of coal-based smelting reduction processes is to produce liquid hot metal without or only with very small amounts of coke. Of the various technologies, the Corex and the Finex processes have so far been applied to industrial-scale production. Whereas the Corex process relies on the use of lumpy ore charge, Finex can be operated with fine ores. Both processes will require the CCS technology to achieve a substantial reduction in CO 2 emissions.

The evolution and some highlights of iron making in Western Europe are reported, including ideas for CO2 lean steelmaking: Introduction into the development of hot metal production in Europe, progress of the structure of reductants and ore burden materials, sintering of iron ores, evaluation of constructional features and equipment of the blast furnaces and further outlook for the European ironmaking scenario. The integrated steel works in Western Europe operate modern plants for the production of a wide variety of high grade steel products. The blast furnace/converter route will remain dominant. One main focus is set on the future CO2 trading system based on benchmarks with non reachable values as set by the European Commission.

The steel industry in Europe and South America was hit hard by the world economic crisis with hot metal and crude steel production dropping vertically in few months only. several blast furnaces are temporarily stopped or running with low productivity though there are some signs of recovery and very important lessons were learned.

Thyssen Krupp Steel (TKS), Duisburg, Germany has developed and implemented a new electromotive forces (EMF) measurement-based method for continuous assessment of liquid iron filling levels and dead man position inside its Schwelgern blast furnace (BF) No. 2. The EMF measurements are performed by measuring the potential differences between multiple measuring positions at the blast furnace cell and a reference point. Four EMF sensors are installed at the circumference close to the blast furnace tapholes (TH) and four such sensors are installed above the TH, at the tuyere level (TU), while one sensor is installed as reference point (RP) at ground level, to perform EMF measurements. Each of these EMF sensors consists of a mounting link, welded to the blast furnace shell, an isolated cable, and a Pt100 thermocouple, for monitoring the sensor temperature, while all individual EMF signals are balanced to each other, to avoid irregular partially strong disturbances and and unknown signal drift.

To maximize furnace campaigns and to minimize production downtimes through short lining times, the entire integral blast furnace area, including the auxiliary units, has to be theoretically partitioned. The evolution of measures for extending furnace life is in conjunction with the investigation and understanding of the in some respects very complicated wear mechanisms and their causes. Of most importance are the constructional, material and process engineering measures to reduce wear and the measuring instrumentation for early detection and progress monitoring of wear.

ThyssenKrupp Stahl operates four blast furnaces with a hot metal production of up to 12 million tons per year in total. To minimize the costs in the cast house operation and to optimize the tapping performance, measures were taken to prolong the lifetime of the refractory lining of the troughs by a supreme effort. Extensive technical measures in the total cast house area with the aim of best economical efficiency were taken. This report shows the effects for the cast houses of the big Schwelgern furnaces.

Blast furnace hearth life is of major importance for economic efficiency and safety of the blast furnace process. Strong wear leads to a shortening of blast furnace campaign life and increases the risk of a possible blast furnace breakout. Hence, the blast furnace operator has to define a capable tapping strategy to reduce the wear of the hearth lining. This requires the knowledge of the actual blast furnace hearth conditions as well as the actual amount of tapped hot metal. Recently applied methods for determination of hot metal mass flow rates are located further downstream the process line which, in turn, do not enable an on-line measurement. Two new approaches for continuous determination of hot metal mass flow rates were tested by Betriebsforschungsinstitut VDEh-Institut for angewandte Forschung GmbH in laboratory trials at a physical model of the iron runner system as well as in operational trials at blast furnace 2 of ThyssenKrupp Stahl AG in Schwelgern. Thereby, the approach of hot metal mass flow rate determination by measuring the filling level within the iron runner has been proved suitable for operational practice. Herein, the wear of the iron runner is taken into account by a statistical wear model. Based on these investigations, a suitable method for continuous on-line measurement of hot metal mass flow rates has been made available for the first time at one iron runner of a multiple taphole blast furnace.

Owing to the concentration of hot-metal production on a few large-capacity blast furnaces only, it is imperative to fully use all technical opportunities for extending the blast furnace campaigns. The design and the layout of blast furnaces together with the blast furnace operation are the most important criteria for the campaign life. The admittedly high level of the state of the art, at the same time be regarded as a challenge for the future to expand the available know-how to ensure minimization of the abrasive, thermal and chemical wear and as such to massively extend the service life of all units of an integrated furnace plant.