Laboratory for the iron ores of the future

Thyssenkrupp Steel is investing 2.4 million euros in the expansion of the existing blast furnace laboratory in Duisburg-Schwelgern. The investment supports efficient process control and raw material evaluation for the direct reduction plant.

As part of its transformation toward climate-neutral steel production, Thyssenkrupp Steel is investing in a new testing laboratory at its Duisburg-Schwelgern site. The facility expands the capabilities of the metallurgical laboratory and enables ISO‑compliant testing of feedstocks for the future direct reduction (DR) plant. The contract was awarded to Heat and Power Engineering GmbH, which has already designed and built a pilot plant for sinter production for Thyssenkrupp Steel. The contract has a value of 2.4 million euros.
The metallurgical laboratory in Schwelgern already has extensive testing capacity for traditional blast furnace feedstocks such as sinter, iron ore pellets, lump ore, and blast furnace coke. Approximately 2,000 tests per year form the basis for quality assurance of the blast furnace route. To meet the new requirements of hydrogen-based direct reduction, the existing laboratory is now being expanded.

New ISO tests for hydrogen-based production conditions

The process conditions in a direct reduction plant differ significantly from those in a blast furnace process. While blast furnaces are characterized by CO-rich process gases and temperatures well above 1,000 degrees Celsius, the direct reduction process operates with hydrogen-rich gases at temperatures of around 1,000 degrees Celsius or lower. The pellets and lump ore used must therefore be tested in accordance with ISO standards for direct reduction processes. The focus is on their stability under direct reduction conditions. Among other things, tests examine whether they tend stick or agglomerate during reduction, how strongly they tend to break down during reduction, and how well they can be reduced . The latter is a decisive factor for the plant productivity, as it directly influences the reaction rate in the reduction process.
The test atmosphere of the new test facilities is modeled after future operating conditions: While blast furnaces currently contain only about two percent hydrogen in the process gas, the direct reduction route is already being tested with around 45 percent hydrogen during natural gas operation – a value corresponding to the natural hydrogen content in natural gas. With the planned hydrogen ramp-up, the test conditions will be gradually adjusted to increasing hydrogen contents so that realistic and process-relevant results can be achieved at all times. Two test furnaces also allow steam injection to study its influence on feedstockspecific reduction rates. These investigations are intended to complement the ISO tests in the future, thereby enabling a more comprehensive evaluation of feedstocks and process conditions.

Raw material evaluation tailored to the combination of a direct reduction plant and a remelting furnace

A distinctive and innovative feature of the future process route is the combination of a direct reduction plant and electric smelters. Since impurities can be removed from the hot metal in the smelter through specialized slag metallurgy, the range of suitable feedstocks expands significantly: in addition to specialized DR pellets, conventional blast furnace pellets can also be used. This enables a significantly more flexible raw material strategy. At the same time, the importance of precise laboratory quality assurance is increasing, as blast furnace pellets have not yet been systematically tested for their suitability for use in the DR plant. In the future, Thyssenkrupp Steel will assess DR suitability itself – with the new DR laboratory serving as the central technical foundation.
Source: Thyssenkrupp Steel