ArcelorMittal Bremen GmbH, Bremen, Germany:

Sauerwald J., Dr.-Ing.
Franzen A., Dr.-Ing., e-mail: andreas.franzen@arcelormittal.com
Fischer A.
Buhles T., Dr.-Ing.
Janz J., Dr.-Ing.

Muon tomography for analyzing the density distribution in blast furnaces is introduced as a new measurement tool. The application at blast furnaces requires a special muon detector system. The characteristics of the system are determined by calibration measurements at a slab stack. At blast furnace No. 2 of ArcelorMittal Bremen three different types of scans are performed in the area of the coke network and the cohesive zone. The density distributions display areas of different density within the coke network which can give information about the situation inside the blast furnace, especially the position and the shape of the cohesive zone. This knowledge can be used to stabilize the cohesive zone and, thus, the whole process. In a new approach the coke network and the cohesive zone are investigated during reduction process by muon tomography. For the harsh conditions at blast furnaces a special detector system was developed. Reference measurements at a slab stack with different path lengths through iron are pre-sented. The attenuation can be approximated by an exponential law in the area of interest. The counting rates between 1000 and 5000 muons per hour at the slab stack are in the same order of magnitude as the ones at the blast furnace. Therefore, the results are suitable for the calibration of the detector system. Three different types of scans are performed at the blast furnace No. 2 of ArcelorMittal Bremen. Assuming a radial symmetry in first approximation the results show that in a lower area of the coke network two different densities can be found. In an inner cylindrical area with a radius of 3.5 m the density is determined to 2.5 t/m³ and in the remaining outer area 1.6 t/m³. The presented results show that measurements of the density distribution in the lower part of a blast furnace are possible and can help to monitor the position and shape of the cohesive zone for a stabilization of the blast furnace process.

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