1. Institute for Industrial Furnaces and Heat Engineering, RWTH Aachen University; Kopernikusstraße 16 52074 Aachen Germany
2. Department of Metal Extraction and Recirculation; Technical University of Czestochowa; AK 19 42-200 Czestochowa Poland
3. Institute of Thermal Machinery, Technical University of Czestochowa; AK 21 42-200 Czestochowa Poland