Author(s):
1. Dragutin Nedeljkovic, Institute of Chemistry, Technology and Metallurgy, National Institute, University of Belgrade, Serbia
2. Lana Putic, Institute of Chemistry, Technology and Metallurgy, National Institute, University of Belgrade, Serbia
3. Slavisa Putic, University of Belgrade, Faculty of Technology and Metallurgy, , Serbia
4. Aleksandar Grujić , Serbia
5. Jasna Stajic-Trosic, Institute of Chemistry, Technology and Metallurgy, National Institute, University of Belgrade, Serbia

Final paper