DETERMINATION OF THE CARCINOGENIC PAH YIELDS IN ALUMINUM INDUSTRY USING SODERBERG ELECTROLYZER

摘要

Slow heating (l℃/min) and rapid heating (70℃/min) carbonization of medium-softening-point pitch (MP), high-softening-point pitch (HP) and anode pastes based on them have been studied. It was determined that replacing MP with HP the tar yield decreases 1.5 times, at that the yields of carcinogenic polycyclic aromatic hydrocarbons (PAH) benzo(a)pyrene (BaP), benzo(a)anthracene (BaA), dibenzo(a,h)anthracene (DBA) do not change. So the tar yield during the carbonization of the coke-pitch compositions can not serve as a criterion of carcinogenic danger. It was shown that during the rapid heating carbonization of the anode pastes the yield of tar and carcinogenic PAH increases about 10 times in comparison with that of the slow heating carbonization. Based on this the most significant source of carcinogenic danger of vertical stud Soderberg technology (VSS) was determined - the open hole during stud repositioning, and its contribution in atmospheric emissions is equal to 60-70%. The specific yields of tar and BaP from the main sources of PAH of VSS technology using the anode pastes based on MP and HP were determined. It was shown that the use of the anode pastes based on HP leads to a significant reduction of the specific yield of tar from all the sources. However, the specific yield of BaP does not change. So the replacement of MP with HP does not reduce carcinogenic danger of this production.