Reduction of Odor Emissions from Pyrometallurgical Metals Recovery from Secondary Raw Materials

K. Jaworek, J. Mrozowski, M. Bąk

Many industrial processes, including the production of non-ferrous metals from primary and secondary raw materials, generate odors in the off-gases. Odors emitted into the atmosphere cause nuisance to the habitants in the direct vicinity of the emitters. Organic and inorganic compounds sensed by the olfactory receptors at very low concentrations, are responsible to a large extend for odor nuisance. To the malodorous compounds occurring in industrial gases almost all groups of the chemical compounds like: aliphatic and aromatic compounds, aldehydes, ketones, carboxylic acids, thiols, amines, sulfides, disulfides, thiophene derivatives and nitriles are included. The paper presents the research results of possibility to reduce odor nuisance of off-gases. In order to odor neutralization the gases were subjected to oxidation processes using H2O2, O3 and ClO2. The chromatographic analyses were performed in terms of gas composition and the content of organic substances, in particular generating nuisance odor. In exhaust gases were detected 320 organic compounds, including aldehydes, thiophenes, carboxylic acids and compounds with nitrogen and sulfur. Then, gases were oxidized through their contact in a scrubber or a sprayed column with oxidizing solutions. Studies were carried out in different conditions of pH and oxidant dosages. The efficiency of gas deodorization was determined by analyzing the chemical composition of off-gas after oxidation processes. In addition, evaluation of the degree of deodorization was conducted assuming the contractual organoleptic odor intensity scale ranging from 1 to 5 indicating the intensity of the gas aroma. The study showed that ozone and chlorine dioxide are the most effective to limit odor nuisance of gases from pyrometallurgical processes, which are based on secondary raw materials.