Effects of inorganic chloride on the partitioning and speciation of heavy metals in a laboratory incinerator

The effects of inorganic chloride on the partitioning and speciation of heavy metals during waste incineration, considering different chloride contents, combustion temperatures, and metal concentrations in the wastes were examined using a tube furnace. The results indicated that heavy metal partitioning was fundamentally affected by the sodium chloride content, combustion temperature, and the volatility of the heavy metals and their compounds. The volatility was enhanced by increasing the combustion temperature and sodium chloride content in the waste. A higher combustion temperature and sodium chloride content in the waste tended to partition the metals into the fly ash or flue gases by forming volatile metal chlorides. The analysis of heavy metal species analysis for the incinerator ashes showed that most metal compounds were formed as oxides. Crystalline phase identification identified, the compounds, PbO, NaCl and KCl, in the fly ash, and ZnO, Zn(OH)₂, NaCl, KCl, Pb₂O₃, as well as elemental copper, lead, and zinc in the bottom ash. The formation of NaCl and KCl in both the fly and bottom ash may be explained by the stronger affinity of Na and K to the spiked chloride.