Heavy metal vaporization and abatement during thermal treatment of modified wastes

Abstract

This study examines the vaporization percentage and partitioning of heavy metals Cd, Pb and Zn during thermal treatment of wastes with added PVC, heavy metals or phosphate, and the efficiency of sorbents for removal of these metallic compounds in flue gas of an industrial solid waste incinerator. Firstly, vaporization experiments were carried out to determine the behavior of heavy metals during combustion under various conditions (type of waste, temperature, presence of chloride or phosphate ...). The experimental results show relatively high vaporization percentage of metallic compounds within fly ash and limestone matrix while heavy metals within sediments treated with phosphoric acid are less volatile. Vaporization of metals increases with increasing temperature and with chloride addition. The thermal behavior of the selected heavy metals and their removal by sorbents (sodium bicarbonate, activated carbon) was also studied in an industrial solid waste incinerator. These pilot scale experiments confirm that heavy metals are concentrated in fly ashes and cyclone residues, thus effectively controlling their release to the atmosphere.

Fixation and partitioning of heavy metals in slag after incineration of sewage sludge

“…For Pb and Mn, the lowest fixation rates were obtained with a residence time of 20 min, The fixation rate of Pb tended to be stable at residence time of 25 min. Rio founded the vaporization equilibrium of Pb was reached at residence time of 120 min with 600°C furnace, furthermore, the equilibrium was obtained at residence time of 50 min with 850°C furnace (Rio et al, 2007). The largest fixation rate for Mn (65%) was obtained with a residence time of 60 min.…”

Experimental and thermodynamic investigation on transfer of cadmium influenced by sulfur and chlorine during municipal solid waste (MSW) incineration

“…Partitioning of heavy metals among the various incinerator residues depends on the MSW composition, the physicochemical properties of the metals and their compounds, and the incinerator operating conditions [10][11][12][13]. To understand the transfer of heavy metals during MSW incineration, it is necessary to study the influence of combustion conditions, such as temperature, gas composition, residence time and the presence of reactive compounds (chlorine, sulfur, or aluminosilicates), on the final metal speciation in the residues [1].…”

Characteristics of Melting Incinerator Ashes Using a Direct Current Plasma Torch

“…As for S1 and S3, the amounts of several heavy metals were even higher than those in raw ashes, such as Pb, Zn and Cu. The reason was that the high content of Chlorine in FA1 and FA3 impeded the stabilization of heavy metals [25][26][27] and the high value of basicity of FA1 and FA3 led to poor efficiency of vitrification [28]. It should be noted here, the total elemental mass balances were not considered in this study for some volatile metals such as Cd and Pb may evaporate to the atmosphere during molten stage.…”