Effects of sulfur on lead partitioning during sludge incineration based on experiments and thermodynamic calculations
- School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China)
- Guangdong Testing Institute of Product Quality Supervision, Guangzhou 510330 (China)
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China)
Highlights: • A thermodynamic equilibrium calculation was carried out. • Effects of three types of sulfurs on Pb distribution were investigated. • The mechanism for three types of sulfurs acting on Pb partitioning were proposed. • Lead partitioning and species in bottom ash and fly ash were identified. - Abstract: Experiments in a tubular furnace reactor and thermodynamic equilibrium calculations were conducted to investigate the impact of sulfur compounds on the migration of lead (Pb) during sludge incineration. Representative samples of typical sludge with and without the addition of sulfur compounds were combusted at 850 °C, and the partitioning of Pb in the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that three types of sulfur compounds (S, Na{sub 2}S and Na{sub 2}SO{sub 4}) added to the sludge could facilitate the volatilization of Pb in the gas phase (fly ash and flue gas) into metal sulfates displacing its sulfides and some of its oxides. The effect of promoting Pb volatilization by adding Na{sub 2}SO{sub 4} and Na{sub 2}S was superior to that of the addition of S. In bottom ash, different metallic sulfides were found in the forms of lead sulfide, aluminosilicate minerals, and polymetallic-sulfides, which were minimally volatilized. The chemical equilibrium calculations indicated that sulfur stabilizes Pb in the form of PbSO{sub 4}(s) at low temperatures (<1000 K). The equilibrium calculation prediction also suggested that SiO{sub 2}, CaO, TiO{sub 2}, and Al{sub 2}O{sub 3} containing materials function as condensed phase solids in the temperature range of 800–1100 K as sorbents to stabilize Pb. However, in the presence of sulfur or chlorine or the co-existence of sulfur and chlorine, these sorbents were inactive. The effect of sulfur on Pb partitioning in the sludge incineration process mainly depended on the gas phase reaction, the surface reaction, the volatilization of products, and the concentration of Si, Ca and Al-containing compounds in the sludge. These findings provide useful information for understanding the partitioning behavior of Pb, facilitating the development of strategies to control the volatilization of Pb during sludge incineration.
- OSTI ID:
- 22470226
- Journal Information:
- Waste Management, Vol. 38; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM OXIDES
CALCIUM OXIDES
COMBUSTION
CONCENTRATION RATIO
EVAPORATION
FLUE GAS
FLY ASH
FURNACES
LEAD
LEAD SULFATES
LEAD SULFIDES
MIGRATION
PARTITION
SILICON OXIDES
SLUDGES
SODIUM SULFATES
SODIUM SULFIDES
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMICS
TITANIUM OXIDES