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Title: Stabilization of heavy metals in MSWI fly ash using silica fume

Highlights: • The stabilization of heavy metals in MSWI fly ash was investigated. • The addition of silica fume effectively reduced the leaching of Pb and Cd. • The relation of solid phase transformation and leaching behavior of heavy metals was discussed. - Abstract: The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR ({sup 27}Al and {sup 29}Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals. At the addition of 20% silica fume, leaching concentrations for Cu, Pb and Zn of the hydrated paste cured for 7 days decreased from 0.32 mg/L to 0.05 mg/L, 40.99 mg/L to 4.40 mg/L, and 6.96 mg/L to 0.21 mg/L compared with the MSWI fly ash. After curing for 135 days, Cd and Pb in the leachates were not detected, while Cu and Zn concentrations decreased to 0.02 mg/L and 0.03 mg/L. The speciation of Pb and Cd by the modified version of the European Community Bureau ofmore » Reference (BCR) extractions showed that these metals converted into more stable state in hydrated pastes of MSWI fly ash in the presence of silica fume. Although exchangeable and weak-acid soluble fractions of Cu and Zn increased with hydration time, silica fume addition of 10% can satisfy the requirement of detoxification for heavy metals investigated in terms of the identification standard of hazardous waste of China.« less
Authors:
;  [1] ;  [2] ;  [1] ;  [3] ;  [1]
  1. School of Environment Science and Engineering, Donghua University, Shanghai 201620 (China)
  2. (China)
  3. Mineral Industry Research Organisation, Solihull B37 7HB (United Kingdom)
Publication Date:
OSTI Identifier:
22443560
Resource Type:
Journal Article
Resource Relation:
Journal Name: Waste Management; Journal Volume: 34; Journal Issue: 12; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ALUMINIUM 27; COMPRESSION STRENGTH; COPPER; DETOXIFICATION; DIFFERENTIAL THERMAL ANALYSIS; EXTRACTION; FLY ASH; HEAVY METALS; HYDRATION; LEACHATES; LEACHING; LEAD; NUCLEAR MAGNETIC RESONANCE; PHASE TRANSFORMATIONS; SILICA; SILICON 29; SOLID WASTES; X-RAY DIFFRACTION; ZINC