Stabilization of heavy metals in MSWI fly ash using silica fume

Journal Article · Mon Dec 15 04:00:00 EST 2014 · Waste Management

DOI:https://doi.org/10.1016/J.WASMAN.2014.08.027· OSTI ID:22443560

Li, Xinying; Chen, Quanyuan ^[1]; Zhou, Yasu ^[1]; Tyrer, Mark ^[2]; Yu, Yang ^[1]

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1. School of Environment Science and Engineering, Donghua University, Shanghai 201620 (China)
2. Mineral Industry Research Organisation, Solihull B37 7HB (United Kingdom)

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 of 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.

• OSTI ID: 22443560
• Journal Information: Waste Management, Journal Name: Waste Management Journal Issue: 12 Vol. 34; ISSN WAMAE2; ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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