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Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent
Published on: February 21, 2017
Leachability of metals from sludge-based artificial lightweight aggregate.
Fang-Chih Chang1, Shang-Lien Lo, Ming-Yu Lee
1Research Center for Environmental Pollution Prevention and Control Technology, Graduate Institute of Environmental Engineering, National Taiwan University, 71 Chou-Shan Road, Taipei 106, Taiwan, ROC.
Journal of Hazardous Materials
|January 16, 2007
Summary
Recycled metal sludge can be transformed into safe and practical lightweight aggregate (LWA) through sintering. This process immobilizes hazardous elements, preventing environmental contamination and meeting regulatory standards.
Area of Science:
- Materials Science
- Environmental Engineering
- Waste Management
Background:
- Industrial wastewater treatment generates metal sludge, a hazardous waste stream.
- Recycling metal sludge into construction materials like lightweight aggregate (LWA) offers a sustainable solution.
- Understanding the immobilization of toxic elements during LWA production is crucial for environmental safety.
Purpose of the Study:
- To investigate the feasibility of recycling metal sludge into LWA via sintering.
- To analyze the physical properties and elemental distribution in the synthesized LWA.
- To assess the environmental safety of the metal sludge-based LWA by quantifying leachable hazardous elements.
Main Methods:
- Metal sludge and mining residues were mixed and sintered at various temperatures to produce LWA.
- Scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDX) characterized LWA morphology and elemental composition.
- Sequential extraction combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) quantified hazardous element leachability.
Main Results:
- Non-sintered pellets showed high leaching concentrations of Cd, Cr, Cu, and Pb, exceeding regulatory limits.
- Sintering at 1150°C for 15 minutes significantly reduced the leachability of Cr, Cu, and Pb.
- The final LWA product exhibited concentrations of hazardous elements well within regulatory thresholds, with Cd undetected.
Conclusions:
- Sintering effectively immobilizes hazardous elements in metal sludge-based LWA, rendering them non-leachable.
- The fabricated LWA possesses favorable physical properties and poses no environmental risk.
- This study demonstrates a viable method for recycling industrial metal sludge into safe and sustainable construction materials.
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