Suppressing Heavy Metal Leaching through Ball Milling of Fly Ash

Zhiliang Chen, Shengyong Lu, Qiongjing Mao, Alfons Buekens, Wei Chang, Xu Wang and Jianhua Yan
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Zhiliang Chen: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
Shengyong Lu: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
Qiongjing Mao: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
Alfons Buekens: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
Wei Chang: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
Xu Wang: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
Jianhua Yan: State Key Laboratory for Clean Energy Utilisation, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China

Energies, 2016, vol. 9, issue 7, 1-13

Abstract: Ball milling is investigated as a method of reducing the leaching concentration (often termed stablilization) of heavy metals in municipal solid waste incineration (MSWI) fly ash. Three heavy metals (Cu, Cr, Pb) loose much of their solubility in leachate by treating fly ash in a planetary ball mill, in which collisions between balls and fly ash drive various physical processes, as well as chemical reactions. The efficiency of stabilization is evaluated by analysing heavy metals in the leachable fraction from treated fly ash. Ball milling reduces the leaching concentration of Cu, Cr, and Pb, and water washing effectively promotes stabilization efficiency by removing soluble salts. Size distribution and morphology of particles were analysed by laser particle diameter analysis and scanning electron microscopy. X-ray diffraction analysis reveals significant reduction of the crystallinity of fly ash by milling. Fly ash particles can be activated through this ball milling, leading to a significant decrease in particle size, a rise in its BET-surface, and turning basic crystals therein into amorphous structures. The dissolution rate of acid buffering materials present in activated particles is enhanced, resulting in a rising pH value of the leachate, reducing the leaching out of some heavy metals.

Keywords: ball milling; MSWI fly ash; heavy metals; stabilization; water washing (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2016
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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