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Updated: May 15, 2026

Two-way Valorization of Blast Furnace Slag: Synthesis of Precipitated Calcium Carbonate and Zeolitic Heavy Metal Adsorbent
Published on: February 21, 2017
Lead glass-ceramics produced from the beneficial use of waterworks sludge
Xingwen Lu1, Kaimin Shih, Hefa Cheng
1Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
Abstract:
This study quantified the effects of lead stabilization by blending lead-containing sludge into glass-ceramics through sintering with aluminum- and silica-rich precursors. Using lead oxide (PbO) to simulate lead-laden sludge under thermal conditions, the predominant PbAl(2)O(4) phase was found at temperatures of 900-1000 °C while sintering with γ-Al(2)O(3) for 3 h. To analyze the influence of silica, amorphous SiO(2) and quartz were blended with γ-Al(2)O(3) for lead stabilization. The results revealed both silica precursors could crystallochemically incorporate lead into the PbAl(2)Si(2)O(8) structure, and the weight percentage of the PbAl(2)Si(2)O(8) phase ranged from 30% to 40% in the product after 3 h of sintering at 1000 °C. Furthermore, the calcined waterworks sludge was applied as a sintering precursor and found to result in 46 wt.% of PbAl(2)Si(2)O(8) in the sintered product, suggesting an effective and feasible waste-to-resource strategy for the beneficial use of waterworks sludge. Finally, a prolonged acid leaching experiment (lasting 23 d) evaluated the stability of lead in the PbAl(2)O(4) and PbAl(2)Si(2)O(8) phases. The concentration of lead in the PbAl(2)O(4) leachate was 30-times higher than that in the PbAl(2)Si(2)O(8) leachate at the end of the experiment, suggesting a preferred lead stabilization strategy of forming the PbAl(2)Si(2)O(8) phase.
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