Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, Hong Kong SAR, China.
Water Res. 2011 Oct 15;45(16):5123-9. doi: 10.1016/j.watres.2011.07.015. Epub 2011 Jul 23.
This study investigated the mechanisms of stabilizing lead-laden sludge by blending it into the production process of aluminum-rich ceramics, and quantitatively evaluated the prolonged leachability of the product phases. Sintering experiments were performed using powder mixtures of lead oxide and γ-alumina with different Pb/Al molar ratios within the temperature range of 600-1000 °C. By mixing lead oxide with γ-alumina at a Pb/Al molar ratio of 0.5, the formation of PbAl2O4 is initiated at 700 °C, but an effective formation was observed when the temperature was above 750 °C for a 3-h sintering time. The formation and decomposition of the intermediate phase, Pb9Al8O21, was detected in this system within the temperature range of 800-900 °C. When the lead oxide and γ-alumina mixture was sintered with a Pb/Al molar ratio of 1:12, the PbAl12O19 phase was found at 950 °C and effectively formed at 1000 °C. In this system, an intermediate phase Pb3(CO3)2(OH)2 was observed at the temperature range of 700-950 °C. Over longer leaching periods, both PbAl2O4 and PbAl12O19 were superior to lead oxide in immobilizing lead. Comparing the leaching results of PbAl2O4 and PbAl12O19 demonstrated the higher intrinsic resistance of PbAl12O19 against acid attack. To reduce metal mobility, this study demonstrated a preferred mechanism of stabilizing lead in the aluminate structures by adding metal-bearing waste sludge to the ceramic processing of aluminum-rich products.
本研究通过将含铅污泥混入富铝陶瓷的生产过程中，研究了稳定含铅污泥的机制，并定量评估了产物相的浸出持久性。采用不同 Pb/Al 摩尔比的氧化铅和γ-氧化铝粉末混合物，在 600-1000°C 的温度范围内进行了烧结实验。将氧化铅与γ-氧化铝以 Pb/Al 摩尔比 0.5 混合，在 700°C 时开始形成 PbAl2O4，但当烧结时间为 3 小时且温度高于 750°C 时，可观察到有效形成。在该体系中，在 800-900°C 的温度范围内检测到中间相 Pb9Al8O21 的形成和分解。当氧化铅和γ-氧化铝混合物以 Pb/Al 摩尔比 1:12 烧结时，在 950°C 时发现 PbAl12O19 相，并在 1000°C 时有效形成。在该体系中，在 700-950°C 的温度范围内观察到中间相 Pb3(CO3)2(OH)2。在较长的浸出时间内，PbAl2O4 和 PbAl12O19 在固定铅方面均优于氧化铅。比较 PbAl2O4 和 PbAl12O19 的浸出结果表明，PbAl12O19 对酸侵蚀具有更高的内在抗性。为了降低金属迁移性，本研究通过向富铝产品的陶瓷加工中添加含金属废物污泥，证明了在铝酸盐结构中稳定铅的优选机制。
